Photosensitive components

Abstract

To achieve shortening of the production time of a relief structure, improvement of printing quality, predictability of a patternized surface, improvement in reliability and accuracy, improvement of durability of a relief structure and to achieve improvement of resolution of a printed image.SOLUTION: There is provided a photosensitive composition of a developable relief precursor which comprises at least one ethylenically unsaturated monomer as a component E, at least one photoinitiator or photoinitiator system as a component P, at least one water-soluble and / or water-dispersible binder as a component B and optionally one or a plurality of additives as a component A, wherein the component E contains at least one ionic group and the component E is present in an amount of 0.1 to 30 wt.% based on the total weight of the photosensitive composition.SELECTED DRAWING: None

Description

Detailed Description of the Invention

[0001] [Technical field] The field of the invention relates to developable relief precursor photosensitive compositions and the resulting relief structures used in flexographic, pad and letterpress printing.

[0002] [background] In the fields of pad printing, flexography, and letterpress printing, developable printing plates, also called relief precursors, are prepared and developed to create a relief structure with a desired patterned surface. The patterned surface is then covered with ink and pressed against a printing substrate. In this way, the ink can be transferred to the printing substrate, such as packaging, labels, paper rolls, polymer films, cardboard, and many other products, to create the desired image.

[0003] A relief precursor typically contains a photosensitive composition whose components crosslink or harden upon exposure to electromagnetic radiation. During exposure, the precursor is exposed to electromagnetic radiation in selected areas. It is in these areas that the photosensitive composition polymerizes, forms crosslinks, and hardens to create a relief profile that can be used for printing. This exposure is usually carried out conventionally or digitally. In conventional methods, the relief structure is created by placing a photographic mask on or over the relief precursor, followed by exposure through the photographic mask. The photographic mask has transparent areas that determine the selected areas of the precursor to be hardened. Electromagnetic radiation passes through the transparent areas and hardens the underlying photosensitive composition. In digital methods, the mask is created in situ directly on the relief precursor, for example, using a laser-ablatable mask layer in which motifs are created using a laser light source. In addition, other known methods, such as thermographic writing, can be used to create the hardened pattern.

[0004] After curing or polymerization and crosslinking, the exposed precursor is treated or washed using a suitable solvent or solvent mixture to dissolve the unexposed, uncured or unpolymerized areas of the relief-forming layer while retaining the exposed, polymerized and crosslinked areas, forming the relief of the printing plate. This treating or washing step is usually the most, if not the most, time-consuming step in the entire process of producing a relief structure.

[0005] Several developments and modifications have been made to relief precursors and their components in an attempt to address desired and more demanding printing needs, such as the ability to print on new, different, and more difficult printing substrates, printing at higher speeds, printing with better print quality, and thereby achieving sharper or brighter color images.

[0006] However, despite these developments, not only the relief precursor itself but also the method for producing said precursor and the method for manufacturing the resulting relief structures still need to be further improved, since some problems have not yet been solved and some additional aspects need to be improved.

[0007]

[0003] Existing relief precursors typically contain trace amounts of organic halogens, such as chlorine, bromine, and iodine, which are harmful chemicals that can have adverse effects on the environment when released from the precursor. When handling the relief precursor, said organic halogen components are transferred to the environment. Furthermore, development of the relief precursor is usually carried out with the aid of a developer solution, also known as a wash solution. During development, there is a risk that chemicals may be introduced into the developer solution and released into the environment when the liquid is disposed of.

[0008] Furthermore, when handling relief precursors before development, it is desirable to have precursors that are mechanically stable while still being sufficiently durable and flexible. Existing precursors often produce relief structures that exhibit undesirable characteristics after development. Such relief structures often exhibit poor mechanical quality and cracks and other deformations, especially after prolonged working or printing with the relief structures. In addition, the side edges of the relief precursors and relief structures tend to curl, which is quite troublesome and difficult to handle.

[0009] [Summary of the Invention] It is an object of the present invention to provide the art with an improved relief precursor, more particularly a photosensitive composition of a relief precursor, which at least partially solves or overcomes the above-mentioned problems and further improves additional aspects. In particular, the present invention aims to achieve a reduction in the production time of the relief structure, an improvement in the print quality, an increase in the predictability, reliability and precision of the patterned surface, and an improvement in the durability of the relief structure, and to achieve an improvement in the resolution of the printed image.

[0010] This object is achieved by the invention as set out in claim 1. The inventors have discovered that the object is achieved by means of a photosensitive composition of a developable relief precursor comprising at least one ethylenically unsaturated monomer as component E, at least one photoinitiator or photoinitiator system as component P, at least one water-soluble and / or water-dispersible binder as component B, and optionally one or more additives as component A.

[0011] Here, Component E contains at least one ionic group, and Component E is present in an amount of 0.5 to 30 wt % based on the total weight of the photosensitive composition.

[0012] The inclusion of an ionic group in the ethylenically unsaturated monomer increases the polarity of the photosensitive composition, imparting charge to the polymer chains and / or polymer networks formed by the ethylenically unsaturated monomer, along with the water-soluble and / or water-dispersible binder and optional additives. The formation of the polymer chains and / or networks containing the ethylenically unsaturated monomer is initiated by the photoinitiator or photoinitiator system present in the photosensitive composition according to the present invention, particularly upon exposure of the composition to electromagnetic radiation. The formation of these polymer chains and / or networks hardens and crosslinks the photosensitive composition, thereby creating the relief profile. The use of ethylenically unsaturated monomers with ionic groups as described herein reduces or avoids the release of harmful chemicals into the surroundings, e.g., the environment and the developer, particularly when the monomers are formed by esterification, in which acrylic acid is preferably used.

[0013] Furthermore, the time-consuming step of removing the unexposed areas is reduced.The photosensitive composition according to the present invention also increases the flexibility of the relief precursor and the relief structure, reducing the undesirable and troublesome "curl phenomenon".

[0014] With regard to Component E, the ethylenically unsaturated monomer is preferably present in an amount of 0.5 to 20 wt %, based on the total weight of the photosensitive composition. This wt % concentration has been found to provide the best results, as the concentration of Component E affects, among other things, the swelling ability, water solubility, and flexibility of the photosensitive composition, with higher concentrations tending to increase the water solubility of the photosensitive composition in both the unexposed and exposed regions. Water solubility should not be too high, as excessive water solubility in the cured photosensitive composition, especially in the exposed areas, can result in the cured photosensitive composition being washed away during development of the relief precursor. Additionally, higher concentrations can cause swelling of the relief structure to an undesirable extent. This can affect the accuracy of the relief structure and the reliability of printability, especially when printing with aqueous inks.

[0015] In a preferred embodiment, in order to achieve a reduction in washing time and thereby shorten the overall development process or manufacturing method of the relief structure, component E has a solubility in water of pH 7 at 20°C and 1 atmosphere of 200 g / l or more, preferably in the range of 200 to 1500 g / l, more preferably in the range of 500 to 1500 g / l.

[0016] In certain embodiments, component E preferably has a molecular weight in the range of 100 to 1000 g / mol, more preferably in the range of 110 to 500 g / mol, and even more preferably in the range of 120 to 300 g / mol. These ranges are preferred to aid in achieving desired properties, for example, to reduce cleaning times and allow for more rapid removal of unexposed areas of the relief precursor. Additionally, these ranges provide the resulting polymer chains and / or network with a desired degree of flexibility, which improves the properties of the relief precursor and the relief structure.

[0017] In one embodiment, component E comprises at least one of an acrylate group, a methacrylate group, an acrylamide group, a vinyl group, a vinyl ether group, or a combination thereof. These groups are particularly preferred because they provide optimal results with respect to polymerization and crosslinking of the photosensitive composition and exhibit reasonable compatibility with other components present in the photosensitive composition.

[0018] In one embodiment, component E has a vapor pressure of less than 50 hPa at 25° C. These vapor pressures should not be too high for environmental reasons and for reasons related to the ease, comfort and health of operators handling any one of the components, the photosensitive composition, the relief precursor and the relief structure.

[0019] In certain embodiments, component E has an AOX value of less than 2600 mg / L, preferably less than 1000 mg / L, and more preferably less than 100 mg / L. The AOX value is determined in accordance with the "DIN EN ISO 9562" standard and indicates the amount of adsorbable organic halides, hence the name AOX. By selecting the above range, the risk of migration of harmful chemicals into the surroundings, the developer, and the environment is reduced.

[0020] In certain embodiments, component E has an EOX value of less than 2000 mg / kg, preferably less than 200 mg / kg, and more preferably less than 50 mg / kg. The EOX value is determined according to the DIN 38414-17 standard using i-hexane as the solvent. This value indicates the extractable organic halogens, hence the name EOX. By selecting the above range, the risk of harmful chemicals being transferred to the surroundings, the developer, and the environment is reduced.

[0021] Preferably, the at least one ionic group contained in component E is selected from the group consisting of quaternary ammonium groups, carboxylate groups, sulfonate groups, sulfonium groups, phosphonium groups, and combinations thereof. These groups have been found to aid in achieving the desired effects described above and are preferred for their compatibility with other components in the photosensitive composition.

[0022] In one aspect of the invention, component E is a quaternized amino-functional monomer. Such monomers can act as cationic detergents and reduce undesirable phenomena such as sedimentation when washing the relief precursor during the development process.

[0023] In another aspect of the present invention, there is provided a photosensitive composition further comprising an ethylenically unsaturated compound as component EM, wherein said component EM does not have an ionic group. The presence of such a component in combination with other components in the photosensitive composition enhances the desired cleaning and mechanical durability properties of the relief precursor. Preferably, component EM is present in an amount of 0.5 to 50 wt %, preferably 0.9 to 40 wt %, more preferably 1 to 30 wt %, based on the total weight of the photosensitive composition, and the EM / E ratio is between 0.1 and 10, more preferably between 0.15 and 8, and even more preferably between 0.2 and 5. Such ratios have been found to achieve the aforementioned desired results in the cleaning and mechanical durability properties of the relief precursor.

[0024] With respect to component P, it is preferred to select said component P from the group including benzil ketals, hydroxyketones, aminoketones, acylphosphine oxides, bisacylphosphine oxides, thioxanthones, anthraquinones, coumarins, hexaarylbisimidazoles, benzophenones, and combinations thereof. These groups result in a suitable degree of radical formation and are suitable for low irradiation doses, preferably 16-20 Watts / cm, although even lower ranges may be possible. 2 This is preferable because it allows curing between 100°C and 150°C.

[0025] Additionally, component P may be a photoinitiator system further comprising a coinitiator, said coinitiator being selected from the group comprising amines, thiols, thioethers, aminoalcohols, thioetheramines, and combinations thereof.

[0026] Component B is a water-soluble and / or water-dispersible binder. Preferably, this binder is crosslinkable with component E, i.e., the polymer chain formed by the ethylenically unsaturated monomer and / or other additives. These binders can be linear, branched, star-shaped, or dendritic polymers, both of which can exist as homopolymers, statistical copolymers, block copolymers, or alternating copolymers. The mentioned polymers very often have functional groups that enhance solubility and / or can participate in crosslinking reactions. These groups include, for example, carboxy groups, SO groups, OH groups, thiol groups, ethylenically unsaturated (meth)acrylate groups, epoxy groups, and any combination thereof.

[0027] Preferably, component B is selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, partially hydrolyzed polyvinyl acetate, functionalized polyvinyl alcohol, functionalized polyvinyl acetate, functionalized partially hydrolyzed polyvinyl acetate, polyvinyl acetal, copolymers of polyvinyl acetate with at least one other monomer, polyvinyl acetate polymers or copolymers having at least one grafted unit, polyurethanes, polyacrylates, polyamides, or combinations thereof. Preferably, the functionalized polyvinyl alcohol and / or the functionalized partially hydrolyzed or non-hydrolyzed polyvinyl acetate are functionalized with an ethylenically unsaturated group, and / or at least one other monomer in the copolymer of polyvinyl acetate is ethylene, and / or at least one grafted unit of the polyvinyl acetate polymer or copolymer is polyethylene glycol.

[0028] With respect to component A, the photosensitive composition may contain one or more additives known to those skilled in the art, examples of which are provided further in the description.

[0029] Further according to the present invention there is provided a developable relief precursor comprising a dimensionally stable carrier layer as layer L1, at least one photosensitive layer as layer L2 and, optionally, one or more additional layers. Layer L2 comprises a photosensitive composition according to the present invention as defined herein, which composition may have components with corresponding properties as described above.

[0030] In a preferred aspect of the present invention, the relief precursor has an AOX value of less than 3.2 mg / L, preferably less than 3 mg / L, more preferably less than 2.8 mg / L, even more preferably less than 2.6 mg / L, the AOX value being determined according to the method as described in Example 2 herein.

[0031] By incorporating the photosensitive composition of the present invention into the relief precursor, isolated dot profiles with diameters of 100 μm or less are possible. This can improve the resolution of printed images. It is believed that the ionic groups in the photosensitive composition improve the relief-forming ability of layer L2, resulting in a higher 1:1 ratio, as evidenced by the examples. As a result, the printing result approaches or achieves a 1:1 image transfer from the source image to the print. Therefore, the resulting improved predictability of the printing ability of the relief structure allows the operator to print more accurately.

[0032] In a preferred embodiment, the photosensitive composition enables the relief precursor to form discrete dot profiles having a diameter difference of less than 14%, preferably less than 12%, more preferably less than 10%, and even more preferably less than 6%, as determined according to the method as described in Example 2.

[0033] Preferably, layer L2 has a thickness in the range of 25 μm to 5000 μm. Preferably, layer L1 comprises a metal sheet, steel, an alloy, a natural or artificial polymer, a polymer blend, a polymer film, or any combination thereof. A preferred layer is a PET layer comprising polyethylene terephthalate, such as a PET film.

[0034] Optional additional layers may be disposed between layers L1 and L2, on top of L2, or both. Possible examples of these layers include a barrier layer, a laser ablatable mask layer, an adhesive layer, a UV / VIS and / or IR light absorbing layer, a monomer diffusion control layer, a surface control layer, a protective layer, a cover foil, a cover film, or a combination thereof.

[0035] Further according to the present invention, there is provided a method for making a developable relief precursor, the method comprising the steps of providing at least one dimensionally stable carrier layer; optionally providing an adhesive layer and / or adhesive treatment on the dimensionally stable carrier layer; providing a photosensitive composition on the at least one dimensionally stable carrier layer; and optionally providing one or more additional layers and / or treatments, wherein the photosensitive composition is a photosensitive composition according to the present invention as defined herein and may have components with corresponding properties as described above.

[0036] Optionally, the one or more treatments are selected from the group comprising a surface treatment, an adhesive treatment, a corona treatment, a flame treatment, a chemical treatment, a plasma treatment, a top surface coating treatment, or a combination thereof.

[0037] The photosensitive compositions of the present invention as described herein are particularly useful for producing relief precursors and / or relief structures. The produced relief structures are preferably used as flexographic printing plates, letterpress plates, pad printing plates, letterpress printing plates, flexible printed wiring boards, electronic devices, microfluidic devices, microreactors, phoretic cells, photonic crystals, optical devices, or Fresnel lenses. Microfluidic devices or microreactors can be obtained by adding additional layers forming channels and reaction chambers on top of the produced relief.

[0038] Further according to the present invention, there is provided a method for producing a relief structure, the method comprising the steps of providing a relief precursor comprising the photosensitive composition of the present invention as described herein, exposing the photosensitive composition to electromagnetic radiation, preferably imagewise, and removing the unexposed areas with the aid of a developer.

[0039] Preferably, the exposing step is performed through an ablated mask layer and / or the exposing step is performed through a mask disposed between the photosensitive layer and the electromagnetic radiation source.

[0040] Regarding the removal of the unexposed areas, this can be achieved by dissolving, emulsifying, and / or dispersing the uncrosslinked areas in the photosensitive layer using a solvent-based or water-based solution, such as an organic solvent, a mixture thereof, water, an aqueous solution, or an aqueous organic solvent mixture. Preferably, the developer is water, one or more aqueous solutions, a polar solvent, or a combination thereof. The aqueous solution may contain an acid, a base, a salt, a solvent, a surfactant, or a combination thereof.

[0041] In the method for producing a relief structure, the inclusion of the photosensitive composition of the present invention in the relief precursor reduces chemical migration into the developer, resulting in a developer having an AOX value of 3.2 mg / L or less, preferably 3 mg / L or less, more preferably less than 2.8 mg / L, and most preferably 2.6 mg / L or less. The AOX value is determined according to the method as described in Example 2.

[0042] In a further aspect of the present invention, there is provided a relief structure obtainable according to the method as described herein, which results in a relief structure having at least one or more of the following properties: the relief structure has an AOX value of less than 3 mg / L, preferably less than 2.8 mg / L, even more preferably less than 2.6 mg / L, said AOX value being determined according to the method as described in Example 2; the relief structure has a curl value of less than 40 mm, preferably equal to or less than 35 mm, the curl value being determined according to the method as described in Example 2. [Brief explanation of the drawings]

[0043] [Figure 1] 1 shows a schematic representation of a developable relief precursor. [Figure 2A] 2A-2B show the principle of development of a relief precursor. [Figure 2B] 2A-2B show the principle of development of a relief precursor. [Figure 3A] 3A-3B show the effect of the improved 1:1 ratio. [Figure 3B] 3A-3B show the effect of the improved 1:1 ratio. [Figure 4A] 4A-4B show the curl phenomenon. [Figure 4B] 4A-4B show the curl phenomenon.

[0044] Detailed Description of the Embodiments A more detailed description of the various aspects of the present invention will enable those skilled in the art to better understand and practice the invention described herein, but is not intended to, and should not, limit the scope of the claims appended hereto. As a further guide, definitions of terms are included to better understand the teachings of the present invention. All terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined.

[0045] As used herein, the terms "photosensitive layer," "radiation-curable layer," "photopolymerizable layer," "radiation-sensitive layer," or "relief-forming layer" can be used interchangeably. Similarly, as used herein, in the terms "photosensitive composition," "radiation-curable layer," "radiation-curable composition," and "photopolymerizable composition," "composition" and "mixture" can be used interchangeably. As used herein, the term "layer" includes "multiple layers" and "layered."

[0046] As used herein, the term "component" refers to a specific molecule or a group of specific molecules that constitute part of the photosensitive composition, relief precursor, and / or relief structure as provided herein, and therefore the term "component" also means "components." A component can include one or more subcomponents; for example, component U can include component E and component EM. Alternatively, for example, component EM can include one or more ethylenically unsaturated monomers that do not have an ionic group. Alternatively, for example, component A, which is an additive, can include one or more additives of the same or different types.

[0047] As used herein, "pbw" stands for parts by weight.

[0048] As indicated hereinabove, one aspect of the present invention is based on the discovery that the introduction of ionic monomers into the photosensitive composition of a developable relief precursor provides unprecedented advantages to this material, and to the relief structures obtained from said precursor, with regard to, inter alia, durability, productivity, and reliability and precision of the patterned surfaces formed on the relief structures.

[0049] It is therefore a first object of the present invention to provide a developable relief precursor photosensitive composition comprising at least one ethylenically unsaturated monomer as Component E, at least one photoinitiator or photoinitiator system as Component P, at least one water-soluble and / or water-dispersible binder as Component B, and optionally one or more additives as Component A, wherein Component E comprises at least one ionic group, and Component E is present in an amount of 0.5 to 30 wt %, based on the total weight of the photosensitive composition.

[0050] Preferably, the developable relief precursor is a water-developable relief precursor.

[0051] As already mentioned earlier in this specification, the inclusion of ionic groups in the ethylenically unsaturated monomers increases the polarity of the photosensitive composition and provides charge to the polymer chains and / or polymer networks formed from the ethylenically unsaturated monomers together with the water-soluble and / or water-dispersible binder and any additives. The formation of the polymer chains and / or networks is initiated by the photoinitiator or photoinitiator system present in the photosensitive composition according to the present invention, in particular upon exposure of the composition to electromagnetic radiation.

[0052] This formation of polymer chains and / or networks hardens and crosslinks the photosensitive composition, thereby creating a structure that provides relief after removal of the unhardened material.

[0053] The use of ionic groups in ethylenically unsaturated monomers, thereby introducing charge into the polymer chains and / or polymer network, reduces the release of harmful chemicals into the surroundings, e.g., the environment and the developer. Furthermore, the time-consuming step of removing unexposed areas is shortened. The compositions of the present invention also increase the flexibility of the relief precursor and the relief structure, reducing the undesirable and troublesome "curl phenomenon." The latter is illustrated in FIG. 4 for a relief precursor comprising a dimensionally stable carrier layer L1, e.g., a PET sheet, and a photosensitive layer L2. In FIG. 4A, the relief precursor is curled, typically due to drying and / or after a period of storage. The corners of the relief precursor curl a distance d from the surface 40 on which the relief precursor rests.

[0054] Not only the monomer itself, but also the photosensitive composition, the relief precursor made with the photosensitive composition, and the resulting relief structure therefrom can better capture and / or avoid harmful chemicals, thereby reducing the tendency of these chemicals to get into the surroundings, especially the environment and the developer, which can also be called a washout solution. Typically, such harmful chemicals are organohalogens, which can be understood as chemicals containing one or more covalently bonded halogens, such as fluorine, chlorine, bromine, iodine, optionally combined with carbon and other elements.

[0055] Preferably, ionic monomers are synthesized by esterification with acrylic acid or methacrylic acid, and the use of organic chlorides, such as epichlorohydrin, is reduced or avoided, so that the content of organic halogens in the synthesized ionic monomers can be reduced.Another option is a simpler and more effective cleaning procedure to remove harmful chemicals during synthesis.The lower the content of these harmful components in the photosensitive composition, the less likely these harmful chemicals are to be transferred to the developer, thereby reducing the risk of release into the environment, especially when disposing of the developer.

[0056] Furthermore, the composition of the present invention shortens the time-consuming step of removing the unexposed areas. The introduction of ionic groups into the composition increases polarity, allowing the developer to penetrate the composition more easily and disperse or dissolve the unexposed areas of the photosensitive composition more quickly. Preferred developers are water, aqueous solutions, and polar solvents. The aqueous solutions may contain acids, bases, salts, other solvents, surfactants, or combinations thereof.

[0057] The photosensitive composition of the present invention also enhances the flexibility of the relief precursor, the flexibility of the polymer chains formed, and the flexibility of the polymer network formed. This affects the properties of the resulting relief structure after development, such as its usable life and flexibility. The charges in the polymer chains and polymer network affect the swelling ability of the relief precursor in an aqueous medium, allowing it to better retain or absorb water molecules. This enhances the mechanical durability and flexibility of the relief precursor, reducing deformations, such as cracks or other types of breakage, present in the relief structure, especially after exposure. In addition, the improved mechanical durability and flexibility allow for an extended usable life with one and the same relief structure. The relief structure is more resistant to mechanical degradation or structural loss during intensive printing, for example, due to high printing speeds or high printing pressures on the printing substrate, the hardness of the printing substrate, etc.

[0058] Furthermore, the buildup of intrinsic stresses, primarily observed during the formation of the relief structure, is influenced by the photosensitive composition, particularly during and after exposure of the relief precursor, where polymer chains and / or polymer networks are formed. Typically, intrinsic stress differences exist in the relief precursor, and even larger stress differences exist in the relief structure due to the curing and crosslinking of the photosensitive composition after exposure. The incorporation of charges into the polymer chains and / or polymer network reduces the curling phenomenon caused by intrinsic stress differences. An example of this phenomenon is shown in Figure 4, where Figure 4B shows a relief precursor RP with curled side edges.

[0059] Additionally, it has been observed that the presence of the photosensitive composition of the present invention can achieve an increase in the surface energy of the relief structure, thereby reducing the contact angle of the ink applied to the relief structure, which improves the wetting of the surface and, as a result, improves ink transfer. The inclusion of the photosensitive composition of the present invention in the relief structure increases the polarity of the surface, thereby improving the wetting of the ink when applied to the surface of the relief structure. This is particularly advantageous for polar inks. The increased wetting allows the ink to be transferred more accurately and predictably from the relief structure to the printing substrate. Furthermore, the relief precursor and the relief structure have been found to exhibit antistatic and antifouling, and / or antibacterial properties.

[0060] To provide those skilled in the art with a better teaching of the photosensitive composition, the components are described in further detail below.

[0061] (Component E, ethylenically unsaturated monomer) With regard to Component E, it is preferred that it be present in an amount of 0.5 to 30 wt %, preferably 0.5 to 25 wt %, based on the total weight of the photosensitive composition. More preferably, Component E is present in an amount of 1 to 20 wt %, and even more preferably 5 to 20 wt %. This wt % concentration has been found to provide the best results, as Component E affects, among other things, the swelling ability, water solubility, and flexibility of the photosensitive composition, and higher concentrations tend to increase the water solubility of not only the unexposed regions of the photosensitive composition, but also the exposed regions. Higher water solubility of the cured photosensitive composition, especially the exposed areas, can result in the cured photosensitive composition being washed away during development of the relief precursor, so water solubility should not be too high. Additionally, higher concentrations can cause swelling of the relief structure to an undesirable extent. This can affect the accuracy of the relief structure and the reliability of printing performance, especially when printing with aqueous inks.

[0062] In a preferred embodiment, component E has a solubility in water of 200 g / l or more, preferably in the range of 500 to 1500 g / l, in water at 20°C and 1 atmosphere, pH 7, in order to achieve faster wash-off times and thereby speed up the overall development process or manufacturing method of the relief structure.

[0063] In certain embodiments, component E preferably has a molecular weight in the range of 100 to 1000 g / mol, more preferably in the range of 110 to 500 g / mol, and even more preferably in the range of 120 to 300 g / mol. The molecular weight of the monomer influences, among other things, the polymer chain length and crosslink density. These ranges are preferred to achieve desired properties, such as reducing cleaning times to allow for more rapid removal of unexposed areas of the relief precursor. Additionally, these ranges allow the resulting polymer chains and / or network to have a desired degree of flexibility, which improves the properties of the relief precursor and the relief structure.

[0064] In one embodiment, component E comprises at least one of an acrylate group, a methacrylate group, an acrylamide group, a vinyl group, a vinyl ether group, or a combination thereof. These groups are particularly preferred because they provide desirable results regarding the polymerization and crosslinking of the photosensitive composition and exhibit adequate compatibility with other components present in the photosensitive composition. Preferably, component E comprises an acrylate group or a methacrylate group. In one embodiment, component E may comprise two or more ethylenically unsaturated groups.

[0065] In one embodiment, component E has a vapor pressure of less than 50 hPa at 25°C. The vapor pressure is determined in accordance with the ASTM E1194-17 standard for vapor pressures less than 1 Pa and in accordance with ASTM D2879-18 for vapor pressures equal to or greater than 1 Pa. In a more preferred embodiment, a vapor pressure of less than 45 hPa, more preferably less than 40 hPa, is preferred. These vapor pressures should not be too high for environmental reasons and for reasons related to the ease, comfort, and health of operators handling any one of the components, the photosensitive composition, the relief precursor, and the relief structure. In addition, the lower the vapor pressure, the less of the typical, rather unpleasant chemical odor present when handling the photosensitive composition, the relief precursor, and the relief structure.

[0066] In certain embodiments, component E has an EOX value of less than 2000 mg / kg, preferably less than 200 mg / kg, and more preferably less than 50 mg / kg. The EOX value is determined according to the DIN 38414-17 standard using i-hexane as the solvent. This value indicates the extractable organic halogens, hence the name EOX. By selecting the above range, the risk of harmful chemicals being transferred to the surroundings, the developer, and the environment is reduced.

[0067] In certain embodiments, component E has an AOX value of less than 2600 mg / L, preferably less than 1000 mg / L, and more preferably less than 100 mg / L. The AOX value is determined in accordance with the "DIN EN ISO 9562" standard and indicates the amount of adsorbable organic halides, hence the name AOX. The determination of the AOX value was carried out in accordance with Section 6.2.1. By selecting these ranges, the risk of migration of harmful chemicals into the surroundings, the developer, and the environment is reduced.

[0068] In a preferred embodiment, at least one ionic group contained in Component E is selected from the group consisting of a quaternary ammonium group, a carboxylate group, a sulfonate group, a sulfonium group, a phosphonium group, and combinations thereof. In one embodiment, Component E may contain two or more types of ionic groups. When multiple types of ionic groups are present, the multiple types of groups may be anionic or cationic. In addition, a combination in which both anionic and cationic groups are present in the same ethylenically unsaturated monomer is also possible, and both groups having respective charges may form an intermolecular salt or may have a counterion that balances the respective charges.

[0069] Quaternary ammonium cations are preferred due to their pH independence with respect to charge. Quaternary ammonium cations are permanently charged and can have the formula: 1 ~R 3 any one of R can independently represent an alkyl, aryl, or alicyclic group; 4 represents an alkyl, aryl, or alicyclic group substituted with an ethylenically unsaturated group.

[0070] [ka]

[0071] Carboxylate groups are preferred because they have high solubility in polar solvents, thereby reducing cleaning times, and can have the following formula, where R represents an alkyl or aryl group substituted with an ethylenically unsaturated group:

[0072] [ka]

[0073] Sulfonate groups are preferred due to their stability in the developer and are non-oxidizable, where R represents an alkyl or aryl group substituted with an ethylenically unsaturated group.

[0074] [ka]

[0075] The sulfonate group has a sulfonium group and is preferred for its solubility in organic solvents. 1 ~R 2 any one of R can independently represent an alkyl, aryl, or alicyclic group; 3 represents an alkyl group or an aryl group substituted with an ethylenically unsaturated group.

[0076] [ka]

[0077] The phosphonium group can be represented by the formula: 1 ~R 3 any one of R can independently represent an alkyl, aryl, or alicyclic group; 4 represents an alkyl group or an aryl group substituted with an ethylenically unsaturated group.

[0078] [ka]

[0079] In a preferred aspect of the present invention, component E is a quaternized amino-functional monomer. Such monomers can act as cationic detergents, reducing undesirable phenomena such as sedimentation when washing the relief precursor during the development process. In addition, monomers with cationic groups interact less with calcium, which is often present in inks, than monomers with anionic groups.

[0080] Typically, this component E is added to the photosensitive composition in an aqueous solution, although those skilled in the art will appreciate that other techniques can be used to add the monomer to the photosensitive composition. Preferably, when an aqueous solution is used, the water content of the aqueous solution ranges from 0 to 60%, preferably from 5 to 50%, and the preferred pH of the aqueous solution is from 3 to 9, more preferably from 3 to 7. The pH value can be measured by commonly known techniques.

[0081] In certain preferred embodiments, the following ethylenically unsaturated monomers are used: 2-trimethylammoniumethyl methacrylate chloride (TMAEMC), methacrylamidopropyltrimethylammonium chloride (MAPTAC), also known as 3-methacrylamido-N,N,N-trimethylpropane-1-aminium chloride, acryloxyethyltrimethylammonium chloride (ADAMQUAT), sodium salt of 2-acrylamido-2-methylpropanesulfonic acid (Na-AMPS).

[0082] TMAEMC comprises 2-trimethylammonium ethyl methacrylate chloride and may be used to prepare water-soluble cationic polymers in photosensitive compositions. This compound is available, for example, from Evonik Industries AG under the trade name VISIOMER® TMAEMC as an aqueous solution with a solids content of around 75%, and has the following chemical formula and a molecular weight of 207.7 g / mol:

[0083] [ka]

[0084] MAPTAC includes methacrylamidopropyltrimethylammonium chloride, also known as 3-methacrylamido-N,N,N-trimethylpropan-1-aminium chloride. This compound is used to impart cationic charge to polymer chains in photosensitive compositions. This compound is available, for example, from Evonik Industries AG under the trade name Bishomer® MAPTAC as an aqueous solution with a solids content of approximately 50%. It has the following chemical formula and a molecular weight of 220.5 g / mol:

[0085] [ka]

[0086] ADAMQUAT contains the cationic monomer acryloxyethyltrimethylammonium chloride and is used to impart a cationic charge to the polymer in the photosensitive composition. This component is available, for example, from Arkema SA under the trade name ADAMQUAT MC80 as an aqueous solution with a solids content of around 80%, and has the following chemical formula and a molecular weight of 193.67 g / mol:

[0087] [ka]

[0088] Na-AMPS contains the sodium salt of 2-acrylamido-2-methylpropanesulfonic acid, which provides an anionic charge to the polymer chains in the photosensitive composition. This component is available, for example, from Sigma-Aldrich Chemie GmbH as an aqueous solution with a solids content of approximately 50%. It has the following chemical formula and a molecular weight of 229.23 g / mol:

[0089] [ka]

[0090] Also, with regard to ethylenically unsaturated monomers, the following components may be used: DMAEMDMS, trimethyl({2-[(2-methylprop-2-enoyl)oxy]ethyl})azanium methyl sulfate, which can be represented by the following formula and has a molecular weight of 283.343 g / mol.

[0091] [ka]

[0092] PSPA, 3-sulfopropyl acrylate potassium salt, which can be represented by the formula below and has a molecular weight of 232.30 g / mol.

[0093] [ka]

[0094] Zwitterionic or betaine monomers may also be used as the ethylenically unsaturated monomer. A suitable zwitterionic monomer is dimethyl({2-[(2-methylprop-2-enoyl)oxy]ethyl})(3-sulfopropyl)azanium hydroxide, which has the following chemical formula:

[0095] [ka]

[0096] Another suitable zwitterionic monomer is 2-ethenyl-1-(3-sulfopropyl)pyridin-1-ium, which has the following formula:

[0097] [ka]

[0098] [Counter ion] The photosensitive composition is electrically neutral and typically includes a counterion present in the photosensitive composition as Component I. When at least one ionic group in Component E is cationic, Component I is selected from an anionic group. Alternatively, when at least one ionic group in Component E is anionic, Component I is a cationic group. Alternatively, Component E can have zwitterionic properties, in which case the counterion may be selected from either anionic or cationic groups, or both. For ink compatibility reasons, it is preferred that Component E includes a cationic group; for example, anionic groups may interact with calcium ions present in the ink, so the counterion is preferably cationic to prevent such interactions.

[0099] Component I may be selected from anionic groups including chloride, bromide, iodide, fluoride, sulfonate, methylsulfate, sulfate, tosylate, nitrate, halogen anions, sulfonium anions, tosylate anions, borate anions, nitrate anions, methylsulfate anions, halogen anions, or combinations thereof; Component I may be selected from cationic groups including ammonium, sodium, aluminum, calcium, cesium, chromium, copper, barium, iron, lead, lithium, magnesium, nickel, potassium, rubidium, silicon, silver, strontium, titanium, zinc, zirconium, ammonium cations, alkali cations, earth alkali cations, phosphonium cations, sulfonium cations, or combinations thereof.

[0100] Further examples of compounds suitable for component E are given below.

[0101] Salts of methacrylic acid, such as sodium 2-methylprop-2-enoate, aluminum(3+) tris(2-methylprop-2-enoate), ammonium 2-methylprop-2-enoate, calcium bis(2-methylprop-2-enoate), bis(methacrylate-O)chromium, copper bis(2-methylprop-2-enoate), barium bis(2-methylprop-2-enoate), 2-methylprop-2-enoic acid, iron(III) salts, 2-methylprop-2-enoic acid, lead salts, 2-methylprop-2-enoic acid, lithium salts, malic acid, Magnesium bis(2-methylpropan-2-olate), nickel 2-methylprop-2-enoate, potassium 2-methylprop-2-enoate, 2-methylprop-2-enoic acid, rubidium salt, 2-methylprop-2-enoic acid, silicon salt, 2-methylprop-2-enoic acid, silver salt, 2-methylprop-2-enoic acid, strontium salt, 2-methylprop-2-enoic acid, titanium(IV) salt, 2-methylprop-2-enoic acid, zinc salt, zirconium(4+) tetrakis(2-methylprop-2-enoate) are further examples for component E.

[0102] Salts of acrylic acid, such as 3-sulfopropyl acrylate, potassium salt, ammonium prop-2-enoate, 2-propenoic acid, sodium salt, 2-propenoic acid, aluminum salt, 2-propenoic acid, barium salt, 2-propenoic acid, calcium salt, 2-propenoic acid, cesium salt, 2-propenoic acid, chromium(III) salt, 2-propenoic acid, copper(II) salt, 2-propenoic acid, iron(III) salt, 2-propenoic acid, lead salt, 2-propenoic acid, lithium salt, 2-propenoic acid, magnesium salt, 2-propenoic acid, nickel(II) salt, 2-propenoic acid, potassium salt, 2-propenoic acid, silver salt, 2-propenoic acid, strontium salt, 2-propenoic acid, zinc salt, 2-propenoic acid, zirconium salt, potassium acrylate, rubidium acrylate are further examples for component E.

[0103] Vinyl / allyl type salts such as allyltriethylammonium iodide, allyltrimethylammonium bromide, diallyldimethylammonium chloride, 1-(3-sulfopropyl)-2-vinylpyridinium betaine, p-vinylbenzyltrimethylammonium chloride are further examples for component E.

[0104] (Component EM, an ethylenically unsaturated compound that does not contain ionic groups) In one embodiment, the photosensitive composition further comprises at least one ethylenically unsaturated compound as component EM that does not contain an ionic group. Contemplated ethylenically unsaturated compounds are those that are compatible with the polymer binder or binders of component B. The ethylenically unsaturated compound preferably contains at least two ethylenically unsaturated groups, more preferably two to six ethylenically unsaturated groups, and even more preferably exactly two ethylenically unsaturated groups. Compounds with a C—C triple bond can also be used in the photosensitive composition. Component EM is preferably an acrylate and / or methacrylate group, although acrylamide, vinyl ether, or styrene derivatives can also be employed as the ethylenically unsaturated compound. The ethylenically unsaturated compound without an ionic group may be a monomeric, oligomeric, or polymeric ethylenically unsaturated compound and may have a linear, branched, star-shaped, or dendritic structure. In one embodiment, component EM has a low molecular weight of less than 5000 g / mol, preferably less than 3000 g / mol, more preferably less than 1000 g / mol, very preferably less than 500 g / mol, and may even be less than 300 g / mol, but preferably at least 72.06 g / mol, more preferably at least 86 g / mol.

[0105] Preferred ethylenically unsaturated compounds as component EM are derivatives of acrylic and / or methacrylic acid, for example their esters with mono- or polyhydric alcohols, examples of which are acrylic or methacrylic acid esters of alkanols having 1 to 20 carbon atoms, such as methyl methacrylate, ethyl acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate. acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, (meth)acrylic acid esters of polyhydric alcohols having 2 to 20 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, butane-1,4-diol di(meth)acrylate 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, or pentaethylene glycol di(meth)acrylate. Lithritol tetra(meth)acrylate, as well as poly(ethylene oxide) di(meth)acrylate, m-methyl poly(ethylene oxide)-yl (meth)acrylate, N,N-diethylaminoethyl acrylate, reaction products of 1 mol of glycerol, 1 mol of epichlorohydrin, and 3 mol of acrylic acid, glycidyl methacrylate, and bisphenol A diglycidyl ether acrylate, (meth)acrylic acid derivatives with carboxylic acid and / or amino groups.

[0106] Further particularly preferred compounds as component EM are derivatives of acrylamide and methacrylamide, such as ethers, oligomeric or polymeric ethylene oxide derivatives of their N-methylol derivatives with monohydric and polyhydric alcohols, such as ethylene glycol, glycerol or 1,1,1-trimethylolpropane. These compounds are particularly preferred when polyamides or polyvinyl alcohols are used as binders in the photosensitive composition.

[0107] Further preferred compounds as component EM are the so-called epoxy (meth)acrylates and urethane (meth)acrylates, for example of the type obtainable by reaction of bisphenol A diglycidyl ether with (meth)acrylic acid or by reaction of diisocyanates with hydroxyalkyl (meth)acrylates or hydroxyl-containing polyesters or polyethers.

[0108] Other preferred compounds that can be used as component EM are ethylenically unsaturated compounds, such as esters of acrylic or methacrylic acid, especially those with a pressure at 25°C predicted by QSAR MPBPWIN v.143 (modified Grain method) of less than 10 Pa, even more preferably less than 1 Pa, and those modified with compatibilizers, such as hydroxyl, amide, sulfoester or sulfonamide groups.

[0109] Further preferred compounds as component EM are phenyl glycidyl ether acrylate, glycerol dimethacrylate, 1,4-butanediylbis[oxy(2-hydroxy-3,1-propanediyl)]diacrylate, 2-hydroxyethyl methacrylate, 2,3-epoxypropyl methacrylate, ethyl diglycol acrylate, hydroxypropyl acrylate, butanediol diacrylate, triethylene glycol diacrylate, bisphenol A diglycidyl ether diacrylate, 2-(dimethylamino)ethyl methacrylate, tert-butylaminoethyl methacrylate, tert-butyl acrylate, polyethylene glycol methacrylate, benzyl acrylate, tetrahydrofurfuryl acrylate, phenoxymethyl methacrylate, vinylpyrrolidone, and vinyl acetate, as well as the corresponding methacrylates.

[0110] Further, preferred compounds for component EM are phenyl glycidyl ether acrylate, glycerol diacrylate, 1,4-butanediylbis[oxy(2-hydroxy-3,1-propanediyl)]diacrylate, ethylene diacrylate, 2-hydroxyethyl methacrylate, butanediol diacrylate, hexanediol diacrylate, and the corresponding methacrylates. In one embodiment, the photosensitive composition contains phenyl glycidyl ether acrylate. Furthermore, mixtures or combinations of the preferred compounds mentioned above for component EM may be used, and preferably mixtures of the copolymerizable ethylenically unsaturated organic compounds described above.

[0111] In a preferred embodiment, the ethylenically unsaturated monomer containing an ionic group as component E and the ethylenically unsaturated compound without an ionic group as component EM are present together in the photosensitive composition in an amount ranging from 0.5 to 50 wt %, preferably from 1 to 40 wt %, more preferably from 5 to 40 wt %, and even more preferably from 10 to 40 wt %, based on the total weight of the photosensitive composition. Particularly preferred is a ratio (concentration of component EM / concentration of component E), hereinafter referred to as the "EM / E ratio," of between 0.1 and 10, more preferably between 0.15 and 8, and even more preferably between 0.2 and 5. Here, component EM comprises an ethylenically unsaturated monomer compound or compounds without an ionic group as described herein, or a combination of components described as component EM. And component E comprises a component with an ionic group as described herein, or a combination of components described above as component E.

[0112] In one embodiment, component E is present in an amount of 11 to 21 pbw based on the total formulation and / or at a concentration of 1.5 to 21 wt %, which concentrations provide fast cleaning times.

[0113] In one embodiment of the present invention, the EM / E ratio is less than 4.6, preferably less than 4. This ratio has been found to best reduce the undesirable curl phenomenon.

[0114] (Component P, Photoinitiator or Photoinitiator System) The photoinitiator or photoinitiator system is selected to be particularly responsive to electromagnetic radiation in the UV range of the electromagnetic spectrum. Without being bound by any particular polymerization reaction, the present invention will be described according to the principles of radical polymerization. However, as those skilled in the art will understand, different mechanisms and several side reactions are possible, e.g., anionic or cationic polymerization reactions may exist to a greater or lesser extent. The photoinitiator or photoinitiator system initiates the polymerization reaction by forming radicals under the influence of UV light, typically between 100 and 400 nm, and more preferably between about 385 and 395 nm, thereby influencing the curing and crosslinking of the photosensitive composition. In particular, the photoinitiator or photoinitiator system is selected according to the principles of curing and crosslinking using UV LED technology. As those skilled in the art will understand, typical conventional methods using standard lamps, such as mercury lamps, can also be used, since these lamps emit a wide spectrum of electromagnetic radiation. In one embodiment, component P includes one or more polymerization photoinitiators. A suitable initiator or initiator system is composed of at least two components that generate radicals that result in polymerization and / or crosslinking upon irradiation with electromagnetic waves.Initiators of this type are known to those skilled in the art and are described in the following references: Bruce M. Monroe et al., Chemical Review, 93, 435 (1993); R. S. Davidson, Journal of Photochemistry and Biology A: Chemistry, 73, 81 (1993); M. Tsunooka et al., 25 Prog. Polym. Sci., 21, 1 (1996); F.D. Saeva, Topics in Current Chemistry, 156, 59 (1990); G.G. Maslak, Topics in Current Chemistry, 168, 1 (1993); H.B. Shuster et al., JACS, 112, 6329 (1990); and I.D. Featon et al., JACS, 102, 3298 (1980); P. Fouassier and J.F. Rabek, Radiation Curing in Polymer Science and Technology, pages 77-117 (1993) or KKDietliker, Photoinitiators for free Radical and Cationic Polymerisation, Chemistry&Technology of UV&EB Formulation for Coatings, InksandPaints, Volume, 3, Sita Technology LTD, London 1991; or RS Davidson, Exploring the Science, Technology and Applications of UVand EBCuring, Sita Technology Ltd., London 1999.Further initiators are described in JP 45-37377, JP 44-86516, U.S. Pat. No. 3,567,453, U.S. Pat. No. 4,343,891, EP 109772, EP 109773, JP 63138345, JP 63142345, JP 63142346, JP 63143537, JP 4642363, JP 59152396, JP 61151197, JP 6341484, JP 2249 and JP 24705, JP 626223, JPB 6314340, JP 1559174831, JP 1304453, and JP 1152109. Preferred initiators or initiator systems comprised of at least two components are also known as initiator groups, generally known as Norrish type I or Norrish type II, or components capable of carrying out electron transfer reactions upon irradiation. Norrish type I initiators include, for example, benzoyl radical-forming initiators, α-hydroxyketones, α-aminoketones, acylphosphine oxides, bisacylphosphine oxides, triazines, and hexaarylbisimidazoles, which may be further combined with dyes or sensitizers to enhance sensitivity. Norrish type II initiators are, in particular, combinations of ketones or aldehydes with H-transfer agents, such as amines or thiols.

[0115] With respect to component P, it is preferred to select said component P from the group including benzil ketals, hydroxyketones, aminoketones, acylphosphine oxides, bisacylphosphine oxides, thioxanthones, anthraquinones, coumarins, hexaarylbisimidazoles, benzophenones, and combinations thereof. These groups result in a suitable degree of radical formation and are suitable for low irradiation doses, preferably 16-20 Watts / cm, although even lower ranges may be possible. 2

[0033] Preferred initiators are benzil dimethyl ketal, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoylphenylphosphinate, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,-1,4-trimethylpentyl)phosphine oxide, Michler's ketone, and benzophenone, alone and / or in combination with a sensitizer, an amine, or a thiol, and any desired combination thereof. Further suitable initiators are onium salts, organic peroxides, thio compounds, ketoximes, borates, azinium compounds, azo compounds, metallocenes, and compounds having a carbon-halogen group, which may likewise be used in combination or together with a sensitizer, an amine, or a thiol. Examples of usable sensitizers include xanthone, thioxanthone, anthracene, perylene, phenothiazine, benzophenone, acetophenone, and dyes. Sensitization requires either a higher triplet energy of the sensitizer than the initiator to be sensitized, or electron transfer from the excited state of the sensitizer is possible. Furthermore, component P may be a photoinitiator system further comprising a coinitiator selected from the group consisting of amines, thiols, thioethers, aminoalcohols, thioetheramines, and combinations thereof. Combinations of several of the above photoinitiators can be used to initiate curing at different wavelength ranges, resulting in faster curing than with a single photoinitiator. The wavelength of the electromagnetic radiation is in the range of 200-2000 nm, preferably in the UV range, more preferably in the range of 250-550 nm, and most preferably in the range of 300-450 nm. In addition to broadband electromagnetic radiation, it may be advantageous to use narrowband or monochromatic wavelength ranges of the kind that can be generated using corresponding filters, lasers, or light-emitting diodes (LEDs). In such cases, wavelengths in the ranges of 350, 365, 385, 395, 400, 405, 532, 830, and 1064 nm (and around 5-10 nm above and below these) are preferred, either individually or in combination.The initiator or initiator combination representing component P has at least one absorption maximum within these wavelength ranges. The absorption maximum of the photoinitiator and / or photoinitiator system does not necessarily have to coincide with the emission maximum of the electromagnetic radiation, although it is advantageous if the two maxima overlap to a very high degree. Two or more different photoinitiators, each with a different absorption maximum, can also be selected, thereby responding to a set of different wavelength ranges. In one embodiment, the photosensitive composition contains component P in an amount of 0.1 to 20 wt %, based on the total formulation. The initiator concentration is preferably 0.1 to 10 wt %, more preferably 0.1 to 5 wt %, and even more preferably 0.5 to 5 wt %.

[0116] (Component B, Water-soluble and / or Water-dispersible Binder) The water-soluble and / or water-dispersible binder contained in the photosensitive composition can be reactive and functional, thereby having groups that can crosslink during the polymerization or curing reaction. Additionally or alternatively, the binder can be a non-reactive binder. Preferably, the binder is crosslinkable with the polymer chain formed by component E, i.e., the ethylenically unsaturated monomer, and / or with other additives. To balance the final properties of the relief precursor and the resulting relief structure, both reactive and non-reactive binders can be combined. The binder can be linear, branched, star-shaped, or dendritic, and both can exist as homopolymers, statistical copolymers, block copolymers, or alternating copolymers.

[0117] Binders very often have functional groups that enhance solubility and / or can participate in crosslinking reactions, such as carboxy groups, SO groups, OH groups, thiol groups, ethylenically unsaturated (meth)acrylate groups, epoxy groups, and any combination thereof.

[0118] In one embodiment, component B is selected from the group consisting of polyvinyl alcohol, polyvinyl acetate, partially hydrolyzed polyvinyl acetate, functionalized polyvinyl alcohol, functionalized polyvinyl acetate, functionalized partially hydrolyzed polyvinyl acetate, polyvinyl acetal, copolymers of polyvinyl acetate and at least one other monomer (e.g., ethylene, propylene, or vinyl hexanoate, vinyl propionate, or vinyl n-butyrate), polyvinyl acetate polymers or copolymers having at least one grafted unit, polyurethanes, polyacrylates, polyamides, or combinations thereof. Preferably, the functionalized polyvinyl alcohol and / or the functionalized partially hydrolyzed or non-hydrolyzed polyvinyl acetate are functionalized with an ethylenically unsaturated group, and / or at least one other monomer in the copolymer of polyvinyl acetate is ethylene, and / or at least one grafted unit of the polyvinyl acetate polymer or copolymer is polyethylene glycol. The preparation of partially hydrolyzed functionalized polyvinyl acetate is known and is described, for example, in USRE 2740, DE 3015419, EP 0079514, DE 3322993, DE 3322994, EP 849635, EP 962828, and WO 2019106082, which are incorporated herein by reference. Photosensitive compositions and the relief structures produced therefrom are likewise known and are described, for example, in DE 3015419, EP 0079514, DE 3322993, DE 3322994, EP 849635, and EP 962828, which are incorporated herein by reference.

[0119] The total amount of component B in the photosensitive composition is preferably 30 to 90% by weight, more preferably 40 to 85% by weight, and particularly preferably 45 to 85% by weight, based on the total of all components of the photosensitive composition.

[0120] Additional or alternative suitable binders are further described below. DE 3015419 describes the use of functionalized, partially hydrolyzed polyvinyl acetate in an adhesion-promoting interlayer between a dimensionally stable carrier layer and a photosensitive layer. EP 0079514 shows the use of functionalized, partially hydrolyzed polyvinyl acetate obtained by an excess of functionalizing agent in relief structures, with the aim of improving stability after drying.

[0121] DE 3322993 and DE 3322994 describe an improved process for the preparation of functionalized, partially hydrolyzed polyvinyl acetate by the use of a catalyst and describe the use of functionalized, partially hydrolyzed polyvinyl acetate for the production of relief structures. EP 849635 describes a radiation-curable mixture comprising two different binders, one of which is a highly functionalized, partially hydrolyzed polyvinyl acetate.

[0122] EP 962828 describes further improvements in the synthesis of functionalized, partially hydrolyzed polyvinyl acetate and its use in radiation-curable mixtures for producing relief structures. WO 2018141644 describes the use of functionalized, partially hydrolyzed polyvinyl acetate, preferably used as a reactive binder, in photosensitive compositions for relief precursors. The binder may also be a fully or partially hydrolyzed polyvinyl ester, such as partially hydrolyzed polyvinyl acetate, a polyvinyl alcohol derivative, such as partially hydrolyzed vinyl acetate / alkylene oxide graft copolymer, or a mixture thereof. The binder may also be a polyamide soluble in water or a water / alcohol mixture, such as those described in EP 0085472 or DE 1522444.

[0123] The concentration of additional or alternative suitable binders, if present, is generally in the range of 1 to 50 wt %, preferably in the range of 1 to 40 wt %, more preferably in the range of 1 to 35 wt %, and most preferably in the range of 1 to 30 wt %, based on the total formulation of the photosensitive composition.

[0124] (Component A, optional additives) In one embodiment, the photosensitive composition may include one or more additives selected from the group consisting of plasticizers, solvents, additional polymeric binders, colorants, stabilizers, inhibitors, thermal inhibitors, chain transfer agents, UV absorbers, dispersing aids, organic or inorganic fillers, additional non-radical crosslinkers, viscosity modifiers, and hydrogen bond accepting additives.

[0125] In one embodiment, the additives are present in the photosensitive composition in an amount ranging from 0.001 to 50 wt%, more preferably from 0.01 to 40 wt%, even more preferably from 0.1 to 30 wt%, and most preferably from 1 to 20 wt%, based on the total formulation of the photosensitive composition. Individual additives may be included in concentrations ranging from 0.001 to 30 wt%, preferably from 0.001 to 20 wt%, more preferably from 0.001 to 10 wt%, and most preferably from 0.001 to 5 wt%, based on the total formulation of the photosensitive composition.

[0126] In one embodiment, plasticizers are present in the composition, such as polyethylene glycol, glycerol, ethylene glycol, N-alkylbenzenesulfonamide, phthalate, and any desired mixture thereof.Other examples of suitable plasticizers are aliphthalic acid esters, such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl caprylyl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butylbenzyl phthalate, diisodecyl phthalate or diallyl phthalate; glycol esters, such as dimethyl glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate or are triethylene glycol dicaprylate; phosphate esters such as tricresyl phosphate or triphenyl phosphate; aliphatic diesters such as diisobutyl adipate, dioctyl adipate, dimethyl sebaacetate, dibutyl sebaacetate, dioctyl azelate or dibutyl maleate; pentaerythritol polyoxyethylene ether; polyglycidyl methacrylate; triethyl citrate; glycerol triacetyl ester, and butyl laurate. The content of the plasticizer is 1 to 30 wt %, preferably 1 to 20 wt %, more preferably 1 to 10 wt %, and most preferably 3 to 10 wt %, based on the total weight of the photosensitive composition.

[0127] In one embodiment, a thermal polymerization inhibitor is present that preferably does not exhibit significant intrinsic absorption in the actinic range corresponding to the absorbance spectrum of the photoinitiator or photoinitiator system, such as 2,6-di-tert-butyl-p-cresol, hydroquinone, p-methoxyphenol, β-naphthol, phenothiazine, pyridine, nitrobenzene, m-dinitrobenzene, or chloranil; thiazine dyes such as thionine blue G (CI 52025), methylene blue B (CI 52015), or toluidine blue (CI 52040); or N-nitrosamines such as N-nitrosodiphenylamine or salts of N-nitrosocyclohexylhydroxylamine, for example, potassium, calcium, or aluminum salts. Other suitable inhibitors and stabilizers are described, for example, in A. Valet, Lichtschutzmittel fur Lacke, 33ff, Vincentz Verlag Hannover 1996. Particularly preferred are sterically hindered phenols and amines.

[0128] In one embodiment, a colorant is added to the photosensitive composition, which may be a dye, pigment, or photochromic additive. Preferably, the colorant is added in an amount of 0.0001 to 2 wt % based on the composition. Suitable colorants include soluble phenazinium, phenoxazinium, acridinium, and phenothiazinium dyes, such as Neutral Red (CI 50040), Safranin T (CI 50240), Rhodanyl Blue, salts or amides of Rhodamine D (Basic Violet 10, CI 45170), Methylene Blue B (CI 52015), Thionin Blue G (CI 52025), Acriflavine (CI 46000), Acridine Orange (CI 46005), or Solvent Black 3 (CI 26150). These colorants act as chain transfer agents to control exposure characteristics and / or are used for identification, direct control of exposure results, or aesthetic purposes.

[0129] In one embodiment, the dye may also be used with a reducing agent that does not reduce the dye in the absence of actinic light but can reduce the dye to an excited electronic state upon exposure to light. Examples of such reducing agents include ascorbic acid, anethole, thiourea, such as diethylallylthiourea, especially N-allylthiourea, and salts of hydroxylamine derivatives, especially N-nitrosocyclohexylhydroxylamine, preferably potassium, calcium, and aluminum salts. The reducing agent can act as an inhibitor of thermally initiated polymerization. The reducing agent may generally be added in an amount of 0.005 to 5 wt % based on the composition, and in many cases, an amount 3 to 10 times the amount of the dye used has been found to be appropriate.

[0130] In one embodiment, chain transfer agents, also called modifiers or regulators, may be added to control the polymer chain length during the curing reaction to achieve specific mechanical and processing properties. Suitable chain transfer agents include, for example, hydroxylamine derivatives, especially salts of N-nitrosocyclohexylhydroxylamine, preferably potassium, calcium, and aluminum salts, or -SH-containing compounds such as mercaptoethanol, mercaptopropanol, thiophenol, thioglycerol, ethyl thioglycolate, methyl thioglycolate, dodecyl mercaptan, or mercaptoacetic acid, and organic halogen compounds such as tetrachloromethane.

[0131] In one embodiment, the UV absorbers employed are compounds such as hydroxyphenylbenzotriazoles, hydroxybenzophenones, hydroxyphenyl-s-triazines, oxalanilides, hydroxyphenylpyrimidines, salicylic acid derivatives, and cyanoacrylates, and any desired combinations thereof, as described in A. Valet, Lichtschutzmittel fur Lacke, 20ff, Vincentz Verlag Hannover 1996. UV absorbers in the photosensitive composition can likewise be advantageous and can have a positive effect on the formation of the relief.

[0132] In one embodiment, dispersing aids may be added to the photosensitive composition. These aids improve the dispersion of components such as pigments, dyes, nanoparticles, or inorganic fillers that may be present in the composition. Exemplary dispersing aids are mono- and polyfunctional carboxylic or sulfonic acids, alcohols, or amines. Additional non-radical crosslinking crosslinkers may be used in the radiation-curable mixture, including mono- and polyfunctional aldehydes, polyfunctional epoxides, polyfunctional carboxylic acids, and polyfunctional carboxylic acid anhydrides, as well as any desired combinations. These include, in particular, formaldehyde, acetaldehyde, propylaldehyde, valeraldehyde, caproaldehyde, pivalaldehyde, glyoxal, glutaraldehyde (1,5-pentanedial), succinaldehyde (butanedial), terephthalaldehyde, 1,2,3,4-diepoxybutane, 1,2:5,6-diepoxyhexane, 1,2:7,8-diepoxyoctane, epoxy resins such as bisphenol A diglycidyl ether and epoxyphenol novolac, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, tartaric acid, citric acid, terephthalic acid, phthalic acid, aspartic acid, glutamic acid, maleic anhydride, succinic anhydride, and phthalic anhydride.

[0133] In one embodiment, viscosity modifiers may be employed in the photosensitive composition, such as surfactants or surface-active materials, which may be used in addition to or in addition to the water-soluble or dispersible polymers.

[0134] In one embodiment, the photosensitive composition may contain at least one hydrogen bond-forming additive capable of forming hydrogen bonds with the binder, selected from the group consisting of alcohols, ketones, aldehydes, amines, amides, amino acids, carboxylic acids, thioethers, thiols, urethanes, esters, lactones, lactams, and any desired combination thereof. Preferably, the hydrogen bond-forming additive is selected from the group consisting of polyols, polyamines, polyethers, polyesters, polyamides, and anionic polymers such as ionic polymers, e.g., polystyrene sulfonic acid. Particularly preferred hydrogen bond-forming additives are polyethyleneimine and polyurethanes containing ethylene glycol units. In one embodiment, polyurethane acrylate PUA BIN 200 available from BASF, polyethylene glycols such as PEG-400 and PEG-2000, polyvinyl alcohol / polyethylene glycol graft copolymers such as Alcotex 97-5, and any desired combination thereof are preferred. In a specific embodiment, the hydrogen bond-forming additive is a polyvinyl alcohol / polyethylene glycol graft copolymer. The hydrogen bond forming additive is generally present in an amount of 1 to 30 wt%, preferably 1 to 25 wt%, more preferably 5 to 20 wt%, and most preferably 10 to 20 wt%, based on the total formulation.

[0135] Developable Relief Precursor (RP) 1 shows a schematic representation of a developable relief precursor RP comprising a dimensionally stable carrier layer L1, at least one photosensitive layer L2, and optionally one or more additional layers, such as an optional layer OL and a laser ablatable mask layer ML. Layer L2 comprises a photosensitive composition of the present invention as described herein and may have components with corresponding properties as described above. By configuring a photosensitive composition as described herein in this manner, one or more of the advantages as described above can be achieved.

[0136] In a preferred aspect of the present invention, the relief precursor has an AOX value of less than 3.2 mg / L, preferably less than 3 mg / L, more preferably less than 2.8 mg / L, and even more preferably less than 2.6 mg / L. The AOX value is determined according to the method as described in Example 2 herein. These desired values ​​are achieved by the incorporation of a photosensitive composition.

[0137] By incorporating the photosensitive composition of the present invention into the relief precursor, isolated dot profiles with diameters of 100 μm or less are possible. This can improve the resolution of printed images. Furthermore, it is believed that the ionic groups in the photosensitive composition enhance the relief-forming reaction in layer L2, so that the resulting relief structure achieves a printing result that approaches a one-to-one image transfer from the source image to the print. Therefore, improved printing predictability and accuracy are achieved. The compositions described herein improve the identity of the resulting printed areas with, for example, patterns created using transparent regions on a photographic mask or patterns created on a laser-ablatable mask layer.

[0138] FIG. 2 illustrates the principle of relief precursor development, as further described herein. In FIG. 2A, a cross section of the relief precursor RP is shown after removal of the cover layer CL and partial ablation of the mask layer ML as a result of an image transfer process controlled, for example, by an energy source 1 as shown in FIG. 2A. Preferably, this energy source is a laser, and a laser beam 11 ablates the mask layer ML, creating open areas 32 as shown in FIG. 2A. Additionally or alternatively, the mask layer can have its absorption and / or reflection properties modified to make it at least partially transparent to the electromagnetic radiation used during exposure of the relief precursor. The mask layer may further comprise additional components, such as binders and additives to ensure effective processability, film formation, and development. The mask layer is preferably a laser-ablatable mask layer ML that can be ablated by laser radiation 1 as a result of a high energy input 11, for example, as shown in FIG. 2A. Laser ablation occurs only at locations 32 where the laser beam 11 is or was directed at the mask layer. In this way, an image or pattern is created in the mask layer, which can later form an equal or similar image or pattern on the resulting relief structure. Subsequent exposure of the photosensitive layer L2 to electromagnetic radiation 2, e.g., as shown in Figure 2A, in exposed areas 22 causes crosslinking and / or polymerization reactions in layer L2. Thereafter, as shown by the dashed lines in Figure 2B, the mask layer ML and the unexposed material of the photosensitive layer L2 are removed, thereby creating a relief structure RS having a hardened and / or polymerized relief 23 thereon.

[0139] FIG. 3 illustrates the improved one-to-one ratio, which can be better understood by comparing FIG. 3, particularly FIG. 3A and FIG. 3B, in which a relief structure RS1 made with a typical photosensitive composition is shown in FIG. 3A and a relief structure RS2 made with a photosensitive composition as described herein is shown in FIG. 3B. The relief 36 shown in FIG. 3B is more equivalent to the ablated pattern 32 on the mask layer ML, and therefore the printed area or printed pattern 31 on the printing substrate PS is more equivalent to the original pattern 32 created on the mask layer ML. A photographic mask may be used instead of the mask layer ML. Because of the improved one-to-one ratio, the printed image 31 on the printing substrate PS is more equivalent to the original ablated pattern 32 on the mask layer ML, and therefore, more predictable results are achieved, especially when compared to the printed pattern 30 printed using a relief 35 containing a typical photosensitive composition. Such a typical relief structure RS1 typically exhibits deviations between the original pattern OL and the printed pattern PP. FIG. 3A illustrates a case where deviations cause the transferred printed image 30 to be smaller than the original ablated pattern 32 .

[0140] [Dimensionally stable carrier layer L1] Preferably, the carrier layer L1 comprises a metal sheet, steel, an alloy, a natural or artificial polymer, a polymer blend, a polymer film, or any combination thereof. Examples of suitable dimensionally stable carriers include plates, foils, and conical and cylindrical tubes, also known as sleeves, made of metals such as steel, aluminum, copper, or nickel; plastics such as polyethylene terephthalate, polybutylene terephthalate, polyamide, or polycarbonate; woven or nonwoven fabrics such as glass fiber fabrics; or composite materials composed of glass fiber and plastic. Particularly suitable dimensionally stable carriers are dimensionally stable carrier foils or metal sheets, such as polyethylene or polyester foils, or steel or aluminum sheets. The carrier foils or metal sheets generally have a thickness of 50 to 1500 μm, preferably 75 to 400 μm, e.g., about 250 μm. When steel is used as the carrier material, a steel sheet having a thickness of 0.05 to 0.3 mm is preferred. For corrosion protection, tin-plated steel sheets are preferred. These carrier foils or sheets may be coated with a thin adhesion-promoting layer, for example a layer having a thickness of 0.1 μm to 2 μm, on the side of the carrier foil facing the radiation-curable relief-forming layer. In a preferred embodiment, the carrier layer is a PET carrier layer made of polyethylene terephthalate.

[0141] [Photosensitive layer L2] Typically, at least the photosensitive layer L2 contains the photosensitive composition described herein. Preferably, the photosensitive layer L2 has a thickness ranging from 25 μm to 5000 μm, preferably from 0.01 to 4 mm, more preferably from 0.02 to 3 mm, and most preferably from 0.03 mm to 3 mm. The photosensitive layer may contain various sublayers containing the components described above for the photosensitive composition, but the raw materials may be present in different concentrations and / or as different components. For example, one sublayer may contain only nonionic monomers, while another sublayer contains an ethylenically unsaturated compound with an ionic group. In this manner, a photosensitive layer can be designed with desired properties at specific locations or heights within the photosensitive layer. For example, a sublayer can be designed to contain component E in a higher concentration than another sublayer. The other sublayers may be located above or below a sublayer with a higher concentration of component E. It should be understood that the term "above" is interpreted as being closer to the surface of the printing plate and therefore farther away from the dimensionally stable carrier layer.

[0142] One or more additional layers An optional additional layer OL may be disposed between layers L1 and L2, on top of L2, or both. Preferred examples of additional layers include a barrier layer, a laser ablatable mask layer, an adhesive layer, a release or release layer, a UV / VIS light and / or IR light absorbing layer, a monomer diffusion control layer, a surface control layer, a protective layer, a cover foil, a cover film, or a combination thereof.

[0143] In one embodiment, an adhesive coating layer may be present, with an optional top coating layer thereon. Such an adhesive coating layer may be, for example, a layer of polyurethane adhesive coating material, as described in DE 3045516. Such adhesive coating material may be based on a polyisocyanate-crosslinked polyether or polyester coating material. The adhesive coating layer with the optional top coating layer may have a thickness of between 0.5 and 50 μm, more particularly between 2 and 30 μm. The top coating layer may be located on the surface of the adhesive coating layer opposite the carrier layer and generally has a layer thickness of between 0.1 and 50 μm, more particularly between 1 and 10 μm. For example, it may be obtained by applying a dilute aqueous alcoholic solution of partially hydrolyzed (e.g., to about 80% hydrolysis) polyvinyl ester, phenylglycerol ether monoacrylate (2-hydroxy-3-phenoxypropyl acrylate), and glyoxal, followed by drying and baking the top coating layer. The adhesion between the dimensionally stable carrier layer and the photosensitive layer in the exposed or unexposed state should be greater than 0.5 N / cm as measured in a peel test at a peel angle of 90° and a peel rate of 30 mm / min.

[0144] For example, as shown in FIG. 1, a barrier layer OL or protective layer and / or cover layer CL may be present in the relief precursor RP to protect the photosensitive layer L2, also referred to as the radiation-curable and / or relief-forming layer. Typically, these layers provide protection from environmental influences, such as light, moisture, oxygen, or ozone. Additional or similar barrier layers may also be present to protect the photosensitive layer from contamination and / or damage during storage or handling. However, it is also possible to integrate different barrier layers with different properties into a single layer. The barrier layer may be a separate barrier layer or may be similar or equivalent to a carrier layer with corresponding barrier properties. The protective foil or barrier layer may consist of a plastic that absorbs and / or reflects the corresponding wavelengths; for example, polyethylene naphthalate absorbs in the UV range; EP 0 504 824 and EP 0 767 406 describe other materials suitable for protective barrier layers. A moisture barrier layer may also be present, preferably consisting of a polymer exhibiting a low diffusion coefficient for water, such as polyethylene, polypropylene, polyester, and polyvinyl alcohol.

[0145] An oxygen barrier layer (OL) is preferably present because the free radical polymerization reaction that forms polymer chains and / or polymer networks upon exposure to light is affected by the presence of oxygen. Growing polymer chains can react with molecular oxygen, generating oxygen radicals that can slow their propagation rate. Suitable materials for the oxygen barrier layer include both water-soluble and organic solvent-soluble binders, such as polyamides, polyvinyl alcohols, hydroxyalkyl celluloses, ethylene-vinyl acetate copolymers, amphoteric interpolymers, cellulose acetate butyrate, alkyl celluloses, butyrals, cyclic rubbers, and combinations thereof. Polyvinyl alcohols, partially hydrolyzed and highly hydrolyzed polyvinyl carboxylates, poly(ethylene oxide-vinyl alcohol) graft copolymers, or poly(ethylene vinyl alcohol) copolymers are preferred. The barrier layer generally has a thickness of 0.2 μm to 10 μm, preferably 0.3 to 8 μm.

[0146] Typically, the barrier layer OL is positioned in direct contact with the photosensitive or radiation-curable layer L1 to prevent undesirable low-molecular-weight substances or impurities from migrating, diffusing, or transferring from the environment into the photosensitive layer. These impurities may be, for example, moisture, oxygen, ozone, or a combination thereof. Additionally or alternatively, these impurities may originate from another layer, such as a dye or UV absorber. The same or another layer may also prevent low-molecular-weight substances, such as initiators or monomers, from diffusing from the photosensitive layer to a nearby layer, such as an upper layer. Other configurations, such as disposing the barrier layer at a different location or employing two or more barrier layers, are also possible. Suitable barrier layers for moisture, light, and oxygen are those described above. The diffusion-preventing barrier layer has high diffusion resistance to migrating substances, such as initiators and monomers. Generally speaking, the barrier layer is at least partially water-soluble or water-dispersible.

[0147] Adhesion layers may be present to enhance the adhesion between the individual layers and stabilize the layer structure, such layers comprising substances that interact with both boundary layers, such as surfactants, amphiphilic molecules with hydrophobic and hydrophilic regions, block copolymers, oligomers containing blocks that are compatible with the polymers of the two or boundary layers.

[0148] One or more release layers may be present to reduce adhesion between individual layers and facilitate removal of another layer, e.g., by peeling. For example, a release layer may facilitate removal of a protective foil. These layers may be located in any of a wide variety of different positions in the layer configuration and may be used to facilitate removal of one or more layers.

[0149] In one embodiment, a surface structure-generating layer may be present, which is designed to generate a surface structure on the radiation-curable layer. This layer is usually placed in direct contact with the radiation-curable layer and is designed to influence the structure or roughness of the surface of said layer. Such a layer can be applied by embossing or impressing during the manufacture of the layered assembly that forms the relief precursor.

[0150] In one embodiment, the mask layer ML allows imagewise exposure of the radiation-curable layer L2 and includes at least one material that absorbs and / or reflects the electromagnetic radiation used during exposure of the relief precursor. Additionally, the mask layer includes a material that allows localized removal of the mask layer ML as a result of an image transfer process controlled by, for example, an energy source 1, as shown in FIG. 2A. Preferably, this energy source is a laser, and a laser beam 11 ablates the mask layer ML, creating, for example, open areas 32, as shown in FIG. 2A. Additionally or alternatively, the mask layer can have its absorption and / or reflection properties modified to make it at least partially transparent to the electromagnetic radiation used during exposure of the relief precursor. The mask layer may further include additional components, such as binders and additives that ensure effective processability, film formation, and development. The mask layer is preferably a laser-ablatable mask layer ML that can be removed by laser radiation 1 as a result of high energy input 11, as shown in FIG. 2A. Laser ablation occurs only at positions 32 where the laser beam 11 is or was directed at the mask layer. Thus, an image or pattern is created in the mask layer, which can later form an identical or similar image or pattern on the resulting relief structure. Subsequent exposures to electromagnetic radiation 2, e.g., as shown in FIG. 2A, in the exposed areas 22 of the photosensitive layer L2 induce crosslinking and / or polymerization reactions in the layer L2. Subsequently, as shown by the dashed lines in FIG. 2B, the mask layer ML and the unexposed material of the photosensitive layer L2 are removed, thereby creating a relief structure RS with a hardened and / or polymerized relief 23 thereon. The mask layer is preferably ablated using an infrared laser with a wavelength in the range of 700 nm or greater, preferably 750 nm to 1 mm. Subsequent exposures are then performed using electromagnetic radiation in the UV range. Pre-exposure and post-exposure cycles can be applied. Suitable laser ablatable mask layers are described, for example, in WO 9403839, US Pat. No. 5,262,275, WO 9403838, and EP 0767406.Laser-ablatable mask layers generally contain one or more water-soluble or water-dispersible binders, or binders soluble or dispersible in aqueous / alcoholic solvent mixtures, and materials that absorb IR light or exhibit strong absorption in the wavelength range of 750-20,000 nm, preferably 750-5,000 nm. The mask layer may contain a plasticizer. IR-sensitive mask layers have an optical density of 2.5 or greater, preferably between 3 and 5, for actinic light. Examples of binders suitable for the mask layer include partially hydrolyzed polyvinyl esters, such as partially hydrolyzed polyvinyl acetate; polyvinyl alcohol derivatives, such as partially hydrolyzed vinyl acetate / alkylene oxide graft copolymers; maleic anhydride copolymers, such as copolymers of maleic anhydride and isobutene or maleic anhydride and vinyl methyl ether; water-soluble polyesters; water-soluble polyethers; vinyl pyrrolidone; vinyl caprolactam; vinyl imidazole; vinyl acetate; acrylamide; water-soluble polyurethanes; homopolymers and copolymers of polyamides soluble in water or water-alcohol mixtures; or mixtures of these polymers. The IR-absorbing material used may include dyes and / or pigments. Examples of dyes that can be used include phthalocyanine and substituted phthalocyanine derivatives, cyanine and merocyanine dyes, or polymethine dyes. Examples of pigments that can be used include carbon black, graphite, chromium oxide, or iron oxide.

[0151] The IR-absorbing material in the ML is typically present in a weight concentration of 1 to 60 wt %, based on the total weight of the mask layer. Any compound that absorbs UV light can be used to render the IR-sensitive mask layer opaque to actinic light. Examples are the dyes and pigments mentioned above. Many initiators in the photosensitive layer are sensitive to UV light. As a result, carbon black is frequently used as a pigment in the IR-sensitive layer. When carbon black is used as a pigment in the IR-sensitive layer, the use of an additional IR-absorbing material is unnecessary. The concentration of the actinic light-opaque material is selected to obtain the required optical density. Typically, the required optical density is greater than 2.5. When carbon black is used as a pigment in the IR-sensitive layer, its amount is approximately 1 to 60 wt %, preferably 1 to 40 wt %, based on the total weight of the IR-sensitive mask layer.

[0152] As the outermost layer, the relief precursor generally comprises a protective layer, cover layer, or cover foil CL, preferably a protective foil or film, which protects the radiation-curable layer from mechanical damage caused, for example, by scratches, dirt, or dust. This protective layer is typically removed before further processing steps. Generally, the protective layer is a thin, preferably similarly dimensionally stable polymer foil made of polyester, such as polyethylene terephthalate or polybutylene terephthalate, polyamide, polyurethane, or polyethylene. To protect the radiation-curable layer from light, the protective layer can also comprise a light-absorbing material, thus preventing premature and unwanted polymerization of the radiation-curable layer.

[0153] Methods for Preparing Developable Relief Precursors (RP) Further according to the present invention, there is provided a method for producing a developable relief precursor, the method comprising the steps of providing at least one dimensionally stable carrier layer; optionally providing an adhesive layer and / or adhesive treatment on the dimensionally stable carrier layer; providing a photosensitive composition on the at least one dimensionally stable carrier layer; and optionally providing one or more additional layers and / or treatments, wherein the photosensitive composition is an inventive photosensitive composition according to the present invention as described herein and may have components with corresponding properties as described above. An exemplary embodiment of the produced relief precursor RP is shown in Figure 1.

[0154] In more detail, the method can be generally described as follows: a) providing a carrier layer L1, e.g. b) optionally washing the support; c) optionally applying one or more optional layers OL; d) applying at least one layer of a photosensitive composition L2; e) optionally further processing the layered assembly, preferably by drying; f) optionally applying one or more optional layers OL; g) optionally further processing the layer configuration; Includes.

[0155] In step a), a dimensionally stable carrier is provided, which may be further provided with optional layers (eg, adhesion promoter layers, barrier layers, coating layers).

[0156] In optional step b), the surface of the carrier is cleaned and optionally coated with any layer or directly with the photosensitive composition. The cleaning operation is intended to remove, in particular, dust and foreign particles, as well as surface stains of a type that adversely affect adhesion (e.g., fingerprints). Any method familiar to those skilled in the art can be used here, such as brushing, blowing, wiping (with or without solvent), rinsing, and any desired combination thereof. Generally speaking, such cleaning is carried out.

[0157] In optional step c), one or more optional layers can be applied, such as an adhesion promoter layer or intermediate layer, a barrier layer or a coating layer, or a suitable combination of these layers. The optional layers can be applied by any method well known to those skilled in the art, such as calendering, lamination, extrusion, casting, dipping, spraying, coating or lining, or a suitable combination thereof. Preferably, in step c), a carrier foil or carrier sheet is coated with an adhesive layer and baked or dried. It is also possible to use a carrier film, preferably a polyethylene terephthalate, polybutylene terephthalate, polyamide and / or polycarbonate carrier film, coated with an adhesion promoter layer.

[0158] In step d), at least one layer of a photosensitive composition is applied; between the application of two or more layers, other operational steps may be performed, such as drying, irradiation, or spraying, and suitable combinations thereof. The photosensitive composition may be applied by any method well known to those skilled in the art, such as laminating, lining, casting, dipping, spraying, and suitable combinations thereof. It may be possible to heat or cool the photosensitive composition and / or layer. Depending on the application method in step d), it may be necessary to carry out further processing of the layer structure in step e). In particular, when a liquid mixture or a solvent-containing mixture is applied, it may be preferable to carry out a drying step by heating the layer assembly or evaporating the solvent under reduced pressure, for example, at 1 atmosphere. It may also be possible to subject the layer structure to mechanical processing, for example, by rolling or pressing. Furthermore, it may be advantageous at this stage to irradiate the layer structure with electromagnetic waves from at least one side that is appropriately transparent.

[0159] The photosensitive composition is applied by casting onto a preferably dimensionally stable metal sheet, more particularly made of aluminum or steel, comprising, for example, one top coating layer consisting of a dilute aqueous / alcoholic solution of partially hydrolyzed polyvinyl ester, phenylglycerol ether monoacrylate, and glyoxal, or onto a dimensionally stable foil, preferably made of PET, having an adhesive layer consisting of a polyurethane adhesive coating material based on a polyisocyanate-crosslinked polyether or polyester coating material, for example according to DE-A-3045516, and heating the applied mixture to dryness at 50-200°C in a drying tunnel.

[0160] The thickness of the applied and optionally treated photosensitive radiation curable layer is generally from 0.01 to 5 mm, preferably from 0.01 to 4 mm, more preferably from 0.02 to 3 mm, and most preferably from 0.03 mm to 3 mm.

[0161] In optional step f), one or more additional layers may be applied to the radiation-curable relief-forming layer. Such layers may include protective layers, barrier layers, mask layers, adhesive layers, release layers, layers for generating surface structures, and suitable combinations of these layers. The optional layer or layers may be applied by any method well known to those skilled in the art, such as calendaring, lining, laminating, rolling, extruding, casting, dipping, spraying, and suitable combinations thereof. Here too, further processing of the layer structure may be required. In particular, when applying a liquid or solvent-containing mixture, a drying step may be required, such as heating the layer assembly or evaporating the solvent under reduced pressure. Generally speaking, at least one protective layer, preferably a protective foil, is applied, preferably by laminating or lining.

[0162] In one embodiment, the photosensitive composition may be applied, for example, by casting, to a carrier foil or protective foil, dried, and then laminated to a metallic or polymeric carrier, in which case a solvent may also be employed. It is also possible to apply the photosensitive composition to a carrier, apply any layers to a foil, and then laminate the foil with any layers to the photosensitive composition. If either the layer or the radiation-curable mixture was heated in a previous step, it may be advantageous to perform active cooling of the formed layer structure. Optionally, the layer structure in step g) may be subjected to further treatments advantageous for further processing, such as exposure to electromagnetic waves that are appropriately transparent on at least one of the two sides of the layer structure, optical quality control for defects and / or impurities, cutting to a predetermined format, heat treatment, packaging, storage, and any desired combination thereof. Optionally, the one or more treatments are selected from the group including surface treatments, adhesive treatments, corona treatments, flame treatments, chemical treatments, plasma treatments, top coating treatments, or combinations thereof.

[0163] [Method for manufacturing the relief structure (RS)] The method comprises the steps of providing a relief precursor comprising the inventive photosensitive composition according to the present invention as described herein; exposing the photosensitive composition to electromagnetic radiation, preferably imagewise; and removing the unexposed areas with the aid of a developer.

[0164] Preferably, the exposing step is performed through an ablated mask layer, for example as shown in Figure 2A, and / or through a mask disposed between the photosensitive layer L2 and the electromagnetic radiation source 2. In general, the method comprises: a) providing a relief precursor comprising a photosensitive composition as described herein; b) optionally washing the relief precursor; c) optionally applying electromagnetic radiation from the first side; d) optionally removing a protective layer, e.g. a cover layer; e) optionally applying a mask; f) transferring an image into the mask layer, for example by using laser ablation; g) irradiating the electromagnetic radiation through the ablatable mask layer and / or irradiating the electromagnetic radiation through the mask, e.g., through openings in the mask layer; h) optionally removing the mask layer; i) removing non-irradiated areas; j) optionally performing further processing; Includes.

[0165] In a first step a), the relief precursor described is provided, which may optionally be cleaned in step b), using any method familiar to those skilled in the art, such as brushing, blowing, wiping (with or without solvent), rinsing, and any desired combination thereof.

[0166] In optional step c), the relief precursor is extensively irradiated from at least one side with electromagnetic radiation (see above). This irradiation is preferably carried out from the side of the radiation-curable layer opposite the mask layer (back exposure) in order to achieve fixation of the relief structure to be generated. This back exposure is preferably carried out through a transparent, dimensionally stable material, such as a polymer film, especially a polyester film, as a carrier material.

[0167] If a protective layer is present, it may be removed in optional step d), which can be done mechanically or chemically by treatment with solvents, water and aqueous solutions. The protective layer is preferably a protective film or foil and is peeled off.

[0168] If the relief precursor does not contain a mask layer, this mask layer can be applied in optional step e).Here, the mask layer may already have been image-transferred, in which case step f) is omitted.The mask can be or be a mask layer, and can be applied by any method known to those skilled in the art, such as placing, calendaring, laminating, rolling, extruding, casting, dipping, spraying, lining, and suitable combinations thereof.Optionally, especially when applying a liquid formulation, further processing steps may be required, such as drying, rolling, and / or cooling.The mask layer is preferably placed or laminated on the relief precursor.

[0169] The order of steps b), c), d) and e) may be suitably changed.

[0170] In step f), an image is transferred to the mask layer, which is optional only if an image-transferred mask layer is applied in step e) or if the radiation-sensitive layer is directly exposed, for example, by spatially resolved projection of a stimulating laser beam or electromagnetic radiation. The image is transferred to the mask layer either by layer removal and / or spatially resolved change of absorption and / or reflection properties, so that the mask layer becomes at least partially transparent in the wavelength range used for image transfer. It is preferred to use a mask layer that can be ablatable by an IR laser.

[0171] In step g), the relief precursor is irradiated with electromagnetic radiation from the radiation-sensitive layer opposite the dimensionally stable material, initiating the radiation-induced polymerization and crosslinking reaction. If an image-transferred mask is present, irradiation can be carried out over a wide area, or, if operating without a mask layer, irradiation can be carried out by image-transferring small areas (essentially point-like) using a stimulating laser beam or spatially resolved projection of electromagnetic radiation. The wavelength of the irradiated electromagnetic radiation in this case is in the range of 200 to 2000 nm, preferably in the range of 200 to 450 nm, and more preferably in the range of 250 to 405 nm. Irradiation can be continuous or pulsed, or can involve multiple short-term successive irradiations. In addition to broadband electromagnetic radiation, it can be advantageous to use narrowband or monochromatic wavelength ranges, such as can be generated using appropriate filters, lasers, or light-emitting diodes (LEDs). In such cases, wavelengths in the ranges of 350, 365, 385, 395, 400, 405, 532, 830, and 1064 nm (and about 5-10 nm above and below) are preferred, individually or in combination. The radiation intensity here may be varied over a wide range to ensure that a sufficient dose is used to sufficiently harden the radiation-curable layer for the subsequent development procedure. The radiation-induced reaction must proceed sufficiently so that, optionally after further thermal treatment, the exposed areas of the radiation-sensitive layer become at least partially insoluble and therefore cannot be removed in the development step. The radiation intensity and dose depend on the reactivity of the formulation and the duration and efficiency of development. The radiation intensity should be between 1 and 15,000 mW / cm. 2in the range of 5 to 5000 mW / cm 2 in the range of 10 to 1000 mW / cm 2 The radiation dose ranges from 0.3 to 6000 J / cm 2 in the range of 3 to 100 J / cm 2 in the range of 6 to 20 J / cm 2 The exposure to the energy source can also be carried out in an inert atmosphere, such as a noble gas, CO2 and / or nitrogen, or under a liquid that does not damage the relief precursor.

[0172] In step h), the mask layer can be optionally removed, which can be done mechanically or chemically by treatment with solvents, water and aqueous solutions. Removing the mask layer individually is particularly suitable when the layer can be mechanically peeled off as a whole, or when the mask layer is simply placed or laminated. If operating without a mask layer, this step is not necessary.

[0173] To generate a relief structure, the areas of the radiation-curable layer not exposed in step g) are removed in step i). Any method known to those skilled in the art can be used in this development step. Irradiation induces polymerization and / or crosslinking in the radiation-curable layer, reducing its solubility. To remove the unexposed areas, a solvent, water, and / or an aqueous solution, or a combination thereof, is preferably used as the developer. The solvent and aqueous solution may contain an auxiliary agent that stabilizes the formulation and / or increases the solubility of the components of the radiation-curable layer. Examples of such auxiliary agents are emulsifiers, surfactants, salts, acids, bases, stabilizers, corrosion inhibitors, and suitable combinations thereof. Development with these solutions can be carried out using any method known to those skilled in the art, such as immersion, washing, or spraying with the development medium, brushing in the presence of the development medium, and suitable combinations thereof. Development is preferably carried out using a neutral aqueous solution or water, with the aid of a brush or a plush web for removal. Another way to influence development is to control the temperature of the development medium, for example, to accelerate development by increasing the temperature. In this step, any layers still present on the radiation-sensitive layer can be removed if they can be detached during development and sufficiently dissolved and / or dispersed in the development medium.

[0174] After the preceding step, an optional further processing step (step j) can be performed. This includes, for example, heat treatment, drying, treatment with electromagnetic radiation, attaching an identification feature, trimming, coating, and any desired combination thereof. For example, heat treatment can be used to initiate and / or complete the reaction, improve the mechanical and / or thermal integrity of the relief structure, and remove volatile components. Known methods can be used for heat treatment, such as heating with a heated gas or liquid, IR radiation, and any combination thereof. Here, ovens, fans, lamps, and any desired combination thereof can be employed. For example, additional treatment with electromagnetic radiation can be used to induce and / or complete polymerization and / or crosslinking reactions, to render the surface of the relief structure non-tacky. In this case, the wavelength of the irradiated electromagnetic waves is in the range of 200 to 2000 nm, as already described above.

[0175] By including the photosensitive composition of the present invention in the relief precursor used in the method for producing a relief structure, fewer chemicals migrate into the developer, resulting in a developer having an AOX value of 3.2 mg / L or less, preferably less than 3 mg / L, more preferably 2.8 mg / L or less, and most preferably 2.6 mg / L or less, as determined according to the method described in Example 2 herein.

[0176] Methods according to the present invention typically involve a rinse time of 4 minutes or less, preferably 3.5 minutes or less, most preferably 3 minutes or less.

[0177] Another method of producing a relief structure involves irradiating a relief-forming layer and imprinting a relief in the radiation-hardened areas of the relief-forming layer. Such a method appears to be particularly suitable for forming pad printing plates. Very generally, this method involves: a) providing a relief precursor; b) optionally washing the relief precursor; c) optionally irradiating the backside with electromagnetic radiation; d) optionally removing the protective layer; e) exposing the radiation curable layer to electromagnetic radiation; f) imagewise ablating at least a portion of the radiation curable layer; g) optionally performing further processing; Includes.

[0178] In a first step a), a relief precursor is provided, which may optionally be cleaned in step b), by any method well known to those skilled in the art, such as brushing, blowing, wiping (with or without solvent), rinsing, and any desired combination thereof.

[0179] In optional step c), if the back side of the relief precursor is transparent to the wavelength used, the relief precursor can be extensively irradiated with electromagnetic radiation from the back side. This irradiation is advantageously carried out from the side of the radiation-sensitive layer opposite the mask layer in order to achieve fixation of the relief structure to be generated (backside exposure). This backside exposure is preferably carried out through a transparent, dimensionally stable material, such as a polymer film, in particular a polyester film. Here, the wavelength of the irradiated electromagnetic radiation is in the range of 200 to 2000 nm, as already mentioned above.

[0180] If a protective layer is present, it may be removed in optional step d), which can be done mechanically or chemically by treatment with solvents, water and aqueous solutions. The protective layer is preferably peeled off.

[0181] The order of steps b), c), and d) can be changed as desired. In step e), the layer structure is irradiated with electromagnetic radiation from the side of the radiation-sensitive layer opposite the dimensionally stable material, initiating the radiation-induced reaction. Irradiation can be broad-based or can be performed by image transfer in small areas (essentially point-like) using a stimulating laser beam or electromagnetic radiation projection. The wavelength of the electromagnetic radiation irradiated in this case is in the range of 200 to 2000 nm, as already described above. Irradiation can be continuous or pulsed, or multiple short-term successive irradiations can be performed. The radiation intensity here can be varied over a wide range to ensure that a sufficient dose is used to sufficiently transform the radiation-sensitive layer for subsequent use. The radiation-induced reaction must proceed sufficiently to stabilize the exposed areas of the radiation-sensitive layer, possibly after further heat treatment. The radiation intensity and dose depend on the reactivity of the formulation and the aggressiveness of development. The radiation intensity is 1 to 15,000 mW / cm. 2 in the range of 5 to 5000 mW / cm 2 in the range of 10 to 1000 mW / cm 2 The radiation dose ranges from 0.3 to 6000 J / cm 2 in the range of 3 to 100 J / cm 2 in the range of 6 to 20 J / cm 2The exposure to the energy source can also be carried out in an inert atmosphere, such as a noble gas, CO2 and / or nitrogen, or in a liquid that does not damage the relief precursor. The relief structure is completed in step f) by imagewise ablation of at least a portion of the radiation-sensitive layer. This can be done by mechanical methods or ablation with high-energy radiation. In the case of mechanical methods, specific areas of the radiation-sensitive layer are removed with at least one tool, thereby achieving image transfer. The tool can be controlled using a computer-aided process. In the case of ablation with high-energy radiation, a beam is guided onto the radiation-sensitive layer with computer assistance, removing material in the exposed areas. In this case, the wavelength of the irradiated electromagnetic wave is in the range of 500 nm to 100 μm, preferably in the IR range, particularly preferably in the range of 500 nm to 50 μm, and very particularly preferably in the range of 800 nm to 20 μm. In addition to broadband electromagnetic radiation, it may be advantageous to use narrowband or monochromatic wavelength ranges of the kind that can be produced using low-pressure lamps, high-pressure lamps, fluorescent lamps and / or flash lamps equipped with corresponding filters, lasers or light-emitting diodes (LEDs). In these cases, wavelengths in the range of 830 nm, 980 nm, 1064 nm and 10.6 μm are preferred, individually or in combination. It is preferred to use LEDs and fluorescent lamps or fluorescent tubes, optionally in combination with each other.

[0182] The relief depth achievable in this process is limited by the thickness of the applied radiation-sensitive layer and is in the range of 10 to 1000 μm, preferably 20 to 500 μm, and particularly preferably 30 to 100 μm. The preceding step can optionally be followed by a further processing step (step j). This includes, for example, heat treatment, drying, treatment with electromagnetic radiation, attachment of an identifying feature, trimming, coating, and any desired combination thereof. For example, heat treatment may be used to initiate and / or complete the reaction, to improve the mechanical and / or thermal integrity of the relief structure, and to remove volatile components. Known methods can be used for heat treatment, such as heating with heated gases or liquids, IR radiation, and any combination thereof. Ovens, fans, lamps, and any desired combinations thereof can be used here.

[0183] For example, treatment with electromagnetic radiation may be used to induce and / or complete polymerization and / or crosslinking reactions in order to render the surface of the relief structure non-sticky, in which case the wavelength of the irradiated electromagnetic waves is in the range of 200 to 2000 nm, as already explained above. [Item 1] 1. A developable relief precursor photosensitive composition comprising: at least one ethylenically unsaturated monomer as component E; at least one photoinitiator or photoinitiator system as component P; at least one water-soluble and / or water-dispersible binder as component B; optionally one or more additives as component A, Component E contains at least one ionic group; A photosensitive composition, wherein component E is present in an amount of 0.1 to 30 wt %, based on the total weight of the photosensitive composition. [Item 2] Item 2. The photosensitive composition of item 1, wherein component E is present in an amount of 0.5 to 20 wt %, based on the total weight of the photosensitive composition. [Item 3] 3. The photosensitive composition according to item 1 or 2, wherein component E has a solubility in water of pH 7 at 20°C and 1 atmosphere of 200 g / L or more, preferably in the range of 500 to 1500 g / L. [Item 4] 4. The photosensitive composition according to any one of items 1 to 3, wherein component E has a molecular weight in the range of 100 to 1000 g / mol. [Item 5] 5. The photosensitive composition of any one of items 1 to 4, wherein component E comprises at least one of an acrylate group, a methacrylate group, an acrylamide group, a vinyl group, a vinyl ether group, or a combination thereof. [Item 6] Component E has a vapor pressure, and the vapor pressure is less than 50 hPa at 25°C; 6. The photosensitive composition according to any one of items 1 to 5, wherein the vapor pressure is determined in accordance with the "ASTM E1194-17" standard for vapor pressures less than 1 Pa, and in accordance with the "ASTM D2879-18" standard for vapor pressures of 1 Pa or more. [Item 7] 7. The photosensitive composition according to any one of items 1 to 6, wherein component E has an AOX value of less than 2600 mg / L, preferably less than 1000 mg / L, more preferably less than 100 mg / L, and wherein the AOX value is determined according to the method as described in Example 1. [Item 8] 8. The photosensitive composition according to any one of items 1 to 7, wherein the at least one ionic group contained in component E is selected from the group consisting of a quaternary ammonium group, a carboxylate group, a sulfonate group, a sulfonium group, a phosphonium group, and combinations thereof. [Item 9] 9. The photosensitive composition of any one of items 1 to 8, wherein component E is a quaternized amino-functional monomer. [Item 10] 10. The photosensitive composition according to any one of items 1 to 9, further comprising an ethylenically unsaturated compound as a component EM, wherein the component EM does not have an ionic group. [Item 11] 11. The photosensitive composition according to item 10, wherein component EM is present in an amount of 0.5 to 50 wt %, based on the total weight of the photosensitive composition, and the ratio of EM / E is between 0.1 and 10, more preferably between 0.15 and 8, and even more preferably between 0.2 and 5. [Item 12] 12. The photosensitive composition according to any one of items 1 to 11, wherein component P is selected from the group comprising benzil ketals, hydroxyketones, aminoketones, acylphosphine oxides, bisacylphosphine oxides, thioxanthones, anthraquinones, coumarins, hexaarylbisimidazoles, benzophenones, and combinations thereof. [Item 13] Item 10. The photosensitive composition of item 1, wherein component P is a photoinitiator system further comprising a coinitiator, wherein the coinitiator is selected from the group consisting of amines, thiols, thioethers, aminoalcohols, thioetheramines, and combinations thereof. [Item 14] Component B is Polyvinyl alcohol, polyvinyl acetate, partially hydrolyzed polyvinyl acetate, functionalized polyvinyl alcohol, Functionalized polyvinyl acetate, functionalized partially hydrolyzed polyvinyl acetate, Polyvinyl acetal, Copolymers of polyvinyl acetate and at least one other monomer, a polyvinyl acetate polymer or copolymer having at least one grafted unit; Polyurethane, polyacrylate, polyamide, polyether or a combination thereof. [Item 15] the functionalized polyvinyl alcohol and / or the functionalized partially hydrolyzed or non-hydrolyzed polyvinyl acetate is functionalized with an ethylenically unsaturated group; and / or the at least one other monomer in the copolymer of polyvinyl acetate is ethylene; and / or the at least one grafted unit of the polyvinyl acetate polymer or copolymer is polyethylene glycol; Item 15. The photosensitive composition according to item 14. [Item 16] 16. The photosensitive composition of any one of items 1 to 15, wherein the one or more additives are selected from the group comprising plasticizers, solvents, additional binders, colorants, stabilizers, adhesion control agents, chain transfer agents, UV absorbers, dispersing aids, non-radical crosslinking crosslinkers, viscosity modifiers, and hydrogen bond accepting additives, or combinations thereof. [Item 17] a dimensionally stable carrier layer as layer L1; at least one photosensitive layer as layer L2; Optionally, one or more additional layers Including, Item 1. A developable relief precursor wherein layer L2 comprises the photosensitive composition according to item 1. [Item 18] 18. The relief precursor according to item 17, wherein the relief precursor has an AOX value of less than 3.2 mg / L, preferably less than 3 mg / L, more preferably less than 2.8 mg / L, even more preferably less than 2.6 mg / L, wherein the AOX value is determined according to the method as described in example 2. [Item 19] Item 19. The relief precursor according to item 17 or 18, wherein the relief precursor allows for isolated dot profiles, the dot profiles having a diameter of 100 μm or less. [Item 20] 20. The relief precursor according to any one of items 17 to 19, wherein the relief precursor allows for separated dot profiles with a diameter difference of less than 14%, preferably less than 12%, more preferably less than 10%, even more preferably less than 6%, wherein the diameter difference is determined according to the method as described in example 2. [Item 21] 21. The relief precursor according to any one of items 17 to 20, wherein layer L2 has a thickness in the range of 25 μm to 5000 μm. [Item 22] 22. The relief precursor according to any one of items 17 to 21, wherein the layer L1 comprises a metal sheet, steel, an alloy, a natural or artificial polymer, a polymer blend, a polymer film, or any combination thereof. [Item 23] 23. The relief precursor according to any one of items 17 to 22, wherein the one or more additional layers are selected from the group comprising a barrier layer, a laser ablatable mask layer, an adhesive layer, a UV / VIS light and / or IR light absorbing layer, a monomer diffusion control layer, a surface control layer, a protective cover foil and / or a protective cover film, or a combination thereof. [Item 24] - providing at least one dimensionally stable carrier layer; - optionally applying an adhesive layer and / or adhesive treatment onto said dimensionally stable carrier layer; - providing a photosensitive composition on the at least one dimensionally stable carrier layer; - optionally applying one or more additional layers and / or treatments; Including, The photosensitive composition is the photosensitive composition according to item 1. A method for making a developable relief precursor. [Item 25] 25. The method for making a water-developable relief precursor according to item 24, wherein the one or more treatments are selected from the group comprising a surface treatment, an adhesion treatment, a corona treatment, a flame treatment, a chemical treatment, a plasma treatment, a top coating treatment, or a combination thereof. [Item 26] 2. Use of a photosensitive composition according to item 1 for the production of a relief precursor and / or a relief structure. [Item 27] 18. Use of a developable relief precursor according to item 17 for the production of a relief structure. [Item 28] 28. Use according to item 27, wherein the relief structure is a flexographic printing plate, a letterpress plate, a letterpress printing plate, a pad printing plate, a (flexible) printed circuit board, an electronic element, a microfluidic element, a microreactor, a foretic cell, a photonic crystal, an optical element or a Fresnel lens. [Item 29] - providing a relief precursor comprising the photosensitive composition according to item 1; - exposing the photosensitive composition to electromagnetic radiation, preferably imagewise; - Removal of unexposed areas with the help of developer 1. A method for producing a relief structure, comprising: [Item 30] 30. The method for producing a relief structure according to item 29, wherein the exposing step is performed through an ablated mask layer and / or the exposing step is performed through a mask arranged between the photosensitive layer and a source of electromagnetic radiation. [Item 31] 31. The method for producing a relief structure according to item 29 or 30, wherein the developer is water, one or more aqueous solutions, a polar solvent, or a combination thereof. [Item 32] 32. The method for producing a relief structure according to any one of items 29 to 31, wherein the developer has an AOX of 3.2 mg / L or less, preferably 3 mg / L or less, more preferably less than 2.8 mg / L, most preferably 2.6 mg / L or less, and wherein the AOX value is determined according to the method as described in Example 2. [Item 33] A relief structure obtained according to the method according to item 29, - said relief structure has an AOX of less than 3 mg / L, preferably less than 2.8 mg / L, even more preferably less than 2.6 mg / L, said AOX value being determined according to the method as described in Example 2; the relief structure has a curl value of less than 4, preferably less than or equal to 3.5, the curl value being determined according to the method as described in Example 2, a relief structure, [Example]

[0184] The invention described above is further illustrated by the following examples, which are not intended to be construed in any way as imposing limitations on the scope of the disclosure or claims of the invention appended hereto. Rather, it should be understood that the examples set forth below are presented herein to enable those skilled in the art to better understand the invention.

[0185] [Example 1] This example demonstrates that ethylenically unsaturated monomers as component E containing ionic groups according to the present invention achieve improved AOX or EOX values, or both. The AOX values ​​are shown in Table 1.

[0186] [Table 1]

[0187] (HPPE) and (BHPD) represent acrylates typically used in the industry as comparative examples, including 2-hydroxy-3-phenoxypropylprop-2-enoate and 1,4-butanediylbis[oxy(2-hydroxy-3,1-propanediyl)]diacrylate, respectively; such components do not have ionic groups and represent the component EM.

[0188] TMAEMC, MAPTAC, ADAMQUAT, and Na-AMPS have an ionic group and represent component E of the present invention.

[0189] Indeed, the selected ethylenically unsaturated monomers provide more desirable AOX and / or EOX values, as measured or determined according to the measurement methods described further herein.

[0190] (Measurement of AOX of ethylenically unsaturated monomer (component E)) The AOX values ​​of the ethylenically unsaturated monomers as component E were measured on monomer samples in aqueous solution, each with a solids content as listed in Table 1. The values ​​were determined as follows: AOX was measured in accordance with the "DIN EN ISO 9562" standard (according to 6.2.1.). If the dissolved anion concentration of the sample, determined in accordance with the "DIN EN ISO 10304-1" standard, exceeded 1000 mg / kg, the sample was diluted with grade 1 water as specified in ISO 3696:1987 before analysis to achieve a dissolved anion concentration of 1000 mg / kg, determined in accordance with the "DIN EN ISO 10304-1" standard. In this case, the AOX values ​​were back-calculated to the undiluted sample and listed in Table 1.

[0191] (AOX measurement of ethylenically unsaturated compounds (component EM)) The AOX value of the ethylenically unsaturated monomer containing no ionic group as component EM was measured in the same manner as in the case of component E described above.

[0192] (Measurement of EOX of Ethylenically Unsaturated Monomers (Components E and EM)) The ethylenically unsaturated components EOX were measured as follows: EOX was measured according to the DIN 38414-17 standard using i-hexane as the solvent. A similar trend to the AOX values ​​was observed.

[0193] [Example 2] This example demonstrates that relief precursors and relief structures comprising the photosensitive compositions described herein achieve improved properties. Specifically, with respect to the nuisance curl phenomenon, the compositions of the present invention provide a beneficial effect on curl by reducing unwanted curl at the side edges. Furthermore, it is shown that the formulations of the present invention as described herein achieve improved dot size with less deviation, improved flexibility, extended wear time, and improved AOX values.

[0194] [Table 2]

[0195] To prepare the photopolymerizable printing plate samples, the following procedure was performed: First, a photosensitive composition was prepared using the following components: 24 parts by weight of a functionalized copolymer was added as component B. The preparation of this functionalized copolymer is further described below.

[0196] As component B, 21.84 parts by weight of partially hydrolyzed polyvinyl acetate with a degree of hydrolysis of 88% and a viscosity of 3 mPas.

[0197] 21.84 parts by weight of hydrogen bond-forming additive polyvinyl alcohol / polyethylene glycol graft copolymer as component B. This component was obtained by grafting vinyl acetate onto polyethylene glycol having a molecular weight between 1,000 and 50,000, followed by hydrolysis to a degree of hydrolysis of 97% and a viscosity of 5 mPas, measured at 20°C using a falling-ball viscometer according to DIN 53 015. The grafting of vinyl acetate onto polyethylene was carried out, for example, as described in DE-A-2 846 647.

[0198] The above components were dissolved in a mixture of 87 parts by weight of water and 53 parts by weight of n-propanol at a temperature of 85° C., and the solution was stirred until homogeneous.

[0199] Subsequently, 28 parts by weight of an ethylenically unsaturated compound, 2-hydroxy-3-phenoxypropyl prop-2-enoate (HPPE), was added as component EM.

[0200] The following was then added to the solution: 1.5 parts by weight of the initiator, benzyl dimethyl ketal, were added as component P. Further additives as component A, 0.3 parts by weight of the thermal inhibitor, N-nitrosocyclohexylhydroxylamine, potassium salt, 0.01 parts by weight of Safranin T (CI 50240) as dye, and 0.25 parts by weight of the surface additive BYK 370 (BYK-Chemie GmbH), were added.

[0201] The solution was stirred at a temperature of 85° C. until homogeneous.

[0202] This photosensitive solution was then cast onto a dimensionally stable protective cover film that had been pre-coated with a 3.2 μm-thick laser-ablatable mask layer comprising a polymer binder and carbon black. This cover film pre-coated with a laser-ablatable mask layer was obtained as follows: First, a solution was prepared from 91 kg of toluene, 91 kg of n-propanol, and 23 kg of benzyl alcohol. This solvent mixture was then heated to 70°C. Next, 23.4 kg of a soft elastic polyamide with a glass transition temperature of 5°C, a softening point of 135-145°C, and a melt flow index of 10 g / min was added to the solution. Subsequently, a total of 12.6 kg of carbon black (average particle size 25 nm, BET 180 m) was added. 2 / g) was added in four portions (3.15 kg per hour) with stirring. After the final addition, the dispersion was stirred at 70°C for 24 hours and then cooled to 30°C. The reaction batch was then milled in a stirred ball mill at a throughput of 240 kg / h for 5 hours and filtered through a 10 μm filter. The reaction solution was stirred briefly, and then a 130 μm wet coating was applied to a 125 mm thick PET film at a speed of 6.3 m / min. The dry film thickness of the applied laser-ablatable layer was determined gravimetrically to be 3.2 μm.

[0203] After casting, the cast photosensitive solution, along with the PET film and mask layer, was laminated onto a dimensionally stable carrier layer using a 1:1 ratio of water and n-propanol. The latter used a PET layer coated with a 250 μm thick adhesive layer. The resulting laminated layer had a total thickness of 1100 μm and measured 12 × 12 cm. The plate was dried in a drying cabinet at 60 °C for 3 hours.

[0204] The aforementioned functionalized copolymer was a functionalized polyvinyl acetate prepared according to DE 3322994. For this purpose, 50 parts by weight of partially hydrolyzed polyvinyl acetate (degree of hydrolysis 82 mol%, average molecular weight 30,000 g / mol) was suspended in 150 parts by weight of toluene and then mixed with 8 parts by weight of methacrylic anhydride, 0.4 parts by weight of methylimidazole, and 0.05 parts by weight of Kerobit TBK. The heterogeneous reaction mixture was stirred at 85°C for 5 hours, after which the reaction product was separated, washed with toluene, and dried in a drying cabinet at 50°C for 12 hours, resulting in a copolymer composition having 3.4 mol% vinyl (meth)acrylic acid units, 81.0 mol% vinyl alcohol units, and 15.6 mol% vinyl acetate units.

[0205] A relief precursor as Sample 2a was created as described above. Photosensitive compositions of Samples 2b-g were prepared as described above for Sample 2a, except that the first ethylenically unsaturated compound HPPE as Component EM was partially replaced with a second ethylenically unsaturated compound as Component E containing an ionic group according to the present invention, thereby creating Samples 2b-2g with the amounts of Component E as listed in Table 2.

[0206] For all samples, the following determinations were made:

[0207] (Determining the rinsing time (minutes)) Wash-out times are reported in Table 2 as minimum development times (minutes). This value was determined as follows: Unexposed relief precursor plates had their protective cover film removed and were washed with water, with the aid of a brush, in a Nyloprint® Combi CW35x50 (Flint Group) until the laser-ablatable mask layer and photosensitive layer were completely removed. The minimum time required to achieve complete removal of the photosensitive layer was reported as wash-out time in minutes.

[0208] (Measurement of precursor curl (mm)) Relief precursor plates that had not been subjected to laser ablation, exposure, or washout were stored with the carrier layer facing downward at room temperature (19-22°C) without a protective cover film for two days. During this storage period, four corners of the relief precursor plate curled upward, as shown, for example, in Figures 4A and 4B. The distance was measured at the two corners that showed the most curl, and the arithmetic mean of the two measurements was reported in mm. The distance can be understood as the distance between the surface on which the relief precursor was placed and each curled corner of the relief precursor, as shown, for example, in Figure 4B, which shows surface 40, relief precursor RP, and the measured distance d.

[0209] (Determining the optimal exposure time (4 minutes)) The suitable exposure time was determined according to the following method. The protective cover film layer of the relief precursor plate was removed. The laser-ablatable mask layer was ablated using ThermoFlexx20 (Xeikon) software Multiplate Version 3.1.0.48 and the following parameters: wavelength 1064 nm, 10 revolutions per second, and laser power 22 W. During laser ablation, a typically used test motif was image-transferred onto the mask layer using a resolution of 2540 dpi. The test motif included halftone wedge-shaped areas of graduated tonal values ​​(0.4% to 2.0% halftone areas in 0.4% increments) with a resolution of 146 lines per inch (lpi). The ablated precursor was then exposed for different times using a Nyloprint® Combi CW35x50 (Flint Group) with a TL09 tube. The prints were then printed on a Nyloprint® Combi CW35x50 (Flint Group) with a brush, followed by rinsing with water and subsequent drying at 65°C for 15 minutes, after which the exposure time at which a 2% halftone screen (146 lines per inch (lpi)) could be reproduced without error was determined. In these examples, an exposure time of 4 minutes was found and used for the examples listed in Table 2.

[0210] (Measurement of curl (mm) of relief structure) The curl of the relief structure was determined for relief structure plates measuring 12 x 12 cm. To do this, the protective cover film layer was removed from the relief precursor plates. The laser-ablatable mask layer was completely ablated using ThermoFlexx20 (Xeikon) software Multiplate Version 3.1.0.48 and the following parameters: wavelength 1064 nm, 10 revolutions per second, and laser power 22 W. The plates from which the laser-ablatable mask layer had been completely removed were exposed for 4 minutes using a Nyloprint® Combi CW35x50 (Flint Group) equipped with a TL09 tube. After exposure, each plate was subjected to rinsing using a brush for the corresponding rinsing time, listed as the minimum development time (minutes) in Table 2. The rinsing was performed with water. The relief structures were then dried in the dryer of the Nyloprint® Combi CW35x50 (Flint Group) at 65°C for 15 minutes. The plates were then stored with the carrier layer facing downward and the exposed photosensitive layer facing upward. This storage occurred at room temperature (19-22°C) for two days. During this time, all four corners of the plate curled upward. The distance between the two corners that showed the most curl was measured, and the arithmetic mean of these two measurements was reported in mm. The distance can be understood as the distance between the surface on which the relief structure rests and each curled corner of the relief structure.

[0211] (Measurement of dot diameter (μm) and diameter difference (%)) The dot diameter that could be created on the relief structure was targeted at 22 μm. This target and / or diameter was determined as follows: The relief precursor plate had the protective cover film layer removed. The laser-ablatable mask layer was ablated using ThermoFlexx20 (Xeikon) software Multiplate Version 3.1.0.48 and the following parameters: wavelength 1064 nm, 10 revolutions per second, and laser power 22 W. During laser ablation, a typically used test motif was image-transferred onto the mask layer using a resolution of 2540 dpi. The test motif included a halftone wedge area of ​​graduated tonal values ​​(0.4% to 2.0% halftone range in 0.4% increments) with a resolution of 146 lines per inch (lpi). After laser ablation, the test motif was exposed, washed out, and dried as previously described. The tonal values ​​and diameters of dots formed on areas of the relief structure corresponding to the halftone regions of the test motif (0.4% to 2.0% halftone regions in 0.4% increments) were then measured using a Vipflex 334 and "PlateQuality Flexo" software (version 1.2.1.11). The following parameters were used: plate type "Flexoplatten," color contrast set to "Auto," and the fuzzy limiting algorithm set to setting 4. The average diameter of 50 automatically evaluated dots was reported for a tonal value of 1.2% and listed in Table 2 as "Dot Diameter (μm)." The ideal theoretical value was 22 μm, but the closer the reported value was to this ideal value, the more accurate and predictable it is. Therefore, a smaller deviation is preferable. This deviation value represents the deviation between the achieved and measured diameter of dots formed on the photosensitive layer, and this value is reported in Table 2 for each sample as "Diameter Difference (%)."

[0212] (Tensile stress at 50% strain (N / mm 2 ) Measurement The flexibility of the relief structure was determined by stress-strain measurements using the tensile stress at 50% strain (σ50, in N / mm 2The relief precursor plates were investigated by measuring the surface roughness (SSR) of the laser-ablatable mask layer. The protective cover film layer and carrier layer were removed by peeling them off. It should be noted that the samples were free of any damage (e.g., cracks) and / or foreign matter (e.g., bubbles, particles, etc.). Using a Nyloprint® Combi CW35x50 (Flint Group) with a TL09 tube, the precursor samples were exposed (from above) for 4 minutes, with the laser-ablatable mask layer facing downwards. After this exposure, the sample plates were subjected to rinsing, aided by the use of a brush to remove the laser-ablatable mask layer, for the corresponding rinsing times listed as "Minimum Development Time (min)" in Table 2. The rinsing was performed with water. The relief structures were then dried at 65°C for 15 minutes in the dryer of the Nyloprint® Combi CW35x50 (Flint Group). After drying, the plates were stored overnight at room temperature, and for each sample, four specimens were punched out of the relief structure plate, the specimens conforming to the ISO 527-2 standard and having a shape also defined as Zwick specimen form 5A by Zwick Roell AG. Measurements were carried out at room temperature (around 20°C) using a Zwick Roell 72.5 instrument manufactured by Zwick Roell AG and testexpert software version V10.0, according to a method based on DIN 53504, with a pretension force of 0.01 MPa and a strain rate of 100 mm / min. For each sample, the tensile stress at 50% strain of the four punched specimens was measured. The arithmetic mean of the tensile stress measured for each sample was calculated in units of N / mm. 2 The values ​​are reported in Table 2 as the tensile stress at 50% strain (σ50).

[0213] (Measurement of AOX in mg / L of printing plate precursor) The influence of the environment was investigated by measuring the AOX values. These values ​​were determined as follows: A 5 x 5 cm unirradiated relief precursor plate without a cover film but with a laser-ablatable mask layer was weighed and then completely immersed in 500 mL of water, representative of a developer. Ultrasonic treatment was used to achieve rapid dissolution of the photosensitive layer. After dissolution of the photosensitive layer, the undissolved residue of the relief precursor was dried and measured. The weight difference before and after was between 3.6 g and 4.9 g. Normalization was performed to 2.5 g / L for each sample. The AOX was measured in accordance with the "DIN EN ISO 9562" standard (according to 6.2.1). If the dissolved anion concentration of the sample determined according to the "DIN EN ISO10304-1" standard was greater than 1000 mg / kg, the sample was diluted before analysis with grade 1 water as specified in ISO3696:1987 to achieve a dissolved anion concentration of 1000 mg / kg determined according to the "DIN EN ISO10304-1" standard. In this case, the AOX value was back-calculated to the undiluted sample.

[0214] (Measurement of duration of use at the time of crack initiation) The service life at the onset of cracking was measured as follows. Printing tests were conducted using UV letterpress printing ink UVONOVA (Flint Group). For this test, the printing plate was stretched on a printing cylinder and printed on a conventional letterpress printing unit (press: Nilpeter-F2400). The printing substrate was single-sided coated "FSC" paper manufactured by Avery Dennison. The printing speed was 50 m / min. The halftone screen size was 146 lpi. The tonal value gain (1% to 10% halftone region) of characteristic printed lines was measured relative to the ideal tonal value source image (1:1 curve). The results of the printing tests are summarized in Table 2. After printing, the printing plate was inspected for cracks in the solid areas. The service life was determined over multiple test runs. During the multiple test runs, parameters such as printing speed, printing pressure, and substrate hardness were varied. Each sample was given one of the following values: (-), (0), or (+), which represents the average service life achieved by each sample during multiple test trials. Here, (-) represents a shorter service life, which means more maintenance and / or replacement of the relief structure. A value of (0) means that a longer service life can be achieved, although not significantly. A value of (+) indicates a significant improvement in service life. [Explanation of symbols]

[0215] 1. Energy Source 2. Electromagnetic Radiation 11 Laser Beam 22 Exposure Area 23 Relief 30 Printing Patterns 31 Printing Pattern 32 Opening Area 35 Relief 36 Relief 40 surface RP Relief Precursor L1 dimensionally stable carrier layer L2 photosensitive layer CL Cover Layer OL Any layer ML Laser ablatable mask layer OP original pattern PP printing pattern PS printing base material RS1 Relief Structure RS2 relief structure d distance

Claims

1. 1. A developable relief precursor photosensitive composition comprising: at least one ethylenically unsaturated monomer as component E; at least one photoinitiator or photoinitiator system as component P; at least one water-soluble and / or water-dispersible binder as component B; optionally one or more additives as component A; Component E comprises at least one ionic group; Component E is present in an amount of 0.1 to 30 wt %, based on the total weight of the photosensitive composition; Component E has a solubility in water of 200 g / l or more at 20°C and 1 atmosphere in water having a pH of 7, and / or A photosensitive composition, wherein component E has a vapor pressure that is less than 50 hPa at 25°C, and the vapor pressure is determined in accordance with the "ASTM E1194-17" standard for vapor pressures less than 1 Pa and in accordance with the "ASTM D2879-18" standard for vapor pressures of 1 Pa or greater.

2. 10. The photosensitive composition of claim 1, wherein component E is present in an amount of 0.5 to 20 wt %, based on the total weight of the photosensitive composition.

3. 3. The photosensitive composition according to claim 1, wherein component E has a solubility in water of pH 7 at 20° C. and 1 atmosphere in the range of 500 to 1500 g / l.

4. The photosensitive composition according to any one of claims 1 to 3, wherein component E has a molecular weight in the range of 100 to 1000 g / mol.

5. The photosensitive composition of any one of claims 1 to 4, wherein component E comprises at least one of an acrylate group, a methacrylate group, an acrylamide group, a vinyl group, a vinyl ether group, or a combination thereof.

6. A photosensitive composition described in any one of claims 1 to 5, wherein the vapor pressure of component E is less than 45 hPa at 25°C.

7. The photosensitive composition of any one of claims 1 to 6, wherein component E has an AOX value of less than 2600 mg / L.

8. 8. The photosensitive composition of claim 1, wherein the at least one ionic group contained in component E is selected from the group consisting of a quaternary ammonium group, a carboxylate group, a sulfonate group, a sulfonium group, a phosphonium group, and combinations thereof.

9. The photosensitive composition of any one of claims 1 to 8, wherein component E is a quaternized amino-functional monomer.

10. 10. The photosensitive composition according to claim 1, further comprising an ethylenically unsaturated compound as component EM, wherein said component EM does not have an ionic group.

11. 11. The photosensitive composition of claim 10, wherein component EM is present in an amount of 0.5 to 50 wt %, based on the total weight of the photosensitive composition, and the ratio of EM / E is between 0.1 and 10.

12. 12. The photosensitive composition of claim 1, wherein component P is selected from the group comprising benzil ketals, hydroxyketones, aminoketones, acylphosphine oxides, bisacylphosphine oxides, thioxanthones, anthraquinones, coumarins, hexaarylbisimidazoles, benzophenones, and combinations thereof.

13. 10. The photosensitive composition of claim 1, wherein component P is a photoinitiator system further comprising a coinitiator, the coinitiator being selected from the group consisting of amines, thiols, thioethers, aminoalcohols, thioetheramines, and combinations thereof.

14. Component B is Polyvinyl alcohol, polyvinyl acetate, partially hydrolyzed polyvinyl acetate, functionalized polyvinyl alcohol, Functionalized polyvinyl acetate, functionalized partially hydrolyzed polyvinyl acetate, Polyvinyl acetal, Copolymers of polyvinyl acetate and at least one other monomer, a polyvinyl acetate polymer or copolymer having at least one grafted unit; Polyurethane, polyacrylate, polyamide, polyether 10. The photosensitive composition of claim 1, wherein the photosensitive composition is selected from the group consisting of:

15. the functionalized polyvinyl alcohol and / or the functionalized partially hydrolyzed or non-hydrolyzed polyvinyl acetate is functionalized with an ethylenically unsaturated group; and / or the at least one other monomer in the copolymer of polyvinyl acetate is ethylene; and / or the at least one grafted unit of the polyvinyl acetate polymer or copolymer is polyethylene glycol; The photosensitive composition of claim 14.

16. 16. The photosensitive composition of any one of claims 1 to 15, wherein the one or more additives are selected from the group comprising plasticizers, solvents, additional binders, colorants, stabilizers, adhesion control agents, chain transfer agents, UV absorbers, dispersing aids, non-radical crosslinking crosslinkers, viscosity modifiers, and hydrogen bond accepting additives, or combinations thereof.

17. a dimensionally stable carrier layer as layer L1; at least one photosensitive layer as layer L2; Optionally, one or more additional layers Including, A developable relief precursor wherein layer L2 comprises the photosensitive composition of claim 1.

18. 18. The relief precursor of claim 17, wherein the relief precursor allows for discrete dot profiles, the dot profiles being 100 [mu]m or less in diameter.

19. 19. A relief precursor according to claim 17 or 18, wherein said relief precursor allows for isolated dot profiles with a diameter difference of less than 14%.

20. Relief precursor according to any one of claims 17 to 19, wherein layer L2 has a thickness in the range of 25 μm to 5000 μm.

21. The relief precursor according to any one of claims 17 to 20, wherein the layer L1 comprises a metal sheet, steel, an alloy, a natural or artificial polymer, a polymer blend, a polymer film, or any combination thereof.

22. 22. The relief precursor according to any one of claims 17 to 21, wherein the one or more additional layers are selected from the group comprising a barrier layer, a laser ablatable mask layer, an adhesive layer, a UV / VIS light and / or IR light absorbing layer, a monomer diffusion control layer, a surface control layer, a protective cover foil and / or a protective cover film, or a combination thereof.

23. - Providing at least one dimensionally stable carrier layer; - optionally applying an adhesive layer and / or adhesive treatment onto said dimensionally stable carrier layer; - providing a photosensitive composition on said at least one dimensionally stable carrier layer; - optionally applying one or more additional layers and / or treatments; Including, The photosensitive composition is at least one ethylenically unsaturated monomer as component E; at least one photoinitiator or photoinitiator system as component P; at least one water-soluble and / or water-dispersible binder as component B; optionally one or more additives as component A; Component E comprises at least one ionic group; Component E is present in an amount of 0.1 to 30 wt %, based on the total weight of the photosensitive composition; A method for making a developable relief precursor.

24. - providing at least one dimensionally stable carrier layer; - optionally applying an adhesive layer and / or adhesive treatment onto said dimensionally stable carrier layer; - providing a photosensitive composition on said at least one dimensionally stable carrier layer; - optionally applying one or more additional layers and / or treatments; Including, The photosensitive composition is the photosensitive composition of claim 1. A method for making a developable relief precursor.

25. 25. The method of making a developable relief precursor of claim 23 or 24, wherein the one or more treatments are selected from the group comprising a surface treatment, an adhesion treatment, a corona treatment, a flame treatment, a chemical treatment, a plasma treatment, a top coating treatment, or a combination thereof.

26. 10. Use of the photosensitive composition according to claim 1 for the production of a relief precursor and / or a relief structure.

27. 20. Use of a developable relief precursor according to claim 17 for the production of a relief structure.

28. 28. Use according to claim 27, wherein the relief structure is a flexographic printing plate, a letterpress plate, a letterpress printing plate, a pad printing plate, a (flexible) printed circuit board, an electronic element, a microfluidic element, a microreactor, a forehetic cell, a photonic crystal, an optical element or a Fresnel lens.

29. The method of claim 29, comprising providing a relief precursor comprising a photosensitive composition, The photosensitive composition comprises: at least one ethylenically unsaturated monomer as component E; at least one photoinitiator or photoinitiator system as component P; at least one water-soluble and / or water-dispersible binder as component B; optionally one or more additives as component A; Component E comprises at least one ionic group; Component E is present in an amount of 0.1 to 30 wt %, based on the total weight of the photosensitive composition; - exposing said photosensitive composition to electromagnetic radiation, preferably imagewise; - Removal of the unexposed areas with the help of a developer; Including, A method for producing a relief structure, wherein the exposing step is performed through an ablated mask layer and / or the exposing step is performed through a mask positioned between the photosensitive layer and a source of electromagnetic radiation.

30. - providing a relief precursor comprising a photosensitive composition according to claim 1; - exposing said photosensitive composition to electromagnetic radiation, preferably imagewise; - Removal of the unexposed areas with the help of a developer; 1. A method for producing a relief structure, comprising:

31. 31. The method for producing a relief structure according to claim 30, wherein the exposing step is performed through an ablated mask layer and / or the exposing step is performed through a mask arranged between the photosensitive layer and a source of electromagnetic radiation.

32. The method for producing a relief structure according to any one of claims 29 to 31, wherein the developer is water, one or more aqueous solutions, a polar solvent, or a combination thereof.

33. A method for producing a relief structure according to any one of claims 29 to 32, wherein the developer has an AOX value of 3.2 mg / L or less.

34. A relief structure obtainable according to the method of claim 29 or 30, - the relief structure has an AOX value of less than 3 mg / L; said relief structure has a curl value of less than 4, a relief structure, wherein one or more of the following applies:

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