Method for producing pictorial relief structures

Abstract

The invention relates to a method for producing pictorial relief structures on a layer construction. The method comprises the provision of a layer construction having a substrate layer. After this, at least one fluid containing at least one first reactive component is applied pictorially to the substrate, wherein the pictorial application takes place in the form of a plurality of droplets with a droplet volume of less than 2 μl, and wherein the droplets are positioned pictorially. After this, there is an at least partial diffusing of the at least one first reactive component into the substrate layer for a predefined exposure time and/or an at least partial diffusing of at least one second reactive component into the pictorially positioned droplets of fluid for a predefined exposure time, wherein the substrate layer comprises the at least one second reactive component. The created relief is then fixed under the influence of heat and/or radiation via a reaction involving the first reactive component and/or the second reactive component. Further aspects of the invention relate to a pictorial relief structure produced according to the method and to the use of the pictorial relief structure as a printing form, as a microfluidic component, as a microreactor, as a phoretic cell, as a light-controlling element for color representation, as photonic crystals or as flexible parts of items of clothing.

Claims

1. A method for generatively producing pictorial relief structures on a layer construction comprising the following steps: a) providing a layer construction having a substrate layer, b) optionally, partial removing a mask layer, so that the at least one substrate layer is pictorially exposed, c) pictorial application of at least one fluid containing at least one first reactive component to the substrate layer, wherein the pictorial application takes place in the form of a plurality of droplets with a droplet volume of less than 2 μl, and wherein the droplets are positioned pictorially, d) at least partial diffusing of the at least one first reactive component into the substrate layer for a predefined exposure time and/or at least partial diffusing of at least one second reactive component into the pictorially positioned droplets of fluid for a predefined exposure time, wherein the substrate layer comprises the at least one second reactive component, wherein the predefined exposure time is at least one second and wherein the first reactive component has a molecular weight in the range of less than 1000 g/mol, wherein by means of the diffusion of the fluid or components thereof, the volume of the substrate layer in the treated area increases, giving rise to an elevated area, a relief structure, e) optionally, removing fluid remaining on the substrate layer, f) fixing of the created relief under the influence of heat and/or radiation via a reaction involving the first reactive component and/or the second reactive component, and g) optional aftertreatment of the relief.

2. The method as claimed in claim 1, wherein the at least one first reactive component and/or the second reactive component is selected from the group consisting of a polymer, an oligomer, a monomer, a low-molecular compound, a catalyst, an initiator and combinations of at least two of these components.

3. The method as claimed in claim 2, wherein the at least one first reactive component and/or the second reactive component contains at least one reactive group selected from the group consisting of a C—C double bond, C—C triple bond, acryl group, methacryl group, vinyl ether group, vinyl ester group, thiol-vinyl ester group, vinyl carbonate group, —S—H group, —N—H.sub.n(CH.sub.xR.sub.y).sub.m (where n+m=2 and m≥1 and x+y=3 and x≥1) and combinations of at least two of these reactive groups.

4. The method as claimed in claim 2, wherein the at least one catalyst or the at least one initiator is thermally and/or photochemically activatable.

5. The method as claimed in claim 1, wherein the substrate layer comprises a wax.

6. The method as claimed in claim 1, wherein the viscosity of the fluid is in the range of 0.1 to 10 mPa.Math.s based on a temperature of 20° C.

7. The method as claimed in claim 1, wherein the droplet-wise application of the fluid takes place using at least one nozzle that is movable relative to the substrate layer.

8. The method as claimed in claim 1, the contact angle of the fluid on the substrate layer is in the range of 5° to 110° .

9. The method as claimed in claim 1, wherein the removal of fluid remaining on the surface of the substrate according to step e) is carried out by a method selected from the group consisting of suctioning off, blowing off, scraping off, shaking off, washing off and combinations of at least two of these methods.

10. The method as claimed in claim 1, wherein the fixing according to step f) takes place in an inert gas atmosphere, or in that before beginning the fixing according to step f), a barrier layer is applied to the layer construction.

11. The method as claimed in claim 1, wherein the exposure time in step d) is 10 seconds to 30 minutes.

12. The method as claimed in claim 1, wherein the exposure time in step d) is 1 minute to 5 minutes.

13. The method as claimed in claim 1, wherein step b) partial removing a mask layer, so that the at least one substrate layer is pictorially exposed, is required.

14. The method as claimed in claim 1, wherein the relief structure has a height after a single application of a fluid is in the range of 0.01 μm to 50 μm and/or wherein after multiple applications of fluid, the relief height is in the range of 0.05 μm to 1000 μm.

15. The method as claimed in claim 1, wherein the relief structure has a height after a single application of a fluid is in the range of 1 μm to 10 μm and/or wherein after multiple applications of fluid, the relief height is in the range of 1 μm to 10 μm.

16. The method as claimed in claim 1, wherein the substrate layer comprises surfactant substances selected from: surfactants, amphiphilic molecules with hydrophobic and hydrophilic areas, and block copolymers and oligomers containing blocks having a lower surface energy in order to exert an action as a mobile blocking layer for oxygen and/or prevent excessive spreading of the applied fluid droplets.

17. The method as claimed in claim 1, wherein the substrate layer comprises at least one elastomeric binder which is a hydrophobic binder which is not or at least not substantially swellable in water.

18. The method as claimed in claim 17, wherein the elastomeric binder is an elastomeric block copolymer of alkenyl aromatics and 1,3-dienes having at least one styrene-isoprene block copolymer or styrene-butadiene block copolymer.

19. A method for producing pictorial relief structures on a layer construction comprising the following steps: a) providing a layer construction having a substrate layer, b) optionally, partial removing a mask layer, so that the at least one substrate layer is pictorially exposed, c) pictorial application of at least one fluid containing at least one first reactive component to the substrate layer, wherein the pictorial application takes place in the form of a plurality of droplets with a droplet volume of less than 2 μl, and wherein the droplets are positioned pictorially, d) at least partial diffusing of the at least one first reactive component into the substrate layer for a predefined exposure time and/or at least partial diffusing of at least one second reactive component into the pictorially positioned droplets of fluid for a predefined exposure time, wherein the substrate layer comprises the at least one second reactive component, wherein the predefined exposure time is at least one second, e) optionally, removing fluid remaining on the substrate layer, f) fixing of the created relief under the influence of heat and/or radiation via a reaction involving the first reactive component and/or the second reactive component, and g) aftertreatment of the relief, wherein the aftertreatment comprises application of a further layer to the produced relief structures, wherein the further layer is configured such that it does not follow the shape of the relief, so that cavities and/or channels are produced between the substrate layer and the further layer.

20. A method for generatively producing pictorial relief structures on a layer construction comprising the following steps: a) providing a layer construction having a substrate layer, b) optionally, partial removing a mask layer, so that the at least one substrate layer is pictorially exposed, c) pictorial application of at least one fluid containing at least one first reactive component to the substrate layer, wherein the pictorial application takes place in the form of a plurality of droplets with a droplet volume of less than 2 μl, and wherein the droplets are positioned pictorially, d) at least partial diffusing of the at least one first reactive component into the substrate layer for a predefined exposure time and/or at least partial diffusing of at least one second reactive component into the pictorially positioned droplets of fluid for a predefined exposure time, wherein the substrate layer comprises the at least one second reactive component, wherein the predefined exposure time is at least one second, wherein by means of the diffusion of the fluid or components thereof, the volume of the substrate layer in the treated area increases, giving rise to an elevated area, a relief structure; e) optionally, removing fluid remaining on the substrate layer, f) fixing of the created relief under the influence of heat and/or radiation via a reaction involving the first reactive component and/or the second reactive component.

Description

EXAMPLES

Example 1

(1) For contact angle measurement, plates comprising a polymeric binder, a plasticizer, and a photoinitiator were extruded, and 1 μl droplets of fluids (acrylic compounds) were deposited thereon using a pipette. In each case, the contact angle was determined immediately after deposition of the droplets.

(2) The plate-shaped materials were produced as follows: a mixture (see Table 1a for the composition of the individual plates and Table 1b for the chemical properties of the components) containing a polymeric binder, a plasticizer oil and 5 parts of benzyl dimethyl ketal as a photoinitiator was melted in an extruder at elevated temperatures (120° C. to 180° C.) and calendered via a wide slit nozzle between two PET films with a thickness of 125 μm so that the substrate layer (photopolymer+carrier film) had a thickness of 1450 μm. The lower PET film is used as a carrier film and the upper PET film as a protective layer.

(3) After removal of the upper PET film, using a pipette (“Dispenser” from VWR with pipette tips of corresponding volume), droplets of a fluid were deposited with a volume of 1 μl on the surfaces of plates 1 and 5. Using a microscope (Digital Microscope VHX-500F from Keyence), the contact angle was measured immediately after application. Moreover, the viscosity of the different monomers was also measured (see Tab. 1c).

(4) Viscosity was measured using an MC 120 rotational rheometer (from Physica) with a cone and plate geometry at 20° C., wherein the cone had a diameter of 50 mm and an angle of 1°. Measurement was effected at a rotation speed of 120 rpm for a period of 2 minutes at a shear rate of 720 s.sup.−1 and the software UC 200/32 (V 2.50) was used.

(5) For contact angle measurement, a microscope (Digital Microscope VHX 500F with objective VH-Z250R from Keyence) was tilted by 90° so that the droplets could be examined and measured from the side. The contact angle is the angle between the substrate surface and the tangents on the droplet surface at the point of contact. As fluids, ethylhexyl acrylate (EHA), hexanediol diacrylate (HDDA), hexanediol dimethacrylate (HDMA), pentaerythritol triacrylate (PETA), and 2-hydroxyethyl acrylate (HEA) were tested. In addition, a mixture of HDDA and HDMA with a mixing ratio of 1:1 was tested.

(6) TABLE-US-00001 TABLE 1a Compositions Benzyl White Polybutadiene Hexamoll dimethyl Binder oil oil DINCH ketal Plate 1 Binder 1 10% 5% Plate 2 Binder 2 20% 5% Plate 2 Binder 3 20% 5% Plate 4 Binder 4 20% 5% Plate 5 Binder 5 10% 5% Plate 6 Binder 4 20% 10% 

(7) TABLE-US-00002 TABLE 1b Chemical properties of the binders and plasticizers Kinematic Styrene/ethylene/ viscosity Binders/oils Chemical nature vinyl content/M.sub.n Hardness (DIN 51562) Binder 1 SIS rubber 14% styrene 42° Shore A Binder 2 SBS rubber 25% styrene 61° Shore A Binder 3 EPDM rubber 70% ethylene no data Binder 4 SBS rubber 60% styrene 84° Shore A Binder 5 SIS rubber 15% styrene 32° Shore A Polybutadiene High-vinyl >85% vinyl oil polybutadiene oil M.sub.n = 1100 g/mol White oil Highly refined M.sub.n = 300 g/mol 70 mm.sup.2/s mineral oil (40° C.)

(8) TABLE-US-00003 TABLE 1c Variation in droplet surface tension Fluid HDDA/ HDMA EHA HDDA HDMA PETA HEA 1/1 Contact angle 26.1° 16.5° 27.4° 48.1 on plate 1 Contact angle 12.6° 25.0° 25.5° 40.0° 39.46° 22.41 on plate 5 Viscosity 0.4 5.3 4.2 1127 (mPa .Math. s)

(9) TABLE-US-00004 TABLE 1d Variation in substrate layer surface tension Substrate Plate 1 Plate 2 Plate 3 Plate 4 Plate 5 Contact angle 16.5 20.8 22.1 38.5 25.0° with HDDA

(10) Tables 1c and 1d show that by selecting the fluid and/or the substrate layer, the contact angle can be varied over a wide range. It is also clear that fluids with sharply differing viscosity can be used.

Example 2

(11) Production of plate-shaped materials: For example 2a, a mixture containing 65 parts of an SBS (styrene-butadiene-styrene) copolymer (SBS triblock, with a styrene content of 24% and a molecular weight Mw of 130,000 g/mol) as a binder, 10 parts of hexanediol diacrylate (HDDA), 20 parts of a 1:1 mixture of a low-vinyl polybutadiene oil (vinyl <2%, Mn=5000 g/mol) and a high-vinyl polybutadiene oil (vinyl >85%, Mn=1100 g/mol), 2 parts of benzyl dimethyl ketal as a photoinitiator, and as further components, 2 parts of 3,5-di-tert-butyl-4-hydroxytoluene and 1 part dye (Orasol Blue), was melted in an extruder at elevated temperatures (120° C. to 180° C.) and calendered via a wide slit nozzle between two PET films with a thickness of 125 μm, so that the substrate layer (photopolymer+carrier film) had a thickness of 1450 μm. In example 2b, 2 wt. % of a paraffin wax (setting point 58° C. to 60° C., density 0.91 g/cm.sup.2) was additionally used.

(12) After removal of the upper PET film, using a pipette (“Dispenser” from VWR with pipette tips of corresponding volume), droplets of the fluid F1, composed of hexane diol diacrylate (Laromer HDDA BASF), were deposited with a volume of 1 μl on the plate surfaces. Using a microscope (Digital Microscope VHX-500F from Keyence), the droplet diameter (Ø.sub.0) was measured immediately after application. After 20 minutes, during which the HDDA had time to diffuse in, the diameter (Ø.sub.20) was again measured. After this, the supernatant fluid was removed by rinsing with a mixture of 1-propanol/water (4:1), and the surface was exposed for 10 min to UVA (Flint Group, Fill exposure unit main exposure) and then for 5 min to UVC (Flint Group, Fill light finishing drawer). The resulting reliefs were measured with a Perthometer, and the height of the elevation H and the diameter at half height (ØR) were determined. The tests were carried out 5 times each, and the measured values given represent the arithmetic mean.

(13) The Perthometer measurements were carried out with a MarSurf M 300 mobile roughness meter from Mahr using the software “MarWin XR20” (V 4.26). A scanning rate of 0.5 mm/s and a measurement force of 0.00075 N were used.

(14) TABLE-US-00005 TABLE 2 Values standardized to example 2a Wax (%) Contact angle Ø.sub.0 Ø.sub.20 Ø.sub.R H Example 2a 0 1 1 1 1 1 Example 2b 2 1.3 0.89 0.89 0.89 1

(15) Table 2 shows that relief structures can be obtained in this manner and that because wax is used, a higher contact angle is produced, the fluid droplets spread out less, and structures can be produced with more precise detail. Moreover, it was found that with use of wax, the relief structures were stable after shorter exposure times.

Example 3

(16) Production of plate-shaped materials: For example 3a, a mixture containing 85 parts of an SIS (styrene-isoprene-styrene) copolymer (Mw=240,000 g/mol, styrene content 14.3%, 25% diblock), 10 parts of a medicinal white oil (Mn=300 g/mol), and 5 parts of benzyl dimethyl ketal was melted in an extruder at elevated temperatures (120° C. to 180° C.) and calendered via a wide slit nozzle between two PET films with a thickness of 125 μm, so that the layer construction had a thickness of 1450 μm. In examples 3b and 3c, 2 or 4 wt. % of a paraffin wax (setting point 58° C. to 60° C., density 0.91 g/cm.sup.2) was additionally used.

(17) After carrying out the same method as in example 2, the surfaces were provided with fluid F1. After diffusion, the surfaces were exposed for a duration of 20 minutes. The results are shown in Table 3.

(18) TABLE-US-00006 TABLE 3 Values standardized to example 3a Wax (%) Contact angle Ø.sub.0 Ø.sub.20 Ø.sub.R H Example 3a 0 1 1 1 1 1 Example 3b 2 1.61 0.85 0.83 0.8 1.125 Example 3c 4 1.64 0.92 0.88 0.8 1.04

(19) Table 3 shows that relief structures can be obtained in this manner and that because wax is used, a higher contact angle is produced, the fluid droplets spread out less, and structures can therefore be produced with greater height and more precise detail.

Example 4

(20) In example 4, the plate-shaped materials of examples 2a and 3a to 3c were used and treated as follows.

(21) Using the pipette, droplets of fluid F1 were placed on the substrate layer with a volume of 1 μl. After a waiting period of 20 minutes, the portion of the fluid F1 that had not diffused in was removed with a solvent mixture of 1-propanol/water (4:1) from the surface and a second droplet of the fluid F1 was applied with a volume of 0.5 μl to the already formed relief structure at the location of the first droplet. Using the microscope, the droplet diameter (Ø.sub.0) was measured immediately after application of the second droplet. After 20 minutes, during which the monomer had time to diffuse in, the diameter (Ø.sub.20) was again measured. After this, supernatant fluid was removed by rinsing with a mixture of 1-propanol/water (4:1), and the surface was exposed under the same conditions as in example 1. The resulting reliefs were measured with the Perthometer, and the height of the elevation H and the diameter at half height (ØR) were determined. The tests were carried out 5 times each, and the measured values given represent the arithmetic mean.

(22) TABLE-US-00007 TABLE 4 Values standardized to example 2a Wax (%) Ø.sub.0 Ø.sub.20 Ø.sub.R H Example 2a 0 1 1 1 1 Example 3a 0 1.28 1.27 0.96 1.29 Example 3b 2 0.93 0.9 0.85 1.88 Example 3c 4 0.96 0.95 0.83 2.29

(23) Table 4 shows that the height of the relief structures can be increased by application of further droplets and that because wax is used, the fluid droplets do not spread, allowing structures to be produced that have more precise detail and are higher.

Example 5

(24) Example 2 was repeated, but using the fluid F2, composed of 98 wt. % hexanediol diacrylate and 2 wt. % benzyl dimethyl ketal. It was found that the similarly dimensioned reliefs were already stable after significantly shorter exposure times (reduced by at least half).

Example 6

(25) Example 2 was repeated, but using the fluid F3, composed of 95 wt. % hexanediol diacrylate and 2 wt. % triethanolamine. It was found that the similarly dimensioned reliefs were already stable after approximately 20% shorter exposure times.

Example 7

(26) Example 2 was repeated, but using the fluid F4, composed of 99.5 wt. % hexanediol diacrylate and 0.5 wt. % butylhydroxytoluene. It was found that the formulation F4 was significantly more stable and the pipette tips became blocked to a lesser extent and approximately 5 to 10 times more slowly.

Example 8

(27) Example 1 was repeated, but using the fluid F5, composed of 95 wt. % hexanediol diacrylate and 5 wt. % azoisobutyronitrile. In this case, before fixing according to step f), a 0.5 μm thick PET film was laminated onto the surface as a barrier layer. After this, the sample was treated for 1 h at 150° C. in an oven (FDL 115 from Binder GmbH). Relief structures were obtained the heights of which could be increased by wiping off with a cloth saturated in a mixture of 33 wt. % cyclohexanol, 47 wt. % of a hydrocarbon mixture (CAS: 64742-47-8 and 64742-48-9) with a low aromatic content and 20 wt. % diisopropylbenzene. Both with and without this wiping off, the stability of the relief structures could be sharply increased by subsequent exposure (10 min to UVA (Flint Group, Fill exposure unit main exposure) and then 5 min to UVC (Flint Group, Fill light finishing drawer).

Example 9

(28) Example 1 was repeated, but a PET film was laminated onto the surface prior to exposure. It was found that the similarly dimensioned reliefs were already stable after significantly shorter exposure times.

Example 10

(29) Production of plate-shaped materials: A mixture containing 85 parts of an SIS copolymer (Mw=240,000 g/mol, styrene content 14.3%, 25% diblock), 10 parts of a medicinal white oil (Mn=300 g/mol), and 5 parts of benzyl dimethyl ketal was melted at elevated temperatures (120-180° C.) in an extruder and calendered via a wide slit nozzle between two PET films with a thickness of 125 μm, so that the layer construction had a thickness of 1450 μm.

(30) After removal of the upper PET film, using a pipette (“Dispenser” from VWR with pipette tips of corresponding volume), droplets of the fluid F1, composed of hexanediol diacrylate (Laromer HDDA BASF), were deposited with a volume of 1 μl on the plate surfaces.

(31) After this, the supernatant fluid was removed by rinsing with a mixture of 1-propanol/water (4:1), and the surface was exposed for 10 min to UVA (Flint Group, Fill exposure unit main exposure) and then for 5 min to UVC (Flint Group, Fill light finishing drawer). After this, the surfaces were heated by means of an IR emitter so that the non-swollen and crosslinked areas became viscous. The heated surface was brought into contact one or several times with a polyester web, and softened areas were removed when the web was peeled off. After cooling, the relief heights were found by measurement to be elevated by up to 100%.

Example 11

(32) Example 2a was repeated, but after peeling off the upper PET film, an imageable mask layer was applied. For this purpose, a coating solution of 70 wt. % polyvinyl alcohol (degree of saponification of approx. 72 mol %, viscosity of a 4 wt. % solution in water approx. 6 mPa.Math.s), 29.8% Levanyl Black A-SF, and 0.02% Zonyl FSN in a solvent mixture (water/n-propanol 3:1) with a solid content of 5% was produced. The coating solution was blade-coated onto a 100 μm thick Mylar film and dried. The produced mask layer had a dry layer thickness of 3 μm. The Mylar film coated with the laser-ablatable mask layer was laminated onto the substrate layer at a laminating temperature of 120° C. After cooling of the composite, the Mylar film was peeled off, with the laser-ablatable mask layer remaining on the substrate layer.

(33) The layer construction of carrier film, substrate layer and laser-ablatable mask layer was fixed onto the drum of an IR laser (Thermoflex 20, Xeikon) and imaged with a power of 30 W at a resolution of 5080 dpi. Dots with a diameter of 20 μm, 40 μm, 60 μm, and 80 μm were written in as pictorial information. Individual droplets of the fluid F2 were applied to the openings, after a waiting period of 10 minutes, rinsing was carried out with a water/n-propanol 3:1 solution until the mask layer was completely washed off, and the surface was exposed for 10 min to UVA (Flint Group, Fill exposure unit main exposure) and then for 5 min to UVC (Flint Group, Fill light finishing drawer). Relief structures were obtained having a relief height slightly lower than when no mask layer was applied. In further tests, the openings of the mask layer were provided with fluid F2, with the same layer construction and the same exposure conditions, but they were first exposed, after which the mask layer was removed by rinsing with the water/isopropanol mixture. After this, drying was carried out for 20 minutes at 50° C. Relief structures were obtained with a relief height of up to 50% greater than without the mask layer.

Example 12

(34) Using a plate produced according to example 1 and a reference plate without a photoinitiator, after removal of the upper PET film, droplets were deposited in each case with a pipette in a volume of 10 μl pentaerythritol tetraacrylate (PETA Sigma-Aldrich) on the plate surfaces and left there for 1 h. After this, exposure was carried out for 15 minutes (Flint Group, Fill exposure unit main exposure). Non-polymerized PETA was removed with a cloth, and the height of the resulting relief was measured at 650 μm. For the reference plate without the photoinitiator, all of the PETA was removed, and no swelling of the plate was observed. This means that diffusion of a reactive component (the photoinitiator) from the substrate layer into the PETA droplets had occurred, and this component had been at least partially fixed by the subsequent exposure.

Example 13

(35) Production of plate-shaped materials: A mixture containing 65 parts of an SBS copolymer (SBS triblock, with a styrene content of 24% and a molecular weight Mw of 130,000 g/mol) as a binder, 10 parts of hexanediol diacrylate, 20 parts of a 1:1 mixture of a low-vinyl polybutadiene oil (vinyl >2%, Mn=5000 g/mol) and a high-vinyl polybutadiene oil (vinyl >85%, Mn=1100 g/mol), 2 parts of benzyl dimethyl ketal as a photoinitiator, and as further components, 2 parts of 3,5-di-tert-butyl-4-hydroxytoluene and 1 part dye (Orasol Blue), was melted in an extruder at elevated temperatures (120° C. to 180° C.) and calendered via a wide slit nozzle between two PET films with a thickness of 125 μm, so that the substrate layer (photopolymer+carrier film) had a thickness of 1450 μm. As in example 2b, 2 wt. % of a paraffin wax was additionally used (setting point 58-60° C., density 0.91 g/cm).

(36) Using an Omni Jet 100 (Unijet), droplets of hexanediol diacrylate were applied with a volume of 6-7 μl per droplet to these plates. Four rows of 10 fields each consisting of 25×25 individual droplets were applied. Printing of one row took one minute, and the first row was fixed by exposure after an exposure time of 1 minute, the second row after 4 minutes, the third row after 7 minutes, and the fourth row after 10 minutes. Exposure was carried out using a Rapid 3000 Lamp (Welisch Elektronik GmbH) with a power of 3 mW/cm.sup.2 at a distance of 75 mm for 12 minutes. As a result, 40 relief structures were obtained with an areal extent of approx. 1 mm×1 mm whose height varied depending on the exposure time. For illustrative purposes, the heights of the first fields of a row are indicated as measured using a Perthometer.

(37) It can be seen from FIG. 1 that with increasing exposure time t, the height h of the relief structure produced increases approximately linearly.

Example 14

(38) As was described with respect to example 13, droplets were applied to a plate, but a row of 30 fields of 50×50 droplets was first printed on, and after a waiting period of 730 seconds, a second layer of fields composed of 25×25 droplets was applied to the center of the fields produced. This structure was then exposed as in example 13 for 3 minutes.

(39) After fixing, the first layer had an edge length of approx. 1 mm and a height of 20 μm to 24 μm. The second layer had an edge length of approx. 800 μm and a height of 3 μm to 7 μm.

Example 15

(40) The tests of example 14 were repeated, but exposure was carried out for 3 minutes after application of the first layer with an exposure time of 3 minutes (same conditions as in example 13). After this, the second layer of 25×25 droplets was applied to the existing fields and again exposed for 3 minutes after a further exposure time of 3 minutes.

(41) After the wide area fixation, the first layer had an edge length of approx. 1 mm and a height of 18 μm to 25 μm. The second layer had an edge length of approx. 800 μm and a height of 2 μm to 8 μm.