Hologram recording medium, method for manufacturing the same, and optical element including the same

Abstract

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

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2023 - 0076829 filed on June 15, 2023, and Korean Patent Application No. 10 - 2024 - 0068785 filed on May 27, 2024, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference.

[0002] This application relates to a hologram recording medium, a method for manufacturing the same, and an optical element including the same.

Background Art

[0003] A hologram recording medium records information by changing the refractive index in a holographic recording layer through an exposure process, and reads the difference in the refractive index thus recorded to reproduce the information.

[0004] In relation to this, a photopolymer composition can be used for manufacturing holograms. A photopolymer can easily store an optical interference pattern as a hologram by photopolymerization of a photo - reactive monomer. Therefore, photopolymers can be used in various fields such as smart devices like mobile devices, components of wearable displays, vehicle supplies (e.g., head - up displays), holographic fingerprint recognition systems, optical lenses, mirrors, deflecting mirrors, filters, diffusing screens, diffractive members, light guides, waveguides, projection screens and / or masks, media for optical memory systems and light diffusing plates, optical wavelength dividers, reflective and transmissive color filters.

[0005] Specifically, a photopolymer composition for hologram manufacturing includes a polymer matrix, a photo - reactive monomer, and a photo - initiator system. Then, laser interference light is irradiated onto a photopolymer layer manufactured from such a composition to induce local photopolymerization of the monomer.

[0006] Such a local photopolymerization process causes a refractive index modulation, and such a refractive index modulation generates a diffraction grating. The refractive index modulation value (Δn) is affected by the thickness of the photopolymer layer and the diffraction efficiency (DE), and the angular selectivity becomes wider as the thickness becomes thinner.

[0007] Recently, there has been an increasing demand for the development of materials with high diffraction efficiency and high visibility.

Summary of the Invention

Problems to be Solved by the Invention

[0008] According to an embodiment of the present invention, a hologram recording medium is provided.

[0009] According to another embodiment of the present invention, a method for manufacturing the hologram recording medium is provided.

[0010] According to still another embodiment of the present invention, an optical element including the hologram recording medium is provided.

Means for Solving the Problems

[0011] Hereinafter, a hologram recording medium according to a specific embodiment of the invention, a method for manufacturing the same, and an optical element including the same will be described.

[0012] In this specification, unless otherwise specified, the "hologram recording medium" means a medium (medium or media) capable of recording optical information in the entire visible light range and ultraviolet range (e.g., 300 nm to 1,200 nm) by an exposure process. Therefore, the hologram recording medium in this specification may mean a medium on which optical information has been recorded, or a medium before recording in a state capable of recording optical information. The holograms in this specification may include all visual holograms such as in-line (Gabor) holograms, off-axis holograms, full-aperture transfer holograms, white light transmission holograms ("rainbow holograms"), Denisyuk holograms, off-axis reflection holograms, edge-literature holograms, or holographic stereograms.

[0013] According to one embodiment of the invention, there is provided a hologram recording medium including 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 photopolymer layer containing a fluorine-based compound, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine, and silicon atoms confirmed by Electron Spectroscopy for Chemical Analysis (ESCA) on the surface of the photopolymer layer is 0.05 atomic % to 3 atomic %.

[0014] As a result of research to improve the visibility of the hologram recording medium while maintaining various physical properties of the hologram recording medium at an excellent level, the inventors have confirmed that when the compatibility of the photopolymer composition is improved, the haze of the hologram recording medium produced thereby is reduced and the visibility is improved.

[0015] It was confirmed that as the compatibility of the photopolymer composition improved, the elemental ratio of fluorine on the surface of the photopolymer layer decreased. However, it was confirmed that when the elemental ratio of fluorine on the surface of the photopolymer layer became excessively low, the various physical properties of the hologram recording medium deteriorated. Thus, the present invention was completed through experiments that confirmed that only when the elemental ratio of fluorine on the surface of the photopolymer layer satisfies a specific range, the hologram recording medium has excellent optical recording characteristics, which are the various physical properties thereof, excellent compatibility of the material constituting the photopolymer layer, and can exhibit excellent visibility by having a low haze value.

[0016] Specifically, by using Electron Spectroscopy for Chemical Analysis (ESCA) for chemical analysis, the elemental ratio on the surface of the photopolymer layer can be confirmed. According to the ESCA described in the test examples below, after qualitatively analyzing the elements found on the surface of the sample to be analyzed by a survey scan, a narrow scan can be performed for each of the discovered elements to measure the elemental ratio. The elemental ratio of the photopolymer layer in this specification may be understood as the elemental ratio of the photopolymer layer before recording or the elemental ratio of the photopolymer layer after recording. The elemental ratio of the photopolymer layer before recording and the elemental ratio of the photopolymer layer after recording may be the same as each other within the experimental error range, but in some embodiments, they may be different from each other. That is, even if the elemental ratio of the photopolymer layer before recording and the elemental ratio after recording are different from each other beyond the error range, if the elemental ratio before or after recording is within the range described above, the intended effects of the hologram recording medium of the above-described embodiment can be exhibited.

[0017] The elemental ratio of fluorine on the surface of the photopolymer layer included in the hologram recording medium of the above-described embodiment is 0.05 atomic % or more, 0.06 atomic % or more, 0.07 atomic % or more, 0.08 atomic % or more, 0.09 atomic % or more, or 0.10 atomic % or more, and may be 3 atomic % or less, 2.9 atomic % or less, 2.8 atomic % or less, or 2.7 atomic % or less.

[0018] The elemental ratio of carbon with respect to the total amount of carbon, oxygen, fluorine, and silicon atoms confirmed by ESCA on the surface of the photopolymer layer is 50 atomic % to 80 atomic %, the elemental ratio of oxygen is 15 atomic % to 40 atomic %, and the elemental ratio of silicon may be 0.5 atomic % to 10 atomic %.

[0019] Specifically, the elemental ratio of carbon on the surface of the photopolymer layer is 50 atomic % or more, 55 atomic % or more, 60 atomic % or more, 65 atomic % or more, 70 atomic % or more, 71 atomic % or more, or 72 atomic % or more, and may be 80 atomic % or less, 79 atomic % or less, or 78.5 atomic % or less.

[0020] The elemental ratio of oxygen on the surface of the photopolymer layer is 15 atomic % or more, 16 atomic % or more, or 17 atomic % or more, and may be 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.

[0021] The elemental ratio of silicon on the surface of the photopolymer layer is 0.5 atomic % or more, 1.0 atomic % or more, or 1.2 atomic % or more, and may be 10 atomic % or less, 9 atomic % or less, or 8 atomic % or less.

[0022] The elemental ratios of carbon, oxygen, fluorine, and silicon are percentages (atomic %) with respect to the total amount of carbon, oxygen, fluorine, and silicon atoms confirmed by ESCA on the surface of the photopolymer layer.

[0023] By showing the above-described elemental composition ratio, the photopolymer layer can have excellent optical recording characteristics, low haze, and excellent visibility. In particular, if the elemental ratio of fluorine is less than the above range, the optical recording characteristics may deteriorate, and if the elemental ratio of fluorine exceeds the above range, the haze may increase and the visibility may decrease.

[0024] The hologram recording medium of the above embodiment includes 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 photopolymer layer containing a fluorine-based compound.

[0025] The photopolymer layer may be a photopolymer layer in a pre-recording state capable of recording optical information, or may be a photopolymer layer in a state where optical information has been recorded.

[0026] The photopolymer layer in a state where optical information is recorded can be manufactured by irradiating the photopolymer layer before recording with object light and reference light. When the photopolymer layer before recording is irradiated with object light and reference light, in the cancellation interference region, the photoinitiator system exists in an inactive state depending on the interference length of the object light and the reference light, so the photopolymerization of the photoreactive monomer does not occur. In the reinforcement interference region, the photopolymerization of the photoreactive monomer occurs due to the activated photoinitiator system. In the reinforcement interference region, as the photoreactive monomer is continuously consumed, a concentration difference occurs between the photoreactive monomers in the cancellation interference region and the reinforcement interference region. As a result, the photoreactive monomer in the cancellation interference region diffuses into the reinforcement interference region. At this time, the fluorine-based compound of the plasticizer moves in the direction opposite to that of the photoreactive monomer. Since the photoreactive monomer and the photopolymer formed therefrom have a higher refractive index than the polymer matrix and the fluorine-based compound, a spatial refractive index change occurs in the photopolymer layer, and a grating is generated by such a spatial refractive index modulation occurring in the photopolymer layer. Such a grating plane serves as a reflecting surface that reflects incident light due to the difference in refractive index. After hologram recording, when light of the wavelength at the time of recording in the direction of the reference light is incident, it satisfies the Bragg condition, and the light diffracts in the direction of the light of the original object to reproduce the hologram optical information.

[0027] Therefore, if the photopolymer layer is in the state before recording, the photopolymer layer may contain the photoreactive monomer, the photoinitiator system, and the fluorine-based compound randomly dispersed in the polymer matrix.

[0028] On the other hand, if the photopolymer layer is in a state where optical information is recorded, the photopolymer layer may contain a polymer matrix, a photopolymer distributed so as to form a grating, and a fluorine-based compound.

[0029] The photopolymer layer is formed from a photopolymer composition containing a siloxane-based polymer containing a silane functional group and an acrylic polyol crosslinked and formed polymer matrix and its precursor; a fluorine-based compound; a photoreactive monomer; and a photoinitiator system.

[0030] 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 obtained by crosslinking an acrylic polyol with a siloxane-based polymer containing a silane functional group. More specifically, the hydroxy group of the acrylic polyol can form a crosslinking bond with the silane functional group of the siloxane-based polymer through a hydrosilylation reaction. The hydrosilylation reaction can be rapidly carried out even at a relatively low temperature (for example, a temperature of about 60 °C) under a Pt-based catalyst. Therefore, by adopting a polymer matrix that can be rapidly crosslinked even at a relatively low temperature as a support, the manufacturing efficiency and productivity of the hologram recording medium can be improved.

[0031] The polymer matrix can enhance the mobility of components (such as a photoreactive monomer or a plasticizer, etc.) contained in the photopolymer layer by the flexible main chain of the siloxane-based polymer. In addition, the siloxane bond excellent in heat resistance and moisture-heat resistance characteristics can easily ensure the reliability of the photopolymer layer in which optical information is recorded and the hologram recording medium containing the same.

[0032] The polymer matrix can have a relatively low refractive index, and thereby can play a role in enhancing the refractive index modulation of the photopolymer layer. For example, the upper limit of the refractive index of the polymer matrix may be 1.53 or less, 1.52 or less, 1.51 or less, 1.50 or less, or 1.49 or less. And the lower limit of the refractive index of the polymer matrix may be, for example, 1.40 or more, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more. In this specification, the "refractive index" may be a value measured with an Abbe refractometer at 25 °C.

[0033] The photo-polymer layer includes a polymer matrix formed by cross-linking a siloxane-based polymer containing the above-described silane functional group and an acrylic polyol, and may include a polymer matrix precursor that is partially uncross-linked. At this time, the polymer matrix precursor may mean a siloxane-based polymer, an acrylic polyol, and a Pt-based catalyst.

[0034] The siloxane-based polymer may include, for example, a repeating unit represented by the following Chemical Formula 1 (Formula 1) and a terminal group represented by the following Chemical Formula 2 (Formula 2).

[0035]

Chemical Formula

[0036] In Chemical Formula 1, a plurality of R 1 and R 2 are the same as or different from each other and are each independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms, n is an integer of 1 to 10,000,

[0037]

Chemical Formula

[0038] In Chemical Formula 2, a plurality of R 11 to R 13 are the same as or different from each other and are each independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms, at least one of the R 1 , R 2 and R 11 to R 13 of at least one of the terminal groups of the repeating unit represented by Chemical Formula 1 and the terminal group represented by Chemical Formula 2 is hydrogen.

[0039] In Chemical Formula 2, -(O)- means that when Si of the terminal group represented by Chemical Formula 2 binds to the repeating unit represented by Chemical Formula 1, it binds via oxygen (O) or binds directly without oxygen (O).

[0040] As used herein, an "alkyl group" may be a straight-chain, branched-chain, or cyclic alkyl group. By way of non-limiting example, as used herein, an "alkyl group" includes methyl, ethyl, propyl (e.g., n-propyl, isopropyl, etc.), butyl (e.g., n-butyl, isobutyl, tert-butyl, sec-butyl, cyclobutyl, etc.), pentyl (e.g., n-pentyl, isopentyl, neopentyl, tert-pentyl, 1,1-dimethyl-propyl, 1-ethyl-propyl, 1-methyl-butyl, cyclopentyl, etc.), hexyl (e.g., n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methylpentyl, 3,3-dimethylbutyl, 1-ethyl-butyl, 2-ethylbutyl, cyclopentylmethyl, cyclohexyl, etc.), heptyl (e.g., n-heptyl, 1-methylhexyl, 4-methylhexyl, 5-methylhexyl, cyclohexylmethyl, etc.), octyl (e.g., n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, etc.), nonyl (e.g., n-nonyl, 2,2-dimethylheptyl, etc.), and the like.

[0041] As an example, R in Chemical Formulas 1 and 2 1 , R 2 and R 11 ~R 13 are methyl or hydrogen, and at least two of the plurality of R 1 , R 2 and R 11 ~R 13 may be hydrogen. More specifically, as the siloxane polymer, R 1 and R 2 in Chemical Formula 1 are methyl and hydrogen, respectively, and R 11 ~R 13A compound in which each is independently methyl or hydrogen (for example, polymethylhydrosiloxane having a trimethylsilyl group or a dimethylhydrosilyl group as a terminal group); part of R in the chemical formula 1 1 and R 2 are each methyl and hydrogen, and the remaining R 1 and R 2 are all methyl, and R in the chemical formula 2 11 ~R 13 are each independently methyl or hydrogen (for example, poly(dimethylsiloxane-co-methylhydrosiloxane) having a trimethylsilyl group or a dimethylhydrosilyl group as a terminal group); or R in the chemical formula 1 1 and R 2 are all methyl, and at least one of R in the chemical formula 2 11 ~R 13 is hydrogen and the rest are each independently methyl or hydrogen (for example, polydimethylsiloxane in which one or all of the terminal groups are dimethylhydrosilyl groups) may also be used.

[0042] The siloxane compound can have a number average molecular weight (Mn) in the range of 200 to 4,000 as an example. Specifically, the lower limit of the number average molecular weight of the siloxane polymer may be, for example, 200 or more, 250 or more, 300 or more, or 350 or more, and the upper limit may be, for example, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less, 1,500 or less, or 1,000 or less. When the number average molecular weight of the siloxane polymer satisfies the above range, problems such as the matrix crosslinking degree becoming low while the siloxane polymer volatilizes during the crosslinking process with an acrylic polyol carried out at room temperature or a higher temperature, or the siloxane polymer having poor compatibility with the components of other photopolymer layers and phase separation occurring with such components are prevented, so that the hologram recording medium can exhibit excellent optical recording characteristics and moisture and heat resistance.

[0043] The number average molecular weight means the number average molecular weight in terms of polystyrene (unit: g / mol) measured by the GPC method. In the process of measuring the number average molecular weight in terms of polystyrene measured by the GPC method, commonly known analytical instruments, detectors such as a refractive index detector, and analytical columns can be used, and the usually applied temperature conditions, solvents, and flow rates can be applied. Specific examples of the measurement conditions include a temperature of 30 °C, a tetrahydrofuran solvent, and a flow rate of 1 mL / min.

[0044] The equivalent weight of the silane functional group (Si-H) of the siloxane-based polymer may be, for example, in the range of 30 g / equivalent to 200 g / equivalent. More specifically, the equivalent weight of the silane functional group (Si-H) of the siloxane-based polymer may be 50 g / equivalent or more, 60 g / equivalent or more, 70 g / equivalent or more, 80 g / equivalent or more, or 90 g / equivalent or more and 180 g / equivalent or less or 150 g / equivalent or less.

[0045] In this specification, "the equivalent weight of a certain functional group" is an abbreviation for the gram equivalent number (also called equivalent weight) expressed in units of g / equivalent, and means the value obtained by dividing the molecular weight (weight average molecular weight, number average molecular weight, etc.) of the molecule or polymer containing the functional group by the number of the functional groups. Therefore, the smaller the equivalent value, the higher the density of the functional group, and the larger the equivalent value, the lower the density of the functional group.

[0046] When the silane functional group equivalent of the siloxane-based polymer satisfies the above range, the polymer matrix has an appropriate crosslinking density and sufficiently serves as a support, the fluidity of the components contained in the photopolymer layer is improved, and there is no problem that the interface of the diffraction grating generated after recording collapses. Even as time passes, the initial refractive index modulation value can be maintained at an excellent level to minimize the decrease in the recording characteristics for optical information.

[0047] The acrylic polyol can mean a polymer in which one or more, specifically two or more hydroxy groups are bonded to the main chain or side chain of an acrylate-based polymer. In the present specification, unless otherwise specified, the term "acrylic" refers to any one or more selected from acryloyl groups, methacryloyl groups, and their derivatives, or a repeating unit formed by their polymerization, etc., and the term "acrylate-based" refers to any one or more selected from acrylates and methacrylates, or a repeating unit formed by their polymerization, etc.

[0048] The acrylic polyol may be a homopolymer of an acrylate-based monomer having a hydroxy group, a copolymer of two or more acrylate-based monomers having a hydroxy group, or a copolymer of an acrylate-based monomer having a hydroxy group and an acrylate-based monomer not having a hydroxy group. In the present specification, unless otherwise specified, the term "copolymer" encompasses all random copolymers, block copolymers, and graft copolymers.

[0049] Examples of the acrylate monomer having a hydroxy group include hydroxyalkyl (meth)acrylate or hydroxyaryl (meth)acrylate. The alkyl is an alkyl having 1 to 30 carbon atoms, and the aryl may be an aryl having 6 to 30 carbon atoms. Examples of the acrylate monomer having no hydroxy group include alkyl (meth)acrylate or aryl (meth)acrylate. The alkyl is an alkyl having 1 to 30 carbon atoms, and the aryl may be an aryl having 6 to 30 carbon atoms. In the present specification, "(meth)acrylate" is a term referring to acrylate and / or methacrylate unless otherwise specified.

[0050] As an example, the acrylic polyol can have a weight average molecular weight (Mw) in the range of 150,000 to 1,000,000. The weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method as described above. The lower limit of the weight average molecular weight may be, for example, 150,000 or more, 200,000 or more, or 250,000 or more. The upper limit of the weight average molecular weight may be, for example, 900,000 or less, 850,000 or less, 800,000 or less, 750,000 or less, 700,000 or less, 650,000 or less, 600,000 or less, 550,000 or less, 500,000 or 450,000 or less. When the weight average molecular weight of the acrylic polyol satisfies the above range, the polymer matrix can sufficiently exhibit the function of the support, and even after the passage of the use time, the decrease in the recording characteristics for optical information is small. Sufficient flexibility is imparted to the polymer matrix to improve the mobility of the components (such as photoreactive monomers or plasticizers) contained in the photopolymer layer, and the decrease in the recording characteristics for optical information can be minimized.

[0051] In order to adjust the crosslinking density of the acrylic polyol by the siloxane polymer to a level advantageous for ensuring the function of the hologram recording medium, the hydroxyl equivalent of the acrylic polyol can be adjusted to an appropriate level.

[0052] Specifically, the hydroxyl group (-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 group (-OH) equivalent of the acrylic polyol may be 600 g / equivalent or more, 700 g / equivalent or more, 800 g / equivalent or more, 900 g / equivalent or more, 1,000 g / equivalent or more, 1,100 g / equivalent or more, 1,200 g / equivalent or more, 1,300 g / equivalent or more, 1,400 g / equivalent or more, 1,500 g / equivalent or more, 1,600 g / equivalent or more, 1,700 g / equivalent or more, or 1,750 g / equivalent or more. And the upper limit of the hydroxyl group (-OH) equivalent of the acrylic polyol may be 2,900 g / equivalent or less, 2,800 g / equivalent or less, 2,700 g / equivalent or less, 2,600 g / equivalent or less, 2,500 g / equivalent or less, 2,400 g / equivalent or less, 2,300 g / equivalent or less, 2,200 g / equivalent or less, 2,100 g / equivalent or less, 2,000 g / equivalent or less, or 1,900 g / equivalent or less.

[0053] When the hydroxyl group (-OH) equivalent of the acrylic polyol satisfies the above range, the polymer matrix has an appropriate crosslinking density and sufficiently plays the role of a support, the fluidity of the components contained in the photopolymer layer is improved, and there is no problem that the boundary surface of the diffraction grating generated after recording collapses. Even as time passes, the initial refractive index modulation value can be maintained at an excellent level, and the decrease in the recording characteristics for optical information can be minimized.

[0054] The acrylic polyol can have a glass transition temperature (Tg) in the range of, for example, -60°C to -10°C. Specifically, the lower limit of the glass transition temperature 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. The upper limit of the glass transition temperature 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. When the glass transition temperature range is satisfied, the glass transition temperature can be lowered without significantly reducing the modulus of the polymer matrix, increasing the mobility (fluidity) of other components in the photopolymer layer, and 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).

[0055] The refractive index of the acrylic polyol may be, for example, 1.40 or more and less than 1.50. Specifically, the lower limit of the refractive index of the acrylic polyol may be, for example, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more. The upper limit of the refractive index of the acrylic polyol may be, for example, 1.49 or less, 1.48 or less, 1.47 or less, 1.46 or less, or 1.45 or less. When the acrylic polyol has a refractive index in the above-mentioned range, it can contribute to increasing the refractive index modulation. The refractive index of the acrylic polyol is a theoretical refractive index and can be calculated using the refractive index of the monomers used in the production of the acrylic polyol (the value measured using an Abbe refractometer at 25°C) and the fraction (molar ratio) of each monomer.

[0056] The acrylic polyol and the siloxane-based polymer may be included such that the molar ratio (SiH / OH) of the silane functional group (Si-H) of the siloxane-based polymer to the hydroxy group (-OH) of the acrylic polyol is 1.5 to 4.

[0057] The molar ratio of the silane functional groups of the siloxane-based polymer to the hydroxy groups of the acrylic polyol (hereinafter abbreviated as the molar ratio of SiH / OH) can be calculated from the weights of the respective polymers and the number of moles of the functional groups confirmed from the functional group equivalents of the respective polymers.

[0058] Specifically, the silane functional group equivalent of the siloxane-based polymer is the 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 hydroxy group equivalent of the acrylic polyol is the value obtained by dividing the molecular weight (e.g., weight average molecular weight) of the acrylic polyol by the number of hydroxy functional groups per molecule. Therefore, when 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 groups can be confirmed, and when the weight of the acrylic polyol is divided by the hydroxy group equivalent of the acrylic polyol, the number of moles of the hydroxy groups can be confirmed. More specifically, taking Example 1 described later as an example, when the weight (2.5 g) of the siloxane-based polymer used in Example 1 is divided by the silane functional group equivalent (103 g / equivalent) of the siloxane-based polymer used in Example 1, the number of moles of the silane functional groups (0.024 mol) is calculated, and when the weight (21.5 g) of the acrylic polyol used in Example 1 is divided by the hydroxy group equivalent (1802 g / equivalent) of the acrylic polyol used in Example 1, the number of moles of the hydroxy groups (0.012 mol) is calculated. It is confirmed that when the number of moles of the silane functional groups (0.024 mol) calculated in this way is divided by the number of moles of the hydroxy groups (0.012 mol), the molar ratio of SiH / OH is calculated to be 2.

[0059] The lower limit of the molar ratio of SiH / OH may be, for example, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, or 2.0 or more. The upper limit of the molar ratio of SiH / OH 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 range of the molar ratio of SiH / OH is satisfied, the polymer matrix is cross-linked at an appropriate cross-linking density, improving the fluidity of components for recording (such as photoreactive monomers and plasticizers, etc.) to ensure excellent optical recording characteristics. Even when placed in a high-temperature / high-humidity environment after recording, it can suppress the migration, deformation of components in the photopolymer layer, or the intrusion of moisture, etc. into the photopolymer layer, showing excellent moisture and heat resistance, etc., and can show transparent optical characteristics.

[0060] The Pt-based catalyst may be, for example, Karstedt catalyst (Karstedt’s catalyst), etc. The Pt-based catalyst may be contained in an amount of 0.01 parts by weight to 2 parts by weight based on 100 parts by weight of the acrylic polyol. Specifically, the Pt-based catalyst may be contained, for example, in an amount of 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 contained, for example, in an amount of 1.5 parts by weight or less, 1.0 parts by weight or less, 0.5 parts by weight or less, 0.3 parts by weight or less, 0.2 parts by weight or less, 0.15 parts by weight or less, 0.14 parts by weight or less, 0.13 parts by weight or less, or 0.12 parts by weight or less based on 100 parts by weight of the acrylic polyol. When the Pt-based catalyst is used in the above-described content, the polymer matrix is cross-linked at an appropriate cross-linking density and can exhibit the desired optical recording characteristics.

[0061] The polymer matrix precursor may additionally contain, if necessary, in addition to the Pt-based catalyst, a Rhodium-based, Iridium-based, Rhenium-based, Molybdenum-based, Iron-based, Nickel-based, alkali metal or alkaline earth metal-based, Lewis acids-based or Carbene-based non-metal catalyst, etc.

[0062] On the other hand, in the hologram recording medium of the above-described embodiment, object light and reference light can be irradiated onto the photopolymer layer to record optical information. Due to the interference length of such object light and reference light, photopolymerization of the photoreactive monomer does not occur in the cancellation interference region, while photopolymerization of the photoreactive monomer occurs in the reinforcement interference region. Due to the continuous consumption of the photoreactive monomer in the reinforcement interference region, a concentration difference occurs between the photoreactive monomers in the cancellation interference region and the reinforcement interference region. As a result, the photoreactive monomer in the cancellation interference region diffuses into the reinforcement interference region. A diffraction grating is generated by the refractive index modulation thus generated.

[0063] Therefore, the photoreactive monomer can include a compound having a refractive index higher than that of the polymer matrix in order to realize the above-described refractive index modulation. However, not all photoreactive monomers are limited to having a refractive index higher than that of the polymer matrix, and at least some photoreactive monomers can have a refractive index higher than that of the polymer matrix so as to realize a high refractive index modulation value. As an example, the photoreactive monomer can include monomers having a refractive index of 1.50 or more, 1.51 or more, 1.52 or more, 1.53 or more, 1.54 or more, 1.55 or more, 1.56 or more, 1.57 or more, 1.58 or more, 1.59 or more, or 1.60 or more. The upper limit of the refractive index of the monomer contained in the photoreactive monomer is not particularly limited, and may be, for example, 1.70 or less.

[0064] In the hologram recording medium of the above-described embodiment, the photoreactive monomer may include a monofunctional monomer having one photoreactive functional group and a polyfunctional monomer having two or more photoreactive functional groups. At this time, the photoreactive functional group may be, for example, a (meth)acryloyl group, a vinyl group, or a thiol group. More specifically, the photoreactive functional group may be a (meth)acryloyl group.

[0065] The ratio of the monofunctional monomer in the photoreactive monomer is closely related to the compatibility of the materials constituting the photopolymer layer. Specifically, the weight ratio of the monofunctional monomer to the total weight of the photoreactive monomer can be adjusted to 30 wt% to 68 wt%. More specifically, the weight ratio of the monofunctional monomer to the total weight of the photoreactive monomer may be, for example, 30 wt% or more, 31 wt% or more, 32 wt% or more, 33 wt% or more, 34 wt% or more, 35 wt% or more, 36 wt% or more, 37 wt% or more, 38 wt% or more, 39 wt% or more, 40 wt% or more, 41 wt% or more, 42 wt% or more, 43 wt% or more, 44 wt% or more, or 45 wt% or more. The weight ratio of the monofunctional monomer to the total weight of the photoreactive monomer may be, for example, 68 wt% or less, 67 wt% or less, 66 wt% or less, 65 wt% or less, 64 wt% or less, or 63 wt% or less. When the weight ratio of the monofunctional monomer is less than the above range, the compatibility of the materials constituting the photopolymer layer may be poor, the elemental ratio of fluorine on the surface of the photopolymer layer may increase, and the haze of the hologram recording medium may increase. Also, when the weight ratio of the monofunctional monomer exceeds the above range, the crosslinking degree of the photopolymer layer may decrease, the tackiness may increase, and the optical recording characteristics may deteriorate.

[0066] As the monofunctional monomer, a monofunctional (meth)acrylate having a molecular weight of 85 to 500 can be included. Specifically, as the monofunctional monomer, for example, benzyl (meth)acrylate (M1182 of Miwon Co., refractive index 1.5140), benzyl 2-phenylacrylate, phenoxybenzyl (meth)acrylate (M1122 of Miwon Co., refractive index 1.565), phenol (ethylene oxide) (meth)acrylate (phenol(EO)(meth)acrylate; M140 of Miwon Co., refractive index 1.516), phenol (ethylene oxide) 2 (meth)acrylate (phenol(EO)2(meth)acrylate; M142 of Miwon Co., refractive index 1.510), O-phenylphenol (ethylene oxide) (meth)acrylate (O-phenylphenol(EO)(meth)acrylate; M1142 of Miwon Co., refractive index 1.577), phenylthioethyl (meth)acrylate (M1162 of Miwon Co., refractive index 1.560), and biphenylmethyl (meth)acrylate, and one or more selected from the group consisting of these can be included.

[0067] The polyfunctional monomer is, for example, bisphenol A (ethylene oxide) 2~10 di(meth)acrylate (bisphenol A(EO) 2~10(Meth)acrylate; M240 of Miwon Co., refractive index 1.537, M241 refractive index 1.529, M244 refractive index 1.545, M245 refractive index 1.537, M249 refractive index 1.542, M2100 refractive index 1.516, M2101 refractive index 1.512), bisphenol A epoxy di(meth)acrylate (PE210 of Miwon Co., refractive index 1.557, PE2120A refractive index 1.533, PE2120B refractive index 1.534, PE2020C refractive index 1.539, PE2120S refractive index 1.556), bisfluorenyl (meth)acrylate (HR6022 of Miwon Co., refractive index 1.600, HR6040 refractive index 1.600, HR6042 refractive index 1.600), modified bisphenol fluorenyl (meth)acrylate (HR6060 of Miwon Co., refractive index 1.584, HR6100 refractive index 1.562, HR6200 refractive index 1.530), tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate (M370 of Miwon Co., refractive index 1.508), phenol novolac epoxy (meth)acrylate (SC6300 of Miwon Co., refractive index 1.525) and cresol novolac epoxy (meth)acrylate (SC6400 of Miwon Co., refractive index 1.522, SC6400C refractive index 1.522), and may contain one or more selected from the group consisting of them.

[0068] The photopolymer layer can contain 50 to 300 parts by weight of a photoreactive monomer with respect to 100 parts by weight of the polymer matrix. The lower limit of the content of the photoreactive monomer may be, for example, 50 parts by weight or more, 70 parts by weight or more, 100 parts by weight or more, or 110 parts by weight or more. The upper limit of the content of the photoreactive monomer may be, for example, 300 parts by weight or less, 290 parts by weight or less, 280 parts by weight or less, or 270 parts by weight or less.

[0069] At this time, the content of the reference polymer matrix means the combined content (weight) of the acrylic polyol and the siloxane polymer that form the matrix.

[0070] When the above range is satisfied, a photopolymer layer exhibiting excellent optical recording characteristics, heat resistance, heat and humidity resistance, and high transparency can be provided.

[0071] The photopolymer layer contains a photoinitiator system. The photoinitiator system can mean a combination of a photoinitiator or photosensitizer that enables polymerization to be initiated by light and a coinitiator.

[0072] The photopolymer layer can contain a photosensitizer and a coinitiator as the photoinitiator system.

[0073] As the photosensitizer, for example, a photosensitive dye can be used. Specifically, as the photosensitive dye, for example, a silicon rhodamine compound, a sulfonium derivative of ceramidonin, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose bengal, thionine, basic yellow, Pinacyanol chloride, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, Quinaldine Red, crystal violet, Brilliant Green, Astrazon orange G, darrow red, pyronin Y, basic red 29, pyrylium iodide, Safranin O, cyanine, methylene blue, Azure A, and BODIPY, one or more selected from the group consisting of can be used. As the cyanine dye, for example, Cy3 and Cy5 (H-Nu640, spectra) can be used.

[0074] The photo-polymer layer can contain the photosensitive dye in the range of 0.01 to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the photosensitive dye may be, for example, 0.02 parts by weight or more, 0.03 parts by weight or more, or 0.05 parts by weight or more. The upper limit of the content of the photosensitive dye may be, for example, 5 parts by weight or less. When the above range is satisfied, it shows an appropriate polymerization reaction rate and is advantageous for ensuring the desired optical recording characteristics.

[0075] The co-initiator may be an electron donor, an electron acceptor, or a mixture thereof.

[0076] As an example, the photo-polymer composition of the above embodiment can contain an electron donor as the co-initiator. The electron donor can contain, for example, a borate anion represented by the following Chemical Formula 3 (Formula 3).

[0077] [Chemical Formula]

[0078] In Chemical Formula 3, X 1 ~X 4 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, and at least one of X 1 ~X 4 is not an aryl group.

[0079] When the alkyl group having 1 to 20 carbon atoms, alkenyl group having 2 to 20 carbon atoms, aryl group having 6 to 30 carbon atoms, arylalkyl group having 7 to 30 carbon atoms, alkylaryl group having 7 to 30 carbon atoms, or allyl group is substituted, it may be substituted with one or more selected from the group consisting of halogen, vinyl group, haloalkyl group having 1 to 5 carbon atoms, and alkoxy group having 1 to 5 carbon atoms.

[0080] Specifically, X 1 ~X 3 is each independently phenyl, methylphenyl, naphthyl or methylnaphthyl which is substituted or unsubstituted with one or more substituents selected from the group consisting of halogen, vinyl group, trifluoromethyl group and methoxy group, and X 4 may be a straight-chain alkyl group having 1 to 12 carbon atoms.

[0081] More specifically, the borate anion represented by the chemical formula 3 may be, for example, one or more selected from the group consisting of borate anions represented by the following chemical formula 3-1 (Chemical Formula 4) and chemical formula 3-2 (Chemical Formula 5).

[0082]

Chemical Formula

[0083] In the chemical formula 3-1, R 102 are each independently methyl or halogen, R 103 are each independently hydrogen, methyl or halogen and, when the adjacent R 102 is methyl, it is halogen, X 4’ is a straight-chain alkyl group having 1 to 12 carbon atoms.

[0084]

Chemical Formula

[0085] In the formula (3-2), R 106 each independently represents hydrogen, methyl or halogen, X 4” is a linear alkyl group having 1 to 12 carbon atoms.

[0086] In the formula (4-2), R 106 each independently represents hydrogen, methyl or halogen, and at least one of them may be halogen.

[0087] When using the borate anions represented by the following formula (3-1) and formula (3-2) as the electron donor, excellent heat resistance can be ensured even before recording.

[0088] In the formula (3-1) and (3-2), the halogen may be fluorine or chlorine. Among them, in the case of chlorine, more excellent heat resistance can be ensured.

[0089] The cation combined with the borate anion does not absorb light, and may be one or more cations selected from the group consisting of alkali metal cations, quaternary ammonium cations and nitrogen-containing heterocyclic cations.

[0090] The alkali metal cation may be, for example, one or more selected from the group consisting of lithium, sodium, potassium, rubidium and cesium.

[0091] 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.

[0092] Specifically, the quaternary ammonium cation may be a cation represented by the following formula (3-3) (Chemical formula 6).

[0093] [Chemical formula]

[0094] In the chemical formula 3-3, Y 1 ~Y 4 Among them, two substituents may or may not be linked to each other to form an aliphatic ring having 4 to 10 carbon atoms. Y that does not form an aliphatic ring 1 ~Y 4 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond (for example, -CH2CH2-O-CO-CH2CH2CH3, etc.), and Y 1 ~Y 4 Those in which all are methyl groups or those in which two or more substituents are alkyl groups having 16 or more carbon atoms are excluded.

[0095] In the chemical formula 3-3, Y 1 ~Y 4 When all are methyl groups or two or more substituents are alkyl groups having 16 or more carbon atoms, the electron donor may not dissolve well in the photopolymer composition and may not exhibit the desired optical recording characteristics.

[0096] Specifically, two of the substituents of Y 1 ~Y 4 can be linked to each other to form piperidine or pyrrolidine.

[0097] The substituents of the aforementioned Y 1 ~Y 4 that do not form 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, the aforementioned Y 1 ~Y 4Among them, the substituents that do not form an aliphatic ring may each independently be a methyl group, a butyl group, a hexadecyl group, a hentriacontyl group, a phenyl group or a benzyl group.

[0098] The nitrogen-containing heterocyclic cation may be a heteroaromatic ring cation containing one or more nitrogens. Examples of such heteroaromatic ring cations include cations of pyrrole, pyrazole, imidazole or pyridine, and the hydrogens thereof may be substituted or unsubstituted.

[0099] As an example, the nitrogen-containing heterocyclic cation may be a cation represented by the following Chemical Formula 3-4 (Chemical Formula 7).

[0100] [Chemical Formula]

[0101] In the Chemical Formula 3-4, R 107 , R 109 and R 110 are each independently hydrogen, an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms or an alkyl group having 2 to 40 carbon atoms linked via an ester bond (for example, -CH2CH2-O-CO-CH2CH2CH3, etc.), R 108 and R 111 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms or an alkyl group having 2 to 40 carbon atoms linked via an ester bond (for example, -CH2CH2-O-CO-CH2CH2CH3, etc.).

[0102] 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 R110 may each independently be hydrogen or a phenyl group.

[0103] Specifically, said R 108 and R 111 may be a linear alkyl group having 1 to 40 carbon atoms or an arylalkyl group having 6 to 40 carbon atoms. More specifically, said R 108 and R 111 may be a hexadecyl group or a benzyl group.

[0104] The cation combined with the borate anion may include, for example, one or more selected from the group consisting of a tetrabutylammonium cation, a hexadecyldimethylbenzylammonium cation, a hentriacontyldimethylbenzylammonium cation, a hexadecylbenzylpiperidinium cation, a hexadecylbenzylpyrrolidinium cation, a 1-hexadecyl-3-benzylimidazolium cation, and a 1,3-dihexadecyl-2-phenylimidazolium cation.

[0105] However, the cation combined with the borate anion is not limited to the above-mentioned cations. When contained alone, even if it shows low solubility, as long as it can show appropriate solubility when mixed with the above-mentioned cations, a part of the above-mentioned cations may be replaced by other cations known in the relevant technical field. As a non-limiting example, a part of the above-mentioned cations may be replaced by 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium or the like.

[0106] As an example, the photopolymer layer can contain an electron acceptor as a co-initiator. The electron acceptor can include, for example, onium salts such as sulfonium salts, iodonium salts; triazine compounds such as tris(trichloromethyl)-1,3,5-triazine, substituted bis(trichloromethyl)-1,3,5-triazine; or mixtures thereof.

[0107] As an example, the electron acceptor can include (4-(octyloxy)phenyl)(phenyl)iodonium salt as an iodonium salt, or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine as a triazine compound. As the electron acceptor, for example, commercially available H-Nu254 (Spectra) or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine (TCI) can be used.

[0108] The photopolymer layer can contain the co-initiator in the range of 0.05 parts by weight to 10 parts by weight with respect to 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the co-initiator may be, for example, 0.1 part by weight or more, 0.5 part by weight or more, 1 part by weight or more, 1.5 part by weight or more, or 2 parts by weight or more. The upper limit of the content of the co-initiator may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous for ensuring the desired optical recording characteristics by showing an appropriate polymerization reaction rate.

[0109] The photoinitiator system can include an additional photoinitiator to remove the color of the photosensitive dye and react all of the unreacted photoreactive monomers after light irradiation for recording. Examples of the photoinitiator include imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, thioxanthone derivatives, amine derivatives, diazonium salts, sulfonium salts, iodonium salts, sulfonic acid esters, imide sulfonates, dialkyl-4-hydroxy sulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η6-benzene)(η5-cyclopentadienyl)iron(II), benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosyl phthalimide, or mixtures thereof. More specifically, examples of the photoinitiator include 1,3-di(t-butyldioxycarbonyl)benzophenone, 3,3’,4,4’’-tetrakis(t-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-mercapto benzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one,2-diphenylethane-1-one) (Product Name: Irgacure 651 / Manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (1-hydroxy-cyclohexyl-phenyl-ketone) (Product Name: Irgacure 184 / Manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) butanone-1 (2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1) (Product Name: Irgacure 369 / Manufacturer: BASF), bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl) titanium (bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium) (Product Name: Irgacure 784 / Manufacturer: BASF), Ebecryl P-115 (Manufacturer: SK entis), Cyracure UVI-6970, Cyracure UVI-6974, Cyracure UVI-6990 (Manufacturer: Dow Chemical Co. in USA), Irgacure 264, Irgacure 250 (Manufacturer: BASF), CIT-1682 (Manufacturer: Nippon Soda), or a mixture thereof, etc. may be mentioned as examples, but are not limited thereto.,

[0110] The photopolymer layer can contain the photoinitiator in the range of 0.05 parts by weight to 10 parts by weight with respect to 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the photoinitiator may be, for example, 0.1 part by weight or more, 0.5 part by weight or more, 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more. The upper limit of the content of the photoinitiator may be, for example, 5 parts by weight or less. When the above range is satisfied, after recording optical information on the photopolymer layer, the reaction of the photoreactive monomer can be effectively terminated, and the color of the photosensitive dye can be decolorized to provide a transparent hologram recording medium.,

[0111] The photo-polymer layer contains a fluorine-based compound as a plasticizer. The plasticizer can more easily achieve refractive index modulation during the production of the hologram recording medium.

[0112] More specifically, the plasticizer lowers the glass transition temperature of the polymer matrix to improve the fluidity of the photoreactive monomer, has low refractive index and non-reactive properties and is uniformly distributed within the polymer matrix, and when the photoreactive monomer that has not been photopolymerized moves, it can move in the opposite direction and contribute to refractive index modulation.

[0113] Also, the plasticizer can contribute to improving the moldability of the photo-polymer composition.

[0114] In order for the fluorine-based compound to exhibit the functions of the plasticizer described above, it can have a low refractive index of 1.45 or less. Specifically, the upper limit of the refractive index may be, for example, 1.44 or less, 1.43 or less, 1.42 or less, 1.41 or less, 1.40 or less, 1.40 or less, 1.39 or less, 1.38 or less, or 1.37 or less. The lower limit of the refractive index may be, for example, 1.30 or more, 1.31 or more, 1.32 or more, 1.33 or more, 1.34 or more, or 1.35 or more. By using a fluorine-based compound having a refractive index lower than that of the photoreactive monomer described above, the refractive index of the polymer matrix can be made lower, and the refractive index modulation by the photoreactive monomer can be made larger.

[0115] The fluorine-based compound can contain, for example, one or more functional groups selected from the group consisting of an ether group, an ester group, and an amide group, and two or more difluoromethylene groups. More specifically, the fluorine-based compound may be, as an example, a compound containing a repeating unit represented by the following Chemical Formula 4 (Chemical Formula 8).

[0116]

Chemical Formula

[0117] In the above Chemical Formula 4, A plurality of R 31 ~R 34 are each independently hydrogen or fluorine, and at least one of R 31 ~R 34 is fluorine, and m is an integer from 2 to 12.

[0118] More specifically, the fluorine-based compound may be a compound containing 1 to 3 units represented by the following Chemical Formula 4-1 (Chemical Formula 9).

[0119]

Chemical Formula

[0120] In the above Chemical Formula 4-1, R 41 ~R 44 and R 53 ~R 56 are each independently hydrogen or fluorine, and R 45 ~R 52 is fluorine.

[0121] As an example, in the above Chemical Formula 4-1, R 41 , R 42 , R 55 and R 56 are hydrogen, and R 43 ~R 54 is fluorine.

[0122] The fluorine-based compound containing the (repeating) units represented by the above Chemical Formula 4 and Chemical Formula 4-1 is not particularly limited, but it can be capped with an end capping agent widely used in the related technical field. As an example, the terminal of the fluorine-based compound containing the (repeating) units represented by the above Chemical Formula 4 and Chemical Formula 4-1 may be an alkyl group or an alkyl group substituted with one or more alkoxys. As a non-limiting example, when 2-methoxyethoxymethyl chloride is used as the end capping agent, the terminal of the fluorine-based compound containing the (repeating) units represented by the above Chemical Formula 4 and Chemical Formula 4-1 may be a 2-methoxyethoxymethyl group.

[0123] The fluorine-based compound may have a weight average molecular weight of 300 or more. Specifically, the lower limit of the weight average molecular weight of the fluorine-based compound may be, for example, 350 or more, 400 or more, 450 or more, 500 or more, or 550 or more. The upper limit of the weight average molecular weight of the fluorine-based compound may be, for example, 1000 or less, 900 or less, 800 or less, 700 or less, or 600 or less. When considering refractive index modulation, compatibility with other components, problems of elution of the fluorine-based compound, etc., it is preferable to satisfy the range of the weight average molecular weight. At this time, the weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method as described above.

[0124] The photo-polymer layer can contain 20 to 200 parts by weight of the fluorine-based compound with respect to 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the fluorine-based compound may be, for example, 25 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, or 70 parts by weight or more. The upper limit of the content of the fluorine-based compound may be, for example, 190 parts by weight or less, 180 parts by weight or less, 170 parts by weight or less, 160 parts by weight or less, or 155 parts by weight or less. When the above range is satisfied, there are no problems such as the compatibility with the components contained in the photo-polymer layer deteriorating and some of the fluorine-based compounds eluting on the surface of the photo-polymer layer, or the haze deteriorating. A fluorine-based compound having a sufficient low refractive index can exhibit a large refractive index modulation value after recording, which is advantageous for ensuring excellent optical recording characteristics.

[0125] Most of the components of the photo-polymer layer can be said to be a polymer matrix, a photo-reactive monomer, and a fluorine-based compound. Therefore, the elemental composition ratio on the surface of the photo-polymer layer can be controlled by the blending ratio of the polymer matrix, the photo-reactive monomer, and the fluorine-based compound. In order to satisfy the above-described elemental composition ratio, the photo-polymer layer can contain 17% to 38% by weight of the polymer matrix, 38% to 58% by weight of the photo-reactive monomer, and 17% to 38% by weight of the fluorine-based compound with respect to the total weight of the polymer matrix, the photo-reactive monomer, and the fluorine-based compound.

[0126] More specifically, the polymer matrix may contain, 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 may contain, for example, 38% by weight or less, 37% by weight or less, or 36% by weight or less. The photoreactive monomer may contain, 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 may contain, for example, 58% by weight or less, 55% by weight or less, or 53% by weight or less. The fluorine-based compound may contain, for example, 17% by weight or more, 18% by weight or more, 19% by weight or more, or 20% by weight or more. The fluorine-based compound may contain, for example, 38% by weight or less, 35% by weight or less, 33% by weight or less, or 32% by weight or less. A photopolymer layer satisfying the above-described element composition ratios within such a range can be provided.

[0127] The photopolymer layer can additionally contain additives such as a surfactant or an antifoaming agent.

[0128] The photopolymer layer can contain, as the surfactant, a silicone-based surfactant, a fluorine-based surfactant, or a mixture thereof.

[0129] As the silicone surfactant, 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-335, BYK-341v344, BYK-345v346, BYK-348, BYK-354, BYK355, BYK-356, BYK-358, BYK-361, BYK-370, BYK-371, BYK-375, BYK-380, BYK-390, BYK-3550, etc. of BYK Chemie can be used. As the fluorosurfactant, 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, etc. of DIC (DaiNippon Ink&Chemicals) can be used.

[0130] If the photopolymer layer contains a surfactant, it can contain 0.01 part by weight or more, 0.02 part by weight or more, 0.03 part by weight or more, or 0.05 part by weight or more and 5 parts by weight or less or 3 parts by weight or less of the surfactant with respect to 100 parts by weight of the polymer matrix. When the above range is satisfied, excellent adhesiveness and releasability can be imparted to the photopolymer layer to preserve excellent optical recording characteristics.

[0131] The photo-polymer layer may contain a silicone-based reactive additive as an antifoaming agent. As the silicone-based reactive additive, for example, commercially available products such as Tego Rad 2500 can be used. The content of the antifoaming agent can be appropriately adjusted at a level that does not interfere with the functions of the hologram recording medium.

[0132] The photo-polymer layer may be formed from a photo-polymer composition containing a solvent.

[0133] The solvent may be an organic solvent, and as an example, it may be one or more organic solvents selected from the group consisting of ketones, alcohols, acetates, and ethers, but is not limited thereto. Specific examples of such organic solvents include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or isobutyl ketone; alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, or t-butanol; acetates such as ethyl acetate, i-propyl acetate, or polyethylene glycol monomethyl ether acetate; and one or more selected from the group consisting of ethers such as tetrahydrofuran or propylene glycol monomethyl ether.

[0134] The organic solvent may be added at the time when each component contained in the photo-polymer composition is mixed, or may be contained in the photo-polymer composition while being added in a state where each component is dispersed or mixed in the organic solvent.

[0135] The photo-polymer composition can contain a solvent such that the concentration of the solid content is 1 wt% to 90 wt%. Specifically, the photo-polymer composition can contain a solvent such that the concentration of the solid content 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 such a range, the photo-polymer composition exhibits appropriate fluidity, can form a coating film without defects such as streaks, and can form a photo-polymer layer that does not have defects during its drying and curing process and exhibits desired physical properties and surface characteristics.

[0136] Despite having a thin photo-polymer layer, the hologram recording medium of the above-described embodiment is excellent in refractive index modulation, diffraction efficiency, and driving reliability.

[0137] The thickness of the photo-polymer 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 photo-polymer layer may be, for example, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. And the upper limit of the thickness may be, for example, 35 μm or less, 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, or 18 μm or less.

[0138] The hologram recording medium of the above-described embodiment can further include a substrate on at least one surface of the photo-polymer layer. The type of the substrate is not particularly limited, and those known in the related art can be used. For example, substrates such as glass, PET (polyethylene terephthalate), TAC (triacetyl cellulose), PC (polycarbonate), and COP (cycloolefin polymer) can be used.

[0139] The hologram recording medium of the above-described embodiment can have a high diffraction efficiency. As an example, when the hologram recording medium records a Notch filter hologram, it can have a diffraction efficiency of 80% or more. At this time, the thickness of the photopolymer layer may be, for example, 5 μm to 30 μm. Specifically, when a Notch filter hologram is recorded, 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. As an example, when a red dye or a green dye is used as the photosensitive dye and a Notch filter hologram is recorded, the diffraction efficiency may be, for example, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, or 96% or more. Thus, the hologram recording medium of the above-described embodiment can achieve excellent diffraction efficiency even when including a photopolymer layer with a thin thickness. The diffraction efficiency can be measured by the method described in the test example below.

[0140] On the other hand, since the hologram recording medium is used by mixing a component having a low refractive index and a component having a high refractive index for optical property recording, it is likely to have an opaque property due to the compatibility thereof. However, the hologram recording medium of the above-described embodiment can exhibit an optical property of high transparency by controlling the elemental ratio of fluorine on the surface of the photopolymer layer within a specific range.

[0141] As an 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 more. The haze can be measured by the method described in the test example below.

[0142] The hologram recording medium of the above-described embodiment is expected to provide various optical elements with high visibility by exhibiting excellent optical recording characteristics and highly transparent optical characteristics.

[0143] The hologram recording medium of the above-described embodiment is not limited thereto, but may be one on which a reflection hologram or a transmission hologram is recorded.

[0144] On the other hand, according to another embodiment of the invention, a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and an acrylic polyol; a fluorine-based compound; a photoreactive monomer; and a photopolymer composition containing a photoinitiator system are applied to form a photopolymer layer; and irradiating a predetermined region of the photopolymer layer with an interferable laser to selectively polymerize the photoreactive monomer contained in the photopolymer layer to record optical information, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine, and silicon atoms confirmed by electron spectroscopy for chemical analysis (ESCA) on the surface of the photopolymer layer is 0.05 atomic % to 3 atomic %, and a method for manufacturing a hologram recording medium is provided.

[0145] The photopolymer layer having the specific elemental composition ratio of fluorine may be the photopolymer layer included in the hologram recording medium of the above-described embodiment. Since the photopolymer layer has been described in detail above, a detailed description thereof will be omitted here.

[0146] In the step of forming the photopolymer layer, first, a photopolymer composition including the above-described configuration can be manufactured. When manufacturing the photopolymer composition, for mixing of each component, generally known mixers, stirrers, mixers, etc. can be used without any limitation. And 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.

[0147] In the step of forming the photopolymer layer, the prepared photopolymer composition can be applied to form a coating film formed from the photopolymer composition. The coating film can be dried at a temperature of 50 °C or higher, 55 °C or higher, 60 °C or higher, 65 °C or higher, or 70 °C or higher and 120 °C or lower, 110 °C or lower, 100 °C or lower, or 90 °C or lower. Through this process, a hydrosilylation reaction between the hydroxy group of the acrylic polyol remaining without reaction and the silane functional group of the siloxane polymer can be induced to achieve the target crosslink density while maintaining high transparency.

[0148] In the photopolymer layer produced in the step of forming the photopolymer layer, a fluorine-based compound, a photoreactive monomer, a photoinitiator system, additives added as required, etc. may be uniformly dispersed in the crosslinked polymer matrix.

[0149] Thereafter, when the photopolymer layer is irradiated with an interferable laser in the step of recording optical information, polymerization of the photoreactive monomer occurs in the region where constructive interference occurs to form a photopolymer, and polymerization of the photoreactive monomer does not occur or is suppressed in the region where destructive interference occurs, and the photoreactive monomer is present. Then, the unreacted photoreactive monomer diffuses to the photopolymer side where the concentration of the photoreactive monomer is low, causing a refractive index modulation, and a diffraction grating is generated by the refractive index modulation. Thereby, a hologram, that is, optical information, is recorded in the photopolymer layer having the diffraction grating.

[0150] The method for manufacturing the hologram recording medium of the other embodiment can additionally include a step of overall irradiating the photopolymer layer on which optical information is recorded with light for photobleaching after the step of recording optical information.

[0151] In the light bleaching step, ultraviolet rays are irradiated onto the photopolymer layer in which optical information is recorded to terminate the reaction of the photoreactive monomers remaining in the photopolymer layer, and the color of the photosensitive dye can be removed. As an example, in the light bleaching step, ultraviolet rays (UVA) in the region of 320 nm to 400 nm can be irradiated to terminate the reaction of the photoreactive monomers and remove the color of the photosensitive dye.

[0152] On the other hand, according to still another embodiment of the invention, an optical element including the hologram recording medium is provided.

[0153] Specific examples of the optical element include smart devices such as mobile devices, components of wearable displays, vehicle supplies (for example, head up display), holographic fingerprint recognition systems, optical lenses, mirrors, deflection mirrors, filters, diffusion screens, diffractive members, light guides, waveguides, holographic optical elements having the functions of projection screens and / or masks, media of optical memory systems and light diffusing plates, optical wavelength dividers, reflective and transmissive color filters, and the like.

[0154] An example of the optical element including the hologram recording medium includes a hologram display device. The hologram display device includes a light source unit, an input unit, an optical system, and a display unit.

[0155] Specifically, the light source unit is a part that irradiates a laser beam used to provide, record, and reproduce three-dimensional video information of an object in the input unit and the display unit.

[0156] The input unit is a part that pre-inputs three-dimensional video information of an object to be recorded in the display unit. Specifically, three-dimensional information of an object such as the intensity and phase of light for each space can be input into an electrically addressed liquid crystal SLM, and at this time, it is a part where an input beam can be used.

[0157] The optical system may be composed of a mirror, a polarizer, a beam splitter, a beam shutter, a lens, etc. The optical system can distribute a laser beam emitted from the light source unit to an input beam sent to the input unit, a recording beam sent to the display unit, a reference beam, an erasing beam, a reading beam, etc.

[0158] The display unit can receive three-dimensional video information of an object from the input unit, record it on a hologram plate composed of an optically addressed SLM (optically addressed SLM), and reproduce the three-dimensional video of the object. At this time, the three-dimensional video information of the object can be recorded by the interference between the input beam and the reference beam. The three-dimensional video information of the object recorded on the hologram plate can be reproduced as a three-dimensional video by the diffraction pattern generated by the reading beam, and the erasing beam can be used to quickly remove the formed diffraction pattern. On the other hand, the hologram plate can move between the position where the three-dimensional video is input and the position where it is reproduced.

Advantages of the Invention

[0159] The hologram recording medium according to an embodiment of the invention 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 with excellent visibility.

Brief Description of the Drawings

[0160]

Figure 1

Best Mode for Carrying Out the Invention

[0161] Hereinafter, the actions and effects of the invention will be described more specifically through specific examples of the invention. However, this is presented as an example of the invention, and the scope of the invention is not limited in any way thereby.

[0162] In the following production examples, examples, and comparative examples, etc., the content of raw materials, etc. means the content based on solid matter unless otherwise specified.

[0163] Production Example 1: Production of Acrylic Polyol 132 g of butyl acrylate, 420 g of ethyl acrylate, and 48 g of hydroxybutyl acrylate were placed in a 2 L jacketed reactor and diluted with 1200 g of ethyl acetate. The reaction temperature was set at 60°C to 70°C, and stirring was carried out for about 30 minutes to 1 hour. 0.42 g of n-dodecyl mercaptan (n-DDM) was additionally added, and stirring was further carried out for about 30 minutes. Thereafter, 0.24 g of AIBN as a polymerization initiator was added, and polymerization was carried out at the reaction temperature for 4 hours or more until the content of residual acrylate became less than 1%, to produce an acrylate copolymer in which a hydroxy group was located in a branched chain (weight average molecular weight of about 300,000, OH equivalent of about 1802 g / equivalent).

[0164] Production Example 2: Production of Fluorine-based Compound After adding 20.51 g of 2,2’-(oxybis((1,1,2,2-tetrafluoroethane-2,1-diyl)oxy))bis(2,2-difluoroethan-1-ol) to a 1000 mL flask, it was dissolved in 500 g of tetrahydrofuran and 4.40 g of sodium hydroxide (60% dispersion in mineral oil) was carefully added in several portions while stirring at 0 °C. After stirring at 0 °C for 20 minutes, 12.50 mL of 2-methoxyethoxymethyl chloride was gradually added dropwise. When it was confirmed by 1H NMR that all the reactants had been consumed, a liquid product with a purity of 95% or more was obtained in a 98% yield by work-up using dichloromethane. The weight average molecular weight of the produced fluorine-based compound was 586, and the refractive index measured with an Abbe refractometer was 1.361.

[0165] Example 1: Production of Hologram Recording Medium (1) Production of the photopolymer composition First, trimethylsilyl terminated poly(methylhydrosiloxane) (manufactured by Sigma-Aldrich, number average molecular weight: about 390, SiH equivalent about 103 g / equivalent), which is a siloxane-based polymer, and the acrylic polyol produced in Production Example 1 were mixed. The content of the acrylic polyol was 21.5 g, and the siloxane-based polymer was added so that the molar ratio of SiH / OH was 2. In Example 1, 2.5 g of the siloxane-based polymer was added.

[0166] Then, 48 g of a photoreactive monomer in which bisfluorescein acrylate and O-phenylphenol (ethylene oxide) (meth) acrylate (OPPEA) were mixed at a weight ratio of 68:32, 0.2 g of Red dye H-Nu640 (Spectra) as a photosensitive dye, 0.8 g of hexadecyl dimethyl benzyl ammonium tri(p-chlorophenyl) butyl borate as a co-initiator, 0.05 g of H-Nu254 (Spectra), 0.9 g of Irgacure 369 as a photoinitiator, 24 g of the fluorine-based compound produced in Production Example 2 as a plasticizer, and 206 g of methyl isobutyl ketone (MIBK) as a solvent were added, and the mixture was stirred with a paste mixer for about 30 minutes in a light-shielded state. Thereafter, 0.014 g of a Karstedt (Pt-based) catalyst was added for matrix crosslinking to produce a photopolymer composition.

[0167] (2) Production of hologram recording medium The photopolymer composition was coated to a predetermined thickness on a 60-μm-thick TAC substrate using a Mayer bar and dried at 80 °C for 10 minutes. The thickness of the photopolymer layer after drying was about 15 μm.

[0168] A diffraction grating was recorded using the setup as shown in FIG. 1. Specifically, after laminating the produced photopolymer layer on a mirror, when irradiated with a laser, a Notch filter hologram having a periodic refractive index modulation in the thickness direction can be recorded due to the interference between the incident light (L) and the light (L’) reflected by the mirror. In this example, a Notch filter hologram was recorded with an incident angle of 0° (degree). A Notch filter and a Bragg reflector are optical elements that reflect only light of a specific wavelength and have a structure in which two layers with a refractive index difference are periodically laminated repeatedly at a constant thickness.

[0169] Examples 2 to 6 and Comparative Examples 1 to 3: Production of Hologram Recording Medium A holographic recording medium was produced in the same manner as in Example 1, except that the type and ratio of the monofunctional monomer in the photoreactive monomer and the type of the photosensitive dye were varied as described in Table 1 below.

[0170] That is, in the case of Examples 2 and 3, the same monofunctional monomer as in Example 1 was used, but while increasing its ratio to the total content of the photoreactive monomer as described in Table 1 below, at the same time, the ratio of bisfluorenyl diacrylate, which is a polyfunctional monomer, was decreased to produce a photopolymer composition, and a holographic recording medium was produced therefrom.

[0171] In the case of Example 4, a holographic recording medium was produced in the same manner as in Example 2, except that phenoxybenzyl acrylate (PBA) was used as the monofunctional monomer.

[0172] In the case of Example 5, a holographic recording medium was produced in the same manner as in Example 2, except that rhodamine 6G of Green dye was used instead of Red dye as the photosensitive dye.

[0173] In the case of Example 6, a holographic recording medium was produced in the same manner as in Example 2, except that astrazon orange G of Blue dye was used instead of Red dye as the photosensitive dye.

[0174] In the case of Comparative Example 1, a holographic recording medium was produced in the same manner as in Example 1, except that only bisfluorenyl diacrylate, which is a polyfunctional monomer, was used as the photoreactive monomer.

[0175] In the case of Comparative Examples 2 and 3, a holographic recording medium was produced in the same manner as in Example 1, except that while decreasing or increasing the ratio of the monofunctional monomer to the total content of the photoreactive monomer as described in Table 1 below, the ratio of the polyfunctional monomer was controlled by the decreased or increased amount.

[0176]

Table 1

[0177] Comparative Example 4: Production of Hologram Recording Medium A holographic recording medium was produced in the same manner as in Example 1, except that 31.4 g of the acrylic polyol produced in Production Example 1, 3.6 g of the siloxane polymer, 35 g of HR6042 (manufactured by Miwon Co., refractive index 1.60) as a photoreactive monomer, 0.2 g of the compound represented by the following chemical formula a (Chemical Formula 10) as a photosensitive dye, and 30 g of the fluorine-based compound produced in Production Example 2 as a plasticizer were used.

[0178] [Chemical formula]

[0179] Test Example: Performance Evaluation of Hologram Recording Medium (1) Element ratio The elemental ratio of the surface of the sample before recording was analyzed by the method described below.

[0180] Specifically, the sample to be analyzed was fixed on a copper foil with carbon tape, placed on a sample holder, and fixed using a clip. Then, data was obtained using a photoelectron spectrometer (ESCA, model name: K-Alpha+, Thermo Fisher Scientific Inc.) for chemical analysis by the K-Alpha+ standard operation method (SOP-0524-Ok), and the elemental ratio (atomic %) of the sample surface was analyzed using Avantage software (version 5.980).

[0181] The system specifications of the ESCA instrument used are as follows.

[0182] -Base chamber pressure: 1.0X10 -9 mbar -X-ray source: monochromatic Al Kα (1486.6 eV) -X-ray spot size: 400 μm -Mode: CAE (Constant Analyzer Energy) mode -Charge compensation: Flood gun (FG03: 100 μA, 0.5 V)

[0183] For the surface of the as-received sample to be analyzed, an initial survey scan was performed under the following conditions to conduct qualitative analysis, and quantitative analysis was carried out by narrow scan (snap) for each element based on the results of the qualitative analysis. The elemental ratios at three locations per sample were confirmed, and the peak background smart method was applied for quantitative analysis. The binding energy correction of the core level spectrum was based on C 1s (284.8 eV).

[0184] <Survey scan conditions> -Scan range of binding energy: -5 eV to 1350 eV -Step size: 1 eV -Per Point dwell time: 20 ms -Periods: 2 -Pass energy: 200 eV <narrow scan conditions> -Scan range of binding energy: approximately 20 eV -Step size: ~0.16 eV -Per Point dwell time: 1 sec -Periods: 10 - 30 -Pass energy: 150 eV <Etching conditions> -Source: Ar ion -Energy: 6 keV -Cluster size: 75 -Rater size: 1.6 X 1.0 mm 2 -Mode: GCIB

[0185] (2) Diffraction efficiency (DE) The diffraction efficiency (η) was determined by the following formula 1 (Equation 1).

[0186]

Equation

[0187] In the above formula 1, η is the diffraction efficiency, and P D is the output power (mW / cm 2 ) of the diffracted beam of the sample after recording, and P T is the output power (mW / cm 2 ) of the transmitted beam of the sample after recording.

[0188] (3) Haze A 5 cm × 5 cm test piece was prepared from the sample on which the diffraction grating was recorded. The haze of the test piece was measured using a haze meter (HM-150, A light source, Murakami Co., Ltd.) in accordance with JIS K7136. The haze was measured three times in total, and the average value was calculated and defined as the haze value of the sample.

[0189]

Table 2

[0190] Referring to Table 2 above, it is confirmed that the hologram recording medium of the above-described embodiment exhibits excellent optical recording characteristics and low haze by controlling the elemental ratio of fluorine on the surface of the photopolymer layer to 0.05 atomic % to 3 atomic %. This is considered to be the result of improving the compatibility of the photopolymer composition by using a photoreactive monomer containing a monofunctional monomer having a predetermined content.

[0191] Example 2, Example 5, and Example 6 show the test results of hologram recording media manufactured using Red dye, Green dye, and Blue dye, respectively. In the case of Blue dye, it is generally shown to have lower optical recording characteristics compared to other photosensitive dyes. Considering such points, it is confirmed that the hologram recording media of the one embodiment controls the elemental ratio of fluorine on the surface of the photopolymer layer within the above range, and exhibits excellent optical recording characteristics and low haze in all regions of red, green, and blue.

[0192] On the other hand, in Comparative Examples 1 and 2, a monofunctional monomer was not used or was used in a very small amount, and the elemental ratio of fluorine on the surface of the photopolymer layer exceeded 3 atomic %. As a result, the hologram recording media of Comparative Examples 1 and 2 showed high haze.

[0193] In Comparative Example 3, an excessive amount of monofunctional monomer was used, and the ratio of fluorine on the surface of the photopolymer layer was less than 0.05 atomic %. As a result, the hologram recording media of Comparative Example 3 had a reduced crosslinking degree, increased tackiness, and very poor recording characteristics.

[0194] In Comparative Example 4, as the content of the overall photoreactive monomer decreased, the contents of the polymer matrix and the fluorine-based compound increased, and the elemental ratio of fluorine on the surface of the photopolymer layer exceeded 3 atomic %. As a result, the hologram recording media of Comparative Example 4 showed a good level of haze but exhibited reduced recording characteristics.

Claims

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

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

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

4. The siloxane polymer contains a repeating unit represented by the following chemical formula 1 (Chemical Formula 1) and a terminal group represented by the following chemical formula 2 (Chemical Formula 2). 【Chemical 1】 In the chemical formula 1, A plurality of Rs １ and R ２ are the same as or different from each other, and each independently is hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms, n is an integer from 1 to 10,000. ​ In the chemical formula 2, Plural R １１ ~R １３ are the same as or different from each other, and each independently is hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms, R of either one of the terminal groups among at least one repeating unit represented by the above chemical formula (1) and the terminal group represented by the above chemical formula (2) １ , R ２ and R １１ ~R １３ At least one of which is hydrogen, the hologram recording medium according to claim 1.

5. The hologram recording medium according to claim 1, wherein the acrylic polyol is a polymer having a structure in which a hydroxy group is bonded to the main chain or side chain of an acrylate polymer.

6. The hologram recording medium according to claim 1, wherein the molar ratio of the silane functional group of the siloxane polymer to the hydroxy group of the acrylic polyol is 1.5 to 4.

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% by weight to 68% by weight based on the total weight of the photoreactive monomer.

9. The photoreactive monomer includes 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. The hologram recording medium according to claim 1.

10. The photoreactive monomer is bisphenol A (ethylene oxide) ２～１０ The hologram recording medium according to claim 1, comprising one or more polyfunctional monomers selected from the group consisting of di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisfluorenyl 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 hologram recording medium according to claim 1, wherein the photoinitiator system includes a photosensitive dye and a co-initiator.

13. The co-initiator includes a borate anion represented by the following chemical formula 3 (Chemical Formula 3). 【Chemical Formula 3】 In the chemical formula 3, X １ to X ４ are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, and at least one of X １ to X ４ is not an aryl group. The hologram recording medium according to claim 12.

14. The hologram recording medium according to claim 1, wherein the fluorine-based compound is contained 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 contains the polymer matrix in an amount of 17% to 38% by weight, the photoreactive monomer in an amount of 38% to 58% by weight, and the fluorine-based compound in an amount of 17% to 38% by weight, based on the total weight of the polymer matrix, the photoreactive monomer, and the fluorine-based compound.

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

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

18. Applying a photopolymer composition containing a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and an acrylic polyol, a fluorine-based compound, a photoreactive monomer, and a photoinitiator system to form a photopolymer layer; Irradiating a predetermined region of the photopolymer layer with an interferable laser to selectively polymerize the photoreactive monomer contained in the photopolymer layer to record optical information. A method for manufacturing a hologram recording medium, wherein the elemental ratio of fluorine to the total amount of carbon, oxygen, fluorine, and silicon atoms confirmed by photoelectron spectroscopy for chemical analysis on the surface of the photopolymer layer is 0.05 atomic% to 3 atomic%.

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

Images