PHOTOPOLYMERIZABLE RELIEF PRECURSOR HAVING ADJUSTABLE SURFACE PROPERTIES

Abstract

A photopolymerisable relief precursor includes a dimensionally stable carrier, and a photopolymerisable relief-forming layer at least containing a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a migration-capable, surface-active additive, a photoinitiator activatable with UVA light and a photoinitiator activatable with UVC light. A method for producing a relief structure.

Claims

1. A photopolymerisable relief precursor comprising: (A) a dimensionally stable carrier, and (B) a photopolymerisable relief-forming layer at least containing a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a migration-capable, surface-active additive, a photoinitiator activatable with UVA light and a photoinitiator activatable with UVC light.

2. The photopolymerisable relief precursor according to claim 1, wherein the migration-capable, surface-active additive is selected from the group consisting of ionic or non-ionic surfactants, long-chain hydrocarbons, waxes, paraffin waxes, organosilicon compounds, silicon oils, silanes and siloxanes, or mixtures thereof.

3. The photopolymerisable relief precursor according to claim 1, wherein the migration-capable, surface-active additive is a paraffin wax.

4. The photopolymerisable relief precursor according to claim 1, wherein the migration-capable, surface-active additive is a polysiloxane polyester acrylate.

5. The photopolymerisable relief precursor according to claim 1, wherein the photoinitiator activatable with UVA light is selected from the group consisting of benzil ketals, acylphosphine oxides, bisacylphosphine oxides, aminophenyl ketones, phenyloxime esters and mixtures thereof.

6. The photopolymerisable relief precursor according to claim 1, wherein the photoinitiator activatable with UVC light is selected from the group consisting of hydroxyphenyl ketones, benzoyl formates, benzophenones, arylalkyl ketones, arylbenzyl ketones and mixtures thereof.

7. The photopolymerisable relief precursor according to claim 5, wherein the photoinitiator activatable with UVA light is selected from the group consisting of diphenyl (2,4,6-trimethyl benzoyl)phosphine oxide, benzil dimethyl ketal and benzil diethyl ketal and the photoinitiator activatable with UVC light is selected from the group consisting of oxyphenyl acetic acid 2-[2-oxo-2-phenylacetoxy-ethoxy]ethylester, oxyphenyl acetic acid 2-[2-hydroxyethoxy]ethylester, methylbenzoyl formate, p-tolyl undecyl ketone, 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenyl propane-1-on and mixtures thereof.

8. The photopolymerisable relief precursor according to claim 1, wherein the photopolymerisable relief-forming layer contains the migration-capable, surface-active additive in an amount of 0.1 to 10% by weight based on the weight of the photopolymerisable relief-forming layer.

9. The photopolymerisable relief precursor according to claim 1, wherein the photopolymerisable relief-forming layer contains the photoinitiator activatable with UVA light in an amount of 0.5 to 20% by weight based on the overall weight of the photopolymerisable relief-forming layer.

10. The photopolymerisable relief precursor according to claim 1, wherein the photopolymerisable relief-forming layer contains the photoinitiator activatable with UVC light in a concentration of 0.1 to 20% by weight based on the overall weight of the photopolymerisable relief-forming layer.

11. The photopolymerisable relief precursor according to claim 1, wherein the mass ratio of photoinitiator activatable with UVA light to photoinitiator activatable with UVC light is 0.1 to 50.

12. A method for the production of a relief structure, comprising the following steps: (i) provision of a photopolymerisable relief precursor containing at least one migration-capable, surface-active additive, (ii) application of a mask or generation of a structured mask layer above the photopolymerisable relief-forming layer, (iii) optionally exposure of the back side to electromagnetic radiation through the carrier layer, (iv-a) exposure of the photopolymerisable relief-forming layer to electromagnetic radiation through the mask or mask layer, (v) removal of the mask or mask layer, any further layers that may be present and the non-photopolymerised regions of the relief-forming layer not exposed in step (iv), thereby generating a relief, (vi) optional drying of the relief, (vii) re-exposure of the relief from the side facing away from the carrier layer to UVA light in the wavelength range from 315 to 380 nm and/or to UVC light in the wavelength range from 200 to 280 nm, whereby the relief is re-crosslinked and its permeability for the migration-capable surface-active additive is adjusted, for adjustment of the surface properties of the relief, and (viii) optionally further processing steps.

13. A method for the production of a relief structure, comprising the following steps: (i) provision of a photopolymerisable relief precursor containing at least one migration-capable, surface-active additive, (iii) optionally exposure of the back side to electromagnetic radiation through the carrier layer, (iv-b) imaging exposure of the photopolymerisable relief-forming layer to electromagnetic radiation, (v) removal of any further layers that may be present and the non-photopolymerised areas of the relief-forming layer not exposed in step (iv), thus generating a relief, (vi) optional drying of the relief, (vii) re-exposure of the relief from the side facing away from the carrier layer to UVA light in the wavelength range from 315 to 380 nm and/or to UVC light in the wavelength range from 200 to 280 nm, whereby the relief is re-crosslinked and its permeability for the migration-capable surface-active additive is adjusted, for adjustment of the surface properties of the relief, and (viii) optionally further processing steps.

14. The method according to claim 12, wherein in step (vii) the re-exposure is to UVA light and UVC light, whereby the re-exposure to UVA light and UVC light takes place simultaneously, consecutively or alternately.

15. The method according to claim 12, wherein the re-exposure conditions are adjusted as a function of the type of printing ink, for adjustment of the surface properties of the relief for the printing ink.

16. The method according to claim 15, wherein through the choice of re-exposure conditions the surface properties can be adjusted in such a way that the printing plate is suitable for printing with solvent-based inks, aqueous inks or UV-curing inks.

17. The method according to claim 12 for the production of an optimised relief structure, wherein the method is performed multiple times with the steps (i) to (viii), whereby in step (vii) the re-exposure to UVA light and/or UVC light is varied in respect of the dose and/or of the chronological sequence of the UVA and UVC re-exposure steps in order to optimise the surface properties of the relief.

18. The method according to claim 12, wherein the migration of the at least one migration-capable, surface-active additive is controlled by selection of the exposure parameters of the re-exposure step.

19. The method according to claim 12, wherein there is re-exposure to UVA light with a dose from 100 to 30,000 mJ/cm2, preferably 100 to 20,000 mJ/cm2, more preferably 100 to 7,000 mJ/cm2 and very preferably 500 to 7,000 mJ/cm2 UVA light.

20. The method according to claim 12, wherein there is re-exposure to UVC light with a dose from 100 to 20,000 mJ/cm2 UVC light.

21. The method according to claim 12, wherein the ratio of doses of UVA to UVC light (DUVA/DUVC) is greater than 0.2.

22. The method according to claim 12, wherein the exposure to UVC light seals the surface of the layer due to the lower depth of penetration and the exposure to UVA light ensures stronger crosslinking throughout the layer.

23. The relief structure obtainable using the method according to claim 12.

24. Use of the relief structure according to claim 23 as a pad printing plate, flexographic plate, letterpress plate, gravure plate, microfluidic component, microreactor, phoretic cell, photonic crystal or optical component.

25. The relief structure obtainable using the method according to claim 13.

Description

EXAMPLES

Methods:

Evaluation of the Inflow

[0078] To evaluate the inflow, the plates were assessed after about 1,000 linear metres of printing by assessing the tonal value fields from 10% to 50%. A significant inflow (a lot of ink in the interstitial spaces) was given the classification “—”, moderate inflow the classification “0” and little to no inflow (no ink in the interstitial spaces) the classification “+”.

Method for Gloss Measurement

[0079] Gloss measurements were carried out to provide evidence for a migration-capable, surface-active additive (MSA) on the surface of the plate. The gloss was measured with the aid of a micro-TRI-gloss μ gloss meter (BYK—Gardner GmbH) at a glancing angle of 60°. The gloss meter was calibrated prior to the measurements with the aid of the integrated calibration standard. The result is the mean of three measurements at each of different points on the surface of the plate. Removal of the MSA by cleaning the surface with solvent leads to an increase in the gloss to 40-50 GU

[0080] FIGS. 1 to 3 show the development of the gloss in gloss units (GU) as a function of the time in days for different re-exposure times.

Method for IR Measurement

[0081] FT-IR measurements were carried out to provide evidence of the MSA on the surface of the plate. A tensor 27 FT-IR (Bruker) equipped with a PIKE MIRacle Diamant/ZnSe ATR-IR unit (PIKE Technologies) was used for the FT-IR measurements on the surface of the plate. The data were captured and analysed with the aid of the Opus software, version 7.5 (Bruker). Background correction of the spectra was performed automatically. The integrals of the IR bands at 719 and 729 cm.sup.−1 were used as the measure for the presence of the MSA. To that end they were standardised to the integral of the IR-band at 1730 cm.sup.−1 and the zero value (result without MSA) was then subtracted. The signals attributable to the MSA were determined by IR spectroscopy of the pure substance. Following removal of the MSA by cleaning the surface with solvent, the signals attributable to the MSA in the IR spectrum are no longer visible.

[0082] FIGS. 4 to 6 show the integrals of the IR bands at 719 and 729 cm.sup.−1 after 7 days for the given re-exposure times.

Method for Contact Angle Measurement

[0083] The effect of the MSA on the wetting of the surface with water was investigated by means of contact angle measurements. To that end a drop of 10 μL of demineralised water was dropped onto the surface of a printing plate. The profile of the water droplet was captured by means of the Keyence VHX-500F light microscope using the VH-Z20R lens and the VH-S30 tripod. The radius r and the height h of the droplet were measured from these captures by means of the associated software. The contact angle θ was calculated using trigonometry (equation 1).

[00001]$\begin{array}{cc}\theta =\mathrm{arc}\cos \left(1-\frac{h}{r}\right)& \left(1\right)\end{array}$

Example 1

[0084] An SBS-based relief precursor (overall thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C20) having a melting point of 50-57° C. as MSA and 2% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). The relief precursor was exposed from the back for 25 seconds with an intensity of 16 mW/cm.sup.2 in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently exposed through the mask layer for 15 minutes with an intensity of 16 mW/cm.sup.2 at 40° C. in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). The exposed precursor was washed out in a Nyloflex® Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 220 mm/min. Drying took place at 60° C. over 120 minutes. Different re-exposures were then carried out in a Nyloflex® Combi FIII exposure unit, whereby no, only UVA (Philips TL 60W/10-R, intensity 11 mW/cm.sup.2), only UVC (Philips TUV 75W HO G75 T8, intensity 13 mW/cm.sup.2), sequential and simultaneous UVA and UVC exposures were used, in each case at 40° C. In this context simultaneous means that both exposures (with UVA and UVC) were started at the same time. IR and gloss measurements on the printing surfaces thus formed were then carried out at intervals of time. The reference did not contain any MSA. 1A means 1 min of re-exposure to UVA light, 1C means 1 min of re-exposure to UVC light.

[0085] FIGS. 1, 2 and 3 show the progression of the gloss on the surfaces of the printing plates over time under various re-exposure conditions. As the MSA diffuses onto the surface, the gloss value falls. When compared with FIGS. 4, 5 and 6, it can be seen that a decline in the gloss value is associated with an increase in the IR signal. With 3 min of re-exposure to UVC (FIG. 1), no clear influence of the UVA re-exposure time on the MSA migration is yet discernible. With 10 min of re-exposure to UVC (FIG. 2), the amount of MSA reduces sharply as the re-exposure time rises. The influence of the re-exposure to UVC on the migration of the MSA is felt at its strongest when combined with 10 min of re-exposure to UVA. In the case of 10 min of exposure to UVA and 10 min of re-exposure to UVC, much less MSA reaches the printing surface than is the case for 10 min of re-exposure to UVA without exposure to UVC (FIG. 3). The properties of the printing surface can thus be controlled.

TABLE-US-00001 TABLE 1 IR integrals and gloss on the printing surface after 2 days UVA UVC UVC 1/ UVA dose time dose UVA/ IR Gloss gloss Example Designation time (min) (mJ/cm.sup.2) (min) (mJ/cm.sup.2) UVC (a.u.) (GU) (1/GU) Reference 1 No MSA 10 6600 0 0 >100 0.00 41 0.025 Example 1a No re- 0 0 0 0 >100 0.71 16 0.062 exposure Example 1b 10A 10 6600 0 0 >100 0.32 12 0.086 Example 1c 5C 0 0 5 3900 0.0 0.05 32 0.031 Example 1d 10A5C 10 6600 5 3900 1.7 0.08 32 0.031 simultaneous Example 1e 10A10C 10 6600 10 7800 0.8 0.02 35 0.028 simultaneous

[0086] Table 1 shows the IR integrals and gloss on the printing surface after 2 days as a function of the re-exposure conditions. The greater the value of the IR integral, the more MSA there is on the surface of the plate. The IR integral correlates with the reciprocal of the gloss. A low gloss is evidence of the presence of MSA on the surface. In the absence of MSA, no MSA can be found by means of IR spectroscopy. In the case of 10 min of exposure to UVA and 10 min of re-exposure to UVC, much less MSA reaches the printing surface than is the case without re-exposure or for 10 min of re-exposure to UVA without exposure to UVC. The properties of the printing surface can thus be controlled.

TABLE-US-00002 TABLE 2 IR integrals and gloss on the printing surface after 7 days UVA UVC UVC 1/ UVA dose time dose UVA/ IR Gloss gloss Example Designation time (min) (mJ/cm.sup.2) (min) (mJ/cm.sup.2) UVC (a.u.) (GU) (1/GU) Reference 1 No MSA, 10 6600 0 0 >100 0 40 0.025 10A Example 1a Nore- 0 0 0 0 >100 0.79 9 0.107 exposure Example 1b 10A 10 6600 0 0 >100 0.54 7 0.147 Example 1f 2A3C 2 1320 3 2340 0.6 0.34 14 0.070 simultaneous Example 1g 5A3C 5 1500 3 2340 1.4 0.16 16 0.063 simultaneous Example 1h 10A3C 10 3000 3 2340 2.8 0.35 17 0.057 simultaneous Example 1i 10C 0 0 10 7800 0.0 0.21 20 0.050 Example 1j 2A10C 2 1320 10 7800 0.2 0.10 34 0.030 simultaneous Example 1k 5A10C 5 3300 10 7800 0.4 0.04 37 0.027 simultaneous Example 1l 10A10C 10 6600 10 7800 0.8 0.06 37 0.027 simultaneous

[0087] Table 2 shows the influence of the UVA and UVC exposure on the presence of the MSA on the surface of the plate. The duration of 7 days was chosen in order to verify that the MSA does not actually reach the surface. Reference 1 shows the values arising without MSA. The less UVA and UVC light was applied to printing plates with MSA, the more MSA is present on the surface after 7 days. The influence of UVC light here is greater than that of UVA light. The values that were obtained for the combination of UVA and UVC re-exposure correspond to the values of a printing plate without MSA.

Example 2

[0088] a) An SIS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.) and 0.5% by weight of 1-hydroxycyclohexylphenyl ketone (IGM Resins B.V.).

[0089] b) A second relief precursor, but without 1-hydroxycyclohexylphenyl ketone, was likewise produced as under a).

[0090] Both plate types were exposed from the back for 15 seconds (a) and 10 seconds (b) with an intensity of 16 mW/cm.sup.2 in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). After the protective film was peeled off, the precursors were imaged in a ThermoFlexX 20 (Xeikon) and subsequently exposed through the mask layer for 15 minutes with an intensity of 16 mW/cm.sup.2 at 40° C. in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). The precursors were washed out in a Nyloflex® Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 200 mm/min. Drying took place at 60° C. over 120 minutes. Different re-exposures were then carried out at 40° C. in a Nyloflex® Combi FIII exposure unit, whereby UVA and UVC exposures were used in parallel and started simultaneously. In the former case, there was 10 minutes of UVA exposure (Philips TL 60W/10-R) with an intensity of 11 mW/cm.sup.2 and 3 minutes of UVC exposure (Philips TUV 75W HO G75 T8) with an intensity of 13 mW/cm.sup.2. In the latter case, there was 10 minutes of UVA exposure and 10 minutes of UVC exposure. Gloss measurements on the non-printed areas thus formed (floor) were then carried out at intervals of time.

TABLE-US-00003 TABLE 3 Gloss after 3 days and inflow of the printing plates with solvent-based ink (LM) UVA UVC dose dose Inflow (mJ/ (mJ/ UVA/ Gloss 1/gloss with Exposure cm.sup.2) cm.sup.2) UVC (GU) (1/GU) LM Reference No MSA, 6600 0 >100 130 0.008 − 1 10A Example Nore- 0 0 >100 101 0.010 + 2a exposure Example 10A3Cp 6600 2340 2.8 99 0.010 + 2b Example 10A10Cp 6600 7800 0.8 110 0.009 − 2c

[0091] Table 3 shows the gloss on the surface of the printing plate after 3 days and the inflow of the printing plates after printing with solvent-based ink (LM).

[0092] Without re-exposure (example 2a) or with 10 min of UVA and 3 min of UVC re-exposure (example 2b), a lower gloss value is observed than is the case with 10 min of UVA and 10 min of UVC re-exposure (example 2c). This indicates the presence of MSA on the surface of the floor. In the print test the printing plates from examples 2a and 2b exhibit reduced inflow.

Example 3

[0093] a. An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 2% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). This was exposed from the back for 26 seconds with an intensity of 19 mW/cm.sup.2 in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12/10-R 100W). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 10 minutes with an intensity of 19 mW/cm.sup.2 in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12/10-R 100W). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) and at a rate of 255 mm/min Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 10 minutes and the UVC exposure time was increased from 0 to 10 minutes at intervals of 2 minutes. [0094] b. An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). This was exposed from the back for 14 seconds with an intensity of 19 mW/cm.sup.2 in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12/10-R 100W). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 8 minutes with an intensity of 19 mW/cm.sup.2 in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12/10-R 100W). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) and at a rate of 285 mm/min Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was increased from 0 to 10 minutes at intervals of 2 minutes. [0095] c. An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). This was exposed from the back for 26 seconds with an intensity of 19 mW/cm.sup.2 in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12/10-R 100W). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer in a Next FV exposure unit (Flint Group) by means of the UV LED strip with 3×250 mm/min and an intensity of 800 mW/cm.sup.2. The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) and at a rate of 255 mm/min. Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was increased from 0 to 10 minutes at intervals of 2 minutes.

[0096] Print Parameters: [0097] A solvent-based ink, Flexistar MV Process Cyan (Flint Group), was printed by means of an F&K Flexpress 6S/8 printing machine (Fischer & Krecke) on an LD-PE film (Delo) pretreated with corona on one side and having a width of 400 mm and thickness of 55 μm. A Lohmann 5.3 foam adhesive tape (Lohmann) was used to fasten the printing plates. The anilox roller used was provided with a screen resolution of 420 lines/cm and a volume of 3.5 cm.sup.3/m.sup.2. The print speed was 200 m/min, with a lateral feed of 70 μm for the printing unit and 60 μm for the screen roller. Drying took place in 2 stages at 40° C. and 60° C.

TABLE-US-00004 TABLE 4 Inflow of the printing plate in various ratios of simultaneous UVA to UVC re-exposure UVA exp. UVA exp. UVC UVC Inflow time dose exp. exp. UVA/ with LM Example (min) (mJ/cm.sup.2) time dose UVC ink 3a 10 7200 0 0 >100 + 10 7200 2 1320 5.5 + 10 7200 4 2640 2.7 0 10 7200 6 3960 1.8 0 10 7200 8 5280 1.4 − 10 7200 10 6600 1.1 − 3b 8 5760 0 0 >100 + 8 5760 2 1320 4.4 + 8 5760 4 2640 2.2 0 8 5760 6 3960 1.5 0 8 5760 8 5280 1.1 − 8 5760 10 6600 0.9 − 3c 8 5760 0 0 >100 + 8 5760 2 1320 4.4 + 8 5760 4 2640 2.2 0 8 5760 6 3960 1.5 0 8 5760 8 5280 1.1 − 8 5760 10 6600 0.9 − + = no inflow, 0 = little inflow, − = significant inflow

[0098] Table 4 shows the evaluation of the inflow of the printing plate after printing with solvent-based ink in various ratios of simultaneous UVA to UVC re-exposure. The higher the UVC re-exposure dose applied, i.e. the smaller the ratio of the doses from UVA to UVC re-exposure, the greater the observed inflow of the interstitial spaces of the printing plate. With a moderate UVC re-exposure dose, on the other hand, inflow of the interstitial spaces is largely avoided through migration of the MSA.

Example 4

MSA Migration

[0099] An SIS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). This was exposed from the back for 14 seconds with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 8 minutes with an intensity of 19 mW/cm.sup.2 in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12/10-R 100W). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) and at a rate of 290 mm/min. Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80 W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95 W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time 0 and 2 minutes.

UV-Curing Ink Print Parameters:

[0100] An MO4 printing machine with FA4 flexo units (Nilpeter) was used for printing with the Flexocure Force UV-curing ink (Flint Group). The print medium used was PE-based self-adhesive label material (Raflatac) of width 330 mm and thickness 130 μm or paper-based self-adhesive label material (Raflacoat, UPM) of width 330 mm and thickness 120 μm. A Tesa Blue foam adhesive tape of moderate hardness (Tesa) was used to secure the printing plates. The anilox roller used was provided with a screen resolution of 500 lines/cm and a volume of 2.5 cm.sup.3/m.sup.2. The print speed was 100 m/min

TABLE-US-00005 TABLE 5 Effects of the MSA when printing with UV-curing inks on PE film or paper UVA UVA exp. exp. dose UVC UVC Full-tone Exam- time (mJ/ exp. exp. UVA/ colour Leading ple 4 (min) cm.sup.2) time dose UVC density edges PE 8 5760 0 0 >100 1.40 Not film determined 8 5760 2 1320 4.4 1.34 Not determined Paper 8 5760 0 0 >100 Not No leading determined edges 8 5760 2 1320 4.4 Not Strong determined leading edges

[0101] Table 5 shows the effects of the MSA when printing with UV-curing inks on PE film or paper. With UVC re-exposure, less MSA diffuses onto the surface of the printing plate. When printing on PE film, the absence of MSA resulted in a reduced full-tone colour density being observed; when printing on paper, the occurrence of leading edges. Without UVC re-exposure, the MSA diffuses onto the surface of the printing plate and favours the transfer of ink onto the relevant print medium. When printing on PE film, the presence of MSA resulted in an increase in the full-tone colour density being observed; when printing on paper, the disappearance of the leading edges.

Example 5

[0102] An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 0.1 or 2.5% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). This was exposed from the back for 17 seconds with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 8 minutes with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of Cyrel® Flexosol-i (DuPont) as washout medium and at a rate of 250 mm/min. Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time 2 minutes.

Print Conditions:

[0103] A solvent-based ink, Flexistar MV Process Cyan (Flint Group), was printed by means of an F&K Flexpress 6S/8 printing machine (Fischer & Krecke) on an LD-PE film (Delo) pretreated with corona on one side and having a width of 400 mm and thickness of 55 μm. A Lohmann 5.3 foam adhesive tape (Lohmann) was used to fasten the printing plates. The anilox roller used was provided with a screen resolution of 420 lines/cm and a volume of 3.5 cm.sup.3/m.sup.2. The print speed was 200 m/min

TABLE-US-00006 TABLE 6 UVA UVA UVC UVC MSA exp. exp. exp. exp. conc. time dose time dose UVA/ Example (%) (min) (mJ/cm.sup.2) (min) (mJ/cm.sup.2) UVC Inflow Reference 0 8 5760 2 1320 4.4 −− 5a Example 1 8 5760 2 1320 4.4 + 5b Example 2.5 8 5760 2 1320 4.4 + 5c
Very significant inflow=−−
Significant inflow=−
Moderate inflow=0
Little inflow=+
No inflow=++

[0104] In reference 5a, significant inflow of the plate was observed. The inflow was reduced sharply through the addition of the MSA (examples 5b and 5c (Table 6).

Example 6

[0105] An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.) and 0%; 0.25% or 0.5% of a 1-hydroxycyclohexylphenyl ketone (C1) or 0.5% of a mixture of oxyphenyl acetic acid 2-[2-oxo-2-phenylacetoxy ethoxylethylester and oxyphenyl acetic acid-2-[2-hydroxyethoxylethylester (C2) (each IGM Resins B.V.). This was exposed from the back for 22 seconds with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 10 minutes with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of Cyrel® Flexosol-i (DuPont) as washout medium and at a rate of 250 mm/min. Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time 2 minutes.

Print Conditions:

[0106] A solvent-based ink, Flexistar MV Process Cyan (Flint Group), was printed by means of an F&K Flexpress 6S/8 printing machine (Fischer & Krecke) on an LD-PE film (Delo) pretreated with corona on one side and having a width of 400 mm and thickness of 55 μm. A Lohmann 5.3 foam adhesive tape (Lohmann) was used to fasten the printing plates. The anilox roller used was provided with a screen resolution of 420 lines/cm and a volume of 3.5 cm.sup.3/m.sup.2. The print speed was 200 m/min

TABLE-US-00007 TABLE 7 UVC UVA/ MSA UVC initiator UVC conc. Example initiator conc. (%) initiator (%) Inflow Reference 6a − 0 − 0 −− Example 6b − 0 − 1 0 Example 6c C1 0.05 100 1 + Example 6d C1 0.1  50 1 + Example 6e C1 0.2  25 1 + Example 6f C2 0.5  10 1 +
Very significant inflow=−−
Significant inflow=−
Moderate inflow=0
Little inflow=+
No inflow=++

[0107] Without MSA or a UVC photoinitiator (reference 6a) significant inflow of the plate is observed. The addition of an MSA and a UVC photoinitiator reduces the inflow sharply. With this plate formulation, inflow is also reduced through the addition of 0.5% UVC photoinitiator C2 (Table 7).

Example 7

[0108] An SIS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA, 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.) and 0%, 0.25% or 0.5% of a 1-hydroxycyclohexylphenyl ketone (C1) (IGM Resins B.V.). This was exposed from the back for 14 seconds with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 8 minutes with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of Cyrel® Flexosol-i (DuPont) as washout medium and at a rate of 150 mm/min. Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time 2 minutes.

Print Conditions:

[0109] A solvent-based ink, Flexistar MV Process Cyan (Flint Group), was printed by means of an F&K Flexpress 6S/8 printing machine (Fischer & Krecke) on an LD-PE film (Delo) pretreated with corona on one side and having a width of 400 mm and thickness of 55 μm. A Lohmann 5.3 foam adhesive tape (Lohmann) was used to fasten the printing plates. The anilox roller used was provided with a screen resolution of 420 lines/cm and a volume of 3.5 cm.sup.3/m.sup.2. The print speed was 200 m/min

TABLE-US-00008 TABLE 8 UVC UVA/ MSA initiator C1 UVC conc. Example conc. (%) initiator (%) Inflow Reference 7a 0 − 1 −− Example 7b 0.25 8 1 0 Example 7c 0.5 4 1 +
Very significant inflow=−−

[0110] Significant inflow=−

Moderate inflow=0
Little inflow=+
No inflow=++

[0111] The inflow is reduced by increasing the UVC photoinitiator content while keeping the UVA photoinitiator content the same. With 0.5% UVC photoinitiator (example 7c), hardly any inflow is observed (Table 8).

Example 8

[0112] An SIS-based relief precursor (thickness 1.70 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C., 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.) and 0%, 0.25% or 0.5% of a 1-hydroxycyclohexylphenyl ketone (C1) (IGM Resins B.V.). This was exposed from the back for 40 seconds with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 8 minutes with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) as washout medium and at a rate of 230 mm/min. Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time 4 minutes.

Print Conditions:

[0113] A solvent-based ink, Flexistar MV Process Cyan (Flint Group), was printed by means of an F&K Flexpress 6S/8 printing machine (Fischer & Krecke) on an LD-PE film (Delo) pretreated with corona on one side and having a width of 400 mm and thickness of 55 μm. A Lohmann 5.3 foam adhesive tape (Lohmann) was used to fasten the printing plates. The anilox roller used was provided with a screen resolution of 420 lines/cm and a volume of 3.5 cm.sup.3/m.sup.2. The print speed was 200 m/min.

TABLE-US-00009 TABLE 9 UVC UVA/ MSA initiator C1 UVC conc. Example conc. (%) initiator (%) Inflow Reference 8a 0 − 0 −− Example 8b 0.5 10 1 + Example 8c 1.0 5 1 +
Very significant inflow=−−
Significant inflow=−
Moderate inflow=0
Little inflow=+
No inflow=++

[0114] When compared with reference 8a, the inflow of the plate was reduced sharply through the addition of the MSA and the photoinitiator C1 (examples 8b and 8c). A further increase in the UVC photoinitiator content from 0.5% (example 8b) to 1% (example 8c) does not result in a further improvement with regard to inflow (Table 9).

Example 9

[0115] An SBS-based relief precursor (thickness 1.70 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C., 1% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.) and 0%; 0.5%; 1.0%; 1.5% or 2.0% of 1-(4-methyllphenyl)-1-dodecanon (C3) (BASF). This was exposed from the back for 40 seconds with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through an attached mask layer, fixed by vacuum, for 9 minutes with an intensity of 28 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After removal of the mask layer, the precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of Cyrel® Flexosol-i (DuPont) as washout medium and at a rate of 250 mm/min. Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 10 minutes and the UVC exposure time 5 minutes.

Print Conditions:

[0116] A solvent-based ink, Flexistar MV Process Cyan (Flint Group), was printed by means of an F&K Flexpress 6S/8 printing machine (Fischer & Krecke) on an LD-PE film (Delo) pretreated with corona on one side and having a width of 400 mm and thickness of 55 A Lohmann 5.3 foam adhesive tape (Lohmann) was used to fasten the printing plates. The anilox roller used was provided with a screen resolution of 420 lines/cm and a volume of 3.5 cm.sup.3/m.sup.2. The print speed was 200 m/min.

TABLE-US-00010 TABLE 10 UVC UVA/ initiator C3 UVC MSA Example conc. (%) initiator conc. (%) Inflow Reference 9a 0.0 − 1 −− Example 9b 0.5 2.0 1 0 Example 9c 1.0 1.0 1 + Example 9d 1.5 0.7 1 + Example 9e 2.0 0.5 1 +
Very significant inflow=−−
Significant inflow=−
Moderate inflow=0
Little inflow=+
No inflow=++

[0117] In reference 9a, significant inflow of the plate was observed. The inflow was reduced sharply through the addition of the MSA and the photoinitiator C3 (examples 9b to 9e). From a concentration of 1.0% of the UVC photoinitiator C3 (example 9c) hardly any inflow is observed. The same applies for a further increase in the UVC photoinitiator concentration to 1.5% or 2.0% (examples 9d and 9e) (Table 10).

Example 10

[0118] An SIS-based relief precursor (overall thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C20) having a melting point of 50-57° C. as MSA, 2% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.) and 0% or 0.5% of a 1-hydroxycyclohexylphenyl ketone (IGM Resins B.V.). The relief precursor was exposed from the back for 10 seconds with an intensity of 16 mW/cm.sup.2 in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently exposed through the mask layer for 15 minutes with an intensity of 16 mW/cm.sup.2 at 40° C. in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). The exposed precursor was washed out in a Nyloflex® Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 200 mm/min. Drying took place at 60° C. over 120 minutes. Different re-exposures were then carried out in a Nyloflex® Combi FIII exposure unit, whereby only UVA (Philips TL 60W/10-R, intensity 11 mW/cm.sup.2), only UVC (Philips TUV 75W HO G75 T8, intensity 13 mW/cm.sup.2) or simultaneous UVA and UVC exposures were used, in each case at 40° C. In this context simultaneous means that both exposures (UVA and UVC) were started at the same time. After at least one week of storage following development of the printing plates, contact angle measurements were carried out on the printing surfaces thus formed. The reference used was a surface of pure MSA which was obtained by melting and subsequent cooling.

[0119] The contact angle is a measure of the wetting of the surface. The uniform wetting of the surface with liquid (printing ink) is a fundamental prerequisite for a successful printing process. If wetting is not complete, it will not be possible to transfer the printing forme fully onto the print medium. Wetting is critically determined by the difference between surface tension of the printing ink and the surface energy of the printing plate. A drop of liquid on a surface shows a large contact angle if there is a significant difference between the surface tension of the liquid and the surface energy of the printing plate. If the difference is small, the surface is wet uniformly by the liquid, resulting in a small contact angle. The MSA generates a hydrophobic surface. With polar liquids such as water, for example, a large contact angle is expected.

[0120] Table 11 shows the contact angle of a water drop on printing plates with or without MSA on the surface of the plate. The presence of the MSA is controlled by the re-exposure. The pure MSA serves as reference.

TABLE-US-00011 TABLE 11 UVA UVC Con- % % dose dose tact UVA UVC (mJ/ (mJ/ UVA/ angle Example PI PI Exposure cm.sup.2) cm.sup.2) UVC θ/° Reference 10a — — — — — — 97.9 Example 10b 2 0 10A 6600 0 >100 86.7 Example 10c 2 0 10A10Cp 6600 7800 0.8 78.0 Example 10d 2 1 5C 0 7800 0 89.1 Example 10e 2 1 10A10Cp 6600 7800 0.8 64.1 Example 10f 5 0.5 5C 0 7800 0 97.9 Example 10g 5 0.5 10A10Cp 6600 7800 0.8 84.5

[0121] The presence of the MSA on the surface has an influence on the wetting of the surface with water. If MSA is present on the surface of the printing plate, the contact angle of the water drop is much greater than if no MSA is present on the surface. If MSA is present on the surface of the plate (examples 10b, 10d and 101), the contact angle of the water drop approaches that of the pure MSA (reference 10a). The photoinitiator concentration has a particular effect on the contact angle if there is no MSA present. With 1% UVC PI (example 10e), a smaller contact angle was obtained than without (example 10c). When printing with water-based ink, the presence of the MSA can consequently lead to wetting problems. The migration of the MSA can be controlled through re-exposure.

Example 11

[0122] An SBS-based relief precursor (overall thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C20) having a melting point of 50-57° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). The relief precursor was exposed from the back for 18 seconds with an intensity of 16 mW/cm.sup.2 in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently exposed through the mask layer for 15 minutes with an intensity of 16 mW/cm.sup.2 at 40° C. in a Nyloflex® Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W/10-R). The exposed precursor was washed out in a Nyloflex® Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 220 mm/min Drying took place at 60° C. over 120 minutes. The printing plate was subsequently re-exposed to UVA-light (Philips TL 60W/10-R, intensity 11 mW/cm.sup.2) for 10 min and to UVC light (Philips TUV 75W HO G75 T8, intensity 13 mW/cm.sup.2) for 5 min in a Nyloflex® Combi FIII exposure unit. Both exposures (UVA and UVC) were started at the same time and carried out at 40° C. After at least one week of storage following development of the printing plates, contact angle measurements were carried out on the printing surfaces thus formed. The reference used was a surface of pure MSA which was obtained by melting and subsequent cooling.

TABLE-US-00012 TABLE 12 UVA UVC Con- dose dose tact % (mJ/ (mJ/ UVA/ angle Example MSA Exposure cm.sup.2) cm.sup.2) UVC θ/° Reference 11a 100 — — — — 97.9 Example 11b  1 10A5C 6600 3900 1.7 94.2 Example 11c  0 10A5C 6600 3900 1.7 80.5

[0123] If there is MSA present on the surface of the printing plate (example 11b), the contact angle approaches that on the pure MSA (reference 11a). Without MSA on the surface of the plate (example 11c), a much smaller contact angle is obtained even when the other processing conditions are the same.

Example 12

[0124] An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester carrier with 1% by weight of a paraffin wax (>C35) having a melting point of 58° C. as MSA and 2% by weight of benzil-α,α-dimethyl acetal (IGM Resins B.V.). The plates contained either no MSA or 1% by weight of a paraffin wax (>C35) having a melting point of 58° C., or 0.5% by weight of a polysiloxane polyester acrylate (PPA) as MSA. The relief precursor was exposed from the back for 20 seconds with an intensity of 26 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through the mask layer for 10 minutes with an intensity of 26 mW/cm.sup.2 in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60 W/10-R). The precursor was developed in a Nyloflex® Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) and at a rate of 255 mm/min Drying took place at 60° C. over 120 minutes. Re-exposure then took place at room temperature, with the UVA exposure (Philips TL 80W/10-R SLV G13, intensity 12 mW/cm.sup.2) and UVC exposure (Philips TUV TL-D 95W HO SLV/25, intensity 11 mW/cm.sup.2) being started simultaneously and performed in parallel. The UVA exposure time was 10 minutes and the UVC exposure time 6 minutes.

Print Conditions:

[0125] An MO4 printing machine with FA4 flexo units (Nilpeter) was used for printing with the Flexocure Ancora Process Cyan UV-curing ink (Flint Group). The print medium used was PE-based self-adhesive label material (Raflatac) corona treated on one side or paper-based self-adhesive label material (Raflacoat, UPM) of thickness 120 μm. A Tesa Blue foam adhesive tape of moderate hardness (Tesa) was used to secure the printing plates. The anilox roller used was provided with a screen resolution of 500 lines/cm and a volume of 2.5 cm.sup.3/m.sup.2. The print speed was 100 m/min. The inflow was assessed after about 500 linear metres.

Results:

[0126] Table 13: Inflow of the plate after printing on PE film and paper. Re-exposure used: intensity UVA 7200 mJ/cm.sup.2; UVC=3960 mJ/cm.sup.2. Ratio of UVA/UVC re-exposure intensities=1.8.

TABLE-US-00013 TABLE 13 Concentration Inflow Print MSA/% by with UV- medium MSA weight curing ink PE film No MSA 0 −− Paraffin wax 1 + PPA 0.5 ++ Paper No MSA 0 −− Paraffin wax 1 + PPA 0.5 ++

[0127] Table 13 shows the effect of the MSA on the inflow of the plate when printing with UV-curing ink. Without MSA, significant inflow is observed. The inflow of the block can be reduced sharply by adding a paraffin wax as MSA. A further improvement in the inflow is observed when a polysiloxane polyester acrylate is used as MSA.