Specific benzopyrylium salts as dyestuffs for photopolymer compositions

Abstract

The invention relates to a benzopyrylium dyestuff of formula (I), wherein R200,R201, R202, R203, R204, R205, R206, R207 and R208 each independently represent hydrogen, C1- to C16-alkyl, C4- to C7-cycloalkyl C7- to C16-aralkyl, C6- to C10-(het)aryl, hydroxy, C1- to C6- alkoxy, or dialkylamino , wherein the dialkylamino is selected from the group consisting of diethylamino, dimethylamino, diisopropylamino, a six-membered, saturated ring linked via the N of the amino group, which can also include an N or O and can be substituted by non-ionic random groups or a combination of at least two thereof, and / or R200 with R201 or R201 with R202 or R202 with R203 and / or R205 with R206 and / or R206 with R207 each independently together form a -CH=CH-CH=CH-bridge, with A representing a -CH2or a -CH2-CH2-bridge, wherein the anion Ann- has a molecular weight of ≥ 200 g / mol and contains no halogen atom.

Description

[0001] Special benzopyrylium salts as dyes for photopolymer compositions

[0002] The invention relates to benzopyrylium dyes in the form of benzopyrylium salts, which can be used in particular as dyes in photopolymer compositions for holographic media. Furthermore, the synthesis of the specific benzopyrylium salts is disclosed, as well as photopolymer compositions comprising at least matrix polymers, writing monomers, and a photoinitiation system (PIS), wherein the PIS contains at least one benzopyrylium salt according to the invention as a dye; holographic media comprising matrix polymers, writing monomers, and a PIS, wherein the PIS contains at least one benzopyrylium salt according to the invention as a dye; and layer structures and displays comprising a holographic medium according to the invention, each of which is the subject of the invention.

[0003] A wide variety of photopolymer compositions are known in the prior art. For example, WO 2008 / 125229 describes a photopolymer composition and a photopolymer obtainable therefrom, which comprise polyurethane matrix polymers, one or more acrylate-based writing monomers, and a PIS containing a coinitiator and at least one dye. When using photopolymers, the refractive index modulation Δn generated by holographic exposure plays a crucial role. During holographic exposure, the interference field consisting of the signal and reference light beams (in the simplest case, that of two plane waves) is imaged into a refractive index grating by the local photopolymerization of writing monomers such as high-index acrylates at locations of high intensity in the interference field. The refractive index grating in the photopolymer (the hologram) contains all the information of the signal light beam.By illuminating the hologram with only the reference light beam, the signal can then be reconstructed. The strength of the reconstructed signal in relation to the strength of the incident reference light is called diffraction efficiency, or DE.

[0004] In the simplest case of a hologram resulting from the superposition of two plane waves, the DE results from the quotient of the intensity of the light diffracted during reconstruction and the sum of the intensities of non-diffracted and diffracted light. The higher the DE, the more efficient a hologram is in terms of the amount of reference light required to make the signal visible with a given brightness. For many holographic applications of photopolymer compositions or the holographic media formed from them, however, not only the holographic performance plays an important role; it is equally crucial that the media exhibit excellent bleachability, i.e., high transmission across the entire visible spectral range from 400 nm to 800 nm. This depends largely on the dye used in the photoinitiator system of the photopolymer composition.

[0005] Suitable dyes for photopolymers have already been widely described. For example, EP 2638544 describes various classes of cationic dyes that can be used as suitable sensitizers in combination with coinitiators such as triarylalkyl borate salts in photopolymer compositions. The main requirements for such dyes, in addition to the aforementioned good bleachability, are rapid initiation of radical polymerization through electron or energy transfer with a suitable coinitiator, as well as good compatibility with the other components of the photopolymer composition to avoid the formation of inhomogeneities or turbidity in the photopolymer.According to EP 2638544, the following classes of dyes are well suited for photopolymers: acridine dyes, xanthene dyes, thioxanthene dyes, phenazine dyes, phenoxazine dyes, phenothiazine dyes, tri(het)arylmethane dyes - especially diamino and triamino(het)arylmethane dyes, mono-, di- and trimethine cyanine dyes, hemicyanine dyes, externally cationic merocyanine dyes, externally cationic neutrocyanine dyes, nullmethine dyes - especially naphtholactam dyes, streptocyanine dyes. Such dyes are also described, for example, in H. Bemeth in Ullmann's Encyclopedia of Industrial Chemistry, Azine Dyes, Wiley-VCH Verlag, 2008, H. Bemeth in Ullmann's Encyclopedia of Industrial Chemistry, Methine Dyes and Pigments, Wiley-VCH Verlag, 2008, T. Gessner, U. Mayer in Ullmann's Encyclopedia of Industrial Chemistry, Triarylmethane and Diarylmethane Dyes, Wiley-VCH Verlag, 2000.

[0006] However, it was found that although very good holographic performance can be achieved with these known dyes, the bleachability criterion is not yet satisfactorily met.

[0007] An object of the invention was therefore to provide a dye that at least partially overcomes at least one of the disadvantages described above. Furthermore, an object of the present invention was to provide a photopolymer composition of the type mentioned above which, after bleaching with the aid of a suitable radiation source, provides particularly high transmission across the entire visible spectral range.

[0008] Surprisingly, it was found that by using certain benzopyrylium salts as dyes in photopolymer compositions of the type mentioned above, a higher transmission can be achieved over the entire visible spectral range from 400 nm to 800 nm than with the previously known dyes, such as those from EP 2638544.

[0009] A first aspect of the invention relates to a benzopyrylium dye of the formula (I) wherein

[0010] R 200 , R 201 , R 202 , R 203 , R 204 , R 205 , R 206 , R 207 and R 208 independently of one another each represent hydrogen, alkyl, preferably C1 to C 16 -alkyl, particularly preferably C1- to C 10-Alkyl, more preferably C1- to C6-alkyl, most preferably C1- to C4-alkyl, most preferably methyl; cycloalkyl, preferably C4- to C7-cycloalkyl, particularly preferably C5- to C6-cycloalkyl, aralkyl, preferably C7- to C 16 - Aralkyl, particularly preferably C8 to C 12 -Aralkyl, aryl, preferably phenyl, (het)aryl, preferably C6- to C 10 -(Het)Aryl, hydroxy, alkoxy, preferably C1- to C6-alkoxy, particularly preferably methoxy, or dialkylamino,

[0011] A represents a -CH2- or a -CH2-CH2 bridge, and the anion An n- ' has a molecular weight of ≥ 200 g / mol and does not contain a halogen atom, with n from 1 to 3. More preferably, the anion An n-' a molecular weight of ≥ 250 g / mol, more preferably ≥ 300 g / mol, particularly preferably ≥ 350 g / mol. It is preferred that the anion An- has a molecular weight in a range from ≥ 200 g / mol to 1000 g / mol, more preferably from ≥ 250 g / mol to 900 g / mol, particularly preferably from ≥ 300 g / mol to 800 g / mol, very particularly preferably from ≥ 350 g / mol to 700 g / mol.

[0012] Preferably, R 200 with R 201 or R 201 with R 202 or R 202 with R 203 or R 205 with R 206 or R 206 with R 207 each independently of each other together form a -CH=CH-CH=CH-bridge.

[0013] Preferably, the (het)aryl is an aryl radical which is substituted at least one position by a heteroatom such as O, N, P, S or a combination thereof.

[0014] It is preferred that the dialkylamino preferably represents a five- or six-membered saturated ring attached via the N of the amino group, which may additionally contain an N or O and / or be substituted by nonionic radicals. The nonionic radicals are preferably selected from the group consisting of alkyl, alkoxy, hydroxy, thiol, aryl, (het)aryl, amine, amide, or a combination of at least two thereof.

[0015] It was found by chance that in photopolymers, particularly good bleachability, in addition to high DE and Δn values, rapid initiation of radical polymerization and high compatibility with remaining components of the photopolymer composition, is achieved when at least one dye of the formula (I) is included in the photopolymer composition.

[0016] In a preferred embodiment of the benzopyrylium dye of formula (I), R 200 , R 205 , R207 and R 208 each represents hydrogen, A represents a -CH2-CH2 bridge. R 201 , R 202 , R 203 and R 206 independently represent a radical selected from the group consisting of hydrogen, C1- to C 16 -Alkyl, C4- to C7-cycloalkyl, C7- to C 16 -Aralkyl, C6- to C 10 -(Het)Aryl, Hydroxy, C1 to C6 alkoxy or dialkylamino, R 204 represents a radical selected from the group consisting of hydrogen, C1- to C4-alkyl, or an arbitrarily substituted (het)aryl radical or R 201 with R 202 or R 202 with R 203together form a -CH=CH-CH=CH-bridge. The dialkylamino is preferably selected from the group consisting of diethylamino, dimethylamino, diisopropylamino, a six-membered saturated ring attached via the N of the amino group, which may additionally contain an N or O and may be substituted by any non-ionic radicals, or a combination of at least two thereof.

[0017] In a particularly preferred embodiment of the benzopyrylium dye of the formula (I), R 200 , R 205 , R 207 and R 208 for hydrogen, A for a -CH2-CH2 bridge and R 20' is selected from the group consisting of hydrogen, C1- to C4-alkyl, hydroxy, C1- to C4-alkoxy and dialkylamino, where the dialkylamino is selected from the group consisting of diethylamino, dimethylamino, diisopropylamino, a six-membered saturated ring attached via the N of the amino group, which may additionally contain an N or O and may be substituted by any non-ionic radicals or a combination of at least two thereof, R 202 represents hydrogen, C1- to C4-alkyl, hydroxy, C1- to C4-alkoxy, R 203 either stands for hydrogen or with R 202 together form a - CH=CH-CH=CH bridge, R 204 represents hydrogen, C1- to C4-alkyl, or an arbitrarily substituted (het)aryl radical and R 206 represents hydrogen, hydroxy, C1- to C4-alkoxy.

[0018] Furthermore, in a preferred embodiment of the benzopyrylium dye of the formula (I) R 201represents a radical selected from the group consisting of hydrogen, methyl, ethyl, methoxy, ethoxy, dimethylamino and diethylamino.

[0019] The following benzopyrylium dyes (III) to (VIII) are particularly preferred:

[0020] The preferred anion is An n- , here with n = 1, of the benzopyrylium cations described above, an anion with a molecular weight of ≥ 200 g / mol selected from the group of arbitrarily substituted phosphates, arbitrarily substituted phosphonates, arbitrarily substituted sulfonimides, arbitrarily substituted organic borates, such as tetraarylborate, triarylalkylborate or cyanotriarylborate, arbitrarily substituted alkyl or alkenyl sulfates, arbitrarily substituted mono- or di-sulfonates, such as sulfosuccinic acid esters, or the group of arbitrarily substituted organic mono- or di-carboxylates.

[0021] In a preferred embodiment of the benzopyrylium dye, the anion Ann- selected from the group consisting of C8 to C 25 -alkanesulfonates, preferably C 13 - to C 25 -alkanesulfonates, C9 to C 25 -alkanoates, C9- to C 25 -alkenoates, C8- to C 25 -alkyl sulfates, preferably C 13 - to C 25 - Alkyl sulfates, C8 to C 25 -alkenyl sulfates, preferably C 13 - to C 25 -Alkenyl sulfates, polyether sulfates based on at least 5 equivalents of ethylene oxide or 5 equivalents of propylene oxide, bis- C4 to C 25 -alkyl-, C5- to C7-cycloalkyl-, C3- to C8-alkenyl- or C7- to C 11 -Aralkylsulfosuccinates, C8- to C 25 -alkylsulfoacetates, by at least one radical of the group C4- to C 25 -alkyl and / or C1- to C 12 -Alkoxycarbonyl substituted benzenesulfonates, optionally substituted by nitro, cyano, hydroxy, C1- to C 25 -Alkyl, C1- to C 12 -Alkoxy, Amino, C1- to C 12-Alkoxycarbonyl substituted naphthalene or biphenylsulfonates, optionally substituted by nitro, cyano, hydroxy, C1- to C 25 -Alkyl, C1- to C 12 -Alkoxy, C1- to C 12 -Alkoxycarbonyl substituted benzene, naphthalene or biphenyl disulfonates, by dinitro, C6,- to C 25 -Alkyl, C4- to C 12 -Alkoxycarbonyl, benzoyl or toluoyl substituted benzoates.

[0022] Furthermore, the anion is preferably selected from the group of the anions of naphthalenedicarboxylic acid, diphenyl ether disulfonates, sulfonated or sulfated, optionally at least monounsaturated C8 to C 25 -Fatty acid esters of aliphatic C1 to C8 alcohols or glycerol, the bis-(sulfo-C2 to C6 alkyl)-C3 to C 12 -alkanedicarboxylic acid esters, the bis-(sulfo-C2- to C6-alkyl)itaconic acid esters, the (sulfo-C2- to C6-alkyl)- C6- to C 18- alkanecarboxylic acid esters, (sulfo-C2- to C6-alkyl)acrylic or methacrylic acid esters, triscatechol phosphates, tetraphenylborates, cyanotriphenylborates, tetraphenoxyborates, C4- to C 12 -Alkyltriphenylborates, whose phenyl or phenoxy radicals may be substituted by C1- to C4-alkyl and / or C1- to C4-alkoxy, the C4- to C 12 -Alkyl-trinaphthylborates, the tetra-C1- to C 20 - alkoxyborates, the mono- or doubly negatively charged 7,8- or 7,9-dicarbanidoundecaborates, which may be substituted at the B and / or C atoms by one or two C1 to C 12 -alkyl or phenyl groups, the doubly negatively charged dodecahydrodicarbadodecaborates or the B-C1 to C 12 -Alkyl-C-phenyldodecahydrodicarbadodecaborates or a mixture of at least two thereof.

[0023] In a preferred embodiment of the benzopyrylium dye, the anion An n-selected from the group consisting of C8 to C 25 -alkanesulfonates, preferably C 13 - to C 25 -alkanesulfonates, C8 to C 25 -alkyl sulfates, preferably C 13 - to C 25 -alkyl sulfates, bis-C4 to C 25 -alkyl-, C5- to C7-cycloalkyl-, C3- to C8-alkenyl- or C7- to C 11 -Aralkylsulfosuccinates, C8- to C 25 -Alkylsulfo- acetates, by at least one radical of the group C4- to C 25 -alkyl and / or C1- to C 12 -Alkoxy-carbonyl substituted benzenesulfonates and tetraphenylborates or a combination of at least two thereof. Preferably, the anion An n- selected from the group consisting of bis-C4 to C 25 -Alkyl sulfosuccinates, C4- to C 25 -Alkyl substituted benzenesulfonates and tetraphenylborates.

[0024] The anion An is particularly preferred n-' selected from the group consisting of (2-ethylhexyl) sulfosuccinate, dodecylbenzenesulfonate and tetraphenylborate.

[0025] In a particularly preferred embodiment of the benzopyrylium dye, R200, R205, R207 and R208 are hydrogen, A is a -CH2-CH2-bridge, and where

[0026] R201 is selected from the group consisting of hydrogen, C1- to C4-alkyl, hydroxy, C1- to C4-alkoxy, or dialkylamino, wherein the dialkylamino is selected from the group consisting of diethylamino, dimethylamino and diisopropylamino or a combination of at least two thereof, particularly preferably hydrogen,

[0027] R202 represents hydrogen, C1 to C4 alkyl, hydroxy or C1 to C4 alkoxy, particularly preferably hydrogen,

[0028] R203 either represents hydrogen or forms a -CH=CH-CH=CH-bridge with R202, particularly preferably represents hydrogen,

[0029] R204 represents hydrogen, phenyl, particularly preferably hydrogen,

[0030] R206 represents hydrogen, hydroxy or C1 to C4 alkoxy, particularly preferably hydrogen, and the anion An n- is selected from the group consisting of C8 to C 25 -alkanesulfonates, preferably C 13 - to C 25 -alkanesulfonates, C8 to C 25 -alkyl sulfates, preferably C 13 - to C 25 -alkyl sulfates, bis-C4- to C 25 -alkyl-, C5- to C7-cycloalkyl-, C3- to C8-alkenyl- or C7- to C 11 -Aralkylsulfosuccinates, C8- to C 25 -Alkylsulfoacetates bis-C4- to C 25 -Alkyl sulfosuccinates, especially (2-ethylhexyl) sulfosuccinate C4- to C 25-Alkyl substituted benzenesulfonates, in particular dodecylbenzenesulfonate and tetraphenylborates, in particular tetraphenylborate, particularly preferably selected from (2-ethylhexyl)-sulfosuccinate dodecylbenzenesulfonate and tetraphenylborates.

[0031] Another object of the invention relates to a process for the preparation of a benzopyrylium dye, in particular a benzopyrylium dye according to the invention, comprising a multi-stage reaction sequence in which at least the reaction stages are carried out as follows:

[0032] A. In a first reaction step P1.: P1.i. Dissolving an appropriately selected 2-hydroxyarylcarbonyl derivative together with a corresponding indanone or tetralone derivative in a weak acid, preferably glacial acetic acid; P1.ii. Heating the mixture from P1.i. with the addition of a strong acid, preferably at reflux, until complete conversion; P1.iii. Cooling and washing the mixture from P1.ii. with a non-polar, aprotic solvent; P1.iv. Separating the phase insoluble in the non-polar, aprotic solvent and dissolving this phase in water;

[0033] B. in a second reaction stage P2.:

[0034] P2.i. Addition of an alkali salt of the dye anion An n- and a non-polar, aprotic solvent to the aqueous solution from P1.iv.,

[0035] P2.ii. Stirring and, if necessary, heating the mixture from P2.i. and separating the aqueous phase and discarding it, including the salts contained therein,

[0036] P2.iii. Washing the mixture from P2.ii. with water, preferably to the end point and,

[0037] P2.iv. Removal of the solvent, optionally in vacuo, and drying of the benzopyrylium dye according to the invention, optionally in vacuo.

[0038] If the dye precipitates after the first reaction step (PL), it is filtered off, washed with a non-polar, aprotic solvent, and used as a purified product together with water in the second reaction step (P2). If the crude product is insoluble in water, the oily phase containing the crude product is washed with a non-polar, aprotic solvent in step P1.iv. and further processed together with water in the second reaction step (P2).

[0039] The benzopyrylium dye is preferably prepared in a one-pot reaction according to the following reaction equation:

[0040] In the one-pot reaction procedure, in a first reaction stage PL, the corresponding 2-hydroxyarylcarbonyl derivative is dissolved in a 1:1 equivalent ratio together with the corresponding indanone or tetralone derivative in glacial acetic acid in step P1 i. In step P1.ii., a strong acid, preferably with a pKa value of ≤ 4, more preferably ≤ 3, most preferably ≤ 2, most preferably ≤ 1, e.g., sulfuric acid, is slowly added, preferably over a period of 1 to 5 hours, and the mixture is heated at reflux until complete conversion. After cooling to preferably 10 to 40°C, more preferably 20 to 30°C, and especially preferably 23 to 25°C in step P1.iii., the reaction solution is diluted with a nonpolar, aprotic solvent, such as methyl tert-butyl ether (MTBE), and mixed thoroughly. The solvent-insoluble phase is separated in step P1.iv. and dissolved in water.In a second reaction stage P2, in step P2.i., an alkali metal salt of the dye anion and an ester solvent, such as butyl acetate, are added to this aqueous solution to form an ester solvent / water mixture, which is stirred in step P2.ii. with gentle heating, preferably to a maximum of 50°C, more preferably to a maximum of 40°C. The phases are separated in step P2.iii., and the organic phase is washed with water. After removal of the solvent, preferably by heating to 40 to 70°C and drying under vacuum, preferably at 10 to 50 mbar, in step P2.iv., the product is obtained as a highly viscous oil.

[0041] If, according to the above procedure, the crude product precipitates as a solid after the first stage PL, it is filtered off, washed with a non-polar, aprotic solvent, such as MTBE, and used as a purified product together with water in the second stage.

[0042] If the crude product is insoluble in water after the above procedure, the oily phase containing the crude product is washed with a nonpolar, aprotic solvent such as MTBE. The thus purified product is further processed together with water in the second step P2.

[0043] The invention further relates to the use of the benzopyrylium dye according to the invention, preferably as part of a two-component photoinitiator system, in photocurable formulations in combination with a suitable electron donor to improve the bleachability of photocurable materials. The benzopyrylium dyes according to the invention are preferably used after irradiation with actinic radiation to initiate free-radical polymerizations. Electron donors selected from triarylalkyl borates, trifluoroalkyl borates, tertiary amines, pentacoordinated silicates, and dihydropyridines are preferably used.The benzopyrylium dye according to the invention is preferably used together with the electron donor in a three-component photoinitiator system together with an electron acceptor selected from iodonium salts, sulfonium salts, trichlorotriazines, electron-deficient trihalomethylaromatics, and Katritzky salts, or a mixture of at least two thereof. The electron-deficient trihalomethylaromatics are preferably trichloromethylaromatics with strongly electronegative substituents, for example, at least one fluorine atom, as described in Examples 1-9 in WO 2015 / 091427 on pages 19-22. Particular preference is given to using triarylalkylborates as electron donors with the benzopyrylium dyes according to the invention as the photoinitiation system. Corresponding triarylalkylborates are known from US 1,109,8066, in particular those as described on page 47 in Example 26.

[0044] Most preferably, these trialkyl borate salts are selected from the following structures, where n is chosen between 1 and 2 and K + represents any monovalent cation:

[0045]

[0046] The benzopyrylium dyes according to the invention are preferably used as part of a three-component photoinitiation system in which, in addition to the Type II photoinitiation systems described above, an electron acceptor is added. The electron acceptor is preferably selected from iodonium salts, sulfonium salts, trichlorotriazines, the trichloroaromatics described in WO 2015 / 091427, or Katritzky salts.

[0047] A further subject matter of the invention relates to a photopolymer composition comprising at least a) matrix polymers, b) writing monomers, c) a non-photopolymerizable component, d) a photoinitiator system (PIS), at least comprising a suitable co-initiator and a benzopyrylium dye according to the invention, in the form of the benzopyrylium salt of the formula (I), as well as optionally e) catalysts, radical stabilizers, solvents, additives and other auxiliaries and / or additives.

[0048] All components known to the person skilled in the art can be used as matrix polymers a), writing monomers b) and non-photopolymerizable component c) as well as PIS d). The matrix polymers a) are known, for example, from the prior art from US8921012, the writing monomers b) are known, for example, from the prior art from US2010086860, US8222314 and US10241402, the non-photopolymerizable component c) and the PIS d) are known, for example, from the prior art from US10001703 and US9146456, and the optional non-photopolymerizable component c) is known, for example, from the prior art from US8999608. All catalysts, radical stabilizers, solvents, additives and other auxiliaries and / or additives known to the person skilled in the art for this purpose can be used as optional component e).Preferred matrix polymers a) with a low refractive index are, for example, polyurethanes obtainable by reacting a polyol with a polyisocyanate component.

[0049] Preferably, the writing monomer b) comprises or consists of at least one mono- and / or one multifunctional writing monomer. More preferably, the writing monomer b) can comprise or consist of at least one mono- and / or one multifunctional (meth)acrylate writing monomer. Most preferably, the writing monomer can comprise or consist of at least one mono- and / or one multifunctional urethane (meth)acrylate.

[0050] The at least one non-photopolymerizable component c) may be any component c) that the person skilled in the art would select for the photopolymer composition according to the invention.

[0051] The at least one photoinitiator system d) can be any photoinitiator system that a person skilled in the art would select for the photopolymer composition according to the invention. Photoinitiators of component d) are typically compounds that can be activated by actinic radiation and can trigger polymerization of the writing monomers. A distinction can be made between unimolecular (type I) and bimolecular (type II) photoinitiators. Furthermore, depending on their chemical nature, they are classified as photoinitiators for radical, anionic, cationic, or mixed polymerization.

[0052] Type I photoinitiators (Norrish type I) for radical photopolymerization form free radicals upon irradiation through unimolecular bond cleavage. Examples of type I photoinitiators include triazines, oximes, benzoin ethers, benzil ketals, bisimidazoles, aroylphosphine oxides, and sulfonium and iodonium salts.

[0053] Type II photoinitiators (Norrish type II) for radical polymerization consist of a dye as a sensitizer and a coinitiator. Upon irradiation with light matched to the dye, they undergo a bimolecular reaction. Initially, the dye absorbs a photon and, from its excited state, can enter into a bimolecular reaction with a suitable coinitiator. This coinitiator releases the polymerization-initiating radicals through electron or proton transfer or direct hydrogen abstraction.

[0054] Type II photoinitiators are preferably used. Further preferred photoinitiator systems d) are described in principle in EP 0 223 587 A and preferably consist of a mixture of one or more dyes.

[0055] It is preferably provided that the photopolymer composition additionally contains urethanes as additives of component c), wherein the urethanes may in particular be substituted by at least one fluorine atom.

[0056] Likewise, the benzopyrylium dyes according to the invention can also be used in cured photopolymers which are characterized analogously to the photopolymer compositions described above. All information on the benzopyrylium dyes according to the invention, in the form of the benzopyrylium salt of the formula (I), as well as the selection of the associated anions An n- ', are to be applied analogously to the statements regarding the benzopyrylium salt of formula (I) according to the invention.

[0057] A further object of the present invention relates to a layer structure comprising at least the layers:

[0058] A. a substrate layer A., ​​which may be part of a further layer structure,

[0059] B. a photopolymer layer B., containing the photopolymer composition according to the invention, and

[0060] C. if necessary, a covering layer C., which may be part of the further layer structure.

[0061] The photopolymer composition has the same components, proportions of components, and properties as the previously described photopolymer composition according to the invention. The layer structure can comprise additional layers. Preferably, the substrate layer A and the cover layer C have an adhesive layer on at least one of the two surfaces so that the substrate layer A or the cover layer C can be bonded to the polymer layer B or another outer layer.

[0062] A further object of the present invention relates to a layer structure comprising at least the layers:

[0063] A. a substrate layer A., ​​which may be part of a further layer structure,

[0064] B. a cured photopolymer layer B', which was produced from the photopolymer composition according to the invention by curing by means of light, and

[0065] C. if necessary, a covering layer C., which may be part of the further layer structure.

[0066] The photopolymer composition has the same components, proportions of components, and properties as the previously described photopolymer composition according to the invention. The layer structure can comprise additional layers. Preferably, the substrate layer A. and the cover layer C. have an adhesive layer on at least one of the two surfaces so that the substrate layer A. or the cover layer C. can be bonded to the cured polymer layer B' or another outer layer.

[0067] The invention further relates to a holographic medium comprising a benzopyrylium dye according to the invention or a benzopyrylium dye produced by the process according to the invention or a photopolymer composition according to the invention. Also disclosed is a process for producing a holographic medium using the benzopyrylium dye according to the invention, for example in the form of the previously described photopolymer composition containing the benzopyrylium dye according to the invention. The dye according to the invention or the photopolymer compositions according to the invention can be used in particular for producing holographic media in the form of a film. The carrier used is in the form of substrate layer A.a layer of a material or material composite that is transparent to light in the visible and NIR spectral range (transmission greater than 85% in the wavelength range from 400 to 1200 nm) in the dark, coated on one or both sides with the photopolymer composition B. and, if appropriate, a cover layer C. applied to the photopolymer layer(s) B. Preferred materials or material composites of the carrier, in the form of the substrate layer A., ​​are based on polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene, polypropylene, cellulose acetate, cellulose hydrate, cellulose nitrate, cycloolefin polymers, polystyrene, polyepoxides, polysulfone, cellulose triacetate (CTA), polyamide, polyimide, polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral, or polydicyclopentadiene, or mixtures thereof. They are particularly preferably based on PC, PET, and CTA. Material composites can be film laminates or coextrudates.Preferred material composites are duplex and triplex films constructed according to one of the schemes A. / B., A. / B. / A. or A. / B. / C.. PC / PET, PET / PC / PET and PC / TPU (TPU = thermoplastic polyurethane) are particularly preferred. The materials or material composites of the carrier, in the form of substrate layer A., ​​can be made non-adhesive, antistatic, hydrophobic or hydrophilic on one or both sides. The materials or material composites can also be activated primarily by plasma pretreatment or UV light irradiation. The aforementioned modifications on the side facing the photopolymer layer B serve the purpose of ensuring that the photopolymer layer B either adheres more strongly to the substrate layer A. or, conversely, can be removed from the substrate layer A. without damage. A modification of the side of the carrier, in the form of substrate layer A, facing away from the photopolymer layer B.serves to ensure that the media according to the invention meet specific mechanical requirements, for example, those required for processing in roll laminators, particularly in roll-to-roll processes. The cover layer C preferably has the same materials, properties, and composition as the substrate layer A and is preferably produced in the same way as the substrate layer A.

[0068] In addition, a further process for producing a holographic medium using a benzopyrylium dye according to the invention, in particular in the form of the previously described photopolymer composition containing at least the benzopyrylium dye, is disclosed, which likewise yields holographic media in the form of films or layer structures. In this case, as substrate layer A., ​​a layer of a material or material composite transparent to light in the visible and NIR spectral range (transmission greater than 85% in the wavelength range from 400 to 1200 nm) is applied in the dark with the photopolymer composition B. on one side by means of 2D printing and, if appropriate, a cover layer C. on the photopolymer layer(s) B. All common inkjet technologies can be used. If necessary, only the areas required for the function can be specifically printed with the photopolymer composition B.Preferred materials or material composites for the carrier are based on glass, silicon (in the form of the highly polished wafers known from semiconductor technology), polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene, polypropylene, cellulose acetate, cellulose hydrate, cellulose nitrate, cycloolefin polymers, polystyrene, polyepoxides, polysulfone, cellulose triacetate (CTA), polyamide, polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral, or polydicyclopentadiene, or mixtures thereof. They are particularly preferably based on PC, PET, and CTA. Material composites can be film laminates or coextrudates. Preferred material composites are duplex and triplex films constructed according to one of the schemes A. / B., A. / B. / A., or A. / B. / C. PC / PET, PET / PC / PET, and PC / TPU (TPU = thermoplastic polyurethane) are particularly preferred.The materials or material composites of the carrier can be made non-adhesive, antistatic, hydrophobic, or hydrophilic on one or both sides. The aforementioned modifications on the side facing the photopolymer layer B serve to ensure that the photopolymer layer B can be removed non-destructively from the carrier in the form of the substrate layer A. A modification of the side of the carrier facing away from the photopolymer layer B serves to ensure that the media according to the invention meet specific mechanical requirements, which are required, for example, for processing in roll laminators, particularly in roll-to-roll processes.

[0069] Also preferred are material composites of the type described above, comprising a light-cured photopolymer layer B', resulting in duplex and triplex films according to a scheme A. / B'., A. / B'. / A. or A. / B'. / C.

[0070] In addition, a further process for producing a holographic medium using a benzopyrylium dye according to the invention, in particular in the form of the previously described photopolymer composition comprising at least the benzopyrylium dye, is disclosed, which likewise yields holographic media in the form of a glass (D.) or acrylic (E.) composite. The photopolymer composition is embedded in the dark directly between two glass or acrylic layers. This is preferably carried out by a method selected from the group consisting of injecting the photopolymer composition into a cavity of two glass or acrylic surfaces, by applying it to a glass or acrylic surface by spraying, doctor blade coating, dip coating, die coating, roller coating, or spin coating, or by laminating a free photopolymer film and covering it with a second glass or acrylic surface. Preference is given to a D. / B. / D., D. / B. / E., E. / B. / D., E. / B. / E., D. / B. / A. or E. / B. / A.Layer structure, where D. here stands for a glass layer and E. for an acrylic layer. The layers D. and E. are preferably non-adhesive, hydrophobic or hydrophilic. The modifications mentioned serve the purpose on the side facing the photopolymer layer B. so that the photopolymer layer B. either adheres more strongly to the surfaces of D. or E. or, on the contrary, can be removed from the surface without damage. Also preferred are glass or acrylic composites of the type described above, comprising a light-cured photopolymer layer B'., resulting in a composite according to the scheme D. / B'. / D., D. / B'. / E., E. / B'. / D., E. / B'. / E., D. / B'. / A. or E. / B'. / A.

[0071] Holographic information can be imprinted into such holographic media in the form of a hologram.

[0072] The holographic media according to the invention can be processed into holograms for optical applications in the NIR and the entire visible and near-UV range (350-1500 nm) by appropriate exposure processes. Holograms include all holograms that can be recorded using methods known to those skilled in the art.

[0073] The invention further relates to a hologram obtainable from the holographic medium according to the invention. As described above, the hologram is obtained by appropriately exposing the holographic medium.

[0074] A preferred embodiment of the hologram is selected from the group consisting of off-axis holograms, full-aperture transfer holograms, white-light transmission holograms ("rainbow holograms"), Denisyuk holograms, off-axis reflection holograms, edge-lit holograms, and holographic stereograms. Preference is given to reflection holograms, Denisyuk holograms, transmission holograms, or a combination of at least two thereof. Preferably, combinations of these hologram types or multiple holograms of the same type are combined independently of one another in the same volume of the holographic medium, also known as multiplexing.

[0075] Possible optical functions of the holograms that can be produced with the photopolymer compositions containing at least one benzopyrylium dye according to the invention correspond to the optical functions of light elements such as lenses, mirrors, deflecting mirrors, filters, diffraction screens, diffraction elements, diffusers, waveguides, light guides, projection screens, and / or masks. Combinations of these optical functions can also be combined independently of one another in a hologram. These optical elements often exhibit frequency selectivity, depending on how the holograms were exposed and the dimensions of the hologram.

[0076] In addition, holographic media can also be used to create holographic images or representations in the form of a hologram, for example, for personal portraits, biometric representations in security documents, or generally for images or image structures for advertising, security labels, trademark protection, brand branding, labels, design elements, decorations, illustrations, trading cards, pictures, and the like, as well as images that can represent digital data, including in combination with the previously described products. Holographic images can have the impression of a three-dimensional image, but they can also represent image sequences, short films, or a number of different objects, depending on the angle, the light source (including moving ones), etc., from which they are illuminated.

[0077] Another subject of the invention relates to an optical display comprising a holographic medium according to the invention or a hologram according to the invention.

[0078] Another object of the invention relates to the use of the photopolymer composition according to the invention for producing a holographic medium or a hologram.

[0079] The above-described functions of the holograms that can be produced with the benzopyrylium dye according to the invention or the photopolymer compositions according to the invention are used, for example, but not exclusively, in the fields of eye tracking, sensor technology, as well as LIDAR and augmented reality, head-mounted display and virtual reality applications in the NIR range.

[0080] A further subject matter of the invention relates to a use of a holographic medium according to the invention for producing chip cards, identity documents, 3D images, product protection labels, labels, banknotes or holographic optical elements, in particular for optical displays or in media for implementing methods selected from the group consisting of eye tracking, sensor technology, LIDAR, augmented reality, head-mounted display, head-up display and virtual reality applications, in particular in the near infrared range and a combination of at least two thereof.

[0081] The holographic media can be used to record in-line, off-axis, full-aperture transfer, white light transmission, Denisyuk, off-axis reflection or edge-lit holograms as well as holographic stereograms, in particular for the production of optical elements, images or image representations.

[0082] Holograms are preferably accessible from holographic media according to the invention by exposure.

[0083] Examples:

[0084] The following examples serve to illustrate the invention without limiting it to them.

[0085] Measurement methods:

[0086] OH number: The stated OH numbers were determined according to DIN 53240-2-2007-11.

[0087] NCO value: The stated NCO values ​​(isocyanate contents) were determined according to DIN EN ISO 11909-2007-05. Measurement of the holographic properties DE and Δn of the holographic media using

[0088] Two-beam interference in reflection arrangement:

[0089] The beam of a blue DPSS laser with an emission wavelength λ of 457 nm in vacuum was converted into a parallel, homogeneous beam using a spatial filter (SF) and a collimating lens (CL), as shown in Figure 1. The final cross-sections of the signal and reference beams were determined by the iris diaphragms (I). The diameter of the iris diaphragm opening was 0.4 cm. The polarization-dependent beam splitters (PBS) split the laser beam into two coherent, equally polarized beams. The power of the reference beam was set to 0.5 mW and the power of the signal beam to 0.65 mW using the λ / 2 plates. The powers were determined using the semiconductor detectors (D) with the sample removed. The angle of incidence (α0) of the reference beam was -22.0°, and the angle of incidence (β0) of the signal beam was 42.0°. The angles were measured from the sample normal to the beam direction.According to Figure 1, α0 therefore had a negative sign and β0 a positive sign. At the location of the sample (holographic medium), the interference field of the two overlapping beams created a grating of bright and dark fringes perpendicular to the angle bisector of the two beams incident on the sample (reflection hologram). The fringe spacing A, also called the grating period, in the holographic medium was ~225 nm (the refractive index of the holographic medium was assumed to be ~1.504).

[0090] Figure 1 shows the holographic experimental setup used to measure the diffraction efficiency (DE) of holographic media. Figure 1 depicts the geometry of a Holographic Media Tester (HMT) at λ = 457 nm (DPSS laser): M = mirror, S = shutter, SF = spatial filter, CL = collimator lens, λ / 2 = λ / 2 plate, PBS = polarization-sensitive beam splitter, D = detector, I = iris diaphragm, α0 = -22°, β0 = 42° are the angles of incidence of the coherent beams measured outside the sample (the holographic medium). RD = reference direction of the turntable.

[0091] Holograms were written into the holographic medium in the following way:

[0092] • Both shutters (S) are open for the exposure time t.

[0093] • Afterwards, with the shutters closed (S), the holographic medium was allowed 5 minutes for the diffusion of the not yet polymerized writing monomers.

[0094] The written holograms were then read out as follows: The shutter of the signal beam remained closed. The shutter of the reference beam was open. The iris of the reference beam was closed to a diameter of < 1 mm. This ensured that for all rotation angles (Ω) of the holographic medium, the beam always lay completely within the previously written hologram. The turntable then covered the angular range of Ω under computer control. min to Ω max with an angular step size of 0.05°. Ω was measured from the sample normal to the reference direction of the turntable. The reference direction of the turntable was determined when the angle of incidence of the reference and signal beams was equal during the hologram writing process, i.e., α0 = -32° and β0 = 32°. Then, Ω was recording = 0°. For α0= -22.0° and β0= 42.0°, Ω was recording hence 10°. In general, the interference field during recording of the hologram was: θ0 was the half-angle in the laboratory system outside the holographic medium and the following applied when writing the hologram:

[0095] In this case, θ0 = -32°. At each angle of rotation Ω, the power of the beam transmitted in the zeroth order was measured using the corresponding detector D, and the power of the beam diffracted into the first order was measured using the detector D. The diffraction efficiency p was determined at each angle Ω as the quotient of:

[0096] PD is the power in the detector of the diffracted beam and PT is the power in the detector of the transmitted beam.

[0097] Using the method described above, the Bragg curve of the written hologram, which describes the diffraction efficiency η as a function of the rotation angle Ω, was measured and stored in a computer. In addition, the intensity transmitted to the zeroth order was plotted against the rotation angle Ω and stored in a computer.

[0098] The maximum diffraction efficiency (DE = η max ) of the hologram, i.e. its peak value, was measured at Ω reconstruction It may have been necessary to change the position of the detector of the diffracted beam to determine this maximum value.

[0099] The refractive index contrast Δn and the thickness d of the photopolymer layer (i.e., the sample or holographic medium) were then determined using the coupled wave theory (see H. Kogelnik, The Bell System Technical Journal, Volume 48, November 1969, Number 9, pages 2909 - 2947) from the measured Bragg curve and the angular distribution of the transmitted intensity. It should be noted that due to the thickness shrinkage occurring during photopolymerization, the fringe spacing Λ' of the hologram and the orientation of the fringe (slant) may deviate from the fringe spacing A of the interference pattern and its orientation. Accordingly, the angle α0' or the corresponding angle of the rotary table Ω reconstruction , at which maximum diffraction efficiency is achieved from α0 or from the corresponding Ω recordingThis changes the Bragg condition. This change is taken into account in the evaluation procedure. The evaluation procedure is described below: All geometric quantities that refer to the written hologram and not to the interference pattern are represented by primed quantities.

[0100] According to Kogelnik, the Bragg curve η(Ω) of a reflection hologram is: with:

[0101] (6)

[0102] (7)

[0103] (8)

[0104] (9)

[0105] (10)

[0106] (11)

[0107] (12)

[0108] When reading the hologram (“reconstruction”), the following applies as shown above: (13) (14)

[0109] At the Bragg condition, the dephasing is DP = 0. And it follows accordingly:

[0110] (15)

[0111] (16)

[0112] The still unknown angle β' can be determined by comparing the Bragg condition of the interference field during writing the hologram and the Bragg condition during reading the hologram, assuming that only thickness shrinkage occurs. Then it follows: (17) v is the grating thickness, ξ is the detuning parameter, and ψ' is the orientation (slant) of the refractive index grating that was written. α' and β' correspond to the angles α0 and β0 of the interference field during writing of the hologram, but measured in the holographic medium and valid for the grating of the hologram (after thickness shrinkage). n is the average refractive index of the photopolymer and was set to 1.504. λ is the wavelength of the laser light in vacuum.

[0113] The maximum diffraction efficiency (DE = η max ) then results for E, = 0 to:

[0114] (18)

[0115] The measured data of the diffraction efficiency, the theoretical Bragg curve and the transmitted intensity are plotted against the centered rotation angle ΔΩ = Ω as shown in Figure 2 reconstruction — Ω — a'0— ϑ'0, also called angle detuning (x-axis). Figure 2 shows the measured transmitted power P T (right y-axis) plotted as a solid line (here of example 5) against the angle detuning ΔΩ, the measured diffraction efficiency η (left y-axis) plotted as filled circles against the angle detuning ΔΩ (as far as the finite size of the detector allowed) and the fit of the Kogelnik theory as a dashed line (left y-axis).

[0116] Since DE is known, the shape of the theoretical Bragg curve according to Kogelnik is determined solely by the thickness d' of the photopolymer layer. Δn is corrected via DE for a given thickness d' such that the measurement and theory of DE always agree. d' is then adjusted until the angular positions of the first secondary minima of the theoretical Bragg curve agree with the angular positions of the first secondary maxima of the transmitted intensity, and the full width at half height (FWHM) for the theoretical Bragg curve and the transmitted intensity agree.

[0117] Since the direction in which a reflection hologram rotates during reconstruction using an Ω-scan is limited, and the detector for the diffracted light can only capture a finite angular range, the Bragg curve of wide holograms (small d') is not completely captured in an Ω-scan, but only the central region with appropriate detector positioning. Therefore, the shape of the transmitted intensity complementary to the Bragg curve is also used to adjust the layer thickness d'.

[0118] Figure 2 shows the Bragg curve η according to the coupled wave theory (dashed line), the measured diffraction efficiency (filled circles) and the transmitted power (black solid line) versus the angle detuning ΔΩ. For one formulation, this procedure may have been repeated several times for different exposure times t on different holographic media in order to determine at which average energy dose of the incident laser beam reaches the saturation value when writing the hologram DE. The average energy dose E is calculated as follows from the powers of the two partial beams assigned to the angles α0 and β0 (reference beam with P r = 1.31 mW and signal beam with P s = 1.69 mW), the exposure time t and the diameter of the iris diaphragm (0.4 cm):

[0119] (19)

[0120] The powers of the partial beams were adjusted so that the same power density is achieved in the holographic medium at the used angles α0 and β0.

[0121] Substances:

[0122] The solvents, reagents, and all bromoaromatics used were purchased from chemical retailers. The bromoaromatics were freshly distilled where necessary. Anhydrous solvents contain < 50 ppm water.

[0123] Polyol 1 was prepared as described for Polyol 1 in WO2015091427 with an OH number of 56.8.

[0124] Desmodur® N 3900 product of Covestro AG, Leverkusen, DE, hexane diisocyanate-based polyisocyanate, iminooxadiazinedione content at least 30%, NCO content: 23.5%.

[0125] Fomrez® UL-28 urethanization catalyst, commercial product of Momentive

[0126] Performance Chemicals, Wilton, CT, USA.

[0127] Urethane acrylate 1 (phosphorothioyltris(oxybenzene-4,1-diylcarbamoyloxyethane-2,1-diyl)trisacrylate, [CAS No. 1072454-85-3]) was prepared as described in WO2015091427.

[0128] Urethane acrylate 2 (2-({[3-(methylsulfanyl)phenyl]carbamoyl}oxy)-ethylprop-2-enoate, [CAS No. 1207339-61-4]) was prepared as described in WO2015091427.

[0129] Additive 1 (bis(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl)-(2,2,4-trimethylhexane-l,6-diyl)biscarbamate, [CAS No. 1799437-41-4]) was prepared as described in WO2015091427.

[0130] Coinitiator 1 (A-benzyl-A,A-dimethylhexadecylammonium tris-(3-chloro-4-methylphenyl)hexylborate, [CAS No. 1702465-82-4]) was prepared as described in WO2018087064 from l-bromo-3-chlorobenzene, diisopropylhexylboronic acid ester and N-benzyl-N,N-dimethylhexadecylammonium chloride.

[0131] BYK-310 Silicone-containing surface additive, product of BYK-Chemie GmbH,

[0132] Wesel, Germany.

[0133] Dye 1 Benzopyrylium dye 5,6-Dihydro-3,10-dimethoxy-7-phenylbenzo-

[0134] [c]xanthylium perchlorate [CAS No. 126634-30-8], supplied by Synthon Chemicals GmbH & Co.KG, Bitterfeld-Wolfen, Germany.

[0135] Dye 2 (1,3,3-trimethyl-2-[2-(l-methyl-2-phenyl-lH-indol-3-yl)ethenyl]-3H-indoliumbis(2-ethylhexyl)sulfobsuccinic acid ester)) [CAS No. 1374689-54-9] was prepared as described in WO2012062655.

[0136] Dye 3 2-[2-[4-[(2-chloroethyl)methylamino]phenyl]ethenyl]- 1,3,3-trimethyl-

[0137] 3 / / -indoliumbis(2-ethylhexyl)sulfobuccinic acid ester)) [CAS No. 153952-28-4] was prepared as described in WO2012062655.

[0138] Synthesis instructions:

[0139] Preparation procedure A (for benzopyrylium salts with R 200 , R 204 , R 205 , R 207 and R 208 = H and any R 201except NR2):

[0140] The corresponding 2-hydroxyarylaldehyde derivative (1.0 eq.) was dissolved together with the corresponding tetralone derivative (1.0 eq.) in glacial acetic acid (0.4 M). Sulfuric acid (2.0 eq.) was slowly added, and the mixture was heated at reflux for 1 h. After cooling to room temperature, the reaction solution was added to methyl tert-butyl ether (MTBE). The resulting solid was filtered off, and the reaction product was washed with MTBE (2x) and dried in vacuo. The reaction product was then dissolved in a butyl acetate / water mixture (1:1) at 50 °C together with the corresponding sodium salt of the dye anion (1.0 eq.) and stirred vigorously overnight. The phases were separated, and the organic phase was washed with water (deionized, 6x). After removal of the solvent in vacuo and drying of the residue in vacuo, the product was obtained as a highly viscous oil. Preparation procedure B (for benzopyrylium bis-(2-ethylhexyl)sulfosuccinic acid ester with R 200 ,

[0141] R 203 , R 205 , R 207 and R 208 = H and R 204 = Ph):

[0142] The corresponding 2-hydroxybenzophenone derivative (1.0 eq.) is dissolved together with the corresponding tetralone derivative (1.0 eq.) in glacial acetic acid (0.4 M). Sulfuric acid (2.0 eq.) is slowly added, and the mixture is heated at reflux for at least 8 h. After cooling to room temperature, the reaction solution is added to methyl tert-butyl ether (MTBE), which separates the product as an insoluble oil. The ether phase is separated, and the oily phase is washed several times with MTBE. The product is dissolved together with sodium bis-(2-ethylhexyl)sulfosuccinic acid ester at 50 °C in a butyl acetate / water mixture (1:1) and stirred vigorously overnight. The phases are separated, and the organic phase is washed with water (deionized, 6 times). After removal of the solvent in vacuo and drying of the residue in vacuum, the product is obtained as a highly viscous oil.

[0143] Preparation C (for Benzopyrylium bis-(2-ethylhexyl)sulfosuccinic acid ester with R200 , R 202 R 203 R 204 R 205 R 20 7 u nd R 208 = H und R 201 = NE t2 ).

[0144] 4-Diethylaminosalicylaldehyde (1.0 eq.) is dissolved together with the corresponding tetralone derivative (1.0 eq.) in glacial acetic acid (0.4 M). Sulfuric acid (2.0 eq.) is slowly added, and the mixture is heated at reflux for 1 h. After cooling to room temperature, the reaction solution is added to methyl tert-butyl ether (MTBE), which separates the product as an insoluble oil. The ether phase is separated, and the product is taken up in deionized water. The aqueous phase is washed with MTBE (3 x) and finally stirred vigorously overnight with a butyl acetate solution of sodium bis(2-ethylhexyl)sulfosuccinic acid ester (0.9 eq.), forming a two-phase mixture. The phases are separated, and the organic phase is washed with deionized water (6 x). After removal of the solvent in vacuo and drying of the residue in vacuum, the product is obtained.

[0145] Preparation Instructions D (for photopolymer film / holographic media): 5.85 g of the polyol component 1 described above were melted and mixed in the dark with 2.16 g of urethane acylate 1, 6.48 g of urethane acrylate 2 described above, 5.4 g of the fluorinated urethane (additive 1) described above, 0.43 g of coinitiator 1 described above, 0.11 g of the respective dye, 0.07 g of BYK 310, 0.02 g of Fomrez® UL-28, and 8.4 g of ethyl acetate to obtain a clear solution. Subsequently, 1.08 g of Desmodur® N 3900 were added and mixed again. This solution was applied to a 60 μm thick TAC film in a roll-to-roll coating system in the dark and applied using a doctor blade to achieve a wet film thickness range of 12-14 μm. The coated film was dried at a drying temperature of 120 °C and a drying time of 4 minutes and then protected with a 40 μm thick polyethylene film.This film was then packaged in a light-tight manner.

[0146] Examples

[0147] Example 1: Preparation of 12,13-dihydro-10-methoxydibenzo[a,h]xanthylium bis-(2-ethylhexyl)- sulfosuccinic acid ester and preparation of the holographic medium containing 12,13-dihydro-10-methoxydibenzo|a,h ]xanthylium bis-(2-ethylhexyl) sulfosuccinic acid ester:

[0148] Following general preparation procedure A, 2-hydroxynaphthaldehyde was reacted with 6-methoxy-l-tetralone, and sodium bis(2-ethylhexyl)sulfosuccinic acid ester was used for ion exchange. A red, highly viscous oil (1.81 g, 72% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared following preparation procedure D.

[0149] ' H NMR (600 MHz, CDCl3): δ 10.39 (s, 1H), 9.18 (d, J = 8.4 Hz, 1H), 8.44 (d, J = 9.2 Hz, 1H), 8.36 (d, J = 8.8 Hz, 1H), 8.06 (ddd, J = 11.0, 7.5, 2.0 Hz, 2H), 7.99 (d, J= 9.2 Hz, 1H), 7.83 (ddd, J = 8.1, 7.0, 1.0 Hz, 1H), 7.12 - 7.07 (m, 1H), 6.96 (d, J = 2.4 Hz, 1H), 4.25 - 4.20 (m, 1H), 4.03 - 3.87 (m, 7H), 3.71 (t, J = 7.5 Hz, 2H), 3.34 - 3.25 (m, 3H), 3.14 (dd, J = 17.6, 3.3 Hz, 1H), 1.54 - 1.48 (m, 2H), 1.34 - 1.17 (m, 16H), 0.91 - 0.79 (m, 12H).

[0150] Absorption maximum (in acetone): 479 - 490 nm.

[0151] Example 2: Preparation of 5,6-dihydro-3,9,10-trimethoxybenzo[c]xanthylium bis-(2-ethylhexyl)- sulfosuccinic acid ester and preparation of the holographic medium containing 5,6-dihydro-3,9,10-trimethoxybenzo[c]xanthylium bis-(2-ethylhexyl) sulfosuccinic acid ester:

[0152] According to general preparation procedure A, 2-hydroxy-4,5-dimethoxybenzaldehyde was reacted with 6-methoxy-l-tetralone, and sodium bis(2-ethylhexyl)sulfosuccinic acid ester was used for ion exchange. An orange, highly viscous oil (2.3 g, 90% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared according to preparation procedure D. 1 H NMR (600 MHz, CDCl3): δ 9.17 (s, 1H), 8.45 (d, J = 8.8 Hz, 1H), 7.70 (d, J = 9.8 Hz, 2H), 7.10 (dd, J = 8.8, 2.5 Hz, 1H), 6.86 (d, .7 = 2.4 Hz, 1H), 4.23 (dd, J= 11.7, 3.4 Hz, 1H), 4.14 (s, 3H), 4.01 - 3.91 (m, 10H), 3.34 - 3.24 (m, 3H), 3.17 - 3.08 (m, 3H), 1.53 (pd, J= 6.0, 1.9 Hz, 2H), 1.36 - 1.19 (m, 16H), 0.90 - 0.80 (m, 12H).

[0153] Absorption maximum (in acetone): 480 - 492 nm.

[0154] Example 3: Preparation of 10-(Diethylamino)-5,6-dihydro-3-methoxybenzo[c1xanthyliumbis-(2-ethyl-hexyl)sulfosuccinic acid ester and preparation of the holographic medium containing 10-(Diethylamino)-5,6-dihydro-3-methoxybenzo[c1xanthyliumbis-(2-ethyl-hexyl)sulfosuccinic acid ester:

[0155] 6-Methoxy-l-tetralone was reacted according to general preparation procedure C. A violet, highly viscous oil (1.2 g, 76% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared according to preparation procedure D.

[0156] 1H NMR (600 MHz, CDCl3): δ 8.98 (s, 1H), 8.24 (d, J = 9.4 Hz, 1H), 8.17 (d, J = 8.8 Hz, 1H), 7.22 (dd, J = 9.4, 2.5 Hz, 1H), 7.00 (dd, J = 8.8, 2.5 Hz, 1H), 6.91 (dd, J= 2.4, 0.8 Hz, 1H), 6.86 (d, J= 2.4 Hz, 1H), 4.22 (dd, J= 11.9, 3.1 Hz, 1H), 4.06 (s, 7H), 3.64 (q, J= 7.2 Hz, 4H), 3.38 (dd, J= 17.6, 12.0 Hz, 1H), 3.24 - 3.16 (m, 3H), 3.07 (dd, J= 8.8, 6.5 Hz, 2H), 1.57 - 1.48 (m, 2H), 1.38 - 1.18 (m, 22H), 0.89 - 0.83 (m, 12H).

[0157] Absorption maximum (in acetone): 543 - 572 nm.

[0158] Example 4: Preparation of 10-(Diethylamino)-5,6-dihydrobenzo[c]xanthyliumbis-(2-ethylhexyl)- sulfosuccinic acid ester and preparation of the holographic medium containing 10-(Diethylamino)-5,6-dihydrobenzo[c~|xanthyliumbis-(2-ethylhexyl)sulfosuccinic acid ester:

[0159] 1-Tetralone was reacted according to general preparation procedure C. A violet, highly viscous oil (1.4 g, 64% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared according to preparation procedure D.

[0160] 1 H NMR (600 MHz, CDCl3): δ 8.93 (s, 1H), 8.22 (d, J= 9.5 Hz, 1H), 8.16 (dd, J= 7.8, 1.3 Hz, 1H), 7.52 (td, J= 7.5, 1.4 Hz, 1H), 7.46 (td, J= 7.6, 1.2 Hz, 1H), 7.32 (dd, J= 7.6, 1.2 Hz, 1H), 7.28 (dd, J = 9.4, 2.4 Hz, 1H), 6.96 - 6.91 (m, 1H), 4.19 (dd, J= 11.9, 3.2 Hz, 1H), 4.04 (s, 4H), 3.66 (q, J= 7.2 Hz, 4H), 3.31 (dd, J= 17.6, 11.9 Hz, 1H), 3.20 - 3.11 (m, 3H), 3.06 (dd, J= 8.9, 6.6 Hz, 2H), 1.55 - 1.46 (m, 2H), 1.36 - 1.16 (m, 22H), 0.89 - 0.76 (m, 12H).

[0161] Absorption maximum (in acetone): 527 - 554 nm. Example 5: Preparation of 5,6-dihydro-3,10-dimethoxy-7-phenylbenzo[c]xanthylium bis-(2-ethylhexyl)sulfobsuccinic acid ester and preparation of the holographic medium containing 5,6-dihydro-3,10-dimethoxy-7-phenylbenzo[c]xanthylium bis-(2-ethylhexyl)sulfobsuccinic acid ester:

[0162] Following general preparation procedure B, 2-hydroxy-4-methoxybenzophenone was reacted with 6-methoxy-l-tetralone for 22 h at 140 °C. A dark red solid (1.8 g, 76% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared following preparation procedure D.

[0163] 'H NMR (600 MHz, CDCl3): δ 8.74 (d, J= 8.9 Hz, 1H), 8.00 (d, 7 2.4 Hz, 1H), 7.65 - 7.61 (m, 3H), 7.42 (d, J= 9.2 Hz, 1H), 7.41 - 7.38 (m, 2H), 7.18 (ddd, J= 9.2, 4.5, 2.5 Hz, 2H), 6.85 (d, J= 2.4 Hz, 1H), 4.19 - 4.10 (m, 4H), 4.03 - 3.88 (m, 7H), 3.24 - 3.16 (m, 1H), 3.06 - 3.00 (m, 4H), 2.95 - 2.90 (m, 1H), 1.54 - 1.48 (m, 2H), 1.38 - 1.18 (m, 16H), 0.91 - 0.80 (m, 12H).

[0164] Absorption maximum (in acetone): 471 - 481 nm.

[0165] Example 6: Preparation of 5,6-dihydro-3,10-dimethoxybenzo[c]xanthylium bis-(2-ethylhexyl)-sulfobsuccinic acid ester and preparation of the holographic medium containing 5,6-dihydro-3,10-dimethoxybenzo[c]xanthylium bis-(2-ethylhexyl)-sulfobsuccinic acid ester:

[0166] Following general preparation procedure A, 4-methoxysalicylaldehyde was reacted with 6-methoxy-l-tetralone, and sodium bis(2-ethylhexyl)sulfosuccinic acid ester was used for ion exchange. A red solid (2.0 g, 74% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared following preparation procedure D.

[0167] II NMR (600 MHz, CDCl3): δ 9.21 (s, 1H), 8.48 (d, J= 8.9 Hz, 1H), 8.16 (d, J= 9.0 Hz, 1H), 7.69 (d, J= 2.3 Hz, 1H), 7.19 (dd, J= 9.0, 2.3 Hz, 1H), 7.09 (dd, J= 8.9, 2.5 Hz, 1H), 6.85 (d, J= 2.4 Hz, 1H), 4.21 (dd, 7 = 11.8, 3.3 Hz, 1H), 4.09 - 3.89 (m, 10H), 3.35 - 3.24 (m, 3H), 3.17 - 3.07 (m, 3H), 1.57 - 1.48 (m, 2H), 1.34 - 1.17 (m, 16H), 0.89 - 0.79 (m, 12H).

[0168] Absorption maximum (in acetone): 466 - 479 nm.

[0169] Example 7: Preparation of 5,6-dihydro-3-methoxy-9-methyl-7-phenylbenzo[c]xanthylium bis-(2-ethylhexyl)sulfosuccinic acid ester and preparation of the holographic medium containing 5,6-dihydro-3-methoxy-9-methyl-7-phenylbenzo[c]xanthylium bis-(2-ethylhexyl)sulfosuccinic acid ester:

[0170] Following general preparation procedure B, 2-hydroxy-5-methylbenzophenone was reacted with 6-methoxy-l-tetralone for 12 h. A brown solid (0.98 g, 35% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared following preparation procedure D. 'H NMR (600 MHz, CDCl3): δ 8.60 (d, J= 8.9 Hz, 1H), 8.21 (d, J= 8.7 Hz, 1H), 7.87 (dd, J= 8.7, 2.0 Hz, 1H), 7.68 - 7.61 (m, 3H), 7.48 - 7.43 (m, 2H), 7.29 (dd, J= 2.1, 1.0 Hz, 1H), 7.14 (dd, J= 9.0, 2.4 Hz, 1H), 6.96 (d, J= 2.4 Hz, 1H), 4.02 - 3.83 (m, 8H), 3.20 - 3.12 (m, 3H), 3.04 (dd, J= 8.2, 6.0 Hz, 2H), 2.95 (dd, J= 17.5, 2.9 Hz, 1H), 2.45 (s, 3H), 1.52 - 1.45 (m, 2H), 1.32 - 1.17 (m, 16H), 0.87 - 0.79 (m, 12H).

[0171] Absorption maximum (in acetone): 455 - 464 nm.

[0172] Example 8: Preparation of 5,6-dihydro-3-methoxy-10-methylbenzo[c]xanthylium bis-(2-ethylhexyl)-sulfobsuccinic acid ester and preparation of the holographic medium containing 5,6-dihydro-3-methoxy-10-methylbenzo[c]xanthylium bis-(2-ethylhexyl)-sulfobsuccinic acid ester:

[0173] According to general preparation procedure A, 2-hydroxy-4-methylbenzaldehyde was reacted with 6-methoxy-l-tetralone, and sodium bis(2-ethylhexyl)sulfosuccinic acid ester was used for ion exchange. A brown, highly viscous oil (1.7 g, 66% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared according to preparation procedure D.

[0174] 1H NMR (600 MHz, CDCl3): δ 9.56 (d, J= 1.0 Hz, 1H), 8.33 (dd, J= 8.6, 6.0 Hz, 2H), 7.82 (d, J= 1.5 Hz, 1H), 7.63 - 7.59 (m, 1H), 7.08 (dd, J= 8.9, 2.5 Hz, 1H), 6.95 (dd, J= 2.4, 1.1 Hz, 1H), 4.17 (ddd, J= 11.8, 3.3, 0.7 Hz, 1H), 4.05 - 3.88 (m, 7H), 3.50 - 3.46 (m, 2H), 3.30 - 3.20 (m, 3H), 3.10 (dd, J = 17.5, 3.3 Hz, 1H), 2.68 (s, 3H), 1.58 - 1.49 (m, 2H), 1.35 - 1.20 (m, 16H), 0.90 - 0.82 (m, 12H).

[0175] Absorption maximum (in acetone): 458 - 463 nm.

[0176] Example 9: Preparation of 12,13-Dihydrodibenzo[a,h]xanthyliumbis-(2-ethylhexyl)sulfobuccinic acid ester and preparation of the holographic medium containing 12,13-Dihydrodibenzo[a,h]xanthylium-bis-(2-ethylhexyl)sulfobuccinic acid ester:

[0177] According to general preparation procedure A, 2-hydroxynaphthaldehyde was reacted with 1-tetralone, and sodium bis(2-ethylhexyl)sulfosuccinic acid ester was used for ion exchange. An orange solid (0.84 g, 49% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared according to preparation procedure D.

[0178] 1 H NMR (600 MHz, CDCl3): δ 10.71 (s, 1H), 9.28 (d, J= 8.3 Hz, 1H), 8.54 (d, J= 9.2 Hz, 1H), 8.37 (dd, J= 7.9, 1.2 Hz, 1H), 8.12 - 8.03 (m, 3H), 7.85 (ddd, J= 8.1, 7.1, 1.0 Hz, 1H), 7.73 (td, J= 7.5, 1.3 Hz, 1H), 7.62 - 7.56 (m, 1H), 7.49 (d, J= 7.6 Hz, 1H), 4.23 - 4.19 (m, 1H), 4.04 - 3.88 (m, 4H), 3.77 (dd, J= 8.3, 6.9 Hz, 2H), 3.34 - 3.25 (m, 3H), 3.13 (dd, J= 17.5, 3.3 Hz, 1H), 1.52 (p, J= 5.7 Hz, 2H), 1.34 - 1.16 (m, 16H), 0.91 - 0.78 (m, 12H).

[0179] Absorption maximum (in acetone): 460 - 462 nm. Example 10: Preparation of 5,6-dihydro-3-methoxy-7-phenylbenzo[c]xanthylium bis-(2-ethylhexyl~)-sulfosuccinic acid ester and preparation of the holographic medium containing 5,6-dihydro-3-methoxy-7-phenylbenzo[c]xanthylium bis-(2-ethylhexyl)-sulfosuccinic acid ester:

[0180] According to general preparation procedure B, 2-hydroxybenzophenone was reacted with 6-methoxy-l-tetralone for 8 h. A dark orange, highly viscous oil (0.84 g, 27% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared according to preparation procedure D.

[0181] 'H NMR (600 MHz, CDCl3): δ 8.65 (d, J= 8.9 Hz, 1H), 8.31 (d, J= 8.5 Hz, 1H), 8.07 (ddd, J= 8.6, 7.0, 1.5 Hz, 1H), 7.69 - 7.61 (m, 4H), 7.59 (dd, J = 8.3, 1.4 Hz, 1H), 7.50 - 7.46 (m, 2H), 7.19 (dd, J = 8.9, 2.4 Hz, 1H), 6.97 (d, J = 2.3 Hz, 1H), 4.12 - 4.05 (m, 1H), 4.05 - 3.85 (m, 7H), 3.18 - 3.06 (m, 5H), 2.98 - 2.92 (m, 1H), 1.54 - 1.47 (m, 2H), 1.36 (s, 16H), 0.91 - 0.80 (m, 12H).

[0182] Absorption maximum (in acetone): 455 - 463 nm.

[0183] Example 11: Preparation of 5,6-dihydro-3-methoxy-9-methylbenzo[c]xanthylium bis-(2-ethylhexyl)-sulfobsuccinic acid ester and preparation of the holographic medium containing 5,6-dihydro-3-methoxy-9-methylbenzo[c]xanthylium bis-(2-ethylhexyl)-sulfobsuccinic acid ester:

[0184] According to general preparation procedure A, 2-hydroxy-5-methylbenzaldehyde was reacted with 6-methoxy-l-tetralone, and sodium bis(2-ethylhexyl)sulfosuccinic acid ester was used for ion exchange. A brown solid (2.2 g, 86% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared according to preparation procedure D.

[0185] II NMR (600 MHz, CDCl3): δ 9.51 (d, J= 1.1 Hz, 1H), 8.36 (d, J= 8.9 Hz, 1H), 8.16 (t, J= 1.5 Hz, 1H), 7.92 (d, J= 8.7 Hz, 1H), 7.84 (dd, J 8.8, 2.1 Hz, 1H), 7.08 (dd, J= 8.9, 2.5 Hz, 1H), 6.96 (d, J 2.4 Hz, 1H), 4.18 (dd, J= 11.8, 3.3 Hz, 1H), 4.10 - 3.88 (m, 7H), 3.53 - 3.48 (m, 2H), 3.30 - 3.21 (m, 3H), 3.10 (dd, J = 17.5, 3.3 Hz, 1H), 2.60 (s, 3H), 1.56 - 1.49 (m, 2H), 1.36 - 1.20 (m, 16H), 0.91 - 0.81 (m, 12H).

[0186] Absorption maximum (in acetone): 455 - 462 nm.

[0187] Example 12: Preparation of 5,6-dihydro-3,10-dimethoxybenzo[c]xanthylium dodecylbenzenesulfonate and preparation of the holographic medium containing 5,6-dihydro-3,10-dimethoxybenzo[c]xanthylium dodecylbenzenesulfonate:

[0188] Following general preparation procedure A, 4-methoxysalicylaldehyde was reacted with 6-methoxy-l-tetralone, and sodium dodecylbenzenesulfonate was used for ion exchange. A reddish-brown, highly viscous oil (0.41 g, 33% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared following preparation procedure D.

[0189] 1H NMR (600 MHz, CDCl3): δ 9.62 (s, 1H), 8.48 (d, J= 8.9 Hz, 1H), 8.38 (d, J= 9.0 Hz, 1H), 7.86 (d, J= 7.7 Hz, 2H), 7.65 - 7.62 (m, 1H), 7.34 (dd, J= 9.0, 2.4 Hz, 1H), 7.08 (s, 3H), 6.90 (d, J= 2.5 Hz, 1H), 4.10 (s, 3H), 3.98 (s, 3H), 3.42 (t, J= 7.6 Hz, 2H), 3.16 (t, J= 7.6 Hz, 2H), 1.52 - 1.44 (m, 1H), 1.32 - 1.01 (m, 18H), 0.88 - 0.79 (m, 6H).

[0190] Absorption maximum (in acetone): 472 - 481 nm.

[0191] Example 13: Preparation of 5,6-dihydro-3,10-dimethoxybenzo[c]xanthylium tetraphenylborate and preparation of the holographic medium containing 5,6-dihydro-3,10-dimethoxybenzo[c]xanthylium tetraphenylborate:

[0192] Following general preparation procedure A, 4-methoxysalicylaldehyde was reacted with 6-methoxy-l-tetralone, and sodium tetraphenylborate was used for ion exchange. An orange solid (0.41 g, 33% of theory over two steps) was obtained. A holographic medium containing this benzopyrylium dye was prepared following preparation procedure D.

[0193] 1 H NMR (600 MHz, CDCl3): δ 8.10 (d, J = 8.9 Hz, 1H), 7.50 - 7.43 (m , 9H), 7.19 (dd, J = 8.9, 2.4 Hz, 1H), 7.16 (d, J = 2.4 Hz, 1H), 6.99 - 6.92 (m, 10H), 6.85 (d, J= 2.5 Hz, 1H), 6.78 - 6.74 (m, 4H), 3.98 (s, 3H), 3.98 (s, 3H), 2.91 (t, J= 7.6 Hz, 2H), 2.70 (t, J= 7.6 Hz, 2H).

[0194] Absorption maximum (in acetone): 471 - 482 nm.

[0195] Non-inventive Example 1 (NEB-1): Preparation of the holographic medium containing 5,6-dihydro-3,10-dimethoxy-7-phenylbenzo[c]xanthylium perchlorate:

[0196] According to preparation procedure D, a holographic medium containing the dye 1 described above was prepared.

[0197] Non-inventive example 2 (NEB-2): Preparation of a holographic medium containing l,3,3-trimethyl-2-[2-(1-methyl-2-phenyl-lH-indol-3-yl)ethenyl]-3H-indolium bis(2-ethylhexyl)sulfobsuccinic acid ester):

[0198] According to preparation procedure D, a holographic medium containing the dye 2 described above was prepared.

[0199] Non-inventive example 3 (NEB-3): Preparation of a holographic medium containing 2-[2-[4-[(2-chloroethyl)methylamino]phenyl]ethenyl]-1,3,3-trimethyl-3 / / -indolium bis(2-ethylhexyl)sulfobsuccinic acid ester: According to preparation procedure D, a holographic medium containing the dye 3 described above was prepared.

[0200] Evaluation of the dyes according to the invention and not according to the invention:

[0201] The requirement for the photopolymer films produced here is, on the one hand, the highest possible transmission across the entire visible spectral range from 400 nm to 800 nm. The higher the transmission, the better the bleachability. On the other hand, the photopolymer films produced here must also be optically and chemically homogeneous, meaning they must be free of clouding or similar defects. If no clouding or optical inhomogeneities can be detected in the photopolymer film by optical inspection, then these are potentially suitable dyes for holographic media.

[0202] To evaluate and compare the bleachability of the photopolymer composition, the holographic media were tested in an identical manner: For each example, a sample was bleached for 180 s under light irradiation from a metal halide lamp, and in the next step, a transmission spectrum was recorded from 400 nm to 800 nm. The bleachability of the photopolymer films containing different benzopyrylium dyes was calculated using the following formula (1) with the experimentally recorded transmission spectrum data:

[0203] The following bleachability values ​​and visual assessments of the inventive and non-inventive examples were determined:

[0204] The results obtained show that the required properties of bleachability and optical clarity / homogeneity of a photopolymer are achieved with the benzopyrylium dyes according to the invention. The bleachability values ​​of the new and inventive benzopyrylium dyes (Examples 1 to 14) are all lower than those of the two cyanine / hemicyanine dyes of the non-inventive examples NEB-2 and NEB-3. Furthermore, no turbidity or optical inhomogeneities were observed in any of the inventive examples, except in Example NEB-1, which contains a benzopyrylium cation but is combined with a perchlorate anion and is therefore not according to the invention.

[0205] The non-inventive examples NEB1, NEB2 and NEB3 fail in at least one required property and are therefore unsuitable for providing the required properties.

[0206] In addition, the holographic performance Δn was tested on some films using the above-described measurement of the photopolymer films using two-beam interference in a reflection setup. The measurement results are summarized in Table 2 below.

[0207] T able 2. Results of the holographic power measurement using two-beam interference in a reflection arrangement according to the experimental setup described above and calculation for some examples.

[0208] The results of the Δnmax determination in Table 2 clearly show that the new benzopyrylium dyes can be used very well in combination with trialkylaryl borate salts in two-component photoinitiator systems, in photopolymers, and holographic media. The holographic performance is at least as good as that achieved with known cyanine dyes, as a comparison of Δn max-Determination of examples 2, 5, 7 and 10 with NEB-2.

Claims

Patent claims 1. A benzopyrylium dye of formula (I) (I) wherein R 200 , R 201 , R 202 , R 203 , R 204 , R 205 , R 206 , R 207 and R 208 independently of one another each represent hydrogen, alkyl, cycloalkyl, aralkyl, aryl, (het)aryl, hydroxy, alkoxy or dialkylamino, A represents a -CH2- or a -CH2-CH2 bridge, and the anion An n- has a molecular weight of ≥ 200 g / mol and does not contain a halogen atom and n is 1 to 3.

2. The benzopyrylium dye according to claim 1, wherein R 200 , R 205 , R 207 and R 208 represents hydrogen, A represents a -CH2-CH2 bridge, and R 204 represents a radical selected from the group consisting of hydrogen, C1- to C4-alkyl, or an arbitrarily substituted (het)aryl radical.

3. The benzopyrylium dye according to claim 1 or 2, wherein R 200 , R 205 , R 207 and R 208 are hydrogen atoms, A stands for a -CH2-CH2-bridge, R 201 is selected from the group consisting of hydrogen, C1- to C4-alkyl, hydroxy, C1- to C4-alkoxy, or dialkylamino, wherein the dialkylamino is selected from the group consisting of diethylamino, dimethylamino, diisopropylamino, a six-membered saturated ring attached via the N of the amino group, which may additionally contain an N or O and may be substituted by any non-ionic radicals, or a combination of at least two thereof, R 202 represents hydrogen, C1- to C4-alkyl, hydroxy or C1- to C4-alkoxy, R 203 either stands for hydrogen or with R 202 together form a -CH=CH-CH=CH-bridge, R 204represents hydrogen, C1- to C4-alkyl or an arbitrarily substituted (het)aryl radical, and R 206 ftj r hydrogen, hydroxy or C1- to C4-alkoxy. The benzopyrylium dye according to any one of the preceding claims, characterized in that the anion An n- is selected from the group consisting of C8 to C 25 - Alkanesulfonates, preferably C 13 - to C 25 -alkanesulfonates, C9- to C 25 -alkanoates, C9- to C 25 -alkenoates, C8- to C 25 -alkyl sulfates, preferably C 13 - to C 25 -alkyl sulfates, C8 to C 25 - Alkenyl sulfates, preferably C 13 - to C 25 -Alkenyl sulfates, polyether sulfates based on at least 5 equivalents of ethylene oxide or 5 equivalents of propylene oxide, bis-C4 to C 25 - Alkyl, C8 to C7 cycloalkyl, C3 to C8 alkenyl or C7 to C 11 -Aralkylsulfosuccinates, C8- to C 25-alkylsulfoacetates, by at least one radical of the group C4- to C 25 -alkyl and / or C1- to C 12 -Alkoxycarbonyl substituted benzenesulfonates, optionally substituted by nitro, cyano, hydroxy, C1- to C 25 -Alkyl, C1- to C 12 -Alkoxy, Amino, C1- to C 12 -Alkoxycarbonyl substituted naphthalene or biphenylsulfonates, optionally substituted by nitro, cyano, hydroxy, C1- to C 25 -Alkyl, C1- to C 12 -Alkoxy, C1- to C 12 -Alkoxycarbonyl substituted benzene, naphthalene or biphenyl disulfonates, by dinitro, C6,- to C 25 -Alkyl, C4- to C12-alkoxycarbonyl, benzoyl or toluoyl substituted benzoates or a mixture of at least two thereof. The benzopyrylium dye of the preceding claims, characterized in that the anion An n- ' is selected from the group consisting of C8 to C 25 -alkanesulfonates, preferably C 13 - to C 25-alkanesulfonates, C8 to C 25 -alkyl sulfates, preferably C 13 - to C 25 -alkyl sulfates, bis-C4 to C 25 -alkyl-, C5- to C7-cycloalkyl-, C3- to C8-alkenyl- or C7- to C 11 -Aralkylsulfosuccinates, C8- to C 25 -alkylsulfoacetates, by at least one radical of the group C4- to C 25 -alkyl and / or C1- to C 12 -Alkoxycarbonyl substituted benzenesulfonates and tetraphenylborates or a combination of at least two thereof. A process for the preparation of a benzopyrylium dye, in particular a benzopyrylium dye according to one of the preceding claims, comprising a multi-stage reaction sequence in which A. In a first reaction stage PI, at least the following steps are carried out: P1.i. Dissolving an appropriately selected 2-hydroxyarylcarbonyl derivative together with a corresponding indanone or tetralone derivative in a weak acid, P1.ii. Heating the mixture from P1.i. with the addition of a strong acid, P1.iii. Cooling and washing the mixture from P1.ii. with a non-polar, aprotic solvent, P1.iv. Separating the phase insoluble in the non-polar, aprotic solvent and dissolving this phase in water, B. in a second reaction stage P2. at least the following steps must be carried out: P2.i. Addition of an alkali salt of the dye anion An n- ' and a non-polar, aprotic solvent to the aqueous solution from P1.iv., P2.ii. Stir and, if necessary, heat the mixture from P2.i. and separate the aqueous phase and discard it, including the salts it contains. P2.iii. Washing the mixture from P2.ii. with water, preferably to the end point, and, P2.iv. Removal of the solvent, if necessary in vacuo, and drying of the Benzopyrylium dye, optionally in vacuum. Use of a benzopyrylium dye according to any one of claims 1 to 5 or prepared according to claim 6 in photocurable formulations in combination with an electron donor to improve the bleachability of photocurable materials. A photopolymer composition comprising a) matrix polymers, b) writing monomers, c) a non-photopolymerizable component, d) a photoinitiator system, at least comprising a suitable co-initiator and a benzopyrylium dye according to any one of claims 1 to 5 or prepared according to claim 6. A layer structure comprising at least the layers: A. a substrate layer A., ​​which may be part of a further layer structure, B. a photopolymer layer B., comprising a photopolymer composition according to claim 8, and C. optionally a top layer C., which may be part of a further layer structure. A layer structure comprising at least the following layers: A. a substrate layer A., ​​which may be part of a further layer structure, B. an exposed photopolymer layer B', which was prepared from the photopolymer composition according to claim 8 by exposure to light and C. optionally a cover layer C., which optionally is part of the further layer structure. A holographic medium containing a benzopyrylium dye according to any one of claims 1 to 5 or prepared according to claim 6 or a photopolymer composition according to any one of claims 8 to 10 or obtainable using a photopolymer composition according to any one of claims 8 to 10. A hologram obtainable from a holographic medium according to any one of claims 10 or 11. The hologram according to claim 12, characterized in that the hologram is selected from the group consisting of a reflection, transmission, in-line, off-axis, full-aperture transfer, white light transmission, Denisyuk, off-axis reflection, or edge-lit hologram, as well as a holographic stereogram, preferably a reflection, transmission, or edge-lit hologram, or a combination of at least two thereof. An optical display comprising a holographic medium according to claim 11 or a hologram according to claim 12 or 13. A use of the photopolymer composition according to claim 8 for producing a holographic medium or a hologram.A use of a holographic medium according to claim 11 or 12 for producing chip cards, identity documents, 3D images, product protection labels, labels, banknotes or holographic optical elements, in particular for optical displays or in media for implementing methods selected from the group consisting of eye tracking, sensor technology, LIDAR, augmented reality, head-mounted display, head-up display and virtual reality applications, in particular in the near infrared range and a combination of at least two thereof.

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