Photopolymerizable relief precursors with tunable surface properties

Abstract

The present invention relates to a photopolymerizable relief precursor comprising (A) a dimensionally stable support, and (B) a photopolymerizable relief-forming layer comprising at least a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a migrating surfactant additive, a photoinitiator activatable by UVA light, and a photoinitiator activatable by UVC light. The invention also relates to a method for producing a relief structure.

Description

[0001] The present invention relates to photopolymerizable relief precursors having surface properties that can be adjusted by exposure conditions, a process for producing relief structures from relief precursors, the relief structures themselves and their use.

[0002] Printing with solvent-based inks requires that the printing plate have an ink-repellent surface to prevent ink from flowing into the interstitial spaces between the dots. This is usually achieved by the presence of a surfactant additive (MSA) in the relief layer that can migrate, which reduces the surface tension of the printing surface. However, when printing with UV-curable inks or water-based inks, the presence of such additives can be problematic because it leads to poor ink transfer, for example, in solid areas. Therefore, different printing plates can be used for printing with solvent-based inks, UV-curable inks, or water-based inks. Examples of such printing plates are shown in EP1014194A1, but such printing plates are only suitable for specific types of solvent-based inks.

[0003] The object of the present invention is to provide a printing plate which is "switchable" in such a way that the surface properties of the printing plate can be adjusted by exposure parameters so that the same printing plate can be used universally for different application areas. The requirements imposed on printing plates printed with solvent-based inks differ from those imposed on printing plates printed with UV-curing inks or water-based inks.

[0004] Said object is achieved with a photopolymerizable relief precursor comprising:

[0005] (A) a dimensionally stable carrier,

[0006] (B) A photopolymerizable, relief-forming layer comprising at least a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a surface-active additive capable of migration, a photoinitiator activatable with UVA light, and a photoinitiator activatable with UVC light.

[0007] The relief precursor according to the present invention allows for controlled migration of MSA to the surface by selecting the exposure parameters. It is assumed that MSA is intended to diffuse onto the surface of the relief layer and thus render it hydrophobic. Exposure to UVA light to a greater penetration depth ensures greater crosslinking throughout the relief layer and stabilizes the relief as a whole. Exposure to UVC light results in a lower penetration depth into the photoactive layer and ensures that extensive recrosslinking of monomers and polymers still occurs. Consequently, migration of MSA to the relief surface is reduced or prevented, resulting in a more hydrophilic surface. This, in turn, facilitates wetting of the printed area with hydrophilic printing inks. UVC exposure can also induce oxidation of formulation components, leading to the formation of polar and hydrophilic groups.

[0008] The relief precursor used as a printing plate according to the invention allows to achieve the following advantages, among others:

[0009] The surface properties can be adjusted in such a way that the flow of solvent-based ink into the interstitial spaces between the dots during printing is prevented or reduced. This in turn allows for longer printing times before the plate has to be cleaned.

[0010] The stickiness of a surface and hence the tendency of dust and dirt to accumulate on the surface can be reduced by adjusting the surface properties.

[0011] The same printing plate can be used for printing with different types of printing inks, since the surface properties can be adjusted by choosing the re-exposure conditions in such a way that the printing plate is suitable for printing with solvent-based inks, aqueous inks or UV-curing inks.

[0012] A dimensionally stable carrier material, which may optionally include additional layers, can be used as a dimensionally stable carrier (A). Examples of suitable dimensionally stable carriers are plates, films, and conical and cylindrical sleeves made of metals such as steel, aluminum, copper, or nickel, or of plastics such as polyethylene terephthalate, polybutylene terephthalate, polyamide, or polycarbonate, or of woven or non-woven fabrics such as glass fiber braids, or of composite materials made of glass fiber and plastic. Particularly suitable dimensionally stable carriers are dimensionally stable carrier films or metal sheets, examples being polyethylene films or polyester films, steel sheets, or aluminum sheets. These carrier films generally have a thickness of 50 μm to 1000 μm, preferably 75 μm to 400 μm, for example, about 250 μm. If a plastic film is used, its thickness is in the range of 100 μm to 200 μm, preferably 125 μm to 175 μm. If steel is used as the carrier material, steel sheets with a thickness of 0.05 to 0.3 mm are preferred. To prevent corrosion, tinned steel sheets are preferred. These carrier films or carrier sheets can be coated with a thin adhesion-promoting layer, for example, 0.05 to 5 μm thick, on the side of the carrier film facing the base layer. This adhesive layer can consist, for example, of a mixture of polycarbonate, phenoxy resin, and polyfunctional isocyanate.

[0013] These carrier films or carrier sheets may already be provided with a thin adhesion-promoting layer (AH) or be provided with such a thin adhesion-promoting layer (AH). For the adhesive layer, for example, polyurethane adhesive varnishes based on polyisocyanates (for example according to DE 3045516), crosslinked polyether varnishes or polyester varnishes can be used, with a layer thickness of between 0.5 μm and 50 μm, in particular between 2 μm and 30 μm.

[0014] On the side of the adhesive layer facing away from the carrier layer, there may be further adhesion-promoting intermediate layers (AH). These have a layer thickness of between 0.1 μm and 50 μm, in particular between 1 μm and 10 μm, and can be obtained, for example, from a dilute aqueous-alcoholic solution of partially (for example up to 80 mol %) hydrolyzed polyvinyl ester, phenylglycerol ether monoacrylate and glyoxal by drying and baking.

[0015] The adhesion-promoting layer or intermediate layer is intended to increase the adhesion between the individual layers and stabilize the layer structure. This requires the selection of a material that can interact with the two layers. Preferred examples of such materials are surfactants, amphiphilic molecules and block copolymers having hydrophobic and hydrophilic regions, and oligomers containing blocks that are compatible with the two layers or polymers in the layers. The adhesion between the dimensionally stable support (A) and the relief-forming layer (B) should be greater than 0.5 N / cm when measured in a peel test at a peel angle of 90° and a peel rate of 30 mm / min.

[0016] The relief precursor comprises at least one photopolymerizable relief-forming layer (B). The photopolymerizable relief-forming layer can be applied directly to the support. However, further layers, such as an adhesive layer or an elastic or compressible sublayer, can also be present between the support and the relief-forming layer.

[0017] The relief-forming layer (B) may also consist of more than one layer, in which case it generally comprises 2 to 30 layers, preferably 2 to 5 layers, more preferably 2 to 3 layers, and very preferably 2 layers. The layers may contain the same components or different components, and in the same proportions or different proportions. Preferably, the layers contain the same components. Preferably, the relief-forming layer closest to the support layer has been fixed, crosslinked, and / or reacted. Arranged above these fixed, crosslinked, and / or reacted layers is the relief-forming layer, which may also be fixed, crosslinked, or reacted.

[0018] The skilled artisan is aware of elastomeric binders for producing relief-forming layers of flexographic printing elements. Examples include styrene-diene block copolymers, natural rubber, polybutadiene, polyisoprene, styrene-butadiene rubber, nitrile rubber, butyl rubber, styrene-isoprene rubber, styrene-butadiene-isoprene rubber, polynorbornene rubber, or ethylene-propylene-diene rubber (EPDM). Preference is given to using hydrophobic binders. Such binders are soluble in organic solvents or mixtures thereof.

[0019] Preferably, the elastomer is a thermoplastic elastomer block copolymer of an alkenyl aromatic hydrocarbon and a 1,3-diene. The block copolymers may be linear, branched or radial block copolymers. Typically they are triblock copolymers of the ABA type, but they can also be diblock polymers of the AB type or polymers with more than one alternating elastomeric block and thermoplastic block, such as ABABA. It is also possible to use mixtures of two or more different block copolymers. Commercial triblock copolymers usually contain a certain proportion of diblock copolymers. The diene units may be linked 1,2 or 1,4. Both block copolymers of the styrene-butadiene or styrene-isoprene type and block copolymers of the styrene-butadiene-isoprene type can be used. These are for example known under the names Commercially available. Thermoplastic elastomer block copolymers having terminal styrene blocks and a statistical styrene-butadiene midblock may also be used. Block copolymers may also be fully or partially hydrogenated, such as in SEBS rubber. Preferred elastomeric binders are triblock copolymers of the ABA type or radial block copolymers of the (AB)n type, where A is styrene and B is a diene; as well as statistical and random copolymers of styrene and a diene.

[0020] In a preferred embodiment of the present invention, the thermoplastic elastomer adhesive comprises at least one styrene-isoprene block copolymer, particularly styrene-isoprene-styrene block copolymer, wherein the polymer can also include a certain proportion of diblock styrene-isoprene copolymer. The adhesive of the preferred styrene-isoprene type generally includes 10% to 30% by weight, preferably 12% to 28% by weight and more preferably 13% to 25% by weight of styrene. In another embodiment, the adhesive is a styrene-butadiene-styrene (SBS) block copolymer. The preferred SBS polymer generally includes 20% to 35% by weight, preferably 22% to 33% by weight and more preferably 24% to 31% by weight of styrene. These block copolymers generally have a mean molecular weight MW (weight average) of 100,000 g / mol to 300,000 g / mol. Of course, a mixture of different styrene-isoprene block copolymers or styrene-butadiene block copolymers can also be used.

[0021] In a second embodiment of the present invention, radial isoprene-styrene block copolymers may be preferably used. The isoprene units and / or butadiene units in the polyisoprene blocks may be 1,4-linked, meaning the remaining double bonds are arranged in the chain, or 3,4-linked, meaning the remaining double bonds are arranged sideways. Block copolymers having essentially 1,4 linkages and adhesives having a certain proportion of 3,4 linkages may be used. The side vinyl groups in the adhesives having 3,4-linked units are preferably able to react during the crosslinking process of the photopolymerized layer, thereby producing a sheet with a high degree of crosslinking. For example, block copolymers having a vinyl group content of 20% to 70% may be used.

[0022] In a preferred embodiment of the present invention, radial styrene-isoprene copolymers having a vinyl group content of less than 10% can be used. In a second preferred embodiment of the present invention, a mixture of two different styrene-isoprene block copolymers is used. Preferably, one of them has a vinyl group content of at least 20%, in particular from 20% to 70%, and preferably from 25% to 45%. The other can have a low vinyl group content, for example a vinyl group content of less than 10%. Also preferably, a mixture of two styrene-isoprene copolymers can be used, one of which has a high diblock fraction of more than 40% by weight and the second has a low diblock fraction of less than 30% by weight. In addition to the stated thermoplastic elastomer block copolymers, in particular styrene-isoprene block copolymers, the photopolymerized layer can also contain an additional elastomeric binder different from the block copolymers. Such an additional binder, also referred to as a secondary binder, enables the properties of the photopolymerized layer to be modified. Vinyltoluene-α-methylstyrene copolymer is an example of a secondary binder. Typically, the amount of such secondary binder should not exceed 25% by weight, based on the total amount of all binders used. Preferably, the amount of such secondary binder does not exceed 15% by weight, more preferably does not exceed 10% by weight. The total amount of binder is typically 30% to 90% by weight, preferably 40% to 85% by weight, and more preferably 60% to 85% by weight, based on the sum of all ingredients of the relief-forming layer.

[0023] In the case of the relief precursor that can be developed aqueously, use water-soluble polymer, swellable polymer, dispersible polymer or emulsifiable polymer.Except the polyvinyl acetate of complete or partial hydrolysis, can also use polyvinyl alcohol, polyvinyl acetal, polystyrene sulfonate, polyurethane, polyamide (such as those described in EP 0085472 or in DE 1522444) and any combination thereof.The example of such polymer can be found in EP 0079514, EP0224164 or EP 0059988.These polymers can be straight chain, side chain, star-shaped or dendritic, and exist as homopolymer, statistical copolymer, block copolymer or alternating copolymer.Usually, stated polymer is provided with the functional group that can increase solubility and / or participate in crosslinking reaction.These groups comprise for example carboxyl group, SO Group, OH group, thiol group, ethylenically unsaturated (methyl) acrylate group and epoxy group and any combination thereof.

[0024] In the case of the relief-forming layer (B), the total amount of binder is generally 30 to 90% by weight, preferably 40 to 85% by weight and more preferably 45 to 85% by weight, based on the sum of all ingredients of the relief-forming layer.

[0025] The relief-forming layer (B) may contain additional ingredients selected from the group consisting of plasticizers, solvents, other binders, colorants, stabilizers, regulators, UV absorbers, dispersing aids, crosslinkers, viscosity regulators, surfactants, and any combination thereof. These additives, auxiliaries, and adjuvants are contained in the radiation-sensitive mixture in a total concentration of 0.001% to 60% by weight, preferably 0.01% to 50% by weight, more preferably 0.1% to 50% by weight, and very preferably 1% to 50% by weight, based on the total formulation. Individual additives are contained in a concentration of 0.001% to 40% by weight, preferably 0.01% to 40% by weight, more preferably 0.1% to 40% by weight, and very preferably 0.1% to 35% by weight, based on the total formulation.

[0026] The photopolymerizable relief-forming layer (B) also comprises, in a known manner, at least one ethylenically unsaturated monomer that is compatible with one or more adhesives. The ethylenically unsaturated monomer can also be a mixture of two or more different monomers. Suitable compounds have at least one olefinic double bond and are polymerizable. Therefore, they are referred to below as monomers. Particularly advantageous monomers have been found to be acrylic or methacrylic esters or amides with monofunctional or polyfunctional alcohols, amines, amino alcohols or hydroxy ethers and esters, esters of fumaric or maleic acid, vinyl ethers, vinyl esters and allyl compounds.

[0027] Typically, these monomers are not gaseous compounds at room temperature. Preferably, the ethylenically unsaturated monomers contain at least 2 ethylenically unsaturated groups, more preferably 2 to 10 ethylenically unsaturated groups and very preferably 2 to 6 ethylenically unsaturated groups. Compounds having C—C triple bonds can also be used in the radiation-sensitive mixture. Preferably, the ethylenically unsaturated groups are at least acrylate groups and / or methacrylate groups, but styrene derivatives, acrylamides, vinyl esters and vinyl ethers can also be used. The ethylenically unsaturated monomers have a molecular weight of generally less than 600 g / mol, preferably less than 450 g / mol, more preferably less than 400 g / mol, very preferably less than 350 g / mol and in particular less than 300 g / mol.

[0028] In particular, derivatives of acrylic acid or methacrylic acid may be included, such as their esters with monohydric or polyhydric alcohols, for example acrylic or methacrylic esters of alkanols having 1 to 20 carbon atoms, such as methyl methacrylate, ethyl acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate; (meth)acrylates of polyols having 2 to 20 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,4- ... (meth)acrylates, 3-methylpentanediol di(meth)acrylate, 1,1,1-trimethylolpropane tri(meth)acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol diacrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate or pentaerythritol tetra(meth)acrylate, also poly(ethylene oxide) di(meth)acrylate, meta-methylpoly(ethylene oxide)-yl(meth)acrylate, N,N-diethylaminoethyl acrylate, reaction products from 1 mol of glycerol, 1 mol of epichlorohydrin and 3 mol of acrylic acid; as well as glycidyl methacrylate and bisphenol A diglycidyl ether acrylate.

[0029] Also suitable are derivatives of acrylamide and methacrylamide, such as their N-methylol derivatives and ethers of mono- and polyols, for example ethylene glycol, glycerol, 1,1,1-trimethylolpropane, oligomeric or polymeric ethylene oxide derivatives. These are particularly suitable if polyamides or polyvinyl alcohols are used as binders.

[0030] Also suitable are those known as epoxy (meth)acrylates and urethane (meth)acrylates, such as those obtainable by reaction of bisphenol A diglycidyl ether with (meth)acrylic acid or by reaction of diisocyanates with hydroxyalkyl (meth)acrylates or with polyesters or polyethers containing hydroxyl groups. Other olefinically unsaturated compounds that can be used include esters of acrylic or methacrylic acid, in particular those with low vapor pressure and those modified with compatibilizers, for example with hydroxyl groups, amido groups, sulfonated ester groups or sulfonamide groups. Mixtures of the above-mentioned copolymerizable olefinically unsaturated organic compounds can also be used.

[0031] Preferred ethylenically unsaturated monomers are 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methylpentanediol di(meth)acrylate, 1,1,1-trimethylolpropane tri(meth)acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol diacrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate or pentaerythritol tetra(meth)acrylate.

[0032] In one embodiment, the ethylenically unsaturated monomers are contained in a total concentration in the range of 0.5% to 60% by weight, preferably in the range of 1% to 50% by weight, more preferably in the range of 1% to 40% by weight and very preferably in the range of 2% to 40% by weight, based on the total formulation.

[0033] The photopolymerizable relief-forming layer also contains a surface-active additive capable of migration.

[0034] Preferred surface-active additives capable of migration are selected from the group consisting of: ionic or nonionic surfactants; long-chain hydrocarbons; waxes, in particular paraffin waxes; organosilicon compounds, in particular silicone oils, silanes and siloxanes; or mixtures thereof. Particularly suitable organosilicon compounds are polysiloxane (meth)acrylates, polysiloxane amines, vinyl-terminated polysilanes and polysiloxanes, polyether polysiloxanes and mixtures thereof. Examples of compounds from the above classes are available under the following trade names: Polyvest ST-E 100, Silico Glide T-41, Silico Glide T-57, AFCONA-3700, Silicon F.1000, Silicon F.60000, Rad 2010, Rad 2200N, Rad 2300, Rad 2500, Rad 2700, Rad 2800, Miramer SIU 2400, X-22-2445, X-22-174BX, KBM-5103, X-22-161B, KF-8010, Silmer OH ACR C50, Silmer OH ACR Di-400, Silmer ACR Di-10, Silmer OH ACR D4, AFCONA-3835, and Sartomer CN9800.

[0035] In a preferred embodiment, the surfactant additive capable of migration is a paraffin wax. Branched and / or unbranched paraffin waxes having a chain length of greater than 15 C atoms are preferred, more preferably greater than 20 C atoms and very preferably greater than 30 C atoms. Chain lengths in the region of 20 to 40 C atoms are also preferred.

[0036] The photopolymerizable relief-forming layer further comprises a photoinitiator activatable with UVA light and a photoinitiator activatable with UVC light.

[0037] Preferred photoinitiators activatable with UVA light are selected from the group consisting of benzil ketals, acylphosphine oxides, bisacylphosphine oxides, aminophenyl ketones, phenyloxime esters, and mixtures thereof.

[0038] Preferred photoinitiators activatable with UVC light are selected from the group consisting of hydroxyphenyl ketones, benzoyl formates, benzophenones, aryl alkyl ketones, aryl benzyl ketones and mixtures thereof.

[0039] In a particularly preferred embodiment, the photoinitiator activatable with UVA light is selected from the group consisting of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, benzil dimethyl ketal and benzil diethyl ketal, and the photoinitiator activatable with UVC light is selected from the group consisting of 2-[2-oxo-2-phenylacetoxy-ethoxy]ethyl oxyphenylacetate, 2-[2-hydroxyethoxy]ethyl oxyphenylacetate, methylbenzoylformate, p-tolylundecyl ketone, 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenylpropan-1-one and mixtures thereof.

[0040] The migrating surface active additive is typically contained in the photopolymerized relief-forming layer in an amount of 0.1 to 10% by weight, preferably 0.2 to 5% by weight and more preferably 0.5 to 1.5% by weight, based on the weight of the photopolymerized relief-forming layer.

[0041] Photoinitiators activatable with UVA light are generally contained in the photopolymerized relief-forming layer in an amount of 0.5 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 0.5 to 10% by weight and very preferably 0.5 to 6% by weight, based on the total weight of the photopolymerized relief-forming layer.

[0042] Photoinitiators activatable with UVC light are generally contained in the photopolymerized relief-forming layer in a concentration of 0.1 to 20% by weight, preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight and very preferably 0.25 to 3% by weight, based on the total weight of the photopolymerized relief-forming layer.

[0043] Typically, the mass ratio of photoinitiator activatable with UVA light to photoinitiator activatable with UVC light is from 0.1 to 50, preferably from 0.5 to 40, more preferably from 0.5 to 30 and very preferably from 0.5 to 15.

[0044] Typically, the ratio of the photoinitiator activatable with UVA light to the amount of the surface-active additive capable of migration is from 0.01 to 10, preferably from 0.1 to 5 and more preferably from 0.1 to 3.

[0045] The photopolymerizable relief precursor according to the invention may present one or more further layers selected from the group consisting of an adhesive layer and / or a compressible layer between the support layer and the relief-forming layer, a functional layer arranged above the relief-forming layer, such as a structure-imparting layer, a barrier layer, a cover layer and a digitally reproducible mask layer, and combinations of two or more of these layers.

[0046] For example, the photopolymerizable relief precursor may present an intermediate layer, preferably an adhesive layer and / or a compressible layer, between the support layer and the photopolymerizable relief-forming layer.

[0047] The photopolymerizable relief precursor may present a further layer selected from the group consisting of a mask layer, a barrier layer, a cover layer and a combination of two or more of these layers on the side of the photopolymerizable relief-forming layer facing away from the support layer.

[0048] In a preferred embodiment, the photopolymerizable relief precursor comprises:

[0049] (A) Dimensionally stable carrier;

[0050] (AH) optionally an adhesion promoting layer;

[0051] (B) a photopolymerizable, relief-forming layer comprising at least a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a surface-active additive capable of migration, a photoinitiator activatable with UVA light, and a photoinitiator activatable with UVC light;

[0052] (C) a laser ablatable mask layer comprising at least a non-radical cross-linkable elastomeric polymer, a UVA light absorbing material, and an IR light absorbing material; and optionally

[0053] (D) A cover layer that can be peeled off.

[0054] The relief precursor according to the invention preferably comprises a laser-ablatable mask layer (C), which is arranged above the relief-forming layer (B) and can also be removed using solvents or by heating and adsorption / absorption. This layer is heated and volatilized by selective irradiation with high-energy electromagnetic radiation, thereby generating a mask with image-wise structuring, which is used to transfer the structure to the relief precursor. To this end, it must be impermeable in the UV range and must absorb radiation in the VIS-IR range, resulting in heating and ablation of the layer.

[0055] The optical density of the mask layer in the UV range of 330 nm to 420 nm is in the range of 1 to 5, more preferably in the range of 1.5 to 4 and very preferably in the range of 2 to 4. The optical density is determined by measurement with an X-rite 361TX densitometer in the "density" setting with a UV filter.

[0056] The layer thickness M of the laser-ablatable mask layer (C) is typically 0.1 μm to 5 μm. If the layer thickness is below 0.1 μm, it is difficult to achieve a sufficient optical density. If the layer thickness is greater than 5 μm, the laser sensitivity of the element is too low, so that a long laser time is required for imaging. The layer thickness is preferably 0.3 μm to 4 μm, in particular 1 μm to 3 μm. The laser sensitivity of the mask layer (in order to ablate 1 cm) is required to be 0.1 μm to 5 μm. 2 The energy of the layer should be within 0.1J / cm 2 and 10J / cm 2 between, preferably between 0.3 J / cm 2 and 5J / cm 2 between and more preferably between 0.5 J / cm 2 and 5J / cm 2 between.

[0057] The mask layer (C) comprises at least one non-radical crosslinkable elastomeric polymer that is capable of evenly distributing the components that absorb electromagnetic radiation and ablating as efficiently as possible when heated. The elastomeric polymer can be a linear, branched, star-shaped, comb-shaped or dendritic homopolymer or copolymer. The copolymer can be present as a statistical copolymer and / or a block copolymer. The elastomeric polymer can also be a mixture of different polymers that differ, for example, in structure, monomer composition, block length, molecular weight, functional groups, their number and / or distribution. Mixtures of polymers can also be used.

[0058] Examples of very suitable non-radical crosslinkable elastic polymers for the mask layer (C) include ethylene vinyl acetate, flexible elastic polyamides, flexible elastic polyurethanes, nitrocellulose, polyvinyl acetals such as poly(vinyl butyral-vinyl alcohol) copolymers (or poly(vinyl butyral vinyl acetal-vinyl alcohol) copolymers). Other flexible elastic materials can of course also be used as binders, such as, for example, partially hydrolyzed polyvinyl acetate. Preferred binders for the mask layer (C) are flexible elastic polyamides, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate or partially hydrolyzed polyvinyl acetals.

[0059] The masking layer (C) may be permeable or impermeable to oxygen.

[0060] Typically, the relief-forming layer (B) and the ablatable mask layer (C) are soluble in common, commercially available washout media, which typically consist of a solvent mixture or an aqueous solution. These washout media consist of one or more non-polar hydrocarbon solvents as a major component, with minor components being in the form of moderately polar alcohols such as benzyl alcohol, n-pentanol, cyclohexanol, ethylhexanol, or heptanol. The aqueous solutions typically contain surfactants and / or flocculants and typically have a pH > 7. The relief-forming layer (C) can be processed in these washout media for conventional times.

[0061] Furthermore, the relief-forming layer (B) and the ablatable mask layer (C) can also be developed or removed thermally (see, for example, EP 1 239 329 or EP 1 170 121). In this case, after image-wise exposure, the relief structure is heated to a softening or melting temperature. This renders the unexposed and uncrosslinked areas of the relief structure partially liquid and viscous, and these are then removed continuously by absorbing (absorption) with a nonwoven or woven fabric.

[0062] In a further embodiment, a further layer (E) is present between layer (B) and layer (C) in the relief precursor according to the invention, which further layer (E) is impermeable to oxygen. If an oxygen-impermeable layer (E) is present, layer (B) and / or layer (C) is preferably permeable to oxygen. The layer thickness of layer (E) here is in the range from 3 μm to 5 μm. In addition to the adjuvant, the layer predominantly comprises one or more elastic polymers with a low oxygen permeability, the oxygen permeability of the elastic polymer being less than or equal to 1.5*10 5 cm 3 *μm / (m 2 The polymer in layer (E) is preferably likewise non-free-radically crosslinkable.

[0063] Examples of suitable elastomeric polymers that are heat-developable and / or soluble in organic solvents and have a sufficient barrier effect against oxygen include partially hydrolyzed polyvinyl acetate, ethylene-vinyl acetate copolymers, and ethylene-vinyl alcohol copolymers, with a degree of hydrolysis ranging from 30 mol % up to a maximum of 80 mol %. Also highly suitable are cyclic acetals of polyvinyl alcohol, such as polyvinyl butyral, polyvinyl acetal, polyvinyl formal, and polyvinyl propionate, as well as copolymers containing two or more different vinyl acetal units selected from the group consisting of vinyl formal, vinyl acetal, vinyl propionate, and vinyl butyral. Polyvinyl acetals are typically copolymers containing vinyl alcohol units, since the reaction of polyvinyl alcohol with a fully formed acetal is incomplete for statistical and steric reasons. Therefore, poly(vinyl butyral) is, strictly speaking, a poly(vinyl butyral-vinyl alcohol). The residual OH content of the polyvinyl acetals mentioned is typically between 10% and 30% by weight. For example, vinyl acetal-vinyl butyral-vinyl alcohol copolymer (poly(vinyl acetal-vinyl butyral)) is very suitable.

[0064] The present invention also relates to a method for producing a relief structure, comprising the following steps:

[0065] (i) providing a photopolymerizable relief precursor comprising at least one surface-active additive capable of migrating,

[0066] (ii) applying a mask or producing a structured masking layer over the photopolymerizable relief-forming layer,

[0067] (iii) optionally exposing the back side to electromagnetic radiation through the carrier layer,

[0068] (iv-a) exposing the photopolymerized relief-forming layer to electromagnetic radiation, preferably in the wavelength range from 315 nm to 380 nm, through a mask or a mask layer,

[0069] (v) removing the mask or mask layer, any further layers that may be present and the non-photopolymerized areas of the relief-forming layer that were not exposed in step (iv), thereby producing a relief,

[0070] (vi) optional drying of the relief,

[0071] (vii) re-exposing the relief from the side facing away from the support layer to UVA light in the wavelength range from 315 nm to 380 nm and / or UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is re-crosslinked and the permeability of the relief to migrating surface-active additives is adjusted for adjusting the surface properties of the relief, preferably for use in specific printing inks,

[0072] (viii) optionally further processing steps.

[0073] The present invention further provides a method for producing a relief structure, comprising the following steps:

[0074] (i) providing a photopolymerizable relief precursor comprising at least one surface-active additive capable of migrating,

[0075] (iii) optionally exposing the back side to electromagnetic radiation through the carrier layer,

[0076] (iv-b) imagewise exposing the photopolymerized relief-forming layer to electromagnetic radiation, preferably in the wavelength range from 315 nm to 380 nm,

[0077] (v) removing any further layers that may be present and the non-photopolymerized areas of the relief-forming layer that were not exposed in step (iv), thereby producing a relief,

[0078] (vi) optional drying of the relief,

[0079] (vii) re-exposing the relief from the side facing away from the support layer to UVA light in the wavelength range from 315 nm to 380 nm and / or UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is re-crosslinked and the permeability of the relief to migrating surface-active additives is adjusted for adjusting the surface properties of the relief, preferably for use in specific printing inks,

[0080] (viii) optionally further processing steps.

[0081] In a preferred embodiment, the re-exposure in step (vii) occurs with UVA light and UVC light. The re-exposure to UVA light and UVC light may occur simultaneously (concurrently) or in alternation (alternatingly).

[0082] In the case of re-exposure to UVA light, this is typically in the range of 100 mJ / cm 2 Up to 30,000mJ / cm 2 The dose of UVA light was 100mJ / cm 2 Up to 20,000mJ / cm 2 UVA light is preferred, 100mJ / cm 2 Up to 7,000mJ / cm 2 UVA light is more preferred, and 500mJ / cm 2 Up to 7,000mJ / cm 2 UVA light is highly preferred.

[0083] In the case of re-exposure to UVC light, this typically ranges from 100 mJ / cm 2 Up to 20,000mJ / cm 2 The dose of UVC light was 100mJ / cm 2 Up to 20,000mJ / cm 2 UVC light is preferred, 100mJ / cm 2 Up to 8,000mJ / cm 2 UVC light is more preferred, and 500mJ / cm 2 Up to 8,000mJ / cm 2 UVC light is highly preferred.

[0084] The re-exposure to UVA light and UVC light can occur simultaneously, sequentially or alternately, wherein the dose ratio of UVA light to UVC light (D UVA / D UVC ) is generally greater than 0.2, preferably greater than 0.4, more preferably greater than 0.6 and very preferably greater than 0.8. While exposure to UVC light preferably seals the surface of the layer due to the lower penetration depth, exposure to UVA light ensures stronger crosslinking of the entire layer, so that a mechanically stable relief is obtained.

[0085] In a first step (i), a relief precursor as previously described is provided. It may optionally be cleaned, in which case all techniques familiar to the skilled person may be used, such as, for example, brushing, blowing off, wiping (with and without solvent), rinsing and any desired combination thereof.

[0086] The wavelength of the irradiating electromagnetic radiation is in the range of from 200nm to 2,000nm, preferably in the UV range, more preferably in the range of from 200nm to 550nm, very preferably in the range of from 300nm to 450nm. In addition to broadband irradiation of electromagnetic waves, it may be advantageous to use narrowband or monochromatic wavelength ranges that can be generated using corresponding filters, lasers or light emitting diodes (LEDs). In these cases, preferred wavelengths are in the range of 350nm, 365nm, 385nm, 395nm, 400nm, 405nm, 532nm, 830nm, 1064nm, either individually (and higher and / or lower by about 5nm-10nm) or in combination.

[0087] In case a covering layer (D) is present, it is removed. Preferably, the covering layer is a protective film and is peeled off.

[0088] In step (ii), the mask layer is imaged by removing the layer and / or by locally resolving changes in the absorption and / or reflection properties in such a way that the mask layer becomes at least partially transparent in the wavelength range used for imaging. The mask layer is preferably ablated using a high-energy laser, wherein the laser beam is directed over the mask layer under computer control. In this case, IR lasers with wavelengths in the range of 500 nm to 20,000 nm, preferably in the range of 800 nm to 10,000 nm, and more preferably in the range of 1,000 nm to 2,000 nm are primarily used. Wavelengths of approximately 830 nm, 980 nm, 1064 nm, and 10.6 μm, or combinations thereof, are particularly preferred.

[0089] In an optional step (iii), the relief precursor can be extensively irradiated with electromagnetic radiation from at least one side. This irradiation preferably occurs from the side of the relief precursor opposite the mask layer in order to achieve anchoring of the relief structure to be produced (rear exposure). This rear exposure preferably occurs via a transparent, dimensionally stable material as a support material, such as, for example, a polymer film, and in particular a polyester film. In the case of a non-transparent support material, step (iii) is omitted.

[0090] In step (iv-a), the exposure of the relief precursor according to the invention to electromagnetic radiation, which passes through layer (C) and optionally layer (E), triggers a reaction in those areas of layer (B) situated below the exposed areas of layer (C), which results in crosslinking of the components present in the layers. As a result of this crosslinking, these areas are stable and cannot be removed in a subsequent development step. The irradiation is usually extensive, but can alternatively be carried out on small areas (vertical spot) by means of a directed laser beam or positionally resolved projection of electromagnetic radiation. The electromagnetic radiation used for this exposure generally has a wavelength in the range of 200 nm to 2,000 nm, preferably in the range of 315 nm to 380 nm.

[0091] Here, the irradiation can take place continuously or in pulsed form or in more than one short period with continuous irradiation. The intensity of the irradiation can be varied within a wide range, ensuring that a dose sufficient to crosslink layer (B) for the subsequent development process is used. The intensity of the irradiation is generally in the range of 10 mW / cm 2 Up to 1,000mW / cm 2 The radiation dose is usually in the range of 3J / cm 2 Up to 100J / cm 2 In the range of 6 J / cm 2 Up to 20J / cm 2The exposure to the energy source can also be carried out in an inert atmosphere, such as, for example, in a noble gas, CO 2 and / or nitrogen, or under a liquid which does not damage the multilayer element.

[0092] Direct image-wise exposure can be achieved by selectively exposing the areas to be crosslinked. This can be achieved, for example, with one or more laser beams (the laser beams are controlled accordingly), by using a screen (certain pixels emitting radiation are activated on the screen), by using a moving LED strip (using an LED array in which individual LEDs are intentionally switched on and off), by using an electronically controllable mask (in which pixels that allow the radiation from the radiation source to pass through become transparent), by using a projection system (in which pixels are exposed to radiation from the radiation source by corresponding alignment of mirrors), or a combination thereof. Direct exposure with the aid of a controlled laser beam or a projection system with mirrors is preferred. Here, the absorption spectrum of the initiator or initiator system and the emission spectrum of the radiation source must at least partially overlap.

[0093] In step (v), the uncrosslinked areas of layer (C) and, if present, layer (E) and also layer (B) are removed, thereby producing the relief. In step (v), the unexposed, non-photopolymerized areas of the relief-forming layer can be removed by treatment with a washout medium or by heat treatment.

[0094] The layers can be removed individually or in groups or all together and simultaneously. Preferably, all layers and the uncrosslinked regions of (B) are removed in a single step. Depending on the nature of the layers, this can be achieved by treatment with a solvent-based or water-based rinse medium, such as, for example, an organic solvent, a mixture thereof, water, an aqueous solution or a water-organic solvent mixture, which is capable of dissolving, emulsifying and / or dispersing the uncrosslinked regions of layer (B).

[0095] In another embodiment, the removal of the uncrosslinked areas of layer (C) and (if present) layer (E) and also layer (B) in step (v) occurs thermally, in other words, by introducing heat and removing the softened or partially liquefied material of the layers. The heating of the exposed relief precursor can be carried out by all techniques known to the skilled person, such as, for example, irradiation with IR light, the action of hot gases (e.g., air), the use of heated rollers, or any desired combination thereof. To remove the (viscous) liquid areas, all techniques and processes familiar to the skilled person can be used, such as, for example, blowing, suction, dabbing, spraying (with particles and / or droplets), peeling, wiping, transfer to a developer medium, and any desired combination thereof. Preferably, the liquid material is absorbed (absorbed and / or adsorbed) by the developer medium, which is in continuous contact with the heated surface of the relief precursor. This procedure is repeated until the desired relief height is reached. Developer media that can be used are paper, woven and non-woven fabrics, and films, which are capable of absorbing the liquefied material and can consist of natural fibers and / or polymer fibers. Preference is given to using nonwovens or nonwoven fiber webs of polymers such as cellulose, cotton, polyester, polyamide, polyurethane, and any desired combination thereof, which are stable at the temperatures used when developing.

[0096] The present invention also relates to a method for producing an optimized relief structure, wherein the method is carried out a plurality of times through steps (i) to (viii), wherein in step (vii), the re-exposure to UVA light and / or UVC light is varied according to the dose and / or time sequence of the UVA and UVC re-exposure steps in order to optimize the surface properties of the relief.

[0097] The present invention also relates to a relief structure obtainable according to the method described above and its use. The relief structure can be used as a pad, flexible plate, relief printing plate, gravure plate, microfluidic component, microreactor, electrochemical cell, photonic crystal, or optical component. In the case of a microfluidic component or microreactor, it may be advantageous to render the surface hydrophobic when using aqueous fluids or very polar fluids, in order to reduce interaction with the wall when using non-polar fluids, or to create a hydrophilic surface. In the case of an electrochemical cell, photonic crystal, or optical component, rendering the surface hydrophobic or hydrophilic, respectively, may be advantageous with regard to contamination and cleaning.

[0098] The present invention is illustrated in more detail by the following examples. Example

[0099] method:

[0100] Assessment of inflow

[0101] To evaluate inflow, the plates were evaluated after approximately 1,000 linear meters of printing by evaluating the tonal value field from 10% to 50%. Heavy inflow (a lot of ink in the interstitial spaces) was classified as "-", moderate inflow as "0", and little to no inflow (no ink in the interstitial spaces) as "+".

[0102] Methods for gloss measurement

[0103] Gloss measurements were performed to provide evidence of migrating surfactant additives (MSAs) on the panels' surfaces. Gloss was measured using a micro-TRI-gloss μ glossmeter (BYK–Gardner GmbH) at a 60° glancing angle. Prior to measurement, the glossmeter was calibrated using a synthetic calibration standard. The result was the average of three measurements at each different point on the panel's surface. Removing the MSA by cleaning the surface with a solvent resulted in an increase in gloss to 40-50 GU.

[0104] Figures 1 to 3 The development of gloss in gloss units (GU) as a function of time in days is shown for different re-exposure times.

[0105] Methods for IR measurements

[0106] FT-IR measurements were performed to provide evidence of 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 to perform FT-IR measurements on the surface of the plate. Data were captured and analyzed with the aid of Opus software version 7.5 (Bruker). Background correction of the spectra was performed automatically. -1 and 729cm -1 The integration of the IR bands at 1730 cm-1 was used as a measure of the presence of MSA. For this purpose, they were integrated relative to the IR band at 1730 cm-1. -1 The integration of the IR bands was normalized and then zero value (result without MSA) was subtracted. The signal attributable to MSA was determined by IR spectroscopy of the pure substance. After removing MSA by cleaning the surface with a solvent, the signal attributable to MSA in the IR spectrum was no longer visible.

[0107] Figures 4 to 6 Shows that for a given number of re-exposures, the -1 and 729cm -1 The integral of the IR band at .

[0108] Methods for contact angle measurements

[0109] The effect of MSA on the wettability of surfaces with water was investigated using contact angle measurements. For this purpose, a 10 μL drop of demineralized water was placed on the surface of the printed plate. The droplet profile was captured using a Keyence VHX-500F optical microscope using a VH-Z20R lens and a VH-S30 tripod. The droplet radius, r, and height, h, were measured from these captures using the associated software. The contact angle, θ, was calculated using the trigonometric method (Equation 1).

[0110]

[0111] Example 1:

[0112] A SBS-based relief precursor (total thickness 1.14 mm) was produced on a polyester support 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-dimethylacetal (IGM resin BV). The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 The relief precursor was exposed from the back for 25 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently in a The exposure was carried out in a Combi FIII exposure unit (Flint Group) at 40°C with the aid of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 The intensity of the exposure through the mask layer lasts for 15 minutes. The exposed precursor was washed out in a Digital Washer FIII (Flint Group) with the aid of nylosolv A at a rate of 220 mm / min. Drying took place at 60° C. within 120 minutes. Different re-exposures were performed in a Combi FIII exposure unit, where no exposure was used, only UVA (Philips TL 60W / 10-R, intensity 11 mW / cm 2 ) exposure, using only UVC (Philips TUV 75W HO G75 T8, intensity 13mW / cm 2) exposure, using continuous and simultaneous UVA and UVC exposure, in each case at 40°C. Simultaneous in this context means that both exposures (UVA and UVC) began at the same time. IR and gloss measurements were then taken at certain time intervals on the printed surface thus formed. The reference did not contain any MSA. 1A means an additional exposure to UVA light for 1 minute, and 1C means an additional exposure to UVC light for 1 minute.

[0113] Figure 1 、 Figure 2 and Figure 3 The gloss value decreases as the MSA diffuses onto the surface. Figure 4 、 Figure 5 and Figure 6 When compared, it can be seen that the decrease in gloss value is associated with the increase in IR signal. Figure 1 ), no significant effect of UVA re-exposure time on MSA migration could be discerned. Figure 2 ), the amount of MSA decreased dramatically with increasing re-exposure time. The effect of re-exposure to UVC on MSA migration was felt most strongly when combined with re-exposure to UVA for 10 min. In the case of exposure to UVA for 10 min and re-exposure to UVC for 10 min, much less MSA reached the printed surface than in the case of re-exposure to UVA for 10 min without UVC exposure ( Figure 3 ). Thus the properties of the printed surface can be controlled.

[0114] Table 1: IR integral and gloss on printed surface after 2 days

[0115]

[0116] Table 1 shows the IR integral and glossiness of the printed surface after two days as a function of re-exposure conditions. The greater the IR integral value, the more MSA is present on the plate surface. The IR integral is related to the inverse of glossiness. Low glossiness is evidence of the presence of MSA on the surface. In the absence of MSA, no MSA can be detected by IR spectroscopy. When exposed to UVA for 10 minutes and then exposed to UVC for 10 minutes, much less MSA reaches the printed surface compared to no re-exposure or re-exposure to UVA for 10 minutes without UVC exposure. This allows for control of the properties of the printed surface.

[0117] Table 2: IR integral and gloss on printed surface after 7 days

[0118]

[0119] Table 2 shows the effects of UVA and UVC exposure on the presence of MSA on the plate surface. A duration of 7 days was chosen to verify that MSA had not actually reached the surface. Reference 1 shows the values ​​produced without MSA. Less UVA and UVC light were applied to the printing plate with MSA, resulting in more MSA on the surface after 7 days. The impact of UVC light was greater than that of UVA light. The values ​​obtained for the combined UVA and UVC exposure correspond to those for the printing plate without MSA.

[0120] Example 2:

[0121] a) A SIS-based relief precursor (thickness 1.14 mm) was produced on a polyester support 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 resin BV) and 0.5% by weight of 1-hydroxycyclohexyl phenyl ketone (IGM resin BV).

[0122] b) A second relief precursor, but without 1-hydroxycyclohexylphenyl ketone, produced likewise according to a).

[0123] exist The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL80W / 10-R) at 16 mW / cm 2 The two plate types were exposed from the back for 15 seconds (a) and 10 seconds (b) at an intensity of 100 nm. After the protective film was peeled off, the precursors were imaged in a ThermoFlexX 20 (Xeikon) and subsequently in a The exposure was carried out in a CombiFIII exposure unit (Flint Group) at 40°C with the aid of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 The intensity of the exposure through the mask layer lasts for 15 minutes. The precursor was washed out in a Digital Washer FIII (Flint Group) with the aid of nylosolv A at a rate of 200 mm / min. Drying took place at 60° C. within 120 minutes. Different re-exposures were carried out at 40°C in a Combi FIII exposure unit, where UVA and UVC exposures were used in parallel and started simultaneously. In the former case, there was a 2 10 minutes of UVA exposure (Philips TL 60W / 10-R) with an intensity of 13mW / cm2 In one embodiment, the UVA exposure was 10 minutes and the UVC exposure was 10 minutes. The gloss was then measured at regular time intervals on the non-printed area (bottom plate) thus formed.

[0124] Table 3: Gloss after 3 days and flow into the printing plate with solvent-based inks (LM)

[0125]

[0126] Table 3 shows the glossiness on the surface of the printed plates after 3 days and the flow-in of the printed plates after printing with solvent-based inks (LM).

[0127] In the absence of re-exposure (Example 2a) or in the case of 10 minutes of UVA and 3 minutes of UVC re-exposure (Example 2b), the observed gloss values ​​were lower than in the case of 10 minutes of UVA and 10 minutes of UVC re-exposure (Example 2c). This indicates the presence of MSA on the surface of the substrate. In the printing test, the printing plates from Example 2a and Example 2b showed reduced inflow.

[0128] Example 3:

[0129] a. A SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support with 1% by weight of paraffin wax (>C35) having a melting point of 58° C. as MSA and 2% by weight of benzil-α,α-dimethyl acetal (IGM resin BV). The exposure was carried out in a Next FV exposure unit (Flint Group) with the aid of a fluorescent tube (Light EmissionTech F100T12 / 10-R 100W) at 19 mW / cm 2 The relief precursor was exposed from the back for 26 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Next FV exposure unit (Flint Group) with the aid of a fluorescent tube (Light Emission Tech F100T12 / 10-R 100 W) at 19 mW / cm 2 The intensity of the exposure through the mask layer lasts for 10 minutes. The precursor was developed in a Flowline Washer FV (Flint Group) with the aid of nylosolv A (Flint Group) at a rate of 255 mm / min. Drying took place at 60° C. over 120 minutes. Further exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 10 minutes, and the UVC exposure time was increased from 0 minutes to 10 minutes at intervals of 2 minutes.

[0130] b. A SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support with 1% by weight of paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM resin BV). The exposure was carried out in a Next FV exposure unit (Flint Group) with the aid of a fluorescent tube (Light EmissionTech F100T12 / 10-R 100W) at 19 mW / cm 2 The relief precursor was exposed from the back for 14 seconds at an intensity of 1.5 Å. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Next FV exposure unit (Flint Group) with the aid of a fluorescent tube (Light Emission Tech F100T12 / 10-R 100 W) at 19 mW / cm 2 The intensity of the exposure is continued through the mask layer for 8 minutes. The precursor was developed in a Flowline Washer FV (Flint Group) with the aid of nylosolv A (Flint Group) at a rate of 285 mm / min. Drying took place at 60° C. over 120 minutes. Further exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 8 minutes, and the UVC exposure time was increased from 0 minutes to 10 minutes at intervals of 2 minutes.

[0131] c. A SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support with 1% by weight of paraffin wax (>C35) having a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM resin BV). The exposure was carried out in a Next FV exposure unit (Flint Group) with the aid of a fluorescent tube (Light EmissionTech F100T12 / 10-R 100W) at 19 mW / cm 2 The relief precursor was exposed from the back for 26 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Next FV exposure unit (Flint Group) with the aid of a UV LED strip at 3×250 mm / min and 800 mW / cm 2 The intensity is exposed through the mask layer. The precursor was developed in a Flowline Washer FV (Flint Group) with the aid of nylosolv A (Flint Group) at a rate of 255 mm / min. Drying took place at 60° C. over 120 minutes. Further exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 8 minutes, and the UVC exposure time was increased from 0 minutes to 10 minutes at intervals of 2 minutes.

[0132] Printing parameters:

[0133] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on an LD-PE film (Delo) that was corona pretreated on one side and had a width of 400 mm and a thickness of 55 μm using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The anilox roller used was set with a screen resolution of 420 lines / cm and a 3.5 cm 3 / m 2 The printing speed was 200 m / min, with an infeed of 70 μm for the printing unit and 60 μm for the screen roller. Drying took place in two stages at 40° C. and 60° C.

[0134] Table 4: Influx of printed plates at various ratios of simultaneous UVA and UVC re-exposure

[0135]

[0136]

[0137] + = no inflow, 0 = small inflow, - = large inflow

[0138] Table 4 shows an evaluation of influx into printed plates after printing with solvent-based inks at various ratios of simultaneous UVA and UVC re-exposure. The higher the applied UVC re-exposure dose, i.e., the smaller the ratio of UVA to UVC re-exposure dose, the greater the observed influx into the interstitial spaces of the printed plate. On the other hand, at moderate UVC re-exposure doses, influx into the interstitial spaces was largely avoided by migration of MSA.

[0139] Example 4:

[0140] MSA Migration

[0141] A SIS-based relief precursor (thickness 1.14 mm) was produced on a polyester support 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 resin BV). The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The relief precursor was exposed from the back for 14 seconds at an intensity of 1.5 Å. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Next FV exposure unit (Flint Group) with the aid of a fluorescent tube (Light Emission Tech F100T12 / 10-R 100 W) at 19 mW / cm 2 The intensity of the exposure is continued through the mask layer for 8 minutes. The precursor was developed in a Flowline Washer FV (Flint Group) with the aid of nylosolv A (Flint Group) at a rate of 290 mm / min. Drying took place at 60° C. over 120 minutes. Further exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUVTL-D 95W HO SLV / 25, intensity 11mW / cm 2) were started simultaneously and performed in parallel. The UVA exposure time was 8 minutes, and the UVC exposure times were 0 minutes and 2 minutes.

[0142] UV curing ink printing parameters:

[0143] For printing with Flexocure Force UV curing ink (Flint Group), an MO4 printing press (Nilpeter) with an FA4 flexographic printing unit was used. The printing media used were PE-based self-adhesive label stock (Raflatac) with a width of 330 mm and a thickness of 130 μm or paper-based self-adhesive label stock (Raflacoat, UPM) with a width of 330 mm and a thickness of 120 μm. Medium-hard Tesa blue foam tape (Tesa) was used to secure the printing plates. The anilox roller used was set with a screen resolution of 500 lines / cm and a 2.5 cm 3 / m 2 The printing speed is 100m / min.

[0144] Table 5: Effect of MSA on PE film or paper when printed with UV curable inks

[0145]

[0146] Table 5 shows the effect of MSA on PE film or paper when printing with UV-curable inks. With UVC re-exposure, less MSA diffuses onto the surface of the printing plate. The absence of MSA results in a reduced observed full-tone color density when printing on PE film and the appearance of a leading edge when printing on paper. Without UVC re-exposure, MSA diffuses onto the surface of the printing plate and facilitates ink transfer to the associated print medium. The presence of MSA results in an increase in observed full-tone color density when printing on PE film and the disappearance of a leading edge when printing on paper.

[0147] Example 5:

[0148] An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support 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 resin BV). The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2The relief precursor was exposed from the back with an intensity of 100 nm for 17 seconds. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The intensity of the exposure is continued through the mask layer for 8 minutes. Flowline Washer FV (Flint Group) Flexosol-i (DuPont) was used as the washout medium and the precursor was developed at a rate of 250 mm / min. Drying took place at 60° C. within 120 minutes. Re-exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was 2 minutes.

[0149] Printing conditions:

[0150] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on an LD-PE film (Delo) that was corona pretreated on one side and had a width of 400 mm and a thickness of 55 μm using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The anilox roller used had a screen resolution of 420 lines / cm and a 3.5 cm 3 / m 2 The printing speed is 200m / min.

[0151] Table 6:

[0152]

[0153] Very large inflow =--

[0154] Large inflow = -

[0155] Medium inflow = 0

[0156] Small inflow = +

[0157] No inflow =++

[0158] In reference 5a, a large influx of the plate was observed. By adding MSA, the influx was drastically reduced (Example 5b and Example 5c (Table 6)).

[0159] Example 6:

[0160] An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support having 1% by weight of a paraffin wax (>C35) with a melting point of 58° C. as MSA and 5% by weight of benzil-α,α-dimethyl acetal (IGM resin BV) and a mixture of 0%, 0.25% or 0.5% of 1-hydroxycyclohexyl phenyl ketone (C1) or 0.5% of 2-[2-oxo-2-phenylacetoxyethoxy]ethyl oxyphenylacetate and 2-[2-hydroxyethoxy]ethyl oxyphenylacetate (C2), each IGM resin BV. The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The relief precursor was exposed from the back for 22 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The intensity of the exposure through the mask layer lasts for 10 minutes. Flowline Washer FV (Flint Group) Flexosol-i (DuPont) was used as the washout medium and the precursor was developed at a rate of 250 mm / min. Drying took place at 60° C. within 120 minutes. Re-exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was 2 minutes.

[0161] Printing conditions:

[0162] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on an LD-PE film (Delo) that was corona pretreated on one side and had a width of 400 mm and a thickness of 55 μm using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The anilox roller used had a screen resolution of 420 lines / cm and a 3.5 cm 3 / m 2 The printing speed is 200m / min.

[0163] Table 7:

[0164]

[0165] Very large inflow =--

[0166] Large inflow = -

[0167] Medium inflow = 0

[0168] Small inflow = +

[0169] No inflow =++

[0170] In the absence of MSA or UVC photoinitiator (reference 6a), a large influx of the plate was observed. The addition of MSA and UVC photoinitiator drastically reduced the influx. In the case of this plate formulation, the influx was also reduced by adding 0.5% of UVC photoinitiator C2 (Table 7).

[0171] Example 7:

[0172] A SIS-based relief precursor (thickness 1.14 mm) was produced on a polyester support containing 1% by weight of a paraffin wax (>C35) with a melting point of 58° C. as MSA, 5% by weight of benzil-α,α-dimethyl acetal (IGM resin BV) and 0%, 0.25% or 0.5% of 1-hydroxycyclohexyl phenyl ketone (C1) (IGM resin BV). The exposure was carried out in a CombiFIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The relief precursor was exposed from the back for 14 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm2 The intensity of the exposure is continued through the mask layer for 8 minutes. Flowline Washer FV (Flint Group) Flexosol-i (DuPont) was used as the washout medium and the precursor was developed at a rate of 150 mm / min. Drying took place at 60° C. within 120 minutes. Re-exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HOSLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was 2 minutes.

[0173] Printing conditions:

[0174] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on an LD-PE film (Delo) that was corona pretreated on one side and had a width of 400 mm and a thickness of 55 μm using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The anilox roller used was set with a screen resolution of 420 lines / cm and a 3.5 cm 3 / m 2 The printing speed is 200m / min.

[0175] Table 8:

[0176]

[0177] Very large inflow =--

[0178] Large inflow = -

[0179] Medium inflow = 0

[0180] Small inflow = +

[0181] No inflow =++

[0182] The influx was reduced by increasing the UVC photoinitiator content while keeping the UVA photoinitiator content the same. In the case of 0.5% UVC photoinitiator (Example 7c), hardly any influx was observed (Table 8).

[0183] Example 8:

[0184] A SIS-based relief precursor (thickness 1.70 mm) was produced on a polyester support with 1% by weight of paraffin wax (>C35) having a melting point of 58° C., 5% by weight of benzil-α,α-dimethyl acetal (IGM resin BV) and 0%, 0.25% or 0.5% of 1-hydroxycyclohexyl phenyl ketone (C1) (IGM resin BV). The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The relief precursor was exposed from the back for 40 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The intensity of the exposure is continued through the mask layer for 8 minutes. The precursor was developed in a Flowline Washer FV (Flint Group) using nylosolv A (Flint Group) as the wash medium at a rate of 230 mm / min. Drying took place at 60°C over 120 minutes. Further exposure then took place at room temperature, with UVA exposure (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was 4 minutes.

[0185] Printing conditions:

[0186] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on an LD-PE film (Delo) that was corona pretreated on one side and had a width of 400 mm and a thickness of 55 μm using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The anilox roller used was set with a screen resolution of 420 lines / cm and a 3.5 cm 3 / m 2 The printing speed is 200m / min.

[0187] Table 9:

[0188]

[0189] Very large inflow =--

[0190] Large inflow = -

[0191] Medium inflow = 0

[0192] Small inflow = +

[0193] No inflow =++

[0194] When compared to reference 8a, the inflow of the plates was drastically reduced by adding MSA and photoinitiator C1 (Examples 8b and 8c). A further increase in the UVC photoinitiator content from 0.5% (Example 8b) to 1% (Example 8c) did not lead to further improvements in inflow (Table 9).

[0195] Example 9:

[0196] An SBS-based relief precursor (thickness 1.70 mm) was produced on a polyester support with 1% by weight of paraffin wax (>C35) having a melting point of 58° C., 1% by weight of benzil-α,α-dimethyl acetal (IGM resin BV) and 0%, 0.5%, 1.0%, 1.5% or 2.0% of 1-(4-methylphenyl)-1-dodecanone (C3) (BASF). The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The relief precursor was exposed from the back for 40 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm 2 The strength of the film was exposed for 9 minutes by attaching a mask layer fixed by vacuum. After removing the mask layer, the Flowline Washer FV (Flint Group) Flexosol-i (DuPont) was used as the washout medium and the precursor was developed at a rate of 250 mm / min. Drying took place at 60° C. within 120 minutes. Re-exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 10 minutes and the UVC exposure time was 5 minutes.

[0197] Printing conditions:

[0198] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on an LD-PE film (Delo) that was corona pretreated on one side and had a width of 400 mm and a thickness of 55 μm using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The anilox roller used was set with a screen resolution of 420 lines / cm and a 3.5 cm 3 / m 2 The printing speed is 200m / min.

[0199] Table 10:

[0200]

[0201] Very large inflow =--

[0202] Large inflow = -

[0203] Medium inflow = 0

[0204] Small inflow = +

[0205] No inflow =++

[0206] In reference 9a, a significant influx of the plate was observed. By adding MSA and photoinitiator C3, the influx was drastically reduced (Examples 9b to 9e). From a 1.0% concentration of UVC photoinitiator C3 (Example 9c), virtually no influx was observed. The same applies to further increases in UVC photoinitiator concentration to 1.5% or 2.0% (Examples 9d and 9e) (Table 10).

[0207] Example 10:

[0208] SIS-based relief precursors (total thickness 1.14 mm) were produced on a polyester support 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-dimethylacetal (IGM resin BV) and 0% or 0.5% of 1-hydroxycyclohexyl phenyl ketone (C1) (IGM resin BV). The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 The relief precursor was exposed from the back for 10 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently in a The exposure was carried out in a Combi FIII exposure unit (Flint Group) at 40°C with the aid of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 The intensity of the exposure through the mask layer lasts for 15 minutes. The exposed precursor was washed out in a Digital Washer FIII (Flint Group) with the aid of nylosolv A at a rate of 200 mm / min. Drying took place at 60° C. within 120 minutes. Different re-exposures were performed in a Combi FIII exposure unit using only UVA (Philips TL 60W / 10-R, intensity 11 mW / cm 2 ) exposure, using only UVC (Philips TUV 75W HO G75 T8, intensity 13mW / cm 2 ) exposure, or simultaneous UVA and UVC exposure, in each case at 40°C. Simultaneous in this context means that both exposures (UVA and UVC) began at the same time. After storage for at least one week after development of the printing plates, contact angle measurements were performed on the printed surfaces thus formed. The reference used was a surface of pure MSA obtained by melting and subsequent cooling.

[0209] The contact angle is a measure of surface wetting. Uniform wetting of a surface by a liquid (printing ink) is a basic prerequisite for a successful printing process. If wetting is incomplete, it will be impossible to transfer the printing form completely to the print medium. Wetting is crucially determined by the difference between the surface tension of the printing ink and the surface energy of the printing plate. If there is a significant difference between the surface tension of the liquid and the surface energy of the printing plate, a drop of liquid on the surface shows a larger contact angle. If the difference is small, the surface is uniformly wetted by the liquid, resulting in a small contact angle. MSA produces a hydrophobic surface. For example, in the case of polar liquids such as water, a large contact angle is expected.

[0210] Table 11 shows the contact angles of water drops on printing plates with and without MSA on the surface of the printing plates. The presence of MSA was controlled by re-exposure. Pure MSA was used as a reference.

[0211] Table 11:

[0212]

[0213] The presence of MSA on the surface has an impact 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 droplet is much greater than if MSA is not present on the surface. If MSA is present on the surface of the plate (Examples 10b, 10d and 10f), the contact angle of the water droplet approaches the contact angle of pure MSA (reference 10a). If MSA is not present, the photoinitiator concentration has a specific influence on the contact angle. With 1% UVC PI (Example 10e), a smaller contact angle is obtained than without UVC PI (Example 10c). The presence of MSA can therefore lead to wetting problems when printing with water-based inks. The migration of MSA can be controlled by re-exposure.

[0214] Example 11:

[0215] A SBS-based relief precursor (total thickness 1.14 mm) was produced on a polyester support 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-dimethylacetal (IGM resin BV). The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 The relief precursor was exposed from the back for 18 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently in a The exposure was carried out in a Combi FIII exposure unit (Flint Group) at 40°C with the aid of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 The intensity of the exposure through the mask layer lasts for 15 minutes. The exposed precursor was washed out in a Digital Washer FIII (Flint Group) with the aid of nylosolv A at a rate of 220 mm / min. Drying took place at 60° C. within 120 minutes. The printed plate was then The samples were then exposed to UVA light (Philips TL 60W / 10-R, intensity 11 mW / cm 2 ) for 10 min and then exposed to UVC light (Philips TUV 75W HO G75 T8, intensity 13 mW / cm 2 ) for 5 minutes. Both exposures (UVA and UVC) were initiated simultaneously and carried out at 40°C. After the printing plates had been developed and stored for at least one week, contact angle measurements were performed on the printed surfaces thus formed. The reference used was a surface of pure MSA obtained by melting and subsequent cooling.

[0216] Table 12:

[0217]

[0218] If MSA is present on the surface of the printing plate (Example 11b), the contact angle is close to that on pure MSA (reference 11a). In the absence of MSA on the surface of the plate (Example 11c), a much smaller contact angle is obtained, even if the other processing conditions are the same.

[0219] Example 12:

[0220] An SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support containing 1% by weight of a paraffin wax (>C35) with a melting point of 58° C. as MSA and 2% by weight of benzil-α,α-dimethyl acetal (IGM resin BV). The plates contained no MSA or 1% by weight of a paraffin wax (>C35) with a melting point of 58° C. or 0.5% by weight of polysiloxane polyester acrylate (PPA) as MSA. The exposure was carried out in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 26 mW / cm 2The relief precursor was exposed from the back for 20 seconds at an intensity of 100 nm. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Combi FIII exposure unit (Flint Group) with the aid of a fluorescent tube (Philips TL 60W / 10-R) at 26 mW / cm 2 The intensity of the exposure through the mask layer lasts for 10 minutes. The precursor was developed in a Flowline Washer FV (Flint Group) with the aid of nylosolv A (Flint Group) at a rate of 255 mm / min. Drying took place at 60° C. over 120 minutes. Further exposure then took place at room temperature, with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm 2 ) were started simultaneously and performed in parallel. The UVA exposure time was 10 minutes and the UVC exposure time was 6 minutes.

[0221] Printing conditions:

[0222] For printing with Flexocure Ancora Process Cyan UV curing ink (Flint Group), an MO4 printing press (Nilpeter) with an FA4 flexographic printing unit was used. The printing media used were PE-based self-adhesive label stock (Raflatac) or paper-based self-adhesive label stock with a thickness of 120 μm (Raflacoat, UPM) that was corona-treated on one side. The printing plates were fixed using Tesa blue foam tape (Tesa) of medium hardness. The anilox roller used was set with a screen resolution of 500 lines / cm and a 2.5 cm 3 / m 2 The printing speed was 100 m / min. The inflow was evaluated after approximately 500 linear meters.

[0223] result:

[0224] Table 13: Inflow of panels after printing on PE film and paper. Re-exposure used: Intensity UVA 7200 mJ / cm 2 ; UVC = 3960mJ / cm 2 The ratio of UVA / UVC re-exposure intensity = 1.8.

[0225] Table 13:

[0226]

[0227] Table 13 shows the effect of MSA on the flow of the board when printed with UV-curable inks. In the absence of MSA, significant flow was observed. By adding paraffin wax as the MSA, the flow of lumps was drastically reduced. When polysiloxane polyester acrylate was used as the MSA, further improvement in flow was observed.

Claims

1. A photopolymerizable relief precursor comprising: (A) a dimensionally stable carrier, (B) a photopolymerizable, relief-forming layer comprising at least a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a surface-active additive capable of migration, a photoinitiator activatable with UVA light, and a photoinitiator activatable with UVC light, Characterized in that the said surfactant additive capable of migration is paraffin, or Characterized in that the said surfactant additive capable of migration is polysiloxane polyester acrylate; and / or The invention is characterized in that the photoinitiator activatable by UVA light is selected from the group consisting of diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, benzil dimethyl ketal and benzil diethyl ketal, and the photoinitiator activatable by UVC light is selected from the group consisting of 2-[2-oxo-2-phenylacetoxy-ethoxy] ethyl oxyphenylacetate, 2-[2-hydroxyethoxy] ethyl oxyphenylacetate, methylbenzoylformate, p-tolyl undecyl ketone, 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenylpropane-1-one and mixtures thereof.

2. The photopolymerizable relief precursor according to claim 1, characterized in that The surface-active additive capable of migration is a paraffin wax having a chain length of greater than 15 C atoms.

3. The photopolymerizable relief precursor according to claim 1, wherein The photopolymerized relief-forming layer comprises the migratable surface-active additive in an amount of 0.1% to 10% by weight based on the weight of the photopolymerized relief-forming layer.

4. Photopolymerizable relief precursor according to one of claims 1 to 3, characterized in that The photopolymerized relief-forming layer comprises the photoinitiator activatable with UVA light in an amount of 0.5 to 20% by weight, based on the total weight of the photopolymerized relief-forming layer.

5. Photopolymerizable relief precursor according to one of claims 1 to 4, characterized in that The photopolymerized relief-forming layer comprises the photoinitiator activatable with UVC light in a concentration of 0.1% to 20% by weight, based on the total weight of the photopolymerized relief-forming layer.

6. Photopolymerizable relief precursor according to one of claims 1 to 5, characterized in that The mass ratio of the photoinitiator activatable with UVA light to the photoinitiator activatable with UVC light is from 0.1 to 50.

7. A method for producing a relief structure comprising the steps of: (i) providing a photopolymerizable relief precursor according to any one of claims 1 to 6, (ii) applying a mask or producing a structured masking layer over the photopolymerizable relief-forming layer, (iii) optionally exposing the back side to electromagnetic radiation through the carrier layer, (iv-a) exposing the photopolymerized relief-forming layer to electromagnetic radiation through the mask or mask layer, (v) removing the mask or mask layer, any further layers that may be present and the non-photopolymerized areas of the relief-forming layer that were not exposed in step (iv-a), thereby producing a relief, (vi) optional drying of the relief, (vii) re-exposing the relief from the side facing away from the support layer to UVA light in the wavelength range from 315 nm to 380 nm and / or UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is re-crosslinked and the permeability of the relief to the migratable surface-active additive is adjusted for adjusting the surface properties of the relief, (viii) optionally further processing steps.

8. A method for producing a relief structure comprising the steps of: (i) providing a photopolymerizable relief precursor according to any one of claims 1 to 6, (iii) optionally exposing the back side to electromagnetic radiation through the carrier layer, (iv-b) imagewise exposing the photopolymerized relief-forming layer to electromagnetic radiation, (v) removing any further layers that may be present and the non-photopolymerized areas of the relief-forming layer that were not exposed in step (iv-b), thereby producing a relief, (vi) optional drying of the relief, (vii) re-exposing the relief from the side facing away from the support layer to UVA light in the wavelength range from 315 nm to 380 nm and / or UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is re-crosslinked and the permeability of the relief to the migratable surface-active additive is adjusted for adjusting the surface properties of the relief, (viii) optionally further processing steps.

9. The method according to claim 7 or claim 8, characterized in that In step (vii), the re-exposure is to UVA light and UVC light, whereby the re-exposure to UVA light and UVC light occurs simultaneously or alternately.

10. The method according to claim 7 or claim 8, characterized in that The re-exposure conditions are adjusted according to the type of printing ink in order to adjust the surface properties of the relief with respect to the printing ink.

11. The method according to claim 10, characterized in that By choice of the 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.

12. Method according to one of claims 7 to 11, characterized in that The method is used to produce an optimized relief structure, the method being carried out multiple times through steps (i) to (viii), wherein in step (vii), the re-exposure to UVA light and / or UVC light is varied in terms of the dosage and / or time sequence of the UVA and UVC re-exposure steps in order to optimize the surface properties of the relief.

13. Method according to one of claims 7 to 12, characterized in that The migration of the at least one migratable surfactant additive is controlled by selecting the exposure parameters of the re-exposure step.

14. Method according to one of claims 7 to 13, characterized in that There is a range from 100mJ / cm 2 Up to 30,000mJ / cm 2 Re-exposure to doses of UVA light.

15. Method according to one of claims 7 to 14, characterized in that There is a range from 100mJ / cm 2 Up to 20,000mJ / cm 2 Re-exposure to a dose of UVC light.

16. Method according to one of claims 7 to 15, characterized in that The dose ratio of UVA light to UVC light is greater than 0.

2.

17. Method according to one of claims 7 to 10, characterized in that Exposure to UVC light seals the surface of the layer due to the lower penetration depth, and exposure to UVA light ensures stronger cross-linking throughout the layer.

18. Relief structure obtainable using a method according to one of claims 7 to 17.

19. Use of the relief structure according to claim 18 as a pad, a flexible plate, a relief printing plate, a gravure printing plate, a microfluidic component, a microreactor, an electrophoretic cell or an optical component.

20. Use of the relief structure according to claim 18 as a photonic crystal.

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