Photopolymer composition, holographic recording medium, method for producing same, and optical element including same

Abstract

The present invention relates to a photopolymer composition, a holographic recording medium, a method for producing the same, and an optical element including the same. The photopolymer composition contains an electron donor having a reaction energy of -25 kJ / mol to 0 kJ / mol with a photosensitive dye excited to a triplet state, and therefore not only has excellent optical recording properties such as diffraction efficiency, which is a basic physical property of a holographic recording medium, but also has excellent high-temperature aging stability before recording optical information, and can exhibit the intended optical recording properties even when stored at room temperature to high temperature for a long time, thereby providing a holographic recording medium capable of reproducing a clear image without problems such as halo.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0146071 dated November 4, 2022 and Korean Patent Application No. 10-2022-0146074 dated November 4, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present application relates to a photopolymer composition, a holographic recording medium, a method for producing the same, and an optical element including the same. [Background technology]

[0003] A hologram recording medium records information by changing the refractive index in a holographic recording layer through an exposure process, and reproduces the information by reading the difference in the refractive index recorded in this manner.

[0004] In this regard, the photopolymer composition can be used to manufacture holograms. Photopolymers can easily store optical interference patterns as holograms by photopolymerization of photoreactive monomers. Therefore, photopolymers can be used in a variety of fields, such as smart devices such as mobile devices, parts of wearable displays, vehicle accessories (e.g., head up displays), holographic fingerprint recognition systems, optical lenses, mirrors, deflection mirrors, filters, diffusion screens, diffraction members, light guides, wave guides, holographic optical elements having the functions of projection screens and / or masks, media and optical diffusion plates in optical memory systems, optical wavelength splitters, reflective and transmissive color filters, and the like.

[0005] Specifically, the photopolymer composition for producing holograms includes a polymer matrix, a photoreactive monomer, and a photoinitiator system, and a photopolymer layer made from such a composition is irradiated with coherent laser light to induce localized photopolymerization of the monomer.

[0006] This local photopolymerization process induces a refractive index modulation, which generates a diffraction grating. The refractive index modulation value (Δn) is affected by the thickness and diffraction efficiency (DE) of the photopolymer layer, and the angular selectivity is wider with decreasing thickness.

[0007] Recently, there has been an increasing demand for the development of materials that have high diffraction efficiency and can stably maintain holograms, and various attempts are being made to manufacture holographic recording media that have high diffraction efficiency and refractive index modulation values ​​while being thin.

[0008] On the other hand, the holographic recording medium is required to have excellent stability over time and exhibit the originally intended optical recording characteristics even before recording optical information, but the holographic recording medium has a limitation that the originally intended optical recording characteristics are not exhibited due to the reaction of the photoinitiator system during storage. Summary of the Invention [Problem to be solved by the invention]

[0009] According to one embodiment of the present invention, a photopolymer composition is provided.

[0010] According to another embodiment of the present invention, a holographic recording medium is provided.

[0011] According to yet another embodiment of the present invention, there is provided a method for manufacturing the holographic recording medium.

[0012] According to yet another embodiment of the present invention, there is provided an optical element including the holographic recording medium. [Means for solving the problem]

[0013] Hereinafter, a photopolymer composition, a holographic recording medium, a method for producing the same, and an optical element including the same according to specific embodiments of the present invention will be described.

[0014] In the present specification, unless otherwise specified, the term "hologram recording medium" refers to a medium on which optical information can be recorded in the entire visible light range and ultraviolet light range (e.g., 300 nm to 1,200 nm) by an exposure process. Therefore, the hologram recording medium in the present specification may refer to a medium on which optical information is recorded, or a medium before recording in a state in which optical information can be recorded. The hologram in the present specification may include all visual holograms such as in-line (Gabor) holograms, off-axis holograms, full-aperture transfer holograms, white light transmission holograms ("rainbow holograms"), Denisyuk holograms, off-axis reflection holograms, edge-literature holograms, or holographic stereograms.

[0015] According to one embodiment of the invention, there is provided a photopolymer composition comprising: a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer; and a photoinitiator system including a photosensitive dye and a coinitiator, the coinitiator including an electron donor having a reaction energy of −25 nm to 0 kJ / mol with the photosensitive dye excited to a triplet state.

[0016] The present inventors have confirmed through experiments that when a photosensitive dye exhibiting a specific reaction energy is used in combination with an electron donor as a photoinitiator system of a photopolymer composition for forming a holographic recording medium, a holographic recording medium can be provided that has excellent optical recording characteristics and excellent stability over time from room temperature to high temperatures, and is capable of reproducing a clear image without problems such as halos, and have thus completed the present invention.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A photopolymer composition according to an embodiment of the present invention, a holographic recording medium formed from the photopolymer composition, a method for producing the same, and an optical element including the holographic recording medium will now be described in detail.

[0018] The photopolymer composition of one such embodiment includes a polymeric matrix or a precursor thereof that acts as a support for the photopolymer layer formed therefrom.

[0019] The polymer matrix is ​​formed by crosslinking a siloxane-based polymer containing a silane functional group (Si-H) and a (meth)acrylic polyol. Specifically, the polymer matrix is ​​formed by crosslinking a (meth)acrylic polyol with a siloxane-based polymer containing a silane functional group. More specifically, the hydroxyl group of the (meth)acrylic polyol can form a crosslink with the silane functional group of the siloxane polymer by a hydrosilylation reaction. The hydrosilylation reaction can be carried out quickly even at a relatively low temperature (for example, at a temperature of about 60°C) under a Pt-based catalyst. Therefore, the photopolymer composition can improve the manufacturing efficiency and productivity of the holographic recording medium by adopting a polymer matrix that can be crosslinked quickly even at a relatively low temperature as a support.

[0020] The polymer matrix can increase the mobility of components (e.g., photoreactive monomers or plasticizers) contained in the photopolymer composition due to the flexible backbone of the siloxane-based polymer. In addition, the siloxane bond, which has excellent heat resistance and humidity and heat resistance, can easily ensure the reliability of the photopolymer layer on which optical information is recorded and the holographic recording medium including the same.

[0021] The polymer matrix may have a relatively low refractive index, thereby enhancing the refractive index modulation of the photopolymer layer. For example, the upper limit of the refractive index of the polymer matrix may be 1.53 or less, 1.52 or less, 1.51 or less, 1.50 or less, or 1.49 or less. And, the lower limit of the refractive index of the polymer matrix may be, for example, 1.40 or more, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more. In this specification, the "refractive index" may be a value measured by an Abbe refractometer at 25°C.

[0022] The photopolymer composition includes a polymer matrix formed by crosslinking the siloxane-based polymer containing the silane functional group and the (meth)acrylic polyol, and may include a polymer matrix precursor that is not partially crosslinked. In this case, the polymer matrix precursor may refer to the siloxane-based polymer, the (meth)acrylic polyol, and the Pt-based catalyst.

[0023] The siloxane-based polymer may include, for example, a repeating unit represented by the following Chemical Formula 1 and an end group represented by the following Chemical Formula 2.

[0024] [ka]

[0025] In the above Chemical Formula 1, Multiple R 1 and R 2 are the same or different and each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms, n is an integer from 1 to 10,000.

[0026] [ka] In the above Chemical Formula 2, Multiple R 11~R 13 are the same or different and each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms, At least one repeating unit of the repeating unit represented by the chemical formula 1 and one of the terminal groups of the terminal group represented by the chemical formula 2 1 , R 2 and R 11 ~R 13 At least one of is hydrogen.

[0027] In Chemical Formula 2, -(O)- means that when the Si of the terminal group represented by Chemical Formula 2 is bonded to the repeating unit represented by Chemical Formula 1, it is bonded via oxygen (O) or directly without oxygen (O).

[0028] As used herein, the term "alkyl group" may be a straight-chain, branched-chain or cyclic alkyl group. As a non-limiting example, the term "alkyl group" as used herein may be methyl, ethyl, propyl (e.g., n-propyl, isopropyl, etc.), butyl (e.g., n-butyl, isobutyl, tert-butyl, sec-butyl, cyclobutyl, etc.), pentyl (e.g., n-pentyl, isopentyl, neopentyl, tert-pentyl, 1,1-dimethyl-propyl, 1-ethyl-propyl, 1-methyl-butyl, cyclopentyl, etc.), hexyl (e.g., n-hexyl, 1-methylpentyl, 2 ... pentyl, 4-methylpentyl, 3,3-dimethylbutyl, 1-ethyl-butyl, 2-ethylbutyl, cyclopentylmethyl, cyclohexyl, etc.), heptyl (e.g., n-heptyl, 1-methylhexyl, 4-methylhexyl, 5-methylhexyl, cyclohexylmethyl, etc.), octyl (e.g., n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, etc.), nonyl (e.g., n-nonyl, 2,2-dimethylheptyl, etc.), and the like.

[0029] As an example, R 1 , R 2 and R 11 ~R13 is methyl or hydrogen, and multiple R 1 , R 2 and R 11 ~R 13 At least two of R in the formula 1 may be hydrogen. 1 and R 2 are methyl and hydrogen, and R 11 ~R 13 are each independently methyl or hydrogen (e.g., polymethylhydrosiloxane having a terminal group of a trimethylsilyl group or a dimethylhydrosilyl group); 1 and R 2 are methyl and hydrogen, respectively, and the remaining R 1 and R 2 are all methyl; and R 11 ~R 13 are each independently methyl or hydrogen (e.g., poly(dimethylsiloxane-co-methylhydrosiloxane) having a terminal group of trimethylsilyl or dimethylhydrosilyl); or R 1 and R 2 are all methyl; and R 11 ~R 13 and the remaining are each independently methyl or hydrogen (for example, polydimethylsiloxane in which one or all of the terminal groups are dimethylhydrosilyl groups).

[0030] The siloxane-based compound may have a number average molecular weight (Mn) in the range of 200 to 4,000, for example. Specifically, the lower limit of the number average molecular weight of the siloxane-based polymer may be, for example, 200 or more, 250 or more, 300 or more, or 350 or more, and the upper limit may be, for example, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less, 1,500 or less, or 1,000 or less. When the number average molecular weight of the siloxane-based polymer satisfies the above range, problems such as the siloxane-based polymer volatilizing during the crosslinking process with the (meth)acrylic polyol performed at room temperature or higher, resulting in a decrease in the degree of matrix crosslinking, or the siloxane-based polymer having poor compatibility with other components of the photopolymer composition and phase separation occurring with such components, can be prevented, thereby allowing the holographic recording medium to exhibit excellent optical recording properties and thermal stability.

[0031] The number average molecular weight means a polystyrene-equivalent number average molecular weight (unit: g / mol) measured by the GPC method. In the process of measuring the polystyrene-equivalent number average molecular weight measured by the GPC method, a commonly known analyzer, a detector such as a refractive index detector, and an analytical column can be used, and commonly applied temperature conditions, solvents, and flow rates can be applied. Specific examples of the measurement conditions include a temperature of 30° C., a tetrahydrofuran solvent, and a flow rate of 1 mL / min.

[0032] The silane functional group (Si-H) equivalent of the siloxane-based polymer may be, for example, in the range of 30 g / equivalent to 200 g / equivalent. More specifically, the silane functional group (Si-H) equivalent of the siloxane-based polymer may be 50 g / equivalent or more, 60 g / equivalent or more, 70 g / equivalent or more, 80 g / equivalent or more, or 90 g / equivalent or more, and 180 g / equivalent or less, or 150 g / equivalent or less.

[0033] In this specification, "equivalent weight of a certain functional group" is abbreviated to gram equivalent (equivalent weight) expressed in units of g / equivalent, and means the value obtained by dividing the molecular weight (weight average molecular weight, number average molecular weight, etc.) of a molecule or polymer containing the functional group by the number of the functional group. Therefore, the smaller the equivalent value, the higher the density of the functional group, and the larger the equivalent value, the lower the density of the functional group.

[0034] When the silane functional group equivalent of the siloxane-based polymer satisfies the above range, the polymer matrix has an appropriate crosslink density and fully functions as a support, and the fluidity of the components contained in the photopolymer composition is improved, so that the boundary surface of the diffraction grating formed after recording does not collapse, and the initial refractive index modulation value is maintained at an excellent level even over time, minimizing the decrease in recording characteristics for optical information.

[0035] The (meth)acrylic polyol may refer to a polymer in which one or more, specifically two or more, hydroxyl groups are bonded to the main chain or side chain of a (meth)acrylate polymer. In this specification, "(meth)acrylic (based)" refers to acrylic (based) and / or methacrylic (based) unless otherwise specified, and is a term that encompasses acrylic (based), methacrylic (based), or a mixture of acrylic (based) and methacrylic (based).

[0036] The (meth)acrylic polyol may be a homopolymer of a (meth)acrylate monomer having a hydroxyl group, a copolymer of a (meth)acrylate monomer having two or more kinds of hydroxyl groups, or a copolymer of a (meth)acrylate monomer having a hydroxyl group and a (meth)acrylate monomer not having a hydroxyl group. In this specification, the term "copolymer" is a term that encompasses random copolymers, block copolymers, and graft copolymers, unless otherwise specified.

[0037] Examples of the (meth)acrylate monomer having a hydroxy group include hydroxyalkyl(meth)acrylate and hydroxyaryl(meth)acrylate, where the alkyl may be an alkyl having 1 to 30 carbon atoms and the aryl may be an aryl having 6 to 30 carbon atoms. Examples of the (meth)acrylate monomer not having a hydroxy group include alkyl(meth)acrylate and aryl(meth)acrylate monomer, where the alkyl may be an alkyl having 1 to 30 carbon atoms and the aryl may be an aryl having 6 to 30 carbon atoms.

[0038] The (meth)acrylic polyol may have a weight average molecular weight (Mw) in the range of 150,000 to 1,000,000, for example. The weight average molecular weight means a weight average molecular weight in terms of polystyrene measured by the GPC method as described above. For example, the lower limit of the weight average molecular weight may be 150,000 or more, 200,000 or more, or 250,000 or more, and the upper limit may be, for example, 900,000 or less, 850,000 or less, 800,000 or less, 750,000 or less, 700,000 or less, 650,000 or less, 600,000 or less, 550,000 or less, 500,000 or less, or 450,000 or less. When the weight average molecular weight of the (meth)acrylic polyol satisfies the above range, the polymer matrix can fully function as a support, and the decrease in the recording properties for optical information even after the passage of time can be reduced. Furthermore, the polymer matrix can be given sufficient flexibility, and the mobility of the components (e.g., photoreactive monomers or plasticizers) contained in the photopolymer composition can be improved, thereby minimizing the decrease in the recording properties for optical information.

[0039] In order to adjust the crosslinking density of the (meth)acrylic polyol by the siloxane polymer to a level advantageous for ensuring the functionality of the holographic recording medium, the hydroxyl equivalent of the (meth)acrylic polyol can be adjusted to an appropriate level.

[0040] Specifically, the hydroxyl group (-OH) equivalent of the (meth)acrylic polyol may be, for example, within the range of 500 g / equivalent to 3,000 g / equivalent. More specifically, the lower limit of the hydroxyl group (-OH) equivalent of the (meth)acrylic polyol may be 600 g / equivalent or more, 700 g / equivalent or more, 800 g / equivalent or more, 900 g / equivalent or more, 1000 g / equivalent or more, 1100 g / equivalent or more, 1200 g / equivalent or more, 1300 g / equivalent or more, 1400 g / equivalent or more, 1500 g / equivalent or more, 1600 g / equivalent or more, 1700 g / equivalent or more, or 1750 g / equivalent or more. The upper limit of the hydroxyl group (—OH) equivalent of the (meth)acrylic polyol may be 2900 g / equivalent or less, 2800 g / equivalent or less, 2700 g / equivalent or less, 2600 g / equivalent or less, 2500 g / equivalent or less, 2400 g / equivalent or less, 2300 g / equivalent or less, 2200 g / equivalent or less, 2100 g / equivalent or less, 2000 g / equivalent or less, or 1900 g / equivalent or less.

[0041] When the hydroxyl group (-OH) equivalent of the (meth)acrylic polyol satisfies the above range, the polymer matrix has an appropriate crosslink density and fully functions as a support, and the fluidity of the components contained in the photopolymer composition is improved, so that the boundary surface of the diffraction grating formed after recording does not collapse, and the initial refractive index modulation value is maintained at an excellent level even over time, minimizing the decrease in recording characteristics for optical information.

[0042] The (meth)acrylic polyol may have a glass transition temperature (Tg) in the range of, for example, -60°C to -10°C. Specifically, the lower limit of the glass transition temperature may be, for example, -55°C or more, -50°C or more, -45°C or more, -40°C or more, -35°C or more, -30°C or more, or -25°C or more, and the upper limit may be, for example, -15°C or less, -20°C or less, -25°C or less, -30°C or less, or -35°C or less. When the glass transition temperature range is satisfied, the glass transition temperature can be lowered without significantly decreasing the modulus of the polymer matrix, thereby increasing the mobility (fluidity) of other components in the photopolymer composition, and improving the moldability of the photopolymer composition. The glass transition temperature can be measured using a known method, for example, a method such as DSC (Differential Scanning Calorimetry) or DMA (dynamic mechanical analysis).

[0043] The refractive index of the (meth)acrylic polyol may be, for example, 1.40 or more and less than 1.50. Specifically, the lower limit of the refractive index of the (meth)acrylic polyol may be, for example, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more, and the upper limit may be, for example, 1.49 or less, 1.48 or less, 1.47 or less, 1.46 or less, or 1.45 or less. When the (meth)acrylic polyol has a refractive index in the above-mentioned range, it can contribute to increasing the refractive index modulation. The refractive index of the (meth)acrylic polyol is a theoretical refractive index, and can be calculated using the refractive index of the monomers used in the production of the (meth)acrylic polyol (measured using an Abbe refractometer at 25° C.) and the fraction (molar ratio) of each monomer.

[0044] The (meth)acrylic polyol and the siloxane polymer may be contained such that the molar ratio (SiH / OH) of the silane functional group (Si-H) of the siloxane polymer to the hydroxy group (-OH) of the (meth)acrylic polyol is 1.5 to 4.

[0045] The molar ratio of the silane functional groups of the siloxane polymer to the hydroxyl groups of the (meth)acrylic polyol (hereinafter, simply referred to as the SiH / OH molar ratio) can be calculated from the weight of each polymer and the number of moles of the functional groups determined from the functional group equivalent of each polymer.

[0046] Specifically, the silane functional group equivalent of the siloxane polymer is the value obtained by dividing the molecular weight (e.g., number average molecular weight) of the siloxane polymer by the number of silane functional groups per molecule, and the hydroxyl group equivalent of the (meth)acrylic polyol is the value obtained by dividing the molecular weight (e.g., weight average molecular weight) of the (meth)acrylic polyol by the number of hydroxyl functional groups per molecule. Therefore, the mole number of silane functional groups can be confirmed by dividing the weight of the siloxane polymer by the silane functional group equivalent of the siloxane polymer, and the mole number of hydroxyl groups can be confirmed by dividing the weight of the (meth)acrylic polyol by the hydroxyl group equivalent of the (meth)acrylic polyol. More specifically, taking the example of Example 1 described later, the weight (2.6 g) of the siloxane polymer used in Example 1 is divided by the silane functional group equivalent (103 g / equivalent) of the siloxane polymer used in Example 1 to calculate the number of moles of the silane functional group (0.0252 mol), and the weight (22.4 g) of the (meth)acrylic polyol used in Example 1 is divided by the hydroxyl group equivalent (1802 g / equivalent) of the (meth)acrylic polyol used in Example 1 to calculate the number of moles of the hydroxyl group (0.0124 mol). The number of moles of the silane functional group calculated in this way (0.0252 mol) is divided by the number of moles of the hydroxyl group (0.0124 mol), and it is confirmed that the molar ratio of SiH / OH is calculated to be 2.

[0047] The lower limit of the molar ratio of SiH / OH may be, for example, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, or 2.0 or more, and the upper limit may be, for example, 3.9 or less, 3.8 or less, 3.7 or less, 3.6 or less, or 3.5 or less. When the molar ratio range of SiH / OH is satisfied, the polymer matrix is ​​crosslinked at an appropriate crosslink density, improving the fluidity of components for recording (e.g., photoreactive monomers and plasticizers, etc.), thereby ensuring excellent optical recording characteristics, and even when placed in a high temperature and / or high humidity environment before and after recording, the migration or deformation of components in the photopolymer layer and the penetration of moisture, etc. into the photopolymer layer are suppressed, thereby exhibiting excellent heat resistance or moist heat resistance, etc.

[0048] The Pt catalyst may be, for example, a Karstedt catalyst. The Pt catalyst may be included in an amount of 0.01 to 2 parts by weight relative to 100 parts by weight of the (meth)acrylic polyol. Specifically, the Pt catalyst may be included in an amount of, for example, 0.02 parts by weight or more, 0.03 parts by weight or more, 0.04 parts by weight or more, 0.05 parts by weight or more, or 0.06 parts by weight or more and 1.5 parts by weight or less, 1.0 parts by weight or less, 0.5 parts by weight or less, 0.3 parts by weight or less, 0.2 parts by weight or less, 0.15 parts by weight or less, 0.14 parts by weight or less, 0.13 parts by weight or less, or 0.12 parts by weight or less relative to 100 parts by weight of the (meth)acrylic polyol. When the Pt catalyst is used in the above-mentioned content, the polymer matrix is ​​crosslinked at an appropriate crosslink density, and the desired optical recording characteristics can be exhibited.

[0049] The polymer matrix precursor may further include, in addition to the Pt-based catalyst, a rhodium-based, iridium-based, rhenium-based, molybdenum-based, iron-based, nickel-based, alkali metal or alkaline earth metal-based, Lewis acid-based, or carbene-based non-metallic catalyst, if necessary.

[0050] Meanwhile, a hologram recording medium can be recorded by irradiating an object beam and a reference beam onto a photopolymer layer formed from the photopolymer composition of the embodiment. Due to the interference length between the object beam and the reference beam, photopolymerization of the photoreactive monomer does not occur in the destructive interference region, but occurs in the reinforcement interference region. As the photoreactive monomer is continuously consumed in the reinforcement interference region, a concentration difference occurs between the photoreactive monomer in the destructive interference region and the reinforcement interference region, and as a result, the photoreactive monomer in the destructive interference region diffuses into the reinforcement interference region. A diffraction grating is generated by the refractive index modulation generated in this way.

[0051] Therefore, the photoreactive monomer may include a compound having a higher refractive index than the polymer matrix in order to realize the above-mentioned refractive index modulation. However, it is not limited that all the photoreactive monomers have a higher refractive index than the polymer matrix, and at least some of the photoreactive monomers may have a higher refractive index than the polymer matrix in order to realize a high refractive index modulation value. As an example, the photoreactive monomer may include a monomer having a refractive index of 1.50 or more, 1.51 or more, 1.52 or more, 1.53 or more, 1.54 or more, 1.55 or more, 1.56 or more, 1.57 or more, 1.58 or more, 1.59 or more, or 1.60 or more and 1.70 or less.

[0052] The photoreactive monomer may include one or more monomers selected from the group consisting of monofunctional monomers having one photoreactive functional group and polyfunctional monomers having two or more photoreactive functional groups. In this case, the photoreactive functional group may be, for example, a (meth)acryloyl group, a vinyl group, or a thiol group. More specifically, the photoreactive functional group may be a (meth)acryloyl group.

[0053] The monofunctional monomer may include, for example, one or more selected from the group consisting of benzyl (meth)acrylate (Miwon's M1182 refractive index 1.5140), benzyl 2-phenylacrylate, phenoxybenzyl (meth)acrylate (Miwon's M1122 refractive index 1.565), phenol (ethylene oxide) (meth)acrylate (phenol (EO) (meth)acrylate; Miwon's M140 refractive index 1.516), phenol (ethylene oxide) 2 (meth)acrylate (Miwon's M142 refractive index 1.510), O-phenylphenol (ethylene oxide) (meth)acrylate (Miwon's M1142 refractive index 1.577), phenylthioethyl (meth)acrylate (Miwon's M1162 refractive index 1.560) and biphenylmethyl (meth)acrylate.

[0054] The polyfunctional monomer is, for example, bisphenol A (ethylene oxide). 2~10 Di(meth)acrylate (bisphenol A (EO) 2~10(meth)acrylate; Miwon's M240 refractive index 1.537, M241 refractive index 1.529, M244 refractive index 1.545, M245 refractive index 1.537, M249 refractive index 1.542, M2100 refractive index 1.516, M2101 refractive index 1.512), bisphenol A epoxy di(meth)acrylate (Miwon's PE210 refractive index 1.557, PE2120A refractive index 1.533, PE2120B refractive index 1.534, PE2020C refractive index 1.539, PE2120S refractive index 1.556), bisfluor di(meth)acrylate (Miwon's HR6022 refractive index 1.600, HR6040 refractive index 1.600, HR60 42 refractive index 1.600), modified bisphenol fluorene di (meth) acrylate (Miwon's HR6060 refractive index 1.584, HR6100 refractive index 1.562, HR6200 refractive index 1.530), tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate (Miwon's M370 refractive index 1.508), phenol novolac epoxy (meth) acrylate (Miwon's SC6300 refractive index 1.525), and cresol novolac epoxy (meth) acrylate (Miwon's SC6400 refractive index 1.522, SC6400C refractive index 1.522).

[0055] The photopolymer composition of the embodiment may contain 50 to 300 parts by weight of the photoreactive monomer relative to 100 parts by weight of the polymer matrix. For example, the lower limit of the content of the photoreactive monomer may be 50 parts by weight or more, 70 parts by weight or more, 100 parts by weight or more, or 120 parts by weight or more, and the upper limit may be 300 parts by weight or less, 270 parts by weight or less, 250 parts by weight or less, or 220 parts by weight or less. When the above range is satisfied, excellent optical recording properties can be exhibited.

[0056] In this specification, the content of the polymer matrix means the combined content (weight) of the (meth)acrylic polyol and the siloxane polymer forming the matrix. In other words, the content of the polymer matrix means the content including the content of the polymer matrix formed by crosslinking the (meth)acrylic polyol and the siloxane polymer, and the content of the polymer matrix precursor that is not partially crosslinked.

[0057] The photopolymer composition may further include a plasticizer. When a plasticizer is added to the photopolymer composition, refractive index modulation can be more easily achieved during recording of a hologram. More specifically, the plasticizer lowers the glass transition temperature of the polymer matrix to improve the fluidity of the photoreactive monomer, and has a low refractive index and non-reactive properties and is uniformly distributed in the polymer matrix. When the non-photopolymerized photoreactive monomer moves, the plasticizer moves in the opposite direction to the movement of the non-photopolymerized photoreactive monomer, thereby contributing to refractive index modulation. The plasticizer can also contribute to improving the moldability of the photopolymer composition.

[0058] The photopolymer composition may include a fluorine-based compound as such a plasticizer.

[0059] The fluorine-based compound may have a low refractive index of 1.45 or less in order to perform the function of the plasticizer described above. Specifically, the upper limit of the refractive index may be, for example, 1.44 or less, 1.43 or less, 1.42 or less, 1.41 or less, 1.40 or less, 1.40 or less, 1.39 or less, 1.38 or less, or 1.37 or less, and the lower limit of the refractive index may be, for example, 1.30 or more, 1.31 or more, 1.32 or more, 1.33 or more, 1.34 or more, or 1.35 or more. Since a fluorine-based compound having a refractive index lower than that of the above-mentioned photoreactive monomer is used, the refractive index of the polymer matrix can be lowered, and the refractive index modulation with the photoreactive monomer can be increased.

[0060] The fluorine-based compound may contain, for example, one or more functional groups selected from the group consisting of an ether group, an ester group, and an amide group, and two or more difluoromethylene groups. More specifically, the fluorine-based compound may be, for example, a compound containing a repeating unit represented by the following chemical formula 3.

[0061] [ka]

[0062] In the above Chemical Formula 3, Multiple R 31 ~R 34 are each independently hydrogen or fluorine, and at least R 31 ~R 34 is fluorine, and m is an integer of 2 to 12.

[0063] More specifically, the fluorine-based compound may be a compound containing 1 to 3 units represented by the following chemical formula 3-1 (chemical formula 4).

[0064] [ka]

[0065] In the above Chemical Formula 3-1, R 41 ~R 44 and R 53 ~R 56 are each independently hydrogen or fluorine; R 45 ~R 52 is fluorine.

[0066] As an example, in the above formula 3-1, R 41 , R 42 , R 55 and R 56 is hydrogen and R 43 ~R 54 is fluorine.

[0067] The fluorine-based compound containing the (repeating) units represented by the formulae 3 and 3-1 may be capped with an end capping agent that is widely used in the related technical field, but is not particularly limited thereto. As an example, the end of the fluorine-based compound containing the (repeating) units represented by the formulae 3 and 3-1 may be an alkyl group or an alkyl group substituted with one or more alkoxy groups. As a non-limiting example, the end of the fluorine-based compound containing the (repeating) units represented by the formulae 3 and 3-1 may be a 2-methoxyethoxymethyl group by using 2-methoxyethoxymethyl chloride as an end capping agent.

[0068] The fluorine-based compound may have a weight average molecular weight of 300 or more. Specifically, the lower limit of the weight average molecular weight of the fluorine-based compound may be, for example, 350 or more, 400 or more, 450 or more, 500 or more, or 550 or more, and the upper limit may be, for example, 1000 or less, 900 or less, 800 or less, 700 or less, or 600 or less. When considering the refractive index modulation, compatibility with other components, and problems such as elution of the fluorine-based compound, it is preferable to satisfy the above weight average molecular weight range. At this time, the weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method as described above.

[0069] The photopolymer composition of the embodiment may contain 20 to 200 parts by weight of the fluorine-based compound relative to 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the fluorine-based compound may be, for example, 25 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, or 80 parts by weight or more, and the upper limit may be, for example, 190 parts by weight or less, 180 parts by weight or less, 170 parts by weight or less, 160 parts by weight or less, or 150 parts by weight or less. When the range is satisfied, there is no problem such as poor compatibility with the components contained in the photopolymer composition, some of the fluorine-based compound is eluted on the surface of the photopolymer layer, and haze is deteriorated, and a fluorine-based compound having a sufficiently low refractive index can show a large refractive index modulation value after recording, which is advantageous for ensuring excellent optical recording properties.

[0070] On the other hand, when the elemental composition ratio measured on the surface of a photopolymer layer formed from a photopolymer composition containing a fluorine-based compound satisfies a specific ratio, the photopolymer layer can exhibit not only excellent optical recording properties but also excellent stability over time even at high temperatures.

[0071] Specifically, the element ratio of the photopolymer layer surface can be confirmed by using photoelectron spectroscopy, which is called X-ray photoelectron spectroscopy (XPS) or Electron Spectroscopy for Chemical Analysis (ESCA). According to the photoelectron spectroscopy described in the test example described later, after qualitative analysis of elements found on the surface of the sample to be analyzed by a survey scan, a narrow scan can be performed for each element found to measure the element ratio. The element ratio of the photopolymer layer in this specification may be understood as the element ratio of the photopolymer layer before recording, or the element ratio of the photopolymer layer after recording. The element ratio of the photopolymer layer before recording and the element ratio of the photopolymer layer after recording may be the same within the experimental error range, but may be different from each other in some examples. In other words, even if the element ratio of the photopolymer layer before recording and the element ratio after recording are different from each other beyond the error range, the holographic recording medium manufactured from the photopolymer composition of the embodiment can exhibit the intended effect as long as the element ratio before or after recording is within the above-mentioned range.

[0072] The atomic ratio of carbon on the surface of a photopolymer layer formed from the photopolymer composition of one embodiment of the present invention may be 50 atomic % or more, 51 atomic % or more, 52 atomic % or more, 53 atomic % or more, or 54 atomic % or more, and may be 70 atomic % or less, 69 atomic % or less, or 68 atomic % or less.

[0073] The atomic ratio of nitrogen at the surface of the photopolymer layer may be 0.01 atomic % or more, 0.05 atomic % or more, 0.10 atomic % or more, or 0.20 atomic % or more, and may be 2 atomic % or less, 1.8 atomic % or less, 1.6 atomic % or less, 1.4 atomic % or less, or 1.2 atomic % or less.

[0074] The atomic ratio of oxygen on the surface of the photopolymer layer may be 15 atomic % or more, 16 atomic % or more, or 17 atomic % or more, and may be 30 atomic % or less, 29 atomic % or less, 28 atomic % or less, 27 atomic % or less, or 26 atomic % or less.

[0075] The atomic ratio of fluorine in the surface of the photopolymer layer may be 3 atomic % or more, or 4 atomic % or more, and may be 12 atomic % or less, 11 atomic % or less, or 10 atomic % or less.

[0076] The atomic ratio of silicon in the surface of the photopolymer layer may be 3 atomic % or more, 4 atomic % or more, or 4.5 atomic % or more, and may be 15 atomic % or less.

[0077] The elemental ratios of carbon, nitrogen, oxygen, fluorine and silicon are percentages (atomic %) relative to the total amount of carbon, nitrogen, oxygen, fluorine and silicon atoms confirmed by photoelectron spectroscopy on the surface of the photopolymer layer.

[0078] The photopolymer layer exhibits the above-mentioned elemental composition ratio, and thus exhibits excellent optical recording characteristics and excellent stability over time at high temperatures. In particular, if the fluorine element ratio is less than the above range, the optical recording characteristics may be deteriorated, and if the fluorine element ratio exceeds the above range, the stability over time may be deteriorated due to vulnerability to moisture. In addition, if the silicon element ratio is less than the above range, the haze may be increased due to vulnerability to heat, and if the silicon element ratio exceeds the above range, the optical recording characteristics may be significantly deteriorated.

[0079] The majority of the components of the photopolymer layer are the polymer matrix (the polymer matrix may be included in a precursor form capable of forming the polymer matrix), the photoreactive monomer, and the fluorine-based compound, which is a plasticizer added as required. Therefore, the elemental composition ratio of the surface of the photopolymer layer can be controlled by the blending ratio of the polymer matrix, the photoreactive monomer, and the fluorine-based compound contained in the photopolymer composition. In order to provide a photopolymer layer that satisfies the above-mentioned elemental composition ratio, the photopolymer composition of the embodiment can contain 17% by weight to 38% by weight of the polymer matrix, 36% by weight to 58% by weight of the photoreactive monomer, and 17% by weight to 38% by weight of the fluorine-based compound, based on the total weight of the polymer matrix, the photoreactive monomer, and the fluorine-based compound.

[0080] More specifically, the polymer matrix may be contained, for example, at 17% by weight or more, 18% by weight or more, 19% by weight or more, or 20% by weight or more, and 38% by weight or less, 37% by weight or less, or 36% by weight or less. The photoreactive monomer may be contained, for example, at 36% by weight or more, 37% by weight or more, or 38% by weight or more, and 58% by weight or less, 55% by weight or less, or 53% by weight or less. The fluorine-based compound may be contained, for example, at 17% by weight or more, 18% by weight or more, 19% by weight or more, or 20% by weight or more, and 38% by weight or less, 35% by weight or less, 33% by weight or less, or 32% by weight or less. A photopolymer layer satisfying the above-mentioned element composition ratio within such a range can be provided.

[0081] The photopolymer composition of one embodiment includes a photoinitiator system, which can mean a photoinitiator that allows polymerization to be initiated by light, or can mean a combination of a photosensitizer and a coinitiator.

[0082] The photopolymer composition of the embodiment may include a photosensitizer and a coinitiator as a photoinitiator system, and the photosensitizer may be a photosensitive dye.

[0083] Specifically, examples of the light-sensitive dye include silicon rhodamine compounds, sulfonium derivatives of ceramidonin, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose bengal, thionine, basic yellow, pinacyanol chloride, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, Quinaldine Red, crystal violet, brilliant green, and the like. One or more selected from the group consisting of fluorescein red, astrazon orange G, darrow red, pyronin Y, basic red 29, pyrylium iodide, safranin O, cyanine, methylene blue, azure A, and BODIPY may be used.

[0084] As an example, the photosensitive dye may be a silicon rhodamine compound represented by the following formula 4 (Formula 5).

[0085] [ka] In the above Chemical Formula 4, R21 ~R 29 each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, d and e each independently represent an integer of 0 to 3; f is an integer from 0 to 5; An - is an anion.

[0086] The above-mentioned "substituted or unsubstituted" means that hydrogen or carbon is substituted with another element, and hydrogen may be substituted with a halogen, a hydroxyl group, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, and carbon (-CH2-) may be substituted with -O- or -CO-.

[0087] In the above formula 4, R 21 ~R 28 may each independently be a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. 21 ~R 28 may each independently be an alkyl group having 1 to 6 carbon atoms. More specifically, in the above Chemical Formula 4, R 21 ~R 28 may be a methyl group.

[0088] In the above Chemical Formula 4, d and e may each independently be an integer of 0 to 2, an integer of 0 to 1, or 0.

[0089] In the above Chemical Formula 4, f may be an integer of 0 to 5, an integer of 0 to 4, an integer of 0 to 3, an integer of 0 to 2, or an integer of 1 to 2.

[0090] In the above formula 4, R 29 may be a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. 29may be an alkoxy group having 1 to 6 carbon atoms. More specifically, in the above Chemical Formula 4, R 29 may be a methoxy group.

[0091] In the above formula 4, an anion (An - ) may be a halide anion, a cyano anion, a sulfonate anion, an alkoxy anion having 1 to 30 carbon atoms, a substituted or unsubstituted alkylsulfonate anion having 1 to 30 carbon atoms, a substituted or unsubstituted aromatic sulfonate anion having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic borate anion having 6 to 30 carbon atoms.

[0092] Specifically, in the above Chemical Formula 4, - ) may be a substituted or unsubstituted alkylsulfonate anion having 1 to 30 carbon atoms, a substituted or unsubstituted aromatic sulfonate anion having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic borate anion having 6 to 30 carbon atoms.

[0093] More specifically, in the above Chemical Formula 4, an anion (An - ) may be an alkylsulfonate anion having 2 to 15 carbon atoms in which one or more hydrogen atoms are substituted or unsubstituted with fluorine, an alkylsulfonate anion having 6 to 30 carbon atoms in which one or more carbon atoms are substituted or unsubstituted with -O- or -CO- (Chemical formula 6), a phenylsulfonate anion substituted or unsubstituted with methyl, or a substituted or unsubstituted tetraarylborate anion. - ) may be a dodecylsulfonate anion, a perfluorobutylsulfonate anion, a phenylsulfonate anion, a methylphenylsulfonate anion, or a tetraphenylborate anion.

[0094] [ka]

[0095] The photopolymer composition of the embodiment may contain the photosensitive dye in a range of 0.01 to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the photosensitive dye may be, for example, 0.02 parts by weight or more, 0.03 parts by weight or more, or 0.05 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous to show an appropriate polymerization reaction speed and ensure the desired optical recording characteristics.

[0096] The coinitiator can include an electron donor, an electron acceptor, or a mixture thereof.

[0097] As an example, the photopolymer composition may include an electron donor as a coinitiator. In particular, the photopolymer composition may provide a holographic recording medium having excellent stability over time by using an electron donor that exhibits a specific reaction energy with the above-mentioned photosensitive dye.

[0098] Specifically, the electron donor reacts with the photosensitive dye excited to a triplet state by irradiation with light as shown in the following reaction formula 1 (chemical formula 7) to participate in the photopolymerization initiation reaction.

[0099] [ka]

[0100] In this case, if an electron donor having a reaction energy of -25 kJ / mol to 0 kJ / mol with a photosensitive dye excited to a triplet state is used, the reaction does not initiate even at room temperature or high temperatures before light irradiation, demonstrating excellent stability over time, while when irradiated with light, a photoinitiated reaction occurs sensitively, demonstrating excellent optical recording characteristics.

[0101] More specifically, the electron donor may have a reaction energy with the photosensitive dye excited to the triplet state of -25 kJ / mol or more, -20 kJ / mol or more, -15 kJ / mol or more, -14 kJ / mol or more, -13 kJ / mol or more, -12 kJ / mol or more, -11 kJ / mol or more, -10 kJ / mol or more, -9 kJ / mol or more, or -8.5 kJ / mol or more, and 0 kJ / mol or less, -3 kJ / mol or less, or -5 kJ / mol or less. The reaction energy may be measured by referring to the measurement method described in detail in the test examples below.

[0102] The photopolymer composition of the embodiment may further include an electron acceptor as necessary, together with the electron donor, as described below. When the electron acceptor receives electrons during the oxidation-reduction reaction of the photoinitiator system and includes an electron acceptor, the total energy E2 of the photoinitiator system reaction becomes negative. However, the inventors' research has shown that even if the total energy of the photoinitiator system reaction changes due to the inclusion of an electron acceptor, excellent stability over time can be ensured only when the reaction energy of the photosensitive dye and the electron donor is within the above-mentioned range.

[0103] The electron donor may include, for example, a borate anion represented by the following chemical formula 5:

[0104] [ka]

[0105] In the above Chemical Formula 5, X 1 ~X 4 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, and X 1 ~X 4 At least one of is not an aryl group.

[0106] When the alkyl group having 1 to 20 carbon atoms, the alkenyl group having 2 to 20 carbon atoms, the aryl group having 6 to 30 carbon atoms, the arylalkyl group having 7 to 30 carbon atoms, the alkylaryl group having 7 to 30 carbon atoms or the allyl group is substituted, it may be substituted with one or more selected from the group consisting of halogen, a vinyl group, a haloalkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms.

[0107] Specifically, X 1 ~X 3 each independently represents a phenyl, methylphenyl, naphthyl, or methylnaphthyl group, which may be substituted or unsubstituted by one or more substituents selected from the group consisting of a halogen, a vinyl group, a trifluoromethyl group, and a methoxy group; 4 may be a linear alkyl group having 1 to 12 carbon atoms.

[0108] The cation bonded to the borate anion does not absorb light and may be one or more cations selected from the group consisting of alkali metal cations, quaternary ammonium cations, and nitrogen-containing heterocyclic cations.

[0109] The alkali metal cation may be, for example, one or more selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium.

[0110] The quaternary ammonium cation may be an ammonium cation in which the nitrogen (N) is substituted with four substituents, or a cyclic ammonium cation in which two substituents substituted on the nitrogen are linked to each other, or a mixture thereof.

[0111] The nitrogen-containing heterocyclic cation may be a heteroaromatic ring cation containing one or more nitrogens. Examples of such heteroaromatic ring cations include pyrrole, pyrazole, imidazole, or pyridine cations, the hydrogens of which may be substituted or unsubstituted.

[0112] For example, when the above-mentioned silicon rhodamine compound is used as the photosensitive dye, the electron donor may include one or more selected from the group consisting of borate anions represented by the following formulas 5-1 (Chemical formula 9) and 5-2 (Chemical formula 10). The combination of the photosensitive dye and the borate anion exhibits a reaction energy in the above-mentioned range, ensuring excellent stability over time, while at the same time exhibiting excellent sensitivity, and exhibiting excellent characteristics in the various physical properties of the holographic recording medium, such as diffraction efficiency, refractive index modulation value, image reproducibility, and angle selectivity.

[0113] [ka]

[0114] In the above Chemical Formula 5-1, R 102 are each independently methyl or chlorine; R 103 are each independently hydrogen, methyl or chlorine, and adjacent R 102 is chlorine when is methyl, X 4’ is a straight-chain alkyl group having 1 to 12 carbon atoms.

[0115] [ka]

[0116] In the above Chemical Formula 5-2, R 106 are each independently hydrogen, methyl or halogen; X 4” is a straight-chain alkyl group having 1 to 12 carbon atoms.

[0117] In the above Chemical Formula 5-2, R 106 are each independently hydrogen, methyl or halogen, and at least one may be halogen.

[0118] In the formula 5-2, the halogen may be fluorine or chlorine. In particular, chlorine has better heat resistance and can ensure good stability over time not only at room temperature but also at high temperatures.

[0119] In addition, when the above-mentioned silicon rhodamine compound is used as the photosensitive dye, the cation bonded to the borate anion may include at least one selected from the group consisting of the cation (quaternary ammonium cation) represented by the following chemical formula 5-3 (chemical formula 11) and the cation (nitrogen-containing heterocyclic cation) represented by the following chemical formula 5-4. Such a combination of the photosensitive dye with the borate anion and cation exhibits a reaction energy in the above-mentioned range, ensuring excellent stability over time, while at the same time exhibiting excellent sensitivity, and exhibiting excellent characteristics in the various physical properties of the holographic recording medium, such as diffraction efficiency, refractive index modulation value, image reproducibility, and angle selectivity.

[0120] [ka]

[0121] In the above Chemical Formula 5-3, Y 1 ~Y 4 the two substituents may or may not be linked to each other to form an aliphatic ring having 4 to 10 carbon atoms, Y does not form an aliphatic ring 1 ~Y 4 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond (for example, -CH2CH2-O-CO-CH2CH2CH3, etc.), Y 1 ~Y4 are excluded.

[0122] In the above Chemical Formula 5-3, Y 1 ~Y 4 When all of the substituents are methyl groups, or when two or more of the substituents are alkyl groups having 16 or more carbon atoms, the electron donor does not dissolve well in the photopolymer composition, and the desired optical recording properties may not be exhibited.

[0123] Specifically, Y 1 ~Y 4 The two substituents can be linked together to form a piperidine or pyrrolidine.

[0124] The above Y 1 ~Y 4 Among these, the substituents not forming an aliphatic ring may each independently be a linear alkyl group having 1 to 32 carbon atoms, a phenyl group, a benzyl group, or -CH2CH2-O-CO-CH2CH2CH3. 1 ~Y 4 Among these, the substituents not forming an aliphatic ring may each independently be a methyl group, a butyl group, a hexadecyl group, a hentriacontyl group, a phenyl group, or a benzyl group.

[0125] [ka]

[0126] In the above Chemical Formula 5-4 (Chemical Formula 12), R 107 , R 109 and R 110 are each independently a hydrogen atom, an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond (for example, -CH2CH2-O-CO-CH2CH2CH3, etc.), R 108 and R 111are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond (for example, -CH2CH2-O-CO-CH2CH2CH3, etc.).

[0127] Specifically, R 107 , R 109 and R 110 may each independently be hydrogen or an aryl group having 6 to 30 carbon atoms. More specifically, R 107 , R 109 and R 110 may each independently be hydrogen or a phenyl group.

[0128] Specifically, the R 108 and R 111 may be a linear alkyl group having 1 to 40 carbon atoms or an arylalkyl group having 6 to 40 carbon atoms. 108 and R 111 may be a hexadecyl group or a benzyl group.

[0129] The cation bound to the borate anion is a cation represented by the chemical formulas 5-3 and 5-4, and may include at least one selected from the group consisting of, for example, tetrabutylammonium cation, hexadecyldimethylbenzylammonium cation, hentriacontyldimethylbenzylammonium cation, hexadecylbenzylpiperidinium cation, hexadecylbenzylpyrrolidinium cation, 1-hexadecyl-3-benzylimidazolium cation, and 1,3-dihexadecyl-2-phenylimidazolium cation.

[0130] However, the cations combined with the borate anion are not limited to the above cations, and as long as they show low solubility when contained alone but show appropriate solubility when mixed with the above cations, some of the above cations may be substituted with other cations known in the related technical field. As a non-limiting example, some of the above cations may be substituted with 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium, etc.

[0131] The photopolymer composition may contain the electron donor in the range of 0.05 parts by weight to 10 parts by weight relative to 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the electron donor may be, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous to ensure the desired optical recording characteristics by exhibiting an appropriate polymerization reaction rate.

[0132] As an example, the photopolymer composition can include an electron acceptor as a coinitiator, which can include, for example, an onium salt, such as a sulfonium salt, an iodonium salt, or the like; a triazine compound, such as a tris(trihalomethyl)triazine, a substituted bis(trihalomethyl)triazine, or the like; or a mixture thereof.

[0133] Specifically, the electron acceptor may include (4-(octyloxy)phenyl)(phenyl)iodonium salt as an iodonium salt, or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine as a triazine compound.

[0134] As the electron acceptor, for example, commercially available H-Nu254 (Spectra) or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine (TCI) can be used.

[0135] Among them, a triazine compound can be used as the electron acceptor. When a triazine compound is used as the electron acceptor, the temporal stability of the holographic recording medium at high temperatures before recording can be further improved.

[0136] The photopolymer composition may contain the electron acceptor in the range of 0.025 parts by weight to 2 parts by weight relative to 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the coinitiator may be, for example, 0.025 parts by weight or more, 0.027 parts by weight or more, 0.030 parts by weight or more, or 0.031 parts by weight or more, and the upper limit may be, for example, 2 parts by weight or less, 1.9 parts by weight or less, 1.7 parts by weight or less, 1.5 parts by weight or less, or 1 part by weight or less. When the above range is satisfied, a holographic recording medium having not only excellent optical recording properties but also low haze can be provided.

[0137] The photoinitiator system may contain an additional photoinitiator to remove the color of the photosensitive dye and to react all of the unreacted photoreactive monomers after irradiation with light for recording. Examples of the photoinitiator include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, thioxanthone derivatives, amine derivatives, diazonium salts, sulfonium salts, iodonium salts, sulfonic acid esters, imidosulfonates, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η6-benzene)(η5-cyclopentadienyl)iron(II), benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosylphthalimide, and mixtures thereof.More specifically, the photoinitiator may be 1,3-di(t-butyldioxycarbonyl)benzophenone, 3,3',4,4''-tetrakis(t-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-mercapto benzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one (product name: Irgacure651 / manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure369 / manufacturer: BASF), bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium (product name: Irgacure784 / manufacturer: BASF), Ebecryl P-115 (manufacturer: SK entis), Cyracure UVI-6970, Cyracure Examples include, but are not limited to, UVI-6974, Cyracure UVI-6990 (manufactured by Dow Chemical Co. in USA), Irgacure 264, Irgacure 250 (manufactured by BASF), CIT-1682 (manufactured by Nippon Soda), or mixtures thereof.

[0138] The photopolymer composition may contain the photoinitiator in a range of 0.05 parts by weight to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the photoinitiator may be, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above range is satisfied, after optical information is recorded in the photopolymer layer, the reaction of the photoreactive monomer can be effectively terminated and the color of the photosensitive dye can be decolorized to provide a transparent holographic recording medium.

[0139] The photopolymer composition of the embodiment may further include additives such as a surfactant or an antifoaming agent.

[0140] The photopolymer composition may contain, as a surfactant, a silicone-based surfactant, a fluorosurfactant, or a mixture thereof.

[0141] Examples of the silicone surfactant that can be used include BYK-077, BYK-085, BYK-300, BYK-301, BYK-302, BYK-306, BYK-307, BYK-310, BYK-320, BYK-322, BYK-323, BYK-325, BYK-330, BYK-331, BYK-333, BYK-335, BYK-341v344, BYK-345v346, BYK-348, BYK-354, BYK355, BYK-356, BYK-358, BYK-361, BYK-370, BYK-371, BYK-375, BYK-380, BYK-390, and BYK-3550 manufactured by BYK Chemie. Examples of the fluorine-based surfactant include F-114, F-177, F-410, F-411, F-450, F-493, F-494, F-443, F-444, F-445, F-446, F-470, F-471, F-472SF, F-474, F-475, F-477, F-478, F-479, F-480SF, F-482, F-483, F-484, F-485, F-486, F-487, F-488, F-489, F-490SF, F-491, F-492SF, F-493, F-494, F-495, F-497, F-498, F-499, F-480SF, F-482, F-483, F-484, F-485, F-486, F-487, F-488, F-489 ...9, F-489, F-490, F -486, F-487, F-172D, MCF-350SF, TF-1025SF, TF-1117SF, TF-1026SF, TF-1128, TF-1127, TF1129, TF-1126, TF-1130, TF-1116SF, TF-1131, TF1132, TF1027SF, TF-1441, TF-1442, etc. can be used.

[0142] If the photopolymer composition of the embodiment includes a surfactant, the surfactant may be 0.01 parts by weight or more, 0.02 parts by weight or more, 0.03 parts by weight or more, or 0.05 parts by weight or more, and 5 parts by weight or less, or 3 parts by weight or less, based on 100 parts by weight of the polymer matrix. When the surfactant satisfies the above range, the photopolymer layer can be provided with excellent adhesion and releasability, and excellent optical recording properties can be maintained.

[0143] The photopolymer composition of the embodiment may include a silicone-based reactive additive as an antifoaming agent. The silicone-based reactive additive may be a commercially available product such as Tego Rad 2500. The content of the antifoaming agent may be appropriately adjusted to a level that does not interfere with the function of the holographic recording medium.

[0144] The photopolymer composition of the embodiment may include a solvent.

[0145] The solvent may be an organic solvent, and may be, for example, one or more organic solvents selected from the group consisting of ketones, alcohols, acetates, and ethers, but is not limited thereto.Specific examples of such organic solvents include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or isobutyl ketone; alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, or t-butanol; acetates such as ethyl acetate, i-propyl acetate, or polyethylene glycol monomethyl ether acetate; and ethers such as tetrahydrofuran or propylene glycol monomethyl ether.

[0146] The organic solvent may be added when the components to be contained in the photopolymer composition are mixed, or each component may be added in a dispersed or mixed state in the organic solvent and then contained in the photopolymer composition.

[0147] The photopolymer composition may contain a solvent so that the solids concentration is 1% by weight to 90% by weight. Specifically, the photopolymer composition may contain a solvent so that the solids concentration is 20% by weight or more, 25% by weight or more, or 30% by weight or more, and 50% by weight or less, 45% by weight or less, or 40% by weight or less. Within such a range, the photopolymer composition may exhibit suitable flowability, form a coating film without defects such as stripes, and form a photopolymer layer exhibiting desired physical properties and surface characteristics without defects during the drying and curing process.

[0148] Meanwhile, according to another embodiment of the present invention, there is provided a holographic recording medium comprising a photopolymer layer formed from the photopolymer composition.

[0149] The photopolymer composition has been described in detail above, and so a detailed description thereof will be omitted here.

[0150] The holographic recording medium according to the other embodiment has excellent refractive index modulation, diffraction efficiency, and driving reliability despite having a thin photopolymer layer.

[0151] The thickness of the photopolymer layer may be, for example, in the range of 5.0 μm to 40.0 μm. Specifically, the lower limit of the thickness of the photopolymer layer may be, for example, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. And the upper limit of the thickness may be, for example, 35 μm or less, 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, or 18 μm or less.

[0152] The holographic recording medium according to the other embodiment may further include a substrate on at least one surface of the photopolymer layer. The type of substrate is not particularly limited, and any substrate known in the related technical field may be used. For example, substrates such as glass, polyethylene terephthalate (PET), triacetyl cellulose (TAC), polycarbonate (PC), and cycloolefin polymer (COP) may be used.

[0153] The holographic recording medium of the other embodiment may have high diffraction efficiency. As an example, the holographic recording medium may have a diffraction efficiency of 80% or more when a notch filter hologram is recorded. In this case, the thickness of the photopolymer layer may be, for example, 5 μm to 30 μm. Specifically, the diffraction efficiency when the notch filter hologram is recorded may be 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, or 98% or more. In this way, the holographic recording medium of the other embodiment may achieve excellent diffraction efficiency even if it includes a thin photopolymer layer. The diffraction efficiency can be measured by the method described in the test example described later.

[0154] The holographic recording medium according to the embodiment may exhibit excellent stability over time not only at room temperature but also at high temperatures. For example, the holographic recording medium may have a minimum transmittance change of 20% or less as calculated by the following Equation 1:

[0155]

number

[0156] In the above formula 1, T0 is the minimum transmittance measured in the wavelength range of 300 nm to 1,200 nm using a UV-Vis spectrometer for a sample on which a notch filter hologram is recorded after storing the unrecorded holographic recording medium in a dark room at a temperature of 20°C to 25°C and a relative humidity of 40% to 50%, T1 is the minimum transmittance measured as described above for a sample on which a notch filter hologram is recorded after storing the unrecorded hologram recording medium in a dark room at a temperature of 60° C. and a relative humidity of 40% to 50% for 100 hours.

[0157] The change in minimum transmittance calculated by the above formula 1 is an index for evaluating the stability over time of the holographic recording medium before recording, particularly at high temperatures (60°C), and the holographic recording medium of the other embodiment can exhibit the originally intended level of optical recording characteristics even when left at high temperatures for 100 hours before recording.

[0158] Specifically, the holographic recording medium of the other embodiment may have a change in minimum transmittance (ΔT) calculated by the above formula 1 of 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less. The lower limit of the change in minimum transmittance (ΔT) calculated by the above formula 1 is not particularly limited, and may be 0% or more.

[0159] On the other hand, since a holographic recording medium uses a mixture of a component having a low refractive index and a component having a high refractive index for recording optical characteristics, the holographic recording medium is likely to have opaque characteristics due to the compatibility between the components. However, the holographic recording medium of the other embodiment includes a photopolymer layer that satisfies a specific elemental composition ratio or includes a predetermined content of an electron acceptor, thereby exhibiting excellent optical recording characteristics and highly transparent optical characteristics.

[0160] As an example, the haze of the holographic recording medium may be 2.5% or less. The upper limit of the haze may be, for example, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% or less, 2.0% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, or 1.0% or less. The lower limit of the haze is not particularly limited and may be 0% or more. The haze may be, for example, a value measured using a haze measuring instrument (HM-150, A light source, Murakami Co., Ltd.) in accordance with JIS K 7136 after preparing a test piece of 5 cm x 5 cm from a holographic recording medium in which a diffraction grating is recorded.

[0161] The holographic recording medium of the other embodiment is not limited to this, but may be one in which a reflection type hologram or a transmission type hologram is recorded.

[0162] Meanwhile, according to yet another embodiment of the present invention, there is provided a method for manufacturing a holographic recording medium, comprising the steps of: forming a photopolymer layer by applying a photopolymer composition comprising: a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer having a silane functional group and a (meth)acrylic polyol; a photoreactive monomer; and a photoinitiator system including a photosensitive dye and a coinitiator, the co-initiator including an electron donor having a reaction energy of -25 kJ / mol to 0 kJ / mol with the photosensitive dye excited to a triplet state; and irradiating a predetermined region of the photopolymer layer with a coherent laser to selectively polymerize the photoreactive monomer contained in the photopolymer layer to record optical information.

[0163] The photopolymer composition has been described in detail above, and therefore will not be described in detail here.

[0164] In the step of forming the photopolymer layer, a photopolymer composition having the above-mentioned configuration can be prepared first. When preparing the photopolymer composition, a commonly known mixer, stirrer, mixer, etc. can be used to mix the components without any restrictions. The mixing process may be performed at a temperature in the range of 0°C to 100°C, 10°C to 80°C, or 20°C to 60°C.

[0165] In the step of forming the photopolymer layer, a prepared photopolymer composition may be applied to form a coating film formed from the photopolymer composition. The coating film may be dried at a temperature of 50° C. or more, 55° C. or more, 60° C. or more, 65° C. or more, or 70° C. or more and 120° C. or less, 110° C. or less, 100° C. or less, or 90° C. or less. Through this process, a hydrosilylation reaction between the hydroxyl group of the (meth)acrylic polyol that remains unreacted and the silane functional group of the siloxane polymer is induced, thereby achieving a desired crosslink density.

[0166] The photopolymer layer manufactured by the step of forming the photopolymer layer may have a photoreactive monomer, a photoinitiator system, and additives added as needed uniformly dispersed within a crosslinked polymer matrix.

[0167] Thereafter, when a coherent laser is irradiated onto the photopolymer layer in the step of recording optical information, polymerization of the photoreactive monomer occurs in the area where constructive interference occurs, forming a photopolymer, while polymerization of the photoreactive monomer does not occur or is suppressed in the area where destructive interference occurs, resulting in the existence of photoreactive monomer. The unreacted photoreactive monomer diffuses into the photopolymer side where the concentration of the photoreactive monomer is low, causing refractive index modulation, which generates a diffraction grating. As a result, a hologram, i.e., optical information, is recorded in the photopolymer layer having the diffraction grating.

[0168] In yet another embodiment of the method for manufacturing a holographic recording medium, after the step of recording optical information, the method may further include a step of photobleaching by irradiating light to the entire photopolymer layer on which the optical information is recorded.

[0169] In the photobleaching step, the photopolymer layer on which the optical information is recorded is irradiated with ultraviolet light to terminate the reaction of the photoreactive monomer remaining in the photopolymer layer, thereby removing the color of the photosensitive dye. For example, in the photobleaching step, ultraviolet light (UVA) in the range of 320 nm to 400 nm is irradiated to terminate the reaction of the photoreactive monomer, thereby removing the color of the photosensitive dye.

[0170] Meanwhile, according to still another embodiment of the present invention, there is provided an optical element including the holographic recording medium.

[0171] Specific examples of the optical element include smart devices such as mobile devices, parts of wearable displays, vehicle accessories (e.g., head up displays), holographic fingerprint recognition systems, holographic optical elements having the functions of optical lenses, mirrors, deflection mirrors, filters, diffusion screens, diffraction members, light guides, waveguides, projection screens and / or masks, media and light diffusion plates in optical memory systems, optical wavelength splitters, reflective and transmissive color filters, etc.

[0172] An example of an optical element including the holographic recording medium is a holographic display device, which includes a light source unit, an input unit, an optical system, and a display unit.

[0173] Specifically, the light source unit is a part that irradiates a laser beam used to provide, record and reproduce three-dimensional image information of an object in the input unit and the display unit.

[0174] The input unit is a unit that inputs 3D image information of an object to be recorded on the display unit in advance. Specifically, the input unit can input 3D information of an object such as spatial light intensity and phase to an electrically addressed liquid crystal SLM, and can use an input beam at this time.

[0175] The optical system may be composed of a mirror, a polarizer, a beam splitter, a beam shutter, a lens, etc. The optical system can distribute a laser beam emitted from a light source unit into an input beam sent to an input unit, a recording beam sent to a display unit, a reference beam, an erase beam, a read beam, etc.

[0176] The display unit receives 3D image information of an object from an input unit, records it on a hologram plate consisting of an optically addressed SLM, and reproduces a 3D image of the object. At this time, the 3D image information of the object can be recorded by interference between an input beam and a reference beam. The 3D image information of the object recorded on the hologram plate can be reproduced as a 3D image by a diffraction pattern generated by a read beam, and an erase beam can be used to quickly remove the formed diffraction pattern. Meanwhile, the hologram plate can be moved between a position for inputting a 3D image and a position for reproducing the 3D image. Effect of the Invention

[0177] The photopolymer composition according to one embodiment of the present invention includes an electron donor having a reaction energy of -25 kJ / mol to 0 kJ / mol with a photosensitive dye excited to a triplet state. This not only provides excellent optical recording properties such as diffraction efficiency, which is a basic physical property of a holographic recording medium, but also provides excellent high-temperature aging stability before recording optical information. Even if stored at room temperature to high temperatures for a long period of time, the intended optical recording properties can be maintained, and a holographic recording medium capable of reproducing a clear image without problems such as halos can be provided. [Brief description of the drawings]

[0178] [Figure 1] 1 is a schematic diagram showing the setup of a recording device for holographic recording. Specifically, Fig. 1 shows a process in which a laser of a predetermined wavelength is irradiated from a light source 10, and then passes through mirrors 20, 20', an iris 30, a spatial filter 40, an iris 30', a focusing lens 50, and a polarized beam splitter (PBS) 60, and is then irradiated onto a PP (holographic recording medium) 80 located on one side of a mirror 70. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0179] The functions and effects of the present invention will be described in more detail below through specific examples of the present invention, which are presented as examples of the present invention and are not intended to limit the scope of the invention in any way.

[0180] In the following Production Examples, Examples, Comparative Examples, and the like, the contents of raw materials and the like refer to the contents on a solid basis unless otherwise specified.

[0181] (Production Example 1: Production of (meth)acrylic polyol) In a 2L jacketed reactor, 132g of butyl acrylate, 420g of ethyl acrylate, and 48g of hydroxybutyl acrylate were added and diluted with 1200g of ethyl acetate. The reaction temperature was set to 60°C to 70°C, and stirring was continued for about 30 minutes to 1 hour. 0.42g of n-dodecyl mercaptan (n-DDM) was added and stirring was continued for about 30 minutes. Then, 0.24g of polymerization initiator AIBN was added, and polymerization was continued for more than 4 hours at the reaction temperature until the residual acrylate content was less than 1%, and a (meth)acrylate copolymer with hydroxyl groups located in the branched chain (weight average molecular weight about 300,000, OH equivalent about 1802g / equivalent) was produced.

[0182] (Production Example 2: Production of Fluorine-Based Compounds) In a 1000 mL flask, 20.51 g of 2,2'-(oxybis((1,1,2,2-tetrafluoroethane-2,1-diyl)oxy))bis(2,2-difluoroethan-1-ol) was placed, dissolved in 500 g of tetrahydrofuran, and 4.40 g of sodium hydroxide (60% dispersion in mineral oil) was carefully added several times while stirring at 0° C. After stirring for 20 minutes at 0° C., 12.50 mL of 2-methoxyethoxymethyl chloride was slowly added dropwise. After 1H NMR confirmed that all reactants had been consumed, work-up with dichloromethane gave 29g of liquid product with a purity of over 95% in a yield of 98%. The weight-average molecular weight of the produced fluorine-based compound was 586, and the refractive index measured by Abbe refractometer was 1.361.

[0183] (Example 1: Production of photopolymer composition and holographic recording medium) (1) Preparation of photopolymer composition Trimethylsilyl terminated poly(methylhydrosiloxane) (manufactured by Sigma-Aldrich, number average molecular weight: about 390, SiH equivalent: about 103 g / equivalent) as a siloxane polymer and the (meth)acrylic polyol produced in Production Example 1 were mixed first. The content of the (meth)acrylic polyol was 22.4 g, and the siloxane polymer was added so that the molar ratio of SiH / OH was 2. In Example 1, 2.6 g of the siloxane polymer was added. Then, 52g of HR6042 (Miwon, refractive index 1.60) as a photoreactive monomer, 0.2g of a compound represented by the following chemical formula a (Chemical formula 13) as a photosensitive dye, 0.8g of hexadecyldimethylbenzylammonium tri(m-chloro-p-methylphenyl)butylborate as a coinitiator, 0.05g of 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine (TCI), 0.9g of Irgacure369 as a photoinitiator, 23g of the fluorine-based compound prepared in Preparation Example 2 as a plasticizer, and 190g of methyl isobutyl ketone (MIBK) as a solvent were added, and the mixture was stirred for about 30 minutes in a Paste mixer while blocking light. Then, 0.014g of Karstedt (Pt-based) catalyst was added for matrix crosslinking to prepare a photopolymer composition.

[0184] [ka]

[0185] (2) Manufacturing of holographic recording media The photopolymer composition was coated to a predetermined thickness on a 60 μm thick TAC substrate using a Mayer bar and dried for 10 minutes at 80° C. After drying, the thickness of the photopolymer layer was about 15 μm.

[0186] (Examples 2 to 10 and Comparative Examples 1 to 4: Production of Photopolymer Compositions and Holographic Recording Media) Photopolymer compositions and holographic recording media were produced in the same manner as in Example 1, except that the coinitiators were changed as shown in Table 1 below.

[0187] [Table 1]

[0188] (1) Element ratio The element ratios on the surfaces of the samples before and after recording were analyzed by the method described below.

[0189] Specifically, the sample to be analyzed was fixed on copper foil with carbon tape, which was then placed on a sample holder and fixed with clips. Data was then obtained using an X-ray photoelectron spectrometer (ESCA, model name: K-Alpha+, Thermo Fisher Scientific Inc.) according to the K-Alpha+ standard operating method (SOP-0524-Ok), and the element ratios (atomic %) on the sample surface were analyzed using Avantage software (version 5.980).

[0190] The system specifications of the ESCA equipment used are as follows:

[0191] -Base chamber pressure:1.0×10 -9 mbar -X-ray source:monochromatic Al Kα(1486.6eV) -X-ray spot size: 400μm -Mode:CAE(Constant Analyzer Energy)mode -Charge compensation:Flood gun(FG03:100μA, 0.5V)

[0192] For the surface of the as-received sample to be analyzed, an initial survey scan was performed under the following conditions to conduct qualitative analysis, and quantitative analysis was carried out by narrow scan (snap) for each element according to the qualitative analysis results. The elemental ratios at three locations per sample were confirmed, and the peak background smart method was applied for quantitative analysis. The binding energy correction of the core level spectrum was based on C 1s (284.8 eV).

[0193] <Survey scan conditions> - Binding energy of scan range: -5 eV to 1350 eV - Step size: 1 eV - Per Point dwell time: 20 ms - Periods: 2 - Pass energy: 200 eV <narrow scan conditions> - Binding energy of scan range: approximately 20 eV - Step size: ~0.16 eV - Per Point dwell time: 1 sec - Periods: 10 - 30 - Pass energy: 150 eV <Etching conditions> - Source: Ar ion - Energy: 6 keV - Cluster size: 75 - Rater size: 1.6 × 1.0 mm 2 - Mode: GCIB

[0194] All of the photopolymer compositions produced in the Examples and Comparative Examples contained 25 g, 52 g, and 23 g of the polymer matrix, which accounted for the largest proportions of the solids, the photoreactive monomer, and the fluorine-based compound, respectively, and the weight ratio of the polymer matrix:photoreactive monomer:fluorine-based compound was 25:52:23 in all cases.

[0195] As a result, the elemental ratios of all the samples produced in the examples and comparative examples were carbon 62.1 atomic %, nitrogen 0.9 atomic %, oxygen 21.0 atomic %, fluorine 6.2 atomic %, and silicon 9.8 atomic %.

[0196] Furthermore, the element ratios on the surfaces of the samples before and after recording were measured, and as a result, the element ratios on the sample surfaces before and after recording were measured to be the same.

[0197] (2) Calculation of reaction energy In order to calculate the reaction energy E2 of the above reaction formula 1, the electron donor borate anion (BX 1 X 2 X 3 X 4 The lowest excited singlet energy (S1) of the fluorine-containing ... * S1 and T1 were calculated for the optimized structure using

[0198] Since the photosensitive dye undergoes an electron reduction reaction, T1 is entered as a negative value, and since the electron donor undergoes an electron oxidation reaction, S1 is entered as a positive value, and these are added together to calculate the overall reaction energy E2.

[0199] [Table 2]

[0200] (1) Thermal stability (ΔT) The thermal stability was evaluated based on the degree of minimum transmittance change (ΔT) before and after exposure to high temperature. Specifically, a diffraction grating was recorded on an unrecorded sample that was not exposed to high temperature and an unrecorded sample that was exposed to high temperature, and then the thermal stability was evaluated based on the degree of minimum transmittance change, which was calculated using the above formula 1.

[0201] In the above formula 1, T0 is the minimum transmittance measured using a UV-Vis spectrometer in the wavelength range of 300 nm to 1,200 nm for a sample having a notch filter hologram recorded thereon after storing the unrecorded sample in a dark room under constant temperature (20°C to 25°C) and humidity (40% to 50% relative humidity) conditions, and T1 is the minimum transmittance measured in the same manner as above for a sample having a notch filter hologram recorded thereon after storing the unrecorded sample in a dark room under conditions of 60°C and 40% to 50% relative humidity for 100 hours.

[0202] The notch filter hologram was recorded using a setup as shown in Figure 1. Specifically, the manufactured photopolymer layer was laminated on a mirror, and then irradiated with a laser, whereby a notch filter hologram having periodic refractive index modulation in the thickness direction can be recorded due to interference between incident light L and light L' reflected by the mirror. In this example, the notch filter hologram was recorded with an incident angle of 0° (degree). The notch filter and Bragg reflector are optical elements that reflect only light of a specific wavelength, and have a structure in which two layers with different refractive indices are repeatedly laminated periodically at a constant thickness.

[0203] (2) Diffraction efficiency (DE) The diffraction efficiency (η) was calculated from the following formula 2 for a sample in which a notch filter hologram was recorded by the above-mentioned method.

[0204]

number

[0205] In the above formula 2, η is the diffraction efficiency, P D is the power (mW / cm) of the diffracted beam from the sample after recording. 2 ), and P T is the power of the beam transmitted through the sample after recording (mW / cm 2 ).

[0206] (3) Halo occurrence It was confirmed whether a halo was observed in the hologram recording medium. Specifically, a sample in which a notch filter hologram was recorded in the above-mentioned manner was irradiated with the incident light L that was irradiated during hologram recording to reproduce hologram optical information. Then, the reproduced hologram optical information was observed with the naked eye to confirm whether a halo, which is a cloudy area around the reproduced hologram optical information, was observed.

[0207] When no halo was observed for the holographic optical information on the recording medium, it was marked as "OK", and when a halo was observed, it was marked as "NG".

[0208] [Table 3]

[0209] Referring to Table 3, it can be seen that the photopolymer composition according to one embodiment of the invention contains an electron donor having a reaction energy of -25 kJ / mol to 0 kJ / mol with a photosensitive dye excited to a triplet state, thereby providing a holographic recording medium having excellent optical recording characteristics such as diffraction efficiency as well as excellent stability over time at high temperatures before recording. It can also be seen that the holographic recording medium manufactured in the examples can reproduce clear images without problems such as halos.

Claims

1. The present invention comprises a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol, and a photoinitiator system including a photoreactive monomer, a photosensitive dye and a coinitiator, The photopolymer composition, wherein the coinitiator comprises an electron donor having a reaction energy of −25 kJ / mol to 0 kJ / mol with a photosensitive dye excited to a triplet state.

2. The siloxane-based polymer includes a repeating unit represented by the following formula 1 (Chemical Formula 1) and an end group represented by the following formula 2 (Chemical Formula 2): 【Chemistry 1】 In the above Chemical Formula 1, Multiple R １ and R ２ are the same or different and each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms, n is an integer from 1 to 10,000; 【Chemistry 2】 In the above Chemical Formula 2, Multiple R １１ ~R １３ are the same or different and each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms, At least one repeating unit represented by the chemical formula 1 and an end group represented by the chemical formula 2, R １ , R ２ and R １１ ~R １３ The photopolymer composition of claim 1 , wherein at least one of is hydrogen.

3. 2. The photopolymer composition according to claim 1, wherein the (meth)acrylic polyol is a polymer having a structure in which a hydroxy group is bonded to a main chain or a side chain of a (meth)acrylate polymer.

4. 2. The photopolymer composition of claim 1, wherein the molar ratio of silane functional groups of the siloxane polymer to hydroxy groups of the (meth)acrylic polyol is 1.5-4.

5. The photoreactive monomers include benzyl (meth)acrylate, benzyl 2-phenyl acrylate, phenoxybenzyl (meth)acrylate, phenol (ethylene oxide) (meth)acrylate, and phenol (ethylene oxide). ２ One or more monofunctional monomers selected from the group consisting of (meth)acrylate, O-phenylphenol (ethylene oxide) (meth)acrylate, phenylthioethyl (meth)acrylate, and biphenylmethyl (meth)acrylate, and bisphenol A (ethylene oxide) ２～１０ 2. The photopolymer composition of claim 1, comprising one or more multifunctional monomers selected from the group consisting of di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisfluorene di(meth)acrylate, modified bisphenol fluorene di(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, phenol novolac epoxy (meth)acrylate, and cresol novolac epoxy (meth)acrylate, or a mixture of two or more thereof.

6. 2. The photopolymer composition of claim 1, wherein the photoreactive monomer is contained in an amount of 50 to 300 parts by weight based on 100 parts by weight of the polymer matrix.

7. The photopolymer composition of claim 1 additionally comprising a fluorine-based compound.

8. 8. The photopolymer composition according to claim 7, comprising 17% by weight to 38% by weight of the polymer matrix, 36% by weight to 58% by weight of the photoreactive monomer, and 17% by weight to 38% by weight of the fluorine-based compound, based on the total weight of the polymer matrix, the photoreactive monomer, and the fluorine-based compound.

9. The photosensitive dye includes a silicon rhodamine compound represented by the following chemical formula 4 (Chemical Formula 3): 【Chemistry 3】 In the above Chemical Formula 4, R ２１ ~R ２９ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, d and e each independently represent an integer from 0 to 3; f is an integer from 0 to 5; A － The photopolymer composition of claim 1 , wherein is an anion.

10. The electron donor includes a borate anion represented by the following chemical formula 5 (Chemical Formula 4): 【Chemistry 4】 In the above Chemical Formula 5, X １ ~X ４ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, and X １ ~X ４ The photopolymer composition of claim 1 , wherein at least one of is not an aryl group.

11. The electron donor includes one or more borate anions selected from the group consisting of borate anions represented by the following Chemical Formula 5-1 (Chemical Formula 5) and Chemical Formula 5-2 (Chemical Formula 6), 【Chemistry 5】 In the above Chemical Formula 5-1, R １０２ are each independently methyl or chlorine; R １０３ are each independently hydrogen, methyl or chlorine, and adjacent R １０２ is chlorine when is methyl, X ４’ is a linear alkyl group having 1 to 12 carbon atoms, 【Chemistry 6】 In the above Chemical Formula 5-2, R １０６ are each independently hydrogen, methyl or halogen; X ４” 2. The photopolymer composition of claim 1, wherein is a linear alkyl group having 1 to 12 carbon atoms.

12. The electron donor includes at least one selected from the group consisting of a cation represented by the following chemical formula 5-3 (chemical formula 7) and a cation represented by the following chemical formula 5-4 (chemical formula 8), 【Chemistry 7】 In the above formula 5-3, Y １ ~Y ４ two of the substituents may or may not be linked to each other to form an aliphatic ring having 4 to 10 carbon atoms; Y that does not form an aliphatic ring １ ~Y ４ each independently represents an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond, Y １ ~Y ４ are all methyl groups or two or more of the substituents are alkyl groups having 16 or more carbon atoms, 【Chemistry 8】 In the above Chemical Formula 5-4, R １０７ , R １０９ and R １１０ each independently represents a hydrogen atom, an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond; R １０８ and R １１１ wherein each independently represents an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond.

13. The photopolymer composition of claim 1 , wherein the coinitiator comprises an electron acceptor.

14. 14. The photopolymer composition of claim 13, comprising as the electron acceptor an onium salt, a triazine compound, or a mixture thereof.

15. 14. The photopolymer composition of claim 13, wherein the electron acceptor is present in an amount of 0.025 to 2 parts by weight based on 100 parts by weight of the polymer matrix.

16. A holographic recording medium comprising a photopolymer layer formed from the photopolymer composition of claim 1.

17. 17. The holographic recording medium according to claim 16, wherein the photopolymer layer contains a fluorine-based compound, and the atomic ratio of carbon is 50 atomic % to 70 atomic %, the atomic ratio of nitrogen is 0.01 atomic % to 2 atomic %, the atomic ratio of oxygen is 15 atomic % to 30 atomic %, the atomic ratio of fluorine is 3 atomic % to 12 atomic %, and the atomic ratio of silicon is 3 atomic % to 15 atomic %, relative to a total amount of carbon, nitrogen, oxygen, fluorine and silicon atoms confirmed by photoelectron spectroscopy on the surface.

18. 17. The holographic recording medium according to claim 16, wherein when a Notch filter hologram is recorded, the diffraction efficiency is 80% or more.

19. 13. A method for manufacturing a holographic recording medium, comprising: applying the photopolymer composition according to claim 1 to form a photopolymer layer; and irradiating a predetermined region of the photopolymer layer with a coherent laser to selectively polymerize a photoreactive monomer contained in the photopolymer layer, thereby recording optical information.

20. An optical element comprising the holographic recording medium according to claim 16.

Images