Hologram recording medium, method of manufacturing same, and optical element including same

Abstract

The present disclosure relates to a hologram recording medium, a method of manufacturing the same, and an optical element including the same. The hologram recording medium can have excellent optical recording characteristics and low haze by controlling the elemental ratio of fluorine on the surface of the photopolymer layer within a specific range, and can provide an optical element having excellent visibility.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2023-0076829 filed on June 15, 2023, in the Korean Intellectual Property Office, and Korean Patent Application No. 10-2024-0068785 filed on May 27, 2024, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety.

[0003] The present disclosure relates to a hologram recording medium, a method for preparing the same, and an optical element including the same. Background Art

[0004] A hologram recording medium records information by changing the refractive index in a hologram recording layer in the medium through an exposure process, reads the change in the refractive index in the medium thus recorded, and reproduces the information.

[0005] In this regard, a photopolymer composition can be used to prepare a hologram. Photopolymers can easily store light interference patterns as holograms by photopolymerization of photoreactive monomers. Therefore, photopolymers can be used in various fields, such as smart devices such as mobile devices, wearable display components, vehicle products (e.g., head-up displays), holographic fingerprint recognition systems, optical lenses, reflectors, deflection mirrors, filters, diffuse screens, diffraction elements, light guides, waveguides, holographic optical elements with projection screen and / or mask functions, optical storage systems and light diffuser plates, optical wavelength multiplexers, reflective color filters, transmissive color filters, etc.

[0006] Specifically, a photopolymer composition for preparing a hologram comprises a polymer matrix, a photoreactive monomer, and a photoinitiator system, and a photopolymer layer prepared from such a composition is irradiated with laser interference light to cause localized photopolymerization of the monomer.

[0007] The refractive index modulation is generated by this local photopolymerization process, and a diffraction grating is generated by such refractive index modulation. The refractive index modulation value (Δn) is affected by the thickness and diffraction efficiency (DE) of the photopolymer layer, and the angular selectivity increases as the thickness decreases.

[0008] Recently, the demand for developing materials having high diffraction efficiency and high visibility has increased. Summary of the invention

[0009] Technical issues

[0010] According to one embodiment of the present disclosure, a hologram recording medium is provided.

[0011] According to another embodiment of the present disclosure, a method for preparing the hologram recording medium is provided.

[0012] According to still another embodiment of the present disclosure, there is provided an optical element including the hologram recording medium.

[0013] Technical Solution

[0014] Now, a hologram recording medium, a method for producing the same, an optical element including the same, and the like according to a specific embodiment of the present disclosure will be described.

[0015] Unless otherwise specifically stated, the term "hologram recording medium" as used herein means a medium (medium or media) on which optical information can be recorded in the entire visible light range and ultraviolet range (e.g., 300nm to 1,200nm) by an exposure process. Therefore, the hologram recording medium in this article may mean a medium on which optical information is recorded, or may mean a medium before recording that is capable of recording optical information. The hologram in this article may include all visual holograms, such as on-axis (Gabor) holograms, off-axis holograms, full-aperture transfer holograms, white light transmission holograms ("rainbow holograms"), Denisyuk holograms, off-axis reflection holograms, edge-illuminated holograms, or holographic stereograms.

[0016] According to one embodiment of the present disclosure, a hologram recording medium is provided, which includes a photopolymer layer, the photopolymer layer comprising a polymer matrix formed by cross-linking a siloxane-based polymer containing a silane functional group and an acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorinated compound, wherein the element ratio of fluorine is 0.05 atomic % to 3 atomic % based on the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by Electron Spectroscopy for Chemical Analysis (ESCA).

[0017] The present inventors have studied to improve the visibility of holographic recording media while maintaining all physical properties of the holographic recording media at excellent levels. As a result, it was determined that when the compatibility of the photopolymer composition is improved, the haze of the hologram recording medium produced therefrom is reduced and the visibility is improved.

[0018] In addition, it was determined that the element ratio of fluorine on the surface of the photopolymer layer decreases as the compatibility of the photopolymer composition increases. However, it was determined that when the element ratio of fluorine on the surface of the photopolymer layer is extremely low, the overall physical properties of the hologram recording medium deteriorate. Therefore, the inventors have experimentally found that when the element ratio of fluorine on the surface of the photopolymer layer satisfies a specific range, it is not only excellent in optical recording properties as a general physical property of the hologram recording medium, but also has excellent visibility due to the low haze derived from the excellent compatibility of the material contained in the photopolymer layer, and have completed the present invention.

[0019] Specifically, the element ratio on the surface of the photopolymer layer can be determined using electron spectroscopy for chemical analysis (ESCA). According to the ESCA described in the test example described later, the elements present on the surface of the sample to be analyzed can be qualitatively analyzed by full spectrum scanning, and then each element found can be narrowly scanned to determine the element ratio. The element ratio of the photopolymer layer in this article 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 can be the same within the experimental error range, but may be different from each other in some embodiments. That is, even if the element ratio of the photopolymer layer before recording and the element ratio after recording are different from each other by more than the error range, as long as the element ratio before recording or after recording is within the above range, the expected effect of the hologram recording medium of one embodiment can be exhibited.

[0020] The fluorine element ratio on the surface of the photopolymer layer included in the hologram recording medium of one embodiment can be 0.05 atomic % or greater, 0.06 atomic % or greater, 0.07 atomic % or greater, 0.08 atomic % or greater, 0.09 atomic % or greater, or 0.10 atomic % or greater, and 3 atomic % or less, 2.9 atomic % or less, 2.8 atomic % or less, or 2.7 atomic % or less.

[0021] Based on the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by ESCA, the element ratio of carbon is 50 atomic % to 80 atomic %, the element ratio of oxygen is 15 atomic % to 40 atomic %, and the element ratio of silicon is 0.5 atomic % to 10 atomic %.

[0022] Specifically, the carbon element ratio on the surface of the photopolymer layer can be 50 atomic % or greater, 55 atomic % or greater, 60 atomic % or greater, 65 atomic % or greater, 70 atomic % or greater, 71 atomic % or greater, or 72 atomic % or greater, and 80 atomic % or less, 79 atomic % or less, or 78.5 atomic % or less.

[0023] The oxygen element ratio on the surface of the photopolymer layer can be 15 atomic % or greater, 16 atomic % or greater, or 17 atomic % or greater, 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.

[0024] 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.

[0025] The ratio of carbon, oxygen, fluorine and silicon elements is the percentage (atomic %) of the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by ESCA.

[0026] Since the photopolymer layer exhibits the above-mentioned element ratio, it has excellent optical recording characteristics and excellent visibility due to low haze. In particular, if the fluorine element ratio is less than the above range, there may be a problem of deterioration of the optical recording characteristics. If the fluorine element ratio exceeds the above range, there may be a problem of increased haze and thus deterioration of visibility.

[0027] A hologram recording medium according to one embodiment includes a photopolymer layer comprising a polymer matrix formed by cross-linking a siloxane-based polymer containing a silane functional group and an acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorinated compound.

[0028] The photopolymer layer may be a photopolymer layer in a state before recording in which optical information can be recorded, or may be a photopolymer layer in a state in which optical information is recorded.

[0029] The photopolymer layer on which optical information is recorded can be prepared by irradiating the object light and the reference light onto the photopolymer layer before recording. When the object light and the reference light are irradiated onto the photopolymer layer before recording, due to the interference field between the object light and the reference light, the photoinitiator system exists in an inactive state in the destructive interference region, and photopolymerization of the photoreactive monomer does not occur, while in the constructive interference region, due to the activated photoinitiator system, photopolymerization of the photoreactive monomer occurs. As the photoreactive monomer is continuously consumed in the constructive interference region, a concentration difference occurs between the photoreactive monomer in the destructive interference region and the constructive interference region. As a result, the photoreactive monomer in the destructive interference region diffuses into the constructive interference region. At this time, the fluorinated compound as a plasticizer moves in the opposite direction to the photoreactive monomer. Since the photoreactive monomer and the photopolymer formed therefrom have a high refractive index compared to the polymer matrix and the fluorinated compound, a spatial variation of the refractive index occurs in the photopolymer layer. Such a grating surface acts as a reflective surface that reflects the incident light due to the difference in refractive index. When light having a wavelength at the time of recording is incident in the direction of reference light after recording a hologram, it satisfies the Bragg condition, and the light is diffracted in the direction of the original object light, which makes it reproduce holographic optical information.

[0030] Therefore, if the photopolymer layer is in a state before recording, the photopolymer layer may contain the photoreactive monomer, the photoinitiator and the fluorinated compound in the form of random dispersion in the polymer matrix.

[0031] On the other hand, if optical information is recorded on the photopolymer layer, the photopolymer layer may include a polymer matrix, a photopolymer distributed to form a grating, and a fluorinated compound.

[0032] The photopolymer layer is formed of a photopolymer composition comprising a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and an acrylic polyol, or a precursor thereof; a fluorinated compound; a photoreactive monomer; and a photoinitiator system.

[0033] The polymer matrix is ​​formed by crosslinking a siloxane-based polymer containing a silane functional group (Si-H) and an acrylic polyol. Specifically, the polymer matrix is ​​formed by crosslinking an acrylic polyol with a siloxane-based polymer containing a silane functional group. More specifically, the hydroxyl group of the acrylic polyol can form a crosslink with the silane functional group of the siloxane-based polymer through a hydrosilylation reaction. Even at a relatively low temperature (e.g., a temperature of about 60° C.), the hydrosilylation reaction can proceed rapidly under a Pt-based catalyst. Therefore, a hologram recording medium according to an embodiment of the present disclosure uses a polymer matrix that can be quickly crosslinked even at a relatively low temperature as a support, thereby being able to improve preparation efficiency and productivity.

[0034] The polymer matrix can enhance the mobility of components (e.g., photoreactive monomers or plasticizers, etc.) contained in the photopolymer layer due to the flexible main chain of the siloxane-based polymer. In addition, the siloxane bond having excellent heat resistance and wet heat resistance characteristics can help ensure the reliability of the photopolymer layer for recording optical information and the reliability of the hologram recording medium including the same.

[0035] The polymer matrix can have a relatively low refractive index, which can be used to enhance the refractive index modulation of the photopolymer layer. For example, the upper limit of the refractive index of the polymer matrix can be 1.53 or less, 1.52 or less, 1.51 or less, 1.50 or less, or 1.49 or less. In addition, the lower limit of the refractive index of the polymer matrix can be, for example, 1.40 or greater, 1.41 or greater, 1.42 or greater, 1.43 or greater, 1.44 or greater, 1.45 or greater, or 1.46 or greater. As used herein, the "refractive index" can be a value measured at 25° C. using an Abbe refractometer.

[0036] The photopolymer layer includes a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and an acrylic polyol, and may include a precursor of an uncrosslinked polymer matrix. At this time, the precursor of the polymer matrix may mean a siloxane-based polymer, an acrylic polyol, and a Pt-based catalyst.

[0037] The siloxane-based 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.

[0038] [Chemical formula 1]

[0039]

[0040] Wherein, in Chemical Formula 1,

[0041] Plural R 1 and R 2 are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and

[0042] n is an integer from 1 to 10,000,

[0043] [Chemical formula 2]

[0044]

[0045] Wherein, in Chemical Formula 2,

[0046] Plural R 11 To R 13are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and

[0047] R is selected from at least one repeating unit among the repeating units represented by Chemical Formula 1 and any one terminal group among the terminal groups represented by Chemical Formula 2. 1 , R 2 and R 11 To R 13 At least one of them is hydrogen.

[0048] In Chemical Formula 2, -(O)- means that when Si of the terminal group represented by Chemical Formula 2 is bonded to the repeating unit represented by Chemical Formula 1, it is bonded through oxygen (O) or directly bonded in the absence of oxygen (O).

[0049] As used herein, "alkyl" can be a straight chain, branched chain, or cyclic alkyl. As non-limiting examples, "alkyl" as used herein can be methyl, ethyl, propyl (e.g., n-propyl, isopropyl, etc.), butyl (e.g., n-butyl, isobutyl, tert-butyl, sec-butyl, cyclobutyl, etc.), pentyl (e.g., n-pentyl, isopentyl, neopentyl, tert-pentyl, 1,1-dimethyl-propyl, 1-ethyl-propyl, 1-methyl-butyl, cyclopentyl, etc.), hexyl (e.g., n-hexyl, 1-methylpentyl, 2- methylpentyl, 4-methylpentyl, 3,3-dimethylbutyl, 1-ethyl-butyl, 2-ethylbutyl, cyclopentylmethyl, cyclohexyl, etc.), heptyl (for example, n-heptyl, 1-methylhexyl, 4-methylhexyl, 5-methylhexyl, cyclohexylmethyl, etc.), octyl (for example, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, etc.), nonyl (for example, n-nonyl, 2,2-dimethylheptyl, etc.), and the like.

[0050] In one embodiment, R in Chemical Formula 1 and Chemical Formula 2 1 , R 2 and R 11 To R 13 is methyl or hydrogen, and R 1 , R 2 and R 11 To R 13 At least two of them may be hydrogen. More specifically, the siloxane-based polymer may be one in which R 1 and R 2 are each independently methyl and hydrogen, and R 11 To R 13 A compound in which each independently is a methyl group or a hydrogen group (for example, a polymethylhydrogensiloxane whose terminal group is a trimethylsilyl group or a dimethylhydrogensilyl group); wherein some R 1 and R 2are methyl and hydrogen respectively, and the remaining R 1 and R 2 Both are methyl, and R 11 To R 13 A compound in which each independently is a methyl group or a hydrogen group (for example, a poly(dimethylsiloxane-co-methylhydrogensiloxane) whose terminal group is a trimethylsilyl group or a dimethylhydrogensilyl group); or a compound in which R 1 and R 2 Both are methyl groups. R 11 To R 13 A compound in which at least one of the terminal groups is hydrogen and the others are each independently methyl or hydrogen (for example, a polydimethylsiloxane in which either or both of the terminal groups are dimethylhydrogensilyl groups).

[0051] As an example, the number average molecular weight (Mn) of the siloxane-based compound may be in the range of 200 to 4,000. Specifically, the lower limit of the number average molecular weight of the siloxane-based polymer may be, for example, 200 or more, 250 or more, 300 or more, or 350 or more, and the upper limit thereof may be, for example, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less, 1,500 or less, or 1,000 or less. When the number average molecular weight of the siloxane-based polymer satisfies the above range, the following problems can be prevented, so that the hologram recording medium exhibits excellent optical recording characteristics and moisture and heat resistance: during the crosslinking process with acrylic polyol at room temperature or higher, the siloxane-based polymer volatilizes and the matrix crosslinking degree decreases, or the siloxane-based polymer has poor compatibility with other components of the photopolymer layer and thus phase separation occurs between the components.

[0052] The number average molecular weight means the number average molecular weight (unit: g / mol) calculated according to polystyrene determined by the GPC method. In the process of determining the number average molecular weight calculated according to polystyrene measured by the GPC method, known analytical devices, detectors such as refractive index detectors and analytical columns can be used, and commonly used temperature, solvent and flow conditions can be used. Specific examples of measurement conditions can include a temperature of 30° C., a tetrahydrofuran solvent, and a flow rate of 1 mL / min.

[0053] The silane functional group (Si-H) equivalent of the siloxane-based polymer may be, for example, in the range of 30 g / equivalent to 200 g / equivalent. More specifically, the silane functional group (Si-H) equivalent of the siloxane-based polymer may be 50 g / equivalent or greater, 60 g / equivalent or greater, 70 g / equivalent or greater, 80 g / equivalent or greater, or 90 g / equivalent or greater, and 180 g / equivalent or less, or 150 g / equivalent or less.

[0054] As used herein, "equivalent weight of a certain functional group" simply refers to the number of gram equivalents (also referred to as equivalent weight) expressed in g / equivalent units, and means a value obtained by dividing the molecular weight (weight average molecular weight, number average molecular weight, etc.) of a molecule or polymer containing the functional group by the number of the functional group. Therefore, as the equivalent value is smaller, the density of the functional group is higher, and as the equivalent value is larger, the density of the functional group is lower.

[0055] When the silane functional group equivalent of the siloxane-based polymer satisfies the above range, the polymer matrix has an appropriate cross-linking density and thus fully serves as a support, and the mobility of the components contained in the photopolymer layer is improved, which allows the initial refractive index modulation value to be maintained at an excellent level even over time without the problem of boundary surface collapse of the diffraction grating generated after recording, thereby minimizing the reduction in the recording characteristics of the optical information.

[0056] Acrylic polyols may refer to polymers in which one or more, specifically two or more, hydroxyl groups are bonded to the main chain or side chain of an acrylate-based polymer. Unless otherwise specifically stated, "acrylic" as used herein refers to one or more selected from acryloyl, methacryloyl, and derivatives thereof, or a repeating unit formed by polymerization thereof. Unless otherwise specifically stated, "acrylate-based" as used herein refers to one or more selected from acrylate and methacrylate, or a repeating unit formed by polymerization thereof.

[0057] The acrylic polyol is a homopolymer of an acrylate-based monomer having a hydroxyl group, a copolymer of two or more types of acrylate-based monomers having a hydroxyl group, or a copolymer of an acrylate-based monomer having a hydroxyl group and an acrylate-based monomer not having a hydroxyl group. Unless otherwise specified, "copolymer" as used herein is a term that encompasses all of random copolymers, block copolymers, and graft copolymers.

[0058] The acrylate-based monomer having a hydroxyl group may include, for example, hydroxyalkyl (meth)acrylate, hydroxyaryl (meth)acrylate, etc., the alkyl group being an alkyl group having 1 to 30 carbon atoms, and the aryl group being an aryl group having 6 to 30 carbon atoms. In addition, the acrylate-based monomer not having a hydroxyl group may include, for example, alkyl (meth)acrylate, aryl (meth)acrylate, etc., the alkyl group being an alkyl group having 1 to 30 carbon atoms, and the aryl group being an aryl group having 6 to 30 carbon atoms. Unless otherwise specifically stated, "(meth)acrylate" as used herein refers to acrylate and / or methacrylate.

[0059] As an example, the weight average molecular weight (Mw) of acrylic polyol can be in the range of 150,000 to 1,000,000. Weight average molecular weight means the weight average molecular weight converted according to polystyrene measured by the GPC method as described above. For example, the lower limit of the weight average molecular weight can be 150,000 or more, 200,000 or more, or 250,000 or more, and its upper limit can 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 fully exerts its function as a support, and therefore the recording properties of optical information are less reduced even after the use time has passed, and sufficient flexibility is given to the polymer matrix, thereby being able to improve the mobility of components contained in the photopolymer layer (for example, photoreactive monomers or plasticizers, etc.) and minimize the reduction in the recording properties of optical information.

[0060] In order to adjust the crosslinking density of the acrylic polyol and the siloxane-based polymer to a level conducive to ensuring the function of the hologram recording medium, the hydroxyl equivalent of the acrylic polyol may be adjusted to an appropriate level.

[0061] Specifically, the hydroxyl (-OH) equivalent of the acrylic polyol may be, for example, in the range of 500 g / equivalent to 3,000 g / equivalent. More specifically, the lower limit of the hydroxyl (-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. In addition, the upper limit of the hydroxyl (—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.

[0062] When the hydroxyl (-OH) equivalent of the acrylic polyol satisfies the above range, the polymer matrix has an appropriate cross-linking density and thus fully serves as a support, and the mobility of the components contained in the photopolymer layer is improved, which allows the initial refractive index modulation value to be maintained at an excellent level even over time without the problem of boundary surface collapse of the diffraction grating generated after recording, thereby minimizing the reduction in the recording characteristics of the optical information.

[0063] For example, the glass transition temperature (Tg) of acrylic polyols can be in the range of -60°C to -10°C. Specifically, the lower limit of the glass transition temperature can 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, and the upper limit thereof can be, for example, -15°C or lower, -20°C or lower, -25°C or lower, -30°C or lower, or -35°C or lower. If the above glass transition temperature range is met, the glass transition temperature can be reduced without significantly reducing the modulus of the polymer matrix, thereby improving the mobility (fluidity) of other components in the photopolymer composition, and also improving the moldability of the photopolymer composition. The glass transition temperature can be measured using known methods such as DSC (Differential Scanning Calorimetry) or DMA (dynamic mechanical analysis).

[0064] The refractive index of acrylic polyol can be, for example, 1.40 or more and less than 1.50. Specifically, the lower limit of the refractive index of acrylic polyol can be, for example, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more, and the upper limit thereof can 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 acrylic polyol has a refractive index within the above range, it can contribute to improving refractive index modulation. The refractive index of acrylic polyol is a theoretical refractive index and can be calculated using the refractive index of the monomer used to prepare acrylic polyol (value measured at 25° C. using an Abbe refractometer) and the fraction (molar ratio) of each monomer.

[0065] The acrylic polyol and the siloxane-based polymer may be included such that a molar ratio (SiH / OH) of a silane functional group (Si—H) of the siloxane-based polymer to a hydroxyl group (—OH) of the acrylic polyol is 1.5 to 4.

[0066] The molar ratio of the silane functional groups of the siloxane-based polymer to the hydroxyl groups of the acrylic polyol (hereinafter referred to as SiH / OH molar ratio) can be calculated by the molar number of the functional groups determined from the weight of each polymer and the corresponding functional group equivalent of each polymer.

[0067] Specifically, the silane functional group equivalent of the siloxane-based polymer is a value obtained by dividing the molecular weight (e.g., number average molecular weight) of the siloxane-based polymer by the number of silane functional groups per molecule, and the hydroxyl equivalent of the acrylic polyol is a value obtained by dividing the molecular weight (e.g., weight average molecular weight) of the acrylic polyol by the number of hydroxyl functional groups per molecule. Therefore, if the weight of the siloxane-based polymer is divided by the silane functional group equivalent of the siloxane-based polymer, the number of moles of the silane functional group can be determined, and if the weight of the acrylic polyol is divided by the hydroxyl equivalent of the acrylic polyol, the number of moles of the hydroxyl group can be determined. More specifically, referring to Example 1 described below, if the weight of the siloxane-based polymer used in Example 1 (2.5 g) is divided by the silane functional group equivalent of the siloxane-based polymer used in Example 1 (103 g / equivalent), the number of moles of silane functional groups (0.024 mol) is calculated, and if the weight of the acrylic polyol used in Example 1 (21.5 g) is divided by the hydroxyl equivalent of the acrylic polyol used in Example 1 (1802 g / equivalent), the number of moles of hydroxyl groups (0.012 mol) is calculated. If the number of moles of silane functional groups (0.024 mol) is divided by the number of moles of hydroxyl groups (0.012 mol), the SiH / OH molar ratio is determined to be 2.

[0068] 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, and the upper limit thereof 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 ​​cross-linked at an appropriate cross-linking density to improve the mobility of recording components (e.g., photoreactive monomers and plasticizers, etc.) and ensure excellent optical recording properties, and even if the photopolymer layer is placed in a high temperature / high humidity environment after recording, it can inhibit the migration or deformation of components in the photopolymer layer and the penetration of moisture into the photopolymer layer, thereby exhibiting excellent moisture and heat resistance, etc., and exhibiting transparent optical properties.

[0069] The Pt-based catalyst may be, for example, a Karstedt catalyst, etc. Based on 100 parts by weight of the acrylic polyol, the Pt-based catalyst may be included in an amount of 0.01 to 2 parts by weight. Specifically, based on 100 parts by weight of the acrylic polyol, 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. When the Pt-based catalyst is used in the above amount, the polymer matrix can be cross-linked at an appropriate cross-linking density to exhibit desired optical recording characteristics.

[0070] In addition to the Pt-based catalyst, the precursor of the polymer matrix may optionally also contain a rhodium-based catalyst, an iridium-based catalyst, a rhenium-based catalyst, a molybdenum-based catalyst, an iron-based catalyst, a nickel-based catalyst, an alkali metal or alkaline earth metal-based catalyst, a Lewis acid-based or carbene-based non-metal catalyst.

[0071] On the other hand, in a hologram recording medium of one embodiment, optical information can be recorded by irradiating object light and reference light onto a photopolymer layer. Due to the interference field between 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 thus generated.

[0072] Therefore, the photoreactive monomer may include a compound having a higher refractive index than the polymer matrix to achieve the above-mentioned refractive index modulation. However, all photoreactive monomers are not limited to those having a higher refractive index than the polymer matrix, and at least a portion of the photoreactive monomers may have a higher refractive index than the polymer matrix to achieve a high refractive index modulation value. In one example, the photoreactive monomer may include a monomer having a refractive index of 1.50 or greater, 1.51 or greater, 1.52 or greater, 1.53 or greater, 1.54 or greater, 1.55 or greater, 1.56 or greater, 1.57 or greater, 1.58 or greater, 1.59 or greater, or 1.60 or greater. The upper limit of the refractive index of the monomer contained in the photoreactive monomer is not particularly limited, and may be, for example, 1.70 or less.

[0073] The photoreactive monomer may include at least one monomer selected from a monofunctional monomer having one photoreactive functional group and a multifunctional monomer having two or more photoreactive functional groups. The photoreactive functional group may be, for example, a (meth)acryloyl group, a vinyl group, a thiol group, etc. More specifically, the photoreactive functional group may be a (meth)acryloyl group.

[0074] The ratio of monofunctional monomers in the photoreactive monomers is closely related to the compatibility of the components contained in the photopolymer layer. Specifically, based on the total weight of the photoreactive monomers, the photoreactive monomers can include 30 wt % to 68 wt % of monofunctional monomers. More specifically, based on the total weight of the photoreactive monomers, the monofunctional monomers can be included, for example, in the following amounts: 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. Based on the total weight of the photoreactive monomers, the monofunctional monomers can be included, for example, in the following amounts: 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 components contained in the photopolymer layer is poor, and the ratio of the fluorine element on the surface of the photopolymer layer increases, and there may be a problem of increased haze of the hologram recording medium. In addition, if the weight ratio of the monofunctional monomer exceeds the above range, the crosslinking density of the photopolymer layer may decrease, resulting in increased viscosity and reduced optical recording characteristics.

[0075] The monofunctional monomer may include a monofunctional (meth)acrylate having a molecular weight of 85 to 500. Specifically, the monofunctional monomer may include, for example, at least one selected from the group consisting of benzyl (meth)acrylate (M1182 with a refractive index of 1.5140, Miwon Specialty Chemical), benzyl 2-phenylacrylate, phenoxybenzyl (meth)acrylate (M1122 with a refractive index of 1.565, Miwon Specialty Chemical), phenol (ethylene oxide) (meth)acrylate (M140 with a refractive index of 1.516, Miwon Specialty Chemical), phenol (ethylene oxide) 2 (meth)acrylate (phenol (EO) 2 (meth)acrylate; M142 with a refractive index of 1.510, Miwon Specialty Chemical), o-phenylphenol (ethylene oxide) (meth)acrylate (o-phenylphenol (EO) (meth)acrylate; M1142 with a refractive index of 1.577, Miwon Specialty Chemical), phenylthioethyl (meth)acrylate (M1162 with a refractive index of 1.560, Miwon Specialty Chemical), Chemical) and biphenyl methyl (meth)acrylate.

[0076] The multifunctional monomer may include, for example, at least one selected from the following: bisphenol A (ethylene oxide) 2至10 Di(meth)acrylate (bisphenol A (EO) 2至10(Meth)acrylates; M240 with a refractive index of 1.537, M241 with a refractive index of 1.529, M244 with a refractive index of 1.545, M245 with a refractive index of 1.537, M249 with a refractive index of 1.542, M2100 with a refractive index of 1.516, M2101 with a refractive index of 1.512, Miwon Specialty Chemical), bisphenol A epoxy di(meth)acrylate (PE210 with a refractive index of 1.557, PE2120A with a refractive index of 1.533, PE2120B with a refractive index of 1.534, PE2020C with a refractive index of 1.539, PE2120S with a refractive index of 1.556, Miwon Specialty Chemical), Chemical), bisphenol fluorene di(meth)acrylate (HR6022 with a refractive index of 1.600, HR6040 with a refractive index of 1.600, HR6042 with a refractive index of 1.600, Miwon Specialty Chemical), modified bisphenol fluorene di(meth)acrylate (HR6060 with a refractive index of 1.584, HR6100 with a refractive index of 1.562, HR6200 with a refractive index of 1.530, Miwon Specialty Chemical), tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate (M370 with a refractive index of 1.508, Miwon Specialty Chemical), phenol novolac epoxy (meth)acrylate (SC6300 with a refractive index of 1.525, Miwon Specialty Chemical), and cresol novolac epoxy (meth)acrylate (SC6400 with a refractive index of 1.522, SC6400C with a refractive index of 1.522, Miwon Specialty Chemical). Specialty Chemical).

[0077] Based on the polymer matrix of 100 weight parts, the photopolymer layer can include photoreactive monomers in an amount of 50 weight parts to 300 weight parts. For example, the lower limit of the content of photoreactive monomers can be 50 weight parts or more, 70 weight parts or more, 100 weight parts or more or 110 weight parts or more. The upper limit of the content of photoreactive monomers can be 300 weight parts or less, 290 weight parts or less, 280 weight parts or less or 270 weight parts or less. At this point, the content of the polymer matrix as a standard means the total content (weight) of the acrylic polyols and siloxane-based polymers forming the matrix. When meeting the above range, a photopolymer layer showing excellent optical recording characteristics, heat resistance and wet-heat resistance and high transparency can be provided.

[0078] The photopolymer layer comprises a photoinitiator system. The photoinitiator system may refer to a photoinitiator capable of initiating polymerization by light, or a combination of a photosensitizer and a co-initiator.

[0079] The photopolymer layer may comprise a photosensitizer and a coinitiator as photoinitiator system.

[0080] As a photosensitizer, a photosensitizer dye can be used. Specifically, the photosensitizer dye may include, for example, at least one selected from the following: a silicon rhodamine compound, a sulfonium derivative of anthraquinone (9,1-bc) naphtho (3,2,1-kl) acridine, a new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylanthraquinone (9,1-bc) naphtho (3,2,1-kl) acridine (6-acetylamino-2-methylceramidonin), eosin, erythrosine, rose red, thionine, basic yellow, chlorinated pinacol cyanol, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, lapis lazuli blue, quinaldine red, crystal violet, brilliant green, basic orange G, Darrow Red, Pyronin Y, basic red 29, pyranose, chlorinated cyanol ... I (pyran Iodide), Safranin O, Cyanine, Methylene Blue, Azure A, and BODIPY. In one example, Cy3 and Cy5 (H-Nu 640, Spectra Group Limited) can be used as cyanine dyes.

[0081] Based on 100 parts by weight of the polymer matrix, the photopolymer layer can include photosensitizer dyes in an amount of 0.01 to 10 parts by weight. Specifically, the lower limit of the content of photosensitizer dyes can 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 photosensitizer dyes can be, for example, 5 parts by weight or less. When the above range is met, it is conducive to showing a suitable polymerization reaction rate and ensuring the desired optical recording characteristics.

[0082] The coinitiator may be an electron donor, an electron acceptor, or a mixture thereof.

[0083] In one example, the photopolymer composition may include an electron donor as a co-initiator. The electron donor may include, for example, a borate anion represented by the following Chemical Formula 3.

[0084] [Chemical formula 3]

[0085] BX 1 X 2 X 3 X4

[0086] Wherein, in chemical formula 3, X 1 To X 4 are each independently an 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, each of which is substituted or unsubstituted, provided that X 1 To X 4 At least one of the groups is not an aryl group.

[0087] When an 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 is substituted, it may be substituted with at least one selected from halogen, a vinyl group, a haloalkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms.

[0088] Specifically, X 1 To X 3 may be each independently phenyl, methylphenyl, naphthyl or methylnaphthyl substituted or unsubstituted by at least one substituent selected from halogen, vinyl, trifluoromethyl and methoxy, and X 4 The straight chain alkyl group may have 1 to 12 carbon atoms.

[0089] More specifically, the borate anion represented by Chemical Formula 3 may be, for example, at least one selected from the borate anions represented by the following Chemical Formula 3-1 and Chemical Formula 3-2.

[0090] [Chemical formula 3-1]

[0091]

[0092] Among them, in chemical formula 3-1,

[0093] Each R 102 are independently methyl or halogen,

[0094] Each R 103 are independently hydrogen, methyl or halogen, provided that if the adjacent R 102 is methyl, then it is halogen, and

[0095] X 4 ' is a straight chain alkyl group having 1 to 12 carbon atoms,

[0096] [Chemical formula 3-2]

[0097]

[0098] Among them, in chemical formula 3-2,

[0099] Each R 106 are independently hydrogen, methyl or halogen, and

[0100] X 4” is a straight-chain alkyl group having 1 to 12 carbon atoms.

[0101] In Chemical Formula 4-2, each R 106 may independently be hydrogen, methyl or halogen, provided that at least one of them may be halogen.

[0102] When the borate anions represented by the following Chemical Formula 3-1 and Chemical Formula 3-2 are used as electron donors, excellent heat resistance can be ensured even before recording.

[0103] In Chemical Formula 3-1 and Chemical Formula 3-2, the halogen may be fluorine or chlorine, of which chlorine can ensure more excellent heat resistance.

[0104] The cation combined with the borate anion does not absorb light, and may be at least one cation selected from the group consisting of an alkali metal cation, a quaternary ammonium cation, and a nitrogen-containing heterocyclic cation.

[0105] The alkali metal cation may be, for example, at least one selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium.

[0106] The quaternary ammonium cation may be an ammonium cation in which nitrogen (N) is substituted with four substituents, or a cyclic ammonium cation in which two substituents substituted on nitrogen are linked to each other, or a mixture thereof.

[0107] Specifically, the quaternary ammonium cation may be a cation represented by the following Chemical Formula 3-3.

[0108] [Chemical formula 3-3]

[0109] NY 1 Y 2 Y 3 Y 4

[0110] Wherein, in chemical formula 3-3, Y 1 To Y 4 The two substituents in may be linked to each other or not to form an aliphatic ring having 4 to 10 carbon atoms, and

[0111] Y that does not form an aliphatic ring 1 To Y 4each independently is 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 by an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3, etc.),

[0112] The condition is to exclude Y 1 To Y 4 The case where all are methyl groups, or two or more substituents are alkyl groups having 16 or more carbon atoms.

[0113] In chemical formula 3-3, if Y 1 To Y 4 If all are methyl groups, or two or more substituents are alkyl groups having 16 or more carbon atoms, the electron donor may not be well dissolved in the photopolymer composition and thus may not exhibit desired optical recording characteristics.

[0114] Specifically, in Y 1 To Y 4 In the above formula (A), two substituents may be linked to each other to form a piperidine or a pyrrolidine.

[0115] In Y 1 To Y 4 In the above, the substituents not forming an aliphatic ring may each independently be a linear alkyl group having 1 to 32 carbon atoms, a phenyl group, a benzyl group, or -CH2CH2-O-CO-CH2CH2CH3. More specifically, in Y 1 To Y 4 In the above, the substituents not forming an aliphatic ring may each independently be a methyl group, a butyl group, a hexadecyl group, a hexadecyl group, a phenyl group, or a benzyl group.

[0116] The nitrogen-containing heterocyclic cation may be a heteroaromatic ring cation containing one or more nitrogen. Examples of such heteroaromatic ring cations include cations of pyrrole, pyrazole, imidazole or pyridinium, and their hydrogen may be substituted or unsubstituted.

[0117] In one example, the nitrogen-containing heterocyclic cation may be a cation represented by the following Chemical Formula 3-4.

[0118] [Chemical formula 3-4]

[0119]

[0120] In chemical formula 3-4, R 107 , R 109 and R 110each independently represents 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 by an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3, etc.), and

[0121] R 108 and R 111 Each is 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 by an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3, etc.).

[0122] Specifically, R 107 , R 109 and R 110 may each independently be hydrogen or an aryl group having 6 to 30 carbon atoms. More specifically, R 107 , R 109 and R 110 Each may independently be hydrogen or phenyl.

[0123] Specifically, R 108 and R 111 It may be a linear alkyl group having 1 to 40 carbon atoms or an aryl alkyl group having 6 to 40 carbon atoms. More specifically, R 108 and R 111 It may be hexadecyl or benzyl.

[0124] The cation combined with the borate anion may include, for example, at least one selected from the group consisting of tetrabutylammonium cation, hexadecyldimethylbenzylammonium cation, hexadecyldimethylbenzylammonium cation, hexadecylbenzylammonium cation, Cationic, hexadecylbenzylpyrrolidine Cation, 1-hexadecyl-3-benzylimidazole Cation and 1,3-dihexadecyl-2-phenylimidazole cation.

[0125] However, the cations combined with the borate anion are not limited to the above cations, and even if they show poor solubility when included alone, some of the above cations may be replaced with other cations known in the related art as long as they can show sufficient solubility when mixed with the above cations. As a non-limiting example, some of the above cations may be replaced with 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanide. etc. as an alternative.

[0126] In one example, the photopolymer layer may include an electron acceptor as a co-initiator. The electron acceptor may include, for example: Salts, such as sulfonium salts and iodine salts; triazine compounds such as tris(trihalomethyl)triazine, substituted bis(trihalomethyl)triazine, etc.; or mixtures thereof.

[0127] In one example, the electron acceptor may include iodine (4-(Octyloxy)phenyl)(phenyl)iodide Salts, or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine as a triazine compound. Examples of electron acceptors include commercially available H-Nu 254 (Spectra Group) or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine (TCI America).

[0128] Based on 100 parts by weight of the polymer matrix, the photopolymer layer may contain a coinitiator in the range of 0.05 to 10 parts by weight. Specifically, the lower limit of the content of the coinitiator 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 coinitiator may be, for example, 5 parts by weight or less. When the above range is met, it is beneficial to show an appropriate polymerization reaction rate and ensure the desired optical recording characteristics.

[0129] The photoinitiator system may contain an additional photoinitiator to remove the color of the photosensitive dye and react all unreacted photoreactive monomers after light irradiation for recording. The photoinitiator may include, for example, imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxypyridines, Onium salts, thioxanthone derivatives, amine derivatives, diazonium salts, sulfonium salts, iodine Salts, sulfonates, imide sulfonates, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-nitrobenzyl esters, silanol-aluminum complexes, (η6-phenyl)(η5-cyclopentadienyl) iron (II), benzoin toluenesulfonate, 2,5-dinitrobenzyl toluenesulfonate, N-toluenesulfonylphthalimide or mixtures thereof, etc. More specifically, the photoinitiator may include 1,3-di(tert-butyldioxycarbonyl)benzophenone, 3,3',4,4"-tetra(tert-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isobutylenesulfonate, 1,3-di(tert-butyldioxycarbonyl)benzophenone, 1,3',4,4"-tetra ... oxazolidinone, 2-mercaptobenzimidazole, 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), bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium (product name: Irgacure 784 / manufacturer: BASF), Ebecryl P-115 (manufacturer: SKEntis), Cyracure UVI-6970, Cyracure UVI-6974, Cyracure UVI-6990 (manufacturer: Dow Chemical Co., USA), Irgacure 264, Irgacure 250 (manufacturer: BASF), CIT-1682 (manufacturer: Nippon Soda) or a mixture thereof, but not limited thereto.

[0130] Based on 100 parts by weight of the polymer matrix, the photopolymer layer may contain a photoinitiator in the range of 0.05 parts by weight to 10 parts by weight. 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. If the above range is met, after recording optical information on the photopolymer layer, the reaction of the photoreactive monomer is effectively terminated, and the color of the photoreactive dye is decolorized, thereby providing a transparent hologram recording medium.

[0131] The photopolymer layer may include a fluorinated compound as a plasticizer. The plasticizer can more easily achieve refractive index modulation when recording the hologram recording medium. More specifically, the plasticizer reduces the glass transition temperature of the polymer matrix, improves the mobility of the photoreactive monomer, and has low refractive index and non-reactive properties. Therefore, when the photoreactive monomer uniformly distributed in the polymer matrix but not photopolymerized moves, it can move in the opposite direction and contribute to refractive index modulation. In addition, the plasticizer can also help improve the moldability of the photopolymer composition.

[0132] The fluorinated compound can have a low refractive index of 1.45 or less to perform the above-mentioned plasticizer function. Specifically, the upper limit of the refractive index can be, for example, 1.44 or less, 1.43 or less, 1.42 or less, 1.41 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 can be, for example, 1.30 or greater, 1.31 or greater, 1.32 or greater, 1.33 or greater, 1.34 or greater, or 1.35 or greater. Due to the use of a fluorinated compound having a refractive index lower than that of the above-mentioned photoreactive monomer, the refractive index of the polymer matrix can be further reduced, and the refractive index modulation of the photoreactive monomer can be made greater.

[0133] The fluorinated compound may include, for example, at least one functional group selected from an ether group, an ester group, and an amide group, and two or more difluoromethylene groups. More specifically, the fluorinated compound may be, for example, a compound including a repeating unit represented by the following Chemical Formula 4.

[0134] [Chemical formula 4]

[0135]

[0136] Among them, in chemical formula 5,

[0137] Plural R 31 To R 34 are each independently hydrogen or fluorine, provided that R 31 To R 34 At least one of is fluorine, and m is an integer from 2 to 12.

[0138] More specifically, the fluorinated compound may be a compound including 1 to 3 units represented by the following Chemical Formula 4-1.

[0139] [Chemical formula 4-1]

[0140]

[0141] Among them, in chemical formula 4-1,

[0142] R 41 To R 44 and R 53 To R 56 are each independently hydrogen or fluorine, and R 45 To R 52 For fluorine.

[0143] In one example, in Chemical Formula 4-1, R 41 , R 42 , R 55 and R 56 is hydrogen, and R 43To R 54 For fluorine.

[0144] The fluorinated compound containing the (repeating) unit represented by Chemical Formula 4 and Chemical Formula 4-1 is not particularly limited, but can be capped with a capping agent widely used in the relevant technical field. In one example, the end of the fluorinated compound containing the (repeating) unit represented by Chemical Formula 4 and Chemical Formula 4-1 can be an alkyl group or an alkyl group substituted with at least one alkoxy group. As a non-limiting example, 2-methoxyethoxymethyl chloride is used as a capping agent, and thus the end of the fluorinated compound containing the (repeating) unit represented by Chemical Formula 4 and Chemical Formula 4-1 can be 2-methoxyethoxymethyl.

[0145] The weight average molecular weight of the fluorinated compound can be 300 or more. Specifically, the lower limit of the weight average molecular weight of the fluorinated compound can 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 fluorinated compound can 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, outflow problems of the fluorinated compound, etc., it is preferred to meet the above weight average molecular weight range. At this time, the weight average molecular weight means the weight average molecular weight converted according to polystyrene measured by the GPC method as described above.

[0146] Based on 100 parts by weight of the polymer matrix, the photopolymer layer can include 20 to 200 parts by weight of the fluorinated compound. Specifically, the lower limit of the content of the fluorinated compound can 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 fluorinated compound can 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 met, since the fluorinated compound has a sufficiently low refractive index, it can show a large refractive index modulation value after recording, without deteriorating the compatibility with the components contained in the photopolymer layer, causing some fluorinated compounds to flow out to the surface of the photopolymer layer, or deteriorating the haze, which is therefore conducive to ensuring excellent optical recording properties.

[0147] Most components of photopolymer layer can be said to be polymer matrix, photoreactive monomer and fluorinated compound.Therefore, the element ratio on the surface of photopolymer layer can be controlled by the mixing ratio of polymer matrix, photoreactive monomer and fluorinated compound.In order to meet the above-mentioned element ratio, based on the gross weight of polymer matrix, photoreactive monomer and fluorinated compound, photopolymer layer can comprise 17 wt % to 38 wt % of polymer matrix, 38 wt % to 58 wt % of photoreactive monomer and 17 wt % to 38 wt % of fluorinated compound.

[0148] More specifically, the polymer matrix can be included in an amount of, for example, 17% by weight or more, 18% by weight or more, 19% by weight or more, or 20% by weight or more. The polymer matrix can be included in an amount of, for example, 38% by weight or less, 37% by weight or less, or 36% by weight or less. The photoreactive monomer can be included in an amount of, for example, 38% by weight or more, 39% by weight or more, 40% by weight or more, 41% by weight or more, or 42% by weight or more. The photoreactive monomer can be included in an amount of, for example, 58% by weight or less, 55% by weight or less, or 53% by weight or less. The fluorinated compound can be included in an amount of, for example, 17% by weight or more, 18% by weight or more, 19% by weight or more, or 20% by weight or more. The fluorinated compound can be included in an amount of, for example, 38% by weight or less, 35% by weight or less, 33% by weight or less, or 32% by weight or less. Within this range, a photopolymer layer satisfying the above-mentioned element ratio can be provided.

[0149] The photopolymer layer may also contain additives, such as surfactants or defoamers.

[0150] The photopolymer layer may include a silicone-based surfactant, a fluorine-based surfactant, or a mixture thereof as a surfactant.

[0151] As silicone-based surfactants, for example, 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-334, BYK-335, BYK-336, BYK-337, BYK-338, BYK-339, BYK-340, BYK-341, BYK-342, BYK-343, BYK-344, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-350, BYK-351, BYK-352, BYK-353, BYK-354, BYK-355, BYK-356, BYK-357, BYK-358, BYK-359, BYK-360, BYK-361, BYK-362, BYK-363, BYK-364, BYK-365, BYK-366, BYK-367, BYK-368, BYK-369, BYK-369 YK-335, BYK-341v344, BYK-345v346, BYK-348, BYK-354, BYK355, BYK-356, BYK-358, B YK-361, BYK-370, BYK-371, BYK-375, BYK-380, BYK-390, BYK-3550 (manufactured by BYKChemie), etc. As fluorine-based surfactants, 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, TF-1126, TF-1130, TF-1116SF, TF-1131, TF1132, TF1027SF, TF-1441, TF-1442 (manufactured by Dai Nippon Ink & Chemicals), etc.

[0152] If the 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, and 5 parts by weight or less, or 3 parts by weight or less, based on 100 parts by weight of the polymer matrix. When the above range is satisfied, it can impart excellent adhesion and release properties to the photopolymer layer, and thus maintain excellent optical recording properties.

[0153] The photopolymer layer may contain a silicone-based reactive additive as a defoaming agent. As the silicone-based reactive additive, for example, a commercially available product such as Tego Rad 2500 may be used. The content of the defoaming agent may be appropriately adjusted at a level that does not hinder the function of the hologram recording medium.

[0154] The photopolymer layer may be formed of a photopolymer composition including a solvent.

[0155] The solvent may be an organic solvent, and an example thereof may be at least one organic solvent selected from ketones, alcohols, acetates, and ethers, but is not limited thereto. Specific examples of such organic solvents include at least one selected from the following: ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or isobutyl ketone; alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or tert-butanol; acetates such as ethyl acetate, isopropyl acetate, or polyethylene glycol monomethyl ether acetate; and ethers such as tetrahydrofuran or propylene glycol monomethyl ether.

[0156] The organic solvent may be added at the point in time of mixing the respective components contained in the photopolymer composition, or may be contained in the photopolymer composition while the respective components are added in a state of being dispersed or mixed in the organic solvent.

[0157] The photopolymer composition can include solvents so that the solid content concentration is 1 wt % to 90 wt %. Specifically, the photopolymer composition can include solvents 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 the scope, the photopolymer composition shows suitable fluidity, and a coating without defects such as stripes can be formed. No defects occur during the drying and curing process, and therefore a photopolymer layer showing desired physical properties and surface properties can be formed.

[0158] The hologram recording medium of one embodiment has excellent refractive index modulation, diffraction efficiency, and driving reliability despite having a thin thickness of the photopolymer layer.

[0159] The thickness of the photopolymer layer may be, for example, in the range of 5.0 μm to 40.0 μm. Specifically, the lower limit of the thickness of the photopolymer layer may be, for example, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. In addition, 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.

[0160] The hologram recording medium according to an embodiment of the present disclosure may further include a substrate on at least one surface of the photopolymer layer. The type of substrate is not particularly limited, and those known in the relevant technical field may be used. For example, a substrate such as glass, PET (polyethylene terephthalate), TAC (triacetyl cellulose), PC (polycarbonate), or COP (cycloolefin polymer) may be used.

[0161] A hologram recording medium according to an embodiment of the present disclosure may have a high diffraction efficiency. In one example, the hologram recording medium may have a diffraction efficiency of 80% or more when recording a notch filter hologram. The thickness of the photopolymer layer may be, for example, 5 μm 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. In one 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 can 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, a hologram recording medium according to an embodiment of the present disclosure can achieve excellent diffraction efficiency even if it includes a photopolymer layer of a thin thickness. The diffraction efficiency can be measured by the method described in the test example described below.

[0162] On the other hand, since the hologram recording medium uses a mixture of a component having a low refractive index and a component having a high refractive index to record optical properties, it tends to have opaque properties due to their compatibility. However, since the hologram recording medium of one embodiment includes a photopolymer layer satisfying a specific fluorine element ratio, it exhibits highly transparent optical properties.

[0163] In one example, the haze of the hologram 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 greater. The haze may be measured, for example, by the method described in the test example described later.

[0164] The hologram recording medium of one embodiment exhibits excellent optical recording characteristics and highly transparent optical characteristics, and is therefore expected to provide various optical elements having excellent visibility.

[0165] The hologram recording medium of one embodiment is not limited thereto, but may be a medium on which a reflection hologram or a transmission hologram is recorded.

[0166] On the other hand, according to another embodiment of the present disclosure, a method for preparing a hologram recording medium is provided, which includes the following steps: applying a photopolymer composition to form a photopolymer layer, wherein the photopolymer composition comprises a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and an acrylic polyol, a fluorinated compound, a photoreactive monomer, and a photoinitiator system; and irradiating a coherent laser onto a predetermined area of ​​the photopolymer layer and selectively polymerizing the photoreactive monomer contained in the photopolymer layer to record optical information, wherein the element ratio of fluorine is 0.05 atomic % to 3 atomic % based on the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by electron spectroscopy for chemical analysis (ESCA).

[0167] The photopolymer layer having the specific fluorine element ratio may be the photopolymer layer included in the hologram recording medium of the above-mentioned embodiment, and the photopolymer layer has been previously described in detail, and thus a detailed description thereof is omitted here.

[0168] In the step of forming the photopolymer layer, a photopolymer composition including the above components may be first prepared. When preparing the photopolymer composition, in order to mix the components, a known mixer, a stirrer, etc. may be used without particular limitation. In addition, such a mixing process may be performed at a temperature in the range of 0°C to 100°C, a temperature in the range of 10°C to 80°C, or a temperature in the range of 20°C to 60°C.

[0169] In the step of forming the photopolymer layer, the prepared photopolymer composition may be applied to form a coating layer formed of the photopolymer composition. The coating layer may be dried at 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 remaining unreacted and the silane functional group of the siloxane-based polymer may be induced, thereby achieving a desired crosslinking density while maintaining high transparency.

[0170] In the photopolymer layer prepared by the step of forming the photopolymer layer, the fluorinated compound, the photoreactive monomer and the photoinitiator system and additives added as needed may be uniformly dispersed in the cross-linked polymer matrix.

[0171] Subsequently, in the step of recording optical information, if a coherent laser is irradiated onto the photopolymer layer, in the region where constructive interference occurs, polymerization of the photoreactive monomer occurs to form a photopolymer, and in the region where destructive interference occurs, polymerization of the photoreactive monomer does not occur or polymerization of the photoreactive monomer is suppressed, so that the photoreactive monomer exists. In addition, the unreacted photoreactive monomer causes refractive index modulation while diffusing toward the photopolymer side where the concentration of the photoreactive monomer is lower, and a diffraction grating is generated by the refractive index modulation. Thus, a hologram (i.e., optical information) is recorded on the photopolymer layer having a diffraction grating.

[0172] The method for preparing a hologram recording medium according to another embodiment of the present disclosure may further include a step of performing photobleaching by irradiating light onto the entire photopolymer layer on which the optical information is recorded, after the step of recording the optical information.

[0173] In the photobleaching step, ultraviolet rays are irradiated onto the photopolymer layer on which the optical information is recorded to terminate the reaction of the photoreactive monomers remaining in the photopolymer layer, thereby removing the color of the photosensitizing dye. In one example, in the photobleaching step, ultraviolet rays (UVA) in the range of 320 nm to 400 nm are irradiated to terminate the reaction of the photoreactive monomers and remove the color of the photosensitizing dye.

[0174] On the other hand, according to still another embodiment of the present disclosure, an optical element including the hologram recording medium is provided.

[0175] Specific examples of the optical element may include smart devices such as mobile devices, components of wearable displays, vehicle products (e.g., head-up displays), holographic fingerprint recognition systems, optical lenses, reflectors, deflection mirrors, filters, diffuser screens, diffraction elements, light guides, waveguides, holographic optical elements with projection screen and / or mask functions, media for optical storage systems and light diffusers, optical wavelength multiplexers, reflective color filters, transmissive color filters, and the like.

[0176] An example of an optical element including a hologram medium may include a hologram display device. The hologram display device includes a light source unit, an input unit, an optical system, and a display unit.

[0177] Specifically, the light source unit is a portion that irradiates a laser beam for providing, recording, and reproducing three-dimensional image information of an object in the input unit and the display unit.

[0178] The input unit is a part that pre-inputs three-dimensional image information of the object to be recorded on the display unit. Specifically, the three-dimensional information of the object, such as the intensity and phase of light in each space, can be input into the electrically addressed liquid crystal SLM, where an input light beam can be used.

[0179] The optical system may include a reflector, a polarizer, a beam splitter, a beam gate, a lens, etc. The optical system may be allocated into an input beam for sending a laser beam emitted from a light source unit to an input unit, a recording beam for sending a laser beam to a display unit, a reference beam, an erasing beam, a reading beam, etc.

[0180] The display unit can receive the three-dimensional image information of the object from the input unit, record it on the hologram plate containing the optically addressed SLM, and reproduce the three-dimensional image of the object. At this time, the three-dimensional image information of the object can be recorded via the interference of the input light beam and the reference light beam. The three-dimensional image information of the object recorded on the hologram plate can be reproduced as a three-dimensional image through the diffraction pattern generated by the read light beam. The erase light beam can be used to quickly remove the formed diffraction pattern. On the other hand, the hologram plate can be moved between the position of the input three-dimensional image and the position of the reproduced three-dimensional image.

[0181] Beneficial Effects

[0182] The hologram recording medium according to one embodiment of the present disclosure can have excellent optical recording characteristics and low haze by controlling the element ratio of fluorine on the surface of the photopolymer layer within a specific range, and can provide an optical element with excellent visibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0183] Figure 1 The recording device setup for hologram recording is schematically shown. Specifically, Figure 1 A process is schematically shown in which laser light of a predetermined wavelength is emitted from a light source 10 and irradiated onto a PP (hologram recording medium) 80 located on one surface of a reflector 70 via reflectors 20 and 20', an aperture 30, a spatial filter 40, an aperture 30', a collimating lens 50 and a PBS (Polarized Beam Splitter) 60. DETAILED DESCRIPTION

[0184] Hereinafter, the action and effect of the present invention will be described in more detail with reference to specific embodiments of the present invention. However, these embodiments are presented for illustrative purposes only, and the scope of the present invention is not limited thereby in any way.

[0185] In the following Preparation Examples, Examples, Comparative Examples and the like, unless otherwise specified, the content of raw materials and the like means the content based on the solid content.

[0186] Preparation Example 1: Preparation of acrylic polyol

[0187] 132g butyl acrylate, 420g ethyl acrylate and 48g hydroxybutyl acrylate are added to a 2L jacket reactor and diluted with 1200g ethyl acetate. The reaction temperature is set to 60°C to 70°C, and the mixture is stirred for about 30 minutes to 1 hour. 0.42g of n-dodecyl mercaptan (n-DDM) is further added, and further stirred for about 30 minutes. Then, 0.24g of AIBN as a polymerization initiator is added, and polymerization is carried out at the reaction temperature for 4 hours or more, and maintained until the residual acrylate content becomes less than 1%. Thus, an acrylate-based copolymer (weight average molecular weight of about 300,000, OH equivalent of about 1802g / equivalent) in which hydroxyl groups are located in the side chains is prepared.

[0188] Preparation Example 2: Preparation of fluorinated compounds

[0189] 20.51 g of 2,2'-{oxybis[(1,1,2,2-tetrafluoroethane-2,1-diyl)oxy]}bis(2,2-difluoroethane-1-ol) was added to a 1000 mL flask and dissolved in 500 g of tetrahydrofuran, to which 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 added dropwise. When all the reactants were determined to be consumed by 1H NMR, 29 g of a liquid product with a purity of 95% or more was obtained by treatment with dichloromethane, with a yield of 98%. The weight average molecular weight of the prepared fluorinated compound was 586, and the refractive index measured with an Abbe refractometer was 1.361.

[0190] Example 1: Preparation of hologram recording medium

[0191] (1) Preparation of photopolymer composition

[0192] First, trimethylsilyl-terminated poly(methylhydrogensiloxane) (Sigma-Aldrich, number average molecular weight: about 390, SiH equivalent: about 103 g / equivalent) as a siloxane-based polymer was mixed with the acrylic polyol prepared in Preparation Example 1. The content of the acrylic polyol was 21.5 g, and the siloxane-based polymer was added so that the SiH / OH molar ratio was 2. In Example 1, 2.5 g of the siloxane-based polymer was added.

[0193] Then, 48 g of a photoreactive monomer in which bisfluorene diacrylate and o-phenylphenol (ethylene oxide) (meth) acrylate (OPPEA) were mixed in a weight ratio of 68:32, 0.2 g of a red dye H-Nu 640 (Spectra) (as a photosensitizing dye), 0.8 g of hexadecyl dimethylbenzylammonium tri(p-chlorophenyl)butyl borate, and 0.05 g of H-Nu 254 (Spectra) as a coinitiator, 0.9 g of Irgacure 369 as a photoinitiator, 24 g of the fluorinated 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 while shielding from light. Thereafter, 0.014 g of a Karstedt (Pt-based) catalyst was added for matrix crosslinking to prepare a photopolymer composition.

[0194] (2) Preparation of hologram recording media

[0195] The photopolymer composition was coated on a 60 μm thick TAC substrate to a predetermined thickness using a Mayer rod, and dried at 80° C. for 10 minutes. The thickness of the photopolymer layer after drying was about 15 μm.

[0196] Use with Figure 1 The diffraction grating is recorded with the same setup as shown in . Specifically, when the prepared photopolymer layer is laminated on a reflector and then irradiated with a laser, a notch filter hologram having a periodic refractive index modulation in the thickness direction can be recorded by interference between the incident light (L) and the light (L') reflected from the reflector. In this example, the notch filter hologram is recorded at an incident angle of 0° (degrees). Notch filters and Bragg reflectors are optical elements that reflect only light of a specific wavelength, and have a structure in which two layers with different refractive indices are periodically and repeatedly stacked at a constant thickness.

[0197] Examples 2 to 6 and Comparative Examples 1 to 3: Preparation of hologram recording media

[0198] A hologram recording medium was prepared 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 photosensitizing dye were changed as shown in Table 1 below.

[0199] That is, in Example 2 and Example 3, the photopolymer composition was prepared using the same monofunctional monomer as in Example 1, except that the ratio of the multifunctional monomer bis(fluorene) diacrylate was reduced while increasing the ratio of the monofunctional monomer to the total content of the photoreactive monomer as shown in Table 1 below, and thus a hologram recording medium was prepared.

[0200] In Example 4, a hologram recording medium was prepared in the same manner as in Example 2, except that phenoxybenzyl acrylate (PBA) was used as the monofunctional monomer.

[0201] In Example 5, a hologram recording medium was prepared in the same manner as in Example 2, except that a green dye, Rhodamine 6G, was used as the photosensitizing dye instead of the red dye.

[0202] In Example 6, a hologram recording medium was prepared in the same manner as in Example 2, except that a blue dye, Basic Orange G, was used as the photosensitizing dye instead of the red dye.

[0203] In Comparative Example 1, a hologram recording medium was prepared in the same manner as in Example 1, except that only bisfluorene diacrylate, which is a multifunctional monomer, was used as the photoreactive monomer.

[0204] In Comparative Examples 2 and 3, hologram recording media were prepared in the same manner as in Example 1, except that the ratio of the monofunctional monomer relative to the total content of the photoreactive monomer was reduced or increased as shown in Table 1 below, while the ratio of the polyfunctional monomer was controlled as the monofunctional monomer was reduced or increased.

[0205] [Table 1]

[0206]

[0207] Comparative Example 4: Preparation of hologram recording medium

[0208] A hologram recording medium was prepared in the same manner as in Example 1, except that 31.4 g of the acrylic polyol prepared in Preparation Example 1, 3.6 g of a siloxane-based polymer, 35 g of HR 6042 (Miwon Specialty Chemical, refractive index 1.60) as a photoreactive monomer, 0.2 g of a compound represented by the following Chemical Formula a as a photosensitizing dye, and 30 g of the fluorinated compound prepared in Preparation Example 2 as a plasticizer were used.

[0209] [Chemical formula a]

[0210]

[0211] Test Example: Evaluation of the Performance of Hologram Recording Media

[0212] (1) Element ratio

[0213] The surface element ratios of the samples before recording were analyzed by the method described below.

[0214] Specifically, the sample to be analyzed was fixed to a copper foil with a carbon tape, placed on a sample holder and fixed with a clip. Then, data were acquired using an electron spectrometer for chemical analysis (ESCA, model name: K-Alpha+, Thermo Fisher Scientific Inc.) according to the K-Alpha+ standard operating procedure (SOP-0524-Ok), and the element ratio (atomic %) of the sample surface was analyzed using Avantage software (version 5.980).

[0215] The system specifications of the ESCA equipment used are as follows.

[0216] -Basal chamber pressure: 1.0×10 -9 millibar

[0217] -X-ray source: monochromatic Al Kα (1486.6eV)

[0218] -X-ray spot size: 400μm

[0219] -Mode: CAE (Constant Analyzer Energy) mode

[0220] - Charge compensation: flood gun (FG03: 100μA, 0.5V)

[0221] The surface of the sample to be analyzed was qualitatively analyzed in its original state using an initial full spectrum scan under the following conditions. Based on the qualitative analysis results, each element was quantitatively analyzed by narrow scanning (snapshot). The element ratios at three positions were determined for each sample, and the peak background intelligence method was applied for quantitative analysis. The binding energy correction of the core level spectrum was based on C1s (284.8 eV).

[0222] <Full spectrum scanning conditions>

[0223] -Scanning interval binding energy: -5eV to 1350eV

[0224] - Step size: 1eV

[0225] -Dwell time per point: 20 milliseconds

[0226] - Cycles: 2

[0227] - Pass energy: 200eV

[0228] <Narrow Scan Condition>

[0229] -Scanning interval binding energy: about 20eV

[0230] - Step size: about 0.16eV

[0231] -Dwell time at each point: 1 second

[0232] - Cycles: 10 to 30

[0233] - Pass energy: 150eV

[0234] <Etching Conditions>

[0235] -Source: Ar ions

[0236] -Energy: 6keV

[0237] - Cluster size: 75

[0238] -Rater size: 1.6×1.0mm 2

[0239] -Mode: GCIB

[0240] (2) Diffraction efficiency (DE)

[0241] The diffraction efficiency (η) is determined by the following Equation 1.

[0242] [Equation 1]

[0243] η(%)={P D / (P D +P T )}X100

[0244] Where, in Equation 1, η is the diffraction efficiency, P D The output of the diffracted beam from the sample after recording (mW / cm 2 ), and P T The output of the transmitted light beam of the sample after recording (mW / cm 2 ).

[0245] (3) Haze

[0246] A 5 cm×5 cm specimen was prepared from the sample on which the diffraction grating was recorded. The haze of the specimen was measured using a haze meter (HM-150, A light source, Murakami) according to 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.

[0247] [Table 2]

[0248]

[0249] Referring to Table 2, it is determined that the hologram recording medium according to one embodiment of the present disclosure has excellent optical recording characteristics and low haze by controlling the element ratio of fluorine on the surface of the photopolymer layer within a range of 0.05 atomic % to 3 atomic %. This seems to be a result of improving the compatibility of the photopolymer composition by using a photoreactive monomer containing a predetermined amount of a monofunctional monomer.

[0250] Example 2, Example 5 and Example 6 respectively show the test results of hologram recording media manufactured using red dye, green dye and blue dye. Compared with other photosensitive dyes, blue dye generally tends to show lower optical recording characteristics. Taking into account this feature of the blue dye, it is determined that the hologram recording medium according to an embodiment of the present disclosure shows excellent optical recording characteristics and low haze in all red, green and blue regions by controlling the element ratio of fluorine on the surface of the photopolymer layer within the above range.

[0251] On the other hand, in Comparative Examples 1 and 2, no or a small amount of monofunctional monomer was used, and the element ratio of fluorine on the surface of the photopolymer layer exceeded 3 atomic %. As a result, it was confirmed that the hologram recording media of Comparative Examples 1 and 2 exhibited high haze.

[0252] In Comparative Example 3, an excessive amount of monofunctional monomer was used, and the element ratio of fluorine on the surface of the photopolymer layer was less than 0.05 atomic %. As a result, it was determined that the hologram recording medium of Comparative Example 3 exhibited very poor recording characteristics due to decreased crosslinking and increased viscosity.

[0253] In Comparative Example 4, the contents of the polymer matrix and the fluorinated compound increased as the content of the total photoreactive monomer decreased, and the element ratio of fluorine on the surface of the photopolymer layer exceeded 3 atomic %. As a result, it was determined that the hologram recording medium of Comparative Example 4 exhibited a good haze level but exhibited deteriorated recording characteristics.

Claims

1. A hologram recording medium comprising a photopolymer layer comprising a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and an acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorinated compound, wherein the element ratio of fluorine is 0.05 atomic % to 3 atomic % based on the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by chemical analysis electron spectroscopy.

2. The hologram recording medium according to claim 1, wherein an element ratio of fluorine is 0.05 atomic % to 2.9 atomic % based on the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by chemical analysis electron spectroscopy.

3. The hologram recording medium according to claim 1, wherein based on the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by chemical analysis electron spectroscopy, the element ratio of carbon is 50 atomic % to 80 atomic %, the element ratio of oxygen is 15 atomic % to 40 atomic %, and the element ratio of silicon is 0.5 atomic % to 10 atomic %.

4. The hologram recording medium according to claim 1, wherein the siloxane-based polymer comprises a repeating unit represented by the following Chemical Formula 1 and a terminal group represented by the following Chemical Formula 2: [Chemical formula 1] in, In Chemical Formula 1, Plural R 1 and R 2 are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and n is an integer from 1 to 10,000, [Chemical formula 2] Wherein, in Chemical Formula 2, Plural R 11 To R 13 are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and R is selected from at least one repeating unit among the repeating units represented by Chemical Formula 1 and any one terminal group among the terminal groups represented by Chemical Formula 2. 1 , R 2 and R 11 To R 13 At least one of them is hydrogen. 5 . The hologram recording medium according to claim 1 , wherein the acrylic polyol is a polymer in which a hydroxyl group is bonded to a main chain or a side chain of an acrylate-based polymer. 6 . The hologram recording medium according to claim 1 , wherein a molar ratio of a silane functional group of the siloxane-based polymer to a hydroxyl group of the acrylic polyol is 1.5 to 4. 7 .

7. The hologram recording medium according to claim 1, wherein the photoreactive monomer includes a monofunctional monomer and a polyfunctional monomer. 8 . The hologram recording medium according to claim 7 , wherein the monofunctional monomer is contained in an amount of 30 wt % to 68 wt % based on the total weight of the photoreactive monomer.

9. The 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. The hologram recording medium according to claim 1, wherein the photoreactive monomer comprises at least one multifunctional monomer selected from the group consisting of bisphenol A (ethylene oxide) 2至10 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 . The hologram recording medium according to claim 1 , wherein the photoreactive monomer is contained in an amount of 50 parts by weight to 300 parts by weight based on 100 parts by weight of the polymer matrix.

12. The holographic recording medium of claim 1, wherein the photoinitiator system comprises a photosensitizing dye and a co-initiator.

13. The hologram recording medium according to claim 12, wherein the coinitiator comprises a borate anion represented by the following Chemical Formula 3: [Chemical formula 3] BX 1 X 2 X 3 X 4 in, In chemical formula 3, X 1 To X 4 are each independently an 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, each of which is substituted or unsubstituted, provided that X 1 To X 4 At least one of the groups is not an aryl group. 14 . The hologram recording medium according to claim 1 , wherein the fluorinated compound is included in an amount of 20 parts by weight to 200 parts by weight based on 100 parts by weight of the polymer matrix.

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

16. The hologram recording medium according to claim 1, wherein when the notch filter hologram is recorded, a diffraction efficiency is 80% or more.

17. The hologram recording medium according to claim 1, wherein a haze is 2% or less.

18. A method for preparing a hologram recording medium, comprising the steps of: applying a photopolymer composition to form a photopolymer layer, wherein the photopolymer composition comprises a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and an acrylic polyol, or a precursor thereof; A fluorinated compound; a photoreactive monomer; and a photoinitiator system; as well as irradiating a coherent laser onto a predetermined area of ​​the photopolymer layer and selectively polymerizing the photoreactive monomer contained in the photopolymer layer to record optical information, wherein the element ratio of fluorine is 0.05 atomic % to 3 atomic % based on the total amount of carbon, oxygen, fluorine and silicon atoms on the surface of the photopolymer layer determined by chemical analysis electron spectroscopy.

19. An optical element comprising the hologram recording medium according to claim 1.

Images