Improved fade resistance

Abstract

The present invention relates to UV / VIS photopolymerizable compositions and elements prepared therefrom, and to their uses, in particular to recording materials for optical elements, especially holograms, using refractive index modulation.

Description

[Technical Field]

[0001] This invention relates to UV / VIS photopolymerizable compositions and devices made therefrom, as well as their uses. Specifically, it relates to recording materials for optical devices using refractive index modulation, particularly holograms. [Background technology]

[0002] To cure a photopolymerizable composition using visible light, an appropriate photopolymerization initiator system is required. These initiators absorb the energy of the light, form free radicals, and initiate a chain reaction of radical polymerization. Such systems are publicly known and are described, for example, in the following patents: Patent Document 1 (DuPont), Patent Document 2 (Bayer), and Patent Document 3 (Xetos).

[0003] In this process, dyes are used as sensitizers, and borates as copolymer initiators. The color is chosen to match the light that the system is most susceptible to. It is preferable to use a fluorescent dye that is the complementary color of the exposure wavelength to effectively absorb the energy of that light. For example, magenta dyes are used for green light, blue dyes for red light, and yellow dyes for blue light. In exposures using multiple wavelengths, combinations of dyes are also possible. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] German patent number 69032682T2 [Patent Document 2] International Publication No. 2010091795A1 Pamphlet [Patent Document 3] European Patent No. 1779196B1 [Overview of the project] [Problems that the invention aims to solve]

[0005] To advantageously achieve high photosensitivity, the photopolymerizable composition must develop sufficient and clear color. However, for most applications of exposed elements, a clear, transparent, and colorless layer is desirable. Conveniently, these dyes have poor lightfastness and fade to some extent under UV light. However, since some dyes require some time and strong irradiance, a clearly recognizable residual color usually remains even after UV curing performed after laser exposure. [Means for solving the problem]

[0006] Therefore, the present invention is based on the objective of providing a system that fades faster and more effectively under UV light, without quality degradation or additional work steps. The objective is addressed in the present invention by a photopolymerizable composition comprising the following, which can be cured by UV / VIS irradiation: a) A mixture containing 80-99.8% by weight of radically curable monomers, b) 0.1 to 10% by weight of a photopolymerization initiator system, and c) 0.1 to 10% by weight of bleach, Here, the total amount of a), b), and c) is 100% by weight, and the bleaching agent is effective under chemical irradiation. It is particularly preferable that the bleaching substance is formed solely by chemical irradiation. It is particularly preferable that the bleaching substance is formed from component c) by the action of chemical irradiation.

[0007] Further preferred embodiments are defined in the dependent claims. Activity (chemical beam irradiation) should be understood as the photochemical activity of electromagnetic radiation of various wavelengths. The term is used, for example, when evaluating the physiological effects of laser light of various colors, or the spectral sensitivity of photographic film and paper. In photochemistry, an actinic chemical is one that is susceptible to the effects of light or radiation.

[0008] In the context of this invention, "effective under actinic irradiation" means that "brightening" occurs. The photopolymerizable compositions of the present invention are preferably used to manufacture elements using refractive index modulation, particularly holograms. The preparation of these elements is generally carried out by spatially or interferometrically irradiating a layer of the photopolymerizable composition placed on a support substrate or copying template with modulated radiation. The carrier substrate used to create the elements of the present invention may be glass, plastic, particularly PET, PP, PMMA, polycarbonate, or cellulose di- or triacetate, or paper. During exposure, the photopolymerizable composition is preferably positioned, for example, between two glass plates.

[0009] Preferably, the device contains a component that can be obtained by applying UV / VIS irradiation, preferably chemical beam UV / VIS irradiation, to the photopolymerizable composition of the present invention. Particularly preferred is an element containing a hologram that can be obtained by applying spatially or coherently modulated radiation to the photopolymerizable composition of the present invention. Particularly preferred is the element of the present invention that includes a hologram, which can be obtained in this manner and is bleached by UV irradiation.

[0010] It is preferable to use a manufacturing process that involves re-bleaching the element using UV light after UV / VIS exposure. The element is preferably used as a film, lens, grid, prism, mirror, beam splitter, diffuser, surface relief, optical switch, or sensor. It is particularly preferred for use in head-up displays, laminated glass, data glass optical induction systems, spectrometers, detection systems, safety elements, or labels.

[0011] Another object of the present invention is a method for forming a photostable hologram in a photopolymerizable layer on a substrate surface or a copy master, comprising exposing the layer of the photopolymerizable composition according to the present invention to modulated radiation containing holographic information. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic exposure apparatus of the present invention is shown. [Figure 2] This shows the beam path. [Figure 3] The measurement curve for the corresponding measurement point of sample B is shown. [Figure 4] The spectral absorption curves of two photopolymerized compositions, A and B, before and after 30 seconds of bleaching under UV bridging are shown.

[0013] bleach Surprisingly, it was found that the decay reaction products of certain photopolymerization initiators, generated during chemical beam irradiation, help to fade the dyes more effectively and quickly. These are photopolymerization initiators constructed as follows: aryl ketone compounds represented by the following general formula (1): [ka] [In the formula, Rx and Ry are the same or different and represent the following: a linear or branched alkyl group having 1 to 8 carbon atoms and optionally substituted with 1 hydroxyl group; a cycloalkyl group having 1 to 8 carbon atoms and optionally substituted with 1 hydroxyl group; an alkoxy group having 1 to 8 carbon atoms and optionally substituted with 1 hydroxyl group; an alkoxycarbonyl group (where the alkoxy group has 1 to 8 carbon atoms and optionally substituted with 1 hydroxyl group); a carbamoyl group optionally substituted with a phosphate group; a phosphoryl group optionally substituted with an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 8 carbon atoms; an acyl group or condensed acyl group optionally substituted with 1 hydroxyl group, or a group represented by formula (2);

[0014] [ka] (In equation (2), R 1z ~R 5z These are identical or different and represent a hydrogen atom; an alkyl group having 1 to 8 carbon atoms; an alkenyl group having 2 to 8 carbon atoms; an alkoxy group having 1 to 8 carbon atoms; an alkyl group having 1 to 8 carbon atoms substituted with a halogen atom; an alkoxy group having 1 to 8 carbon atoms substituted with a halogen atom; a halogen atom; a hydroxyl group; a nitro group; a cyano group; an amino group; Here, in equation (2), R 1z ~R 5z Two adjacent groups from various sources may, in some cases, bond to each other and, together with the benzene ring to which they are bonded, form a condensed ring selected from a naphthalene ring, a quinoline ring, an isoquinoline ring, a tetrahydronaphthalene ring, an indan ring, a tetrahydroquinoline ring, and a tetrahydroisoquinoline ring, and R to it 1z ~R 5zThe multiple carbon atoms bonded to two adjacent groups are, in some cases, substituted with 1 to 4 identical or different substituents selected from alkyl groups with 1 to 8 carbon atoms, cycloalkyl groups with 3 to 8 carbon atoms, alkenyl groups with 2 to 8 carbon atoms, alkoxy groups with 1 to 8 carbon atoms and possibly substituted with halogen atoms, hydroxyl groups, nitro groups, cyano groups, and amino groups. Here, at least one of Rx and Ry is represented by equation (2).

[0015] The following photopolymerization initiators and reactions are preferred. [ka]

[0016] Of particular preference is 2-hydroxy-2-methyl-1-phenylpropanone. [ka]

[0017] The bleaching agent c) in the photopolymerizable composition includes one or more of these photopolymerization initiators, their decomposition reaction products, or mixtures thereof. The proportion of a suitable photopolymerization initiator in the bleaching agent is greater than 50% by weight, preferably greater than 90% by weight. It is particularly preferable that the bleaching agent consists of only one or more suitable photopolymerization initiators.

[0018] Preferred decomposition reaction products are benzoyl derivatives and alcohols, with benzaldehyde and 2-propanol being particularly preferred. In the present invention, it is preferable that component c) of the photopolymerizable composition contains a photopolymerization initiator, and it is particularly preferable that the photopolymerization initiator used in component c) generates benzoyl radicals and alcohol radicals under the action of chemical beam irradiation.

[0019] To obtain the desired decomposition reaction product, a mixture of two photopolymerization initiators may be used, in which case, under irradiation, the first photopolymerization initiator forms a benzoyl radical and the second photopolymerization initiator forms an alcohol radical. It is particularly preferable that the bleaching substance and its bleaching effect are obtained solely by chemical irradiation. For these substances to function effectively, they must be used in appropriate amounts, which may be greater than the usual recommended amounts for other photopolymerization initiators. A ratio of at least 1% by weight is preferred, and at least 3% by weight is particularly preferred.

[0020] It is preferable to use photopolymerization initiators that are liquid at room temperature, as they can also function as solvents for the dyes. Therefore, preferably, component c) can be used as one component of the solvent for the dye concentrate. Therefore, a further object of the present invention is a process in which component c) of the photopolymerizable composition in the present invention is used as a solvent for the dye, or as a component of the solvent. A photopolymerization initiator that is as pale yellow as possible under UV light is also preferred.

[0021] monomer-containing mixture The radical reaction-curable monomer-containing mixture contains ethylenically unsaturated monomers capable of radical addition polymerization. The ratio is preferably at least 5% by weight, more preferably at least 40% by weight, and particularly preferably at least 80% by weight. The monomer-containing mixture may further contain a polymeric binder, such as vinyl acetate (German Patent No. 69032682T2), PMMA, or a polyol, in a proportion of less than 95% by weight, preferably less than 60% by weight, and particularly preferably less than 20% by weight. Instead of incorporating the monomer into the polymeric binder, it is also possible to incorporate the monomer into the polyurethane matrix (International Publication No. 2008 / 125229A1, International Publication No. 2012 / 062655A2).

[0022] Additives that improve the performance of the film, such as plasticizers and, for example, fluidizers and degassing agents, may also be included. Alternatively, other inert, non-crosslinked components, such as triglycerides (European Patent No. 1 779 196B1), may be included. The components of the mixture are selected so that the photopolymerizable composition forms a solid layer upon final chemical irradiation. It is preferable that, when the photopolymerizable composition is properly exposed to light, the components of the monomer-containing mixture ensure a refractive index difference of at least 0.005, preferably at least 0.01, and particularly preferably at least 0.02. It is particularly preferable that refractive index modulation with a resolution of more than 1000 lines / mm is generated when recording the hologram. The photopolymerizable composition in the present invention is preferable if it is capable of forming refractive index modulation with amplitude or having a Δn of at least 0.005.

[0023] The refractive index modulation Δn can be calculated using Kogelnik's coupled wave theory, based on the measured diffraction efficiency (BWG) η and layer thickness d (see H. Kogelnik, The Bell System Technical Journal, Volume 48, November 1969, Number 9, pp. 2909-2947).

[0024] For surface mirror reflection holograms or Lippmann-Bragg holograms where the refractive index modulation is parallel to the surface, the following relationship holds:

number

[0025] The diffraction efficiency can be measured in transmitted light at room temperature using a spectrometer (e.g., CAS 140B, manufactured by Instrument Systems). This is carried out using vertical illumination. Since the hologram reflects only wavelengths that satisfy the Bragg condition, at this point, a clear absorption peak is observed in the spectral curve. Peak value T Peak and the reference value T of the upper baseline in the vicinity Ref From these, the diffraction efficiency (BWG) η is calculated by the following formula; η=(T Ref -T Peak ) / T Ref

[0026] The thickness d of that layer can be measured outside the micrometer gauge using a digital micrometer. The refractive index modulation is calculated from those two measured values as follows: [Number]<00003AB><00003AC><00003AD><00003AE><00003AF><00003B0>The monomer-containing mixture forms a substantially clear and transparent layer, which may be solid at room temperature. Particularly preferred is a monomer-containing mixture that is liquid in the temperature range of 20 °C to 150 °C. The viscosity at 20 °C should be at least 2000 mPa·s, preferably 10000 mPa·s, and particularly preferably at least 20000 mPa·s. <00003B1>The viscosity can be measured using a plate-plate rotational rheometer (e.g., manufactured by Haake, type 006-2805). The material is placed between two coaxial circular plates, and one plate is rotated. The distance between those plates is, for example, 1 mm, and the diameter is 35 mm. The viscosity can be determined from the measurement of the torque and speed (e.g., 10 rotations / second) (DIN53018, ISO3210). <00003B2><00003B3><00003B4>Preferably, the monomer-containing mixture contains a polyfunctional monomer having at least two ethylenically unsaturated groups. The monomer-containing mixture preferably consists only of one or more difunctional or higher functional monomers, that is, the composition does not contain monofunctional ethylenically unsaturated monomers. Preferably, the content of monomers having at least two ethylenically unsaturated groups in component c) of the composition of the present invention is greater than 10% by weight, and particularly preferably greater than 30% by weight. By using bifunctional or higher-functional monomers, specifically, the thermal and mechanical stability of the resulting holographic elements is significantly enhanced, which is particularly advantageous in the creation of reflection holograms.

[0029] Preferred monomers having at least two ethylenically unsaturated groups are ethoxylated bisphenol A diacrylates, specifically compounds of the following formula: [ka] (In the formula, n and m are 0 to 12, preferably 1 to 12, o is 0.1; Ar is a mononuclear or polynuclear substituted or unsubstituted aromatic or heterocyclic aromatic group; R1 is hydrogen; and methyl is ethyl.)

[0030] Particularly preferred monomers are compounds with the following structural formula: [ka] The viscosity of the monomer or monomer mixture is preferably at least 900 mPa·s at room temperature.

[0031] Photopolymerization initiator system A photopolymerization initiator system that activates monomer polymerization upon exposure to chemical beam irradiation consists of a photopolymerization initiator, or copolymerization initiator, or co-photopolymerization initiator, and a dye. It is preferable that it contains all three of the above components. Here, the photopolymerization initiator is different from the photopolymerization initiator that is likely to be used in the bleaching composition. It is particularly preferable that the photopolymerization initiator system, i.e., component b), contains only a copolymerization initiator and a dye. In the context of the present invention, "copolymerization initiator" and "co-photopolymerization initiator" are used interchangeably. The dyes act as sensitizers, absorbing the energy of radiation from the near-UV, visible, or near-infrared range, and, with the help of a co-photopolymerization initiator, initiate radical generation reactions.

[0032] pigment The dyes function as sensitizers for co-photopolymerization initiators. Suitable for this purpose include, for example, methylene blue, as well as the sensitizers disclosed in U.S. Patents 3,554,753A, 3,563,750A, 3,563,751A, 3,647,467A, 3,652,275A, 4,162,162A, 4,268,667A, 4,454,218A, 4,535,052A, and 4,565,769A, and as well as the dyes and co-photopolymerization initiators described in International Publication No. 2012062655A2 (which are also expressly referenced herein). Particularly preferred sensitizers include: DBC, i.e., 2,5-bis[(4-diethylamino-2-methylphenyl)methylene]cyclopentanone; DEAW, i.e., 2,5-bis[(4-diethylaminophenyl)methylene]cyclopentanone; dimethoxy-JDI, i.e., 2,3-dihydro-5,6-dimethoxy-2-[(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinoridine-9-yl)methylene]-1H-inden-1-one; and safranin O, i.e., 3,7-diamino-2,8-dimethyl-5-phenylphenadinium chloride.

[0033] The dyes in the photopolymerizable composition of the present invention are preferably fluorescent dyes, and they may consist of, for example, a cationic dye and an anion. The cationic dye is of formula F + It can be expressed as follows. Therefore, equation F + The following formula is preferred for cationic dyes: [ka] [In the formula, X 1 O, S, NR 6 , or CR 6a R 6b This represents, X 2 is N or CR 5 This represents, R 5 These are hydrogen, cyano, C1-C4-alkyl, C4-C7-cycloalkyl, and C6-C 10 -aryl (or C1-C4-alkoxycarbonyl or NR in some cases) 7 R 8 C6-C substituted with a heterocyclic group or a carboxyl group (substituted by a carboxyl group) 10 - Represents aryl, R 6 is hydrogen, C1~C 16 -alkyl, C4-C7-cycloalkyl, C7-C 16 - Aralkir, C6~C 10 - Represents an aryl or heterocyclic group, R 6a and R 6b These represent methyl and ethyl independently, or combined to represent a -CH2-CH2-CH2- or -CH2-CH2-CH2-CH2- bridge, or C6-C substituted with a carboxyl group. 10 - Represents aryl, R 1 ~R 4 , R 7 , and R 8 These are, independently of each other, hydrogen, C1~C16 -alkyl, C4-C7-cycloalkyl, C7-C 16 - Aralkir, C6~C 10 - Represents an aryl or heterocyclic group, or NR 1 R 2 , NR 7 R 4 and NR 7 R 8 These independently represent a 5-membered or 6-membered saturated ring (which is bonded via N and may further contain N or O, and / or be substituted by a nonionic group), or R 1 ~R 4 , R 7 , and R 8 These atoms independently form two- or three-membered bridges with the carbon atoms of the benzene ring adjacent to the nitrogen atoms, and these bridges may contain oxygen or nitrogen, and / or may be substituted with nonionic groups. R 9 , R 9a , R 9b , R 10 , R 10a , and R 10b [Each represents hydrogen, halogen, or C1-C4 alkyl independently of the others]

[0034] [ka] [In the formula, R 15 This includes hydrogen, halogens, C1-C4 alkyl, C1-C4 alkoxy, or NR 18 R 19 This represents, R 11 ~R 14 , R 18 , and R 19 , independently of each other, hydrogen, C1~C 16 -alkyl, C4-C7-cycloalkyl, C7-C 16 - Aralkir, C6~C 10 - Represents an aryl or heterocyclic group, or NR11 R 12 , NR 13 R 14 and NR 18 R 19 These independently represent a 5-membered or 6-membered saturated ring (which is bonded via N and may further contain N or O, and / or be substituted by a nonionic group), or R 12 , R 17b , R 13 , R 17c , and R 18 ;R 17a These independently form two- or three-membered bridges, which may contain O or N and / or be substituted with nonionic groups. R 16 This represents hydrogen, chlorine, methyl, methoxycarbonyl, or ethoxycarbonyl. R 16a This represents hydrogen, chlorine, or methyl. R 17a , R 17b , and R 17c These elements independently represent hydrogen, chlorine, methyl, or methoxy.

[0035] Nonionic groups include C1-C4-alkyl, C1-C4-alkoxy, halogen, cyano, nitro, C1-C4-alkoxycarbonyl, C1-C4-alkylthio, C1-C4-alkanoylamino, benzoylamino, and mono- or di-C1-C4-alkylamino. Alkyl, alkoxy, cycloalkyl, aryl, and heterocyclic groups may optionally be further supported with groups such as alkyl, halogen, nitro, cyano, CO-NH2, alkoxy, trialkylsilyl, trialkylsiloxy, or phenyl, and the alkyl and alkoxy groups may be linear or branched, the alkyl groups may be partially or fully halogenated, the alkyl and alkoxy groups may be ethoxylated, propoxylated, or silylated, adjacent alkyl and / or alkoxy groups on the aryl or heterocyclic group may combine to form a three-membered or four-membered bridge, and the heterocyclic group may be benzo-condensed and / or quaternized.

[0036] The term "halogen" means fluorine, chlorine, bromine, or iodine, preferably fluorine, chlorine, or bromine. Examples of substituted alkyl groups include trifluoromethyl, chloroethyl, cyanomethyl, cyanoethyl, and methoxyethyl. Examples of branched alkyl groups include isopropyl, tert-butyl, 2-butyl, and neopentyl. Examples of alkoxy groups include methoxy, ethoxy, and methoxyethoxy.

[0037] Suitable, and possibly substituted, C1-C4 alkyl groups are: methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, tert-butyl, perfluorinated methyl, perfluorinated ethyl, 2,2-trifluoroethyl, 3,3,3-trifluoroethyl, perfluorobutyl, cyanoethyl, methoxyethyl, and chloroethyl. Suitable aralkyls include, for example, benzyl, phenethyl, or phenylpropyl. C6~C 10Examples of -aryl are phenyl and naphthyl. Examples of substituted aryl groups are tolyl, chlorophenyl, dichlorophenyl, methoxyphenyl, nitrophenyl, cyanophenyl, dimethylaminophenyl, and diethylaminophenyl.

[0038] Examples of heteroaryl groups, especially 5- or 6-membered heterocyclic groups, are indolyl, pyridyl, quinolyl, and benzothiazolyl. Examples of substituted heterocyclic groups are 1,2-dimethylindol-3-yl and 1-methyl-2-phenylindol-3-yl. Formula F + The anion for the cationic dye of may be, for example, an anion of halogen, sulfate, carbonate, or nitrate.

[0039] Particularly preferred cationic dyes are malachite green, methylene blue, safranine O, and rhodamine of formula III. [Chemical formula] [wherein, R a , R b , R c , R d , R e , R f , and R g each represent H or an alkyl group, and X - represents chloride ion, trifluoromethanesulfonate, naphthalenedisulfonate, para-toluenesulfonate, hexafluorophosphate, perchlorate, meta-nitrobenzenesulfonate or meta-aminobenzenesulfonate, for example, rhodamine B, rhodamine 6G or violamine R as shown below, and further represents sulforhodamine B or sulforhodamine G].

[0040] Rhodamine B: [Chemical formula] Rhodamine 6G: [Chemical formula] Violamin R: [ka] Sulfolodamine B: [ka] Sulforodamine G: [ka]

[0041] Other suitable dyes are fluorones, as described in Neckers et al., J. Polym. Sci., Part A, Poly. Chem., 1995, 33, 1691-1703. Of particular interest are the following compounds: [ka]

[0042] Other suitable examples of pigments include cyanines of formula IV: [ka] [In the formula, R IV = alkyl; n 1 = 0, 1, 2, 3, or 4, and Y1 = CH=CH, N-CH3, C(CH3)2, O, S, or Se. Preferably, Y1 in formula IV is a cyanine in which C(CH3)2 or S.

[0043] The dye in the photopolymerizable composition of the present invention is preferably selected from the group consisting of the following: acriflavin, diaminoacridine, rhodamine B, safranin-O, diethylsafranin, and methylene blue.

[0044] Photopolymerization initiator Preferably, the photopolymerization initiator system, i.e., component b) of the photopolymerizable composition, includes a photopolymerization initiator. In the present invention, it is preferable that the photopolymerization initiator in the photopolymerizable composition can generate radicals when irradiated with a wavelength between 100 nm and 480 nm, preferably between 150 nm and 460 nm, and more preferably between 200 nm and 380 nm.

[0045] Radical-forming polymerization initiators are well known; see, for example, the following literature: H.J. Timpe and S. Neuenfeld, “Dyes in Photoinitiator System”. Contacts (1990), pp. 28-35, and J. Jakubiak and J. F. Abek, “Photoinitiators for visible light polymisation”, Polymery (Warsaw) (1999), 44, pp. 447-461.

[0046] Suitable radical-forming polymerization initiators that can be activated by UV irradiation and are generally inert at temperatures up to 185°C include substituted or unsubstituted polynuclear quinones, which are compounds having two intracyclic carbon atoms in a conjugated carbocyclic ring system, and include, for example: 9,10-anthraquinone, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,4-naphthoquinone, 9,10- Enanthrenequinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-methyl-1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1,4-dimethylanthraquinone, 2,3-dimethylanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, sodium salt of anthraquinone-α-sulfonic acid, 3-chloro-2-methylanthraquinone, retenquinone, 7,8,9,10-tetrahydronaphthacenequinone, and 1,2,3,4-tetrahydrobenz[a]anthracene-7,12-dione. Other useful photopolymerization initiators (some of which are thermally activated at low temperatures of around 85°C) are described in U.S. Patent No. 2,760,663, and include, for example, vicinal ketoaldonyl alcohols such as benzoin and pivaloin; acyloin ethers such as methyl and ethyl ethers of benzoin; and α-hydrogen-substituted aromatic acyloins such as α-methylbenzoin, α-allylbenzoin, and α-phenylbenzoin.

[0047] The following can be used as photopolymerization initiators: photoreducing dyes and reducing agents, for example, those disclosed in U.S. Patent Nos. 2,850,445A, 2,875,047A, 3,097,096A, 3,074,974, 3,097,097A, 3,145,104, and 3,579,339A; and also phenazine, oxazine Dyes from the classes of quinones and benzophenones; Michler ketones, benzophenones, 2,4,5-triphenylimidazolyl dimers with hydrogen donors, and mixtures thereof, as described in U.S. Patent Nos. 3,427,161A, 3,479,185A, 3,549,367A, 4,311,783A, 4,622,286A, and 3,784,557A. Useful considerations regarding dye-sensitized photopolymerization can be found in the following literature: DFEaton, “Dye Sensitized Photopolymerization”, Adv. in Photochemistry, vol.13 (DH Volman, G. Shammond and K. Gollnick, eds, Wiley-Interscience, New York, 1986), pp. 427-487. Similarly, the cyclohexadienone compounds of U.S. Patent No. 4,341,860 are also useful as polymerization initiators. Other suitable photopolymerization initiators include: CDM-HABI, i.e., 2-(o-chlorophenyl)-4,5-bis(m-methoxyphenyl)-imidazole dimer; o-Cl-HABI, i.e., 2,2'-bis-(o-chlorophenyl)-4,4',5,5'-tetraphenyl-1,1'-biimidazole; and TCTM-HABI, i.e., 2,5-bis(o-chlorophenyl)-4-(3,4-dimethoxyphenyl)-1H-imidazole dimer, each typically used with a hydrogen donor, such as 2-mercaptobenzoxazole.

[0048] Particularly preferred photopolymerization initiators include, for example, the following UV photopolymerization initiators: IRGACURE® OXE-01 (1,2-octanedione-1-[4-(phenylthio)-phenyl]-2-(O-benzoyl oxime), and IRGACURE® OXE-02 (1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-O-acetyloxime (manufactured by BASF AG), as well as OMNIRAD-MBF (methylbenzoyl formate), OMNIRAD-TPO (2,4,6-trimethylbenzoyl-diphenylphosphine oxide), OMNIRAD-TPO-L (ethyl-(2,4,6-trimethylbenzoyl)-phenylphosphine), OMNIRAD-1173 (2-hydroxy-2-methyl-1-phenylpropanone), OMNIRAD 1000 (a mixture of 2-hydroxy-2-methyl-1-phenylpropanone (80%) and 1-hydroxycyclohexyl-phenyl ketone (20%)), OMNIRAD 184 (1-hydroxycyclohexyl-phenyl ketone), OMNIRAD 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide), OMNIRAD 2022 (a mixture of 2-hydroxy-2-methyl-1-phenylpropanone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and ethyl(2,4,6-trimethylbenzoyl)phenylphosphine), and OMNICAT 440 (4,4'-dimethyl-diphenyl-iodonium-hexafluorophosphate) are available from IGM Resins and are preferably used in amounts of 0.1 to 10% by weight.

[0049] [ka]

[0050] The photopolymerization initiators described above may be used alone or in combination. Preferably, the photopolymerization initiator is liquid and / or is selected from the group consisting of: 1,2-octanedione-1-[4-(phenylthio)-phenyl]-2-(O-benzoyloxime), (1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-O-acyloxime, methyl benzoylformate), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate), 2-hydroxy-2-methyl-1-phenylpropanone, a mixture of 2-hydroxy-2-methyl-1-phenylpropanone (80%) and 1-hydroxycyclohexyl-phenylketone (20%), 1-hydroxycyclohexyl-phenylketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenylpropanone, a mixture of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate), and 4,4'-dimethyl-diphenyl-iodonium hexafluorophosphate. Preferably, the photopolymerization initiator system, i.e., component b) of the photopolymerizable composition, contains a co-photopolymerization initiator.

[0051] Co-photopolymerization initiator Preferably, the co-photopolymerization initiator used in the composition according to the present invention contains a compound of formula (I). [Chemical formula] [In the formula, R 1c represents C1-C 20 -alkyl, C3-C 12 -cycloalkyl, C₂-C₈-alkenyl, phenyl-C1-C₆-alkyl, or naphthyl-C1-C₃-alkyl, where the groups C1-C 20 -alkyl, C3-C 12 -cycloalkyl, C₂-C₈-alkenyl, phenyl-C1-C₆-alkyl, or naphthyl-C1-C₃-alkyl are each independently substituted with one or more groups O, S(O)p , or NR 5c They may be interrupted by or their base C1~C 20 -alkyl, C3~C 12 -Cycloalkyl, C2-C8-alkenyl, phenyl-C1-C6-alkyl, or naphthyl-C1-C3-alkyl is either unsubstituted or C1-C 12 -alkyl, OR6, R 7c S(O) p , R 7c S(O)2O, NR 8c R 9c , SiR 10c R 11c R 12c , BR 13c R 14c , or R 15c R 16c P(O) q Replaced by;R 2c , R 3c and R 4c These are independently phenyl or biphenyl, and the phenyl or biphenyl group is either unsubstituted or substituted by the following groups: OR 6c , NR 8c R 9c , or halogen-substituted C1~C 12 -alkyl, OR 6c , R 7c S(O) p , R 7c S(O)2O, R 8c R 9c NS(O)2, NR 8c R 9c , NR 3c R 8c CO,

[0052] [ka] SiR 10c R 11c R 12c , BR 13c R 14c , halogen, R 15c R 16c P(O) q , [ka] R 5c is hydrogen, C1~C 12 -alkyl, phenyl-C1~C6-alkyl (this is either unsubstituted or C1~C6-alkyl, C1~C 12 - substituted 1 to 5 times with alkoxy or halogen, or phenyl (which is unsubstituted or C1-C6 alkyl, C1-C 12 - Substituted 1 to 5 times with alkoxy or halogen; R 6c and R 7c C1~C 12 -alkyl (which is either unsubstituted or substituted with a halogen), phenyl-C1~C6-alkyl (which is either unsubstituted or C1~C6-alkyl, C1~C 12 - substituted 1 to 5 times with alkoxy or halogen, or phenyl (which is unsubstituted or C1-C6 alkyl, C1-C 12 - Represents a compound that is substituted 1 to 5 times with an alkoxy or halogen; R 8c , R 9c , R 10c , R 11c , R 12c , R 13c , R 14c , R 15c , and R 16c These are independent of each other, C1~C 12 -alkyl, C3~C 12 -Cycloalkyl (this is either unsubstituted or C1-C6 alkyl, C1-C 12 - substituted 1 to 5 times with alkoxy or halogen, or halogen-substituted phenyl C1-C6-alkyl (which is either unsubstituted or C1-C6-alkyl, C1-C 12 -substituted 1 to 5 times with alkoxy or halogen-substituted phenyl, or R 8c and R 9cHowever, they combine with the N-atom to which they are bonded to form a six-membered aliphatic ring, which may further contain oxygen or sulfur as additional heteroatoms; R 17c , R 18c , R 19c , and R 20c These are, independently of each other, hydrogen, C1~C 12 -alkyl (this is either unsubstituted or C1-C) 12 -substituted with alkoxy or phenyl), or phenyl-C1~C6-alkyl, group phenyl, or phenyl-C1~C6-alkyl (unsubstituted, or C1~C6-alkyl, C1~C 12 -It is monosubstituted to pentasubstituted by an alkoxy or halogen; p is a number between 0 and 2; r represents a number from 0 to 5; R 21c is hydrogen, or C1~C 12 -It is alkyl; R 22c , R 22a , R 23c , and R 24c These are, independently of each other, hydrogen, C1~C 12 -alkyl (this is either unsubstituted or C1-C) 12 -substituted with alkoxy, OH, or halogen, or phenyl (which is unsubstituted or C1-C) 12 - Represents a compound (substituted with an alkoxy, OH, or halogen); q represents 0 or 1; and G represents a residue capable of forming a positive ion.

[0053] The co-photopolymerization initiator in the photopolymerizable composition of the present invention is preferably selected from the group consisting of tetrabutylammonium tetrahexylborate, tetrabutylammonium triphenylhexylborate, tetrabutylammonium tris-(3-fluorophenyl)-hexylborate, and tetrabutylammonium tris-(3-chloro-4-methylphenyl)-hexylborate, or mixtures thereof. A co-photopolymerization initiator having structural formula (Ia), as shown below, developed by Ciba Specialty Chemicals, Inc. under the name "CGI7460" and currently available from BASF AG under the name "SEC LCA1460," is highly preferred. [ka] [Examples]

[0054] The following dyes were used in the bleaching test.

[0055] [Table 1]

[0056] UV initiator These UV initiators were compared to each other for bleaching tests. [Table 2]

[0057] [Table 3]

[0058] solvent In the bleaching test, the following solvents were used for the dye and the powdered UV photopolymerization initiator. Low molecular weight polycaprolactone (PCL-triol) was used as the solvent, but it did not affect the bleaching process.

[0059] [Table 4]

[0060] Bleaching test To test the compatibility of photopolymerization initiators and solvents for improving the fading of dyes, saturated dye solutions were prepared using them. For this purpose, 1-2 spatula-fulls (approximately 0.1-0.2 g) of dye were placed in a small 1.5 mL cuvette. 2-4 spatula-fulls (approximately 0.2-0.4 g) of powdered UV photopolymerization initiator were also added, and the entire solution was filled with polycaprolactone triol (PCL-triol). For mixtures using liquid UV photopolymerization initiator and solvent, it was sufficient to completely fill the cuvette. A mixture of pure PCL-triol and dye was used as a reference because no improvement in fading was observed in those solutions.

[0061] The mixtures were thoroughly stirred and kept in an oven at 120°C for 1-2 hours. The samples were then centrifuged to allow the insoluble components to settle at the bottom. A small amount of the supernatant was collected using a pipette and placed as a droplet on a glass slide. For comparison, droplets of another reference solution were placed to the right and left of this droplet. The entire mixture was then covered with a second glass slide.

[0062] These samples could now be measured and bleached. To bleach them, the samples were placed under a UV bridge with an arc length of 70 mm and an output of 120 W / cm for 30 seconds. Before and after bleaching, the samples were observed visually, and their spectral absorption curves were measured using a spectrometer.

[0063] All tests showed that the dye faded best in a mixture of Omnirad 1173 and benzaldehyde. Adding 2-propanol to other UV photopolymerization initiator mixtures partially improved their effect on fading.

[0064] Photopolymerizable composition As an example of the effects of the present invention, two photopolymerizable compositions were prepared using safranin-O dye. First, two dye concentrates and monomer-containing mixtures were mixed.

[0065] [Table 5]

[0066] [Table 6]

[0067] [Table 7]

[0068] For hologram exposure, two photopolymerizable compositions were prepared from the monomer-containing mixtures listed above and two dye concentrates. The mixture using dye concentrate FK1 was used as a comparative example.

[0069] [Table 8]

[0070] [Table 9]

[0071] Preparation method First, prepare the colored concentrate and monomer-containing mixture. Add each component to a beaker one after another while magnetically stirring. For this purpose, place the beaker on a scale to ensure that the liquid substance is added in the correct amount. Next, heat the entire mixture to 120°C while stirring on a heatable magnetic stirrer. Weigh the powdered substance using a weighing bowl and add it to the mixture while stirring. Stir the mixture at 120°C for about 1 hour, then filter the solution and fill it into bottles. The dye concentrate and the monomer-containing mixture are mixed (for example, by shaking using a high-speed mixer or stirring with a stirring rod) to produce a photopolymerizable composition.

[0072] exposure [Table 10]

[0073] Photopolymerizable compositions A and B were exposed to a laser with a wavelength of 532 nm at a temperature range of 20°C to 21°C. The photopolymerizable compositions were stored in an oven at 80°C and exposed immediately after application. After laser exposure and rapid UV curing using a UV flash, the spectral absorption curves were measured using a spectrometer. Subsequently, the samples were post-cured under a UV bridge for an additional 30 seconds to bleach them. The difference in bleaching between the two samples was clearly observed visually and by measuring the spectral absorption again. The diffraction efficiency (BWG, "Beugungswirkungsgrad") was also determined using the spectral absorption curves. Additional transparency measurements were performed using a haze meter. The film thickness was measured outside the micrometer gauge using a digital micrometer.

[0074] Exposure configuration A laser beam with a measured output of 4.0W was horizontally expanded using a multifaceted mirror scanner and focused by a cylindrical lens to cover an exposure width of 23cm. Figure 1 schematically shows the exposure apparatus. Reference numerals in Figure 1: 1. Laser 532nm 2 Mirror 3. Multi-faceted scanner 4. Cylindrical lens 5 Scanning beam 6 Scanner Mirror

[0075] Each sample was scanned and exposed using a movable mirror on this line. The movement speed was set to 9 mm / second. The laser beam struck the sample surface at an angle of 22 degrees to perpendicular.

[0076] Figure 2 shows the beam path. Reference numerals in Figure 2: 1. Scanning beam 532nm 2 Scanner mirror 3. Exposure direction 4. Exposure angle: 22 degrees 5. Substrate, glass, or foil 6. Photosensitive polymers (photopolymerizable compositions) 7. Original plate, mirror plate

[0077] To create a reflective hologram, the sample material was coated onto a mirror plate that reflects laser light. Interference between the incident and reflected beams creates a line pattern of light and dark spots parallel to the surface of the mirror. These interference fringes are recorded by the photopolymerizable composition in the form of refractive index modulation, creating a so-called Lippmann-Bragg hologram.

[0078] When using laser exposure, the photosensitive polymer layer is located between the mirror sheet and a transparent substrate, such as a PET film or glass. In these examples, a glass slide substrate was used. The glass was used to cover the droplets applied to the mirror sheet. The layer thickness is determined by the amount of the droplets and their spread. The size of the circular spread can be adjusted by the contact pressure, temperature, and flow time. Spacers can also be used to achieve the desired layer thickness. After laser exposure, the photopolymerizable composition is cured using UV light. In the first curing step, a UV flash with an output of 3000 WS was used. This is then sufficient to remove the hologram from the sheet along with the carrier. Pretreatment with a primer should be performed to ensure adhesion to the glass. To perform the final curing and bleaching of these samples, a UV bridge with an arc length of 70 mm and an output of 120 W / cm was used. The light source was a mercury vapor lamp. The exposure or bleaching time was 30 seconds.

[0079] Measuring device These samples were measured in transmitted light using a spectrometer (CAS 140B, Instrument Systems). This was performed using vertical illumination. Since the hologram reflects only wavelengths that satisfy the Bragg condition, a clear absorption peak is observed in the spectral curve at this point. Peak value T Peak And the reference value T of the neighboring upper baseline. Ref From this, the diffraction efficiency (BWG)η is calculated by the following equation; η=(T Ref -T Peak ) / T Ref

[0080] Figure 3 shows the measurement curve for the corresponding measurement point of sample B. The exposure table (Table 6) shows that both samples achieved high diffraction efficiencies exceeding 80%, but exposed sample B was far more transparent. Figure 4 shows the spectral absorption curves of the two photopolymerized compositions A and B before and after 30 seconds of bleaching under a UV bridge. Transparency values ​​were measured using a haze meter (haze-gard i, BYK) with a 4 mm aperture diaphragm, following the standard procedure of ASTM D 1003.

Claims

1. A photopolymerizable composition that can be cured by UV / VIS irradiation, (a) A mixture containing 80 to 99.8% by weight of radically curable monomers, b) 0.1 to 10% by weight of a photopolymerization initiator system, and c) 0.1 to 10% by weight of bleach, Includes, The total amount of a), b), and c) is 100% by weight, and the bleach exhibits its performance under chemical irradiation. The photopolymerization initiator system comprises a dye and a copolymerization initiator. Component c) contains a photopolymerization initiator, The photopolymerization initiator used in component c) generates benzoyl radicals and alcohol radicals under the action of chemical irradiation, A photopolymerizable composition in which the copolymer initiator is selected from the group consisting of tetrabutylammonium tetrahexylborate, tetrabutylammonium triphenylhexylborate, tetrabutylammonium tris-(3-fluorophenyl)-hexylborate, and tetrabutylammonium tris-(3-chloro-4-methylphenyl)-hexylborate, or mixtures thereof.

2. The photopolymerizable composition according to claim 1, wherein the dye is selected from the group consisting of acriflavin, diaminoacridine, rhodamine B, safranin-O, diethylsafranin, and methylene blue.

3. The photopolymerizable composition according to any one of claims 1 to 2, wherein the bleaching agent is formed from component c) by the action of chemical irradiation.

4. The photopolymerizable composition according to any one of claims 1 to 3, wherein the photopolymerizable composition is capable of forming a refractive index modulation having a magnitude of at least 0.005, i.e., Δn.

5. A device comprising a component that can be obtained by treating a photopolymerizable composition according to any one of claims 1 to 4 with UV / Vis radiation, preferably chemical UV / Vis radiation.

6. The element according to claim 5, comprising a hologram that can be obtained by exposing the photopolymerizable composition according to any one of claims 1 to 4 to spatially or coherently modulated radiation.

7. Use of the element according to any one of claims 5 and 6, as a film, lens, grid, prism, mirror, beam splitter, diffuser, surface relief, optical switch, or sensor.

8. Use of the element according to any one of claims 5 and 6, for use in a head-up display, laminated glass, data glass, optical induction system, spectrometer, detection system, safety element, or label.

9. A method for creating an element according to any one of claims 5 and 6, wherein UV light is used to post-bleach the element.

10. A process wherein component c) of the photopolymerizable composition according to any one of claims 1 to 4 is used as a solvent or as a component of the solvent for the dye.

11. A method for forming a photostable hologram in a photopolymerizable layer on a substrate surface or a copy master, comprising exposing a layer of the photopolymerizable composition according to any one of claims 1 to 4 to modulated radiation carrying holographic information.

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