Hologram recording medium, method for manufacturing same, and optical element comprising same

Abstract

The present invention relates to a hologram recording medium, a method for manufacturing same, and an optical element comprising same. Since the proportion of elemental fluorine on the surface of a photopolymer layer is controlled to be in a specific range, the hologram recording medium may have excellent optical recording characteristics and low haze, and can provide an optical element having excellent visibility.

Description

Holographic recording medium, method for manufacturing same, and optical element including same

[0001] [Cross-reference with related application(s)]

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0076829, filed June 15, 2023, and Korean Patent Application No. 10-2024-0068785, filed May 27, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present application relates to a holographic recording medium, a method for manufacturing the same, and an optical element including the same.

[0004] A holographic recording medium records information by changing the refractive index within the holographic recording layer through an exposure process, and reproduces the information by reading the difference in the recorded refractive index.

[0005] In this regard, the photopolymer composition can be used to manufacture a hologram. The photopolymer can easily store an optical interference pattern as a hologram by photopolymerization of a photoreactive monomer. Therefore, the photopolymer can be used in various fields, such as smart devices such as mobile devices, components of wearable displays, automotive products (e.g., head-up displays), holographic fingerprint recognition systems, holographic optical elements having the functions of optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, diffractive members, light guides, waveguides, projection screens, and / or masks, media for optical memory systems, optical diffusers, optical wavelength splitters, reflective and transmissive color filters, etc.

[0006] Specifically, a photopolymer composition for hologram production comprises a polymer matrix, a photoreactive monomer, and a photoinitiator system. Then, a photopolymer layer produced from this composition is irradiated with laser interference light to induce local photopolymerization of the monomer.

[0007] This local photopolymerization process creates a refractive index modulation, which in turn creates a diffraction grating. The refractive index modulation value (△n) is influenced by the thickness and diffraction efficiency (DE) of the photopolymer layer, and the angular selectivity broadens as the thickness decreases.

[0008] Recently, there has been an increasing demand for the development of materials with high diffraction efficiency and high visibility.

[0009] According to one embodiment of the present invention, a holographic recording medium is provided.

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

[0011] According to another embodiment of the present invention, an optical element including the holographic recording medium is provided.

[0012] Hereinafter, a holographic recording medium, a method for manufacturing the same, and an optical element including the same according to specific embodiments of the invention will be described.

[0013] As used herein, “hologram recording medium” means a medium or media capable of recording optical information in the entire visible light range and ultraviolet range (e.g., 300 to 1,200 nm) through an exposure process, unless specifically stated otherwise. Therefore, the hologram recording medium in this specification may mean a medium on which optical information is recorded, or may mean a pre-recording medium capable of recording optical information. The hologram in this specification may include any visual hologram, such as an in-line (Gabor) hologram, an off-axis hologram, a full-aperture pre-hologram, a white-light transmission hologram (“rainbow hologram”), a Denisyuk hologram, a biaxial reflection hologram, an edge-literature hologram, or a holographic stereogram.

[0014] According to one embodiment of the invention, a holographic recording medium is provided, which comprises a polymer matrix formed by cross-linking a siloxane-based polymer and an acrylic polyol containing a silane functional group; a photopolymer layer containing a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorine-based compound, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine, and silicon atoms, as confirmed by electron spectroscopy for chemical analysis (ESCA) on the surface of the photopolymer layer, is 0.05 to 3 atomic %.

[0015]

[0016] The inventors of the present invention conducted research to improve the visibility of a holographic recording medium while maintaining the overall physical properties of the holographic recording medium at an excellent level, and as a result, confirmed that when the compatibility of a photopolymer composition is improved, the haze of a holographic recording medium manufactured therefrom is reduced, thereby improving visibility.

[0017] And, it was confirmed that as the compatibility of the photopolymer composition improves, the elemental ratio of fluorine on the surface of the photopolymer layer decreases. However, it was confirmed that when the elemental ratio of fluorine on the surface of the photopolymer layer becomes excessively low, the overall physical properties of the holographic recording medium deteriorate. Accordingly, it was confirmed through experiments that only when the elemental ratio of fluorine on the surface of the photopolymer layer satisfies a specific range, the overall physical properties of the holographic recording medium, such as the optical recording characteristics, are excellent, and the compatibility of the materials constituting the photopolymer layer is excellent, so that the photopolymer layer has a low haze value and thus excellent visibility can be exhibited, and the present invention was completed.

[0018] Specifically, the element ratio of the surface of the photopolymer layer can be confirmed using Electron Spectroscopy for Chemical Analysis (ESCA). According to the ESCA described in the test examples described below, the elements found on the surface of the sample to be analyzed can be qualitatively analyzed through a survey scan, and then a narrow scan can be performed for each element found to measure the element ratio. The element ratio of the photopolymer layer in the present specification can 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 in some embodiments. That is, even if the element ratio of the photopolymer layer before recording and the element ratio after recording are different beyond the error range, as long as the element ratio before or after recording is within the above-mentioned range, the intended effect of the holographic recording medium of the above embodiment can be exhibited.

[0019] The fluorine element ratio on the surface of the photopolymer layer included in the holographic recording medium of the above embodiment may be 0.05 atomic% or more, 0.06 atomic% or more, 0.07 atomic% or more, 0.08 atomic% or more, 0.09 atomic% or more, or 0.10 atomic% or more, and 3 atomic% or less, 2.9 atomic% or less, 2.8 atomic% or less, or 2.7 atomic% or less.

[0020] The elemental ratio of carbon to the total amount of carbon, oxygen, fluorine, and silicon atoms identified by ESCA on the surface of the photopolymer layer may be 50 to 80 atomic%, the elemental ratio of oxygen may be 15 to 40 atomic%, and the elemental ratio of silicon may be 0.5 to 10 atomic%.

[0021] Specifically, the carbon element ratio on the surface of the photopolymer layer may be 50 atomic% or more, 55 atomic% or more, 60 atomic% or more, 65 atomic% or more, 70 atomic% or more, 71 atomic% or more, or 72 atomic% or more, and 80 atomic% or less, 79 atomic% or less, or 78.5 atomic% or less.

[0022] The oxygen element ratio on the surface of the photopolymer layer may be 15 atomic% or more, 16 atomic% or more, or 17 atomic% or more, and 40 atomic% or less, 35 atomic% or less, 30 atomic% or less, 28 atomic% or less, 26 atomic% or less, 24 atomic% or less, or 22 atomic% or less.

[0023] The silicon element ratio on the surface of the photopolymer layer may be 0.5 atomic% or more, 1.0 atomic% or more, or 1.2 atomic% or more, and 10 atomic% or less, 9 atomic% or less, or 8 atomic% or less.

[0024] The above carbon, oxygen, fluorine and silicon element ratios are percentages (atomic %) of the total amount of carbon, oxygen, fluorine and silicon atoms identified by ESCA on the surface of the photopolymer layer.

[0025] The above photopolymer layer exhibits excellent optical recording characteristics and low haze, thereby exhibiting excellent visibility, as shown by the above-described element composition ratio. In particular, if the fluorine element ratio is below the above range, the optical recording characteristics may deteriorate, and if the fluorine element ratio exceeds the above range, the haze may increase, thereby reducing visibility.

[0026] The holographic recording medium of the above embodiment comprises a polymer matrix formed by cross-linking a siloxane-based polymer containing a silane functional group and an acrylic polyol; a photopolymer layer containing a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorine-based compound.

[0027] The above photopolymer layer may be a photopolymer layer in a state before recording that can record optical information, or a photopolymer layer in a state in which optical information is recorded.

[0028] A photopolymer layer having optical information recorded thereon can be manufactured by irradiating the photopolymer layer with object light and reference light before recording. When the photopolymer layer is irradiated with object light and reference light before recording, the photoinitiator system remains in an inactive state in the destructive interference region due to the interference fields of the object light and reference light, so photopolymerization of the photoreactive monomer does not occur, but photopolymerization of the photoreactive monomer occurs in the constructive interference region due to the activated photoinitiator system. In the constructive interference region, as the photoreactive monomer is continuously consumed, a concentration difference occurs between the photoreactive monomers in the destructive interference region and the constructive interference region. As a result, the photoreactive monomers in the destructive interference region diffuse into the constructive interference region. At this time, the fluorine-based compound, which is a plasticizer, moves in the opposite direction to the photoreactive monomers. Since the photoreactive monomer and the photopolymer formed therefrom have a high refractive index compared to the polymer matrix and the fluorine-based compound, a spatial refractive index change occurs in the photopolymer layer, and a grating is created due to the spatial refractive index modulation occurring in the photopolymer layer. This grating surface acts as a reflective surface that reflects incident light due to the difference in refractive index, and when light of the wavelength at the time of recording is incident in the direction of the reference light after recording a hologram, the Bragg condition is satisfied, so that the light is diffracted in the direction of the original object light, and the holographic optical information can be reproduced.

[0029] Therefore, if the photopolymer layer is in a pre-recording state, the photopolymer layer may include a photoreactive monomer, a photoinitiator, and a fluorine-based compound in a randomly dispersed form within the polymer matrix.

[0030] On the other hand, if optical information is recorded in the photopolymer layer, the photopolymer layer may include a photopolymer and a fluorine-based compound distributed so as to form a polymer matrix and a lattice.

[0031] The above photopolymer layer is formed from a photopolymer composition including a polymer matrix formed by cross-linking a siloxane-based polymer containing a silane functional group and an acrylic polyol, and a precursor thereof; a fluorine-based compound; a photoreactive monomer; and a photoinitiator system.

[0032] The polymer matrix is ​​formed by cross-linking a siloxane polymer containing a silane functional group (Si-H) and an acrylic polyol. Specifically, the polymer matrix is ​​formed by cross-linking an acrylic polyol with a siloxane polymer containing a silane functional group. More specifically, the hydroxyl group of the acrylic polyol can form a cross-linking bond through a hydrosilylation reaction with the silane functional group of the siloxane polymer. The hydrosilylation reaction can proceed rapidly even at a relatively low temperature (for example, at about 60°C or so) in the presence of a Pt-based catalyst. Therefore, the photopolymer layer can improve the manufacturing efficiency or productivity of a hologram recording medium by employing a polymer matrix that can be rapidly cross-linked even at a relatively low temperature as a support.

[0033] The polymer matrix described above can enhance the mobility of components (e.g., photoreactive monomers or plasticizers) included in the photopolymer layer due to the flexible main chain of the siloxane-based polymer. In addition, the siloxane bond, which has excellent heat and moisture resistance properties, can facilitate securing the reliability of the photopolymer layer on which optical information is recorded and the holographic recording medium including the same.

[0034] The polymer matrix may have a relatively low refractive index, thereby serving to increase 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 the present specification, "refractive index" may be a value measured with an Abbe refractometer at 25°C.

[0035] The above photopolymer layer includes a polymer matrix formed by cross-linking a siloxane-based polymer and an acrylic polyol containing the above-described silane functional group, but may include some non-cross-linked polymer matrix precursors. In this case, the polymer matrix precursor may refer to a siloxane-based polymer, an acrylic polyol, and a Pt-based catalyst.

[0036] The above siloxane polymer may include, for example, a repeating unit represented by the following chemical formula 1 and a terminal group represented by the following chemical formula 2.

[0037] [Chemical Formula 1]

[0038]

[0039] In the above chemical formula 1,

[0040] Multiple R's 1 and R 2 are the same or different from each other, and each independently represents hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms,

[0041] n is an integer from 1 to 10,000,

[0042] [Chemical Formula 2]

[0043]

[0044] In the above chemical formula 2,

[0045] Multiple R's 11 Inland R 13 are the same or different from each other, and each independently represents hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms,

[0046] At least one repeating unit among the repeating units represented by the above chemical formula 1 and R of one of the terminal groups among the terminal groups represented by the above chemical formula 2 1 , R 2 and R 11 Inland R 13 At least one of them is hydrogen.

[0047] In the above chemical formula 2, -(O)- means that when Si of the terminal group represented by the above chemical formula 2 is bonded to the repeating unit represented by the above chemical formula 1, it is bonded via oxygen (O) or directly without oxygen (O).

[0048] In this specification, “alkyl group” may be a straight-chain, branched-chain or cyclic alkyl group. By way of non-limiting example, the term “alkyl group” herein includes 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-methylpentyl, 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.), It can be octyl (e.g., n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, etc.), nonyl (e.g., n-nonyl, 2,2-dimethylheptyl, etc.), etc.

[0049] For example, R of the above chemical formulas 1 and 2 1 , R 2 and R 11 Inland R 13is methyl or hydrogen, and plural R 1 , R 2 and R 11 Inland R 13 At least two of them may be hydrogen. More specifically, the siloxane polymer is R of the chemical formula 1. 1 and R 2 are methyl and hydrogen, respectively, and R of the above chemical formula 2 11 Inland R 13 A compound in which each independently represents methyl or hydrogen (e.g., polymethylhydrosiloxane in which the terminal group is a trimethylsilyl group or a dimethylhydrosilyl group); some R of the above formula 1 1 and R 2 are methyl and hydrogen respectively, and the remaining R 1 and R 2 All are methyl, and R of the above chemical formula 2 11 Inland R 13 A compound in which each independently represents methyl or hydrogen (e.g., poly(dimethylsiloxane-co-methylhydrosiloxane) in which the terminal group is a trimethylsilyl group or a dimethylhydrosilyl group); or R of the above formula 1 1 and R 2 All are methyl, and R of the above chemical formula 2 11 Inland R 13 It may be a compound in which at least one of the terminal groups is hydrogen and the others are each independently methyl or hydrogen (e.g., polydimethylsiloxane in which one or both of the terminal groups are dimethylhydrosilyl groups).

[0050] The above siloxane compound may have, for example, a number average molecular weight (Mn) in the range of 200 to 4,000. Specifically, the lower limit of the number average molecular weight of the siloxane 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 above siloxane polymer satisfies the above range, problems such as a decrease in matrix crosslinking degree due to volatilization of the siloxane polymer during the crosslinking process with the acrylic polyol at room temperature or higher, or a phase separation occurring with the components of other photopolymer layers due to poor compatibility of the siloxane polymer with these components can be prevented, thereby enabling the hologram recording medium to exhibit excellent optical recording characteristics and moisture-heat resistance.

[0051] The above number average molecular weight refers to the number average molecular weight (unit: g / mol) converted to polystyrene as measured by the GPC method. In the process of measuring the number average molecular weight converted to polystyrene as measured by the GPC method, a commonly known analysis device and a detector such as a refractive index detector and an analysis column can be used, and commonly applied temperature conditions, solvents, and flow rates can be applied. Specific examples of the above measurement conditions include a temperature of 30°C, a tetrahydrofuran solvent, and a flow rate of 1 mL / min.

[0052] The silane functional group (Si-H) equivalent of the siloxane polymer may be, for example, in the range of 30 to 200 g / equivalent. More specifically, the silane functional group (Si-H) equivalent of the siloxane 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.

[0053] In this specification, the “equivalent weight of a functional group” refers to the number of equivalents in grams (also called equivalent weight) expressed in units of g / equivalent, and means the value obtained by dividing the molecular weight (weight-average molecular weight or number-average molecular weight, etc.) of a molecule or polymer containing the functional group by the number of the functional groups. 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.

[0054] When the silane functional group equivalent of the above siloxane polymer satisfies the above range, the polymer matrix has an appropriate crosslinking density to sufficiently perform its role as a support, and the fluidity of the components included in the photopolymer layer is improved, so that the initial refractive index modulation value is maintained at an excellent level even over time without the problem of the boundary of the diffraction gratings generated after recording collapsing, thereby minimizing the decrease in recording characteristics for optical information.

[0055] The above acrylic polyol may refer to a polymer having one or more, specifically two or more, hydroxyl groups bonded to the main chain or side chain of an acrylate polymer. In the present specification, "acrylic" refers to at least one selected from acryloyl groups, methacryloyl groups, and derivatives thereof, or a repeating unit formed by polymerization thereof, unless specifically stated otherwise, and "acrylate" refers to at least one selected from acrylates and methacrylates, or a repeating unit formed by polymerization thereof, unless specifically stated otherwise.

[0056] The above acrylic polyol may be a homopolymer of an acrylate monomer having a hydroxyl group, a copolymer of two or more acrylate monomers having hydroxyl groups, or a copolymer of an acrylate monomer having a hydroxyl group and an acrylate monomer not having a hydroxyl group. In this specification, “copolymer” is a term encompassing all random copolymers, block copolymers, and graft copolymers, unless specifically stated otherwise.

[0057] As the acrylate monomer having the above hydroxyl group, examples thereof include hydroxyalkyl (meth)acrylate or hydroxyaryl (meth)acrylate, and the like, wherein the alkyl is an alkyl having 1 to 30 carbon atoms, and the aryl may be an aryl having 6 to 30 carbon atoms. In addition, as the acrylate monomer not having the above hydroxyl group, examples thereof include alkyl (meth)acrylate or aryl (meth)acrylate, and the like, wherein the alkyl is an alkyl having 1 to 30 carbon atoms, and the aryl may be an aryl having 6 to 30 carbon atoms. In the present specification, “(meth)acrylate” is a term referring to acrylate and / or methacrylate, unless specifically stated otherwise.

[0058] The above-mentioned acrylic polyol may have, for example, a weight average molecular weight (Mw) within the range of 150,000 to 1,000,000. The weight average molecular weight refers to a weight average molecular weight converted to polystyrene measured by the GPC method described above. The lower limit of the weight average molecular weight may be, for example, 150,000 or more, 200,000 or more, or 250,000 or more. The upper limit of the weight average molecular weight 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 acrylic polyol satisfies the above range, the polymer matrix sufficiently functions as a support, so that even with the passage of time in use, the decrease in recording characteristics for optical information is small, and sufficient flexibility is provided to the polymer matrix to improve the mobility of components (e.g., photoreactive monomers or plasticizers) included in the photopolymer layer, thereby minimizing the decrease in recording characteristics for optical information.

[0059] In order to adjust the crosslinking density of the acrylic polyol by the siloxane polymer to a level advantageous for securing the function of the hologram recording medium, the hydroxyl equivalent of the acrylic polyol can be adjusted to an appropriate level.

[0060] Specifically, the hydroxyl group (-OH) equivalent of the acrylic polyol may be, for example, in the range of 500 to 3,000 g / equivalent. More specifically, the lower limit of the hydroxyl group (-OH) equivalent of the 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. And, the upper limit of the hydroxyl group (-OH) equivalent of the 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.

[0061] When the hydroxyl group (-OH) equivalent of the above acrylic polyol satisfies the above range, the polymer matrix has an appropriate crosslinking density to sufficiently perform its role as a support, and the fluidity of the components included in the photopolymer layer is improved, so that the initial refractive index modulation value is maintained at an excellent level even over time without the problem of the boundary of the diffraction gratings generated after recording collapsing, thereby minimizing the decrease in recording characteristics for optical information.

[0062] The acrylic polyol may have a glass transition temperature (Tg) in the range of, for example, -60 to -10°C. Specifically, the lower limit of the glass transition temperature may be, for example, -55°C or higher, -50°C or higher, -45°C or higher, -40°C or higher, -35°C or higher, -30°C or higher, or -25°C or higher. The upper limit of the glass transition temperature may be, for example, -15°C or lower, -20°C or lower, -25°C or lower, -30°C or lower, or -35°C or lower. When the glass transition temperature range is satisfied, the glass transition temperature may be lowered without significantly lowering the modulus of the polymer matrix, thereby increasing the mobility (fluidity) of other components within the photopolymer layer and improving the formability of the photopolymer composition. The above 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).

[0063] The refractive index of the 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 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. The upper limit of the refractive index of the acrylic polyol 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 acrylic polyol has a refractive index in the above-described range, it may contribute to increasing the refractive index modulation. The refractive index of the acrylic polyol is a theoretical refractive index and can be calculated using the refractive index of a monomer used in producing the acrylic polyol (a value measured using an Abbe refractometer at 25°C) and the fraction (mole ratio) of each monomer.

[0064] The above acrylic polyol and siloxane polymer may be included so that the molar ratio (SiH / OH) of the silane functional group (Si-H) of the siloxane polymer to the hydroxyl group (-OH) of the acrylic polyol is 1.5 to 4.

[0065] The molar ratio of the silane functional group of the siloxane polymer to the hydroxyl group of the acrylic polyol (hereinafter referred to simply as the SiH / OH molar ratio) can be calculated from the number of moles of the functional group determined from the weight of each polymer and the equivalent weight of the corresponding functional group of each polymer.

[0066] Specifically, the silane functional group equivalent of the siloxane polymer is the molecular weight (e.g., number average molecular weight) of the siloxane polymer divided by the number of silane functional groups per molecule, and the hydroxyl functional group equivalent of the acrylic polyol is the molecular weight (e.g., weight average molecular weight) of the acrylic polyol divided by the number of hydroxyl functional groups per molecule. Therefore, by dividing the weight of the siloxane polymer by the silane functional group equivalent of the siloxane polymer, the number of moles of silane functional groups can be confirmed, and by dividing the weight of the acrylic polyol by the hydroxyl group equivalent of the acrylic polyol, the number of moles of hydroxy groups can be confirmed. More specifically, taking Example 1 described below as an example, when the weight of the siloxane-based polymer used in Example 1 (2.5 g) is divided by the silane functional group equivalent weight of the siloxane-based polymer used in Example 1 (103 g / equivanlent), the number of moles of silane functional groups (0.024 mol) is calculated, and when the weight of the acrylic polyol used in Example 1 (21.5 g) is divided by the hydroxyl group equivalent weight of the acrylic polyol used in Example 1 (1802 g / equivanlent), the number of moles of hydroxy groups (0.012 mol) is calculated. When the number of moles of silane functional groups (0.024 mol) thus calculated is divided by the number of moles of hydroxy groups (0.012 mol), it is confirmed that the SiH / OH mole ratio is calculated as 2.

[0067] The lower limit of the SiH / OH molar ratio 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. The upper limit of the SiH / OH molar ratio 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 SiH / OH molar ratio range is satisfied, the polymer matrix is ​​crosslinked at an appropriate crosslinking density, thereby improving the fluidity of components for recording (e.g., photoreactive monomers and plasticizers, etc.), thereby securing excellent optical recording characteristics. In addition, even when placed in a high temperature / high humidity environment after recording, the components within the photopolymer layer are prevented from moving or deforming, or moisture, etc. from penetrating into the photopolymer layer, thereby exhibiting excellent moisture-heat resistance, etc., and exhibiting transparent optical characteristics.

[0068] The Pt-based catalyst may be, for example, Karstedt's catalyst. The Pt-based catalyst may be included in an amount of 0.01 to 2 parts by weight based on 100 parts by weight of the acrylic polyol. Specifically, the Pt-based 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 based on 100 parts by weight of the acrylic polyol. The Pt-based catalyst may be included in an amount of, for example, 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 based on 100 parts by weight of the acrylic polyol. When the above Pt series catalyst is used in the above-described content, the polymer matrix can be crosslinked at an appropriate crosslinking density to exhibit the desired optical recording properties.

[0069] The above polymer matrix precursor may additionally include, as necessary, a catalyst of a non-metal series such as a Rhodium series, an Iridium series, a Rhenium series, a Molybdenum series, an Iron series, a Nickel series, an alkali metal or alkaline earth metal series, a Lewis acid series, or a Carbene series, in addition to a Pt series catalyst.

[0070] Meanwhile, in the holographic recording medium of the above embodiment, optical information can be recorded by irradiating the photopolymer layer with object light and reference light. Due to the interference field of the object light and the reference light, photopolymerization of the photoreactive monomer does not occur in the destructive interference region, but photopolymerization of the photoreactive monomer occurs in the constructive interference region. As the photoreactive monomer is continuously consumed in the constructive interference region, a concentration difference occurs between the photoreactive monomers in the destructive interference region and the constructive interference region, and as a result, the photoreactive monomers in the destructive interference region diffuse into the constructive interference region. A diffraction grating is generated by the refractive index modulation generated in this way.

[0071] Accordingly, the photoreactive monomer may include a compound having a higher refractive index than the polymer matrix in order to implement the above-described refractive index modulation. However, not all photoreactive monomers are limited to having a higher refractive index than the polymer matrix, and at least some photoreactive monomers may have a higher refractive index than the polymer matrix in order to implement a high refractive index modulation value. For 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. The upper limit of the refractive index of the monomer included in the photoreactive monomer is not particularly limited, and may be, for example, 1.70 or less.

[0072] In the holographic recording medium of the above embodiment, the photoreactive monomer may include a monofunctional monomer having one photoreactive functional group and a multifunctional monomer 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.

[0073] The ratio of the monofunctional monomer in the photoreactive monomer is closely related to the compatibility of the materials constituting the photopolymer layer. Specifically, the weight ratio of the monofunctional monomer to the total weight of the photoreactive monomer can be adjusted to 30 to 68 wt%. More specifically, the weight ratio of the monofunctional monomer to the total weight of the photoreactive monomer can be, for example, 30 wt% or more, 31 wt% or more, 32 wt% or more, 33 wt% or more, 34 wt% or more, 35 wt% or more, 36 wt% or more, 37 wt% or more, 38 wt% or more, 39 wt% or more, 40 wt% or more, 41 wt% or more, 42 wt% or more, 43 wt% or more, 44 wt% or more, or 45 wt% or more. The weight ratio of the monofunctional monomer to the total weight of the photoreactive monomer may be, for example, 68 wt% or less, 67 wt% or less, 66 wt% or less, 65 wt% or less, 64 wt% or less, or 63 wt% or less. If the weight ratio of the monofunctional monomer is less than the above range, the compatibility of the materials constituting the photopolymer layer may be poor, the ratio of fluorine elements on the surface of the photopolymer layer may be increased, and the haze of the holographic recording medium may be increased. In addition, if the weight ratio of the monofunctional monomer exceeds the above range, the crosslinking degree of the photopolymer layer may be reduced, which may result in increased tackiness and reduced optical recording characteristics.

[0074] The above monofunctional monomer may include a monofunctional (meth)acrylate having a molecular weight of 85 to 500. Specifically, the monofunctional monomers include, for example, 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 (phenol (EO) 2 (meth)acrylate; Miwon's M142 refractive index 1.510), O-phenylphenol (ethylene oxide) (meth)acrylate (O-phenylphenol (EO) (meth)acrylate; Miwon's M1142 refractive index 1.577), phenylthioethyl (meth)acrylate (Miwon's It may include at least one selected from the group consisting of M1162 (refractive index 1.560) and biphenylmethyl (meth)acrylate.

[0075] The above multifunctional 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), bisfluorene di(meth)acrylate (Miwon's HR6022 refractive index 1.600, HR6040 refractive index 1.600, HR6042 refractive index 1.600), modified bisphenol fluorene di(meth)acrylate (Miwon's HR 6060 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).

[0076] The photopolymer layer may contain a photoreactive monomer in an amount of 50 to 300 parts by weight based on 100 parts by weight of the polymer matrix. The lower limit of the content of the photoreactive monomer may be, for example, 50 parts by weight or more, 70 parts by weight or more, 100 parts by weight or more, or 110 parts by weight or more. The upper limit of the content of the photoreactive monomer may be, for example, 300 parts by weight or less, 290 parts by weight or less, 280 parts by weight or less, or 270 parts by weight or less. In this case, the content of the reference polymer matrix refers to the sum of the contents (weights) of the acrylic polyol and the siloxane polymer forming the matrix. When the above range is satisfied, a photopolymer layer exhibiting excellent optical recording characteristics, heat and moisture resistance, and high transparency can be provided.

[0077] The above photopolymer layer includes a photoinitiator system. The photoinitiator system may refer to a combination of a photoinitiator or photosensitizer and a coinitiator that can initiate polymerization by light.

[0078] The above photopolymer layer may include a photosensitizer and a co-initiator as a photoinitiator system.

[0079] As the above photosensitizer, for example, a photosensitizing dye can be used. Specifically, the above-mentioned photosensitizing dyes include, for example, silicon rhodamine compounds, sulfonium derivatives of ceramidonine, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose bengal, thionine, basic yellow, pinacynol chloride, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, QuinaldineRed, crystal violet, At least one selected from the group consisting of Brilliant Green, Astrazon orange G, Darrow red, Pyronin Y, Basic Red 29, Pyrylium iodide, Safranin O, Cyanine, Methylene Blue, Azure A, and BODIPY can be used. As the cyanine dye, for example, Cy3 and Cy5 (H-Nu 640, Spectra) can be used.

[0080] The photopolymer layer may contain the photosensitive dye in an amount ranging from 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. The upper limit of the content of the photosensitive dye may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous to secure the desired optical recording characteristics by exhibiting an appropriate polymerization reaction speed.

[0081] The above public agent may be an electron donor, an electron acceptor, or a mixture thereof.

[0082] For example, the photopolymer composition of the above embodiment may include an electron donor as a public initiator. The electron donor may include, for example, a borate anion represented by the following chemical formula 3.

[0083] [Chemical Formula 3]

[0084] BX 1 X 2 X 3 X 4

[0085] In the above chemical formula 3, X 1 Inland 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 Inland X 4 At least one of them is not an aryl group.

[0086] When the above-mentioned alkyl group having 1 to 20 carbon atoms, alkenyl group having 2 to 20 carbon atoms, aryl group having 6 to 30 carbon atoms, arylalkyl group having 7 to 30 carbon atoms, alkylaryl group having 7 to 30 carbon atoms or allyl group is substituted, it may be substituted with one or more selected from the group consisting of a halogen, a vinyl group, a haloalkyl group having 1 to 5 carbon atoms and an alkoxy group having 1 to 5 carbon atoms.

[0087] Specifically, X 1 Inland X 3 is phenyl, methylphenyl, naphthyl or methylnaphthyl, each independently substituted or unsubstituted with one or more substituents selected from the group consisting of halogen, vinyl group, trifluoromethyl group and methoxy group, and X 4 may be a straight-chain alkyl group having 1 to 12 carbon atoms.

[0088] More specifically, the borate anion represented by the above chemical formula 3 may be, for example, at least one selected from the group consisting of borate anions represented by the following chemical formulas 3-1 and 3-2.

[0089] [Chemical Formula 3-1]

[0090]

[0091] In the above chemical formula 3-1,

[0092] R 102 are each independently methyl or halogen,

[0093] R 103 are each independently hydrogen, methyl or halogen, and adjacent R 102 If it is methyl, it is a halogen,

[0094] X 4' is a straight-chain alkyl group having 1 to 12 carbon atoms.

[0095] [Chemical Formula 3-2]

[0096]

[0097] In the above chemical formula 3-2,

[0098] R 106 are each independently hydrogen, methyl or halogen,

[0099] X 4" is a straight-chain alkyl group having 1 to 12 carbon atoms.

[0100] In the above chemical formula 4-2, R 106 are each independently hydrogen, methyl or halogen, but at least one may be halogen.

[0101] When the borate anion represented by Chemical Formula 3-1 and Chemical Formula 3-2 is used as the above electron donor, excellent heat resistance can be secured even before recording.

[0102] In the above chemical formulas 3-1 and 3-2, the halogen may be fluorine or chlorine. Among these, chlorine provides better heat resistance.

[0103] The cation combined with the above borate anion may be one or more cations selected from the group consisting of alkali metal cations, quaternary ammonium cations, and nitrogen-containing heterocyclic cations that do not absorb light.

[0104] The above alkali metal cation may be, for example, at least one selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium.

[0105] The above quaternary ammonium cation may be an ammonium cation in which nitrogen (N) is substituted with four substituents, a cyclic ammonium cation in which two substituents substituted on nitrogen are linked to each other, or a mixture thereof.

[0106] Specifically, the quaternary ammonium cation may be a cation represented by the following chemical formula 3-3.

[0107] [Chemical Formula 3-3]

[0108] NY1 Y 2 Y 3 Y 4

[0109] In the above chemical formula 3-3, Y 1 Inland 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,

[0110] Y that does not form an aliphatic ring 1 Inland 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 connected via an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3, etc.).

[0111] Y 1 Inland Y 4 Those in which all are methyl groups or in which two or more substituents are alkyl groups having 16 or more carbon atoms are excluded.

[0112] In the above chemical formula 3-3, Y 1 Inland Y 4 If all of the substituents are methyl groups, or if two or more substituents are alkyl groups having 16 or more carbon atoms, the electron donor may not dissolve well in the photopolymer composition, and thus the desired optical recording properties may not be exhibited.

[0113] Specifically, Y 1 Inland Y 4 The two substituents can be linked to each other to form piperidine or pyrrolidine.

[0114] Above Y 1 Inland Y 4 The substituents that do not form a central aliphatic ring may each independently be a straight-chain alkyl group having 1 to 32 carbon atoms, a phenyl group, a benzyl group, or -CH2CH2-O-CO-CH2CH2CH3. More specifically, the Y 1 Inland Y 4The substituents that do not form a central 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.

[0115] The above nitrogen-containing heterocyclic cation may be a heteroaromatic cyclic cation containing one or more nitrogens. Examples of such heteroaromatic cyclic cations include cations of pyrrole, pyrazole, imidazole, or pyridine, and the hydrogens of these may be substituted or unsubstituted.

[0116] For example, the nitrogen-containing heterocyclic cation may be a cation represented by the following chemical formula 3-4.

[0117] [Chemical Formula 3-4]

[0118]

[0119] In the above chemical formula 3-4, R 107 , R 109 and R 110 are each independently hydrogen, 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 connected via an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3, etc.),

[0120] R 108 and R 111 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 connected via an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3, etc.).

[0121] Specifically, R 107 , R 109 and R 110 Each of R can independently be hydrogen or an aryl group having 6 to 30 carbon atoms. More specifically, R 107 , R 109 and R 110Each can independently be a hydrogen or phenyl group.

[0122] Specifically, the above R 108 and R 111 It may be a straight-chain alkyl group having 1 to 40 carbon atoms or an arylalkyl group having 6 to 40 carbon atoms. More specifically, the R 108 and R 111 It can be a hexadecyl group or a benzyl group.

[0123] The cation combined with the borate anion may include, for example, at least one selected from the group consisting of a tetrabutyl ammonium cation, a hexadecyl dimethyl benzyl ammonium cation, a hentriacontyl dimethyl benzyl ammonium cation, a hexadecyl benzyl piperidinium cation, a hexadecyl benzyl pyrrolidinium cation, a 1-hexadecyl-3-benzylimidazolium cation, and a 1,3-dihexadecyl-2-phenylimidazolium cation.

[0124] However, the cations combined with the borate anion are not limited to the cations described above, and even if they exhibit poor solubility when included alone, some of the cations described above may be substituted with other cations known in the relevant technical field as long as they can exhibit appropriate solubility when mixed with the cations described above. As a non-limiting example, some of the cations described above may be substituted with 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium, etc.

[0125] For example, the photopolymer layer may include an electron acceptor as a public agent. The electron acceptor may include, for example, an onium salt such as a sulfonium salt, an iodonium salt, or the like; a triazine compound such as tris(trihalomethyl)triazine, a substituted bis(trihalomethyl)triazine, or the like; or a mixture thereof.

[0126] For example, the electron acceptor may include an iodonium salt such as (4-(octyloxy)phenyl)(phenyl)iodonium salt, or a triazine compound such as 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine. For example, commercially available H-Nu 254 (Spectra) or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine (TCI) may be used as the electron acceptor.

[0127] The photopolymer layer may contain the co-polymer in an amount of 0.05 to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the co-polymer 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. The upper limit of the content of the co-polymer may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous to secure the desired optical recording characteristics by exhibiting an appropriate polymerization reaction rate.

[0128] The above photoinitiator system may include an additional photoinitiator to remove the color of the photosensitive dye after light irradiation for recording and to react any unreacted photoreactive monomer. As the photoinitiator, for example, imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxy pyridinium salts, thioxanthone derivatives, amine derivatives, diazonium salts, sulfonium salts, iodonium salts, sulfonic acid esters, imide sulfonates, dialkyl-4-hydroxy sulfonium salts, aryl sulfonic acid-p-nitro benzyl esters, silanol-aluminum complexes, (η6-benzene)(η5-cyclopentadienyl)iron(II), benzoin tosylate, 2,5-dinitro benzyl tosylate, N-tosylphthalic acid imide, or mixtures thereof can be used.More specifically, the photoinitiator includes 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: Irgacure 651 / manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure 184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure 369 / manufacturer: BASF), Examples include, but are not limited to, bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium (product name: Irgacure 784 / manufacturer: BASF), Ebecryl P-115 (manufacturer: SK entis), Cyracure UVI-6970, Cyracure UVI-6974, Cyracure UVI-6990 (manufacturer: Dow Chemical Co. in USA), Irgacure 264, Irgacure 250 (manufacturer: BASF), CIT-1682 (manufacturer: Nippon Soda), or mixtures thereof.

[0129] The photopolymer layer may contain the photoinitiator in an amount of 0.05 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. The upper limit of the content of the photoinitiator may be, for example, 5 parts by weight or less. When the above range is satisfied, after recording optical information in the photopolymer layer, the reaction of the photoreactive monomer can be effectively terminated and the color of the photosensitive dye can be bleached, thereby providing a transparent hologram recording medium.

[0130] The above photopolymer layer includes a fluorine-based compound as a plasticizer. The plasticizer can more easily implement refractive index modulation during the manufacture of a holographic recording medium. More specifically, the plasticizer lowers the glass transition temperature of the polymer matrix, thereby improving the fluidity of the photoreactive monomer. Furthermore, the plasticizer has low refractive index and non-reactivity characteristics, and is uniformly distributed within the polymer matrix. When the non-photopolymerized photoreactive monomer moves, it can move in the opposite direction, thereby contributing to refractive index modulation. In addition, the plasticizer can also contribute to improving the formability of the photopolymer composition.

[0131] The above fluorine-based compound may have a low refractive index of 1.45 or less in order to perform the above-described plasticizer function. 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. 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 the fluorine-based compound having a lower refractive index than the above-described photoreactive monomer is used, the refractive index of the polymer matrix can be further lowered, and the refractive index modulation with the photoreactive monomer can be further increased.

[0132] The fluorine-based compound may include, 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 including a repeating unit represented by the following chemical formula 4.

[0133] [Chemical Formula 4]

[0134]

[0135] In the above chemical formula 5,

[0136] Multiple R's 31 Inland R 34 are each independently hydrogen or fluorine, and at least R 31 Inland R 34 One of them is fluorine, and m is an integer from 2 to 12.

[0137] The above fluorine compound may be, more specifically, a compound containing 1 to 3 units represented by the following chemical formula 4-1.

[0138] [Chemical Formula 4-1]

[0139]

[0140] In the above chemical formula 4-1,

[0141] R 41 Inland R 44 and R 53 Inland R 56 are each independently hydrogen or fluorine, and R 45 Inland R 52 is fluorine.

[0142] For example, in the chemical formula 4-1, R 41 , R 42 , R 55 and R 56 is hydrogen, and R 43 Inland R 54 is fluorine.

[0143] The fluorine-containing compound including the (repeating) unit represented by the above chemical formulae 4 and 4-1 is not particularly limited, but may be capped with an end capping agent widely used in the related technical field. For example, the terminal of the fluorine-containing compound including the (repeating) unit represented by the above chemical formulae 4 and 4-1 may be an alkyl group or an alkyl group substituted with one or more alkoxy groups. As a non-limiting example, the terminal of the fluorine-containing compound including the (repeating) unit represented by the above chemical formulae 4 and 4-1 may be a 2-methoxyethoxymethyl group by using 2-methoxyethoxymethyl chloride as the end capping agent.

[0144] The above 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. The upper limit of the weight average molecular weight of the fluorine-based compound may be, for example, 1000 or less, 900 or less, 800 or less, 700 or less, or 600 or less. Considering refractive index modulation, compatibility with other components, dissolution problems of the fluorine-based compound, etc., it is preferable to satisfy the above weight average molecular weight range. In this case, the above weight average molecular weight means a weight average molecular weight converted to polystyrene measured by the GPC method as described above.

[0145] The photopolymer layer may contain 20 to 200 parts by weight of the fluorine-based compound based on 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, or 70 parts by weight or more. The upper limit of the content of the fluorine-based compound 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 155 parts by weight or less. When the above range is satisfied, the fluorine-based compound having a sufficiently low refractive index can exhibit a large refractive index modulation value after recording without problems such as poor compatibility with components included in the photopolymer layer, resulting in some of the fluorine-based compound being eluted to the surface of the photopolymer layer, or poor haze, thereby securing excellent optical recording characteristics.

[0146] Most of the components of the above photopolymer layer may be a polymer matrix, a photoreactive monomer, and a fluorine-based compound. Therefore, the element composition ratio of the surface of the photopolymer layer can be controlled through the mixing ratio of the polymer matrix, the photoreactive monomer, and the fluorine-based compound. In order to satisfy the above-described element composition ratio, the photopolymer layer may include 17 to 38 wt% of the polymer matrix, 38 to 58 wt% of the photoreactive monomer, and 17 to 38 wt% of the fluorine-based compound, based on the total weight of the polymer matrix, the photoreactive monomer, and the fluorine-based compound.

[0147] More specifically, the polymer matrix may be included in an amount of, for example, 17 wt% or more, 18 wt% or more, 19 wt% or more, or 20 wt% or more. The polymer matrix may be included in an amount of, for example, 38 wt% or less, 37 wt% or less, or 36 wt% or less. The photoreactive monomer may be included in an amount of, for example, 38 wt% or more, 39 wt% or more, 40 wt% or more, 41 wt% or more, or 42 wt% or more. The photoreactive monomer may be included in an amount of, for example, 58 wt% or less, 55 wt% or less, or 53 wt% or less. The fluorinated compound may be included in an amount of, for example, 17 wt% or more, 18 wt% or more, 19 wt% or more, or 20 wt% or more. The fluorinated compound may be included in an amount of, for example, 38 wt% or less, 35 wt% or less, 33 wt% or less, or 32 wt% or less. Within this range, a photopolymer layer satisfying the above-described element composition ratio can be provided.

[0148] The above photopolymer layer may additionally include additives such as surfactants or antifoaming agents.

[0149] The above photopolymer layer may include a silicone-based surfactant, a fluorine-based surfactant, or a mixture thereof as a surfactant.

[0150] Examples of the silicone surfactants 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 from BYK Chemie. BYK-380, BYK-390, BYK-3550, etc. can be used. The above fluorinated surfactants 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-486, F-487, F-172D, MCF-350SF, TF-1025SF, TF-1117SF, TF-1026SF, TF-1128, TF-1127, TF1129, manufactured by DIC (DaiNippon Ink & Chemicals). TF-1126, TF-1130, TF-1116SF, TF-1131, TF1132, TF1027SF, TF-1441, TF-1442, etc. can be used.

[0151] If the above photopolymer layer contains a surfactant, the surfactant may be contained in an amount of 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, but 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 above range is satisfied, excellent adhesiveness and releasability can be imparted to the photopolymer layer, thereby preserving excellent optical recording characteristics.

[0152] The photopolymer layer may include a silicone-based reactive additive as a defoaming agent. Commercially available products such as Tego Rad 2500 may be used as the silicone-based reactive additive. The content of the defoaming agent may be appropriately adjusted to a level that does not impede the function of the holographic recording medium.

[0153] The above photopolymer layer may be formed from a photopolymer composition containing a solvent.

[0154] The solvent may be an organic solvent, and for example, may be at least one organic solvent selected from the group consisting of ketones, alcohols, acetates, and ethers, but is not limited thereto. Specific examples of such organic solvents include at least one selected from the group consisting of 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.

[0155] The organic solvent may be added at the time when each component included in the photopolymer composition is mixed, or may be included in the photopolymer composition while each component is added in a dispersed or mixed state in the organic solvent.

[0156] The photopolymer composition may include a solvent so that the solid concentration is 1 to 90 wt%. Specifically, the photopolymer composition may include a solvent so that the solid concentration is 20 wt% or more, 25 wt% or more, or 30 wt% or more, and 50 wt% or less, 45 wt% or less, or 40 wt% or less. Within this range, the photopolymer composition exhibits appropriate flowability and can form a coating film without defects such as stripes, and no defects occur during the drying and curing processes thereof, so that a photopolymer layer exhibiting desired physical properties and surface characteristics can be formed.

[0157] The holographic recording medium of the above embodiment has excellent refractive index modulation, diffraction efficiency and driving reliability despite having a thin photopolymer layer.

[0158] The thickness of the photopolymer layer may be, for example, in the range of 5.0 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.

[0159] The holographic recording medium of the above 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 relevant technical field may be used. For example, substrates such as glass, PET (polyethylene terephthalate), TAC (triacetyl cellulose), PC (polycarbonate), and COP (cycloolefin polymer) may be used.

[0160] The hologram recording medium of the above embodiment may have high diffraction efficiency. For example, the hologram recording medium may have a diffraction efficiency of 80% or more when recording a notch filter hologram. At this time, the thickness of the photopolymer layer may be, for example, 5 to 30 μm. Specifically, when recording a notch filter hologram, the diffraction efficiency 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, or 96% or more. For example, when a red dye or a green dye is used as a photosensitizing dye and a notch filter hologram is recorded, the diffraction efficiency may be, for example, 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, or 96% or more. In this way, the hologram recording medium of the above embodiment can implement 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 below.

[0161] Meanwhile, holographic recording media tend to have opaque characteristics due to the compatibility between low-refractive-index and high-refractive-index components used to record optical properties. However, the holographic recording medium of the above embodiment can exhibit highly transparent optical characteristics by controlling the fluorine element ratio on the surface of the photopolymer layer within a specific range.

[0162] For example, the haze of the holographic recording medium may be 2% or less. The upper limit of the haze may be, for example, 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, 1.0% or less, or 0.9% or less. The lower limit of the haze is not particularly limited and may be 0% or more. The haze may be measured by the method described in the test examples described below.

[0163] The holographic recording medium of the above embodiment is expected to provide various optical elements with high visibility as it exhibits excellent optical recording characteristics and high transparency optical characteristics.

[0164] The hologram recording medium of the above embodiment is not limited thereto, but may be one on which a reflective hologram or a transmissive hologram is recorded.

[0165] Meanwhile, according to another embodiment of the invention, a method for manufacturing a hologram recording medium is provided, comprising: forming a photopolymer layer by applying a photopolymer composition comprising a polymer matrix or a precursor thereof formed by cross-linking a siloxane-based polymer and an acrylic polyol containing a silane functional group; a fluorine-based compound; a photoreactive monomer; and a photoinitiator; and selectively polymerizing the photoreactive monomer contained in the photopolymer layer by irradiating a coherent laser to a predetermined region of the photopolymer layer to record optical information, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine, and silicon atoms confirmed by electron spectroscopy for chemical analysis (ESCA) on the surface of the photopolymer layer is 0.05 to 3 atomic %.

[0166] The photopolymer layer having the above-described specific fluorine element composition ratio may be a photopolymer layer included in the holographic recording medium of the above-described embodiment, and since the photopolymer layer has been described in detail above, a detailed description thereof is omitted here.

[0167] In the step of forming the photopolymer layer, a photopolymer composition comprising the above-described composition may first be prepared. When preparing the photopolymer composition, a commonly known mixer, stirrer, or mixer may be used to mix each component without particular limitation. In addition, this mixing process may be performed at a temperature ranging from 0°C to 100°C, from 10°C to 80°C, or from 20°C to 60°C.

[0168] In the step of forming the above 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 higher, 55°C or higher, 60°C or higher, 65°C or higher, or 70°C or higher, and 120°C or lower, 110°C or lower, 100°C or lower, or 90°C or lower. Through this process, a hydrosilylation reaction between the hydroxyl group of the acrylic polyol that remains unreacted and the silane functional group of the siloxane polymer can be induced, thereby maintaining high transparency and implementing the desired crosslinking density.

[0169] The photopolymer layer manufactured through the step of forming the above photopolymer layer may have a fluorine-based compound, a photoreactive monomer, a photoinitiator, and additives added as needed uniformly dispersed within the crosslinked polymer matrix.

[0170] Thereafter, when a coherent laser is irradiated on the photopolymer layer in the step of recording optical information, polymerization of the photoreactive monomer occurs in the region where constructive interference occurs, thereby forming a photopolymer, and polymerization of the photoreactive monomer does not occur or is suppressed in the region where destructive interference occurs, thereby forming a photoreactive monomer. Then, the unreacted photoreactive monomer diffuses toward the photopolymer side where the concentration of the photoreactive monomer is low, causing refractive index modulation, and a diffraction grating is generated by the refractive index modulation. Accordingly, a hologram, i.e., optical information, is recorded on the photopolymer layer having the diffraction grating.

[0171] The method for manufacturing a holographic recording medium of another embodiment of the present invention may additionally include a step of photobleaching by irradiating light to the entire photopolymer layer on which the optical information is recorded after the step of recording the optical information.

[0172] In the above-described photobleaching step, ultraviolet rays are irradiated onto the photopolymer layer on which optical information is recorded, thereby terminating the reaction of the photoreactive monomer remaining in the photopolymer layer and removing the color of the photosensitive dye. For example, in the above-described photobleaching step, ultraviolet rays (UVA) in the range of 320 to 400 nm are irradiated, thereby terminating the reaction of the photoreactive monomer and removing the color of the photosensitive dye.

[0173] Meanwhile, according to another embodiment of the invention, an optical element including the holographic recording medium is provided.

[0174] Specific examples of the optical element include smart devices such as mobile devices, components of wearable displays, automotive products (e.g., head up displays), holographic fingerprint recognition systems, holographic optical elements having the functions of optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, diffractive elements, light guides, waveguides, projection screens and / or masks, media and optical diffusion plates of optical memory systems, optical wavelength splitters, reflective and transmissive color filters, etc.

[0175] An example of an optical element including the above holographic recording medium is a holographic display device. The holographic display device includes a light source unit, an input unit, an optical system, and a display unit.

[0176] Specifically, the light source unit is a unit that irradiates a laser beam used to provide, record, and reproduce three-dimensional image information of an object in the input unit and display unit.

[0177] The above input section is a section that inputs 3D image information of an object to be recorded on a display section in advance, and specifically, it is a section that can input 3D information of an object, such as the intensity and phase of light by space, into an electrically addressed liquid crystal SLM, and at this time, an input beam can be used.

[0178] The above optical system may be composed of a mirror, a polarizer, a beam splitter, a beam shutter, a lens, etc. The above optical system may 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 readout beam, etc.

[0179] The display unit can receive three-dimensional image information of an object from an input unit, record it on a hologram plate formed of an optically addressed SLM, and reproduce a three-dimensional image of the object. At this time, the three-dimensional image information of the object can be recorded through interference between an input beam and a reference beam. The three-dimensional image information of the object recorded on the hologram plate can be reproduced as a three-dimensional image by a diffraction pattern generated by a readout 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 three-dimensional image and a position for reproducing the image.

[0180] A holographic recording medium according to one embodiment of the invention can have excellent optical recording characteristics and low haze by controlling the fluorine element ratio on the surface of a photopolymer layer within a specific range, and can provide an optical element with excellent visibility.

[0181] Fig. 1 schematically illustrates a recording equipment setup for hologram recording. Specifically, Fig. 1 schematically illustrates a process in which a laser of a predetermined wavelength is irradiated from a light source (10), and then passes through a mirror (20, 20'), an iris (30), a spatial filter (40), an iris (30'), a collimation lens (50), and a splitter (PBS, Polarized Beam Splitter) (60), and is irradiated onto a PP (hologram recording medium) (80) located on one surface of a mirror (70).

[0182] The following specific examples of the invention will further illustrate its functions and effects. However, these examples are presented as illustrative examples and do not limit the scope of the invention in any way.

[0183] In the following manufacturing examples, examples, and comparative examples, the content of raw materials, etc. refers to the content based on solid content unless otherwise specified.

[0184]

[0185] Manufacturing Example 1: Manufacturing of acrylic polyol

[0186] In a 2 L jacketed reactor, 132 g of butyl acrylate, 420 g of ethyl acrylate, and 48 g of hydroxybutyl acrylate were added, and diluted with 1,200 g of ethyl acetate. The reaction temperature was set to 60 to 70 °C, and stirring was performed for about 30 minutes to 1 hour. 0.42 g of n-dodecyl mercaptan (n-DDM) was additionally added, and stirring was performed for about another 30 minutes. Thereafter, 0.24 g of AIBN, a polymerization initiator, was added, and polymerization was performed at the reaction temperature for more than 4 hours until the residual acrylate content became less than 1%, thereby producing an acrylate copolymer (weight average molecular weight of about 300,000, OH equivalent of about 1802 g / equivalent) in which the hydroxyl group was located in the branched chain.

[0187]

[0188] Manufacturing Example 2: Manufacturing of fluorine compounds

[0189] 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 added, dissolved in 500 g of tetrahydrofuran, and 4.40 g of sodium hydride (60% dispersion in mineral oil) was carefully added several times while stirring at 0 °C. After stirring at 0 °C for 20 minutes, 12.50 mL of 2-methoxyethoxymethyl chloride was slowly dropped. When it was confirmed that all the reactants were consumed by 1H NMR, 29 g of a liquid product with a purity of 95% or more was obtained in a yield of 98% through work-up using dichloromethane. The weight average molecular weight of the manufactured fluorine compound is 586, and the refractive index measured by an Abbe refractometer is 1.361.

[0190]

[0191] Example 1: Manufacturing of a holographic recording medium

[0192] (1) Preparation of photopolymer composition

[0193] Trimethylsilyl terminated poly(methylhydrosiloxane) (manufactured by Sigma-Aldrich, number average molecular weight: approximately 390, SiH equivalent: approximately 103 g / equivalent) as a siloxane polymer and the acrylic polyol manufactured in Manufacturing Example 1 were first mixed. The content of the acrylic polyol was 21.5 g, and the siloxane polymer was added so that the SiH / OH molar ratio was 2. In Example 1, the siloxane polymer was added in an amount of 2.5 g.

[0194] Then, 48 g of a photoreactive monomer containing bisfluorene diacrylate and O-phenylphenol (ethylene oxide) (meth)acrylate (OPPEA) mixed in a weight ratio of 68:32, 0.2 g of H-Nu 640 (Spectra) as a red dye as a photosensitive dye, 0.8 g of hexadecyl dimethyl benzyl ammonium tri(p-chlorophenyl)butyl borate as a co-initiator, 0.05 g of H-Nu 254 (Spectra), 0.9 g of Irgacure 369 as a photoinitiator, 24 g of the fluorine-based compound prepared in Preparation Example 2 as a plasticizer, and 206 g of methyl isobutyl ketone (MIBK) as a solvent were added, and the mixture was stirred for about 30 minutes with a paste mixer in a light-blocking state. Afterwards, 0.014 g of Karstedt (Pt series) catalyst was added for matrix crosslinking to prepare a photopolymer composition.

[0195]

[0196] (2) Manufacturing of holographic recording media

[0197] The above photopolymer composition was coated to a predetermined thickness on a 60 μm thick TAC substrate using a Mayer bar and dried at 80°C for 10 minutes. The thickness of the photopolymer layer after drying was approximately 15 μm.

[0198] A diffraction grating was recorded using a setup similar to that in Fig. 1. Specifically, when the manufactured photopolymer layer is laminated on a mirror and then irradiated with a laser, a notch filter hologram having a periodic refractive index modulation in the thickness direction can be recorded through interference between the incident light (L) and the light reflected from the mirror (L'). In this example, the notch filter hologram was recorded with an incident angle of 0 ° (degree). A notch filter and a Bragg reflector are optical elements that reflect only light of a specific wavelength, and have a structure in which two layers with a difference in refractive index are periodically and repeatedly laminated at a constant thickness.

[0199]

[0200] Examples 2 to 6 and Comparative Examples 1 to 3: Manufacturing of holographic recording media

[0201] A holographic recording medium was manufactured in the same manner as in Example 1, except that the type and ratio of the monofunctional monomer in the photoreactive monomer and the type of the photosensitive dye were changed as described in Table 1 below.

[0202] That is, in the case of Examples 2 and 3, the same monofunctional monomer as in Example 1 was used, but the ratio of the photoreactive monomer to the total content was increased as described in Table 1 below, while at the same time the ratio of the multifunctional monomer, bisfluorene diacrylate, was reduced to prepare a photopolymer composition, and a hologram recording medium was prepared therefrom.

[0203] In Example 4, a holographic recording medium was manufactured in the same manner as in Example 2, except that phenoxybenzyl acrylate (PBA) was used as a monofunctional monomer.

[0204] In Example 5, a holographic recording medium was manufactured in the same manner as in Example 2, except that Rhodamine 6G, a green dye, was used instead of the red dye as the photosensitive dye.

[0205] In Example 6, a holographic recording medium was manufactured in the same manner as in Example 2, except that Astrazone Orange G, a blue dye, was used instead of the red dye as the photosensitive dye.

[0206] In Comparative Example 1, a holographic recording medium was manufactured in the same manner as Example 1, except that only bisfluorene diacrylate, a multifunctional monomer, was used as a photoreactive monomer.

[0207] In Comparative Examples 2 and 3, a holographic recording medium was manufactured in the same manner as in Example 1, except that the ratio of the monofunctional monomer to the total photoreactive monomer content was reduced or increased as described in Table 1 below, and the ratio of the polyfunctional monomer was controlled by the amount decreased or increased.

[0208]

[0209] Type of monofunctional monomer Ratio of monofunctional monomer to total content of photoreactive monomer (wt%) Photosensitive dye Example 1 OPPEA32 Red Dye Example 2 OPPEA50 Red Dye Example 3 OPPEA63 Red Dye Example 4 PBA50 Red Dye Example 5 OPPEA50 Green Dye Example 6 OPPEA50 Blue Dye Comparative Example 1-0 Red Dye Comparative Example 2 OPPEA20 Red Dye Comparative Example 3 OPPEA70 Red Dye

[0210]

[0211] Comparative Example 4: Manufacturing of a Holographic Recording Medium

[0212] A hologram recording medium was manufactured in the same manner as Example 1, except that 31.4 g of the acrylic polyol manufactured in Manufacturing Example 1, 3.6 g of the siloxane polymer, 35 g of HR 6042 (Miwon, refractive index 1.60) as a photoreactive monomer, 0.2 g of the compound represented by the following chemical formula a as a photosensitive dye, and 30 g of the fluorine-based compound manufactured in Manufacturing Example 2 as a plasticizer were used.

[0213] [chemical formula a]

[0214]

[0215]

[0216] Test Example: Performance Evaluation of Holographic Recording Media

[0217] (1) Element ratio

[0218] The element ratios on the surface of the sample before recording were analyzed by the method described below.

[0219] Specifically, the sample to be analyzed was fixed on copper foil with carbon tape, placed on a sample holder, and secured using clips. Then, data were acquired using a photoelectron spectroscopy device for chemical analysis (ESCA, model: K-Alpha+, Thermo Fisher Scientific Inc.) according to the K-Alpha+ standard operating procedure (SOP-0524-Ok), and the elemental ratio (atomic %) on the sample surface was analyzed using Avantage software (version 5.980).

[0220] The system specifications of the ESCA device used are as follows.

[0221] - Base chamber pressure: 1.0 -9 mbar

[0222] - X-ray source: monochromatic Al Kα (1486.6 eV)

[0223] - X-ray spot size: 400 ㎛

[0224] - Mode: CAE (Constant Analyzer Energy) mode

[0225] - Charge compensation: Flood gun (FG03: 100 ㎂, 0.5 V)

[0226] A qualitative analysis was conducted on the surface of the as-received sample under the following conditions by performing an initial survey scan. Based on the qualitative analysis results, a quantitative analysis was conducted through a narrow scan (snap) for each element. The element ratios at three locations for each sample were confirmed, and the peak background smart method was applied for quantitative analysis. The binding energy of the core level spectrum was corrected based on C 1s (284.8 eV).

[0227] <Survey scan 조건>

[0228] - Scan interval binding energy: -5 ~ 1350 eV

[0229] - Step size: 1 eV

[0230] - Per Point dwell time: 20 ms

[0231] - Periods: 2

[0232] - Pass energy: 200 eV

[0233] <narrow scan 조건>

[0234] - Scan interval binding energy: approximately 20 eV

[0235] - Step size: ~ 0.16 eV

[0236] - Per Point dwell time: 1 sec

[0237] - Periods: 10~30

[0238] - Pass energy: 150 eV

[0239] <Etching 조건>

[0240] - Source: Ar ion

[0241] - Energy: 6 keV

[0242] - Cluster size: 75

[0243] - Rater size: 1.6 X 1.0 mm 2

[0244] - Mode: GCIB

[0245]

[0246] (2) Diffraction efficiency (DE)

[0247] The diffraction efficiency (η) was obtained using Equation 1 below.

[0248] [Formula 1]

[0249] η(%) = {P D / (P D + P T )} X 100

[0250] In the above equation 1, η is the diffraction efficiency, and P D is the output power (mW / cm2) of the diffracted beam of the sample after recording, and P T is the output power (mW / cm2) of the beam transmitted through the sample after recording.

[0251]

[0252] (3) Haze

[0253] A 5 cm x 5 cm specimen was prepared from a sample on which a diffraction grating was recorded. The haze of the specimen was measured using a haze meter (HM-150, A Light Source, Murakami) in accordance with JIS K 7136. The haze measurement was performed three times in total, and the average value was calculated and defined as the haze value of the sample.

[0254]

[0255] Element Ratio DE (%) Haze (%) COFSi Example 177.05 19.25 0.23.5 96.5 1.9 Example 278.0 18.3 1.12.6 93.21.7 Example 377.9 17.9 2.7 1.5 8.6 1.1 Example 474.5 21.22.12.29 1.61.5 Example 573.45 18.65 0.17.8 92.5 0.9 Example 671.2 23.6 0.15.18 1.01.8 Comparative Example 175.9 16.5 5.9 51.65 95.8 3.2 Comparative Example 265.7 21.9 5.3 7.19 4.02.9 Comparative Example 376.519.40.024.0872.90.9Comparative example 464.4225.938.141.51851.1

[0256]

[0257] Referring to Table 2 above, it is confirmed that the holographic recording medium of the above embodiment exhibits excellent optical recording characteristics and low haze as the fluorine element ratio on the surface of the photopolymer layer is controlled to 0.05 to 3 atomic %. This appears to be a result of improving the compatibility of the photopolymer composition by using a photoreactive monomer including a monofunctional monomer of a predetermined content.

[0258] Examples 2, 5, and 6 show test results of holographic recording media manufactured using red dye, green dye, and blue dye, respectively. Blue dye generally exhibits lower optical recording characteristics compared to other photosensitizing dyes. Considering this, it is confirmed that the holographic recording medium of the above embodiment exhibits excellent optical recording characteristics and low haze in all regions of red, green, and blue by controlling the fluorine element ratio on the surface of the photopolymer layer within the above range.

[0259] In contrast, in Comparative Examples 1 and 2, the monofunctional monomer was not used or was used in a very small amount, so that the fluorine element ratio on the surface of the photopolymer layer exceeded 3 atomic%. As a result, the holographic recording media of Comparative Examples 1 and 2 exhibited high haze.

[0260] In Comparative Example 3, an excessive amount of monofunctional monomer was used, resulting in a fluorine ratio of less than 0.05 atomic% on the surface of the photopolymer layer. As a result, the holographic recording medium of Comparative Example 3 exhibited a reduced degree of cross-linking, increased tackiness, and very poor recording characteristics.

[0261] In Comparative Example 4, the content of the polymer matrix and fluorine-based compound increased as the content of the total photoreactive monomer decreased, so that the fluorine element ratio on the surface of the photopolymer layer exceeded 3 atomic%. Accordingly, the holographic recording medium of Comparative Example 4 exhibited a good level of haze, but deteriorated recording characteristics.

Claims

1. A polymer matrix formed by cross-linking a siloxane-based polymer containing a silane functional group and an acrylic polyol; a photopolymer layer containing a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorine-based compound. A holographic recording medium, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine and silicon atoms, as confirmed by photoelectron spectroscopy for chemical analysis on the surface of the photopolymer layer, is 0.05 to 3 atomic%.

2. A holographic recording medium in accordance with claim 1, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine, and silicon atoms, as confirmed by photoelectron spectroscopy for chemical analysis on the surface of the photopolymer layer, is 0.05 to 2.9 atomic%.

3. A holographic recording medium according to claim 1, wherein the elemental ratio of carbon to the total amount of carbon, oxygen, fluorine, and silicon atoms confirmed by photoelectron spectroscopy for chemical analysis on the surface of the photopolymer layer is 50 to 80 atomic%, the elemental ratio of oxygen is 15 to 40 atomic%, and the elemental ratio of silicon is 0.5 to 10 atomic%.

4. In the first paragraph, the siloxane polymer comprises a repeating unit represented by the following chemical formula 1 and a terminal group represented by the following chemical formula 2, a holographic recording medium: [Chemical Formula 1] In the above chemical formula 1, Multiple R's 1 and R 2 are the same or different from each other, and each independently represents hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, n is an integer from 1 to 10,000, [Chemical Formula 2] In the above chemical formula 2, Multiple R's 11 Inland R 13 are the same or different from each other, and each independently represents hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, At least one repeating unit among the repeating units represented by the above chemical formula 1 and R of one of the terminal groups among the terminal groups represented by the above chemical formula 2 1 , R 2 and R 11 Inland R 13 At least one of them is hydrogen.

5. A holographic recording medium in the first paragraph, wherein the acrylic polyol is a polymer having a structure in which a hydroxyl group is bonded to the main chain or side chain of an acrylate polymer.

6. A holographic recording medium in claim 1, wherein the molar ratio of the silane functional group of the siloxane polymer to the hydroxyl group of the acrylic polyol is 1.5 to 4.

7. A holographic recording medium according to claim 1, wherein the photoreactive monomer comprises a monofunctional monomer and a polyfunctional monomer.

8. A holographic recording medium according to claim 7, wherein the monofunctional monomer is included in an amount of 30 to 68 wt% based on the total weight of the photoreactive monomer.

9. A hologram recording medium according to claim 1, wherein the photoreactive monomer comprises at least one monofunctional monomer selected from the group consisting of benzyl (meth)acrylate, benzyl 2-phenylacrylate, phenoxybenzyl (meth)acrylate, phenol (ethylene oxide) (meth)acrylate, phenol (ethylene oxide) 2 (meth)acrylate, O-phenylphenol (ethylene oxide) (meth)acrylate, phenylthioethyl (meth)acrylate, and biphenylmethyl (meth)acrylate.

10. In the first paragraph, the photoreactive monomer is bisphenol A (ethylene oxide). 2~10 A holographic recording medium comprising at least one polyfunctional monomer 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.

11. A holographic recording medium according to 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.

12. A holographic recording medium according to claim 1, wherein the photoinitiator system comprises a photosensitive dye and a public initiator.

13. In the 12th paragraph, the public disclosure agent comprises a borate anion represented by the following chemical formula 3, a holographic recording medium: [Chemical Formula 3] BX 1 X 2 X 3 X 4 In the above chemical formula 3, X 1 Inland 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 Inland X 4 At least one of them is not an aryl group.

14. A holographic recording medium according to claim 1, wherein the fluorine compound is contained in an amount of 20 to 200 parts by weight based on 100 parts by weight of the polymer matrix.

15. A holographic recording medium according to claim 1, wherein the photopolymer layer comprises 17 to 38 wt% of the polymer matrix, 38 to 58 wt% of the photoreactive monomer, and 17 to 38 wt% of the fluorine compound, based on the total weight of the polymer matrix, the photoreactive monomer, and the fluorine compound.

16. A hologram recording medium having a diffraction efficiency of 80% or more when recording a notch filter hologram in accordance with paragraph 1.

17. A holographic recording medium having a haze of 2% or less in the first paragraph.

18. A step of forming a photopolymer layer by applying a photopolymer composition comprising a polymer matrix or a precursor thereof formed by cross-linking a siloxane-based polymer containing a silane functional group and an acrylic polyol; a fluorine-based compound; a photoreactive monomer; and a photoinitiator; and A step of irradiating a coherent laser to a predetermined area of ​​the photopolymer layer to selectively polymerize a photoreactive monomer included in the photopolymer layer to record optical information, A method for manufacturing a holographic recording medium, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine and silicon atoms, as confirmed by photoelectron spectroscopy for chemical analysis on the surface of the photopolymer layer, is 0.05 to 3 atomic%.

19. An optical element comprising a holographic recording medium of paragraph 1.

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