Photopolymerizable relief precursors with tunable surface properties

Abstract

The present application relates to a photopolymerizable relief precursor having tunable surface properties. Specifically, the present invention relates to a photopolymerizable relief precursor comprising (A) a dimensionally stable support, (B) a photopolymerizable relief forming layer, the photopolymerizable relief-forming layer comprises at least a crosslinkable elastomeric adhesive, an ethylenically unsaturated monomer, a transferable surface-active additive, a photoinitiator that can be photoactivated with UVA and a photoinitiator that can be photoactivated with UVC. The invention also relates to a method for producing a relief structure.

Description

[0001] This application is a divisional application of the application with the application date of 14 December 2020, the application number 202080086466.1 and the invention title “Photopolymerized relief precursor with adjustable surface properties”.

[0002] The present invention relates to a photopolymerized relief precursor with surface properties that can be adjusted by exposure conditions, to a method for producing a relief structure from the relief precursor, to the relief structure itself and to its use.

[0003] Printing with solvent-based inks requires the printing plate to have an ink-repellent surface in order to prevent the ink from flowing into the interstitial spaces between the screen dots. This is usually achieved by the presence of a mobile surface-active additive (MSA) in the relief layer, which reduces the surface tension of the printing surface. However, the presence of such an additive can be problematic when printing with UV-cured inks or water-based inks, 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-cured inks or water-based inks. Examples of such printing plates are indicated in EP1014194A1, but such printing plates are only suitable for a specific type of solvent-based ink.

[0004] It is an object of the present invention to provide a printing plate that 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 for a printing plate that is printed with solvent-based inks are different from the requirements for a printing plate that is printed with UV-cured inks or water-based inks.

[0005] The object is achieved with a photopolymerized relief precursor, which comprises:

[0006] (A) a dimensionally stable carrier,

[0007] (B) a photopolymerizable relief-forming layer, which at least contains a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a mobile surface-active additive, a photoinitiator activatable with UVA light and a photoinitiator activatable with UVC light.

[0008] The relief precursor according to the present application makes it possible to control the 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 make this surface hydrophobic. Exposure to UVA light to a greater penetration depth ensures greater crosslinking in the entire relief layer and stabilizes the relief as a whole. Exposure to UVC light results in a smaller penetration depth into the photoactive layer and ensures that there is still a large amount of re-crosslinking of monomers and polymers. As a result, the migration of MSA to the surface of the relief is reduced or prevented, which leads to a more hydrophilic surface. This in turn facilitates wetting of the printing area with a hydrophilic printing ink. UVC exposure can also cause oxidation of the formulation ingredients, which leads to the formation of polar and hydrophilic groups.

[0009] The relief precursor for use as a printing plate according to the present application allows the following advantages to be achieved, among others:

[0010] The surface properties can be adjusted in such a way that the flow of solvent-based ink into the interstitial spaces between the screen dots during printing is prevented or reduced. This in turn allows longer printing times before the plate has to be cleaned.

[0011] The tackiness of the surface and thus the tendency for dust and dirt to accumulate on the surface can be reduced by adjusting the surface properties.

[0012] The same printing plate can be used for printing with different types of printing ink, since the surface properties can be adjusted in such a way that the printing plate is suitable for printing with solvent-based inks, water-based inks or UV-curing inks by selecting the re-exposure conditions.

[0013] The dimensionally stable carrier material, which can optionally present an additional layer, can be used as the dimensionally stable carrier (A). Examples of suitable dimensionally stable carriers are plates, films and conical and cylindrical sleeves made of metal, such as steel, aluminium, copper or nickel, or made of plastic, such as polyethylene terephthalate, polybutylene terephthalate, polyamide or polycarbonate, or made of woven or non-woven fabric, such as glass fibre woven fabric, or made of composite materials of glass fibre 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 aluminium sheets. These carrier films have a thickness of generally 50 to 1000 μιη, preferably 75 to 400 μιη, for example about 250 μιη. If a plastic film is used, its thickness is in the range from 100 to 200 μιη, preferably 125 to 175 μιη. If steel is used as the carrier material, steel sheets having 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 on the side of the carrier film facing the substrate layer with a thin adhesion-promoting layer, for example a layer having a thickness of 0.05 to 5 μιη. The adhesion layer can consist, for example, of a mixture of polycarbonate, phenoxy resin and polyfunctional isocyanate.

[0014] These carrier films or carrier sheets can already be equipped with or provided with a thin adhesion-promoting layer (AH). For the adhesion layer, it is possible to use, for example, polyurethane adhesion varnishes based on polyisocyanates (for example according to DE 30 45 516) - crosslinking polyether varnishes or polyester varnishes, the layer thickness being between 0.5 μιη and 50 μιη, in particular between 2 μιη and 30 μιη.

[0015] On the side of the adhesion layer facing away from the carrier layer, a further adhesion-promoting intermediate layer (AH) can be present. These have a layer thickness of between 0.1 μιη and 50 μιη, in particular between 1 μιη and 10 μιη, and can be obtained, for example, from a diluted aqueous-alcoholic solution of partially (for example up to 80 mol %) hydrolysed polyvinyl ester, phenyl glyceryl ether monacrylate and glyoxal, with drying and baking.

[0016] The adhesion-promoting layer or intermediate layer is intended to increase the adhesion between the individual layers and to stabilise the layer structure. This requires the selection of a material which can establish an interaction with both layers. Preferred examples of this material are surfactants, amphiphilic molecules having hydrophobic and hydrophilic regions and block copolymers, and oligomers containing blocks which are compatible with the polymers in both layers. The adhesion between the dimensionally stable carrier (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.

[0017] The relief precursor comprises at least one photopolymerizable relief-forming layer (B). The photopolymerizable relief-forming layer can be applied directly on the support. However, further layers can also be present between the support and the relief-forming layer, such as an adhesive layer or an elastic or compressible underlayer.

[0018] The relief-forming layer (B) can also consist of more than one layer, in which case it usually comprises 2 to 30 layers, preferably 2 to 5 layers, more preferably 2 to 3 layers and very preferably 2 layers. The layers can contain the same components or different components and in the same proportions or in 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 on these fixed, crosslinked and / or reacted layers is the relief-forming layer, which can also be fixed or crosslinked or can also react.

[0019] The skilled person is aware of the elastomeric binders for the relief-forming layer for the production of flexographic printing elements. Examples include styrene-diene block copolymers, natural rubber, polybutadiene, polyisoprene, butadiene-styrene rubber, butyl 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.

[0020] Preferably, the elastomer is a thermoplastic elastomeric block copolymer of alkenyl arenes and 1,3-dienes. The block copolymers can be linear, branched or radial block copolymers. Usually they are A-B-A triblock copolymers, but they can also be A-B diblock polymers or polymers with more than one alternating elastomeric and thermoplastic block, for example A-B-A-B-A. Mixtures of two or more different block copolymers can also be used. Commercially available triblock copolymers usually contain a proportion of diblock copolymers. The diene units can be connected 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 available, for example, under the names are commercially available. Thermoplastic elastomeric block copolymers with terminal styrene blocks and statistical styrene-butadiene middle blocks can also be used. The block copolymers can also be fully or partially hydrogenated, such as in SEBS rubber. Preferred elastomeric binders are triblock copolymers of the A-B-A type or radial block copolymers of the (AB)n type, in which A is styrene and B is diene; and statistical and random copolymers of styrene and diene.

[0021] In a preferred embodiment of the application, the thermoplastic elastomer adhesive comprises at least one styrene-isoprene block copolymer, in particular a styrene-isoprene-styrene block copolymer, wherein the polymer can also contain a proportion of di-block styrene-isoprene copolymers. Preferred styrene-isoprene type adhesives generally contain 10 to 30 % by weight, preferably 12 to 28 % by weight and more preferably 13 to 25 % by weight of styrene. In a further embodiment, the adhesive is a styrene-butadiene-styrene (SBS) block copolymer. Preferred SBS polymers generally contain 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 an average molecular weight Mw (weight average) of 100,000 to 300,000 g / mol. Of course, mixtures of different styrene-isoprene block copolymers or styrene-butadiene block copolymers can also be used.

[0022] In a second embodiment of the application, radial isoprene-styrene block copolymers can be used preferentially. The isoprene units and / or butadiene units in the polyisoprene blocks can be 1,4 linked, meaning that the remaining double bond is arranged in the chain, or 3,4 linked, meaning that the remaining double bond is arranged in a pendant manner. Block copolymers having essentially 1,4 bonds and adhesives having a proportion of 3,4 bonds can be used. The vinyl side groups in adhesives having 3,4-linked units can preferably be able to react in the crosslinking process of the photopolymerized layer and thus produce a plate having high crosslinking. For example, block copolymers having a vinyl group content of 20 to 70 % can be used.

[0023] In a preferred embodiment of the present application, a radial styrene-isoprene copolymer having a vinyl group content of less than 10% can be used. In a second preferred embodiment of the present application, 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 20% to 70%, and preferably 25% to 45%. The other one can have a low vinyl group content, for example a vinyl group content of less than 10%. It is also preferred that a mixture of two styrene-isoprene copolymers can be used, wherein one has a high di-block fraction of more than 40% by weight, while the second one has a low di-block fraction of less than 30% by weight. In addition to the stated thermoplastic elastomeric block copolymers, in particular styrene-isoprene block copolymers, the photopolymerizable layer can also comprise a further elastomeric binder different from the block copolymers. Such a further binder, also referred to as secondary binder, enables the properties of the photopolymerizable layer to be varied. Vinyltoluene-alpha-methylstyrene copolymers are examples of secondary binders. Generally, the amount of such a secondary binder should not exceed 25% by weight based on the total amount of all binders used. Preferably, the amount of such a secondary binder does not exceed 15% by weight, more preferably does not exceed 10% by weight. The total amount of binders is generally 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.

[0024] In the case of a relief precursor which can be water-developed, water-soluble, swellable, dispersible or emulsifiable polymers are used. In addition to completely or partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polystyrene sulfonate, polyurethane, polyamide such as those described in EP 0085472 or in DE 1522444 and any combination thereof can be used. Examples of such polymers can be found in EP 0079514, EP 0224164 or EP 0059988. These polymers can be linear, branched, star-shaped or dendritic and exist as homopolymers, statistical copolymers, block copolymers or alternating copolymers. Generally, the stated polymers are provided with functional groups which can increase the solubility and / or participate in crosslinking reactions. These groups include, for example, carboxyl groups, SO3 groups, OH groups, thiol groups, olefinically unsaturated (meth)acrylate groups and epoxy groups and any combination thereof.

[0025] In the case of the relief-forming layer (B), the total amount of binders 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.

[0026] The relief-forming layer (B) can comprise further ingredients selected from the group consisting of plasticizers, solvents, other binders, colorants, stabilizers, regulators, UV absorbers, dispersing aids, crosslinking agents, viscosity regulators, surface-active substances and any combination thereof. These additives, aids and adjuvants are contained in the radiation-sensitive mixture in a total concentration in the range of 0.001 to 60% by weight, preferably in the range of 0.01 to 50% by weight, more preferably in the range of 0.1 to 50% by weight and very preferably in the range of 1 to 50% by weight, based on the total formulation. The individual additives are contained in a concentration of from 0.001 to 40% by weight, preferably in the range of 0.01 to 40% by weight, more preferably in the range of 0.1 to 40% by weight and very preferably in the range of 0.1 to 35% by weight, based on the total formulation.

[0027] The photopolymerizable relief-forming layer (B) also comprises at least one ethylenically unsaturated monomer which is compatible with the one or more binders in a known manner. 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. They are therefore referred to as monomers hereinafter. Monomers which have been found to be particularly advantageous are esters or amides of acrylic or methacrylic acid with monofunctional or polyfunctional alcohols, amines, aminoalcohols or hydroxyethers and esters, esters of fumaric acid or maleic acid, vinyl ethers, vinyl esters and allyl compounds.

[0028] Generally, these monomers are not gaseous compounds at room temperature. Preferably, the ethylenically unsaturated monomer comprises at least 2 ethylenically unsaturated groups, more preferably 2 to 10 ethylenically unsaturated groups and very preferably 2 to 6 ethylenically unsaturated groups. Compounds with 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 which is 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.

[0029] Derivatives of acryl or methacryl acid, such as their esters with monohydric or polyhydric alcohols, for example acrylates or methacrylates 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 polyhydric alcohols having 2 to 20 carbon atoms, for example 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, 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, m-methyl poly(ethylene oxide)-based (meth)acrylate, N,N-diethylaminoethyl acrylate, the reaction product from 1 mol of glycerol, 1 mol of epichlorohydrin and 3 mol of acrylic acid; and glycidyl methacrylate and bisphenol A diglycidyl ether acrylate.

[0030] Also suitable are derivatives of acrylamide and methacrylamide, such as ethers of their N-methylol derivatives with monohydric and polyhydric alcohols, for example ethylene glycol, glycerol, 1,1,1 -trimethylolpropane, oligomers or polymeric oxirane derivatives. These are particularly suitable if a polyamide or a polyvinyl alcohol is used as binder.

[0031] Also suitable are those which are referred to as epoxy (meth)acrylates and urethane (meth)acrylates, such as those which can be obtained 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 which contain hydroxyl groups. Further olefinically unsaturated compounds which can be used include esters of acrylic or methacrylic acid, in particular those having a low vapour pressure and those which are modified by compatibilisers, for example those which are modified with hydroxyl groups, amido groups, sulphonated ester groups or sulphonamide groups. Mixtures of the above-mentioned copolymerisable olefinically unsaturated organic compounds can also be used.

[0032] 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.

[0033] In one embodiment, the ethylenically unsaturated monomer is 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.

[0034] The photopolymerizable relief-forming layer further comprises a mobile surface-active additive.

[0035] Preferred mobile surface-active additives are selected from the group consisting of ionic or non-ionic 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 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-22-161 B, KF-8010, Silmer OH ACR C50, Silmer OH ACR Di-400, Silmer ACR Di-10, Silmer OH ACR D4, AFCONA-3835 and Sartomer CN9800.

[0036] In a preferred embodiment, the migratable surface active additive is a paraffin wax. Branched paraffin waxes 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.

[0037] The photopolymerizable relief-forming layer further comprises a photo initiator activatable with UVA light and a photo initiator activatable with UVC light.

[0038] Preferred photo initiators activatable with UVA light are selected from the group consisting of benzil ketals, acylphosphine oxides, bisacylphosphine oxides, aminophenyl ketones, phenyl oximes esters and mixtures thereof.

[0039] Preferred photo initiators activatable with UVC light are selected from the group consisting of hydroxyphenyl ketones, benzoyl formate esters, benzophenone, arylalkyl ketones, arylbenzyl ketones and mixtures thereof.

[0040] In a particularly preferred embodiment, the photo initiator 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 photo initiator activatable with UVC light is selected from the group consisting of oxyphenyl acetic acid 2-[2-oxo-2-phenylacetyloxy-ethoxy]ethyl ester, oxyphenyl acetic acid 2-[2-hydroxyethoxy]ethyl ester, methyl benzoyl formate ester, p-tolyl undecyl ketone, 1 hydroxy cyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenylpropan-1-one and mixtures thereof.

[0041] The migratable surface active additive is typically included in the photopolymerizable 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 photopolymerizable relief-forming layer.

[0042] The photo initiator activatable with UVA light is typically included in the photopolymerizable 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 photopolymerizable relief-forming layer.

[0043] The photo-initiator activatable with UVC light is generally included in the photopolymerized relief-forming layer at 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.

[0044] Generally, the mass ratio of the photo-initiator activatable with UVA light to the photo-initiator activatable with UVC light is 0.1 to 50, preferably 0.5 to 40, more preferably 0.5 to 30, and very preferably 0.5 to 15.

[0045] Generally, the ratio of the photo-initiator activatable with UVA light to the amount of the migratable surface-active additive is 0.01 to 10, preferably 0.1 to 5, and more preferably 0.1 to 3.

[0046] The photopolymerized relief precursor according to the present application can present one or more than one additional layer 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, such as a structure-imparting layer, a barrier layer, a cover layer, and a digitally reproducible mask layer, arranged above the relief-forming layer, and combinations of two or more of these layers.

[0047] For example, the photopolymerized relief precursor can present an intermediate layer, preferably an adhesive layer and / or a compressible layer, between the support layer and the photopolymerized relief-forming layer.

[0048] The photopolymerized relief precursor can present on the side of the photopolymerized relief-forming layer facing away from the support layer an additional layer selected from the group consisting of a mask layer, a barrier layer, a cover layer, and combinations of two or more of these layers.

[0049] In a preferred embodiment, the photopolymerized relief precursor comprises:

[0050] (A) a dimensionally stable support;

[0051] (AH) optionally an adhesion-promoting layer;

[0052] (B) a photopolymerized relief-forming layer comprising at least a cross-linkable elastomeric binder, an ethylenically unsaturated monomer, a migratable surface-active additive, a photo-initiator activatable with UVA light, and a photo-initiator activatable with UVC light;

[0053] (C) a laser-ablatable mask layer comprising at least a non-radically cross-linkable elastomeric polymer, a UVA light-absorbing material, and an IR light-absorbing material; and optionally

[0054] (D) a cover layer that can be peeled off.

[0055] The relief precursor according to the application preferably comprises a laser-ablatable mask layer (C) which is arranged above the relief-forming layer (B) and which can also be removed using solvents or by heating and adsorption / absorption. This layer is heated and volatilized by means of high-energy electromagnetic radiation by selective irradiation, thereby producing a mask with an imagewise structure which is used to transfer the structure to the relief precursor. For this purpose, it must be non-permeable in the UV range and must absorb radiation in the VIS-IR range, resulting in the layer being heated and ablated.

[0056] The optical density of the mask layer in the UV range from 330 nm to 420 nm is in the range from 1 to 5, more preferably in the range from 1.5 to 4 and very preferably in the range from 2 to 4. The optical density is determined by measuring with an X-rite 361 TX densitometer in the "Density" device with UV filter.

[0057] The layer thickness M of the laser-ablatable mask layer (C) is generally from 0.1 μm to 5 μm. If the layer thickness is below 0.1 μm, it is very difficult to achieve sufficient optical density. If the layer thickness is greater than 5 μm, the laser sensitivity of the element is too low, so that long laser times are required for imaging. The layer thickness is preferably from 0.3 μm to 4 μm, in particular from 1 μm to 3 μm. The laser sensitivity of the mask layer (measured as the energy required in order to ablate 1 cm 2 of the layer) should be between 0.1 J / cm 2 and 10 J / cm 2 , preferably between 0.3 J / cm 2 and 5 J / cm 2 and more preferably between 0.5 J / cm 2 and 5 J / cm 2 .

[0058] The mask layer (C) comprises at least one non-radically crosslinkable elastomeric polymer which is able to homogeneously distribute the components which absorb electromagnetic radiation and ablate as efficiently as possible when heated. The elastomeric polymer can be a linear, branched, star-shaped, comb-shaped or dendritic homo- or copolymer. The copolymer can be present as a statistical copolymer and / or as a block copolymer. The elastomeric polymer can also be a mixture of different polymers which 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.

[0059] Examples of very suitable non-radically 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) copolymer (or poly(vinyl butyral vinyl alcohol vinyl acetal) copolymer). Other flexible elastic materials can of course also be used as adhesive, such as for example partially hydrolysed polyvinyl acetate. Preferred adhesives for the mask layer (C) are flexible elastic polyamides, polyvinyl alcohol, partially hydrolysed polyvinyl acetate or partially hydrolysed polyvinyl acetal.

[0060] The mask layer (C) can be permeable or impermeable to oxygen.

[0061] In general, the relief-forming layer (B) and the ablatable mask layer (C) are soluble in ordinary, commercially available rinsing media, which generally consist of solvent mixtures or aqueous solutions. These rinsing media consist of one or more non-polar hydrocarbon solvents as the main component, with the secondary component in the form of a moderately polar alcohol, such as benzyl alcohol, n-pentanol, cyclohexanol, ethylhexanol or heptanol. Aqueous solutions generally contain surfactants and / or flocculants and generally have a pH > 7. The relief-forming layer (C) can be processed in these rinsing media at the usual times.

[0062] In addition, it is also possible to thermally develop or remove the relief-forming layer (B) and the ablatable mask layer (C) (see for example EP 1239 329 or EP 1 170 121). In this case, after the imagewise exposure, the relief structure is heated to the softening temperature or the melting temperature. This causes the unexposed and uncrosslinked regions of the relief structure to become partly liquid and viscous and they are then removed continuously by blotting up (absorbing) with a non-woven or woven fabric.

[0063] In a further embodiment, there is an additional layer (E) between layer (B) and layer (C) in the relief precursor according to the application, which additional 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 to 5 pm. In addition to adjuvants, the layer mainly comprises one or more elastic polymers having a low oxygen permeability, the oxygen permeability of the elastic polymer being of the order of magnitude of less than or equal to 1.5*105cm 3 *pm / (m 2 *d*bar). The polymers in layer (E) are preferably likewise non-radically crosslinkable.

[0064] Examples of suitable elastic polymers which can be heat-developed and / or soluble in organic solvents and have a sufficient barrier effect against oxygen are partially hydrolyzed polyvinyl acetates having a degree of hydrolysis of from 30 mol% up to a maximum of 80 mol%, ethylene-vinyl acetate copolymers and ethylene-vinyl alcohol copolymers, and also ethylene-vinyl acetate-vinyl alcohol copolymers. Also highly suitable are cyclic acetals of polyvinyl alcohol, such as polyvinyl butyral, polyvinyl ethyl acetal, polyvinyl formal, polyvinyl propyl acetal, and also copolymers comprising two or more different vinyl acetal units selected from the group consisting of vinyl formal units, vinyl ethyl acetal units, vinyl propyl acetal units and vinyl butyl acetal units. The polyvinyl acetals are generally copolymers with vinyl alcohol units, since the reaction of polyvinyl alcohol with complete acetalization is incomplete for statistical and steric reasons. Thus, to be precise, poly(vinyl butyral) is a poly(vinyl butyral-vinyl alcohol). The residual OH content of the stated polyvinyl acetals is generally between 10% and 30% by weight. For example, vinyl ethyl acetal-vinyl butyl acetal-vinyl alcohol copolymers (poly(vinyl ethyl acetal-vinyl butyl acetal)) are very suitable.

[0065] It is also an object of the present application a method for producing a relief structure, having the following steps:

[0066] (i) providing a photopolymerizable relief precursor comprising at least one surface-active additive capable of migration,

[0067] (ii) applying a mask or generating a structured mask layer above the photopolymerizable relief-forming layer,

[0068] (iii) optionally exposing the backside to electromagnetic radiation through the carrier layer,

[0069] (iv-a) exposing the photopolymerizable relief-forming layer to electromagnetic radiation through the mask or mask layer, preferably electromagnetic radiation in the wavelength range from 315 nm to 380 nm,

[0070] (v) removing the mask or mask layer, any additional layers that can be present, and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv), thereby producing a relief,

[0071] (vi) optional drying of the relief,

[0072] (vii) re-exposing the relief from the side facing away from the carrier layer to UVA light in the wavelength range from 315 nm to 380 nm and / or to UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is recrosslinked and the permeability of the relief to the surface-active additive capable of migration is adjusted, for adjusting the surface properties of the relief, preferably for the use with specific printing inks,

[0073] (viii) optionally further processing steps.

[0074] It is a further object of the present application a method for producing a relief structure, having the following steps:

[0075] (i) providing a photopolymerizable relief precursor comprising at least one migratable surface-active additive,

[0076] (iii) optionally exposing the backside to electromagnetic radiation through the carrier layer,

[0077] (iv-b) imagewise exposing the photopolymerizable relief-forming layer to electromagnetic radiation, preferably electromagnetic radiation in the wavelength range from 315 nm to 380 nm,

[0078] (v) removing any further layers that can be present and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv), thereby producing a relief,

[0079] (vi) optional drying of the relief,

[0080] (vii) re-exposing the relief from the side facing away from the carrier layer to UVA light in the wavelength range from 315 nm to 380 nm and / or to UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is recrosslinked and the permeability of the relief for the migratable surface-active additive is adjusted for adjusting the surface properties of the relief, preferably for the use with specific printing inks,

[0081] (viii) optionally further processing steps.

[0082] In preferred embodiments, the re-exposure in step (vii) occurs in the case of UVA light and UVC light. The re-exposure to UVA light and UVC light can occur simultaneously (concurrently) or in rotation (alternately).

[0083] In the case of re-exposure to UVA light, this is typically carried out with a dose of UVA light of from 100 mJ / cm 2 to 30,000 mJ / cm 2 . UVA light of from 100 mJ / cm 2 to 20,000 mJ / cm 2 is preferred, UVA light of from 100 mJ / cm 2 to 7,000 mJ / cm 2 is more preferred, and UVA light of from 500 mJ / cm 2 to 7,000 mJ / cm 2 is very preferred.

[0084] In case of re-exposure to UVC light, this is typically carried out with a dose of UVC light from 100 mJ / cm 2 to 20,000 mJ / cm 2 . UVC light from 100 mJ / cm 2 to 20,000 mJ / cm 2 is preferred, UVC light from 100 mJ / cm 2 to 8,000 mJ / cm 2 is more preferred, and UVC light from 500 mJ / cm 2 to 8,000 mJ / cm 2 is very preferred.

[0085] The re-exposure to UVA light and UVC light can occur simultaneously, consecutively or alternatively, with a dose ratio (D UVA / D UVC ) of UVA light to UVC light typically greater than 0.2, preferably greater than 0.4, more preferably greater than 0.6 and very preferably greater than 0.8. While the exposure to UVC light is preferably the surface of the sealing layer due to the lower penetration depth, the exposure to UVA light ensures a stronger crosslinking of the entire layer, so that a mechanically stable relief is obtained.

[0086] In a first step (i), the relief precursor described previously is provided. It can optionally be cleaned, in which case all techniques familiar to the skilled person can be used, such as, for example, brushing, blowing off, wiping (with and without solvent), rinsing and any desired combination thereof.

[0087] The wavelength of the irradiated electromagnetic radiation is in the range from 200 nm to 2,000 nm, preferably in the UV range, more preferably in the range from 200 nm to 550 nm, very preferably in the range from 300 nm to 450 nm. In addition to broadband irradiation of electromagnetic waves, it can be advantageous to use a narrowband or monochromatic wavelength range of the kind that can be produced using corresponding filters, lasers or light-emitting diodes (LEDs). In these cases, the preferred wavelengths are in the range of 350 nm, 365 nm, 385 nm, 395 nm, 400 nm, 405 nm, 532 nm, 830 nm, 1064 nm, individually (and high and / or low by about 5-10 nm) or as a combination.

[0088] In the presence of the cover layer (D), it is removed. Preferably, the cover layer is a protective film and is peeled off.

[0089] In step (ii), the mask layer is imaged by removing the layer and / or by imaging the locally resolved change in the absorption properties 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 with the aid of a high-energy laser, wherein the laser beam is guided over the mask layer under computer control. In this case, mainly IR lasers having a wavelength in the range from 500 nm to 20,000 nm, preferably in the range from 800 nm to 10,000 nm, more preferably in the range from 1,000 nm to 2,000 nm, are used. Wavelengths of approximately 830 nm, 980 nm, 1064 nm and 10.6 μιη or combinations thereof are particularly preferred.

[0090] In optional step (iii), the relief precursor can be irradiated extensively with electromagnetic radiation from at least one side. This irradiation preferably takes place from the side of the relief precursor opposite the mask layer in order to achieve anchoring (back exposure) of the relief structure to be produced. This back exposure preferably takes place through a transparent dimensionally stable material as carrier material, such as, for example, a polymer film, and in particular a polyester film. In the case of a non-transparent carrier material, step (iii) is omitted.

[0091] In step (iv-a), the relief precursor according to the application is exposed to electromagnetic radiation which passes through layer (C) and also, optionally, layer (E) triggers a reaction in those regions of layer (B) which are located below the exposed regions of layer (C), which leads to crosslinking of the constituents present in the layer. As a result of this crosslinking, these regions are stable and cannot be removed in the later development step. The irradiation is generally extensive, but can alternatively be carried out in small regions (vertical spotting) with the aid of a positionally resolved projection of a directed laser beam or electromagnetic radiation. The electromagnetic radiation used for this exposure generally has a wavelength in the range from 200 nm to 2,000 nm, preferably in the range from 315 nm to 380 nm.

[0092] Here, the irradiation can take place continuously or in pulses or with continuous radiation in more than one short period. The intensity of the radiation here can vary within wide ranges, ensuring that a dose is used which is sufficient to crosslink layer (B) for the later development procedure. The intensity of the radiation is generally in the range from 10 mW / cm 2 to 1,000 mW / cm 2 . The dose of the radiation is generally in the range from 3 J / cm 2 to 100 J / cm 2 , preferably in the range from 6 J / cm 2 to 20 J / cm 2The exposure to the energy source can also be carried out in an inert atmosphere, such as for example in a noble gas, CO2and / or nitrogen or under a liquid which does not damage the multilayer element.

[0093] The direct imaging exposure can be achieved by selectively exposing the regions to be crosslinked. This can be achieved for example with one or more laser beams which are controlled accordingly, by using a screen (certain pixels of which emit radiation are activated on the screen), by using a mobile LED strip (through an LED array in which individual LEDs are intentionally turned on and off), by using an electronically controllable mask (in which the pixels which allow the radiation of the radiation source to pass become transparent), by using a projection system (in which the pixels are exposed to the radiation from the radiation source by the corresponding orientation of the mirror) or combinations thereof. Direct exposure by means of a controlled laser beam or a projection system with a mirror 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.

[0094] In step (v), the uncrosslinked regions of layer (C) and, if present, layer (E) and also of layer (B) are removed, thereby producing a relief. In step (v), the non-exposed, non- photopolymerized regions of the relief-forming layer can be removed by treatment with a rinsing medium or by thermal treatment.

[0095] The layers can be removed individually or in groups or all together and simultaneously. Preferably, all layers and the uncrosslinked regions of layer (B) are removed in a single step. Depending on the nature of the layers, this can be achieved by treatment with a solvent-based rinsing medium or a water-based rinsing medium, such as for example organic solvents, mixtures thereof, water, aqueous solutions or water-organic solvent mixtures, which are able to dissolve, emulsify and / or disperse the uncrosslinked regions in layer (B).

[0096] In another embodiment, the removal of the uncrosslinked regions of layer (C) and, if present, layer (E) and also of layer (B) in step (v) takes place by heat, in other words, by the introduction of heat and removal of 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, action of a hot gas (for example air), use of a hot roller or any desired combination thereof. In order to remove the (viscous) liquid regions, all techniques and processes familiar to the skilled person can be used, such as, for example, blowing, suction, wiping, spraying (with particles and / or droplets), peeling, rubbing, transfer to a development medium and any desired combination thereof. Preferably, the liquid material is absorbed (absorbed and / or adsorbed) by a development medium which is in continuous contact with the heated surface of the relief precursor. This procedure is repeated until the desired relief height is achieved. Development media which can be used are paper, woven and non-woven fabrics, and films, which are able to absorb the liquefied material and can consist of natural fibers and / or polymeric fibers. Preference is given to the use of non-woven fabrics or non-woven 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.

[0097] It is also an object of the present application a method for producing an optimized relief structure, wherein the method is carried out several times by steps (i) to (viii), wherein in step (vii) the re-exposure to UVA light and / or UVC light is varied in terms of dose and / or time sequence of the UVA and UVC re-exposure steps in order to optimize the surface properties of the relief.

[0098] It is also an object of the present application a relief structure obtainable according to the method described above and its use. The relief structure can be used as a pad printer, a flexographic plate, an intaglio plate, a microfluidic component, a microreactor, an electrophoresis cell, a photonic crystal or an optical component. In the case of a microfluidic component or a microreactor, it can be advantageous to make the surface properties hydrophobic for the use of aqueous or very polar fluids in order to reduce the interaction with the walls or to create a hydrophilic surface when using non-polar fluids. In the case of an electrophoresis cell, a photonic crystal or an optical component, it can be advantageous to make the surface hydrophobic or hydrophilic, respectively, in terms of contamination and cleaning.

[0099] In particular, the present application provides the following:

[0100] 1 ) a photopolymerizable relief precursor, comprising:

[0101] (A) a dimensionally stable support,

[0102] (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.

[0103] 2) The photopolymerizable relief precursor according to 1), characterized in that the surface-active additive capable of migration is selected from the group consisting of ionic or non-ionic surfactants; long-chain hydrocarbons; waxes, in particular paraffin wax; organosilicon compounds, in particular silicone oils, silanes and siloxanes; or mixtures thereof.

[0104] 3) The photopolymerizable relief precursor according to 1) or 2), characterized in that the surface-active additive capable of migration is paraffin wax.

[0105] 4) The photopolymerizable relief precursor according to 1) or 2), characterized in that the surface-active additive capable of migration is a polysiloxane polyester acrylate.

[0106] 5) The photopolymerizable relief precursor according to one of 1) to 4), characterized in that the photoinitiator activatable with UVA light is selected from the group consisting of benzil ketals, acylphosphine oxides, bisacylphosphine oxides, aminophenyl ketones, phenyl oxime esters and mixtures thereof.

[0107] 6) The photopolymerizable relief precursor according to one of 1) to 5), characterized in that the photoinitiator activatable with UVC light is selected from the group consisting of hydroxyphenyl ketones, benzoylformate esters, benzophenone, arylalkyl ketones, arylbenzyl ketones and mixtures thereof.

[0108] 7) The photopolymerizable relief precursor according to 5) or 6), characterized in that 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 oxyphenyl acetate, 2-[2-hydroxyethoxy]ethyl oxyphenyl acetate, methyl benzoylformate, p-tolyl undecyl ketone, 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenylpropan-1-one and mixtures thereof.

[0109] 8). The photopolymerizable relief precursor according to one of 1 ) to 7), characterized in that the photopolymerizable relief-forming layer comprises the migratable surface-active additive 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 photopolymerizable relief-forming layer.

[0110] 9). The photopolymerizable relief precursor according to one of 1 ) to 8), characterized in that the photopolymerizable relief-forming layer comprises the UVA light activatable photoinitiator 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 photopolymerizable relief-forming layer.

[0111] 10.) The photopolymerizable relief precursor according to one of 1 ) to 9), characterized in that the photopolymerizable relief-forming layer comprises the UVC light activatable photoinitiator 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 photopolymerizable relief-forming layer.

[0112] 11 ). The photopolymerizable relief precursor according to one of 1 ) to 10), characterized in that the mass ratio of the UVA light activatable photoinitiator to the UVC light activatable photoinitiator is 0.1 to 50, preferably 0.5 to 40, more preferably 0.5 to 30 and very preferably 0.5 to 15.

[0113] 12). A method for producing a relief structure, comprising the following steps:

[0114] (i) providing a photopolymerizable relief precursor comprising at least one migratable surface-active additive,

[0115] (ii) applying a mask or creating a structured mask layer above the photopolymerizable relief-forming layer,

[0116] (iii) optionally exposing the backside to electromagnetic radiation through the carrier layer,

[0117] (iv-a) exposing the photopolymerizable relief-forming layer to electromagnetic radiation through the mask or mask layer,

[0118] (v) removing the mask or mask layer, any additional layers that can be present and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv-a), thereby producing a relief,

[0119] (vi) optional drying of the relief,

[0120] (vii) re-exposing the relief from the side facing away from the carrier layer to UVA light in the wavelength range from 315 nm to 380 nm and / or to UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is recrosslinked and the permeability of the relief for the migratable surface-active additive is adjusted for adjusting the surface properties of the relief,

[0121] (viii) optionally further processing steps.

[0122] 13). Method for producing a relief structure, comprising the following steps:

[0123] (i) providing a photopolymerizable relief precursor comprising at least one migratable surface-active additive,

[0124] (iii) optionally exposing the backside to electromagnetic radiation through the carrier layer,

[0125] (iv-b) imagewise exposing the photopolymerizable relief-forming layer to electromagnetic radiation,

[0126] (v) removing any further layers that can be present and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv-b), thereby producing a relief,

[0127] (vi) optional drying of the relief,

[0128] (vii) re-exposing the relief from the side facing away from the carrier layer to UVA light in the wavelength range from 315 nm to 380 nm and / or to UVC light in the wavelength range from 200 nm to 280 nm, whereby the relief is recrosslinked and the permeability of the relief for the migratable surface-active additive is adjusted for adjusting the surface properties of the relief,

[0129] (viii) optionally further processing steps.

[0130] 14). Method according to 12) or 13), characterized in that in step (vii) the re-exposure is to UVA light and to UVC light, whereby the re-exposure to UVA light and to UVC light occurs simultaneously, consecutively or alternately.

[0131] 15). Method according to 12) or 13), characterized in that the re-exposure conditions are adjusted depending on the type of printing ink for adjusting the surface properties of the relief for the printing ink.

[0132] 16) The method according to 15), characterized in that the surface properties can be adjusted in such a way that the printing plate is suitable for printing using solvent-based inks, aqueous inks or UV-cured inks, by the choice of the re-exposure conditions.

[0133] 17) The method for producing an optimized relief structure according to one of 12) to 16), characterized in that the method is carried out several times by steps (i) to (viii), wherein in step (vii) the re-exposure to UVA light and / or UVC light varies in terms of the dose and / or the temporal sequence of the UVA and UVC re-exposure steps in order to optimize the surface properties of the relief.

[0134] 18) The method according to one of 12) to 17), characterized in that the migration of the at least one migratable surface-active additive is controlled by the choice of the exposure parameters of the re-exposure step.

[0135] 19) The method according to one of 12) to 18), characterized in that there is a dose re-exposure to UVA light of from 100 mJ / cm 2 to 30,000 mJ / cm 2 , preferably 100 mJ / cm 2 to 20,000 mJ / cm 2 , more preferably 100 mJ / cm 2 to 7,000 mJ / cm 2 and very preferably 500 mJ / cm 2 to 7,000 mJ / cm 2 .

[0136] 20) The method according to one of 12) to 19), characterized in that there is a dose re-exposure to UVC light of from 100 mJ / cm 2 to 20,000 mJ / cm 2 , preferably 100 mJ / cm 2 to 20,000 mJ / cm 2 , more preferably 100 mJ / cm 2 to 8,000 mJ / cm 2 and very preferably 500 mJ / cm 2 to 8,000 mJ / cm 2 .

[0137] 21 ) The method according to one of 12) to 20), characterized in that the dose ratio of UVA light to UVC light (DUVA / DUVC) is greater than 0.2, preferably greater than 0.4, more preferably greater than 0.6 and very preferably greater than 0.8.

[0138] 22) The method according to one of 12) to 15), characterized in that the surface exposed to the UVC light sealing layer is exposed to the UVA light due to the lower penetration depth and the exposure to UVA light ensures a stronger crosslinking in the whole layer.

[0139] 23) A relief structure obtainable using the method according to one of 12) to 22).

[0140] 24) Use of the relief structure according to 23) as a pad for pad printing, a flexo plate, a letterpress printing plate, a gravure plate, a microfluidic component, a microreactor, an electrophoresis cell, a photonic crystal or an optical component. BRIEF DESCRIPTION OF DRAWINGS

[0141] Figures 1 to 3 The development of the gloss in gloss units (GU) as a function of time in days is shown for different re-exposure times.

[0142] Figures 4 to 6 The integration of the IR band at 719 cm -1 and 729 cm -1 is shown after 7 days for a given number of re-exposure times.

[0143] The application is illustrated in more detail by the following examples. EXAMPLE

[0144] Method:

[0145] Evaluation of the inflow

[0146] To evaluate the inflow, the plate was evaluated by assessing the tonal value field from 10% to 50% after printing of about 1,000 m. A high inflow (a lot of ink in the interstitial space) was classified as a "-" class, a medium inflow as a "0" class and a little to no inflow (no ink in the interstitial space) as a "+" class.

[0147] Method for the gloss measurement

[0148] Gloss measurements were performed to provide evidence on the presence of mobile surface active additives (MSA) on the surface of the board. The gloss was measured at a grazing angle of 60° by means of a micro-TRI-gloss μ glossmeter (BYK - Gardner GmbH). Prior to the measurements, the glossmeter was calibrated by means of a comprehensive calibration standard. The result was the average of three measurements at each different point on the surface of the board. Removal of the MSA by washing the surface with solvent resulted in an increase of the gloss to 40-50 GU.

[0149] Figures 1 to 3 The development of the gloss in gloss units (GU) as a function of time in days is shown for different re-exposure times.

[0150] Method for IR measurements

[0151] FT-IR measurements were performed to provide evidence on the presence of MSA on the surface of the board. 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 board. The data were captured and analyzed by means of Opus software version 7.5 (Bruker). The background correction of the spectra was done automatically. The integration of the IR bands at 719 cm -1 and 729 cm -1 was used as a measure for the presence of MSA. For this purpose, they were normalized with respect to the integration of the IR band at 1730 cm -1 and then subtracted from the zero value (result without MSA). The signal attributable to MSA was determined by IR spectroscopy of the pure substance. After removal of the MSA by washing the surface with solvent, the signal attributable to MSA in the IR spectrum was no longer visible.

[0152] Figures 4 to 6 The integration of the IR bands at 719 cm -1 and 729 cm -1 is shown for a given number of re-exposures after 7 days.

[0153] Method for contact angle measurements

[0154] By means of contact angle measurements, the influence of MSA on the wetting of the surface with water was investigated. For this purpose, a drop of 10 μί of demineralized water was dropped on the surface of the printed board. By means of a Keyence VHX-500F optical microscope using a VH-Z20R lens and a VH-S30 tripod, the profile of the water drop was captured. The radius r and the height h of the liquid drop were measured from these captures by the associated software. The contact angle θ was calculated using the trigonometric method (Equation 1).

[0155]

[0156] Example 1

[0157] A SBS-based relief precursor (total thickness 1.14 mm) was produced on a polyester support with 1% by weight of paraffin (> C20) with a melting point of 50-57°C as MSA and 2% by weight of benzil-a,a-dimethyl acetal (IGM Resin B.V.) was produced. The relief precursor was exposed from the back side in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 for 25 seconds. After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently developed in a Digital Washer FIII (Flint Group) by means of nylosolv A at a rate of 220 mm / min. Drying occurred at 60°C within 120 minutes. Then IR and gloss measurements were performed on the thus formed printing surface at certain time intervals. The reference did not contain any MSA. 1A means re-exposure to UVA light for 1 min, 1C means re-exposure to UVC light for 1 min. 2 for 15 minutes. In a Digital Washer FIII (Flint Group) the exposed precursor was washed out by means of nylosolv A at a rate of 220 mm / min. Drying occurred at 60°C within 120 minutes. Then IR and gloss measurements were performed on the thus formed printing surface at certain time intervals. The reference did not contain any MSA. 1A means re-exposure to UVA light for 1 min, 1C means re-exposure to UVC light for 1 min. 2 for 15 minutes. In a Digital Washer FIII (Flint Group) the exposed precursor was washed out by means of nylosolv A at a rate of 220 mm / min. Drying occurred at 60°C within 120 minutes. Then IR and gloss measurements were performed on the thus formed printing surface at certain time intervals. The reference did not contain any MSA. 1A means re-exposure to UVA light for 1 min, 1C means re-exposure to UVC light for 1 min. 2 Different re-exposures were performed in a Combi FIII exposure unit, wherein no exposure was used, only UVA (Philips TL 60W / 10-R, intensity 11 mW / cm 2 ) exposure, only UVC (Philips TUV 75W HO G75 T8, intensity 13 mW / cm 2 ) exposure, using continuous and simultaneous UVA and UVC exposure, in each case at 40°C. In this case, simultaneous means that both exposures (with UVA and UVC) start at the same time. Then IR and gloss measurements were performed on the thus formed printing surface at certain time intervals. The reference did not contain any MSA. 1A means re-exposure to UVA light for 1 min, 1C means re-exposure to UVC light for 1 min.

[0158] Figure 1 、 Figure 2 and Figure 3 show the evolution of the gloss on the surface of the printing plate as a function of time under various re-exposure conditions. The gloss values decrease as the MSA diffuses onto the surface. When compared to Figure 4 、 Figure 5and Figure 6 Upon comparison, it can be seen that the decrease in gloss value is associated with an increase in the IR signal. Upon re-exposure to UVC 3 min Figure 1 ) no clear influence of the UVA re-exposure time on MSA migration can be discerned. Upon re-exposure to UVC 10 min Figure 2 ) the amount of MSA decreases drastically with increasing re-exposure time. The influence of re-exposure to UVC on MSA migration is felt strongest when combined with re-exposure to UVA 10 min. Upon exposure to UVA 10 min and re-exposure to UVC 10 min, much less MSA reaches the printed surface than upon re-exposure to UVA 10 min without exposure to UVC Figure 3 ). The properties of the printed surface can thus be controlled.

[0159] Table 1: IR integral and gloss on printed surface after 2 days as a function of re-exposure conditions

[0160]

[0161] Table 1 shows the IR integral and gloss on printed surface after 2 days as a function of re-exposure conditions. The larger the value of the IR integral, the more MSA is present on the surface of the plate. The IR integral is related to the inverse of the gloss. Low gloss is evidence of MSA presence on the surface. In the absence of MSA, MSA cannot be found by IR spectroscopy. Upon exposure to UVA 10 min and re-exposure to UVC 10 min, much less MSA reaches the printed surface than upon no re-exposure or re-exposure to UVA 10 min without exposure to UVC. The properties of the printed surface can thus be controlled.

[0162] Table 2: IR integral and gloss on printed surface after 7 days

[0163]

[0164] Table 2 shows the influence of UVA and UVC exposure on MSA presence on the surface of the plate. A duration of 7 days was chosen in order to verify that MSA does not actually reach the surface. Reference 1 shows the values generated in the absence of MSA. Less UVA light and UVC light is applied to the printed plate with MSA, more MSA is present on the surface after 7 days. Here the influence of UVC light is greater than the influence of UVA light. The values obtained for the combination of UVA and UVC re-exposure correspond to the values of the printed plate without MSA.

[0165] Example 2

[0166] a) A SIS-based relief precursor (thickness 1.14 mm) was produced on a polyester support having 1% by weight of paraffin (> C35) with a melting point of 58°C as MSA and 5% by weight of benzil-a,a-dimethyl acetal (IGM Resins B.V.) and 0.5% by weight of 1-hydroxycyclohexyl phenyl ketone (IGM Resins B.V.) as photoinitiator.

[0167] b) Second relief precursor, but without 1-hydroxycyclohexyl phenyl ketone, produced as in a).

[0168] In Both plate types were exposed from the back in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 for 15 seconds (a) and 10 seconds (b) at an intensity of 16 mW / cm 2 The precursors were imaged in a ThermoFlexX 20 (Xeikon) after the protective film was stripped off and subsequently developed in a Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 200 mm / min. Drying took place at 60°C within 120 minutes. Then, gloss measurements were performed on the non-printed areas (floor) that were thus formed at certain time intervals. Both plate types were exposed from the back in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 for 15 seconds (a) and 10 seconds (b) at an intensity of 16 mW / cm 2 The precursors were imaged in a ThermoFlexX 20 (Xeikon) after the protective film was stripped off and subsequently developed in a Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 200 mm / min. Drying took place at 60°C within 120 minutes. Then, gloss measurements were performed on the non-printed areas (floor) that were thus formed at certain time intervals. Both plate types were exposed from the back in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 for 15 seconds (a) and 10 seconds (b) at an intensity of 16 mW / cm 2 The precursors were imaged in a ThermoFlexX 20 (Xeikon) after the protective film was stripped off and subsequently developed in a Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 200 mm / min. Drying took place at 60°C within 120 minutes. Then, gloss measurements were performed on the non-printed areas (floor) that were thus formed at certain time intervals. Different re-exposures were performed in a Combi FIII exposure unit at 40°C, in which UVA and UVC exposures were used in parallel and started simultaneously. In the former case, there was a 10-minute UVA exposure (Philips TL 60W / 10-R) at an intensity of 11 mW / cm 2 and a 3-minute UVC exposure (Philips TUV 75W HO G75 T8) at an intensity of 13 mW / cm 2 In the latter case, there was a 10-minute UVA exposure and a 10-minute UVC exposure. Gloss measurements were then performed on the non-printed areas (floor) that were thus formed at certain time intervals.

[0169] Table 3: Gloss after 3 days and flow of printed plates in the case of solvent-based ink (LM)

[0170]

[0171] Table 3 shows the gloss on the surface of the printed plate after 3 days and the inflow of the printed plate after printing with solvent-based ink (LM).

[0172] The gloss values ​​observed were lower in the absence of re-exposure (Example 2a) or in the case of 10 min of UVA and 3 min of UVC re-exposure (Example 2b) than in the case of 10 min of UVA and 10 min of UVC re-exposure (Example 2c). This indicates the presence of MSA on the surface of the substrate. In printing tests, the printing plates from Examples 2a and 2b exhibited reduced inflow.

[0173] Example 3

[0174] a. An SBS-based embossed precursor (1.14 mm thick) was produced on a polyester carrier having 1% by weight paraffin (>C35) as MSA with a melting point of 58°C and 2% by weight benzoyl-α,α-dimethyl acetal (IGM resin BV). Exposure was performed in a Next FV exposure unit (Flint Group) using a fluorescent tube (Light EmissionTech F100T12 / 10-R 100W) at 19 mW / cm². 2 The intensity was such that the relief precursor was exposed from the back for 26 seconds. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently in a Next FV exposure unit (FlintGroup) using a fluorescent tube (Light Emission Tech F100T12 / 10-R 100W) at 19mW / cm². 2 The intensity was exposed through the mask layer for 10 minutes. The precursor was developed in a Flowline Washer FV (Flint Group) using nylosolv A (Flint Group) at a rate of 255 mm / min. Drying occurred at 60°C for 120 minutes. Subsequent exposure occurred at room temperature with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm) 2 The exposures started simultaneously and proceeded in parallel. The UVA exposure time was 10 minutes, and the UVC exposure time increased from 0 minutes to 10 minutes at 2-minute intervals.

[0175] b. A SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support with 1% by weight paraffin (> C35) with a melting point of 58 °C as MSA and 5% by weight benzoin-a,a-dimethyl acetal (IGM Resin B.V.) was exposed from the back in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12 / 10-R 100W) at an intensity of 19 mW / cm 2 for 14 seconds. After the protective film was stripped, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through a mask layer in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12 / 10-R 100W) at an intensity of 19 mW / cm 2 for 8 minutes. In The precursor was developed in a Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) and at a speed of 285 mm / min. Drying occurred at 60 °C within 120 minutes. A further exposure then occurred at room temperature, in which the UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and the UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11 mW / cm 2 ) started simultaneously and were carried out in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was increased from 0 minutes to 10 minutes at 2-minute intervals.

[0176] c. A SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support with 1% by weight paraffin (> C35) with a melting point of 58 °C as MSA and 5% by weight benzoin-a,a-dimethyl acetal (IGM Resin B.V.). This relief precursor was exposed from the back in a Next FV exposure unit (Flint Group) by means of fluorescent tubes (Light Emission Tech F100T12 / 10-R 100W) at an intensity of 19 mW / cm 2 for 26 seconds. After the protective film was stripped, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through a mask layer in a Next FV exposure unit (Flint Group) by means of UV LED strips at 3 x 250 mm / min and an intensity of 800 mW / cm 2 .

[0177] The precursors were developed by means of nylosolv A (Flint Group) and at a rate of 255 mm / min in the Flowline Washer FV (Flint Group). Drying occurred within 120 minutes at 60 °C. Then re-exposure occurred at room temperature, wherein 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 11 mW / cm 2 ) started simultaneously and were carried out in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was increased from 0 minutes to 10 minutes in 2-minute intervals.

[0178] Printing parameters:

[0179] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed by means of a F&K Flexpress 6S / 8 printer (Fischer & Krecke) on a LD-PE film (Delo), which was pre-treated with corona on one side and had a width of 400 mm and a thickness of 55 pm. Lohmann 5.3 foam tape (Lohmann) was used to secure the print board. The screen used had a screen resolution of 420 lines / cm and a volume of 3.5 cm 3 / m 2 . The printing speed was 200 m / min, wherein the lateral feed of the printing unit was 70 pm and the lateral feed of the screen roller was 60 pm. Drying occurred in two stages at 40 °C and 60 °C.

[0180] Table 4: Run-off of printed boards with various ratios of simultaneous UVA and UVC re-exposure

[0181]

[0182] + = no run-off, 0 = little run-off, - = much run-off

[0183] Table 4 shows the evaluation of the run-off of printed boards after printing with solvent-based ink with various ratios of simultaneous UVA and UVC re-exposure. The higher the UVC re-exposure dose applied, i.e. the smaller the ratio of the doses from UVA and UVC re-exposure, the greater the observed run-off of the interstitial spaces of the printed boards. On the other hand, with moderate UVC re-exposure doses, the migration through the MSA largely avoids the run-off of the interstitial spaces.

[0184] Example 4

[0185] MSA Migration

[0186] A 1.14 mm thick SIS-based embossed precursor was produced on a polyester carrier containing 1% by weight paraffin (>C35) with a melting point of 58 °C as the MSA and 5% by weight benzoyl-α,α-dimethyl acetal (IGM resin BV). Exposure was performed in a Combi FIII exposure unit (Flint Group) using a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm². 2 The intensity was such that the relief precursor was exposed from the back for 14 seconds. 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) using a fluorescent tube (Light Emission Tech F100T12 / 10-R 100W) at 19mW / cm². 2 The intensity was exposed through the mask layer for 8 minutes. The precursor was developed in a Flowline Washer FV (Flint Group) using nylosolv A (Flint Group) at a rate of 290 mm / min. Drying occurred at 60°C for 120 minutes. Subsequent exposure occurred at room temperature with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUVTL-D 95W HO SLV / 25, intensity 11mW / cm) 2 The exposures started simultaneously and proceeded in parallel. The UVA exposure time was 8 minutes, and the UVC exposure times were 0 minutes and 2 minutes.

[0187] UV-curable ink printing parameters:

[0188] For printing with Flexocure Force UV-curable inks (Flint Group), an MO4 printing press (Nilpeter) equipped with an FA4 flexographic unit was used. The printing media used were either PE-based self-adhesive label material (Raflatac) with a width of 330 mm and a thickness of 130 μm, or paper-based self-adhesive label material (Raflacoat, UPM) with a width of 330 mm and a thickness of 120 μm. Medium-hardness Tesa blue foam tape (Tesa) was used to secure the printing plate. The anilox rollers used were set to a screen resolution of 500 lines / cm and a 2.5cm... 3 / m 2The volume. The printing speed is 100m / min.

[0189] Table 5: Effects of MSA on PE film or paper when printing with UV-curable inks

[0190]

[0191] Table 5 shows the effect of MSA on PE film or paper when printing with UV-cured inks. With UVC re-exposure, less MSA diffuses onto the surface of the printing plate. When printing on PE film, the absence of MSA results in a reduced full-tone color density; when printing on paper, it results in the appearance of leading edges. Without UVC re-exposure, MSA diffuses onto the surface of the printing plate and facilitates ink transfer to the associated printing medium. When printing on PE film, the presence of MSA results in an increased full-tone color density; when printing on paper, it results in the disappearance of leading edges.

[0192] Example 5

[0193] An SBS-based embossed precursor (1.14 mm thick) was produced on a polyester carrier containing 0.1% or 2.5% paraffin (>C35) by weight as the MSA with a melting point of 58°C and 5% by weight of benzoyl-α,α-dimethyl acetal (IGM resin BV). Exposure was performed in a Combi FIII exposure unit (Flint Group) using a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm². 2 The intensity was such that the relief precursor was exposed from the back 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) using a fluorescent tube (Philips TL 60W / 10-R) at 28mW / cm². 2 The intensity was exposed through the mask layer for 8 minutes. Flowline Washer FV (Flint Group) utilizes Flexosol-i (DuPont) was used as the rinsing medium, and the precursor was developed at a rate of 250 mm / min. Drying occurred at 60°C for 120 minutes. Re-exposure occurred at room temperature with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm) 2) were started simultaneously and carried out in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was 2 minutes.

[0194] Printing conditions:

[0195] A solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a LD-PE film (Delo) pre-treated with corona on one side and having a width of 400 mm and a thickness of 55 pm by means of a F&K Flexpress 6S / 8 printer (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printed board. The screen used was a 420 lines / cm screen resolution and a volume of 3.5 cm 3 / m 2 The printing speed was 200 m / min.

[0196] Table 6:

[0197]

[0198] Very high influx = -

[0199] High influx = -

[0200] Medium influx = 0

[0201] Low influx = +

[0202] No influx = ++

[0203] In reference 5a, a high influx of the board was observed. By adding MSA, the influx was drastically reduced (Example 5b and Example 5c (Table 6)).

[0204] Example 6

[0205] SBS-based relief precursors (thickness 1.14 mm) were produced on a polyester support having 1% by weight of paraffin (> C35) with a melting point of 58°C as MSA and 5% by weight of benzil-a,a-dimethyl acetal (IGM Resins B.V.) and 0%, 0.25% or 0.5% of 1-hydroxycyclohexyl phenyl ketone (CI) or 0.5% of oxypheyl acetic acid 2-[2-oxo-2-phenylacetyloxyethoxy]ethyl ester and oxypheyl acetic acid 2-[2-hydroxyethoxy]ethyl ester (C2) (each from IGM Resins B.V.) mixture. The exposure was carried out in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60W / 10-R) at 28 mW / cm 2The intensity of 22 seconds from the back. After the protective film was peeled off, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60W / 10-R) at an intensity of 28 mW / cm 2 The intensity of 10 minutes through the mask layer. After exposure in a Flowline Washer FV (Flint Group) by means of fluorescent tubes (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11 mW / cm 2 ) started simultaneously and were carried out in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was 2 minutes.

[0206] Printing conditions:

[0207] A solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a LD-PE film (Delo) by means of a F&K Flexpress 6S / 8 printing press (Fischer & Krecke), which was pre-treated with corona on one side and had a width of 400 mm and a thickness of 55 pm. Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The screen used had a screen resolution of 420 lines / cm and a volume of 3.5 cm 3 / m 2 at a printing speed of 200 m / min.

[0208] Table 7:

[0209]

[0210] Very high influx = -

[0211] High influx = -

[0212] Medium influx = 0

[0213] Low influx = +

[0214] No influx = ++

[0215] Significant influx of the plate was observed in the absence of MSA or UVC photoinitiator (reference 6a). The addition of MSA and UVC photoinitiator drastically reduced the influx. In this plate formulation, influx was also reduced by adding 0.5% UVC photoinitiator C2 (Table 7).

[0216] Example 7

[0217] A SIS-based relief precursor (1.14 mm thick) was produced on a polyester carrier containing 1% by weight paraffin (>C35) with a melting point of 58°C as the MSA, 5% by weight benzoyl-α,α-dimethyl acetal (IGM resin BV), and 0%, 0.25%, or 0.5% 1-hydroxycyclohexylphenyl ketone (C1) (IGM resin BV). Exposure was performed in a CombiFIII exposure unit (Flint Group) using a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm². 2 The intensity was such that the relief precursor was exposed from the back for 14 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) using a fluorescent tube (Philips TL 60W / 10-R) at 28mW / cm². 2 The intensity was exposed through the mask layer for 8 minutes. Flowline Washer FV (FlintGroup) utilizes Flexosol-i (DuPont) was used as the rinsing medium, and the precursor was developed at a rate of 150 mm / min. Drying occurred at 60°C for 120 minutes. Re-exposure occurred at room temperature with UVA exposure (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm) 2 They started simultaneously and proceeded in parallel. The UVA exposure time was 8 minutes, and the UVC exposure time was 2 minutes.

[0218] Printing conditions:

[0219] A solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a LD-PE film (Delo) with one side pre-treated with corona and having a width of 400 mm and a thickness of 55 pm by means of a F&K Flexpress 6S / 8 printer (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printed board. The screen used had a screen resolution of 420 lines / cm and a volume of 3.5 cm 3 / m 2 The printing speed was 200 m / min.

[0220] Table 8:

[0221]

[0222] Very high influx = -

[0223] High influx = -

[0224] Medium influx = 0

[0225] Low influx = +

[0226] No influx = ++

[0227] By increasing the UVC photoinitiator content while keeping the UVA photoinitiator content the same, the influx was reduced. With 0.5% of UVC photoinitiator (Example 7c), almost no influx was observed (Table 8).

[0228] Example 8

[0229] SIS-based relief precursors (thickness 1.70 mm) were produced on a polyester support with 1% by weight of paraffin (> C35) having a melting point of 58°C, 5% by weight of benzil-a,a-dimethyl acetal (IGM Resins B.V.) and 0%, 0.25% or 0.5% of 1-hydroxycyclohexyl phenyl ketone (CI) (IGM Resins B.V.). The relief precursors were exposed from the back in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60W / 10-R) at an intensity of 28 mW / cm 2 for 40 seconds. After the protective film was stripped, the precursors were imaged in a CDI 2530 (Esko) and subsequently exposed in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60W / 10-R) at an intensity of 28 mW / cm 2The intensity was exposed through the mask layer for 8 minutes. After The precursor was developed in a Flowline Washer FV (Flint Group) with the aid of nylosolv A (Flint Group) as rinsing medium and at a rate of 230 mm / min. Drying took place at 60°C within 120 minutes. Subsequent exposure at room temperature took place 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 11 mW / cm 2 ) starting simultaneously and running in parallel. The UVA exposure time was 8 minutes and the UVC exposure time was 4 minutes.

[0230] Printing conditions:

[0231] The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a LD-PE film (Delo) with one side pre-treated with corona and having a width of 400 mm and a thickness of 55 pm with the aid of a F&K Flexpress 6S / 8 printer (Fischer & Krecke). Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The screen used had a screen resolution of 420 lines / cm and a volume of 3.5 cm 3 / m 2 . The printing speed was 200 m / min.

[0232] Table 9:

[0233]

[0234] Very high influx = -

[0235] High influx = -

[0236] Medium influx = 0

[0237] Low influx = +

[0238] No influx = ++

[0239] When compared to reference 8a, the influx of the plates was drastically reduced by the addition of MSA and the photoinitiator CI (Example 8b and Example 8c). Further increasing the UVC photoinitiator content from 0.5% (Example 8b) to 1% (Example 8c) did not lead to further improvements regarding the influx (Table 9).

[0240] Example 9

[0241] An SBS-based embossed precursor (1.70 mm thick) was produced on a polyester carrier containing 1% by weight paraffin (>C35) with a melting point of 58°C, 1% by weight benzoyl-α,α-dimethyl acetal (IGM resin BV), and 0%, 0.5%, 1.0%, 1.5%, or 2.0% 1-(4-methylphenyl)-1-dodecanone (C3) (BASF). Exposure was performed in a Combi FIII exposure unit (Flint Group) using a fluorescent tube (Philips TL 60W / 10-R) at 28 mW / cm². 2 The intensity was such that the relief precursor was exposed from the back for 40 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) using a fluorescent tube (Philips TL 60W / 10-R) at 28mW / cm². 2 The intensity was maintained for 9 minutes by exposure to an attached mask layer fixed via vacuum. After removing the mask layer, in Flowline Washer FV (Flint Group) utilizes Flexosol-i (DuPont) was used as the rinsing medium, and the precursor was developed at a rate of 250 mm / min. Drying occurred at 60°C for 120 minutes. Re-exposure occurred at room temperature with UVA exposure (Philips TL 80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D 95W HO SLV / 25, intensity 11mW / cm) 2 The exposures begin simultaneously and proceed in parallel. The UVA exposure time is 10 minutes, and the UVC exposure time is 5 minutes.

[0242] Printing conditions:

[0243] The solvent-based ink FlexitraMV Process Cyan (Flint Group) was printed onto an LD-PE film (Delo) using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). The film had been pre-treated with corona on one side and had a width of 400 mm and a thickness of 55 μm. Lohmann 5.3 foam tape (Lohmann) was used to secure the printing plate. The anilox rollers used were set to a screen resolution of 420 lines / cm and a thickness of 3.5 cm. 3 / m 2of the volume. The printing speed was 200 m / min.

[0244] Table 10:

[0245]

[0246] Very high influx = -

[0247] High influx = -

[0248] Medium influx = 0

[0249] Low influx = +

[0250] No influx = ++

[0251] In reference 9a, a high influx of the plate was observed. By adding MSA and the photoinitiator C3, the influx drastically decreased (Example 9b to Example 9e). From a 1.0% concentration of the UVC photoinitiator C3 (Example 9c), hardly any influx was observed. This was equally true for a further increase of the UVC photoinitiator concentration to 1.5% or 2.0% (Example 9d and Example 9e) (Table 10).

[0252] Example 10

[0253] SIS-based relief precursors (total thickness 1.14 mm) were produced on a polyester support with 1% by weight of paraffin (>C20) with a melting point of 50-57°C as MSA, 2% by weight of benzil-a,a-dimethyl acetal (IGM Resins B.V.) and 0% or 0.5% of 1-hydroxycyclohexyl phenyl ketone (C1) (IGM Resins B.V.) as photoinitiator. In The relief precursors were exposed from the back side in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 at 40°C for 15 minutes by means of a mask layer. After the protective film was peeled off, the precursors were imaged in a ThermoFlexX 20 (Xeikon) and subsequently washed out in a The relief precursors were exposed from the back side in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 80W / 10-R) at 16 mW / cm 2 at 40°C for 15 minutes by means of a mask layer. After the protective film was peeled off, the precursors were imaged in a ThermoFlexX 20 (Xeikon) and subsequently washed out in a Digital Washer FIII (Flint Group) by means of nylosolv A and at a rate of 200 mm / min. Drying occurred at 60°C within 120 minutes. Then the precursors were imaged in a Different re-exposures were performed in the CombiFIII exposure unit, with only UVA (Philips TL 60W / 10-R, intensity 11 mW / cm 2 ) exposure, only UVC (Philips TUV 75W HO G75 T8, intensity 13 mW / cm 2 ) exposure, or with simultaneous UVA and UVC exposure, in each case at 40°C. By simultaneous is meant in this case that both exposures (UVA and UVC) start at the same time. After storage of the developed printing plate for at least one week, contact angle measurements were performed on the printing surface thus formed. The reference used was the surface of pure MSA obtained by melting and subsequent cooling.

[0254] The contact angle is a measure of the wetting of a surface. A uniform wetting of a surface by a liquid (printing ink) is a fundamental prerequisite for a successful printing process. If the wetting is not complete, it will not be possible to transfer the printing forme completely to the printing medium. The 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 droplet of liquid on the surface shows a large 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. With a polar liquid such as water, for example, a large contact angle is expected.

[0255] Table 11 shows the contact angle of a water droplet on the printing plate with or without MSA on the surface of the printing plate. The presence of MSA is controlled by the re-exposure. Pure MSA is used as a reference.

[0256]

[0257] The presence of 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 droplet is much larger than if MSA is not present on the surface. If MSA is present on the surface of the plate (Example 10b, Example 10d and Example 10f), the contact angle of the water droplet is close to 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 thus result in wetting problems when printing with water-based inks. The migration of MSA can be controlled by re-exposure.

[0258] Example 11

[0259] An SBS-based embossed precursor (total thickness 1.14 mm) was produced on a polyester carrier having 1% by weight paraffin (>C20) as MSA with a melting point of 50°C-57°C and 5% by weight benzoyl-α,α-dimethyl acetal (IGM resin BV). The Combi FIII exposure unit (Flint Group) utilizes a fluorescent tube (Philips TL 80W / 10-R) at 16mW / cm². 2 The intensity of the exposure exposed the embossed precursor from the back for 18 seconds. After the protective film was peeled off, the precursor was imaged in a ThermoFlexX 20 (Xeikon) and subsequently... In the Combi FIII exposure unit (Flint Group), a fluorescent tube (Philips TL 80W / 10-R) was used to expose the light at 40°C at 16mW / cm². 2 The intensity was exposed through the mask layer for 15 minutes. The exposed precursor was washed out using a Digital Washer FIII (Flint Group) with nylosolv A at a rate of 220 mm / min. Drying occurred at 60°C for 120 minutes. The printed plate was then... Re-exposed to UVA light in the Combi FIII exposure unit (Philips TL 60W / 10-R, intensity 11mW / cm²). 2 The exposure lasted for 10 minutes, followed by exposure to UVC light (Philips TUV 75W HO G75 T8, intensity 13mW / cm²). 2 The exposure lasted for 5 minutes. Both exposures (UVA and UVC) were initiated simultaneously and performed at 40°C. Contact angle measurements were taken on the resulting printed surface at least one week after development. The reference material used was the surface of pure MSA obtained through melting and subsequent cooling.

[0260] Table 12:

[0261]

[0262] If MSA is present on the surface of the printed circuit board (Example 11b), the contact angle is close to that on pure MSA (Reference 11a). In the case where there is no MSA on the surface of the board (Example 11c), a much smaller contact angle is obtained even when other processing conditions are the same.

[0263] Example 12

[0264] A SBS-based relief precursor (thickness 1.14 mm) was produced on a polyester support with 1 % by weight of paraffin (> C35) with a melting point of 58 °C as MSA and 2 % by weight of benzoin-a,a-dimethyl acetal (IGM Resin B.V.) as MSA. The plate did not contain MSA or contained 1 % by weight of paraffin (> C35) with a melting point of 58 °C or 0.5 % by weight of polysiloxane polyester acrylate (PPA) as MSA. The relief precursor was exposed from the back side in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60W / 10-R) at an intensity of 26 mW / cm 2 for 20 seconds. After the protective film was stripped, the precursor was imaged in a CDI 2530 (Esko) and subsequently exposed through a mask layer in a Combi FIII exposure unit (Flint Group) by means of fluorescent tubes (Philips TL 60W / 10-R) at an intensity of 26 mW / cm 2 for 10 minutes. In the Flowline Washer FV (Flint Group) by means of nylosolv A (Flint Group) and at a rate of 255 mm / min. Drying occurred at 60 °C within 120 minutes. Then re-exposure occurred at room temperature, wherein 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 11 mW / cm 2 ) started simultaneously and were performed in parallel. The UVA exposure time was 10 minutes and the UVC exposure time was 6 minutes.

[0265] Printing conditions:

[0266] For printing with Flexocure Ancora Process Cyan UV-curing ink (Flint Group), a MO4 printing press (Nilpeter) with a FA4 flexo unit was used. The printing medium used was a PE-based self-adhesive label material (Raflatac) that was corona treated on one side or a paper-based self-adhesive label material (Raflacoat, UPM) with a thickness of 120 pm. A Tesa blue foam tape (Tesa) of medium hardness was used to fix the printing plate. The anilox roller used was set with a screen resolution of 500 lines / cm and a volume of 2.5 cm 3 / m 2The volume of the flow was evaluated after about 500 meters of printing. The printing speed was 100 m / min.

[0267] Results:

[0268] Table 13: Flow of the plates after printing on PE film and paper. The re- exposure used: Intensity UVA 7200 mJ / cm 2 ; UVC = 3960 mJ / cm 2 . Ratio of UVA / UVC re-exposure intensity = 1.8.

[0269]

[0270] Table 13 shows the effect of MSA on the flow of the plates when printed with UV-cured ink. Without MSA, a large flow of the mass was observed. By adding paraffin as MSA, the flow of the mass could be drastically reduced. When using polysiloxane polyester acrylate as MSA, a further improvement of the flow was observed.

Claims

1. Process for producing a relief structure for printing with printing inks, comprising the following steps: (i) providing a photopolymerizable relief precursor, the relief precursor comprising: — (A) a dimensionally stable support, — (B) a photopolymerizable relief-forming layer comprising at least a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a mobile surface-active additive, a photoinitiator activatable with UVA light and a photoinitiator activatable with UVC light, (ii) applying a mask or generating a structured mask layer above the photopolymerizable relief-forming layer, (iv-a) exposing the photopolymerizable relief-forming layer to electromagnetic radiation through the mask or mask layer, (v) removing the mask or mask layer, any additional layers that can be present and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv-a), thereby producing a relief, (vii) re-exposing the relief from the side facing away from the support 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 recrosslinked and the permeability of the relief to the mobile surface-active additive is adjusted, for adjusting the surface properties of the relief.

2. Process for producing a relief structure for printing with printing inks, comprising the following steps: (i) providing a photopolymerizable relief precursor, the relief precursor comprising: — (A) a dimensionally stable support, — (B) a photopolymerizable relief-forming layer comprising at least a crosslinkable elastomeric binder, an ethylenically unsaturated monomer, a mobile surface-active additive, a photoinitiator activatable with UVA light and a photoinitiator activatable with UVC light, (iv-b) imagewise exposing the photopolymerizable relief-forming layer to electromagnetic radiation, (v) removing any additional layers that can be present and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv-b), thereby producing a relief, (vii) re-exposing the relief from the side facing away from the support 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 recrosslinked and the permeability of the relief to the mobile surface-active additive is adjusted, for adjusting the surface properties of the relief.

3. The method of claim 1 or claim 2, wherein, 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, consecutively or alternately.

4. The method of claim 1 or claim 2, wherein, The re-exposure conditions are adjusted depending on the type of printing ink, for adjusting the surface properties of the relief to the printing ink.

5. The method of claim 4, wherein, By selection of the re-exposure conditions, the surface properties can be adjusted in such a way that the printing plate is suitable for printing using solvent-based inks, aqueous inks or UV-curing inks. 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, consecutively or alternately. The re-exposure conditions are adjusted depending on the type of printing ink, for adjusting the surface properties of the relief to the printing ink. By selection of the re-exposure conditions, the surface properties can be adjusted in such a way that the printing plate is suitable for printing using solvent-based inks, aqueous inks or UV-curing inks.

6. The method according to any one of claims 1 to 5, characterized in that, The method is performed several times by steps (i) to (viii), wherein in step (vii) the re-exposure to UVA light and / or UVC light varies in terms of dose and / or time sequence of the UVA and UVC re-exposure steps in order to optimize the surface properties of the relief.

7. The method according to any one of claims 1 to 6, characterized in that, The migration of the mobile surface-active additive is controlled by selecting the exposure parameters of the re-exposure steps.

8. The method according to any one of claims 1 to 7, characterized in that, There is re-exposure to UVA light at doses from 100 mJ / cm 2 to 30,000 mJ / cm 2 to 30,000 mJ / cm 9. The method according to any one of claims 1 to 8, characterized in that, There is re-exposure to UVC light at doses from 100 mJ / cm 2 to 20,000 mJ / cm 2 .

10. The method according to any one of claims 1 to 9, characterized in that, The dose ratio (DUVA / DUVC) of UVA light to UVC light is greater than 0.

2.

11. The method according to any one of claims 1 to 10, characterized in that, Due to the lower penetration depth, the surface is exposed to UVC light and exposure to UVA light ensures a stronger cross-linking throughout the layer.

12. The method of any one of claims 1 to 11, wherein, The method comprises: The generated relief is re-exposed from the side facing away from the carrier layer to UVA light in the wavelength range from 315 nm to 380 nm.

13. The method of any one of claims 1 to 12, wherein, The method comprises: The generated relief is re-exposed from the side facing away from the carrier layer to UVA light in the wavelength range from 315 nm to 380 nm and to UVC light in the wavelength range from 200 nm to 280 nm.

14. The method of claim 11, wherein, Due to the lower penetration depth, the surface is exposed to UVC light in the wavelength range from 200 nm to 280 nm and exposure to UVA light in the wavelength range from 315 nm to 380 nm ensures a stronger cross-linking throughout the layer.

15. The method of claim 4, wherein, The printing ink is a hydrophilic ink.

16. The method of any one of claims 1 to 15, wherein, The printing ink is a hydrophilic printing ink and wherein the exposure conditions of the re-exposure steps are adjusted to UVC light or to UVC light and UVA light to facilitate wetting of the surface of the relief with the hydrophilic printing ink.

17. The method of claim 4, wherein, The printing ink is a hydrophilic ink.

18. The method of claim 17, wherein, The printing ink is a hydrophilic printing ink and wherein the exposure conditions of the re-exposure steps are adjusted to UVC light or to UVC light and UVA light to facilitate wetting of the surface of the relief with the hydrophilic printing ink.

19. The method of any one of claims 1 to 18, wherein, The printing ink is a hydrophilic ink. The printing ink is a hydrophilic printing ink and wherein the exposure conditions of the re-exposure steps are adjusted to UVC light or to UVC light and UVA light to facilitate wetting of the surface of the relief with the hydrophilic printing ink. The non-photopolymerized regions of the relief-forming layer are removed by treatment with a rinsing medium or by heat treatment.

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