Photopolymerizable relief precursor with adjustable surface properties

Abstract

The objective of the present invention is to provide a "switchable" printing plate whose surface characteristics can be adjusted by exposure parameters, so that the same printing plate can be used universally in different application fields. [Solution] A photopolymerizable relief precursor comprising: (A) a dimensionally stable carrier, and (B) a photopolymerizable relief-forming layer comprising at least a crosslinkable elastomer binder, an ethylenically unsaturated monomer, a mobile surface-active additive, a UVA-activated photoinitiator, and a UVC-activated photoinitiator. The present invention further relates to a method for producing a relief structure.

Description

[Technical Field]

[0001] The present invention relates to a photopolymerizable relief precursor having surface properties that can be adjusted by exposure conditions, a method for generating a relief structure from the relief precursor, the relief structure itself, and its use. [Background technology]

[0002] Printing with solvent-based inks requires a printing plate with an ink-replenishing surface to prevent ink from flowing into the interstitial spaces between screen dots. This is typically achieved by the presence of a movable surface-active additive (MSA) in the relief layer, which reduces the surface tension of the printing surface. However, the presence of this additive can be problematic when printing with UV-curing or aqueous inks, for example, because it can lead to insufficient ink transfer in solid areas. Therefore, various printing plates are used for printing with solvent-based inks, UV-curing inks, or aqueous inks. Examples of such printing plates are shown in European Patent Application Publication No. 1014194, but such plates are only suitable for specific types of solvent-based inks. [Overview of the project] [Problems that the invention aims to solve]

[0003] The object of the present invention is to provide a printing plate that is "switchable" so that its surface properties can be adjusted by exposure parameters, enabling the same printing plate to be used universally in different application fields. The requirements for printing plates printed with solvent-based inks are different from those for printing plates printed with UV-curing or water-based inks. [Means for solving the problem]

[0004] This objective is achieved with a photopolymerizable relief precursor that includes the following: (A) Dimensionally stable carrier, (B) A photopolymerizable relief-forming layer comprising at least a crosslinkable elastomer binder, an ethylenically unsaturated monomer, a mobile surfactant, a UVA-activated photoinitiator, and a UVC-activated photoinitiator. [Effects of the Invention]

[0005] The relief precursor according to the present invention allows for control of the migration of MSA to the surface through the selection of exposure parameters. It is assumed that the MSA tends to diffuse to the surface of the relief layer, thereby making this surface hydrophobic. Exposure to UVA light to deeper penetration depths ensures greater crosslinking throughout the relief layer and stabilizes the entire relief. Exposure to UVC light results in shallower penetration depth into the photoactive layer, ensuring excellent recrosslinking of still-present monomers and polymers. This reduces or prevents the migration of MSA to the surface of the relief, resulting in a more hydrophilic surface. This allows the printed area to be wetted with hydrophilic printing inks. UVC exposure may also induce oxidation of the formulation components, leading to the formation of polar and hydrophilic groups.

[0006] The relief precursor according to the present invention, used as a printing plate, enables the realization of, in particular, the following advantages.

[0007] Surface properties can be adjusted to prevent or reduce the inflow of solvent-based ink into the gaps between screen dots during printing. This increases the printing time before the plate needs cleaning.

[0008] By adjusting the surface properties, the stickiness of the surface and therefore the tendency for dust and dirt to accumulate on the surface can be reduced.

[0009] The same printing plate can be used to print with various types of inks, as its surface properties can be adjusted by selecting re-exposure conditions to make it suitable for printing with solvent-based inks, water-based inks, or UV-curing inks. [Brief explanation of the drawing]

[0010] [Figure 1] This shows the change in gloss in gloss units (GU) as a function of various re-exposure times in days. [Figure 2] This shows the change in gloss in gloss units (GU) as a function of various re-exposure times in days. [Figure 3] This shows the change in gloss in gloss units (GU) as a function of various re-exposure times in days. [Figure 4] The integrals of the IR bands at 719 and 729 cm⁻¹ after 7 days with a predetermined re-exposure time are shown. [Figure 5] The integrals of the IR bands at 719 and 729 cm⁻¹ after 7 days with a predetermined re-exposure time are shown. [Figure 6] The integrals of the IR bands at 719 and 729 cm⁻¹ after 7 days with a predetermined re-exposure time are shown. [Modes for carrying out the invention]

[0011] Dimensionally stable carrier materials that can optionally have additional layers can be used as dimensionally stable carriers (A). Examples of suitable dimensionally stable carriers include plates, films, conical and cylindrical sleeves made of metals such as steel, aluminum, copper, and nickel, or plastics such as polyethylene terephthalate, polybutylene terephthalate, polyamide, and polycarbonate, or sleeves made of woven and nonwoven fabrics (or composite materials made from glass fiber and plastic). Particularly suitable dimensionally stable carriers are dimensionally stable carrier films or metal sheets, such as polyethylene films or polyester films, steel plates, or aluminum sheets. These carrier films generally have a thickness of 50 to 1100 μm, preferably 75 to 400 μm, for example, about 250 μm. When using plastic films, their thickness is in the range of 100 to 200 μm, preferably 125 to 175 μm. When using steel as the carrier material, steel plates with a thickness of 0.05 to 0.3 mm are preferred. Tin-plated steel plates are preferred to prevent corrosion. These carrier films or carrier sheets can be coated with a thin adhesion-promoting layer, for example, a layer with a thickness of 0.05 to 5 μm, on the side of the carrier film facing the substrate layer. This adhesion layer may consist of, for example, a mixture of polycarbonate, phenoxy resin, and a multifunctional isocyanate.

[0012] These carrier films or carrier sheets already have a thin adhesion promoter layer (AH), or can have one provided. The adhesive layer can be a polyurethane adhesive varnish (for example, in accordance with German Patent Application Publication No. 3045516) based on a polyisocyanate crosslinked polyether varnish or polyester varnish with a layer thickness of 0.5 to 50 μm, particularly 2 to 30 μm.

[0013] An additional adhesion-promoting intermediate layer (AH) may be present on the opposite side of the carrier layer of the adhesive layer. The thickness of these layers is 0.1 to 50 μm, particularly 1 to 10 μm, and can be obtained, for example, from diluted aqueous alcohol solutions of partially (e.g., up to 80 mol%) hydrolyzed polyvinyl esters, phenylglyceryl ether monoacrylate, and glyoxal, accompanied by drying and baking.

[0014] The adhesion-promoting layer or intermediate layer aims to enhance adhesion between individual layers and stabilize the layer structure. This requires the selection of a material that can establish interaction with both layers. Preferred examples include surfactants, amphiphilic molecules and block copolymers having hydrophobic and hydrophilic regions, and oligomers containing blocks compatible with both layers or polymers within the layers. The adhesion strength between the dimensionally stable carrier (A) and the relief-forming layer (B) should exceed 0.5 N / cm when measured in a peel test at a peel angle of 90° and a peel speed of 30 mm / min.

[0015] The relief precursor comprises at least one photopolymerizable relief-forming layer (B). The photopolymerizable relief-forming layer can be coated directly onto the carrier. However, other layers, such as an adhesive layer or an elastic or compressible underlayer, may be present between the carrier and the relief-forming layer.

[0016] The relief-forming layer (B) may also consist of multiple layers, in which case it generally comprises 2 to 30 layers, preferably 2 to 5 layers, more preferably 2 to 3 layers, and very preferably 2 layers. The layers may contain the same or different components in the same or different proportions. Preferably, these layers contain the same components. Preferably, the relief-forming layer closest to the carrier layer is already fixed, crosslinked, and / or reacted. Relief-forming layers are placed on these fixed, crosslinked, and / or reacted layers, which may also be fixed, crosslinked, or reacted.

[0017] Those skilled in the art know of elastomer binders for producing relief-forming layers of flexographic elements. Examples include styrene-diene block copolymers, natural rubber, polybutadiene, polyisoprene, styrene-butadiene rubber, nitrile-butadiene rubber, butyl rubber, styrene-isoprene rubber, styrene-butadiene-isoprene rubber, polynorbornene rubber, or ethylene-propylene-diene rubber (EPDM). The use of hydrophobic binders is preferred. Such binders are soluble in organic solvents or mixtures thereof.

[0018] Preferably, the elastomer is a thermoplastic elastomer block copolymer of an alkenyl aromatic compound and a 1,3-diene. The block copolymer can be linear, branched, or radial. Typically, they are type ABA triblock copolymers, but type AB diblock copolymers, or those with alternating elastomer blocks and thermoplastic blocks, e.g., ABABA, are also possible. Mixtures of two or more different block copolymers can also be used. Commercially available triblock copolymers often contain a specific proportion of diblock copolymer. The diene units can be linked to 1,2, or 1,4. Both styrene-butadiene or styrene-isoprene type block copolymers and styrene-butadiene-isoprene type block copolymers can be used. These are commercially available, for example, under the name Kraton®. Thermoplastic elastomer block copolymers with styrene terminal blocks and statistical styrene-butadiene intermediate blocks can also be used. Block copolymers can also be fully or partially hydrogenated, such as SEBS rubber. Preferred elastomer binders are triblock copolymers of type ABA or radial block copolymers of type (AB)n (where A is styrene and B is diene), and statistical and random copolymers of styrene and diene.

[0019] In preferred embodiments of the present invention, the thermoplastic elastomer binder comprises at least one styrene-isoprene block copolymer, particularly a styrene-isoprene-styrene block copolymer, thereby the polymer may also contain a certain proportion of diblock styrene-isoprene copolymer. Preferred styrene-isoprene type binders generally contain 10-30% by weight, preferably 12-28% by weight, and more preferably 13-25% by weight of styrene. In further embodiments, the binder is a styrene-butadiene-styrene (SBS) block copolymer. Preferred SBS polymers generally contain 20-35% by weight, preferably 22-33% by weight, and more preferably 24-31% by weight of styrene. These block copolymers generally have an average molecular weight (MW) of 100,000-300,000 g / mol. Of course, mixtures of different styrene-isoprene block copolymers or styrene-butadiene block copolymers can also be used.

[0020] In a second embodiment of the present invention, radial isoprene-styrene block copolymers can be used preferentially. The isoprene and / or butadiene units in the polyisoprene block may be bonded to 1,4 with the remaining double bonds located in the chain, or bonded to 3,4 with the remaining double bonds located in the pendants. Block copolymers having essentially 1,4 bonds and binders having a specific ratio of 3,4 bonds can be used. The pendant vinyl groups in binders having 3,4-bond units preferably react during the crosslinking process of the photopolymerizable layer, resulting in the production of plates with a high degree of crosslinking. For example, block copolymers with a vinyl group content of 20-70% can be used.

[0021] In preferred embodiments of the present invention, radial styrene-isoprene copolymers having a vinyl group content of less than 10% can be used. In a second preferred embodiment of the present invention, a mixture of two different styrene-isoprene block copolymers is used. Preferably, one of them has a vinyl group content of at least 20%, particularly 20-70%, preferably 25-45%. The other has a low vinyl group content, which may be, for example, less than 10%. Alternatively, a mixture of two styrene-isoprene copolymers can be used, one having a high diblock fraction of more than 40% by weight, and the other having a lower diblock fraction of less than 30% by weight. In addition to the thermoplastic elastomer block copolymers, particularly styrene-isoprene block copolymers, the photopolymerizable layer may also contain a further elastomer binder different from the block copolymer. Such additional binders, also called secondary binders, allow for modification of the properties of the photopolymerizable layer. Vinyltoluene-α-methylstyrene copolymer is an example of a secondary binder. Generally, the amount of such secondary binder should not exceed 25% by weight, based on the total amount of all binders used. Preferably, the amount of such secondary binder should not exceed 15% by weight, more preferably 10% by weight. The total amount of binder is generally 30-90% by weight, preferably 40-85% by weight, more preferably 60-85% by weight, based on the total amount of all components of the relief-forming layer.

[0022] For relief precursors that can be developed in aqueous solutions, water-soluble, swelling, dispersible, or emulsifying polymers are used. In addition to polyvinyl acetate that is completely or partially hydrolyzed, polyvinyl alcohol, polyvinyl acetal, polystyrene sulfonate, polyurethane, polyamide (such as those described in European Patent Publication No. 0085472 or German Patent Publication No. 1522444) and any combination thereof can be used. Examples of such polymers are described in European Patent Publication No. 0079514, European Patent Publication No. 0224164, or European Patent Publication No. 0059988. These polymers may be linear, branched, star-shaped, or dendritic, and may exist as homopolymers, statistical copolymers, block copolymers, or alternating copolymers. Very often, the described polymers have functional groups that can increase solubility and / or participate in crosslinking reactions. These groups include, for example, carboxyl, SO3, OH, thiol, ethylenically unsaturated, (meth)acrylate and epoxide groups, as well as any combination thereof.

[0023] In the case of the relief-forming layer (B), the total amount of binder is generally 30 to 90% by weight, preferably 40 to 85% by weight, and more preferably 45 to 85% by weight, based on the sum of all components of the relief-forming layer.

[0024] The relief-forming layer (B) may contain further components selected from the group consisting of: plasticizers, solvents, other binders, colorants, stabilizers, modifiers, UV absorbers, dispersing aids, crosslinking agents, viscosity modifiers, surfactants, and any combination thereof. These additives, auxiliaries, and adjuvants are included in the radiosensitive mixture at an overall concentration of 0.001 to 60% by weight, preferably 0.01 to 50% by weight, more preferably 0.1 to 50% by weight, and very preferably 1 to 50% by weight, based on the whole formulation. Individual additives are included at a concentration of 0.001 to 40% by weight, preferably 0.01 to 40% by weight, more preferably 0.1 to 40% by weight, and very preferably 0.1 to 35% by weight, based on the whole formulation.

[0025] The photopolymerizable relief cleft (B) also comprises, in known ways, at least one ethylenically unsaturated monomer compatible with a binder or multiple binders. The ethylenically unsaturated monomer may 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 below. Monomers that have been found to be particularly advantageous are esters or amides of acrylic acid or methacrylic acid having monofunctional or polyfunctional alcohols, amines, amino alcohols or hydroxy ethers and esters, esters of fumaric acid or maleic acid, vinyl ethers, vinyl esters and allyl compounds.

[0026] Generally, these monomers are not gaseous compounds at room temperature. Preferably, ethylenically unsaturated monomers contain at least two ethylenically unsaturated groups, more preferably 2 to 10 ethylenically unsaturated groups, and very preferably 2 to 6 ethylenically unsaturated groups. Compounds having a CC triple bond can also be used in radiosensitive mixtures. Preferably, the ethylenically unsaturated groups are at least acrylate and / or methacrylate groups, but styrene derivatives, acrylamides, vinyl esters and vinyl ethers can also be used. Ethylene-unsaturated monomers generally have a molecular weight of 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 especially less than 300 g / mol.

[0027] Possible examples include derivatives of acrylic or methacrylic acid, such as esters with monohydric or polyhydric alcohols, for example, acrylic or methacrylic acid esters of alkanols having 1 to 20 carbon atoms (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, etc.), and (meth)acrylic esters 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) The compound includes acrylates, 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, di-, tri- and tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate or pentaerythritol tetra(meth)acrylate, as well as poly(ethylene oxide) di(meth)acrylate, m-methylpoly-(ethylene oxide)-yl-(meth)acrylate, N,N-diethylaminoethyl acrylate, 1 mole of glycerin, 1 mole of epichlorohydrin, 3 moles of reaction products from acrylic acid and glycidyl methacrylate, and bisphenol A diglycidyl ether acrylate.

[0028] Derivatives of acrylamide and methacrylamide, such as ethers of their N-methylol derivatives with monohydric and polyhydric alcohols (e.g., ethylene glycol, glycerin, 1,1,1-trimethylolpropane, oligomers, or polymeric ethylene oxide derivatives), are also suitable. These are particularly suitable when polyamide or polyvinyl alcohol is used as a binder.

[0029] Suitable alternatives include those known as epoxy and urethane (meth)acrylates, such as those obtained by the reaction of bisphenol A diglycidyl ether with (meth)acrylic acid, or by the reaction of diisosinate with hydroxyalkyl (meth)acrylate or polyester or polyether containing hydroxyl groups. Other olefinically unsaturated compounds that can be used include esters of acrylic acid or methacrylic acid, especially those with low vapor pressure, and those modified with compatibilizers, for example, with hydroxyl, amide, sulfonated ester, or sulfonamide groups. Mixtures of the above copolymerizable ethylenically unsaturated organic compounds can also be used.

[0030] 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, di-, tri- and tetraethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

[0031] In one embodiment, the ethylenically unsaturated monomer is included in the formulation at a concentration of 0.5 to 60% by weight, preferably 1 to 50% by weight, more preferably 1 to 40% by weight, and very preferably 2 to 40% by weight, based on the overall composition.

[0032] The photopolymerizable relief-forming layer also includes a movable surface-active additive.

[0033] Preferred mobile and surface-active additives are selected from the group consisting of ionic or nonionic surfactants, long-chain hydrocarbons, waxes, especially paraffin waxes, organosilicon compounds, especially 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 in the above class are available under the following trade names: Polyvest ST-E100, Silicon Glide T-41, Silicon Glide T-57, AFCONA-3700, Silicon F.1000, Silicon F.60000, Rad2010, Rad2200N, Rad2300, Rad2500, Rad2700, Rad2800, Miramer SIU2400, X-22-2445, X-22-174BX, KBM-5103, X-22-161B, KF-8010, Silmer OH ACR C50, Silmer OH ACR Di-400, Silmer ACR Di-10, Silmer OH ACR D4, AFCONA-3835, and Sartomer CN9800.

[0034] In one preferred embodiment, the movable surface additive is paraffin wax. Branched and / or unbranched paraffin waxes with a chain length of more than 15 carbon atoms, more preferably more than 20 carbon atoms, and very preferably more than 30 carbon atoms are preferred. Chain lengths in the 20-40 carbon atom range are also preferred.

[0035] The photopolymerizable relief-forming layer also contains a photoinitiator that can be activated by UVA light and a photoinitiator that can be activated by UVC light.

[0036] Preferred photoinitiators that can be activated by UVA light are selected from the group consisting of benzyl ketals, acylphosphine oxides, bisacylphosphine oxides, aminophenyl ketones, phenyl oxime esters, and mixtures thereof.

[0037] Preferred photoinitiators that can be activated by UVC light are selected from the group consisting of hydroxyphenyl ketones, benzoyl formate, benzophenone, arylalkyl ketones, arylbenzyl ketones, and mixtures thereof.

[0038] In one particularly preferred embodiment, the UVA-activated photoinitiator is selected from the group consisting of diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, benzyldimethyl ketal, and benzyldiethyl ketal, and the UVC-activated photoinitiator is selected from the group consisting of 2-[2-oxo-2-phenylacetoxy-ethoxy]ethyl oxyphenylacetate, 2-[2-hydroxyethoxy]ethyl oxyphenylacetate, methylbenzoyl formate, p-tolyluundecylketone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one and mixtures thereof.

[0039] The movable surface-active additive is generally present 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.

[0040] A UVA-activated photoinitiator is generally present in the photopolymerizable relief 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 layer.

[0041] The UVC light-activated photoinitiator is generally present in the photopolymerizable relief 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 photopolymerizable relief layer.

[0042] Generally, the mass ratio of a photoinitiator activatable with UVA light to a photoinitiator 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.

[0043] Generally, the ratio of the amount of UVA-activated photoinitiator to the amount of mobile surface-active additive is 0.01 to 10, preferably 0.1 to 5, and more preferably 0.1 to 3.

[0044] The photopolymerizable relief precursor according to the present invention may represent one or more further layers selected from the group consisting of: an adhesive layer and / or compressible layer between the carrier layer and the relief-forming layer; a functional layer placed on top of the relief-forming layer, such as a structure-giving layer, a barrier layer, a cover layer, a digitally reproducible mask layer; and two or more combinations of these layers.

[0045] For example, a photopolymerizable relief precursor may have an intermediate layer, preferably an adhesive layer and / or a compressible layer, between the carrier layer and the photopolymerizable relief-forming layer.

[0046] The photopolymerizable relief precursor may exhibit further layers selected from the group consisting of a mask layer, a barrier layer, a cover layer, and two or more combinations thereof, on the side of the photopolymerizable relief-forming layer opposite to the carrier layer.

[0047] In one preferred embodiment, the photopolymerizable relief precursor includes: (A) A dimensionally stable carrier; (AH) Optional adhesion-promoting layer; (B) A photopolymerizable relief-forming layer comprising at least a crosslinkable elastomer binder, an ethylenically unsaturated monomer, a mobile surface-active additive, a UVA-activated photoinitiator, and a UVC-activated photoinitiator; (C) A laser abrasive mask layer comprising at least a non-radical crosslinkable elastic polymer, a UVA light absorbing material, and an IR light absorbing material; and optionally (D) A removable cover layer.

[0048] The relief precursor according to the present invention preferably includes a laser-abradable mask layer (C) placed on a relief-forming layer (B), which can be removed using a solvent or by heating and adsorption / absorption. This layer is heated and volatilized by selective irradiation with high-energy electromagnetic radiation, thereby generating a mask with image-specific structures that are used to transfer the structures to the relief precursor. To this end, the layer must be impermeable in the UV range, absorb radiation in the VIS-IR range, and be heated and ablated.

[0049] The optical density of the mask layer in the UV range of 330-420 nm is in the range of 1-5, more preferably 1.5-4, and very preferably 2-4. The optical density is determined by measuring it using an X-rite361TX densitometer with the "density" setting using a UV filter.

[0050] The layer thickness M of the laser-abradable mask layer (C) is generally 0.1 μm to 5 μm. If the layer thickness is less than 0.1 μm, it is difficult to achieve sufficient optical density. If the layer thickness exceeds 5 μm, the laser sensitivity of the element is too low, requiring long laser times for imaging. The layer thickness is preferably 0.3 μm to 4 μm, particularly 1 μm to 3 μm. (Laser sensitivity of the mask layer (1 cm of the layer)) 2 The energy required to ablate the substance (measured as 0.1-10 J / cm²) is 0.1-10 J / cm². 2 Preferably 0.3 to 5 J / cm 2 , more preferably 0.5~5J / cm 2It needs to be that way.

[0051] The mask layer (C) contains at least one non-radical crosslinkable elastic polymer that can uniformly disperse components that absorb electromagnetic radiation and are ablated as efficiently as possible when heated. The elastic polymer may be a linear, branched, star-shaped, comb-shaped, or dendritic homopolymer or copolymer. The copolymer may exist as a statistical and / or block copolymer. The elastic polymer may also be a mixture of polymers that differ, for example, in structure, monomer composition, block length, molecular weight, functional groups, their number and / or distribution. Mixtures of polymers may also be used.

[0052] Examples of non-radical crosslinkable elastic polymers that are very suitable for the mask layer (C) include: ethylene vinyl acetate, flexible elastic polyamide, flexible elastic polyurethane, nitrocellulose, poly(vinyl butyral-vinyl alcohol) copolymer (or poly(vinyl butyral vinyl ethyl-vinyl alcohol) copolymer, and other polyvinyl acetals. Of course, other flexible elastic materials such as partially hydrolyzed polyvinyl acetate can also be used as binders. Preferred binders for the mask layer (C) are flexible elastic polyamide, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, or partially hydrolyzed polyvinyl acetal.

[0053] This mask layer (C) may be permeable or impermeable to oxygen.

[0054] Generally, the relief-forming layer (B) and the abradable mask layer (C) are soluble in common commercially available washout media, which generally consist of solvent mixtures or aqueous solutions. These washout media consist primarily of one or more nonpolar hydrocarbon solvents, with secondary components being moderately polar alcohols such as benzyl alcohol, n-pentanol, cyclohexanol, ethylhexanol, and heptyl alcohol. The aqueous solutions typically contain surfactants and / or flocculants and generally have a pH > 7. The relief-forming layer (C) can usually be treated with these washout media.

[0055] Furthermore, the relief-forming layer (B) and the abradable mask layer (C) can also be thermally developed or removed (see, for example, European Patent Application Publication No. 1239329 or European Patent Application Publication No. 1170121). In this case, following exposure for each image, the relief structure is heated to a softening or melting temperature. This causes the unexposed and non-crosslinked areas of the relief structure to become partially tacky with liquid and are continuously removed by suction (absorption) by a nonwoven or woven fabric.

[0056] In further embodiments, an additional oxygen-impermeable layer (E) is present between layers (B) and (C) of the relief precursor according to the present invention. When the oxygen-impermeable layer (E) is present, layers (B) and / or (C) are preferably permeable to oxygen. The thickness of layer (E) here is in the range of 3 to 5 μm. In addition to the auxiliary agent, this layer mainly comprises one or more elastic polymers having low oxygen permeability, their oxygen permeability being 1.5 × 10⁻⁶. 5 cm 3 ·μm / (m 2 The value is less than or equal to d·bar. The polymer in layer (E) is preferably also non-radical crosslinkable.

[0057] Suitable elastic polymers that can be thermally developed and / or soluble in organic solvents and have a sufficient barrier effect against oxygen include partially hydrolyzed polyvinyl acetate, ethylene-vinyl acetate copolymers and ethylene-vinyl alcohol copolymers, and ethylene-vinyl acetate-vinyl alcohol copolymers, having a degree of hydrolysis from 30 to a maximum of 80 mol%. Also very suitable are cyclic acetals of polyvinyl alcohol such as polyvinyl butyral, polyvinyl ethyl, polyvinyl formal, and polyvinyl propyral, and copolymers containing two or more different vinyl acetal units selected from vinyl formal, vinyl ethyl, vinyl propyral, and vinyl butyral units. Since the reaction of polyvinyl alcohol to a complete acetal is incomplete for statistical and steric reasons, polyvinyl acetals are always copolymers with vinyl alcohol units. Thus, precisely, poly(vinyl butyral) is poly(vinyl butyral-vinyl alcohol). The residual OH content of the described polyvinyl acetals is usually 10-30% by weight. For example, vinylethyl-vinylbutyral-vinyl alcohol copolymer (poly(vinylethyl-vinylbutyral)) is very suitable.

[0058] The object of the present invention is also a method for manufacturing a relief structure, comprising the following steps: (i) Providing a photopolymerizable relief precursor comprising at least one movable surface-active additive, (ii) Application of a mask onto the photopolymerizable relief-forming layer, or generation of a structured mask layer, (iii) Optionally, exposure of the back surface to electromagnetic radiation via the carrier layer, (iv-a) Exposure of the photopolymerizable relief-forming layer to electromagnetic radiation, preferably in the wavelength range of 315 to 380 nm, via the mask or the mask layer. (v) Removal of the mask or the mask layer, any further layers, and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv), thereby generating a relief. (vi) Optionally, drying of the relief, (vii) Re-exposure of the relief from the side opposite to the carrier layer to UVA light in the wavelength range of 315-380 nm and / or UVC light in the wavelength range of 200-280 nm, thereby re-crosslinking the relief to adjust the surface properties of the relief, preferably to use a specific printing ink, and adjusting the permeability of the movable surface active additive. (viii) Optional, further processing steps.

[0059] An object of the present invention is further a method for manufacturing a relief structure having the following steps: (i) Providing a photopolymerizable relief precursor comprising at least one movable surface-active additive, (iii) Optionally, exposure of the back surface to electromagnetic radiation via the carrier layer, (iv-b) Image exposure of the photopolymerizable relief forming layer to electromagnetic radiation preferably in the wavelength range of 315 to 380 nm, (v) Further layers if present, and removal of non-photopolymerized regions of the relief-forming layer not exposed in step (iv), thus generating a relief. (vi) Optionally, drying of the relief, (vii) Re-exposure of the relief from the side opposite to the carrier layer to UVA light in the wavelength range of 315-380 nm and / or UVC light in the wavelength range of 200-280 nm, thereby re-crosslinking the relief to adjust the surface properties of the relief, preferably to use a specific printing ink, and adjusting the permeability of the movable surface active additive. (viii) Optional, further processing steps.

[0060] In a preferred embodiment, the re-exposure in step (vii) is performed with UVA and UVC light. The re-exposure with UVA and UVC light can be performed at the same time (simultaneously) or sequentially (alternately).

[0061] In the case of re-exposure to UVA light, this is typically 100-30,000 mJ / cm². 2It is carried out with a dose of UVA light. UVA light of 100~20,000 mJ / cm 2 is preferred, UVA light of 100~7,000 mJ / cm 2 is more preferred, and UVA light of 500~7,000 mJ / cm 2 is highly preferred.

[0062] In the case of re-exposure to UVC light, this is usually carried out with a dose of UVC light of 100~20,000 mJ / cm 2 UVC light. UVC light of 100~20,000 mJ / cm 2 is preferred, UVC light of 100~8,000 mJ / cm 2 is more preferred, and UVC light of 500~8,000 mJ / cm 2 is highly preferred.

[0063] Re-exposure to UVA light and UVC light can occur simultaneously, continuously, or alternately, whereby the ratio (D UVA / D UVC ) of the dose of UVA to UVC light is generally greater than 0.2, preferably greater than 0.4, more preferably greater than 0.6, and highly preferably greater than 0.8. Due to the shallow penetration depth, exposure to UVC light preferably seals the surface of the layer, while exposure to UVA light ensures stronger cross-linking throughout the layer, resulting in a mechanically stable relief.

[0064] In the first step (i), the aforementioned relief precursor is provided. It can be optionally washed, in which case, all techniques well known to those skilled in the art can be used, such as brushing, blowing, wiping (with and without solvent), rinsing, and any desired combination thereof.

[0065] The wavelength of the irradiated electromagnetic radiation is in the range of 200 to 2,000 nm, preferably the UV range, more preferably the range of 200 to 550 nm, and very preferably the range of 300 to 450 nm. In addition to broadband irradiation of electromagnetic waves, it may be advantageous to use a narrowband or monochromatic wavelength range of the kind that can be generated using a corresponding filter, laser, or light-emitting diode (LED). In these cases, preferred wavelengths are in the range of 350, 365, 385, 395, 400, 405, 532, 830, and 1064 nm, individually (and about 5 to 10 nm above and / or below) or in combination.

[0066] If a cover layer (D) is present, it is removed. Preferably, the cover layer is a protective film and is peeled off.

[0067] In step (ii), the mask layer is imaged by either removing the layer and / or making positionally resolved changes to its absorption and / or reflectivity, such that the mask layer becomes at least partially transparent in the wavelength range used for imaging. The mask layer is preferably ablated with a high-energy laser, the laser beam guided onto the mask layer under computer control. In this case, the IR laser mainly used has a wavelength in the range of 500 to 20,000 nm, preferably in the range of 800 to 10,000 nm, and more preferably in the range of 1,000 to 2,000 nm. Wavelengths of about 830 nm, 980 nm, 1064 nm, and 10.6 μm, or combinations thereof, are particularly preferred.

[0068] In an optional step (iii), the relief precursor can be broadly irradiated with electromagnetic radiation from at least one side. This irradiation is preferably performed from the side of the relief precursor opposite the mask layer in order to achieve fixation (backside exposure) of the resulting relief structure. This backside exposure is preferably performed through a transparent and dimensionally stable material as a carrier material, such as a polymer film, particularly a polyester film. If an opaque carrier material is used, step (iii) is omitted.

[0069] Exposure of the relief precursor according to the present invention to electromagnetic radiation in step (iv-a) through layer (C) and optionally layer (E) induces a reaction in the region of layer (B) beneath the exposed region (C) of layer, which leads to crosslinking of the components present in the layer. As a result of this crosslinking, these regions are stabilized and cannot be removed in the subsequent development step. Irradiation is generally broad, but can instead be performed on a small area (substantially dot-like) by a guided laser beam or position-resolved projection of electromagnetic radiation. The electromagnetic radiation used for this exposure generally has a wavelength in the range of 200 to 2,000 nm, preferably in the range of 315 to 380 nm.

[0070] Irradiation here can be continuous, pulsed, or carried out over multiple short periods using continuous radiation. The intensity of the radiation here can vary over a wide range to ensure that a sufficient dose is used to bridge layer (B) for the subsequent development step. The intensity of the radiation is generally 10–1,000 mW / cm². 2 This is within the range. Radiation levels are generally 3-100 J / cm². 2 The range is preferably 6 to 20 J / cm². 2 This is within the range. Exposure to the energy source can also be carried out, for example, in an inert atmosphere such as a noble gas, CO2 and / or nitrogen, or under a liquid that does not damage the multilayer elements.

[0071] Direct imaging exposure can be achieved by selectively exposing the crosslinked region. This can be achieved, for example, with one or more laser beams controlled accordingly (through the use of a screen in which specific pixels emitting radiation are activated, through the use of a mobile LED strip, through an LED array in which individual LEDs are intentionally switched on and off, through the use of an electronically controllable mask in which pixels allowing radiation from a radiation source to pass through are made transparent, through the use of a projection system in which pixels are exposed to radiation from a radiation source via the orientation of a corresponding mirror, or a combination thereof). Direct exposure by a projection system with controlled laser beams or mirrors is preferred, where the absorption spectrum of the initiator or initiator system and the emission spectrum of the radiation source must overlap at least partially.

[0072] In step (v), layer (C), and layer (E) if present, and the non-crosslinked regions of layer (B) are removed to create a relief. In step (v), the unexposed, non-photopolymerized regions of the relief-forming layer can be removed by treatment with a washout medium or by heat treatment.

[0073] The layers can be removed individually, in groups, or all together simultaneously. Preferably, all layers and non-crosslinked regions of (B) are removed in a single step. Depending on the nature of the layers, this can be achieved by treating them with a solvent-based or water-based washout medium (e.g., organic solvents, mixtures thereof, water, aqueous solutions, or water-organic solvent mixtures, etc., that can dissolve, emulsify, and / or disperse the non-crosslinked regions in layer (B)).

[0074] In another embodiment, the removal of non-crosslinked areas of layer (C), and layer (E) if present, and layer (B) in step (v) is carried out thermally, in other words, by introducing heat to soften or partially liquefy the material in the layer. Heating of the exposed relief precursor can be carried out by all techniques known to those skilled in the art, e.g., irradiation with IR light, action of a hot gas (e.g., air), use of a hot roller, or any desired combination thereof. To remove (visually) liquid areas, all techniques and processes well known to those skilled in the art can be used, e.g., blowing, suction, beating, blasting (with particles and / or droplets), stripping, wiping, transfer to a developer, and any desired combination thereof. Preferably, the liquid material is taken up (absorbed and / or adsorbed) by a developer that is in continuous contact with the heated surface of the relief precursor. This procedure is repeated until the desired relief height is reached. Available developers are paper, woven and nonwoven fabrics, and films that can take up liquefied material and may consist of natural fibers and / or polymer fibers. It is preferable to use polymer nonwovens or nonwoven fiber webs such as cellulose, cotton, polyester, polyamide, polyurethane, and any desired combination thereof, which are stable at the temperature used during development.

[0075] An object of the present invention is also a method for manufacturing an optimized relief structure, the method being performed multiple times in steps (i) to (viii), thereby, in step (vii), the re-exposure to UVA and / or UVC light is varied with respect to the dose and / or time-series sequence of the UVA and UVC re-exposure steps in order to optimize the surface properties of the relief.

[0076] The object of the present invention is also a relief structure that can be obtained according to the above method and its use. The relief structure can be used as a pad printing plate, flexographic plate, letterpress plate, gravure plate, microfluidic component, microreactor, forelectic cell, photonic crystal, or optical component. In the case of a microfluidic component or microreactor, when using a nonpolar fluid, it may be advantageous to make the surface hydrophobic to use an aqueous or highly polar fluid to reduce interaction with the wall or to create a hydrophilic surface. In the case of a forelectic cell, photonic crystal, or optical component, making the surface hydrophobic or hydrophilic, respectively, may be advantageous in terms of contamination and cleaning.

[0077] The present invention will be explained in more detail by the following embodiments. [Examples]

[0078] method: Inflow Evaluation To evaluate ink inflow, plates were assessed after approximately 1,000 linear meters of printing by evaluating the color value field from 10% to 50%. Significant inflow (large amount of ink in the gaps) was classified as "-", moderate inflow as "0", and little to no inflow (no ink in the gaps) as "+".

[0079] Gloss measurement method Gloss measurements were performed to provide evidence of mobile surface-active additives (MSAs) on the plate surface. Gloss was measured at a viewing angle of 60° using a micro-TRI-gloss μ gloss meter (BYK-Gardner GmbH). The gloss meter was calibrated before measurement using an integrated calibration standard. The results are the average of three measurements at each different point on the plate surface. Removing the MSA by cleaning the surface with a solvent increased the gloss to 40-50 GU.

[0080] Figures 1-3 show the change in gloss units (GU) as a function of various re-exposure times in days.

[0081] IR measurement method FT-IR measurements were performed to provide evidence of MSA on the plate surface. A Tensor27 FT-IR (Bruker) with a PIKE MIRacle Diamant / ZnSe ATR-IR unit (PIKE Technologies) was used for the FT-IR measurements of the plate surface. Data were captured and analyzed using Opus software version 7.5 (Bruker). Spectral background correction was performed automatically. 719 and 729 cm⁻¹ were used as measures of MSA presence. -1 The integral of the IR band was used. For that purpose, they were 1730 cm². -1 The integral was standardized to the IR band, and zero values ​​(results without MSA) were subtracted. Signals attributable to MSA were determined by IR spectroscopy of the pure substance. After washing the surface with a solvent to remove MSA, signals attributable to MSA in the IR spectrum were no longer visible.

[0082] Figures 4-6 show 719 and 729 cm after 7 days at a predetermined re-exposure time. -1 The integral of the IR band is shown.

[0083] Contact angle measurement method The effect of MSA on surface wetting by water was investigated by contact angle measurement. For this purpose, 10 μL of demineralized water was dropped onto the surface of a printing plate. The droplet profiles were captured using a Keyence VHX-500F optical microscope with a VH-Z20R lens and VH-S30 tripod. The droplet radius r and height h were measured from these captures using relevant software. The contact angle θ was calculated using trigonometry (Equation 1). θ = arccos(1 - h / r) (1)

[0084] Example 1: An SBS-based relief precursor (total thickness 1.14 mm) was prepared on a polyester carrier containing 1 wt% paraffin wax (>C20) with a melting point of 50-57°C as MSA, and 2 wt% benzyl-α,α-dimethylacetal (IGM Resins BV). The relief precursor was exposed at 16 mW / cm² using a nyloflex® Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL80W / 10-R). 2 The sample was exposed from the back side for 25 seconds at this intensity. After removing the protective film, the precursor was imaged with ThermoFlexX20 (Xeikon), followed by exposure at 16 mW / cm² at 40°C in a nyloflex® Combi FIII exposure unit (Flint Group) using a fluorescent tube (Philips TL80W / 10-R). 2 The sample was exposed to UVA (Philips TL60W / 10-R, intensity 11mW / cm²) through the mask layer for 15 minutes. The exposed precursor was washed with a nylonflex® Digital Washer FIII (Flint Group) at a rate of 220 mm / min using nylonolv A. Drying was performed at 60°C for 120 minutes. Next, various re-exposures were performed with a nylonflex® Combi FIII exposure unit, thereby obtaining samples with no UVA (Philips TL60W / 10-R, intensity 11mW / cm²). 2 ) only, UVC (Philips TUV 75WHOG75T8, intensity 13mW / cm 2 Only UVA and UVC exposures were used, and continuous and simultaneous exposures were performed, with each case at 40°C. In this context, simultaneous means that both exposures (using UVA and UVC) were started at the same time. Next, IR and gloss measurements of the thus formed printed surface were performed at time intervals. MSA was not included for reference. 1A means a 1 minute re-exposure to UVA light, and 1C means a 1 minute re-exposure to UVC light.

[0085] Figures 1, 2, and 3 show the progression of gloss on the printing plate surface over time under various re-exposure conditions. As MSA diffuses to the surface, the gloss value decreases. Compared with Figures 4, 5, and 6, it can be seen that the decrease in gloss value is related to an increase in the IR signal. In a 3-minute re-exposure to UVC (Figure 1), the clear effect of the UVA re-exposure time on MSA migration is not yet apparent. In a 10-minute re-exposure to UVC (Figure 2), the amount of MSA decreases rapidly as the re-exposure time increases. The effect of UVC re-exposure on MSA migration is most strongly felt when combined with a 10-minute re-exposure to UVA. In the case of a 10-minute UVA exposure and a 10-minute re-exposure to UVC, far less MSA reaches the printing surface than in the case of a 10-minute re-exposure to UVA without UVC exposure (Figure 3). Therefore, the properties of the printing surface can be controlled.

[0086] [Table 1]

[0087] Table 1 shows the IR integral and gloss of the printed surface after 2 days as a function of re-exposure conditions. A higher IR integral value indicates more MSA on the plate surface. The IR integral correlates with the reciprocal of gloss. Low gloss is evidence of the presence of MSA on the surface. If MSA is absent, it cannot be detected by IR spectroscopy. With 10 minutes of exposure to UVA followed by 10 minutes of re-exposure to UVC, far less MSA reaches the printed surface than with no re-exposure or 10 minutes of re-exposure to UVA without UVC exposure. Therefore, the characteristics of the printed surface can be controlled.

[0088] [Table 2]

[0089] Table 2 shows the effects of UVA and UVC exposure on the presence of MSA on the plate surface. A 7-day period was chosen to ensure that MSA does not actually reach the surface. Reference 1 shows the values ​​that occur without MSA. The less UVA and UVC light applied to the printing plate using MSA, the more MSA is present on the surface after 7 days. The effect of UVC light here is greater than that of UVA light. The values ​​obtained with combinations of UVA and UVC re-exposure correspond to the values ​​for printing plates without MSA.

[0090] Example 2: a) SIS-based relief precursors (1.14 mm thick) were prepared on a polyester carrier containing 1% by weight of paraffin wax (>C35) with a melting point of 58°C, 5% by weight of benzyl-α,α-dimethylacetal (IGM Resins BV), and 0.5% by weight of 1-hydroxycyclohexyl phenyl ketone (IGM Resins BV) as MSA. b) A second relief precursor, which does not contain 1-hydroxycyclohexylphenyl ketone, was prepared in the same manner as in a).

[0091] Both plate types use a fluorescent tube (Philips TL80W / 10-R) with a nyloflex® Combi FIII exposure unit (Flint Group) at 16 mW / cm². 2 The sample was exposed from the back side for 15 seconds (a) and 10 seconds (b) at the specified intensity. After removing the protective film, the precursor was imaged with ThermoFlexX20 (Xeikon), followed by exposure at 16 mW / cm² at 40°C using a nyloflex® Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL80W / 10-R). 2The sample was exposed to light through a mask layer for 15 minutes at an intensity of 11 mW / cm². The precursor was washed with nylonolv A at a rate of 200 mm / min using a nylonflex® Digital Washer FIII (Flint Group). Drying was performed at 60°C for 120 minutes. Next, various re-exposures were performed at 40°C using a nylonflex® Combi FIII exposure unit. This involved the parallel and simultaneous use of UVA and UVC exposures. In the former case, the intensity was 11 mW / cm². 2 UVA exposure (Philips TL60W / 10-R) for 10 minutes at an intensity of 13 mW / cm². 2 In the first case, UVC exposure (Philips TUV75W HOG75T8) was performed for 3 minutes. In the second case, there was 10 minutes of UVA exposure followed by 10 minutes of UVC exposure. Next, gloss measurements were performed at time intervals on the unprinted area (floor) thus formed.

[0092] [Table 3]

[0093] Table 3 shows the gloss of the printing plate surface after 3 days and the inflow of ink into the printing plate after printing with solvent-based ink (LM). Lower gloss values ​​were observed with 10 minutes of UVA and 10 minutes of UVC re-exposure compared to no re-exposure (Example 2a) or 10 minutes of UVA and 3 minutes of UVC re-exposure (Example 2b) (Example 2c). This indicates the presence of MSA on the floor surface. In printing tests, the printing plates from Examples 2a and 2b showed reduced inflow.

[0094] Example 3: a. An SBS-based relief precursor (1.14 mm thick) was fabricated on a polyester carrier containing 1 wt% paraffin wax (>C35) with a melting point of 58°C as MSA and 2 wt% benzyl-α,α-dimethylacetal (IGM Resins BV). This was exposed at 19 mW / cm² using a fluorescent tube (Light Emission Tech F100T12 / 10-R100W) in a Next FV exposure unit (Flint Group). 2 The sample was exposed from the back side for 26 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 19 mW / cm² using a fluorescent tube (Light Emission Tech F100T12 / 10-R100W) in a Next FV exposure unit (Flint Group). 2 The sample was exposed to a mask layer for 10 minutes at the specified intensity. The precursor was developed at a rate of 255 mm / min using nylonolv A (Flint Group) with nylonflex® Flowline Washer FV (Flint Group). Drying was performed at 60°C for 120 minutes. Next, UVA exposure was performed (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. The UVA exposure time was 10 minutes, and the UVC exposure time was increased from 0 to 10 minutes at 2-minute intervals. b. An SBS-based relief precursor (1.14 mm thick) was fabricated on a polyester carrier containing 1 wt% paraffin wax (>C35) with a melting point of 58°C as MSA and 5 wt% benzyl-α,α-dimethylacetal (IGM Resins BV). This was exposed at 19 mW / cm² using a fluorescent tube (Light Emission Tech F100T12 / 10-R100W) in a Next FV exposure unit (Flint Group). 2The sample was exposed from the back side for 14 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 19 mW / cm² using a fluorescent tube (Light Emission Tech F100T12 / 10-R100W) with a Next FV exposure unit (Flint Group). 2 The sample was exposed to UVA light for 8 minutes through a mask layer at the specified intensity. The precursor was developed at a rate of 285 mm / min using nylonolv A (Flint Group) with nylonflex® Flowline Washer FV (Flint Group). Drying was performed at 60°C for 120 minutes. Next, UVA exposure was performed (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. The UVA exposure time was 8 minutes, and the UVC exposure time was increased from 0 to 10 minutes at 2-minute intervals. c. An SBS-based relief precursor (1.14 mm thick) was fabricated on a polyester carrier containing 1 wt% paraffin wax (>C35) with a melting point of 58°C as MSA and 5 wt% benzyl-α,α-dimethylacetal (IGM Resins BV). This was exposed at 19 mW / cm² using a fluorescent tube (Light Emission Tech F100T12 / 10-R100W) in a Next FV exposure unit (Flint Group). 2 The sample was exposed from the back side for 26 seconds at this intensity. After removing the protective film, the precursor was imaged with CDI2530 (Esko), followed by exposure at 3 × 250 mm / min and 800 mW / cm². 2The sample was exposed through a mask layer using a UV LED strip of intensity 12 mW / cm² in a Next FV exposure unit (Flint Group). The precursor was developed at a speed of 255 mm / min using nylonolv A (Flint Group) in a nylonflex® Flowline Washer FV (Flint Group). Drying was performed at 60°C for 120 minutes. Next, UVA exposure (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²) was performed. 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. The UVA exposure time was 8 minutes, and the UVC exposure time was increased from 0 to 10 minutes at 2-minute intervals.

[0095] Print parameters: The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a 400mm wide, 55μm thick LD-PE film (Delo) that had been pre-treated on one side with corona, using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). The printing plate was secured using Lohmann 5.3 foam adhesive tape (Lohmann). The anilox roller used had a screen resolution of 420 lines / cm and a 3.5cm width. 3 / m 2 It was supplied in the specified volume. The printing speed was 200 m / min, and the horizontal paper feed was 70 μm at the printing unit and 60 μm at the screen roller. Drying was performed in two stages at 40°C and 60°C.

[0096] [Table 4]

[0097] Table 4 shows the evaluation of inflow into the printing plate after printing with solvent-based inks at various ratios of simultaneous UVA and UVC re-exposure. The higher the applied UVC re-exposure dose, i.e., the smaller the ratio of UVA to UVC re-exposure doses, the greater the inflow into the interstitial space of the printing plate. On the other hand, at moderate UVC re-exposure doses, inflow into the interstitial space is largely avoided by the movement of MSA.

[0098] Example 4: MSA's relocation A SIS-based relief precursor (1.14 mm thick) was fabricated on a polyester carrier containing 1 wt% paraffin wax (>C35) with a melting point of 58°C as MSA and 5 wt% benzyl-α,α-dimethylacetal (IGM Resins BV). This was exposed at 28 mW / cm² using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). 2 The sample was exposed from the back side for 14 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 19 mW / cm² using a fluorescent tube (Light Emission Tech F100T12 / 10-R100W) with a Next FV exposure unit (Flint Group). 2 The sample was exposed to a mask layer for 8 minutes at the specified intensity. The precursor was developed at a rate of 290 mm / min using nylonolv A (Flint Group) with nylonflex® Flowline Washer FV (Flint Group). Drying was performed at 60°C for 120 minutes. Next, UVA exposure was performed (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. UVA exposure time was 8 minutes, and UVC exposure time was 0 and 2 minutes.

[0099] UV-curing ink printing parameters: Printing with Flexocure Force UV-curing ink (Flint Group) was performed using an MO4 press (Nilpeter) equipped with an FA4 flexographic unit. The printing media used were either 330mm wide, 130μm thick PE-based adhesive label material (Raflatac) or 330mm wide, 120μm thick paper-based adhesive label material (Raflacoat, UPM). The printing plate was secured using medium-hardness Tesa Blue foam adhesive tape (Tesa). The anilox roller used had a screen resolution of 500 lines / cm and a 2.5cm width. 3 / m 2 It was provided in this volume. The printing speed was 100 m / min.

[0100] [Table 5]

[0101] Table 5 shows the effect of MSA when printing on PE film or paper using UV-curing ink. UVC re-exposure reduces the amount of MSA that diffuses onto the surface of the printing plate. When printing on PE film, the absence of MSA reduces full-tone color density; when printing on paper, leading edges appear. Without UVC re-exposure, MSA diffuses onto the surface of the printing plate and promotes ink transfer to the associated printing medium. When printing on PE film, the presence of MSA increases the observed full-tone color density; when printing on paper, leading edges disappear.

[0102] Example 5: An SBS-based relief precursor (1.14 mm thick) was fabricated on a polyester carrier containing 0.1 or 2.5 wt% paraffin wax (>C35) with a melting point of 58°C as MSA and 5 wt% benzyl-α,α-dimethylacetal (IGM Resins BV). This was exposed at 28 mW / cm² using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). 2The sample was exposed from the back side for 17 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 28 mW / cm² using a Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL60W / 10-R). 2 The sample was exposed to a mask layer at an intensity of 12 mW / cm² for 8 minutes. The precursor was developed at a rate of 250 mm / min using nyloflex® Flowline Washer FV (Flint Group) and Cyrel® Flexosol-i (DuPont) as the washout medium. Drying was performed at 60°C for 120 minutes. Next, UVA exposure was performed (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. The UVA exposure time was 8 minutes, and the UVC exposure time was 2 minutes.

[0103] Printing conditions: The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a 400mm wide, 55μm thick LD-PE film (Delo) that had been pre-treated on one side with corona, using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). The printing plate was secured using Lohmann 5.3 foam adhesive tape (Lohmann). The anilox roller used had a screen resolution of 420 lines / cm and a 3.5cm width. 3 / m 2 It was provided in this volume. The printing speed was 200 m / min.

[0104] [Table 6]

[0105] In reference 5a, significant plate inflow was observed. Adding MSA significantly reduced the inflow (Examples 5b and 5c (Table 6)).

[0106] Example 6: SBS-based relief precursors (1.14 mm thick) were prepared on a polyester carrier containing 1% by weight of paraffin wax (>C35) with a melting point of 58°C as the MSA, 5% by weight of benzyl-α,α-dimethylacetal (IGM Resins BV), and 0%, 0.25%, or 0.5% of 1-hydroxycyclohexyl phenyl ketone (C1), or a mixture of 0.5% of 2-[2-oxo-2-phenylacetoxyethoxy]ethyl oxyphenyl acetate and 2-[2-hydroxyethoxy]ethyl oxyphenyl acetate (C2) (each IGM Resins BV). This was exposed at 28 mW / cm² using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). 2 The sample was exposed from the back side for 22 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 28 mW / cm² using a Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL60W / 10-R). 2 The sample was exposed to a mask layer at an intensity of 10 minutes. The precursor was developed at a rate of 250 mm / min using nyloflex® Flowline Washer FV (Flint Group) and Cyrel® Flexosol-i (DuPont) as the washout medium. Drying was performed at 60°C for 120 minutes. Next, UVA exposure (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²) was performed. 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. The UVA exposure time was 8 minutes, and the UVC exposure time was 2 minutes.

[0107] Printing conditions: The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a 400mm wide, 55μm thick LD-PE film (Delo) that had been pre-treated on one side with corona, using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). The printing plate was secured using Lohmann 5.3 foam adhesive tape (Lohmann). The anilox roller used had a screen resolution of 420 lines / cm and a 3.5cm width. 3 / m 2 It was provided in this volume. The printing speed was 200 m / min.

[0108] [Table 7]

[0109] In the absence of MSA or UVC photoinitiator (reference 6a), significant plate inflow is observed. Adding MSA and UVC photoinitiator significantly reduces inflow. In this plate formulation, the addition of 0.5% UVC photoinitiator C2 further reduces inflow (Table 7).

[0110] Example 7: SIS-based relief precursors (1.14 mm thick) were fabricated on a polyester carrier containing 1 wt% paraffin wax (>C35) with a melting point of 58°C as the MSA, 5 wt% benzyl-α,α-dimethylacetal (IGM Resins BV), and 0%, 0.25%, or 0.5% 1-hydroxycyclohexyl phenyl ketone (C1) (IGM Resins BV). This was exposed at 28 mW / cm² using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). 2The sample was exposed from the back side for 14 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 28 mW / cm² using a Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL60W / 10-R). 2 The sample was exposed to a mask layer at an intensity of 12 mW / cm² for 8 minutes. The precursor was developed at a rate of 150 mm / min using nyloflex® Flowline Washer FV (Flint Group) and Cyrel® Flexosol-i (DuPont) as the washout medium. Drying was performed at 60°C for 120 minutes. Next, UVA exposure was performed (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. The UVA exposure time was 8 minutes, and the UVC exposure time was 2 minutes.

[0111] Printing conditions: The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a 400mm wide, 55μm thick LD-PE film (Delo) that had been pre-treated on one side with corona, using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). The printing plate was secured using Lohmann 5.3 foam adhesive tape (Lohmann). The anilox roller used had a screen resolution of 420 lines / cm and a 3.5cm width. 3 / m 2 It was provided in this volume. The printing speed was 200 m / min.

[0112] [Table 8]

[0113] Inflow is reduced by increasing the UVC photoinitiator content while keeping the UVA photoinitiator content the same. When using 0.5% UVC photoinitiator (Example 7c), almost no inflow is observed (Table 8).

[0114] Example 8: SIS-based relief precursors (1.70 mm thick) were prepared on a polyester carrier containing 1 wt% paraffin wax (>C35) with a melting point of 58°C, 5 wt% benzyl-α,α-dimethylacetal (IGM Resins BV), and 0%, 0.25%, or 0.5% 1-hydroxycyclohexyl phenyl ketone (C1) (IGM Resins BV). This was exposed at 28 mW / cm² using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). 2 The sample was exposed from the back side for 40 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 28 mW / cm² using a Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL60W / 10-R). 2 The sample was exposed to UVA light for 8 minutes through a mask layer at the specified intensity. The precursor was developed at a rate of 230 mm / min using nylonflex® Flowline Washer FV (Flint Group) as the washout medium and nylonolv A (Flint Group). Drying was performed at 60°C for 120 minutes. Next, UVA exposure was performed (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²). 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 The exposures were started simultaneously using ( ), run in parallel, and re-exposed at room temperature. The UVA exposure time was 8 minutes, and the UVC exposure time was 4 minutes.

[0115] Printing conditions: The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a 400mm wide, 55μm thick LD-PE film (Delo) that had been pre-treated on one side with corona, using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). The printing plate was secured using Lohmann 5.3 foam adhesive tape (Lohmann). The anilox roller used had a screen resolution of 420 lines / cm and a 3.5cm width. 3 / m 2 It was provided in this volume. The printing speed was 200 m / min.

[0116] [Table 9]

[0117] Compared to reference 8a, plate inflow decreased sharply with the addition of MSA and photoinitiator C1 (Examples 8b and 8c). Further increasing the UVC photoinitiator content from 0.5% (Example 8b) to 1% (Example 8c) did not result in any further improvement in inflow (Table 9).

[0118] Example 9: SIS-based relief precursors (1.70 mm thick) were fabricated on a polyester carrier containing 1% by weight of paraffin wax (>C35) with a melting point of 58°C, 1% by weight of benzyl-α,α-dimethylacetal (IGM Resins BV), and 0%, 0.5%, 1.0%, 1.5%, or 2.0% of 1-(4-methylphenyl)-1-dodecanone (C3) (BASF). This was exposed at 28 mW / cm² using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). 2 The sample was exposed from the back side for 40 seconds at this intensity. After removing the protective film, the precursor was imaged with a CDI2530 (Esko), followed by exposure at 28 mW / cm² using a Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL60W / 10-R). 2The sample was exposed to UVA light for 9 minutes through a vacuum-fixed, mounted mask layer. After removing the mask layer, the precursor was developed at a rate of 250 mm / min using a nylonflex® Flowline Washer FV (Flint Group) with Cyrel® Flexosol-i (DuPont) as the washout medium. Drying was performed at 60°C for 120 minutes. Next, UVA exposure (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm²) was performed. 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11mW / cm²) 2 Simultaneous exposures were started and run in parallel using ( ), followed by re-exposure at room temperature. The UVA exposure time was 10 minutes, and the UVC exposure time was 5 minutes.

[0119] Printing conditions: The solvent-based ink Flexistar MV Process Cyan (Flint Group) was printed on a 400mm wide, 55μm thick LD-PE film (Delo) that had been pre-treated on one side with corona, using an F&K Flexpress 6S / 8 printing press (Fischer & Krecke). The printing plate was secured using Lohmann 5.3 foam adhesive tape (Lohmann). The anilox roller used had a screen resolution of 420 lines / cm and a 3.5cm width. 3 / m 2 It was provided in this volume. The printing speed was 200 m / min.

[0120] [Table 10]

[0121] In reference 9a, significant plate inflow was observed. Adding MSA and photoinitiator C3 (Examples 9b-9e) significantly reduced inflow. At a concentration of 1.0% UVC photoinitiator C3 (Example 9c), almost no inflow was observed. The same was true when the UVC photoinitiator concentration was further increased to 1.5% or 2.0% (Examples 9d and 9e) (Table 10).

[0122] Example 10: SIS-based relief precursors (total thickness 1.14 mm) were prepared on a polyester carrier containing 1 wt% paraffin wax (>C20) with a melting point of 50-57°C, 2 wt% benzyl-α,α-dimethylacetal (IGM Resins BV), and 0% or 0.5% 1-hydroxycyclohexyl phenyl ketone (IGM Resins BV) as MSA. The relief precursors were exposed at 16 mW / cm² using a nyloflex® Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL80W / 10-R). 2 The sample was exposed from the back side for 10 seconds at this intensity. After removing the protective film, the precursor was imaged with ThermoFlexX20 (Xeikon), followed by exposure at 16 mW / cm² using a nyloflex® Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL80W / 10-R). 2 The material was exposed to UVA (Philips TL60W / 10-R, intensity 11 mW / cm²) through a mask layer for 15 minutes at 40°C. The exposed precursor was washed with a nylonflex® Digital Washer FIII (Flint Group) at a rate of 200 mm / min using nylonolv A. Drying was performed at 60°C for 120 minutes. Next, various re-exposures were performed with a nylonflex® Combi FIII exposure unit, thereby obtaining UVA (Philips TL60W / 10-R, intensity 11 mW / cm²). 2 ) only, UVC (Philips TUV 75W HO G75T8, intensity 13mW / cm²) 2Either UVA or UVC exposure was used, each at 40°C. In this context, "simultaneous" means that both exposures (UVA and UVC) were started at the same time. After developing the printing plates and storing them for at least one week, contact angle measurements were performed on the printing surfaces thus formed. The reference used was a surface of pure MSA obtained by melting and subsequent cooling.

[0123] The contact angle is a measure of surface wetting. Uniformly wetting a surface with a liquid (printing ink) is a fundamental prerequisite for a successful printing process. If the surface is not completely wetted, the print form cannot be fully transferred to the printing medium. Wetting is critically 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, the liquid droplets on the surface will exhibit a large contact angle. A small difference results in uniform wetting of the surface with the liquid and a small contact angle. MSA (Multilayer Surface Aquifer) creates a hydrophobic surface. For example, polar liquids such as water are expected to exhibit a large contact angle.

[0124] Table 11 shows the contact angles of water droplets on the printing plate with and without MSA on the plate surface. The presence of MSA is controlled by re-exposure. Pure MSA serves as a reference.

[0125] [Table 11]

[0126] The presence of MSA on a surface affects the wetting of the surface by water. When MSA is present on the surface of a printing plate, the contact angle of a water droplet is much larger than when MSA is absent. When MSA is present on the plate surface (e.g., 10b, 10d, and 10f), the contact angle of a water droplet approaches that of pure MSA (see 10a). When MSA is absent, the concentration of the photoinitiator particularly affects the contact angle. Using 1% UVC PI (e.g., 10e) resulted in a smaller contact angle than not using it (e.g., 10c). When printing with water-based inks, the presence of MSA can consequently cause wetting problems. MSA migration can be controlled by re-exposure.

[0127] Example 11: The SBS-based relief precursor (total thickness 1.14 mm) was prepared on a polyester carrier containing 1 wt% paraffin wax (>C20) with a melting point of 50-57°C as MSA, and 5 wt% benzyl-α,α-dimethylacetal (IGM Resins BV). The relief precursor was exposed at 16 mW / cm² using a nyloflex® Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL80W / 10-R). 2 The sample was exposed from the back side at this intensity for 18 seconds. After removing the protective film, the precursor was imaged with ThermoFlexX20 (Xeikon), followed by exposure at 16 mW / cm² using a nyloflex® Combi FIII exposure unit (Flint Group) with a fluorescent tube (Philips TL80W / 10-R). 2 The surface was exposed to UVA light (Philips TL60W / 10-R, intensity 11 mW / cm²) through the mask layer for 15 minutes at 40°C. The exposed precursor was washed with a nylonflex® Digital Washer FIII (Flint Group) using nylonolv A at a rate of 220 mm / min. Drying was performed at 60°C for 120 minutes. Next, the printing plate was exposed to UVA light (Philips TL60W / 10-R, intensity 11 mW / cm²) in a nylonflex® Combi FIII exposure unit. 2) for 10 minutes, and then re-exposed to UVC light (Philips TUV 75W HO G75T8, intensity 13 mW / cm 2 ) for 5 minutes. Both exposures (UVA and UVC) were started simultaneously and carried out at 40 °C. After storage for at least one week after development of the printing plate, contact angle measurements were performed on the printed surface thus formed. The reference used was the surface of pure MSA obtained by melting and subsequent cooling.

[0128]

Table 12

[0129] When MSA is present on the surface of the printing plate (Example 11b), the contact angle approaches the contact angle of pure MSA (Reference 11a). When there is no MSA on the surface of the plate (Example 11c), even if other processing conditions are the same, a much smaller contact angle is obtained.

[0130] Example 12: The SBS-based relief precursor (thickness 1.14 mm) was manufactured on a polyester carrier containing 1 wt% paraffin wax (>C35) with a melting point of 58 °C and 2 wt% benzyl-α,α-dimethylacetal (IGM Resins B.V.) as MSA. The plate either did not contain MSA, contained 1 wt% paraffin wax (>C35) with a melting point of 58 °C, or contained 0.5 wt% polysiloxane polyester acrylate (PPA) as MSA. The relief precursor was exposed from the back surface for 20 seconds at an intensity of 26 mW / cm using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). After peeling off the protective film, the precursor was imaged with CDI2530 (Esko), and then exposed at an intensity of 26 mW / cm using a fluorescent tube (Philips TL60W / 10-R) in a Combi FIII exposure unit (Flint Group). 2 of intensity. 2Exposed through the mask layer for 10 minutes at the intensity of 2 . The precursor was developed at a speed of 255 mm / min using nylosolv A (Flint Group) with a nyloflex® Flowline Washer FV (Flint Group). Drying was carried out at 60 °C for 120 minutes. Next, UVA exposure (Philips TL80W / 10-R SLV G13, intensity 12 mW / cm 2 ) and UVC exposure (Philips TUV TL-D95W HO SLV / 25, intensity 11 mW / cm

[0131] Printing conditions: ) were started simultaneously and carried out in parallel for re-exposure at room temperature. The UVA exposure time was 10 minutes and the UVC exposure time was 6 minutes. 3 / m 2 . For printing using Flexocure Ancora Process Cyan UV curing ink (Flint Group), an MO4 printing press (Nilpeter) equipped with an FA4 flexo unit was used. The printing media used were single-sided corona-treated PE-based adhesive label materials (Raflatac) or paper-based adhesive label materials (Raflacoat, UPM) with a thickness of 120 μm. A medium-hardness Tesa blue foam adhesive tape (Tesa) was used to fix the printing plate. The anilox roller used was provided with a screen resolution of 500 lines / cm and a volume of 2.5 cm

[0132] result: Table 13: Plate run-in after printing on PE film and paper. Re-exposure used: intensity UVA 7200 mJ / cm 2 ; UVC = 3960 mJ / cm 2 . Ratio of UVA / UVC re-exposure intensity = 1.8.

[0133]

Table 13

[0134] Table 13 shows the effect of MSA on plate inflow when printing with UV-curing inks. Significant inflow is observed without MSA. Adding paraffin wax as MSA can significantly reduce block inflow. Further improvement in inflow is observed when polysiloxane polyester acrylate is used as MSA.

Claims

1. Photopolymerizable relief precursors including the following: (A) Dimensionally stable carrier, (B) A photopolymerizable relief-forming layer comprising at least a crosslinkable elastomer binder, an ethylenically unsaturated monomer, a mobile surfactant, a UVA-activated photoinitiator, and a UVC-activated photoinitiator.

2. The photopolymerizable relief precursor according to claim 1, characterized in that the movable surface-active additive is selected from the group consisting of ionic or nonionic surfactants, long-chain hydrocarbons, waxes, particularly paraffin waxes, organosilicon compounds, particularly silicone oils, silanes and siloxanes, or mixtures thereof.

3. The photopolymerizable relief precursor according to claim 1 or 2, characterized in that the movable surface-active additive is paraffin wax.

4. The photopolymerizable relief precursor according to claim 1 or 2, characterized in that the movable surface-active additive is a polysiloxane polyester acrylate.

5. The photopolymerizable relief precursor according to any one of claims 1 to 4, characterized in that the photoinitiator activatable by UVA light is selected from the group consisting of benzyl ketal, acylphosphine oxide, bisacylphosphine oxide, aminophenyl ketone, phenyloxime ester, and mixtures thereof.

6. The photopolymerizable relief precursor according to any one of claims 1 to 5, characterized in that the photoinitiator activatable by UVC light is selected from the group consisting of hydroxyphenyl ketone, benzoyl formate, benzophenone, arylalkyl ketone, arylbenzyl ketone, and mixtures thereof.

7. The photopolymerizable relief precursor according to claim 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, benzyldimethyl ketal, and benzyldiethyl ketal, and the photoinitiator activatable with UVC light is selected from the group consisting of 2-[2-oxo-2-phenylacetoxyethoxy]ethyl oxyphenyl acetate, 2-[2-hydroxyethoxy]ethyl oxyphenyl acetate, methylbenzoyl formate, p-tolyluundecylketone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one and mixtures thereof.

8. The photopolymerizable relief precursor according to any one of claims 1 to 7, characterized in that the photopolymerizable relief-forming layer contains the movable 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.

9. The photopolymerizable relief precursor according to any one of claims 1 to 8, characterized in that the photopolymerizable relief-forming layer contains, based on the weight of the photopolymerizable relief-forming layer, a photoinitiator that can be activated by UVA light 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.

10. The photopolymerizable relief precursor according to any one of claims 1 to 9, characterized in that the photopolymerizable relief-forming layer contains a photoinitiator activatable by UVC light 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 weight of the photopolymerizable relief-forming layer.

11. The photopolymerizable relief precursor according to any one of claims 1 to 10, characterized in that the mass ratio of the UVA-activated photoinitiator to the UVC-activated photoinitiator is 0.1 to 50, preferably 0.5 to 40, more preferably 0.5 to 30, and very preferably 0.5 to 15.

12. Manufacturing method for relief structures, including the following steps: (i) Providing a photopolymerizable relief precursor comprising at least one movable surface-active additive, (ii) Application of a mask onto the photopolymerizable relief forming layer, or generation of a structured mask layer, (iii) Optionally, exposure of the back surface to electromagnetic radiation via the carrier layer. (iv-a) Exposure of the photopolymerizable relief-forming layer to electromagnetic radiation through the mask or the mask layer, (v) Removal of the mask or the mask layer, any further layers, and the non-photopolymerized regions of the relief-forming layer that were not exposed in step (iv), thereby generating a relief. (vi) Optional: drying of the relief, (vii) Re-exposure of the relief from the side opposite to the carrier layer to UVA light in the wavelength range of 315–380 nm and / or UVC light in the wavelength range of 200–280 nm, thereby re-crosslinking the relief to adjust the surface properties of the relief and adjust the permeability of the movable surface active additive. (viiii) Optional, further processing steps.

13. Manufacturing method for relief structures, including the following steps: (i) Providing a photopolymerizable relief precursor comprising at least one movable surface-active additive, (iii) Optionally, exposure of the back surface to electromagnetic radiation via the carrier layer. (iv-b) Image exposure of the photopolymerizable relief-forming layer to electromagnetic radiation, (v) Further layers if present, and removal of non-photopolymerized regions of the relief-forming layer not exposed in step (iv), thus generating a relief. (vi) Optional: drying of the relief, (vii) Re-exposure of the relief from the side opposite to the carrier layer to UVA light in the wavelength range of 315–380 nm and / or UVC light in the wavelength range of 200–280 nm, thereby re-crosslinking the relief to adjust the surface properties of the relief and adjust the permeability of the movable surface active additive. (viiii) Optional, further processing steps.

14. The method according to claim 12 or 13, characterized in that step (vii) involves re-exposure to UVA and UVC light, thereby performing re-exposure to UVA and UVC light simultaneously, sequentially, or alternately.

15. The method according to claim 12 or 13, characterized in that the re-exposure conditions are adjusted as a function of the type of printing ink to adjust the surface properties of the relief for the printing ink.

16. The method according to claim 15, characterized in that the surface properties of the printing plate can be adjusted to be suitable for printing with solvent-based inks, water-based inks, or UV-curing inks by selecting re-exposure conditions.

17. A method according to any one of claims 12 to 16 for manufacturing an optimized relief structure, wherein the method is performed multiple times from step (i) to (viiii), characterized in that in step (vi), the re-exposure to UVA and / or UVC light is varied with respect to the dose and / or time-series sequence of the UVA and UVC re-exposure steps in order to optimize the surface properties of the relief.

18. The method according to any one of claims 12 to 17, characterized in that the movement of the at least one movable surface-active additive is controlled by the selection of exposure parameters in the re-exposure step.

19. The method according to any one of claims 12 to 18, characterized by re-exposure to UVA light at 100 to 30,000 mJ / cm², preferably 100 to 20,000 mJ / cm², more preferably 100 to 7,000 mJ / cm², and very preferably 500 to 7,000 mJ / cm².

20. The method according to any one of claims 12 to 19, characterized by re-exposure to UVC light at 100 to 20,000 mJ / cm², preferably 100 to 20,000 mJ / cm², more preferably 100 to 8,000 mJ / cm², and very preferably 500 to 8,000 mJ / cm².

21. The method according to any one of claims 12 to 20, characterized in that the ratio of UVA to UVC light doses (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.

22. The method according to any one of claims 12 to 15, characterized in that exposure to UVC light seals the surface of the layer due to its shallow penetration depth, and exposure to UVA light ensures stronger crosslinking of the entire layer.

23. A relief structure obtained using the method described in any one of claims 12 to 22.

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

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