Thermostable photopolymers in the visible spectral range and photopolymer compositions containing same

Abstract

The invention relates to a photopolymer composition comprising a) matrix polymers, b) writing monomers, c) at least one photoinitiator system, d) optionally at least one non-photopolymerisable component, e) optionally catalysts, radical stabilisers, solvents, additives and other auxiliary and / or additional materials, wherein the at least one photoinitiator system c) consists of at least one colouring agent and at least one coinitiator, wherein at least one of the colouring agents has a structure according to formula (I) and the at least one coinitiator has a calculated oxidation potential (formula II), determined according to the below formula (1) via the quantum mechanical calculation of Gibbs energies at 298 K in the basic state and the oxidised state of the coinitiator, in particular the triaryl (alkyl) borate after geometry optimisation, involving conformer energy minimisation using the AMI force field, followed by an ab-initio conformer energy calculation based on the previously determined molecular geometry coordinates, in the solvent, acetonitrile, with a solvent field correction according to the PCM method, is in the range of 1.16 V to 1.37 V relative to the saturated calomel electrode (SCE) in acetonitrile (formula III).

Description

[0001] Thermostable photopolymers in the visible spectral range and photopolymer compositions therewith

[0002] The invention relates to photopolymer compositions using selected coinitiators, in particular triarylalkylborate salts as coinitiators with a selected oxidation potential, as well as to holographic media and holograms produced therefrom. Furthermore, the invention relates to a process for producing the specific coinitiators and the coinitiators obtainable by this process, as well as to a process for producing a holographic medium using the specific photopolymer composition including the specific coinitiators and to a holographic medium obtainable using the photopolymer composition according to the invention. Furthermore, the invention relates to a layer structure comprising a holographic medium according to the invention and also specific triarylalkylborate salts suitable as coinitiators.Furthermore, a method for calculating the oxidation potential against the saturated calomel electrode in acetonitrile of the special coinitiators is presented.

[0003] Photopolymer compositions that contain general forms of triarylalkylborate salts 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 photoinitiators containing a coinitiator and a dye. When using photopolymers, the refractive index modulation An 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 (DE).

[0004] In the simplest case of a hologram, which results from the superposition of two plane waves, the DE is the quotient of the intensity of the light diffracted during reconstruction and the sum of the intensities of the 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 at a given brightness.

[0005] To achieve the highest possible An and DE in holograms, the matrix polymers and the writing monomers of a photopolymer composition should generally be selected so that their refractive indices differ as much as possible. One possible way to achieve this is to use matrix polymers with the lowest possible refractive index and writing monomers with the highest possible refractive index. Suitable matrix polymers with a low refractive index include polyurethanes, which are obtained by reacting a polyol with a polyisocyanate component.

[0006] In addition to high DE and Δn values, it is also crucial for holographic media made from photopolymer compositions that the matrix polymers in the finished medium are highly cross-linked. If the degree of cross-linking is too low, the medium lacks sufficient stability. This can lead to the quality of holograms inscribed in the media being significantly reduced and changing over time, which is undesirable. In the worst case, the holograms can even be subsequently destroyed.

[0007] Furthermore, especially for the large-scale use of holographic media made from photopolymer compositions, it is of great importance that the photopolymer films containing the photopolymer composition have a wide processing window and can be exposed without loss of index modulation. The choice of a suitable photoinitiator is particularly crucial for the properties of the photopolymer.

[0008] Well-suited photoinitiators for photopolymer films of the type mentioned above can consist of type II photoinitiators. In these type II photoinitiators, triarylalkylborate salts can be combined as coinitiators with suitable sensitizers, such as cationic, anionic, or neutral dyes, as a photoinitiation system (PIS), so that a radical photopolymerization of suitable monomers can be triggered by UV, visible, or near-infrared light. The preparation of such PIS is widely described in the prior art, and selected tetraalkylammonium triarylalkylborates as coinitiators and dyes are commercially available. Furthermore, such PIS have already been used in photopolymers and holographic media, and their advantages have been described. For example, EP 2638544 describes cationic dyes, such as the dye of formula (I). which, together with the tris-(3-chloro-4-methylphenyl)hexylborate anion, can be used as a PIS for photocurable materials. Furthermore, EP 3058423 describes a wide selection of triarylalkylborate salts suitable for photopolymers in combination with dyes of the formula (I). The selection ranges from anions with electron-rich aromatics, such as the tris-(4-tert-butylphenyl)hexylborate anion, to anions with very electron-poor aromatics, such as the tris-(4-trifluoromethylphenyl)hexylborate anion. However, for all these PIS, such as those described in EP 3058423, dye-coinitiator combinations and photopolymer compositions comprising a dye and triarylalkylborate salts, no attention was paid to the thermal stability of the formulation in the unexposed state. In fact, many of the photopolymer compositions disclosed in EP 3058423 do not have sufficient thermal stability in the unexposed state.This means that under certain thermal stresses, such as 30 minutes of storage at 140 °C, which may be necessary to create holographic optical products, an undesirable side reaction occurs in the photopolymer film, which significantly reduces or even completely prevents the conversion of the photoreaction that begins upon exposure, thus significantly impairing the quality of the holograms to be recorded or making the formation of holograms impossible. Consequently, existing photopolymer films cannot be thermally treated to the necessary extent before exposure. However, this is disadvantageous for certain applications that require handling of the unexposed photopolymer film at elevated temperatures.

[0009] Therefore, it was an object of the invention to provide photopolymer compositions that enable the handling of unexposed photopolymer films under increased thermal stress. A further object was to provide photopolymer compositions that increase the thermal stability of photopolymer films in the unexposed state. Preferably, other properties such as bleachability or sensitivity should not be adversely affected during the exposure process. This technical problem was solved by the subject matter of claim 1 and its dependent claims.

[0010] A first subject of the invention is a photopolymer composition comprising: a) matrix polymers, b) writing monomers, c) at least one photoinitiator system, d) optionally at least one non-photopolymerizable component, e) optionally catalysts, radical stabilizers, solvents, additives and other auxiliaries and / or additives, wherein the at least one photoinitiator system c) consists of at least one dye and at least one coinitiator, wherein at least one of the dyes has a structure according to formula (I), wherein

[0011] R 201 is optional; if present for hydrogen, C1 to C 16 -Alkyl, C3 to C6 alkenyl, C5 to C7 cycloalkyl or C7 to C 16 -aralkyl or C6- to C 10 -Aryl stands,

[0012] R 203 for C1 to C 16 -Alkyl, C3 to C6 alkenyl, C5 to C7 cycloalkyl or C7 to C 16 -aralkyl or C6- to C 10-Aryl stands,

[0013] R 202 for hydrogen, C1 to C 16 -Alkyl, C3 to C6 alkenyl, C5 to C7 cycloalkyl or C7 to C 16 -Aralkyl, C6- to C 10 -aryl or hetaryl,

[0014] R 204 represents hydrogen, C1- to C4-alkyl, C1- to C4-alkoxy, halogen, cyano, nitro or C1- to C4-alkoxycarbonyl,

[0015] A together with X 1 and X 2 and the one between X 1 and X 2 bonded C atom represents a five- or six-membered aromatic or quasi-aromatic or partially hydrogenated heterocyclic ring which may contain 1 to 4 heteroatoms and / or be benz- or naphthanellated and / or substituted by non-ionic radicals,

[0016] X 2 represents N, O or S, preferably N, and

[0017] X 1 for O, S, CR 205 R 206 or -CH=CH-, preferably for CR 205 R 206 where R205 and R 206 independently of one another represent C1- to C4-alkyl, C3- to C6-alkenyl, C4- to C7-

[0018] Cycloalkyl, C7- to C 10 -aralkyl or C6-aryl and

[0019] An- represents an anion selected from the group consisting of halide, cyanide, nitrate, azide, perchlorate, hexafluorophosphate, hexafluoroantimonate, any substituted phosphate, any substituted phosphonate, any substituted sulfonimide, such as, for example, bis(trifluoromethyl)sulfonimide, any substituted organic borate, such as, for example, tetrafluoroborate, tetraarylborate, triarylalkylborate or cyanotriarylborate, any substituted alkyl or alkenyl sulfate, any substituted mono- or di-sulfonate, such as, for example, methylsulfonate, p-toluenesulfonate, trifluoromethylsulfonate, or sulfusuccinate, or any substituted organic mono- or di-carboxylate, and the at least one coinitiator has a calculated oxidation potential, determined according to the formula (1) below, by the quantum mechanical calculation of the Gibbs energies at 298 K of the ground state and the oxidized state of the coinitiator, in particular the triarylalkyl borate after geometry optimization, consisting of conformer energy minimization using the AMI force field followed by ab initio conformer energy calculation starting from the previously determined molecular geometry coordinates, in the solvent acetonitrile with solvent field correction according to the PCM method, in the range of 1.16 V to 1.37 V against the saturated calomel electrode (SCE) in acetonitrile (1)

[0020] The matrix polymer a) can be any matrix polymer a) which the person skilled in the art knows for the inventive

[0021] photopolymer composition. Suitable matrix polymers a) for the

[0022] Photopolymer compositions can in particular be crosslinked and particularly preferably three-dimensionally crosslinked.

[0023] It is preferred that the matrix polymers a) are polyurethanes, wherein the polyurethanes can be obtained in particular by reacting at least one polyisocyanate component a1) with at least one isocyanate-reactive component a1).

[0024] The polyisocyanate component a1) preferably comprises at least one organic compound having at least two NCO groups. These organic compounds can be, in particular, monomeric di- and triisocyanates, polyisocyanates, and / or NCO-functional prepolymers. The polyisocyanate component a1) can also contain or consist of mixtures of monomeric di- and triisocyanates, polyisocyanates, and / or NCO-functional prepolymers.

[0025] Monomeric di- and triisocyanates can be any compounds or mixtures thereof that are well known to those skilled in the art. These compounds can have aromatic, araliphatic, aliphatic, or cycloaliphatic structures. In minor amounts, the monomeric di- and triisocyanates can also comprise monoisocyanates, i.e., organic compounds containing an NCO group.

[0026] Examples of suitable monomeric di- and triisocyanates are 1,4-butane diisocyanate, 1,5-pentane diisocyanate, 1,6-hexane diisocyanate (hexamethylene diisocyanate, HDI), 2,2,4-trimethylhexamethylene diisocyanate and / or 2,4,4-trimethylhexamethylene diisocyanate (TMDI), isophorone diisocyanate (IPDI), 1,8-diisocyanato-4-(isocyanatomethyl)-octane, bis-(4,4'-isocyanatocyclohexyl)methane and / or bis-(2',4-isocyanatocyclohexyl)methane and / or mixtures thereof with any isomer content, 1,4-cyclohexane diisocyanate, the isomeric bis-(isocyanatomethyl)cyclohexanes, 2,4- and / or 2,6-diisocyanato-1-methylcyclohexane (hexahydro-2,4- and / or 2,6-toluene diisocyanate, H6-TDI), 1,4-phenylene diisocyanate, 2,4- and / or 2,6-toluene diisocyanate (TDI), 1,5-naphthylene diisocyanate (NDI), 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1,3-bis(isocyanatomethyl)benzene (XDI) and / or the analogous 1,4-isomer or any mixtures of the aforementioned compounds.

[0027] Suitable polyisocyanates are compounds with urethane, urea, carbodiimide, acylurea, amide, isocyanurate, allophanate, biuret, oxadiazinetrione, uretdione and / or iminooxadiazinedione structures, which are obtainable from the aforementioned di- or triisocyanates.

[0028] The polyisocyanates are particularly preferably oligomerized aliphatic and / or cycloaliphatic di- or triisocyanates, with the above-mentioned aliphatic and / or cycloaliphatic di- or triisocyanates being particularly suitable. Polyisocyanates with isocyanurate, uretdione, and / or iminooxadiazinedione structures, as well as biurets based on HDI or mixtures thereof, are very particularly preferred.

[0029] Suitable prepolymers contain urethane and / or urea groups, as well as optionally other structures resulting from the modification of NCO groups, as mentioned above. Such prepolymers are obtainable, for example, by reacting the above-mentioned monomeric di- and triisocyanates and / or polyisocyanates (all) with isocyanate-reactive compounds (b1).

[0030] Alcohols, amino or mercapto compounds, preferably alcohols, can be used as isocyanate-reactive compounds alll). These can be, in particular, polyols. Polyester, polyether, polycarbonate, poly(meth)acrylate, and / or polyurethane polyols can be used very particularly preferably as isocyanate-reactive compounds alll).

[0031] Suitable polyester polyols include, for example, linear polyester polyols or branched polyester polyols, which can be obtained in a known manner by reacting aliphatic, cycloaliphatic or aromatic di- or polycarboxylic acids or their anhydrides with polyhydric alcohols having an OH functionality of ≥ 2. Examples of suitable di- or polycarboxylic acids are polybasic carboxylic acids such as succinic, adipic, suberic, sebacic, decanedicarboxylic, phthalic, terephthalic, isophthalic, tetrahydrophthalic or trimellitic acid, and acid anhydrides such as phthalic, trimellitic or succinic anhydride, or any mixtures thereof. The polyester polyols can also be based on natural raw materials such as castor oil. It is also possible for the polyester polyols to be based on homopolymers or copolymers of lactones, which are preferably obtained by addition of lactones orLactone mixtures such as butyrolactone, ε-caprolactone and / or methyl-ε-caprolactone to hydroxy-functional compounds such as polyhydric alcohols with an OH functionality ≥ 2, for example of the type mentioned below.

[0032] Examples of suitable alcohols are all polyhydric alcohols such as the C2- C 12 -diols, the isomeric cyclohexanediols, glycerol or any mixtures thereof.

[0033] Suitable polycarbonate polyols are accessible in a conventional manner by reacting organic carbonates or phosgene with diols or diol mixtures.

[0034] Suitable organic carbonates are dimethyl, diethyl and diphenyl carbonate.

[0035] Suitable diols or mixtures include the polyhydric alcohols with an OH functionality ≥ 2 mentioned in the context of the polyester segments, preferably 1,4-butanediol, 1,6-hexanediol, and / or 3-methylpentanediol. Polyester polyols can also be converted into polycarbonate polyols.

[0036] Suitable polyether polyols are optionally block-structured polyaddition products of cyclic ethers to OH- or NH-functional starter molecules.

[0037] Suitable cyclic ethers include styrene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin, and any mixtures thereof. Polyhydric alcohols with an OH functionality of ≥ 2, as well as primary or secondary amines and amino alcohols, can be used as starters.

[0038] Preferred polyether polyols are those of the aforementioned type based exclusively on propylene oxide or random or block copolymers based on propylene oxide with other 1-alkylene oxides. Particular preference is given to propylene oxide homopolymers and random or block copolymers containing oxyethylene, oxypropylene, and / or oxybutylene units, where the proportion of oxypropylene units, based on the total amount of all oxyethylene, oxypropylene, and oxybutylene units, is at least 20% by weight, preferably at least 45% by weight. Oxypropylene and oxybutylene encompass all respective linear and branched C3 and C4 isomers.

[0039] In addition, low molecular weight, ie with molecular weights ≤ 500 g / mol, short-chain, ie containing 2 to 20 carbon atoms, aliphatic, araliphatic or cycloaliphatic di-, tri- or polyfunctional alcohols are also suitable as components of the polyol component alll) as polyfunctional, isocyanate-reactive compounds.

[0040] In addition to the above-mentioned compounds, these can be, for example, neopentyl glycol, 2-ethyl-2-butylpropanediol, trimethylpentanediol, positionally isomeric diethyloctanediols, cyclohexanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, 1,2- and 1,4-cyclohexanediol, hydrogenated bisphenol A, 2,2-bis(4-hydroxycyclohexyl)propane or 2,2-dimethyl-3-hydroxypropionic acid, 2,2-dimethyl-3-hydroxypropyl ester. Examples of suitable triols are trimethylolethane, trimethylolpropane, or glycerol. Suitable higher-functionality alcohols are di(trimethylolpropane), pentaerythritol, dipentaerythritol, or sorbitol.

[0041] It is particularly preferred if the polyol component is a difunctional polyether, polyester or a polyether-polyester-block-copolyester or a polyether-polyester block copolymer with primary OH functions.

[0042] It is also possible to use amines as isocyanate-reactive compounds. Examples of suitable amines are ethylenediamine, propylenediamine, diaminocyclohexane, 4,4'-dicylohexylmethanediamine, isophoronediamine (IPDA), difunctional polyamines such as Jeffamine®, and amine-terminated polymers, particularly with number-average molecular weights ≤ 10,000 g / mol. Mixtures of the aforementioned amines can also be used.

[0043] It is also possible to use all amino alcohols as isocyanate-reactive compounds. Examples of suitable amino alcohols are the isomeric aminoethanols, the isomeric aminopropanols, the isomeric aminobutanols, and the isomeric aminohexanoyls, or any mixtures thereof.

[0044] All of the above-mentioned isocyanate-reactive compounds (alll) can be mixed with each other as desired.

[0045] It is also preferred if the isocyanate-reactive compounds alll) have a number-average molar mass of ≥ 200 and ≤ 10,000 g / mol, more preferably ≥ 500 and ≤ 8,000 g / mol, and most preferably ≥ 800 and ≤ 5,000 g / mol. The OH functionality of the polyols is preferably 1.5 to 6.0, particularly preferably 1.8 to 4.0.

[0046] The prepolymers of the polyisocyanate component a1) can in particular have a residual content of free monomeric di- and triisocyanates of < 1 wt.%, particularly preferably < 0.5 wt.% and very particularly preferably < 0.3 wt.%.

[0047] It is also possible for the polyisocyanate component a1) to contain, in whole or in part, organic compounds whose NCO groups are fully or partially reacted with blocking agents known from coating technology. Examples of blocking agents are alcohols, lactams, oximes, malonic esters, pyrazoles, and amines, such as butanone oxime, diisopropylamine, diethyl malonate, acetoacetic ester, 3,5-dimethylpyrazole, ε-caprolactam, or mixtures thereof.

[0048] It is particularly preferred if the polyisocyanate component a1) comprises compounds with aliphatically bonded NCO groups, where aliphatically bonded NCO groups are understood to be groups bonded to a primary carbon atom. The isocyanate-reactive component a11) preferably comprises at least one organic compound having an average of at least 1.5 and preferably 2 to 3 isocyanate-reactive groups. For the purposes of the present invention, hydroxyl, amino, or mercapto groups are preferred as isocyanate-reactive groups.

[0049] The isocyanate-reactive component may in particular comprise compounds which have on average at least 1.5 and preferably 2 to 3 isocyanate-reactive groups.

[0050] Suitable polyfunctional, isocyanate-reactive compounds of component all) are, for example, the compounds alll) described above.

[0051] In a further preferred embodiment, it is provided that the substance catalyzing the polyurethane formation originates from the group of tin-based organyls, or is a complex based on iron(II), iron(III), gallium(III), bismuth(III), vanadium(III), vanadium(IV), terbium(III), tin(II), zinc(II), zirconium(IV) with suitable mono- or bidentate ligands.

[0052] The writing monomer b) can be any writing monomer that a person skilled in the art would select for the photopolymer composition according to the invention. 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.

[0053] Suitable acrylate writing monomers are in particular compounds of the general formula (III) where m ≥ 1 and m ≤ 4 and R 5 a linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted with heteroatoms organic radical and / or R 6 hydrogen, a linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted by heteroatoms organic radical. R6 is particularly preferred 8 Hydrogen or methyl and / or R 5 a linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted by heteroatoms organic radical.

[0054] In this context, acrylates and methacrylates are referred to as esters of acrylic acid and methacrylic acid, respectively. Examples of preferred acrylates and methacrylates are phenyl acrylate, phenyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, phenoxyethoxyethyl acrylate, phenoxyethoxyethyl methacrylate, phenylthioethyl acrylate, phenylthioethyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, 1,4-bis-(2-thionaphthyl)-2-butyl acrylate, 1,4-bis-(2-thionaphthyl)-2-butyl methacrylate, bisphenol A diacrylate, bisphenol A dimethacrylate, and their ethoxylated analogues or N-carbazolyl acrylates.

[0055] Urethane acrylates are understood here to be compounds with at least one acrylic acid ester group and at least one urethane bond. Such compounds can be obtained, for example, by reacting a hydroxy-functional acrylate or methacrylate with an isocyanate-functional compound.

[0056] Examples of usable isocyanate-functional compounds are monoisocyanates and the monomeric diisocyanates, triisocyanates, and / or polyisocyanates mentioned under a1). Examples of suitable monoisocyanates are phenyl isocyanate, the isomeric methylthiophenyl isocyanates, di-, tri-, or polyisocyanates mentioned above, as well as triphenylmethane-4,4',4"-triisocyanate and tris(p-isocyanatophenyl)thiophosphate or their derivatives with urethane, urea, carbodiimide, acylurea, isocyanurate, allophanate, biuret, oxadiazinetrione, uretdione, iminooxadiazinedione structures, and mixtures thereof. Aromatic di-, tri-, or polyisocyanates are preferred.

[0057] Examples of hydroxy-functional acrylates or methacrylates used for the production of urethane acrylates include compounds such as 2-hydroxyethyl (meth)acrylate, polyethylene oxide mono(meth)acrylates, polypropylene oxide mono(meth)acrylates, polyalkylene oxide mono(meth)acrylates, poly(ε-caprolactone) mono(meth)acrylates, such as Tone® M100 (Dow, Schwalbach, DE), 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-hydroxy-2,2-dimethylpropyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl acrylate, the hydroxy-functional mono-, di- or tetraacrylates of polyhydric alcohols such as trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, ethoxylated, propoxylated or alkoxylated trimethylolpropane, glycerol, Pentaerythritol, dipentaerythritol, or technical mixtures thereof. 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and poly(ε-caprolactone) mono(meth)acrylate are preferred.

[0058] Also usable are the known hydroxyl-containing epoxy (meth)acrylates with OH contents of 20 to 300 mg KOH / g or hydroxyl-containing polyurethane (meth)acrylates with OH contents of 20 to 300 mg KOH / g or acrylated polyacrylates with OH contents of 20 to 300 mg KOH / g as well as mixtures thereof with one another and mixtures with hydroxyl-containing unsaturated polyesters as well as mixtures with polyester (meth)acrylates or mixtures of hydroxyl-containing unsaturated polyesters with polyester (meth)acrylates.

[0059] Particularly preferred are urethane acrylates obtainable from the reaction of tris(p-isocyanatophenyl)thiophosphate and / or m-methylthiophenyl isocyanate with alcohol-functional acrylates such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and / or hydroxybutyl (meth)acrylate or reaction products of 2-isocyanatoethyl acrylate and / or 2-isocyanatoethyl methacrylate and / or l,l-(bisacryloyloxymethyl)ethyl isocyanate with optionally substituted naphthols.

[0060] It is also possible for the writing monomer to comprise or consist of further unsaturated compounds such as α,β-unsaturated carboxylic acid derivatives such as maleates, fumarates, maleimides, acrylamides, furthermore vinyl ethers, propenyl ethers, allyl ethers and compounds containing dicyclopentadienyl units as well as olefinically unsaturated compounds such as styrene, α-methylstyrene, vinyltoluene and / or olefins.

[0061] The at least one photoinitiator system c) 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 c) 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.

[0062] 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.

[0063] 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. First, the dye absorbs a photon and transfers energy from an excited state to the coinitiator. The coinitiator releases the polymerization-initiating radicals through electron or proton transfer or direct hydrogen abstraction.

[0064] For the purposes of this invention, Type II photoinitiators are preferably used. Such photoinitiator systems are described in principle in EP 0 223 587 A and preferably consist of a mixture of one or more dyes.

[0065] Suitable dyes of component c1), which together with a compound of formula (II) form a type II photoinitiator, are the cationic dyes described in WO 2012062655 in combination with the anions just described therein.

[0066] Cationic dyes are preferably understood to mean those of the following classes: acridine dyes, xanthene dyes, thioxanthene dyes, phenazine dyes, phenoxazine dyes, phenothiazine dyes, tri(het)aryhnethane dyes - in particular diamino and triamino(het)aryhnethane dyes, mono-, di-, tri- and pentamethine cyanine dyes, hemicyanine dyes, externally cationic merocyanine dyes, externally cationic neutrocyanine dyes, nulhnethine dyes - in particular naphtholactam dyes, streptocyanine dyes. Such dyes are described, for example, in H. Bemeth in Ulhnann's Encyclopedia of Industrial Chemistry, Azine Dyes, Wiley-VCH Verlag, 2008, H. Bemeth in Ulhnann's Encyclopedia of Industrial Chemistry, Methine Dyes and Pigments, Wiley-VCH Verlag, 2008, T. Gessner, U. Mayer in Ulhnann's Encyclopedia of Industrial Chemistry, Triarylmethane and Diarylmethane Dyes, Wiley-VCH Verlag, 2000.

[0067] Particularly preferred are phenazine dyes, phenoxazine dyes, phenothiazine dyes, tri-(het)arylmethane dyes - in particular diamino and triamino(het)arylmethane dyes, mono-, di-, tri- and pentamethine cyanine dyes, hemicyanine dyes, nullmethine dyes - in particular naphtholactam dyes, streptocyanine dyes.

[0068] Examples of cationic dyes are Astrazon Orange G, Basic Blue 3, Basic Orange 22, Basic Red 13, Basic Violet 7, Methylene Blue, New Methylene Blue, Azure A, 2,4-Diphenyl-6-(4-methoxyphenyl)pyrylium, Safianin O, Astraphloxine, Brilliant Green, Crystal Violet, Ethyl Violet and Thionin.

[0069] Preferred anions (An-) of the cationic dyes are in particular C8 to C 25 -alkanesulfonate, preferably C 13 - to C 25 -alkanesulfonate, C3- to C 18 -Perfluoroalkanesulfonate, C4- to C 18- Perfluoroalkanesulfonate, which carries at least 3 hydrogen atoms in the alkyl chain, C9 to C 25 -alkanoate, C9- to C 25 -alkenoate, C8- to C 25 -alkyl sulfate, preferably C 13 - to C 25 -Alkyl sulfate, C8- to C 25 - Alkenyl sulfate, preferably C 13 - to C 25 -Alkenyl sulfate, C3- to C 18 -Perfluoroalkyl sulfate, C4- to C 18 - Perfluoroalkyl sulfate containing at least 3 hydrogen atoms in the alkyl chain, polyether sulfates based on at least 4 equivalents of ethylene oxide and / or 4 equivalents of propylene oxide, bis-C4 to C 25 -alkyl-, C5- to C7-cycloalkyl-, C3- to C8-alkenyl- or C7- to C 11 -Aralkyl sulfosuccinate, bis-C2- to C-substituted by at least 8 fluorine atoms 10 -alkyl sulfosuccinate, C8- to C 25 -Alkyl- sulfoacetates, by at least one residue of the group halogen, C4- to C 25 -alkyl, perfluoro-C1- to C8-alkyl and / or C1- to C12 -Alkoxycarbonyl substituted benzenesulfonate, optionally by nitro, cyano, hydroxy, C1- to C 25 -Alkyl, C1- to C 12 -Alkoxy, Amino, C1- to C 12 -Alkoxycarbonyl or chlorine-substituted naphthalene- or biphenylsulfonate, optionally substituted by nitro, cyano, hydroxy, C1- to C 25 -Alkyl, C1- to C 12 -Alkoxy, C1- to C 12 - Alkoxycarbonyl or chlorine substituted benzene, naphthalene or biphenyl disulfonate, by dinitro, C6- to C 25 -Alkyl, C4- to C 12 -Alkoxycarbonyl, benzoyl, chlorobenzoyl or toluoyl substituted benzoate, the anion of naphthalenedicarboxylic acid, diphenyl ether disulfonate, sulfonated or sulfated, optionally at least monounsaturated C8 to C 25 - Fatty acid esters of aliphatic C1 to C8 alcohols or glycerol, bis-(sulfo-C2 to C6 alkyl)-C3 to C 12 -alkanedicarboxylic acid esters, bis-(sulfo-C2- to C6-alkyl)-itaconic acid esters, (sulfo-C2- to C6-alkyl)- C6- to C18 -alkanecarboxylic acid esters, (sulfo-C2- to C6-alkyl)-acrylic or methacrylic acid esters, optionally substituted by up to 12 halogen radicals triscatechol phosphate, an anion of the group tetraphenylborate, cyanotriphenylborate, tetraphenoxyborate, C4- to C 12 -Alkyl triphenylborate, whose phenyl or phenoxy radicals may be substituted by halogen, C1- to C4-alkyl and / or C1- to C4-alkoxy, C4- to C 12 -Alkyl trinaphthyl borate, tetra-C1- to C 20 -alkoxyborate, 7,8- or 7,9-dicarba-nido-undecaborate(l-) or (2-), which may be substituted at the B and / or C atoms by one or two C1 to C 12 -alkyl or phenyl groups, dodecahydro-dicarbadodecaborate(2-) or B-C1- to C 12-Alkyl-C-phenyl-dodecahydro-dicarbadodecaborate(l-), where in the case of polyvalent anions such as naphthalenedisulfonate, An- stands for an equivalent of this anion, and where the alkane and alkyl groups can be branched and / or substituted by halogen, cyano, methoxy, ethoxy, methoxycarbonyl or ethoxycarbonyl.

[0070] For the purposes of this invention, the anions described in WO 2012062655 are preferably used.

[0071] It is also preferred if the anion An- of the dye has an AClogP in the range from 1 to 30, particularly preferably in the range from 1 to 12, and especially preferably in the range from 1 to 6.5. The AClogP is calculated according to J. Comput. Aid. Mol. Des. 2005, 19, 453; Virtual Computational Chemistry Laboratory, http: / / www.vcclab.org.

[0072] Suitable coinitiators of component c11) for a Type II photoinitiator system are borate salts, particularly triarylalkyl borate salts, which are described in WO 2015 / 055576. Other coinitiators can be pentacoordinated silicates or tertiary aromatic amines.

[0073] The at least one non-photopolymerizable component d) can be any component d) that a person skilled in the art would select for the photopolymer composition according to the invention. Preferably, the photopolymer composition additionally contains urethanes as additives to component d), wherein the urethanes may in particular be substituted by at least one fluorine atom.

[0074] Preferably, the urethanes can have the general formula (XVI) where o≥l and o≤8 and R 7 , R 8 and R 9linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted with heteroatoms organic radicals and / or R 8 , R 9 are independently hydrogen, wherein preferably at least one of the radicals R 7 , R 8 , R 9 is substituted with at least one fluorine atom and particularly preferably R 7 is an organic radical containing at least one fluorine atom. R is particularly preferably 9 a linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted with heteroatoms such as fluorine.

[0075] In a preferred embodiment of the photopolymer composition, the at least one

[0076] Dye according to the structure of formula (I) has the following radicals:

[0077] R 201is optional; when present, represents hydrogen, methyl, ethyl, propyl, butyl, benzyl or phenethyl,

[0078] R 203 represents methyl, ethyl, propyl, butyl, benzyl or phenethyl,

[0079] R 202 represents hydrogen, methyl or phenyl,

[0080] R 204 represents hydrogen, methyl, ethyl, cyclohexyl, phenyl, tolyl, anisyl or chlorophenyl,

[0081] A together with X 1 and X 2and the carbon atom bonded between them for pyridin-2-ylene or pyridin-4-ylene, quinolin-2-ylene or quinolin-4-ylene, l,3-thiazolin-2-ylene, l,3-thiazolin-2-ylene, benzothiazolin-2-ylene, l,3,4-thiadizol-2-ylene, l,3-oxazolin-2-ylene, Benzoxazol-2-ylene, imidazol-2-ylene, imidazolin-2-ylene, benzimidazol-2-ylene, pyrrolin-2-ylene, l,3,4-triazol-2-ylene, 3-H-indol-2-ylene or quinoxalin-2-ylene is represented by methyl, ethyl, benzyl, methoxy, chlorine, cyano, nitro or methoxycarbonyl are substituted, whereby in the case of In imidazol-2-ylene, imidazolin-2-ylene and benzimidazol-2-ylene both N atoms are substituted by R41b and in the case of l,3,4-thiadizole-2-ylene the substituents are selected from the group consisting of dimethylamino, diethylamino, dipropylamino, dibutylamino, N-methyl, N-cyanoethylamino, bis(cyanoethyl)amino, N-methyl-N-phenylamino, pyrrolidines, piperidino and morpholino, or

[0082] A together with X 1 and X 2and the C atom bonded therebetween represents 2H-pyran-2-ylene, 4H-pyran-4-ylene, 2H-thiopyran-2-ylene, 4H-thiopyran-4-ylene, which are substituted by two residues of the group phenyl, tolyl or anisyl

[0083] In a preferred embodiment of the photopolymer composition, the at least one dye has a structure of formula (XVII), where R 201 and R 203 independently of one another represent methyl, ethyl or benzyl, preferably

[0084] Methyl and

[0085] R 202 represents hydrogen, methyl or phenyl, preferably phenyl.

[0086] In a preferred embodiment of the photopolymer composition, the at least one dye according to formula (I) or formula (XVII) present has an organically substituted sulfonate as anion (An-).

[0087] In a preferred embodiment of the photopolymer composition, the at least one coinitiator is a triarylalkylborate salt.

[0088] In a preferred embodiment of the photopolymer composition, the coinitiator contains a triarylalkyl borate according to formula (II), wherein the triarylalkyl borates preferably have a calculated oxidation potential between 1.16 V vs. SCE and 1.37 V vs. SCE in acetonitrile and wherein

[0089] A represents a methylene group or any substituted methine group which may optionally be substituted with R 100 can form a ring with up to 10 members, preferably represents a methylene group,

[0090] R 100 represents hydrogen or a C1 to C1-alkyl radical optionally substituted by hydroxyl and / or alkoxy and / or acyloxy and / or halogen 20 -alkyl-, C3- to C 12 -alkyl radical, C3- to C 20 -Alkenyl-, C3- to C 20-Alkynyl-, C5- to C7-cycloalkyl- or C7- to C 13 -aralkyl radical,

[0091] R 101 , R 102 , and R 103 for up to five independently selected residues from C1 to C 10 -alkyl-, C3- to C5-alkenyl-, C3- to C5-alkynyl-, C5- to C7-cycloalkyl- or C7- to C 13 -Aralkyl radical, halogen, cyano, trifluoromethyl, trichloromethyl, difluoromethyl, dichloromethyl, trifluoromethylthioyl, trichloromethylthioyl, C1 to C4 alkoxy, trifluoromethoxy, trichloromethoxy, C1 to C4 alkylthioyl, thioyl, difluoromethoxy, difluoromethylthioyl, carboxyl, carbonyl, 2-, 3-, or 4-pyridyl, or any substituted aryl radicals or hydrogen,

[0092] K +represents an arbitrarily substituted organocation of valence n based on nitrogen, phosphorus, oxygen, sulfur, and / or iodine, and n represents 1, 2, or 3. Preferably, in this embodiment of the photopolymer composition, A represents a methylene group.

[0093] In a preferred embodiment of the photopolymer composition, the triarylalkyl borate of structure (II) R 100 for a C1 to C 20 -alkyl-, C3- to C 12 -Alkyl, C5- to C7- cycloalkyl- or C7- to C 13 -aralkyl radical and R 101 , R 102 and R 103 represents one or two independently selected radicals from C1- to C4-alkyl, halogen, cyano, trifluoromethyl, C1- to C4-alkoxy or any substituted aryl radicals or hydrogen. Preferably, at least one radical is selected from the radicals R 101 , R 102 and R 103no hydrogen. Preferably, at least one of the at least two radicals R 101 , two residues R 102 and two residues R 103 in the meta-position or para-position to the B atom, particularly preferably in the para-position. In the case of two radicals R 101 , R 102 and R 103 the two radicals are each in the meta-position and para-position to the B atom. In this embodiment of the photopolymer composition, A preferably represents a methylene group.

[0094] Furthermore, the triarylalkyl borate of the structure (II) R 100 represents a C3 to C5 alkyl radical, where A is preferably a methylene group and at least one of the radicals R 101 , R 102 , and R 103 represents one or two independently selected radicals from C1 to C4 alkyl radicals and halogen substituents in the meta and / or para position, preferably at least R 102 and / or R 103for independently selected halogen substituents, where halogen substituents include not only halogen radicals such as Cl radical or F radical but also trihaloalkyl radicals, in particular trihalomethyl radicals and trihaloethyl radicals, in particular trifluoromethyl radicals and trichloromethyl radicals.

[0095] In a further preferred embodiment of the photopolymer composition, the triarylalkyl borate of structure (II) R 100 for a C3 to C 12 -alkyl radical and R 101 , R 102 , and R 103 independently of one another represent one or two radicals in the meta or para position selected from the group consisting of C1 to C4 alkyl radicals and halogen substituents, preferably at least R 102 and / or R 103 represents a halogen substituent. In the case of two radicals R 101 , two R 102 , and two R 103the two residues are in the meta-position and para-position to the B atom. Preferably at least R 102 and / or R 103 a halogen substituent. In this embodiment, A is preferably a methylene group.

[0096] Furthermore, the triarylalkyl borate of the structure (II) R 100 represents C3 to C5 alkyl radical, where A is preferably a methylene group and R 101 , R 102 , and R 103 represents one or two independently selected radicals from C1 to C4 alkyl radicals and halogen substituents in the meta and / or para position, preferably at least R 102 and / or R 103 Halogen substituent.

[0097] Very particular preference is given to the triarylalkylborate salts shown below, where K + each is any organocation based on nitrogen, phosphorus, oxygen, sulfur or iodine:

[0098] In a preferred embodiment of the photopolymer composition, the organocation K + of the triarylalkylborate salt is a nitrogen- or phosphorus-based, mono- or divalent cation, preferably a nitrogen-based mono- or divalent cation, particularly preferably a monovalent ammonium cation.

[0099] In a preferred embodiment of the photopolymer composition, the at least one coinitiator has an oxidation potential in a range between 1.20 V vs. SCE and 1.36 V vs. SCE in acetonitile, preferably between 1.25 V vs. SCE and 1.35 V vs. SCE and particularly preferably between 1.28 V vs. SCE and 1.34 V vs. SCE.

[0100] Preferably, K +an organocation of valence n based on nitrogen, such as ammonium ions, pyridinium ions, pyridazinium ions, pyrimidinium ions, pyrazinium ions, imidazolium ions, pyrrolidinium ions, which may optionally carry further functional groups such as ethers, esters, amides and / or carbamates in one or more side chains and which may also be present in oligomeric, polymeric or bridging form.

[0101] Preferably, K + an organocation of valence n based on phosphorus, such as an arbitrarily substituted tetraalkylphosphonium, trialkylarylphosphonium, dialkyldiarylphosphonium, alkyltriarylphosphonium, or tetraarylphosphonium cation, which may optionally carry further functional groups such as carbonyls, amides and / or carbamates in one or more side chains and which may also be present in oligomeric, polymeric or bridging form.

[0102] Furthermore, K is preferred + an organocation of valence n based on oxygen, such as an arbitrarily substituted pyrylium cation, which can also be present in fused form as in the benzopyrylium, flavylium, naphthoxanthenium cation, or a polymeric cation with the substitution patterns mentioned.

[0103] Furthermore, K is preferred + to an organocation of valence n based on sulfur, such as an onium compound of sulfur, the same or different optionally substituted C4 to C 14 -alkyl-, C6- to C 10 -aryl-, C7- to C 12 -arylalkyl or C5 to C6 cycloalkyl radicals and / or oligomeric or polymeric repeating linking units to form sulfonium salts with 1 ≤ n ≤ 3, or such as thiopyrylium cations or polymeric cations with the substitution patterns mentioned.

[0104] Furthermore, K is preferred+ to an organocation of valence n based on iodine, such as an onium compound of iodine, the same or different optionally substituted C1 to C 22 -alkyl-, C6- to C 14 -aryl-, C7- to C 15 -arylalkyl or C5 to C7 cycloalkyl radicals and / or oligomeric or polymeric repeating linking units to form iodonium salts with 1 ≤ n ≤ 3, or like other polymeric cations with the mentioned substitution patterns.

[0105] The photoinitiator system c) may also contain another coinitiator (till) such as trichloromethyl initiators, iodonium salts, sulfonium salts, aryloxide initiators, bisimidazole initiators, ferrocene initiators, oxime initiators, thiol initiators or peroxide initiators.

[0106] It may be advantageous to use mixtures of these coinitiators and various dyes. Depending on the radiation source used, the type and concentration of the PIS must be adapted in a manner known to those skilled in the art. Further details are described, for example, in PKT Oldring (Ed.), Chemistry & Technology of UV & EB Formulations For Coatings, Inks & Paints, Vol. 3, 1991, SITA Technology, London, pp. 61-328. It is very particularly preferred if the PIS comprises a combination of dyes whose absorption spectra at least partially cover the spectral range from 400 to 1200 nm, with at least one coinitiator matched to the dyes. It is also preferred if at least one photoinitiator suitable for a laser light color is present in the photopolymer composition.It is also further preferred if the photopolymer composition contains a suitable photoinitiator for at least two laser light colors selected from the wavelength range of 400-1200 nm. Finally, it is very particularly preferred if the photopolymer composition contains a suitable photoinitiator for each of the laser light colors.

[0107] The present invention further provides a photopolymer comprising a photopolymer composition, in particular comprising matrix polymers, a writing monomer, and a photoinitiator system, which additionally contains a compound of formula (XVI). The statements made above regarding the photopolymer composition according to the invention regarding further preferred embodiments also apply analogously to the previously described photopolymer.

[0108] A further object of the present invention relates to a layer structure comprising at least the layers:

[0109] A. a substrate layer A, which may be part of a further layer structure,

[0110] B. a photopolymer layer B, formed from the photopolymer composition according to the invention, and

[0111] C. a cover layer C, which may be part of the further layer structure.

[0112] A further object of the present invention relates to a layer structure comprising at least the layers:

[0113] A. a substrate layer A, which may be part of a further layer structure,

[0114] B' an exposed or light-cured photopolymer layer B' which was produced from the photopolymer composition according to the invention by curing by means of light, and

[0115] C. a cover layer C, which may be part of the further layer structure.

[0116] Furthermore, a method for producing a holographic medium using a disclosed photopolymer composition is disclosed. The photopolymer compositions can be used, in particular, for producing holographic media in the form of a film. 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 coated in the dark on one or both sides with the photopolymer composition B. Optionally, a cover layer C is applied to the photopolymer layer(s) B.Preferred materials or material composites for the carrier 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, 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 A / B, A / B / A, or A / B / C schemes. PC / PET, PET / PC / PET, and PC / TPU (TPU = thermoplastic polyurethane) are particularly preferred. The materials or material composites for the carrier can be anti-adhesive, antistatic, hydrophobic, or hydrophilic on one or both sides.The modifications mentioned serve the purpose of ensuring that the photopolymer layer B can be detached from the carrier A without causing damage. 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, during processing in roll laminators, particularly in roll-to-roll processes.

[0117] Additionally, a further process for producing a holographic medium using a photopolymer composition according to the invention is disclosed, which also yields holographic media in the form of films. In this process, 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 used as carrier A. The photopolymer composition B is applied in the dark on one side using 2D printing, and optionally a cover layer C is applied to 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 A / B, A / B / A, or A / B / C schemes. PC / PET, PET / PC / PET, and PC / TPU (TPU = thermoplastic polyurethane) are particularly preferred. The materials or material composites of the carrier can be non-adhesive, antistatic, hydrophobic or hydrophilic on one or both sides.The modifications mentioned serve the purpose of ensuring that the photopolymer layer B can be detached from the carrier A without causing damage on the side facing the photopolymer layer B. 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 that are required, for example, during processing in roll laminators, particularly in roll-to-roll processes.

[0118] Furthermore, material composites of the type described above are disclosed, comprising a photo-exposed, preferably light-cured photopolymer layer B', so that duplex and triplex films are obtained according to a scheme A / B', A / B' / A or A / B' / C.

[0119] Holographic information can be imprinted into such holographic media.

[0120] The invention further relates to a holographic medium containing a photopolymer composition according to the invention. Holographic media 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.

[0121] Holograms encompass all holograms that can be recorded using methods known to those skilled in the art. These include, among others, in-line (Gabor) holograms, 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. Reflection holograms, Denisyuk holograms, and transmission holograms are preferred.

[0122] Another subject matter of the invention relates to a holographic medium which has been converted into a hologram, wherein 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 and a holographic stereogram, preferably a reflection, transmission or edge-lit hologram or a combination of at least two thereof; combinations of these hologram types or several holograms of the same type can also be combined independently of one another in the same volume of the holographic medium (multiplexing).

[0123] Possible optical functions of the holograms that can be produced with the photopolymer compositions 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.

[0124] Another subject of the invention relates to an optical display comprising a holographic medium according to the invention.

[0125] In addition, holographic media can also be used to create holographic images or representations, such as for personal portraits, biometric representations in security documents, or generally 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 type of light source (including moving ones), etc. Due to these diverse design possibilities, holograms, especially volume holograms, represent an attractive technical solution for the aforementioned applications.

[0126] 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, sensing, LIDAR, augmented reality, head-mounted display and virtual reality applications, in particular in the near infrared range and a combination of at least two thereof.

[0127] 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.

[0128] Holograms are accessible from holographic media according to the invention by appropriate exposure.

[0129] The following examples serve to illustrate the invention without limiting it to them.

[0130] Measurement methods:

[0131] OH number: The stated OH numbers were determined according to DIN 53240-2.

[0132] NCO value: The stated NCO values ​​(isocyanate contents) were determined according to DIN EN ISO 11909.

[0133] Measurement of the holographic properties DE and An of the holographic media using

[0134] Two-beam interference in reflection arrangement:

[0135] 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). The final cross-sections of the signal and reference beams are determined by the iris diaphragms (I). The diameter of the iris diaphragm opening is 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 is -22.0°, and the angle of incidence (β0) of the signal beam is 42.0°. The angles are measured from the sample normal to the beam direction. According to Figure 1, α0 has a negative sign andβ0 has a positive sign.At the sample location (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 Λ, also called the grating period, in the medium is ~225 nm (assuming the refractive index of the medium to be ~1.504).

[0136] Figure 1 shows the holographic experimental setup used to measure the diffraction efficiency (DE) of the media, where the geometry of a Holography Media Tester (HMT) at λ = 457 nm (DPSS laser) is shown (M = mirror, S = shutter, SF = spatial filter, CL = collimator lens, λ / 2 = λ / 2 slat, 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 medium), RD = reference direction of the turntable).

[0137] Holograms were written into the medium in the following way:

[0138] • Both shutters (S) are open for the exposure time t.

[0139] • Afterwards, with the shutters closed (S), the medium was allowed 5 minutes for the diffusion of the not yet polymerized writing monomers.

[0140] The recorded holograms were then read out as follows: The shutter of the signal beam remained closed. The shutter of the reference beam was opened. The iris of the reference beam was closed to a diameter of < 1 mm. This ensured that for all rotation angles (Ω) of the medium, the beam always lay completely within the previously recorded hologram. The turntable then covered the angular range of Ω under computer control. min to Ω maxwith an angular increment of 0.05°. Ω is measured from the sample normal to the reference direction of the rotary table. The reference direction of the rotary table is determined when the angle of incidence of the reference and signal beams are equal when writing the hologram, i.e., α0 = -32° and β0 = 32°. Then Ω is recording = 0°. For α0= -22.0° and β0= 42.0°, Ω recording hence 10°. In general, the interference field during recording of the hologram is: α0= θ0+ Ω recording . (2) θ0 is the half-angle in the laboratory system outside the medium and the following applies when writing the hologram:

[0141] 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 at each angle Ω was determined as the quotient of:

[0142] P D is the power in the detector of the diffracted beam and P T is the power in the detector of the transmitted beam.

[0143] Using the procedure 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. The maximum diffraction efficiency (DE = ηmax) 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.

[0144] The refractive index contrast Δn and the thickness d of the photopolymer layer 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) based on 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 Λ 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 recording This changes the Bragg condition. This change is taken into account in the evaluation procedure. The evaluation procedure is described below:

[0145] All geometric quantities that refer to the written hologram and not to the interference pattern are represented as primed quantities.

[0146] According to Kogelnik, the Bragg curve η (Ω) of a reflection hologram is: with:

[0147] When reading the hologram (“reconstruction”), the following applies as shown above: ϑ'0= θ0+Ω

[0148] (13) sin(ϑ'0) = n sin(ϑ') (14)

[0149] At the Bragg condition, the dephasing is DP = 0. And it follows accordingly: α'0= θ0+ Ω reconstruction

[0150] (15) sin(α'0) = n • sin(α') (16)

[0151] The still unknown angle β' can be determined from the comparison of the Bragg condition of the interference field when writing the hologram and the Bragg condition when reading the

[0152] hologram can be determined assuming that only thickness shrinkage occurs. Then it follows: v is the lattice strength e, ξ is the detuning parameter, and ψ' is the orientation (slant) of the refractive index grating being written. α' and β' correspond to the angles α0 and β0 of the interference field during writing of the hologram, but measured in the medium and valid for the hologram grating (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.

[0153] The maximum diffraction efficiency (DE = η max ) then results for ξ = 0:

[0154] 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 = α' o — ϑ'0, also called angle detuning (x-axis), is plotted. Figure 2 shows the measured transmitted power P T(right y-axis) plotted as a solid line (here of example 27b) against the angular detuning ΔΩ, the measured diffraction efficiency η (left y-axis) plotted as filled circles against the angular 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).

[0155] Since DE is known, the shape of the theoretical Bragg curve according to Kogelnik is determined solely by the thickness cT 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.

[0156] Since the direction in which a reflection hologram rotates during reconstruction using a Q-scan, but 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'.

[0157] 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.

[0158] For a formulation, this procedure may have been repeated several times for different exposure times t on different media 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):

[0159] The powers of the partial beams were adjusted so that the same power density is achieved in the medium at the used angles α0 and β0.

[0160] Calculation of the reduction potential of triarylalkyl borates:

[0161] The absolute reduction potential referenced against the saturated calomel electrode, was calculated using the following formula (20):

[0162] Where n e the number of transferred electrons (here always n e = 1), F is the Faraday constant (F =

[0163] 23.061 kcal mol -1 V -1 ), the absolute potential value of the standard hydrogen electrode (SHE) the potential of the saturated calomel electrode (SCE) relative to the SHE in

[0164] Acetonitrile ) and G 298 and G 298 (oxidized) the calculated Gibbs energies at

[0165] 298 K of the ground state and the oxidized state of the coinitiator, in particular the triarylalkyl borate. Formula (20) can also be expressed as follows after inserting the above-mentioned constants (Formula (1)):

[0166] The calculation of the Gibbs energies at 298 K of the ground state and the oxidized state was carried out according to the following procedure: First, the three-dimensional molecular geometry of the coinitiator, in particular the triarylalkyl borate, was generated using ChemDraw 3D and subjected to conformer analysis. The found conformers were energetically minimized using the AMI force field, and the obtained coordinates of the molecular geometries (usually only one conformer was obtained) were used to calculate the electronic energy. The electronic ground state was geometry-optimized in a suitable solvent (PCM approach for acetronitrile), and the absolute electronic energies of the optimized structures were determined and corrected for the influence of the solvent field (G 298). The optimized molecular geometry was then reduced by one electron and the absolute electronic energy of the oxidized molecule was determined again, also calculated in acetonitrile (PCM method) (G 298 (oxidized)).

[0167] Substances:

[0168] 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.

[0169] Polyol 1 was prepared as described in WO2015091427 with an OH number of 56.8.

[0170] Desmodur® N 3900 product of Covestro AG, Leverkusen, DE, hexane diisocyanate-based polyisocyanate, iminooxadiazinedione content at least 30%, NCO content: 23.5%.

[0171] Urethane acrylate 1 (phosphorothioyltris(oxybenzene-4,1-diylcarbamoyloxyethane-2,1-diyl)trisacrylate, [1072454-85-3]) was prepared as described in WO2015091427.

[0172] Urethane acrylate 2 (2-({[3-(methylsulfanyl)phenyl]carbamoyl}oxy)-ethylprop-2-enoate, [1207339-61-4]) was prepared as described in WO2015091427.

[0173] Dye 1 (1,3,3-trimethyl-2-[2-(1-methyl-2-phenyl-1H-indol-3-yl)ethenyl]-3H-indoliumbis(2-ethylhexyl)sulfobsuccinic acid ester)) was prepared as described in WO 2012062655.

[0174] Additive 1 (bis(2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl)-(2,2,4-trimethylhexane-1,6-diyl)biscarbamate, [1799437-41-4]) was prepared as described in WO2015091427. Iron(III) trifluoroacetylacetonate [14526-22-8] is available from ABCR GmbH & Co. KG, Karlsruhe, Germany.

[0175] BYK®-310 Silicone-containing surface additive, product of BYK-Chemie GmbH, Wesel, Germany.

[0176] Tinuvin® 400 UV absorber, product of BASF SE, Ludwigshafen, Germany.

[0177] Cation 2 (N1, N 22 -Dihexadecyl-N1,N1, N 22 , N 22 , 10, 10, 13-heptamethyl-7, 16-dioxo- 3,6,17,20-tetraoxa-8, 15-diazadocosane- 1 ,22-diaminium dibromide) was prepared as described in WO 2018087064.

[0178] synthesis instructions;

[0179] Manufacturing instructions for N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium chloride

[0180] (Cation 1):

[0181] 1.28 mol of dimethylcetylamine was dissolved in 2.4 L of tert-butyl methyl ether (MTBE) at 30 °C in a 5 L flat-ground vessel. 1.28 mol of 3-chlorophenylpropane was added dropwise to this solution at a rate such that the reaction temperature did not exceed 40 °C. After the addition was complete, the reaction solution was stirred at 90 °C for 5 h, then cooled to 40 °C over a period of 1 h and transferred to suitable vessels for crystallization. The crystals that formed overnight were isolated, washed with 500 mL of cold MTBE, and dried. A colorless solid was obtained (450 g, 83% of theory) with a melting point of 59 °C.

[0182] Preparation instructions for tetrabutylammonium triarylalkyl borates with R 101 =R 102 =R 103 :

[0183] The corresponding diisopropyl alkyl borate (1.0 eq.) and magnesium turnings (3 eq.) were placed in a solvent mixture consisting of dry toluene and dry THF (5.8:1, 1.9 M) in a four-necked flask equipped with a thermometer, reflux condenser, dropping funnel, and magnetic stirrer. This mixture was stirred at room temperature for 30 min. The corresponding aromatic bromide (3 eq.) was then added dropwise to the mixture undiluted until an exothermic reaction signaled the start of the reaction. However, a maximum of 10% of the undiluted aromatic bromide was used for this purpose. The remainder of the aromatic bromide was added dropwise to the reaction solution in a solvent mixture consisting of dry toluene and dry THF (1:1, dilution of the total molarity to 0.4 M) at a rate that did not exceed 45 °C. After the addition was complete, the reaction solution was heated under reflux for 1 h until the magnesium was completely dissolved.The reaction solution was cooled to room temperature and poured into a mixture of ice water and tetrabutylammonium bromide (1 eq.). The mixture was stirred for 1 h, after which the organic phase was separated. The organic phase was washed with water until a halide test (HNO3 (aq., 10%) + AgNO3) was negative. The solvents were removed in vacuo using a rotary evaporator, and the crude product was recrystallized from methanol.

[0184] Preparation instructions for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 103 :

[0185] The corresponding diisopropylalkylborate (1.0 eq.) and magnesium turnings (3 eq.) were placed in a solvent mixture consisting of dry toluene and dry THF (4:1, 1.9 M) in a four-necked flask equipped with a thermometer, reflux condenser, dropping funnel, and magnetic stirrer. This mixture was stirred at room temperature for 30 min. The first bromoaromatic compound (1 eq.) was then added dropwise undiluted to the mixture until an exothermic reaction signaled the start of the reaction. However, a maximum of 10% of the undiluted bromoaromatic compound was used for this purpose. The remainder of the bromoaromatic compound was added dropwise to the reaction solution in a solvent mixture consisting of dry toluene and dry THF (1.1:1, dilution of the total molarity to 0.7 M) at a rate such that the reaction temperature did not exceed 45 °C. After the addition was complete, the reaction solution was stirred at room temperature for 1 h.The corresponding second aromatic bromide was then added dropwise to the mixture undiluted until the onset of an exothermic reaction signaled the start of the reaction. However, a maximum of 10% of the undiluted aromatic bromide was used for this purpose. The remainder of the aromatic bromide was again added dropwise to the reaction solution in the remaining solvent mixture consisting of dry toluene and dry THF (1.1:1, dilution of the total molarity to 0.4 M) in such a way that the reaction temperature did not exceed 45 °C. After the addition was complete, the reaction solution was heated under reflux until the magnesium had completely dissolved or for 1 h. The reaction solution was cooled to room temperature and poured onto a mixture consisting of ice water and tetrabutylammonium bromide (1 eq.). The mixture was stirred for 1 h, and the organic phase was separated. The organic phase was washed with water until a halide test (HNO3 (aq., 10%) + AgNO3) was negative.The solvents were removed in vacuo using a rotary evaporator and the crude product was recrystallized from methanol.

[0186] Preparation instructions for triarylalkyl borates with cations of valence n=1:

[0187] The corresponding tetrabutylammonium triarylalkylborate (1 eq.) was dissolved in butyl acetate (0.04 M) and treated with an aqueous solution of the corresponding cation (halide salt, 1.05 eq., 0.05 M) and sodium bis(2-ethylhexyl)sulfosuccinate (0.05 eq.). The mixture was stirred at RT for 1 h. After phase separation, the organic phase was washed with water until a halide test (HNO3(aq., 10%) + AgNO3) was negative. The solvent was removed in vacuo using a rotary evaporator, and the product was dried under vacuum.

[0188] Preparation procedure for triarylalkyl borates with cations of valence n=2:

[0189] The corresponding tetrabutylammonium triarylalkylborate (1 eq.) was dissolved in butyl acetate (0.04 M) and treated with an aqueous solution of the corresponding cation (halide salt, 0.525 eq., 0.05 M) and sodium bis(2-ethylhexyl)sulfosuccinate (0.05 eq.), and the mixture was stirred at RT for 1 h. After phase separation, the organic phase was washed with water until a halide test (HNO3(aq., 10%) + AgNO3) was negative. The solvent was removed in vacuo using a rotary evaporator, and the product was dried under vacuum.

[0190] Manufacturing instructions for photopolymer film / holographic media:

[0191] 12.4 g of the polyol component 1 described above were melted and mixed in the dark with 6.6 g of urethane acylate 1, 6.6 g of urethane acrylate 2 described above, 9.2 g of the fluorinated urethane (additive 1) described above, 0.86 g of the respective borate salt described above, 0.14 g of dye 1, 0.12 g of BYK 310, 0.01 g of iron(III) trifluoroacetylacetonate, 2.4 g of the additive Tinuvin® 400, and 19.2 g of ethyl acetate to obtain a clear solution. Subsequently, 2.3 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.

[0192] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(3-fluorophenyl)hexylborate:

[0193] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 =R 103 3-Fluorobromobenzene was reacted with diisopropylhexyl borate. Following the general preparation procedure for triarylalkyl borates with cations of valence n=1, the resulting tetrabutylammonium triarylalkyl borate was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (0.72 g, 2% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.28 V vs. SCE in acetonitrile.

[0194] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium tri-(3-fluorophenyl)-hexylborate (Example 16 in Table 2):

[0195] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using 7V-benzyl-N,N-dimethylhexadecylammonium tri-(3-fluorophenyl)hexylborate as coinitiator.

[0196] Preparation of N-benzyl-1-dimethylhexadecylammonium-3-chlorophenoxydi-(3-fluorphenoxy)hexyl-borate:

[0197] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 #R 1033-chlorobromobenzene (1 eq.) and 3-fluorobromobenzene (2 eq.) were reacted with diisopropylhexylborate. Following the general preparation procedure for triarylalkylborates with cations of valence n=1, the resulting tetrabutylammonium triarylalkylborate was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (3.8 g, 24% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.29 V vs.

[0198] SCE in acetonitrile.

[0199] Preparation of a photopolymer with N-benzyl-NN-dimethylhexadecylammonium-3-chlorophenyldi-

[0200] (3-fluorophenyl)hexylborate (Example 22 in Table 2):

[0201] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium 3-chlorophenyldi-(3-fluorophenyl)hexylborate as coinitiator.

[0202] Preparation of tetrabutylammonium tri-(3-chlorophenyl)hexylborate:

[0203] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 =R 103 3-chlorobromobenzene was reacted with diisopropylhexylborate. Colorless crystals (56 g, 50% of theory) were obtained with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -9.9 ppm. The calculated reduction potential was E ox = 1.32 V vs. SCE in acetonitrile.

[0204] Preparation of a photopolymer with tetrabutylammonium tri-(3-chlorophenyl)hexylborate (Example 27a in Table 2):

[0205] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using tetrabutylammonium tri-(3-chlorophenyl)hexylborate as coinitiator.

[0206] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chlorophenyl)hexylborate:

[0207] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 =R 103 3-chlorobromobenzene was reacted with diisopropylhexyl borate. The general preparation procedure for triarylalkyl borates with cations of valence n=1 was then followed using N-benzyl-A,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (2.5 g, 50% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.32 V vs. SCE in acetonitrile.

[0208] Preparation of a N-benzyl-N, N-dimethylhexadecylammonium tri-(3-chlorophenyl)hexylborate (Example 27b in Table 2):

[0209] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared with N-benzyl-A, N-dimethylhexadecylammonium tri-(3-chlorophenyl)hexylborate as coinitiator.

[0210] Preparation of N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium chloride (cation 1):

[0211] 1.28 mol of dimethylcetylamine was dissolved in 2.4 L of tert-butyl methyl ether (MTBE) at 30 °C in a 5 L flat-ground vessel. 1.28 mol of 3-chlorophenylpropane was added dropwise to this solution at a rate such that the reaction temperature did not exceed 40 °C. After the addition was complete, the reaction solution was stirred at 90 °C for 5 h, then cooled to 40 °C over a period of 1 h and transferred to suitable vessels for crystallization. The crystals that formed overnight were isolated, washed with 500 mL of cold MTBE, and dried. A colorless solid was obtained (450 g, 83% of theory) with a melting point of 59 °C.

[0212] Preparation of N-(3-phenylpropyl)-N,N-dimethylhexadecylammonium tri-(3-chlorophenyl)-hexylborate:

[0213] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 =R 1033-chlorobromobenzene was reacted with diisopropylhexylborate. The general preparation procedure for triarylalkyl borates with cations of valence n=1 was then followed using cation 1. A colorless oil (2.6 g, 50% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.32 V vs. SCE in acetonitrile.

[0214] Preparation of a photopolymer with N,N-dimethyl-N-(3-phenylpropyl)hexadecylammonium tri-(3-chlorophenyl)hexylborate (Example 27c in Table 2):

[0215] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N,N-dimethyl-N-(3-phenylpropyl)hexadecylammonium tri-(3-chlorophenyl)hexylborate as coinitiator.

[0216] Preparation of tributyltetradecylphosphonium tri-(3-chlorophenyl)hexylborate:

[0217] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 =R 103 3-chlorobromobenzene was reacted with diisopropylhexylborate. The general preparation procedure for triarylalkylborates with cations of valence n=1 was then followed using tributyltetradecylphosphonium bromide. A colorless oil (0.86 g, 33% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.32 V vs. SCE in acetonitrile.

[0218] Preparation of a photopolymer with tributyltetradecylphosphonium tri-(3-chlorophenyl)hexylborate

[0219] (Example 27d in Table 2):

[0220] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using tributyltetradecylphosphonium tri-(3-chlorophenyl)hexylborate as coinitiator.

[0221] Preparation of tetraoxa-8,15-diazadocosane-L22-diaminium bis-tri(3-chlorophenyl)hexylborate:

[0222] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 =R 103 3-chlorobromobenzene was reacted with diisopropylhexylborate as the bromoaromatic compound. The general preparation procedure for triarylalkylborates with cations of valence n=2 was then followed using cation 2. A colorless oil (3.98 g, 48% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.32 V vs. SCE in acetonitrile. Preparation of a photopolymer with N1, N 22 -Dihexadecyl-N1,N1,N 22 .N 22 .10.10.13-heptamethyl-7.16-dioxo-3.6.17.20-tetraoxa-8, 15-diazadocosan-L22-diaminium-bis-tri(3-chlorophenvl)hexvl borate

[0223] (Example 27e in Table 2):

[0224] According to the general manufacturing procedure for photopolymer films, a photopolymer with N1, N 22 -Dihexadecyl-N1, N1, N 22 , N 22 , 10, 10,13-heptamethyl-7, 16-dioxo-3,6, 17,20-tetraoxa-8, 15-diazadocosane-l,22-diaminium-bis-tri(3-chlorophenyl)hexylborate as coinitiator.

[0225] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chlorophenyl)butylborate:

[0226] According to the general manufacturing procedure for tetrabutylammonium triarylbutylborates with R 101 =R 102 =R 1033-chlorobromobenzene was reacted with diisopropylbutylborate. Following the general preparation procedure for triarylalkylborates with cations of valence n=1, the resulting tetrabutylammonium triarylbutylborate was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (4.63 g, 49% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ ( ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.32 V vs. SCE in acetonitrile.

[0227] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chlorophenyl)butylborate (Example 28 in Table 2):

[0228] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chlorophenyl)butylborate as coinitiator.

[0229] Preparation of N-benzyl-N,N-dimethylhexadecylammonium di-(3-chlorophenyl)-3-fluorophenylhexyl borate:

[0230] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 #R 103 3-chlorobromobenzene (2 eq.) and 3-fluorobromobenzene (1 eq.) were reacted with diisopropylhexylborate. The general preparation procedure for triarylalkylborates with cations of valence n=1 was then followed using N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (3.0 g, 29% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.34 V vs. SCE in acetonitrile.

[0231] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium di-(3-chlorophenyl)-

[0232] 3-fluorophenylhexylborate (Example 32 in Table 2):

[0233] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium di-(3-chlorophenyl)-3-fluorophenylhexylborate as coinitiator.

[0234] Non-inventive examples (NEB):

[0235] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)-hexylborate: The preparation procedure as published in WO 2018 / 099698 was used. The calculated reduction potential was E ox = 1.15 V vs. SCE in acetonitrile.

[0236] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)-hexylborate (example NEB-1 in Table 2):

[0237] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)-hexylborate as coinitiator.

[0238] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(4-trifluoromethoxy-phenyl)dodecylborate:

[0239] The manufacturing procedure published in WO 2018 / 087064 was followed. The calculated reduction potential was E ox = 1.38 V vs. SCE in acetonitrile.

[0240] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium tri-(4-trifluoromethoxyphenyl)dodecylborate (example NEB-2 in Table 2):

[0241] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared with N-benzyl-N,N-dimethylhexadecylammonium tri-(4-trifluoromethoxy-phenyl)dodecylborate as coinitiator.

[0242] Preparation of N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium tri-(4-trifluoromethyl-phenyl)-hexylborate:

[0243] According to the general manufacturing procedure for tetrabutylammonium triarylhexylborates with R 101 =R 102 =R 1033-Bromobenzene trifluoride was reacted with diisopropylbutylborate. The general preparation procedure for triarylalkyl borates with cations of valence n=1 was then followed using cation 1. A colorless oil (2.5 g, 22% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.0 ppm. The calculated reduction potential was E ox = 1.45 V vs. SCE in acetonitrile.

[0244] Preparation of a photopolymer with N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium tri-(4-trifluoromethylphenyl)hexylborate (example NEB-3 in Table 2):

[0245] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium tri-(4-trifluoromethylphenyl)hexylborate as coinitiator.

[0246] Examples

[0247] The oxidation potential of various trialkylarylborates according to the invention and not according to the invention was determined using the above-mentioned method for calculating the oxidation potential of triarylalkylborates using the software package GAMESS (G. MJ. Barca, C. Bertoni, L. Carrington, D. Datta, N. De Silva, JE Deustua, DG Fedorov, JR Gour, AO Gunina, E. Guidez, T. Harville,

[0248] S. Irle, J. Ivanic, K. Kowalski, SS Leang, H. Li, WL, JJ Lutz, I. Magoulas, J. Mato, V. Mironov, H. Nakata, BQ Pham, P. Piecuch, D. Poole, SR Pruitt, AP Rendell, LB Roskop, K. Ruedenberg,

[0249] T. Sattasathuchana, MW Schmidt, J. Shen, L. Slipchenko, M. Sosonkina, V. Sundriyal, A. Tiwari, JL Galvez Vallejo, B. Westheimer, M. Wloch, P. Xu, F. Zahariev, M.S. Gordon; J. Chem. Phys. 152; 154102 (2020).). The results of these calculations are listed in the table below. The cation of the corresponding trialkylarylborate is irrelevant for the calculation of the oxidation potential, so the values ​​listed below apply to salts of the following general structure: where K + or K 2+ represent any ammonium or phosphonium cation.

[0250]

[0251] Based on formula (II), the radical designations R 100 from Table 1 the remainder AR 100 in formula (II), the radicals R 101 , R 102 and R 103 on the aromatic compound from Table 1, the residue(s) R 101 , R 102and R 103 from formula (II) as shown in the following Table la.

[0252]

[0253]

[0254] Evaluation of the thermal stability of photopolymer films with coinitiators according to the invention;

[0255] The requirements for the photopolymer films produced here are both a low loss of photoactivity after a tempering step and complete bleachability of the

[0256] Photopolymer film after holographic exposure. This was verified as follows: First, two samples were prepared identically for each example. The preparation involved removing the lamination film of the photopolymer layer structure and subsequently laminating the resulting unprotected side of the photopolymer onto a glass plate, resulting in a glass-photopolymer substrate film layer structure. A transmission spectrum (T 1,RT ). The second sample, later referred to as the tempering sample (Temp), was tempered for 30 min at 140 °C in a drying cabinet. After the tempering step, a transmission spectrum (T 1,Temp). Consequently, using a two-beam interference laser setup as shown in Figure 1 and previously described, a test hologram was inscribed into the photopolymer layer of both samples using a 457 nm laser. The quality of this hologram was assessed based on the refractive index modulation Δn of the sample, derived from the readout diffraction efficiency and its angular selectivity. Subsequently, both samples were bleached comprehensively for 30 min under UV light irradiation. A transmission spectrum (T 2,RT and T 2,TemP ). The thermal stability combined with high bleachability of a photopolymer was evaluated based on three criteria, all of which must be met simultaneously. The three fulfillment criteria are described in detail below:

[0257] 1. Thermostability evaluated by transmission loss TS(T): The ratio of the transmission at the absorption maximum of the dye used (here 510 nm) after the tempering step of the temp sample T 1, Temp, 510 to the transmission of the RT sample at the same wavelength T 1,RT,510 must be greater than 50%. The transmission values ​​must be corrected for background absorption caused by turbidity or similar (here the transmission at 730 nm is used as a reference value) (T 2, Temp, 730 ):

[0258] 2. Thermostability evaluated according to Δn: TS(Δn): The refractive index difference Δn of the temp sample must be greater than 0.007:

[0259] TS (Δn) = Δn Temp > 0.007 (22)

[0260] 3. Bleachability assessed by residual absorption B(T): The ratio of the transmission after bleaching with UV light of the Temp sample (T 2,Temp,510 ) to the original transmission of the RT sample (T 1,RT,510) must be less than or equal to 15%. Again, the transmission values ​​must be corrected for background absorption caused by turbidity or similar (T 2,Temp,730 ):

[0261] The following transmission and Δn values ​​of some inventive and non-inventive

[0262] Examples were determined: Table 2. Measured transmission and An values ​​of the inventive and non-inventive examples, as well as the ratings calculated therefrom. TI.RT.510 : Transmission of the RT sample at 510 nm; Ti,Temp,5io: Transmission of the Temp sample at 510 nm; T2.Temp.730: Background transmission determined at 730 nm; TS(T): Evaluation of thermostability after transmission loss; TS(An): Evaluation of thermostability after An; B(T): Evaluation of bleachability after residual transmission.

[0263] 16 1.28 40 50 85 92 80 0.0155 13

[0264] 22 1.29 47 53 87 92 87 0.0071 11

[0265] 27a 1.32 45 52 89 92 85 0.0146 6

[0266] 27b 1.32 50 56 89 92 86 0.0158 8

[0267] 27c 1.32 43 52 88 92 83 0.0180 8

[0268] 27d 1.32 44 49 84 91 90 0.0180 15

[0269] 27e 1.32 43 47 85 91 92 0.0222 13

[0270] 28 1.32 48 55 88 92 83 0.0175 9

[0271] 32 1.34 39 42 84 92 94 0.0224 14

[0272] NEB1 1.15 44 73 87 92 39 0 9

[0273] NEB2 1.38 46 54 61 91 80 0 65

[0274] NEB3 1.45 43 44 60 91 99 0.01 65

[0275] * vs. SCE in acetonitrile; calculated;

[0276] The results obtained show that the required properties of thermal stability and bleachability of a photopolymer are achieved with the triarylalkyl borate salts according to the invention. A photopolymer can therefore only be considered sufficiently thermally stable and bleachable if the calculated oxidation potential of the borate salt used is greater than 1.15 V and less than 1.38 V vs. SCE in acetonitrile. The use of all borates listed in Table 1 as coinitiators in photopolymers therefore leads to thermally stable and bleachable photopolymers. The thermal stability and bleachability of the photopolymer do not depend on the cation used in the borate salt, as a comparison of Examples 27a to 27e illustrates. A variation of the alkyl radical of the triarylalkyl borate salt is also possible without loss of thermal stability and bleachability of the photopolymer, as a comparison of Examples 27b and 28 demonstrates.

[0277] The non-inventive examples NEB1, NEB2 and NEB3 fail in at least one required property and are therefore unsuitable for providing the required properties.

Claims

Patent claims 1. A photopolymer composition comprising a) matrix polymers, b) writing monomers, c) at least one photoinitiator system, d) optionally at least one non-photopolymerizable component, e) optionally catalysts, radical stabilizers, solvents, additives and other auxiliary and / or additives, wherein the at least one photoinitiator system c) consists of at least one dye and at least one co-initiator, wherein at least one of the dyes has a structure according to formula (I) wherein R 201 optional; if available for hydrogen, C1 to C 16 -Alkyl, C3 to C6 alkenyl, C5 to C7 cycloalkyl or C7 to C 16 -Aralkyl or C6- to C 10 -Aryl stands, R 203 for C1 to C 16 -Alkyl, C3 to C6 alkenyl, C5 to C7 cycloalkyl or C7 to C 16 -Aralkyl or C6- to C 10 -Aryl stands, R202 for hydrogen, C1 to C 16 -Alkyl, C3 to C6 alkenyl, C5 to C7 cycloalkyl or C7 to C 16 -Aralkyl, C6- to C 10 -Aryl or Hetaryl stands for R 204 stands for hydrogen, C1- to C4-alkyl, C1- to C4-alkoxy, halogen, cyano, nitro or C1- to C4-alkoxycarbonyl, A together with X 1 and X 2 and the one between X 1 and X 2 The bonded carbon atom represents a five- or six-membered aromatic or quasi-aromatic or partially hydrogenated heterocyclic ring, which may contain 1 to 4 heteroatoms and / or be benz- or naphthanel-fused and / or substituted by nonionic residues. X 2 for N, O or S, preferably for N, and X 1 for O, S, CR 205 R 206 or -CH=CH- stands, preferably for CR 205 R 206 stands, whereby R 205 and R 206independently for C1 to C4 alkyl, C3 to C6 alkenyl, C4 to C7- Cycloalkyl, C7- to C 10 -Aralkyl or C6-aryl are and An- represents an anion of the selection halide, perchlorate, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, tetraarylborate, triarylalkylborate, nitrate, cyanide, tosylate, trifluoromethylsulfonate, bis(trifluoromethyl)sulfonimide, azide, methylsulfonate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, hydrogen sulfate, any substituted carboxylate, any substituted organic mono- or disulfonate, or any substituted organic mono- or dicarboxylate, and the at least one coinitiator has a calculated oxidation potential. according to the formula (1) below, by quantum mechanical calculation of the Gibbs energies at 298 K of the ground state and the oxidized state of the co-initiator, in particular the triarylalkyl borate, after geometry optimization, consisting of conformer energy minimization using the AMI force field followed by ab initio conformer energy calculation starting from the previously determined molecular geometry coordinates, in the solvent acetonitrile under solvent field correction according to the PCM method, in the range of 1.16 V to 1.37 V against the saturated calomel electrode (SCE) in acetonitrile (1) 2. The photopolymer composition according to claim 1, wherein the at least one dye according to the structure of formula (I) comprises the following residues: R 201 is optional; if present, stands for hydrogen, methyl, ethyl, propyl, butyl, benzyl or phenethyl, R 203stands for methyl, ethyl, propyl, butyl, benzyl or phenethyl, R 202 stands for hydrogen, methyl or phenyl, R 204 stands for hydrogen, methyl, ethyl, cyclohexyl, phenyl, tolyl, anisyl or chlorophenyl, A together with X 1 and X 2 and the carbon atom bonded between them for pyridin-2-ylene or pyridin-4-ylene, quinolin-2-ylene or quinolin-4-ylene, l,3-thiazolin-2-ylene, l,3-thiazolin-2-ylene, benzothiazol-2-ylene, l,3,4-thiadizol-2-ylene, l,3-oxazolin-2-ylene, Benzoxazol-2-ylene, imidazol-2-ylene, imidazolin-2-ylene, benzimidazol-2-ylene, pyrrolin-2-ylene, 1,3,4-triazol-2-ylene, 3-H-indol-2-ylene or quinoxalin-2-ylene, which is substituted by methyl, ethyl, benzyl, methoxy, chlorine, cyano, nitro or methoxycarbonyl are, whereby in the case of imidazol-2-ylene, Imidazolin-2-ylene and benzimidazol-2-ylene both have nitrogen atoms substituted by R41b, and in the case of 1,3,4-thiadizole-2-ylene, the substituents are selected from the Group consisting of dimethylamino, diethylamino, dipropylamino, dibutylamino, N-methyl, N-cyanoethylamino, bis(cyanoethyl)amino, N-methyl-N-phenylamino, pyrrolidines, piperidino and morpholino, or A together with X 1 and X 2 and the intervening C atom stands for 2H-pyran-2-ylene, 4H-pyran-4-ylene, 2H-thiopyran-2-ylene, 4H-thiopyran-4-ylene, which are substituted by two residues of the group phenyl, tolyl or anisyl.

3. The photopolymer composition according to one of the preceding claims, wherein the at least one dye has a structure of formula (XVII), in which R 201 and R 203 Each can stand independently for methyl, ethyl or benzyl, and R 202 stands for hydrogen, methyl, or phenyl.

4. The photopolymer composition according to one of the preceding claims, wherein the at least one dye present according to formula (I) or formula (XVII) comprises an organically substituted sulfonate as the anion (An-).

5. The photopolymer composition according to any of the preceding claims, wherein the at least one coinitiator is a triarylalkylborate salt.

6. The photopolymer composition according to one of the preceding claims, wherein the at least one coinitiator comprises a triarylalkyl borate of formula (II), wherein A for a methylene group or for any substituted methine group, optionally with R 100 forming a ring with up to 10 segments, stands R 100 for hydrogen or a C1- to C-substituted compound, optionally with hydroxy and / or alkoxy and / or acyloxy and / or halogen 20 -Alkyl-, C3- to C 12 -Alkyl group, C3- to C 20-Alkenyl-, C3- to C 20 -Alkynyl-, C5- to C7-cycloalkyl- or C7- to C 13 -aralkyl group is present, R, R 102 , and R 103 independently of each other for up to five independently selected residues from C1 to C 10 -Alkyl-, C3- to C5-alkenyl-, C3- to C5-alkynyl-, C5- to C7-cycloalkyl- or C7- to C 13 -Aralkyl radical, halogen, cyano, trifluoromethyl, trichloromethyl, difluoromethyl, dichloromethyl, trifluoromethylthioyl, trichloromethylthioyl, C1 to C4 alkoxy, trifluoromethoxy, trichloromethoxy, C1 to C4 alkylthioyl, thioyl, difluoromethoxy, difluoromethylthioyl, carboxyl, carbonyl, 2-, 3-, or 4-pyridyl, or any substituted aryl radicals or hydrogen, K + for any substituted organocation of valence n based on nitrogen, phosphorus, oxygen, sulfur, and / or iodine, and n stands for 1, 2, or 3.

7. The photopolymer composition according to claim 6, wherein the at least one co-initiator of formula (II) comprises the following residues: R 100 for a C1 to C 20 -Alkyl-, C3- to C 12 -Alkyl group, C5- to C7-cycloalkyl or C7- to C 13 - Aralkyl group stands and R 101 , R 102 , and R 103 independently of each other, one or two residues are selected from the group consisting of C1 to C4 alkyl, halogen, cyano, trifluoromethyl, C1 to C4 alkoxy or arbitrarily substituted aryl residues and hydrogen.

8. The photopolymer composition according to claim 6 or 7, wherein R 100 for a C3 to C 12 -Alkyl group is present and R 101 , R 102 , and R 103independently of each other, one or two residues in meta or para position are selected from the group consisting of C1 to C4 alkyl residues and halogen substituents.

9. The photopolymer composition according to any one of the preceding claims, wherein the organocation K + of the triarylalkylborate salt is a nitrogen- or phosphorus-based mono- or divalent cation, preferably a nitrogen-based mono- or divalent cation, and particularly preferably a monovalent ammonium cation.

10. The photopolymer composition according to any of the preceding claims, wherein the at least one coinitiator has an oxidation potential in a range between 1.20 V vs. SCE and 1.36 V vs. SCE in acetonitrile, preferably between 1.25 V and 1.35 V and particularly preferably between 1.28 V and 1.34 V vs. SCE in acetonitrile.

11. A layered structure comprising at least the following layers: A. a substrate layer A, which may be part of a further layer structure, B. a photopolymer layer B formed from the photopolymer composition according to one of the preceding claims, and C. a top layer C, which may be part of a further layer structure.

12. A layered structure comprising at least the following layers: A. a substrate layer A, which may be part of a further layer structure, B' a cured photopolymer layer B' produced from the photopolymer composition according to any one of claims 1 to 10 by curing with light, and C. a top layer C, which may be part of a further layer structure.

13. A holographic medium comprising a photopolymer composition according to any one of claims 1 to 10.

14. Holographic medium according to claim 13, which has been converted into a hologram by exposure, wherein 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 and a holographic stereogram, preferably a reflection, transmission or edge-lit hologram or a combination of at least two thereof, combinations of these hologram types or several holograms of the same type can also be combined independently of one another in the same volume of the holographic medium (multiplexing).

15. Optical display comprising a holographic medium according to claim 13 or 14.

16. Use of a holographic medium according to claim 13 or 14 for the manufacture of chip cards, identity documents, 3D images, product protection labels, labels, banknotes or holographic optical elements, in particular for optical displays or in media for the realization of methods selected from the group consisting of eye-tracking, sensing, LIDAR, augmented reality, head-mounted display and virtual reality applications, in particular in the near-infrared range and a combination of at least two thereof.

17. Use of a photopolymer composition according to any one of claims 1 to 10 for the production of a holographic medium.

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