Triarylalkyl borate salts as coinitiators in nir photopolymer compositions

Abstract

The invention relates to photopolymer compositions 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 agents and / or admixtures, wherein the at least one photoinitiator system c) consists of at least one dye and at least one coinitiator, at least one of the dyes has a structure according to formula (II), and the at least one coinitiator has a calculated oxidation potential (A) which is ascertained according to the formula (1) indicated below by means of a quantum mechanical computation of the Gibbs free energy of the base state and the oxidized state of the triarylalkyl borate at 298 K after a successful geometry optimization, consisting of a compliant energy minimization by means of the AMI force field followed by an ab initio compliant energy computation on the basis of the previously ascertained molecular geometry coordinates, in the solvent acetonitrile using a solvent field correction according to the PCM method, ranging from 1.01 V to 1.31 V with respect to the calomel electrode (SCE) saturated in acetonitrile (1).

Description

[0001] Triarylalkyl borate salts as coinitiators in NIR photopolymer compositions

[0002] The invention relates to photopolymer compositions using selected triarylalkyl borate salts as coinitiators, a photopolymer composition with a selected oxidation potential, and holographic media and holograms produced therefrom, furthermore 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 likewise specific triarylalkyl borate salts suitable as coinitiators. Furthermore, a process for calculating the oxidation potential of the specific coinitiators against the saturated calomel electrode in acetonitrile is presented.Furthermore, a process for producing the special coinitiators as well as the coinitiators obtainable by this process are described.

[0003] Photopolymer compositions containing general forms of triarylalkyl borate salts are known in the art. For example, WO 2008 / 125229 describes a photopolymer composition and a photopolymer obtainable therefrom, which comprise polyurethane matrix polymers, an acrylate-based writing monomer, and photoinitiators containing a coinitiator and a dye. When using photopolymers, the refractive index modulation Δn generated by holographic exposure plays a crucial role. During holographic exposure, the interference field consisting of the signal and reference light beams (in the simplest case, that of two plane waves) is imaged into a refractive index grating by the local photopolymerization of writing monomers such as high-index acrylates at locations of high intensity in the interference field. The refractive index grating in the photopolymer (the hologram) contains all the information of the signal light beam.By illuminating the hologram with only the reference light beam, the signal can 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 Δn and the highest possible 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, it is particularly important for the large-scale use of holographic media made from photopolymer compositions 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 visible or near-infrared light. The preparation of such PIS is widely described in the prior art, and selected tetraalkylammonium triarylalkylborates and dyes for the near-infrared (NIR) range are commercially available. Furthermore, such PIS have already been used in photopolymers and holographic media, and their advantages have been described. For example, EP 0438123 describes cationic NIR dyes, such as the NIR dye of formula (1). which, together with the triphenylbutylborate anion, can be used to form a PIS for photocurable materials. This application also demonstrates the tri(p-anisyl)butylborate anion or the tri(l-naphthyl)butylborate anion as suitable coinitiators for PIS with cationic NIR dyes. Furthermore, it is known from US 6,022,664, which describes the preparation of thermally activatable photopolymers, that recording materials containing a PIS consisting of an NIR dye of formula (1) and certain triarylalkylborate salts cure almost completely after 5 seconds at a temperature of 120°C. However, in all these PIS, such as those described in EP 0438123, dye-coinitiator combinations and photopolymer compositions comprising a NIR dye and triarylalkyl borate salts, no attention was paid to the thermal stability of the formulation in the unexposed state.In fact, all the formulations disclosed in EP 0438123 do not exhibit sufficient thermal stability in the unexposed state. This means that under certain thermal stresses, such as 10 minutes of storage at 110 °C, which may be necessary to produce 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 without adversely affecting their bleachability or sensitivity during the exposure process. Furthermore, it was an object 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 the dye has a structure according to formula (II) wherein

[0011] R 205 represents hydrogen, halogen, C1- to C4-alkyl, C1- to C4-alkoxy or NR 210 R 211 stands,

[0012] R 206 represents hydrogen, halogen, C1- to C4-alkyl, C1- to C4-alkoxy or NR 212 R 213 stands,

[0013] R 201 to R 204 and R 210 to R 213each independently represents hydrogen, C1 to C 16 - Alkyl, C4- to C7-cycloalkyl, C7- to C 16 -Aralkyl, C6- to C 10 -aryl or a heterocyclic residue,

[0014] NR 201 R 202 , NR 203 R 204 , NR 210 R 211 and NR 212 R 213 independently of one another represent a five- or six-membered saturated ring attached via N, which may additionally contain an N or O and / or may be substituted by non-ionic radicals,

[0015] R 207 to R 209 independently of each other for hydrogen, C1 to C 16 -Alkyl, C4- to C7-cycloalkyl, C7- to C 16 -Aralkyl, C6- to C 10 -aryl, halogen or cyano, the two optional bridging groups X 1 and X 2 independently for SiR 214 R 215 , CR 216 R 217 or O and

[0016] R 214 to R 217 independently of one another represent hydrogen or C1- to C4-alkyl and

[0017] 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 t, 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 triarylalkylborate 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 1.01 V to 1.31 V against the saturated calomel (1) electrode (SCE) in acetonitrile

[0018] The matrix polymer a) can be any matrix polymer a) that a person skilled in the art would select for the photopolymer composition according to the invention. Suitable matrix polymers a) of the photopolymer composition can, in particular, be crosslinked and, more preferably, three-dimensionally crosslinked.

[0019] 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).

[0020] 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.

[0021] All compounds well known to the skilled person, or mixtures thereof, can be used as monomeric di- and triisocyanates. These compounds can have aromatic, araliphatic, aliphatic, or cycloaliphatic structures. In minor amounts, the monomeric di- and triisocyanates can also include monoisocyanates, i.e., organic compounds containing an NCO group.

[0022] 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 of 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 (ND1), 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.

[0023] 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.

[0024] The polyisocyanates are particularly preferably oligomerized aliphatic and / or cycloaliphatic di- or triisocyanates, and in particular the above-mentioned aliphatic and / or cycloaliphatic di- or triisocyanates can be used.

[0025] Polyisocyanates with isocyanurate, uretdione and / or iminooxadiazinedione structures as well as biurets based on HD1 or mixtures thereof are very particularly preferred.

[0026] 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 alll).

[0027] 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 most preferably as isocyanate-reactive compounds alll).

[0028] 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.

[0029] Examples of suitable alcohols are all polyhydric alcohols such as the C2- C 12 -diols, the isomeric cyclohexanediols, glycerol or any mixtures thereof.

[0030] Suitable polycarbonate polyols are obtainable in a conventional manner by reacting organic carbonates or phosgene with diols or diol mixtures. Suitable organic carbonates are dimethyl, diethyl, and diphenyl carbonate.

[0031] 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.

[0032] Suitable polyether polyols are optionally block-structured polyaddition products of cyclic ethers to OH- or NH-functional starter molecules.

[0033] Suitable cyclic ethers are, for example, styrene oxides, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin and any mixtures thereof.

[0034] Polyhydric alcohols with an OH functionality ≥ 2, as well as primary or secondary amines and amino alcohols, can be used as starters, as described in the context of polyester polyols.

[0035] 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 include all respective linear and branched C3 and C4 isomers.

[0036] 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.

[0037] These can, for example, in addition to the above-mentioned compounds, include neopentyl glycol,

[0038] 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-

[0039] 3-hydroxypropyl ester. Examples of suitable triols are trimethylolethane, trimethylolpropane, or glycerin. Suitable higher-functionality alcohols are di-(trimethylolpropane), pentaerythritol, dipentaerythritol, or sorbitol.

[0040] 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. 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.

[0041] 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.

[0042] All of the above-mentioned isocyanate-reactive compounds (alll) can be mixed with each other as desired.

[0043] 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.

[0044] 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.%.

[0045] 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, s-caprolactam, or mixtures thereof.

[0046] 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.

[0047] 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.

[0048] Suitable polyfunctional, isocyanate-reactive compounds of component all) are, for example, the compounds allI) described above. In a further preferred embodiment, the substance catalyzing the polyurethane formation originates from the group of Zn-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.

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

[0050] Suitable acrylate writing monomers are in particular compounds of the general formula (IV) where m≥l and m≤4 and R 5 a linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted with heteroatoms organic radical and / or R 6Hydrogen, a linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted with heteroatoms organic radical. R is particularly preferably 6 Hydrogen or methyl and / or R 5 a linear, branched, cyclic or heterocyclic unsubstituted or optionally substituted by heteroatoms organic radical.

[0051] In this context, acrylates and methacrylates are referred to as esters of acrylic acid and methacrylic acid, respectively. Examples of preferably usable 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.

[0052] 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.

[0053] 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 and the isomeric methylthiophenyl isocyanates. Di-, tri-, or polyisocyanates are 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.

[0054] 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, glycerin, pentaerythritol, dipentaerythritol, or technical mixtures thereof. 2-Hydroxyethyl acrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and poly(ε-caprolactone) mono(meth)acrylate are preferred.

[0055] 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.

[0056] 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.

[0057] It is also possible that the writing monomer b) comprises or consists 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.

[0058] 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 1) and bimolecular (type II) photoinitiators. Furthermore, depending on their chemical nature, they are classified as photoinitiators for radical, anionic, cationic, or mixed polymerization.

[0059] Type I photoinitiators (Norrish type 1) for radical photopolymerization form free radicals upon irradiation through unimolecular bond cleavage. Examples of type 1 photoinitiators are triazines, oximes, benzoin ethers, benzil ketals, bisimidazoles, aroylphosphine oxides, sulfonium, and iodonium salts.

[0060] 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.

[0061] Type II photoinitiators are preferred.

[0062] Such photoinitiator systems are described in principle in EP 0 223 587 A and preferably consist of a mixture of one or more dyes.

[0063] Suitable NIR chromophores which together with a compound of formula (III) form a type II photoinitiator are, for example, the cationic dyes described in EP 0438123.

[0064] Furthermore, pentamethine cyanine and heptamethine cyanine dyes, hemicyanine dyes, merocyanine dyes, oxonols, and neutrocyanine dyes are understood and preferred as cationic NIR dyes. Such dyes are described, for example, in H. Bemeth in Ullmann's Encyclopedia of Industrial Chemistry, Azine Dyes, Wiley-VCH Verlag, 2008; H. Bemeth in Ullmann's Encyclopedia of Industrial Chemistry, Methine Dyes and Pigments, Wiley-VCH Verlag, 2008; and T. Gessner and U. Mayer in Ullmann's Encyclopedia of Industrial Chemistry, Triarylmethane and Diarylmethane Dyes, Wiley-VCH Verlag, 2000.

[0065] Pentamethine cyanine and heptamethine cyanine dyes are particularly preferred.

[0066] Particularly preferred for a cationic NIR dye is the dye “Karenz IR-T” available from Showa Denko with the following structural formula (V):

[0067] Preferred anions (An- ) of the cationic NIR 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 -Per-fluoroalkanesulfonate, 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 C 12 - 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 C 18 -alkanecarboxylic acid esters, (sulfo-C2- to C6-alkyl)-acrylic or methacrylic acid esters, optionally substituted by up to 12 halogen radicals, triscatecholine 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- dicarbanidoundecaborate(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, dodecahydrodicarbadodecaborate(2-) or B-C1- to C 12 -Alkyl-C-phenyl-dodecahydrodicarbadodecaborate(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.

[0068] The anions described in WO 2012062655 are preferably used as anions.

[0069] 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.

[0070] Suitable coinitiators for a Type II photoinitiator system are anionic borates, particularly anionic triarylalkyl borates, which are described in WO 2015 / 055576. Other coinitiators can be pentacoordinated silicates or tertiary aromatic amines.

[0071] In a preferred embodiment of the photopolymer composition, the at least one dye has the structure of formula (11), wherein

[0072] R 205 represents hydrogen, C1- to C4-alkyl, or NR 210 R 211 stands,

[0073] R 206 represents hydrogen, C1- to C4-alkyl, or NR212 R 213 stands,

[0074] R 201 to R 204 and R 210 to R 213 each independently represents hydrogen, methyl, ethyl, propyl, butyl, chloroethyl, cyanomethyl, cyanoethyl, methoxyethyl, cyclopentyl, cyclohexyl, cyclohexylmethyl, benzyl, phenyl, tolyl, anisyl or chlorophenyl or

[0075] NR 201 R 202 , NR 203 R 204 , NR 210 R 211 and NR 212 R 213 independently of each other represent pyrrolidino, piperidino, morpholino or N-methylpiperazino,

[0076] R 207 to R 209 represent hydrogen and the two optional bridging groups X 1 and X 2 independently represent SiMe2 or O.

[0077] In a preferred embodiment of the photopolymer composition, the at least one dye has a structure of formula (XVX): where R 201to R 204 and R 210 to R 213 independently of one another each represent hydrogen or methyl, ethyl propyl or butyl. In a preferred embodiment of the photopolymer composition, the at least one dye present according to formula (1) or formula (XVX) has an organically substituted sulfonate as anion (An-).

[0078] In a preferred embodiment of the photopolymer composition, the at least one coinitiator is a triarylalkylborate salt.

[0079] In a preferred embodiment of the photopolymer composition, the coinitiator contains a triarylalkyl borate according to formula (III), which has a calculated oxidation potential between 1.01 V vs. SCE and 1.31 V vs. SCE in acetonitrile and wherein

[0080] A represents a methylene group or any substituted methine group which may optionally be substituted with R 10can form a ring with up to 10 members,

[0081] R 100 represents hydrogen or a C1 to C6 optionally substituted by hydroxy and / or alkoxy and / or acyloxy and / or halogen 20 -alkyl-, C3- to C 20 -Alkenyl-, C3- to C 20 -Alkynyl-, C5- to C7-cycloalkyl- or C7- to C 13 -aralkyl radical,

[0082] R 101 , R 102 , and R 103 for up to five independently selected residues from C1 to C 20 -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 C 12 -Alkoxy-, trifluoromethoxy-, trichloromethoxy-, C1- to C 12-Alkylthioyl-, thioyl-, difluoromethoxy-, difluoromethylthioyl-, carboxyl-, carbonyl-, 2-, 3-, or 4-pyridyl-, or arbitrarily substituted aryl residues or hydrogen, whereby the selection of the residues is determined by the fact that the calculated oxidation potential of the triarylalkylborate (111), which depends on the residues, lies in a range between 1.01 V vs. SCE and 1.31 V vs. SCE in acetonitrile,

[0083] 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. In this embodiment of the photopolymer composition, A preferably represents a methylene group.

[0084] In a preferred embodiment of the photopolymer composition, the triarylalkyl borate of structure (III) R 100 for a C1 to C 20 -alkyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical and R 101 , R102 , and R 103 represent 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 103 no hydrogen. In the case of two radicals R 101 , two R 102 , and two R 103 The two radicals are each arranged in the meta-position and para-position to the B atom on the aromatic compound. In this embodiment, A preferably represents a methylene group.

[0085] Furthermore, the triarylalkylborate of the structure (11) is preferably 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 103represents 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 independently of one another for selected halogen substituents, whereby halogen substituents include, in addition to halogen radicals such as Cl radical or F radical, also trihaloalkyl radicals, in particular trihalomethyl radicals and trihaloethyl radicals, in particular trifluoromethyl radicals and trichloromethyl radicals.

[0086] In a further preferred embodiment of the photopolymer composition, the triarylalkyl borate of the structure (11) R 100 for a C3 to C 12 -alkyl radical, 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 102and / or R 103 represents a halogen substituent. In the case of two radicals R 101 , two R 102 , and two R 103 the two radicals are each in the meta-position and para-position to the B atom. In this embodiment, A preferably represents a methylene group.

[0087] Furthermore, the triarylalkylborate of the structure (11) is preferably 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 represents a halogen substituent. The triarylalkyl borates shown below are particularly preferred, where K + each is any organocation based on nitrogen, phosphorus, oxygen, sulfur or iodine: 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

[0088] In a preferred embodiment of the photopolymer composition, the at least one coinitiator, in particular in combination with one of the previously described cationic dyes, has an oxidation potential calculated according to formula (1) in acetonitrile against the saturated calomel electrode in a range between 1.01 V vs. SCE and 1.20 V vs. SCE in acetonitrile, preferably between 1.01 V vs. SCE and 1.17 V vs. SCE and particularly preferably between 1.01 V vs. SCE and 1.15 V vs. SCE. Furthermore, 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 optionally carry further functional groups such as ethers, esters, amides and / or carbamates in one or more side chains and which can also be present in oligomeric, polymeric or bridging form. K is preferably + 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.

[0089] Further preferred are K + an organocation of valence n based on oxygen, such as an arbitrarily substituted pyrylium cation, which can also be present in fused form such as benzopyrylium, flavylium, naphthoxanthenium cation, or a polymeric cation with the substitution patterns mentioned.

[0090] More preferably, K + 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 - can carry 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.

[0091] 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 substitution patterns mentioned.

[0092] The photoinitiator system may also contain another coinitiator c111) such as trichloromethyl initiators, iodonium salts, sulfonium salts, aryloxide initiators, bisimidazole initiators, ferrocene initiators, oxime initiators, thiol initiators or peroxide initiators.

[0093] 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 blue, green, red, and NIR. Finally, it is very particularly preferred if the photopolymer composition contains a suitable photoinitiator for each of the laser light colors.

[0094] 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), where the urethanes may, in particular, be substituted by at least one fluorine atom.

[0095] Preferably, the urethanes can have the general formula (XVIII) where o ≥ 1 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, organic radical.

[0096] Preferred is 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 (XVIII).

[0097] The statements made above regarding the photopolymer composition according to the invention with regard to further preferred embodiments also apply analogously to the photopolymer according to the invention.

[0098] A further subject of the present invention relates to a layer structure comprising at least the layers:

[0099] A. a substrate layer A, which may be part of a further layer structure,

[0100] B. a photopolymer layer B, formed from the photopolymer composition according to the invention, and

[0101] C. a cover layer C, which may be part of the further layer structure.

[0102] A further subject matter of the present invention relates to a layer structure comprising at least the following layers: A. a substrate layer A, which is optionally part of a further layer structure, B'. an exposed or cured photopolymer layer B', which was produced from the photopolymer composition according to the invention by curing by means of light, and

[0103] C. a cover layer C, which may be part of the further layer structure.

[0104] 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, and 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. Particular preference is given to PC / PET, PET / PC / PET, and PC / TPU (TPU = thermoplastic polyurethane). 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.

[0105] In addition, a further method for producing a holographic medium using a photopolymer composition according to the invention is disclosed, which likewise yields holographic media in the form of films. In this case, 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 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. Particular preference is given to PC / PET, PET / PC / PET, and PC / TPU (TPU = thermoplastic polyurethane).The materials or material composites of the carrier can be made 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 removed from the carrier A without 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, which are required, for example, for processing in roll laminators, particularly in roll-to-roll processes.

[0106] Also disclosed are material composites of the type described above, comprising a photoexposed, 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 / B7C.

[0107] Holographic information can be imprinted into such holographic media.

[0108] The invention further relates to a holographic medium comprising a photopolymer composition according to the invention. Holographic media can be processed into holograms by appropriate exposure processes for optical applications in the red and NIR range (600-1200 nm). Visual holograms and holograms that operate in the NIR range include all holograms that can be recorded by 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, or transmission holograms are preferred.

[0109] A further 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).

[0110] 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, light guides, waveguides, projection screens, and / or masks. Combinations of these optical functions can also be combined independently of one another in a hologram (multiplexing). These optical elements often exhibit frequency selectivity, depending on how the holograms were exposed and the dimensions of the hologram.

[0111] The above-described functions of the holograms that can be produced with the photopolymer compositions according to the invention are used, for example, but not exclusively, in the areas of eye tracking, sensing, as well as LID AR and augmented reality, head-mounted display and virtual reality applications in the NIR range.

[0112] A further subject matter of the invention relates to an optical display comprising a holographic medium according to the invention.

[0113] 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.

[0114] A further subject matter of the invention relates to the use of a holographic medium according to the invention for producing chip cards, identification 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, LID AR, augmented reality, head-mounted display and virtual reality applications, in particular in the near infrared range and a combination of at least two thereof. The holographic media can be used for recording 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 producing optical elements, images or image representations.

[0115] Holograms are accessible from holographic media according to the invention by appropriate exposure.

[0116] Examples and character descriptions:

[0117] The following examples serve to illustrate the invention without limiting it to them.

[0118] Measurement of the OH number and the NCO value:

[0119] OH number: The stated OH numbers were determined according to DIN 53240-2.

[0120] NCO value: The specified NCO values ​​(isocyanate contents) were determined according to DIN EN ISO

[0121] 11909 determined.

[0122] Measurement of the holographic properties DE and Δn of the holographic media / photopolymer films using two-beam interference in reflection arrangement:

[0123] The beam of an NIR laser (emission wavelength 850 nm) was converted into a parallel, homogeneous beam using the spatial filter (SF) and the 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 1.75 mW and the power of the signal beam to 2.25 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 -21.8°, and the angle of incidence (β0) of the signal beam is 41.8°. The angles are measured from the sample normal to the beam direction. According to Scheme 1, α0 has a negative sign and β0 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 ~296 nm (assuming the refractive index of the medium to be ~1.51).

[0124] 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 = 850 nm (NIR laser) (M = mirror, S = shutter, SF = spatial filter, CL = collimator lens, λ / 2 = λ / 2 plate, PBS = polarization-sensitive beam splitter, D = detector, I = iris diaphragm, α0 = -21.8°, β0 = 41.8° are the angles of incidence of the coherent beams measured outside the sample (the medium), RD = reference direction of the turntable) is shown.

[0125] Holograms were written into the medium in the following way:

[0126] • Both shutters (S) are open for the exposure time t.

[0127] • Afterwards, with the shutters closed (S), the medium was allowed 5 minutes for the diffusion of the not yet polymerized writing monomers.

[0128] The written holograms were then read out as follows: The shutter of the signal beam remained closed. The shutter of the reference beam was open. The iris of the reference beam was closed to a diameter of < 1 mm. This ensured that for all rotation angles (Ω) of the medium, the beam always lay completely within the previously written hologram. The turntable then covered the angular range of Ω under computer control. min to Ω 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 = - 31.8° and β0 = 31.8°. Then Ω is recording = 0°. For α0= -21.8° and β0= 41.8°, Ω recording hence 10°. In general, the interference field during recording of the hologram is: α0= θ0+ Ω recording . (3) θ0 is the half-angle in the laboratory system outside the medium and the following applies when writing the hologram:

[0129] In this case, θ0 = -31.8°. 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:

[0130] 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.

[0131] Using the method described above, the Bragg curve of the written hologram, which describes the diffraction efficiency η as a function of the rotation angle Ω, was measured and stored in a computer. In addition, the intensity transmitted in the zeroth order was plotted against the rotation angle Ω and stored in a computer. The maximum diffraction efficiency (DE = η max) of the hologram, i.e. its peak value, was measured at Ω reconstruction The position of the detector of the diffracted beam may have had to be changed to determine this maximum value.

[0132] 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) can deviate from the fringe spacing A of the interference pattern and its orientation. Accordingly, the angle α0' or the corresponding angle of the rotary table Ω reconstruction, at which maximum diffraction efficiency is achieved from α0 or from the corresponding Ω recording This changes the Bragg condition. This change is taken into account in the evaluation procedure. The evaluation procedure is described below:

[0133] All geometric quantities that refer to the written hologram and not to the interference pattern are represented as primed quantities.

[0134] According to Kogelnik, the Bragg curve η (Ω) of a reflection hologram is:

[0135] When reading the hologram (“reconstruction”), the following applies as shown above:

[0136] At the Bragg condition, the dephasing is DP = 0. And it follows accordingly: α '0= θ0+ Ω r ec on s t ruction

[0137] (16) sin(α '0) = n • sin(α ') (17)

[0138] The still unknown angle β' can be determined by comparing the Bragg condition of the interference field during writing the hologram and the Bragg condition during reading the hologram, assuming that only thickness shrinkage occurs. Then we get: v is the grid strength, ξ is the detuning parameter and the orientation (slant) of the refractive index grating that was written; α ' and β' correspond to the angles α0 and β0 of the interference field during writing of the hologram, but measured in the medium and valid for the hologram grating (after thickness shrinkage); n is the average refractive index of the photopolymer and was set to 1.51. λ is the wavelength of the laser light in vacuum.

[0139] The maximum diffraction efficiency (DE = η max ) then results for ξ = 0:

[0140] 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 '0-ϑ'0, also called angle detuning. Figure 2 shows the measured transmitted power P T (right y-axis) is plotted as a solid line (here of example 3a) against the angle detuning ΔΩ, the measured diffraction efficiency η (left y-axis) is plotted as filled circles against the angle detuning ΔΩ (as far as the finite size of the detector allowed) and the fit of the Kogelnik theory is plotted as a dashed line (left y-axis).

[0141] Since DE is known, the shape of the theoretical Bragg curve according to Kogelnik is determined solely by the thickness d' of the photopolymer layer. Δn is corrected via DE for a given thickness d' such that the measurement and theory of DE always agree. d' is then adjusted until the angular positions of the first secondary minima of the theoretical Bragg curve agree with the angular positions of the first secondary maxima of the transmitted intensity, and the full width at half height (FWHM) for the theoretical Bragg curve and the transmitted intensity agree.

[0142] Since the direction in which a reflection hologram rotates during reconstruction using an Ω-scan is limited, and the detector for the diffracted light can only capture a finite angular range, the Bragg curve of wide holograms (small d') is not completely captured in an Ω-scan, but only the central region, with appropriate detector positioning. Therefore, the shape of the transmitted intensity complementary to the Bragg curve is also used to adjust the layer thickness d'.

[0143] 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.

[0144] 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 = 1.75 mW and signal beam with P s = 2.25 mW), the exposure time t and the diameter of the iris diaphragm (0.4 cm):

[0145] 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.

[0146] Calculation of the oxidation potential of triarylalkyl borates:

[0147] The absolute oxidation potential ), referenced against the saturated calomel electrode, was calculated using the following formula (2):

[0148] Where n e the number of transferred electrons (here always n e = 1), F is the Faraday constant the absolute potential value of the standard hydrogen electrode (SHE) the potential of the saturated calomel electrode (SCE) relative to the SHE in Acetonitrile and G 298 and G 298 (oxidized) the calculated Gibbs energies at 298 K of the ground state and the oxidized state of the triarylalkylborate.

[0149] Formula (2) can also be expressed as follows after inserting the above-mentioned constants (formula (1)):

[0150] The Gibbs energies at 298 K of the ground state and the oxidized state were calculated as follows: First, the three-dimensional molecular geometry of the triarylalkyl borate was generated using ChemDraw 3D and subjected to conformer analysis. The conformers found were energetically minimized using the AMI force field, and the resulting 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 ( G 298 (oxidized)).

[0151] Substances:

[0152] 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.

[0153] Polyol 1 was prepared as described in WO2015091427 with an OH-

[0154] Number of 56.8.

[0155] Desmodur® N 3900 Product of Covestro AG, Leverkusen, DE, hexane diisocyanate-based polyisocyanate, iminooxadiazinedione content at least 30%, NCO content: 23.5%.

[0156] Iron(III) trifluoroacetylacetonate [14526-22-8] is available from ABCR GmbH & Co. KG, Karlsruhe, Germany.

[0157] Urethane acrylate 1 (phosphorothioyltris(oxybenzene-4,1-diylcarbamoyloxyethane-2,1-diyl)trisacrylate, [1072454-85-3]) was prepared as described in WO2015091427. Urethane acrylate 2 (2-({[3-(methylsulfanyl)phenyl]carbamoyl}oxy)-ethylprop-2-enoate, [1207339-61-4]) was prepared as described in WO2015091427.

[0158] 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.

[0159] Karenz™ 1R-T supplied by Showa Denko EUROPE GmbH, [96233-24-8].

[0160] Karenz™ P3B supplied by Showa Denko EUROPE GmbH, [120307-06-4].

[0161] Cation 2 N1, N 22 -Di hexadecyl- N1, N1, N 22 , N 22 , 10,10, 13-heptamethyl-7, 16-di- oxo-3, 6, 17,20-tetraoxa-8, 15-diazadocosane-1 ,22-diaminium dibromide was prepared as described in WO 2018087064.

[0162] BYK-310 Silicone-containing surface additive, product of BYK-Chemie

[0163] GmbH, Wesel, Germany.

[0164] Synthesis instructions:

[0165] Preparation of N-ethyl-N-[4-[(1,5,5-tris[4-(diethylamino)phenyl]-2,4-pentadienylidene]-2,5-cyclohexadien-1-ylidene]ethanaminium bis(2-ethylhexyl)sulfosuccinate (Dye 1): 4.08 g of sodium bis(2-ethylhexyl)sulfosuccinate (1.0 eq.) were dissolved in 80 mL of deionized water. 7.44 g of Karenz 1R-T (1.0 eq.) in 100 mL of butyl acetate were added to this solution, and the two-phase mixture was stirred at RT for 3 h. The aqueous phase was then separated, and the organic phase was washed five times with 80 mL of deionized water each time. Finally, the solvent was removed under vacuum using a rotary evaporator and the product was obtained as a dark blue resin (9.50 g, 98% of theory).

[0166] Preparation of N, N-dimethyl- N-(3-phenylpropy l)-hexadecylammonium chloride (cation 1):

[0167] 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 were 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.

[0168] Preparation instructions for tetrabutylammonium triarylalkyl borates with R 101 =R 102 =R 103 :

[0169] In a four-necked flask equipped with a thermometer, reflux condenser, dropping funnel, and magnetic stirrer, the corresponding diisopropylalkylborate (1.0 eq.) and magnesium turnings (3 eq.) are placed in a solvent mixture consisting of dry toluene and dry THF (5.8:1, 1.9 M). This mixture is stirred for 30 min at room temperature. The corresponding bromoaromatic compound (3 eq.) is then added dropwise to the mixture, initially undiluted, until the onset of exothermic reaction signals the start of the reaction. However, a maximum of 10% of the undiluted bromoaromatic compound is used for this purpose. The remainder of the bromoaromatic compound is 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) such that the reaction temperature does not exceed 45 °C. After the addition is complete, the reaction solution is heated under reflux until the magnesium is completely dissolved or for 1 h.The reaction solution is cooled to room temperature and poured into a mixture of ice water and tetrabutylammonium bromide (1 eq.). The mixture is stirred for 1 h, and then the organic phase is separated. The organic phase is washed with water until a halide test (HNO3 (aq., 10%) + AgNO3) is negative. The solvents are removed in vacuo using a rotary evaporator, and the crude product is recrystallized from methanol.

[0170] Preparation instructions for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 103 :

[0171] In a four-necked flask equipped with a thermometer, reflux condenser, dropping funnel, and magnetic stirrer, the corresponding diisopropylalkylborate (1.0 eq.) and magnesium turnings (3 eq.) are placed in a solvent mixture consisting of dry toluene and dry THF (4:1, 1.9 M). This mixture is stirred for 30 min at room temperature. The first bromoaromatic compound (1 eq.) is then added dropwise undiluted to the mixture until an exothermic reaction signals the start of the reaction. However, a maximum of 10% of the undiluted bromoaromatic compound is used for this purpose. The remainder of the bromoaromatic compound is added dropwise to the reaction solution in a solvent mixture consisting of dry toluene and dry THF (1.1:1, diluting the total molarity to 0.7 M) such that the reaction temperature does not exceed 45 °C. After complete addition, the reaction solution is stirred at RT for 1 h.The corresponding second aromatic bromide is then added dropwise to the mixture, initially undiluted, until the onset of an exothermic reaction signals the start of the reaction. However, a maximum of 10% of the undiluted aromatic bromide is used for this purpose. The remainder of the aromatic bromide is 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 does not exceed 45 °C. After the addition is complete, the reaction solution is heated under reflux until the magnesium has completely dissolved or for 1 h. The reaction solution is cooled to room temperature and poured onto a mixture consisting of ice water and tetrabutylammonium bromide (1 eq.). The mixture is stirred for 1 h, and the organic phase is separated. The organic phase is washed with water until a halide test (HNO3 (aq., 10%) + AgNO3) is negative.The solvents are removed in vacuo using a rotary evaporator and the crude product is recrystallized from methanol.

[0172] Preparation instructions for triarylalkyl borates with cations of valence n=1:

[0173] The corresponding tetrabutylammonium triarylalkylborate (1 eq.) is 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 is stirred at RT for 1 h. After phase separation, the organic phase is washed frequently with water until a halide test (HNO3(aq., 10%) + AgNO3) is negative. The solvent is removed in vacuo using a rotary evaporator, and the product is dried under vacuum.

[0174] Preparation procedure for triarylalkyl borates with cations of valence n=2:

[0175] The corresponding tetrabutylammonium triarylalkylborate (1 eq.) is 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 stirred at RT for 1 h. After phase separation, the organic phase is washed frequently with water until a halide test (HNO3(aq., 10%) + AgNO3) is negative. The solvent is removed in vacuo using a rotary evaporator, and the product is dried under vacuum.

[0176] Manufacturing instructions for photopolymer film / holographic media:

[0177] 14.9 g of the polyol component 1 described above are melted and mixed in the dark with 6.6 g of the urethane acylate 1, 6.6 g of the urethane acrylate 2 described above, 9.2 g of the fluorinated urethane (additive 1) described above, 0.45 g of the respective borate salt described above, 0.10 g of the coloring agent 1, 0.12 g of BYK-310, 0.01 g of iron(III) trifluoroacetylacetonate, 10.5 g of ethyl acetate, 1.1 g of butyl acetate, and 7.7 g of 1-methoxy-2-propyl acetate, to obtain a homogeneous solution. Then, 2.8 g of Desmodur® N 3900 are added and mixed again. This solution is applied to a 60 μm thick TAC film in a roll-to-roll coating system in the dark and spread using a doctor blade to achieve a wet film thickness range of 14-17 μm. The coated film is dried at a drying temperature of 80 °C and a drying time of approximately 4 minutes and then protected with a 40 μm thick polyethylene film.This film is then packaged in a light-tight manner.

[0178] Preparation of N-benzyl- N, N-dimethylhexadecylammonium di-(3-chloro-4-methylphenyl)-(4-methylphenylhexylborate): According to the general preparation procedure for tetrabutylammonium triarylalkylborates with R 101 =R 102 ≠R 103 3-chloro-4-methylbromobenzene (2 eq.) and 4-methylbromobenzene (1 eq.) were reacted with diisopropylhexylborate. Following the general preparation procedure for triarylhexylborates with cations of valence n=1, the resulting tetrabutylammonium triarylhexylborate was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (18.92 g, 42% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.6 ppm. The calculated reduction potential was E ox = 1.02 V vs. SCE in acetonitrile.

[0179] Preparation of a photopolymer with N-benzyl-N, N-dimethyl hexadecylammonium di-(3-chloro- 4-methylphenyl)(4-methylphenyl)hexylborate (Example 3a in Table 2):

[0180] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared with N-benzyl-N,N-dimethylhexadecylammonium di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate as coinitiator.

[0181] Preparation of N-(3-phenylpropyl)-N,N-dimethylhexadecylammonium di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate:

[0182] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 1033-chloro-4-methylbromobenzene (2 eq.) and 4-methylbromobenzene (1 eq.) were 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 (2.5 g, 42% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.6 ppm. The calculated reduction potential was E ox = 1.02 V vs. SCE in acetonitrile.

[0183] Preparation of a photopolymer with N-(3-phenylpropyl)-N,N-dimethylhexadecylammonium di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate (Example 3b in Table 2):

[0184] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-(3-phenylpropyl)-N,N-dimethylhexadecylammonium di-(3-chloro-4-methyl-phenyl)(4-methylphenyl)hexylborate as coinitiator.

[0185] Preparation of tributyltetradecylphosphonium di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate:

[0186] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 103 3-chloro-4-methylbromobenzene (2 eq.) and 4-methylbromobenzene (1 eq.) were reacted with diisopropylhexylborate. The general preparation procedure for triarylalkyl borates with cations of valence n=1 was then followed using tributyltetradecylphosphonium bromide. A colorless oil (1.2 g, 42% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.6 ppm. The calculated reduction potential was E ox = 1.02 V vs. SCE in acetonitrile.

[0187] Preparation of a photopolymer with tributyltetradecylphosphonium di-(3-chloro-4-methyl-phenyl)(4-methylphenyl)hexylborate (Example 3c in Table 2):

[0188] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using tributyltetradecylphosphonium di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate as coinitiator.

[0189] Production of N1,N 22 -Dihexadecyl- N1,N1,N 22 ,N 22 ,10,10,13-heptamethyl-7,16-dioxo-3,6,17,20-tet-raoxa-8,15-diazadocosan-l,22-diaminium-bis-di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate:

[0190] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 103 3-chloro-4-methylbromobenzene (2 eq.) and 4-methylbromobenzene (1 eq.) were reacted with diisopropylhexylborate. The general preparation procedure for triarylalkyl borates with cations of valence n=1 was then followed using cation 2. A colorless oil (2.7 g, 42% of theory over two steps) with a signal in the 11B-NMR spectrum at δ (ppm) (CDCl3) = -10.6 ppm. The calculated reduction potential was E ox = 1.02 V vs. SCE in acetonitrile.

[0191] Preparation of a photopolymer with N1,N 22 -Dihexadecyl- N1, N1,N 22 ,N 2 2, 10, 10, 13- heptame thyl-7, l 6- dioxo-3,6, 17,20-tetraoxa-8, 15-diazadocosane-l ,22-diaminium bis-di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate (Example 3d in Table 2):

[0192] 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,l 5-diaz- adocosane-l,22-diaminium-bis-di-(3-chloro-4-methylphenyl)(4-methylphenyl)hexylborate as coinitiator.

[0193] Preparation of N-benzyl-N, N-dimethylhexacylammonium di-(4-chlorophenyl)(4-methylphenyl)hexylborate:

[0194] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 103 4-chlorobromobenzene (2 eq.) and 4-methylbromobenzene (1 eq.) were reacted with diisopropylhexylborate. Following the general preparation procedure for triarylhexylborates with cations of valence n=1, the resulting tetrabutylammonium triarylhexylborate was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (2.4 g, 60% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.7 ppm. The calculated reduction potential was E ox = 1.03 V vs. SCE in acetonitrile. Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium di-(4-chlorophenyl)(4-methylphenyl)hexylborate (Example 8 in Table 2):

[0195] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium di-(4-chlorophenyl)(4-methylphenyl)hexylborate as coinitiator.

[0196] Preparation of N-(3-phenylpropyl)-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)cyclohexylborate:

[0197] The preparation procedure published in WO2018 / 087064 for the preparation of tetrabutylammonium tri-(3-chloro-4-methylphenyl)cyclohexylborate was followed. Subsequently, the general preparation procedure for triarylalkyl borates with cations of valence n=1 was followed using cation 1. A slightly yellowish oil (5.0 g, 99% of theory) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -8.7 ppm. The calculated reduction potential was E ox = 1.03 V vs. SCE in acetonitrile.

[0198] Preparation of a photopolymer with N-(3-phenylpropyl)-N, N-dimethyl hexadecylammonium tri-(3-chloro-4-methylphenyl)cyclohexylborate (Example 11 in Table 2):

[0199] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-(3-phenylpropyl)-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenylcyclohexylborate) as coinitiator.

[0200] Preparation of N-benzyl-N,N-dimethylhexadecylammonium diphenyl-(3-chloro-4-methyl-phenyl)hexylborate:

[0201] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 103Bromobenzene (2 eq.) and 3-chloro-4-methylbromobenzene (1 eq.) were reacted with diisopropylhexylborate. The reaction product was obtained after silica gel column chromatography (dichloromethane / toluene 70:30). Subsequently, according to the general preparation procedure for triarylhexylborates with cations of valence n=1, the resulting tetrabutylammonium triarylhexylborate was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (0.68 g, 76% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.4 ppm. The calculated reduction potential was E ox = 1.04 V vs. SCE in acetonitrile.

[0202] Preparation of a photopolymer with N-benzyl-N,N-dimethyl hexadecylammonium diphenyl(l-(3-chloro-4-methylphenyl)hexylborate (Example 12 in Table 2): According to the general preparation procedure for photopolymer films, a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium diphenyl(3-chloro-4-methylphenyl)hexylborate as co-initiator was prepared.

[0203] Preparation of N-benzyl-N,N-dimethylhexadecylammonium diphenyl-(4-fluorophenyl)-hexylborate:

[0204] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 ≠R 103Bromobenzene (2 eq.) and 4-fluorobromobenzene (1 eq.) were reacted with diisopropylhexylborate. The reaction product was obtained after silica gel column chromatography (dichloromethane / toluene 70:30). Subsequently, according to the general preparation procedure for triarylalkylborates with cations of valence n=1, the resulting tetrabutylammonium triarylhexylborate was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (0.74 g, 34% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.5 ppm. The calculated reduction potential was E ox = 1.06 V vs. SCE in acetonitrile.

[0205] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium diphenyl-(4-fluorophenyl)hexylborate (Example 15 in Table 2):

[0206] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium diphenyl-(4-fluorophenyl)hexylborate as coinitiator.

[0207] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)-3-phenylpropylborate:

[0208] The preparation procedure published in WO2018 / 087064 was followed for the preparation of tetrabutylammonium tri-(3-chloro-4-methylphenyl)-3-phenylpropylborate. Subsequently, the resulting tetrabutylammonium triarylalkylborate was reacted with N-benzyl-N,N-dimethylhexadecyammonium chloride hydrate according to the general preparation procedure for triarylalkylborates with cations of valence n=1. A slightly yellowish oil (4.8 g, 99% of theory) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.3 ppm. The calculated reduction potential was E ox = 1.11 V vs. SCE in acetonitrile.

[0209] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)-3-phenylpropylborate (Example 38 in Table 2):

[0210] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)-3-phenylpropyl borate as coinitiator.

[0211] Preparation of tetrabutylammonium tri-(4-fluorophenyl)dodecylborate: The preparation procedure published in WO2018 / 087064 was followed for the preparation of tetrabutylammonium tri-(4-fluorophenyl)dodecylborate. A colorless oil (8.9 g, 12% of theory) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.4 ppm. The calculated reduction potential was E ox = 1.13 V vs. SCE in acetonitrile.

[0212] Preparation of a photopolymer with tetrabutylammonium tri-(4-fluorophenyl)dodecylborate (Example 41 in Table 2):

[0213] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using tetrabutylammonium tri-(4-fluorophenyl)dodecylborate as coinitiator.

[0214] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methyl-phenyl)hexyl borate:

[0215] The manufacturing procedure published in WO 2018 / 099698 was followed. The calculated reduction potential was E ox = 1.15 V vs. SCE in acetonitrile.

[0216] Preparation of a photopolymer with N-benzyl-N, N-dimethyl hexadecylammonium tri-(3-chloro-4-methylphenyl)hexylborate (Example 48 in Table 2):

[0217] 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.

[0218] Preparation of N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methyl-phenyl)butyl borate:

[0219] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 =R 103 3-chloro-4-methylbromobenzene 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 (2.4 g, 24% of theory over two steps) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.6 ppm. The calculated reduction potential was Eox = 1.15 V vs. SCE in acetonitrile.

[0220] Preparation of a photopolymer with N-benzyl-N, N-dimethyl hexadecylammonium tri-(3-chloro-4-methylphenyl)butylborate (Example 49 in Table 2):

[0221] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chloro-4-methylphenyl)-butylborate as coinitiator.

[0222] Preparation of tetrabutylammonium tri-(4-chlorophenyl)hexylborate: According to the general preparation procedure for tetrabutylammonium triarylalkylborates with R 101 =R 102 =R 103 4-chlorobromobenzene was reacted with diisopropylhexylborate. Colorless crystals (56 g, 50% of theory) with a signal in the 11 B-NMR spectrum at δ (ppm) (CDCl3) = -9.9 ppm. The calculated reduction potential was E ox = 1.17 V vs. SCE in acetonitrile.

[0223] Preparation of a photopolymer with tetrabutylammonium tri-(4-chlorophenyl)hexylborate (Example 56 in Table 2):

[0224] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using tetrabutylammonium tri-(4-chlorophenyl)hexylborate as coinitiator.

[0225] Preparation of N,N-dimethyl-N-(3-phenylpropyl)hexadecylammonium triphenylbutylborate:

[0226] Following the general preparation procedure for triarylalkyl borates with cations of valence n=1, tetrabutylammonium triphenylbutylborate (Karenz P3B) was reacted with N-benzyl-N,N-dimethylhexadecylammonium chloride hydrate to give N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium triphenylbutylborate. A colorless amorphous solid was obtained (54 g, >99% of theory) with a signal 11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.3 ppm. The calculated reduction potential was E ox = 1.00 V vs. SCE in acetonitrile..

[0227] Preparation of a photopolymer with N,N-dimethyl-N-(3-phenylpropyl)-hexadecyl-ammonium triphenylbutylborate (example NEB1 in Table 2):

[0228] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium triphenylbutylborate as coinitiator.

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

[0230] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates 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-N,N-dimethylhexadecylammonium chloride hydrate. A colorless oil (2.5 g, 50% of theory over two steps) with a signal in the11 B-NMR spectrum at δ (ppm) (CDCl3) = -10.1 ppm. The calculated reduction potential was E ox = 1.32 V vs. SCE in acetonitrile.

[0231] Preparation of a photopolymer with N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chlorophenyl)hexylborate (example NEB2 in Table 2):

[0232] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N-benzyl-N,N-dimethylhexadecylammonium tri-(3-chlorophenyl)hexylborate as a coinitiator. Preparation of N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium tri-(4-trifluoromethylphenyl)hexylborate:

[0233] According to the general manufacturing procedure for tetrabutylammonium triarylalkyl borates with R 101 =R 102 =R 1034-Bromobenzene trifluoride was reacted with diisopropylhexyl borate. 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.

[0234] Preparation of a photopolymer with N,N-dimethyl-N-(3-phenylpropyl)-hexadecyl-ammonium tri-(4-trifluoromethylphenyl)hexylborate (example NEB3 in Table 2):

[0235] According to the general manufacturing procedure for photopolymer films, a photopolymer was prepared using N,N-dimethyl-N-(3-phenylpropyl)-hexadecylammonium tri-(4-trifluoromethyl-phenyl)hexylborate as coinitiator.

[0236] Examples

[0237] 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 GAMESS software package (G. MJ. Barca, C. Bertoni, L. Carrington, D. Datta, N. De Silva, JE Deustua, DG Fedorov, JR Gour, AO Gunina, E. Guidez, T. Harville, 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, T. Sattasathuchana, MW Schmidt, J. Shen, L. Slipchenko, M. Sosonkina, V. Sundriyal, A. Tiwari, J.L. 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 following table.For the calculation of the oxidation potential, the cation of the corresponding trialkylarylborate is irrelevant, so the values ​​listed below apply to salts of the following general structure: (24), where K. + or K 2+ represent any ammonium or phosphonium cation.

[0238] Table 1. Oxidation potentials of various triarylalkylborate anions calculated according to formula (1), where the given radicals refer to the above general structure of formula (24) and the oxidation potential is given in V in comparison to the saturated calomel electrode in the solvent acetonitrile.

[0239] Table la.: Oxidation potentials of various triarylalkylborate anions calculated according to formula (III), wherein the radicals indicated refer to formula (III) from claim 6 and the oxidation potential is given in [V] in comparison to the saturated calomel electrode in the solvent acetonitrile.

[0240] Evaluation of the thermal stability of photopolymer films with coinitiators according to the invention:

[0241] The requirement for the photopolymer films produced here is a low loss of performance of the

[0242] Photoactivity after a tempering step, ie that both the transmission of the photopolymer must not increase critically after the tempering step and the diffraction efficiency must not decrease critically after hologram exposure.

[0243] 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 each tempered for 10 minutes at 110 °C in a drying cabinet. After the tempering step, a transmission spectrum (Tijemp) was also recorded for the sample. Using a laser setup as described above, a test hologram was inscribed into the photopolymer layer of both samples using an 850 nm laser. The quality of this hologram was evaluated based on the refractive index difference between exposed and unexposed areas (Δn) in the sample, derived from the readout diffraction efficiency. The thermostability of a NIR-light-sensitive photopolymer was evaluated based on two criteria that must be met. The two fulfillment criteria are therefore described in detail:

[0244] 1. Thermostability evaluated by transmission loss TS(T): The ratio of the transmission at the absorption maximum of the dye used (here 830 nm) after the tempering step of the temp sample T l,Temp,830 to the transmission of the RT sample at the same wavelength T l,RT,830 must be greater than 50%. The transmission values ​​must be corrected for background absorption caused by turbidity or similar (here the transmission at 1000 nm is used as a reference value) (T 2, Temp, 1000 ):

[0245] 2. Thermostability evaluated according to Δn: TS(Δn): The refractive index difference Δn of the temp sample must be greater than 0.015:

[0246] TS (Δn) = Δn Temp > 0.0150 (22)

[0247] The following transmission and Δn values ​​of some examples according to the invention and non-invention were determined:

[0248] Table 2. Measured transmittance and Δn values ​​of the inventive and non-inventive examples, as well as the calculated ratings. T l,RT,830 : Transmission of the RT sample at 830 nm; T l,Temp,830 - Transmission of the Temp sample at 830 nm, T 2, Temp, 1000 - Background transmission determined at 1000 nm; TS(T): evaluation of thermostability according to transmission loss; TS(Δn): evaluation of thermostability according to Δn.

[0249] * vs. SCE in acetonitrile; calculated; based on the triarylalkyl borate used.

[0250] The results clearly demonstrate that the required thermal stability of a photopolymer is achieved with the triarylalkyl borate salts according to the invention. Therefore, a photopolymer can only be considered sufficiently thermally stable if the calculated oxidation potential of the borate salt used is greater than 1.00 V and less than 1.32 V vs. SCE in acetonitrile.

[0251] The use of all borates listed in Table 1 as coinitiators in photopolymers therefore leads to thermostable photopolymers in accordance with the objective of this invention. It is also striking that the thermostability of the photopolymer does not depend on the countercation of the borate salt used, as a comparison of Examples 3a to 3d shows. A variation of the alkyl radical of the triarylalkyl borate salt is also possible without loss of the thermostability of the photopolymer, as Examples 11, 38, 48, and 49 demonstrate.

[0252] The non-inventive examples NEB1, NEB2 and NEB3 fail in at least one required property and are therefore unsuitable for providing a photopolymer composition with 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, characterized in that at least one of the dyes has a structure according to formula (11) wherein R 205 for hydrogen, halogen, C1- to C4-alkyl, C1- to C4-alkoxy or NR 210 R 211 stands, R 206 for hydrogen, halogen, C1- to C4-alkyl, C1- to C4-alkoxy or NR 212 R 213 stands, R 201 to R 204 and R 210 to R 213 each independently of each other for hydrogen, C1- to C 16- Alkyl, C4- to C7-cycloalkyl, C7- to C 16 -Aralkyl, C6- to C 10 -aryl or a heterocyclic residue, NR 201 R 202 , NR 203 R 204 , NR 210 R 211 and NR 212 R 213 independently of each other stand for a five- or six-membered saturated ring linked via N, which may additionally contain an N or O and / or be substituted by non-ionic residues, R 207 to R 209 independently of each other for hydrogen, C1 to C 16 -Alkyl, C4- to C7-cycloalkyl, C7- to C 16 -Aralkyl, C6- to C 10 -Aryl, halogen or cyano are the two optional bridging groups X 1 and X 2 independently for SiR 214 R 215 , CR 216 R 217 or stand in O and R 214 to R 217 independently of each other they stand for hydrogen or C1 to C4 alkyl and An for 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 which at least one coinitiator has a calculated oxidation potential, determine- The Gibbs energies at 298 K of the ground state and the oxidized state of the triaryl alkylborate are determined according to the formula (1) below by quantum mechanical calculation of the Gibbs energies 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 1.01 V to 1.31 V against the saturated calomel electrode (SCE) in acetonitrile.

2. The photopolymer composition according to one of the preceding claims, wherein the at least one dye has a structure of formula (11), wherein R 205 for hydrogen, C1 to C4 alkyl, or NR 210 R 211 stands, R 206 for hydrogen, C1 to C4 alkyl, or NR 212 R 213 stands, R201 to R 204 and R 210 to R 213 each independently stand for hydrogen, methyl, ethyl, propyl, butyl, chloroethyl, cyanomethyl, cyanoethyl, methoxyethyl, cyclopentyl, cyclohexyl, cyclohexylmethyl, benzyl, phenyl, tolyl, anisyl or chlorophenyl or NR 201 R 202 , NR 203 R 204 , NR 210 R 211 and NR 212 R 213 independently stand for pyrrolidino, piperidino, morpholino or N-methylpiperazino, R 207 to R 209 stand for hydrogen and the two optional bridge groups X 1 and X 2 stand independently for SiMe2 or O.

3. The photopolymer composition according to any one of the preceding claims, wherein the at least one dye has a structure of formula (XIX), wherein R 201 to R 204 and R 210 to R 2134. The photopolymer composition according to any one of the preceding claims, wherein the at least one dye present according to formula (11) or formula (XIX) comprises an organically substituted sulfonate as the anion (An-).

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

6. The photopolymer composition according to any one of the preceding claims, wherein the at least one co-initiator comprises a triarylalkylborate salt of formula (111). wherein A for a methylene group or for an arbitrarily substituted methine group, optionally with R 100 which can form a ring with up to 10 segments, stands, R 100for hydrogen or for a C1- to C-substituted compound, optionally with hydroxy and / or alkoxy and / or acyloxy and / or halogen 20 -Alkyl-, C3- to C 20 -Alkenyl- , C3- to C 20 -Alkynyl-, C5- to C7-cycloalkyl- or C7- to C 13 -aralkyl group is present, R 101 , R 102 , and R 103 for up to five independently selected residues from C1 to C 20 -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 C 12 -Alkoxy-, trifluoromethoxy-, trichloromethoxy-, C1- to C 12 -alkylthioyl, thioyl, difluoromethoxy, difluoromethylthioyl, carboxyl, carbonyl, 2-, 3-, or 4-pyridyl, or arbitrarily substituted aryl groups or hydrogen, the choice of groups being determined by the fact that the calculated oxidation potential of the triarylalkylborate (111), which depends on the groups, lies in a range between 1.01 V vs. SCE and 1.31 V vs. SCE in acetonitrile, K + for any substituted organocation of valence n based on nitrogen, phosphorus, oxygen, sulfur, and / or iodine, and n represents 1, 2, or 3.

7. The photopolymer composition according to any one of the preceding claims, wherein R 100 for a C1 to C 20 -Alkyl, C5- to C7-cycloalkyl or C7- to Cn-aralkyl group and R 101 , R 102 , and R 103for one or two independently selected residues from C1 to C4 alkyl, halogen, cyano, trifluoromethyl, C1 to C4 alkoxy, or arbitrarily substituted aryl residues or hydrogen.

8. The photopolymer composition according to one of the preceding claims, wherein R 100 for a C3 to C 12 - Alkyl group stands and R 101 , R 102 , and R 103 for one or two independently selected C1 to C4 alkyl groups and halogen substituents, in the meta or para position.

9. The photopolymer composition according to one of the preceding claims, wherein the organocation K +of the triarylalkylborate salt, 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 one of the preceding claims, wherein the at least one co-initiator has an oxidation potential between 1.01 V vs. SCE and 1.20 V vs. SCE in acetonitrile, preferably between 1.02 V and 1.17 V, and particularly preferably between 1.02 V and 1.15 V vs. SCE in acetonitrile.

11. A layer structure comprising at least the layers: A. a substrate layer A, which may be part of a further layer structure, B. a photopolymer layer B formed from the polymer composition according to one of the preceding claims, and C. a top layer C, which may be part of a further layer structure. 2 A layer structure comprising at least the following layers: 1 . A. a substrate layer A, which may be part of a further layer structure, B ' . an exposed photopolymer layer B', which is 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. Holographic medium comprising a photopolymer composition according to any one of claims 1-10 or obtainable using a photopolymer composition according to any one of claims 1-10.

14. Holographic medium according to claim 13, characterized in that the hologram is selected from the group consisting of a reflection, transmission, in-line, off-axis, full-aperture transfer, white-light transmission, Denisyuk, off-axis reflection or edge-lit hologram 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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