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

Abstract

The present invention relates to a holographic recording medium, a method for producing the same, and an optical element including the same. The holographic recording medium has a specific element composition ratio, and thus has excellent optical recording properties, excellent durability against heat and moisture, suitable adhesive strength to a transparent adhesive, and high transparency.

Description

[Technical Field]

[0001] [Cross-reference of related applications] This application claims priority rights based on Korean Patent Application No. 10-2022-0146069 dated November 4, 2022, Korean Patent Application No. 10-2022-0146073 dated November 4, 2022, and Korean Patent Application No. 10-2023-0132803 dated October 5, 2023, and all content disclosed in the documents of said Korean Patent Applications is included as part of this Specification.

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

[0003] A hologram recording medium records information by changing the refractive index within the holographic recording layer during the exposure process, and then reproduces the information by reading the difference in refractive index recorded in this way.

[0004] In this regard, photopolymer compositions can be used in the manufacture of holograms. Photopolymers can easily store optical interference patterns as holograms by photopolymerization of photoreactive monomers. Therefore, photopolymers can be used in a variety of fields, such as smart devices like mobile devices, components of wearable displays, automotive accessories (e.g., head-up displays), holographic fingerprint recognition systems, holographic optical elements having the functions of optical lenses, mirrors, deflectors, filters, diffusion screens, diffracting members, light guides, waveguides, projection screens and / or masks, media and light diffusers for optical memory systems, optical wavelength dividers, and reflective and transmissive color filters.

[0005] Specifically, the photopolymer composition for hologram production comprises a polymer matrix, a photoreactive monomer, and a photoinitiator system. A photopolymer layer produced from such a composition is then irradiated with laser interference light to induce localized photopolymerization of the monomer.

[0006] Such localized photopolymerization processes lead to refractive index modulation, which in turn generates a diffraction grating. The refractive index modulation value (Δn) is influenced by the thickness of the photopolymer layer and the diffraction efficiency (DE), and the angular selectivity widens as the thickness decreases.

[0007] Recently, there has been a growing demand for materials that offer high diffraction efficiency and can stably maintain holograms. As a result, various attempts are being made to manufacture holographic recording media that are thin yet possess high diffraction efficiency and refractive index modulation values.

[0008] On the other hand, when holographic recording media are used as optical elements in applications such as mobile devices and automotive accessories (e.g., head-up displays), they are exposed to high-temperature and high-humidity environments. In this case, deformation of the diffraction grating occurs, causing image distortion or preventing the recording media from performing their intended function. Therefore, there is a need to develop photopolymer layers and holographic recording media containing them that exhibit minimal deformation of the diffraction grating despite the heat and moisture of the operating environment, and that offer superior reliability. [Overview of the project] [Problems that the invention aims to solve]

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

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

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

[0012] The following describes a holographic recording medium, a method for manufacturing the same, and an optical element including the same, according to specific embodiments of the invention.

[0013] In this specification, "hologram recording medium" means a medium (or media) capable of recording optical information in the entire visible light range and ultraviolet range (e.g., 300 nm to 1,200 nm) through an exposure process, unless otherwise specified. Therefore, the hologram recording medium in this specification may mean a medium on which optical information has been recorded, or a pre-recording medium in a state capable of recording optical information. The holograms in this specification may include all visual holograms, such as inline (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.

[0014] According to one embodiment of the invention, a holographic recording medium is provided comprising a polymer matrix or precursor thereof formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a photopolymer layer containing a fluorine compound, wherein the elemental ratio of carbon is 50 to 70 atoms, the elemental ratio of nitrogen is 0.01 to 2 atoms, the elemental ratio of oxygen is 15 to 30 atoms, the elemental ratio of fluorine is 3 to 12 atoms, and the elemental ratio of silicon is 3 to 15 atoms, relative to the total amount of carbon, nitrogen, oxygen, fluorine, and silicon atoms confirmed by photoelectron spectroscopy on the surface of the photopolymer layer.

[0015] The holographic recording medium of the above embodiment, by including a photopolymer layer having a specific elemental composition ratio, possesses excellent properties of optical recording, as well as durability against heat and moisture, adhesion to OCA, and transparency.

[0016] Specifically, the elemental ratios on the surface of the photopolymer layer can be confirmed by using photoelectron spectroscopy, also known as X-ray photoelectron spectroscopy (XPS) or electron spectroscopy for chemical analysis (ESCA). According to the photoelectron spectroscopy described in the test examples below, after qualitatively analyzing the elements found on the surface of the sample to be analyzed using a survey scan, the elemental ratio can be measured by performing a narrow scan for each element found. The elemental ratios of the photopolymer layer as used herein may be understood as the elemental ratios of the photopolymer layer before recording or after recording. The elemental ratios of the photopolymer layer before recording and after recording may be identical within the experimental error range, but may differ in some embodiments. In other words, even if the elemental ratios of the photopolymer layer before and after recording differ beyond the error range, as long as the elemental ratios before or after recording are within the above-mentioned range, the desired effect of the hologram recording medium of one embodiment can be achieved. The elemental ratio of carbon on the surface of the photopolymer layer contained in the holographic recording medium of the above embodiment is 50 atomic% or more, 51 atomic% or more, 52 atomic% or more, 53 atomic% or more, or 54 atomic% or more, and may be 70 atomic% or less, 69 atomic% or less, or 68 atomic% or less.

[0017] The elemental ratio of nitrogen on the surface of the photopolymer layer is 0.01 atomic% or more, 0.05 atomic% or more, 0.10 atomic% or more, or 0.20 atomic% or more, and may be 2 atomic% or less, 1.8 atomic% or less, 1.6 atomic% or less, 1.4 atomic% or less, or 1.2 atomic% or less.

[0018] 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 30 atomic% or less, 29 atomic% or less, 28 atomic% or less, 27 atomic% or less, or 26 atomic% or less.

[0019] The elemental ratio of fluorine on the surface of the photopolymer layer is 3 atomic% or more, or 4 atomic% or more, and may be 12 atomic% or less, 11 atomic% or less, or 10 atomic% or less.

[0020] The elemental ratio of silicon on the surface of the photopolymer layer is 3 atomic% or more, 4 atomic% or more, or 4.5 atomic% or more, and may be 15 atomic% or less.

[0021] The elemental ratios of carbon, nitrogen, oxygen, fluorine, and silicon are expressed as percentages (atomic %) of the total amount of carbon, nitrogen, oxygen, fluorine, and silicon atoms confirmed by photoelectron spectroscopy on the surface of the photopolymer layer.

[0022] The photopolymer layer, by exhibiting the above-described elemental composition ratio, can exhibit excellent optical recording properties, excellent durability against heat and moisture, suitable adhesion to OCA (optically clear adhesive), and transparent optical properties. In particular, if the elemental ratio of fluorine is below the above range, the optical recording properties will decrease, the material will become susceptible to heat and moisture, and the haze will increase. If the elemental ratio of fluorine exceeds the above range, the optical recording properties will decrease, and the adhesion to OCA may decrease. Also, if the elemental ratio of silicon is below the above range, the material will become susceptible to heat and the haze will increase. If the elemental ratio of silicon exceeds the above range, the optical recording properties may decrease significantly.

[0023] The following describes in detail a holographic recording medium according to one embodiment of the present invention, a method for manufacturing the same, and an optical element including the holographic recording medium.

[0024] The holographic recording medium of the above embodiment includes a polymer matrix or precursor formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)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 aforementioned photopolymer layer may be a photopolymer layer in a pre-recording state capable of recording optical information, or a photopolymer layer in a state where optical information has been recorded.

[0026] A photopolymer layer with recorded optical information can be manufactured by irradiating a pre-recorded photopolymer layer with object light and reference light. When a pre-recorded photopolymer layer is irradiated with object light and reference light, the photoinitiator system is inactive in the canceling interference region due to the interference lengths of the object light and reference light, so photopolymerization of photoreactive monomers does not occur. In the reinforcing interference region, photopolymerization of photoreactive monomers occurs due to the activated photoinitiator system. In the reinforcing interference region, the photoreactive monomers are continuously consumed, creating a concentration difference between the canceling and reinforcing interference regions. As a result, the photoreactive monomers in the canceling interference region diffuse into the reinforcing interference region. At this time, the fluorine-based plasticizer moves in the opposite direction to the photoreactive monomers. Since the photoreactive monomers and the photopolymers formed therefrom have a higher refractive index than the polymer matrix and fluorine-based compounds, a spatial change in refractive index occurs in the photopolymer layer, and a lattice is formed by this spatial refractive index modulation in the photopolymer layer. Such lattice surfaces act as reflective surfaces that reflect incident light due to differences in refractive index. After hologram recording, when light of a specific wavelength is incident in the direction of the reference light, the Bragg condition is satisfied, and the light diffracts in the direction of the original object light, allowing the hologram optical information to be reconstructed.

[0027] Therefore, if the photopolymer layer is in its pre-recording state, the photopolymer layer may contain photoreactive monomers, photoinitiators, and fluorine compounds randomly dispersed within the polymer matrix or its precursor.

[0028] In contrast, if optical information is recorded in the photopolymer layer, the photopolymer layer may contain a photopolymer and a fluorine-based compound distributed to form a lattice with the polymer matrix.

[0029] The photopolymer layer is formed from a photopolymer composition comprising a polymer matrix or its precursor formed by crosslinking a siloxane polymer containing silane functional groups and a (meth)acrylic polyol; a fluorine compound; a photoreactive monomer; and a photoinitiator system.

[0030] The polymer matrix is ​​formed by crosslinking a siloxane polymer containing a silane functional group (Si-H) with a (meth)acrylic polyol. Specifically, the polymer matrix is ​​formed by crosslinking a (meth)acrylic polyol with a siloxane polymer containing a silane functional group. More specifically, the hydroxyl group of the (meth)acrylic polyol can form a crosslink with the silane functional group of the siloxane polymer through a hydrosilylation reaction. This hydrosilylation reaction can be carried out rapidly even at relatively low temperatures (for example, around 60°C) under a Pt-based catalyst. Therefore, the photopolymer composition of the above embodiment can improve the manufacturing efficiency and productivity of holographic recording media by employing a polymer matrix that can be rapidly crosslinked even at relatively low temperatures as a support.

[0031] The polymer matrix, with its flexible main chain of siloxane polymer, can enhance the mobility of components contained in the photopolymer layer (e.g., photoreactive monomers or plasticizers). Furthermore, the siloxane bonds, which have excellent heat resistance and moisture resistance, facilitate the assurance of reliability of the photopolymer layer on which optical information is recorded and the holographic recording medium containing it.

[0032] The polymer matrix may have a relatively low refractive index, thereby playing 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. 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, "refractive index" may be a value measured with an Abbe refractometer at 25°C.

[0033] The photopolymer layer includes a polymer matrix formed by crosslinking a siloxane-based polymer containing the silane functional group described above and a (meth)acrylic polyol, but may also include a polymer matrix precursor that is not partially crosslinked. In this case, the polymer matrix precursor can mean a siloxane-based polymer, a (meth)acrylic polyol, and a Pt-based catalyst.

[0034] The siloxane polymer may, for example, include 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).

[0035] [ka]

[0036] In the aforementioned chemical formula 1, Multiple R 1 and R 2 These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. n is an integer between 1 and 10,000.

[0037] [ka]

[0038] In the above chemical formula 2 (Chemical Formula 2), Multiple R 11 ~R 13 These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. At least one repeating unit of the repeating unit represented by chemical formula 1 and R of either of the terminal groups of the terminal groups represented by chemical formula 2 1 , R 2 and R 11 ~R 13 At least one of them is hydrogen.

[0039] In the aforementioned chemical formula 2, -(O)- means that when the Si of the terminal group represented by the chemical formula 2 is bonded to the repeating unit represented by the chemical formula 1, it is bonded via oxygen (O) or directly without oxygen (O).

[0040] In this specification, “alkyl group” may be a linear, branched, or cyclic alkyl group. In non-limiting examples, “alkyl group” in this specification may include 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-dimethylpropyl, 1-ethylpropyl, 1-methylbutyl, cyclopentyl, etc.), and hexyl (e.g., n-hexyl, 1-methylpentyl, 2-methyl It may also be pentyl, 4-methylpentyl, 3,3-dimethylbutyl, 1-ethylbutyl, 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.), etc.

[0041] As an example, R in chemical formulas 1 and 21 , R 2 and R 11 ~R 13 is methyl or hydrogen, and a plurality of R 1 , R 2 and R 11 ~R 13 At least two or more of may be hydrogen. More specifically, as the siloxane polymer, R in the chemical formula 1 1 and R 2 are methyl and hydrogen, respectively, and R in the chemical formula 2 11 ~R 13 are each independently methyl or hydrogen (for example, polymethylhydrogensiloxane having a trimethylsilyl group or a dimethylhydrosilyl group as a terminal group); a part of R in the chemical formula 1 1 and R 2 are methyl and hydrogen, respectively, 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, polydimethylsiloxane-co-methylhydrogensiloxane 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 having one or all of the terminal groups as dimethylhydrosilyl groups) may also be used.

[0042] The siloxane compound may, for example, have a number-average molecular weight (Mn) in the range of 200 to 4,000. Specifically, the lower limit of the number-average molecular weight of the siloxane polymer may be, for example, 200 or more, 250 or more, 300 or more, or 350 or more, and the upper limit may be, for example, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less, 1,500 or less, or 1,000 or less. When the number-average molecular weight of the siloxane polymer satisfies the above range, it is possible to prevent problems such as the siloxane polymer volatilizing and the matrix crosslinking degree decreasing during the crosslinking process with the (meth)acrylic polyol carried out at room temperature or above, or the siloxane polymer having poor compatibility with other components of the photopolymer layer and phase separation occurring with such components, thereby enabling the holographic recording medium to exhibit excellent optical recording characteristics and heat and humidity resistance.

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

[0044] The silane functional group (Si-H) equivalent of the siloxane polymer may be, for example, in the range of 30 g / equivalent to 200 g / equivalent. More specifically, the silane functional group (Si-H) equivalent of the siloxane 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, "equivalent weight of a functional group" is a simplified term for the gram equivalent number (sometimes called equivalent weight) expressed in units of g / equivalent, and means the value obtained by dividing the molecular weight (such as weight-average molecular weight or number-average molecular weight) of the molecule or polymer containing the functional group by the number of the functional group. Therefore, the smaller the equivalent value, the higher the density of the functional group, and the larger the equivalent value, the lower the density of the functional group.

[0046] When the silane functional group equivalent of the siloxane polymer satisfies the above range, the polymer matrix has an appropriate crosslinking density and fully performs its role as a support, improving the fluidity of the components contained in the photopolymer layer, eliminating the problem of the diffraction grating interface collapsing after recording, maintaining the initial refractive index modulation value at an excellent level even over time, and minimizing the decrease in recording characteristics for optical information.

[0047] The (meth)acrylic polyol can mean a polymer in which one or more, specifically two or more hydroxyl groups are bonded to the main chain or side chain of a (meth)acrylate polymer. In this specification, "(meth)acrylic(system)" refers to acrylic(system) and / or methacrylic(system) unless otherwise specified, and is a term that encompasses all acrylic(system), methacrylic(system), or mixtures of acrylic(system) and methacrylic(system).

[0048] The (meth)acrylic polyol may be a homopolymer of (meth)acrylate monomers having hydroxyl groups, a copolymer of (meth)acrylate monomers having two or more hydroxyl groups, or a copolymer of (meth)acrylate monomers having hydroxyl groups and (meth)acrylate monomers not having hydroxyl groups. In this specification, unless otherwise specified, "copolymer" is a term that encompasses random copolymers, block copolymers, and graft copolymers.

[0049] Examples of (meth)acrylate monomers having a hydroxyl group include hydroxyalkyl (meth)acrylate or hydroxyaryl (meth)acrylate, where 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 (meth)acrylate monomers not having a hydroxyl group include alkyl (meth)acrylate monomer or aryl (meth)acrylate monomer, where the alkyl is an alkyl having 1 to 30 carbon atoms, and the aryl may be an aryl having 6 to 30 carbon atoms.

[0050] The (meth)acrylic polyol may, for example, have a weight-average molecular weight (Mw) in the range of 150,000 to 1,000,000. The weight-average molecular weight refers to the weight-average molecular weight in polystyrene terms measured by the GPC method as described above. For example, the lower limit of the weight-average molecular weight may be 150,000 or more, 200,000 or more, or 250,000 or more, and the upper limit may be, for example, 900,000 or less, 850,000 or less, 800,000 or less, 750,000 or less, 700,000 or less, 650,000 or less, 600,000 or less, 550,000 or less, 500,000 or less, or 450,000 or less. When the weight-average molecular weight of the (meth)acrylic polyol satisfies the aforementioned range, the polymer matrix fully performs its function as a support, resulting in minimal decrease in recording characteristics for optical information even after extended use. This imparts sufficient flexibility to the polymer matrix, improving the mobility of components contained in the photopolymer layer (e.g., photoreactive monomers or plasticizers) and minimizing the decrease in recording characteristics for optical information.

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

[0052] Specifically, the hydroxyl group (-OH) equivalent of the (meth)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 (meth)acrylic polyol may be 600 g / equivalent or more, 700 g / equivalent or more, 800 g / equivalent or more, 900 g / equivalent or more, 1000 g / equivalent or more, 1100 g / equivalent or more, 1200 g / equivalent or more, 1300 g / equivalent or more, 1400 g / equivalent or more, 1500 g / equivalent or more, 1600 g / equivalent or more, 1700 g / equivalent or more, or 1750 g / equivalent or more. Furthermore, the upper limit of the hydroxyl group (-OH) equivalent of the (meth)acrylic polyol may be 2900 g / equivalent or less, 2800 g / equivalent or less, 2700 g / equivalent or less, 2600 g / equivalent or less, 2500 g / equivalent or less, 2400 g / equivalent or less, 2300 g / equivalent or less, 2200 g / equivalent or less, 2100 g / equivalent or less, 2000 g / equivalent or less, or 1900 g / equivalent or less.

[0053] When the hydroxyl group (-OH) equivalent of the (meth)acrylic polyol satisfies the above range, the polymer matrix has an appropriate crosslinking density and fully performs its role as a support, improving the fluidity of the components contained in the photopolymer layer. This prevents the problem of the diffraction grating interface collapsing after recording, and maintains the initial refractive index modulation value at an excellent level even after time has passed, minimizing the decrease in recording characteristics for optical information.

[0054] The (meth)acrylic polyol may have a glass transition temperature (Tg) in the range of -60°C to -10°C, for example. Specifically, the lower limit of the glass transition temperature may be, for example, -55°C or higher, -50°C or higher, -45°C or higher, -40°C or higher, -35°C or higher, -30°C or higher, or -25°C or higher, and the upper limit may be, for example, -15°C or lower, -20°C or lower, -25°C or lower, -30°C or lower, or -35°C or lower. When the glass transition temperature range is satisfied, the glass transition temperature can be lowered without significantly reducing the modulus of the polymer matrix, thereby 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 (meth)acrylic polyol may be, for example, 1.40 or more and less than 1.50. Specifically, the lower limit of the refractive index of the (meth)acrylic polyol may be, for example, 1.41 or more, 1.42 or more, 1.43 or more, 1.44 or more, 1.45 or more, or 1.46 or more, and the upper limit may be, for example, 1.49 or less, 1.48 or less, 1.47 or less, 1.46 or less, or 1.45 or less. When the (meth)acrylic polyol has a refractive index within the range described above, it can contribute to increasing refractive index modulation. The refractive index of the (meth)acrylic polyol is a theoretical refractive index and can be calculated using the refractive index of the monomers used in the production of the (meth)acrylic polyol (value measured using an Abbe refractometer at 25°C) and the fraction (molar ratio) of each monomer.

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

[0057] The molar ratio of silane functional groups of a siloxane polymer to hydroxyl groups of the (meth)acrylic polyol (hereinafter simply referred to as the SiH / OH molar ratio) can be calculated from the weight of each polymer and the number of moles of the functional group confirmed from the equivalent amount of the functional group in each polymer.

[0058] Specifically, the silane functional group equivalent of a siloxane polymer is the value obtained by dividing the molecular weight (e.g., number-average molecular weight) of the siloxane polymer by the number of silane functional groups per molecule, and the hydroxyl group equivalent of the (meth)acrylic polyol is the value obtained by dividing the molecular weight (e.g., weight-average molecular weight) of the (meth)acrylic polyol by the number of hydroxyl functional groups per molecule. Therefore, by dividing the weight of a siloxane polymer by the silane functional group equivalent of the siloxane polymer, the number of moles of silane functional groups can be determined, and by dividing the weight of a (meth)acrylic polyol by the hydroxyl group equivalent of the (meth)acrylic polyol, the number of moles of hydroxyl groups can be determined. More specifically, taking Example 3, which will be described later, as an example, if we divide the weight of the siloxane polymer used in Example 3 (2.6 g) by the silane functional group equivalent of the siloxane polymer used in Example 3 (103 g / equivanlent), we can calculate the number of moles of silane functional groups (0.0252 mol). If we divide the weight of the (meth)acrylic polyol used in Example 3 (22.4 g) by the hydroxyl group equivalent of the (meth)acrylic polyol used in Example 3 (1802 g / equivanlent), we can calculate the number of moles of hydroxyl groups (0.0124 mol). Dividing the number of moles of silane functional groups (0.0252 mol) calculated in this way by the number of moles of hydroxyl groups (0.0124 mol) confirms that the molar ratio of SiH / OH is calculated to be 2.

[0059] The lower limit of the SiH / OH molar ratio may be, for example, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, or 2.0 or more, and the upper limit may be, for example, 3.9 or less, 3.8 or less, 3.7 or less, 3.6 or less, or 3.5 or less. When the SiH / OH molar ratio range is satisfied, the polymer matrix is ​​crosslinked with an appropriate crosslinking density, improving the fluidity of recording components (e.g., photoreactive monomers and plasticizers) and ensuring excellent optical recording properties. Even when placed in a high-temperature / high-humidity environment after recording, migration or deformation of components within the photopolymer layer and penetration of moisture into the photopolymer layer are suppressed, resulting in excellent heat and humidity resistance and transparent optical properties.

[0060] The Pt-based catalyst may, for example, be a Karstedt catalyst. The Pt-based catalyst may be present in an amount of 0.01 to 2 parts by weight per 100 parts by weight of the (meth)acrylic polyol. Specifically, the Pt-based catalyst may be present in an amount of 0.01 parts by weight or more, 0.02 parts by weight or more, 0.03 parts by weight or more, 0.04 parts by weight or more, 0.05 parts by weight or more, or 0.06 parts by weight or more, and 1.5 parts by weight or less, 1.0 part 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 per 100 parts by weight of the (meth)acrylic polyol. When the Pt-based catalyst is used in the above-mentioned amounts, the polymer matrix can be crosslinked with an appropriate crosslinking density to exhibit the desired optical recording characteristics.

[0061] For example, when the molar ratio of silane functional groups of the siloxane polymer, which acts as a crosslinking agent, is high, around 1.5 to 4, compared to the hydroxyl groups of the (meth)acrylic polyol, which is the main component forming the polymer matrix, and the content of the Pt catalyst is adjusted to 0.01 to 0.30 parts by weight per 100 parts by weight of the (meth)acrylic polyol, the polymer matrix has an appropriate crosslinking density, and as a result, a photopolymer layer exhibiting transparent optical properties can be provided.

[0062] The polymer matrix precursor may optionally contain, in addition to the Pt-based catalyst, other non-metallic catalysts such as rhodium-based, iridium-based, rhenium-based, molybdenum-based, iron-based, nickel-based, alkali metal or alkaline earth metal-based, Lewis acid-based, or carbene-based catalysts.

[0063] On the other hand, in the holographic recording medium of the above embodiment, optical information can be recorded by irradiating the photopolymer layer with object light and reference light. Depending on the interference length of the object light and reference light, photopolymerization of photoreactive monomers does not occur in the canceling interference region, while photopolymerization of photoreactive monomers occurs in the reinforcement interference region. As the photoreactive monomers are continuously consumed in the reinforcement interference region, a concentration difference between the photoreactive monomers in the canceling interference region and the reinforcement interference region is created, and as a result, the photoreactive monomers in the canceling interference region diffuse into the reinforcement interference region. A diffraction grating is generated by the refractive index modulation that occurs in this way.

[0064] Therefore, in order to achieve the refractive index modulation described above, the photoreactive monomer may include compounds having a higher refractive index than the polymer matrix. However, it is not limited to all photoreactive monomers having a higher refractive index than the polymer matrix; at least some photoreactive monomers may have a higher refractive index than the polymer matrix in order to achieve a high refractive index modulation value. As an example, the photoreactive monomer may include monomers with refractive indices of 1.50 or higher, 1.51 or higher, 1.52 or higher, 1.53 or higher, 1.54 or higher, 1.55 or higher, 1.56 or higher, 1.57 or higher, 1.58 or higher, 1.59 or higher, or 1.60 or higher and 1.70 or lower.

[0065] The photoreactive monomer may include one or more monomers selected from the group consisting of monofunctional monomers having one photoreactive functional group and polyfunctional monomers having two or more photoreactive functional groups. In this case, the photoreactive functional group may be, for example, a (meth)acryloyl group, a vinyl group, or a thiol group. More specifically, the photoreactive functional group may be a (meth)acryloyl group.

[0066] The monofunctional monomer may include, for example, one or more selected from the group consisting of benzyl (meth)acrylate (Miwon M1182 refractive index 1.5140), benzyl 2-phenyl acrylate, phenoxybenzyl (meth)acrylate (Miwon M1122 refractive index 1.565), phenol (ethylene oxide) (meth)acrylate (phenol(EO)(meth)acrylate; Miwon M140 refractive index 1.516), phenol (ethylene oxide) 2 (meth)acrylate (phenol(EO)2(meth)acrylate; Miwon M142 refractive index 1.510), O-phenylphenol (ethylene oxide) (meth)acrylate (O-phenylphenol(EO)(meth)acrylate; Miwon M1142 refractive index 1.577), phenylthioethyl (meth)acrylate (Miwon M1162 refractive index 1.560), and biphenylmethyl (meth)acrylate.

[0067] The aforementioned polyfunctional monomer is, for example, bisphenol A (ethylene oxide) 2~10 Di(meth)acrylate (bisphenol A(EO) 2~10(meth)acrylate; Miwon's M240 refractive index 1.537, M241 refractive index 1.529, M244 refractive index 1.545, M245 refractive index 1.537, M249 refractive index 1.542, M2100 refractive index 1.516, M2101 refractive index 1.512), Bisphenol A epoxy di(meth)acrylate (Miwon's PE210 refractive index 1.557, PE2120A refractive index 1.533, PE2120B refractive index 1.534, PE2020C refractive index 1.539, PE2120S refractive index 1.556), Bisful Orange (meth)acrylate (Miwon's HR6022 refractive index 1.600, HR6040 refractive index 1.600, HR60 It may contain one or more substances selected from the group consisting of 42 (refractive index 1.600), modified bisphenol full orange (meth)acrylate (Miwon's HR6060 refractive index 1.584, HR6100 refractive index 1.562, HR6200 refractive index 1.530), tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate (Miwon's M370 refractive index 1.508), phenol novolac epoxy (meth)acrylate (Miwon's SC6300 refractive index 1.525), and cresol novolac epoxy (meth)acrylate (Miwon's SC6400 refractive index 1.522, SC6400C refractive index 1.522).

[0068] The photopolymer layer may contain 50 to 300 parts by weight of a photoreactive monomer per 100 parts by weight of the polymer matrix. For example, the lower limit of the photoreactive monomer content may be 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, and the upper limit may be 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. When the above range is met, a photopolymer layer can be provided that exhibits excellent optical recording properties, heat resistance and heat / humidity resistance, high transparency, and suitable adhesion to OCA.

[0069] In this specification, the polymer matrix content refers to the combined content (by weight) of the (meth)acrylic polyol and siloxane polymer that form the matrix. In other words, the polymer matrix content refers to the total content including the polymer matrix formed by the cross-linking of the (meth)acrylic polyol and siloxane polymer, and the polymer matrix precursor that is not partially cross-linked.

[0070] The photopolymer layer includes a photoinitiator system. The photoinitiator system can mean a photoinitiator that enables polymerization to begin upon exposure to light, or a combination of a photosensitizer and a coinitiator.

[0071] The aforementioned photopolymer layer may include a photoinitiator system consisting of a photodepressant and a co-initiator.

[0072] For example, a photosensitive dye can be used as the aforementioned photoreducing agent. Specifically, the photosensitive dyes include, for example, silicon rhodamine compounds, sulfonium derivatives of ceramidenin, 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, and brilliant green. One or more substances selected from the group consisting of Green, Astrazon Orange G, Darrow Red, Pyronin Y, Basic Red 29, Pyrylium I (pyrylium iodide), Safranin O, Cyanine, Methylene Blue, Azure A, and BODIPY may be used.

[0073] As an example, a silicon rhodamine compound represented by the following chemical formula 3 (Chemical Formula 3) can be used as the photosensitive dye.

[0074] [ka]

[0075] In the aforementioned chemical formula 3, R 21 ~R 29 Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, or a substituted or unsubstituted C6-C30 aryloxy group. d and e are each independent integers between 0 and 3. f is an integer between 0 and 5. An - It is an anion.

[0076] In this specification, “substituted or unsubstituted” means that hydrogen or carbon is substituted with another element, where hydrogen may be substituted with a halogen, a hydroxyl group, a C1-C10 alkyl group, or a C1-C10 alkoxy group, and carbon (-CH2-) may be substituted with -O- or -CO-.

[0077] In the above chemical formula 3, R 21 ~R 28 Each of these may independently be a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. Specifically, in the above chemical formula 3, R 21 ~R 28 Each of these may independently be an alkyl group having 1 to 6 carbon atoms. More specifically, in the above chemical formula 3, R 21 ~R 28 It may be a methyl group.

[0078] In the aforementioned chemical formula 3, d and e may each be an integer between 0 and 2, an integer between 0 and 1, or 0, independently of each other.

[0079] In the above chemical formula 3, f may be an integer between 0 and 5, an integer between 0 and 4, an integer between 0 and 3, an integer between 0 and 2, or an integer between 1 and 2.

[0080] In the above chemical formula 3, R 29R may be a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. Specifically, in the above chemical formula 3, 29 R may be an alkoxy group having 1 to 6 carbon atoms. More specifically, in the above chemical formula 3, 29 This may be a methoxy group.

[0081] In the above chemical formula 3, the anion (An - ) may be a halide anion, a cyano anion, a sulfonate anion, a carbon 1-30 alkoxy anion, a substituted or unsubstituted carbon 1-30 alkyl sulfonate anion, a substituted or unsubstituted carbon 6-30 aromatic sulfonate anion, or a substituted or unsubstituted carbon 6-30 aromatic borate anion.

[0082] Specifically, in the above chemical formula 3, the anion (An - ) may be a substituted or unsubstituted C1-C30 alkyl sulfonate anion, a substituted or unsubstituted C6-C30 aromatic sulfonate anion, or a substituted or unsubstituted C6-C30 aromatic borate anion.

[0083] More specifically, in the above chemical formula 3, the anion (An - ) may be an alkyl sulfonate anion having 2 to 15 carbon atoms with one or more hydrogen atoms substituted or unsubstituted with fluorine, an alkyl sulfonate anion having 6 to 30 carbon atoms with one or more carbon atoms substituted or unsubstituted with -O- or -CO- (Chemical Formula 4), a phenyl sulfonate anion substituted or unsubstituted with methyl, or a substituted or unsubstituted tetraarylborate anion. For example, in the above chemical formula 3, the anion (An - ) may be a dodecyl sulfonate anion, a perfluorobutyl sulfonate anion, a phenyl sulfonate anion, a methylphenyl sulfonate anion, or a tetraphenyl borate anion.

[0084] [ka]

[0085] The photopolymer layer may contain the photosensitive dye in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the polymer matrix. Specifically, the lower limit of the photosensitive dye content may be, for example, 0.02 parts by weight or more, 0.03 parts by weight or more, or 0.05 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous to exhibit an appropriate polymerization reaction rate and ensure the desired optical recording characteristics.

[0086] The co-initiator may be an electron donor, an electron acceptor, or a mixture thereof.

[0087] As an example, the photopolymer composition of the above embodiment may contain an electron donor as a co-initiator. The electron donor may, for example, include a borate anion represented by the following chemical formula 4 (Chemical Formula 5).

[0088] [ka]

[0089] In the aforementioned chemical formula 4, X 1 ~X 4 Each of these is independently a substituted or unsubstituted C1-C20 alkyl group, a C2-C20 alkenyl group, a C6-C30 aryl group, a C7-C30 arylalkyl (arylalkyl) group, a C7-C30 alkylaryl (alkylaryl) group, or an allyl group, and X 1 ~X 4 At least one of them is not an aryl group.

[0090] When the C1-C20 alkyl group, C2-C20 alkenyl group, C6-C30 aryl group, C7-C30 arylalkyl (arylalkyl) group, C7-C30 alkylaryl (alkylaryl) group, or allyl group is substituted, it may be substituted with one or more selected from the group consisting of halogens, vinyl groups, C1-C5 haloalkyl groups, and C1-C5 alkoxy groups.

[0091] Specifically, X 1 ~X 3 Each of these is independently a phenyl, methylphenyl, naphthyl, or methylnaphthyl substituted or unsubstituted with one or more substituents selected from the group consisting of halogens, vinyl groups, trifluoromethyl groups, and methoxy groups, and X 4 This may be a linear alkyl group having 1 to 12 carbon atoms.

[0092] More specifically, the borate anion represented by chemical formula 4 may be one or more selected from the group consisting of borate anions represented by the following chemical formulas 4-1 (Chemical Formula 6) and 4-2 (Chemical Formula 7).

[0093] [ka]

[0094] In the aforementioned chemical formula 4-1, R 102 These are, independently, methyl or halogen, R 103 Each is independently of hydrogen, methyl, or halogen, and adjacent to R 102 If it is methyl, it is a halogen, X 4’ These are linear alkyl groups having 1 to 12 carbon atoms.

[0095] [ka]

[0096] In the aforementioned chemical formula 4-2, R 106 These are, independently, hydrogen, methyl, or halogen. X 4” These are linear alkyl groups having 1 to 12 carbon atoms.

[0097] In the above chemical formula 4-2, R 106 Each of these elements is independently hydrogen, methyl, or halogen, and at least one of them may be a halogen.

[0098] When using borate anions represented by chemical formulas 4-1 and 4-2 below as the electron donors, excellent heat resistance can be ensured even before recording.

[0099] In the chemical formulas 4-1 and 4-2, the halogen may be fluorine or chlorine. In particular, chlorine can ensure even better heat resistance.

[0100] The cation bonded to the borate anion is one or more cations selected from the group consisting of alkali metal cations, quaternary ammonium cations, and nitrogen-containing heterocyclic cations, and does not absorb light.

[0101] The alkali metal cation may be one or more selected from the group consisting of, for example, lithium, sodium, potassium, rubidium, and cesium.

[0102] 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 with nitrogen are linked together, or a mixture thereof.

[0103] Specifically, the quaternary ammonium cation may be a cation represented by the following chemical formula 4-3 (Chemical Formula 8).

[0104] [ka]

[0105] In the above chemical formula 4-3, Y 1 ~Y 4 The two substituents may or may not be linked to each other to form an aliphatic ring having 4 to 10 carbon atoms. Y that does not form an aliphatic ring 1 ~Y 4 Each of these is independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms linked via an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3), Y 1 ~Y 4 If all substituents are methyl groups, or if two or more substituents are alkyl groups with 16 or more carbon atoms, then those are excluded.

[0106] In the above chemical formula 4-3, Y 1 ~Y 4 If all of the substituents are methyl groups, or if two or more substituents are alkyl groups having 16 or more carbon atoms, the electron donor may not dissolve well in the photopolymer composition and may not exhibit the desired optical recording properties.

[0107] Specifically, Y 1 ~Y 4 The two substituents can be linked together to form piperidine or pyrrolidine.

[0108] The aforementioned Y 1 ~Y 4 Among these substituents that do not form an aliphatic ring, each may 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 Y 1 ~Y 4The substituents that do not form an aliphatic ring may independently be a methyl group, a butyl group, a hexadecyl group, a hentriacontyl group, a phenyl group, or a benzyl group.

[0109] The nitrogen-containing heterocyclic cation may also be a heteroaromatic cation containing one or more nitrogen atoms. Examples of such heteroaromatic cations include pyrrole, pyrazole, imidazole, or pyridine cations, and these hydrogen atoms may be substituted or unsubstituted.

[0110] As an example, the nitrogen-containing heterocyclic cation may be a cation represented by the following chemical formula 4-4 (Chemical Formula 9).

[0111] [ka]

[0112] In the above chemical formula 4-4, R 107 , R 109 and R 110 These are, independently, hydrogen, a C1-C40 alkyl group, a C6-C30 aryl group, a C6-C40 arylalkyl group, or a C2-C40 alkyl group linked via an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3), R 108 and R 111 These are, independently, C1-C40 alkyl groups, C6-C30 aryl groups, C6-C40 arylalkyl groups, or C2-C40 alkyl groups linked via ester bonds (e.g., -CH2CH2-O-CO-CH2CH2CH3).

[0113] Specifically, R 107 , R 109 and R 110 Each of these may 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.

[0114] 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.

[0115] The cation combined with the borate anion may include, for example, one or more selected from the group consisting of tetrabutylammonium cation, hexadecyl dimethyl benzyl ammonium cation, hentriacontyl dimethyl benzyl ammonium cation, hexadecyl benzyl piperidinium cation, hexadecyl benzyl pyrrolidinium cation, 1-hexadecyl-3-benzyl imidazolium cation and 1,3-dihexadecyl-2-phenyl imidazolium cation.

[0116] 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 substituted with other cations known in the related technical field. As a non-limiting example, a part of the above-mentioned cations may be substituted with 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium or the like.

[0117] As an example, the photopolymer layer may contain an electron acceptor as a co-initiator. The electron acceptor may include, for example, onium salts such as sulfonium salts and iodonium salts; triazine compounds such as tris(trihalomethyl)triazine and substituted bis(trihalomethyl)triazine; or mixtures thereof.

[0118] As an example, the electron acceptor may include (4-(octyloxy)phenyl)(phenyl)iodonium salt as an iodonium salt, or 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine as a triazine compound. 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.

[0119] The photopolymer layer may contain the co-initiator in an amount ranging from 0.05 to 10 parts by weight per 100 parts by weight of the polymer matrix. Specifically, the lower limit of the co-initiator content may be, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above range is satisfied, it is advantageous to exhibit an appropriate polymerization reaction rate and ensure the desired optical recording characteristics.

[0120] The photoinitiator system may include additional photoinitiators to remove the color of the photosensitive dye and to react all unreacted photoreactive monomers after light irradiation for recording. Examples of the photoinitiators include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, thioxanthone derivatives, amine derivatives, diazonium salts, sulfonium salts, iodonium salts, sulfonic acid esters, imidosulfonates, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η6-benzene)(η5-cyclopentadienyl)iron(II), benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosylphthalimide, or mixtures thereof.More specifically, the photoinitiators include 1,3-di(t-butyldioxycarbonyl)benzophenone, 3,3',4,4''-tetrakis(t-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, and 2-mercapto benzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one (product name: Irgacure 651 / manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure 184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure 369 / manufacturer: BASF), 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 Examples include, but are not limited to, UVI-6974, Cyracure UVI-6990 (manufactured by Dow Chemical Co., USA), Irgacure 264, Irgacure 250 (manufactured by BASF), CIT-1682 (manufactured by Nippon Soda), or mixtures thereof.

[0121] The photopolymer layer may contain the photoinitiator in an amount ranging from 0.05 to 10 parts by weight per 100 parts by weight of the polymer matrix. Specifically, the lower limit of the photoinitiator content may be, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more, and the upper limit may be, for example, 5 parts by weight or less. When the above range is met, 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.

[0122] The photopolymer layer contains a fluorine-based compound as a plasticizer. The plasticizer can more easily achieve refractive index modulation during the manufacturing of the holographic recording medium. More specifically, the plasticizer lowers the glass transition temperature of the polymer matrix, improving the fluidity of the photoreactive monomers. It has low refractive index and non-reactive properties, is uniformly distributed within the polymer matrix, and when the photoreactive monomers that have not been photopolymerized move, it moves in the opposite direction, contributing to refractive index modulation. The plasticizer can also contribute to improving the moldability of the photopolymer composition.

[0123] The fluorine-based compound may have a low refractive index of 1.45 or less in order to perform the function of a plasticizer as described above. Specifically, the upper limit of the refractive index may be, for example, 1.44 or less, 1.43 or less, 1.42 or less, 1.41 or less, 1.40 or less, 1.40 or less, 1.39 or less, 1.38 or less, or 1.37 or less, and the lower limit of the refractive index may be, for example, 1.30 or more, 1.31 or more, 1.32 or more, 1.33 or more, 1.34 or more, or 1.35 or more. By using a fluorine-based compound having a lower refractive index than the photoreactive monomer described above, the refractive index of the polymer matrix can be made even lower, and the refractive index modulation with the photoreactive monomer can be made larger.

[0124] 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, for example, a compound containing a repeating unit represented by the following Chemical Formula 5 (Chemical Formula 10).

[0125]

Chemical Formula

[0126] In the Chemical Formula 5, 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.

[0127] More specifically, the fluorine-based compound may be a compound containing 1 to 3 units represented by the following Chemical Formula 5-1 (Chemical Formula 11).

[0128]

Chemical Formula

[0129] In the Chemical Formula 5-1, R 41 ~R 44 and R 53 ~R 56 are each independently hydrogen or fluorine, and R 45 ~R 52 is fluorine.

[0130] As an example, in the Chemical Formula 5-1, R 41 , R 42 , R 55 and R 56 are hydrogen, and R 43 ~R 54 is fluorine.

[0131] Fluorine compounds containing the (repeating) units represented by chemical formulas 5 and 5-1 are not particularly limited, but may be capped with end capping agents widely used in the relevant art. For example, the ends of fluorine compounds containing the (repeating) units represented by chemical formulas 5 and 5-1 may be alkyl groups or alkyl groups substituted with one or more alkoxy groups. As a non-limiting example, the ends of fluorine compounds containing the (repeating) units represented by chemical formulas 5 and 5-1 may be 2-methoxyethoxymethyl groups using 2-methoxyethoxymethyl chloride as the end capping agent.

[0132] The fluorinated compound may have a weight-average molecular weight of 300 or more. Specifically, the lower limit of the weight-average molecular weight of the fluorinated compound may be, for example, 350 or more, 400 or more, 450 or more, 500 or more, or 550 or more, and the upper limit may be, for example, 1000 or less, 900 or less, 800 or less, 700 or less, or 600 or less. When considering refractive index modulation, compatibility with other components, and the elution of the fluorinated compound, it is preferable to satisfy the above range of weight-average molecular weight. In this case, the weight-average molecular weight refers to the weight-average molecular weight in terms of polystyrene measured by the GPC method as described above.

[0133] The photopolymer layer may contain 20 to 200 parts by weight of the fluorine-based compound per 100 parts by weight of the polymer matrix. Specifically, the lower limit of the fluorine-based compound content 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, and the upper limit may be, for example, 190 parts by weight or less, 180 parts by weight or less, 170 parts by weight or less, 160 parts by weight or less, or 155 parts by weight or less. When the above range is met, there are no problems such as deterioration of compatibility with the components contained in the photopolymer layer causing some of the fluorine-based compound to dissolve onto the surface of the photopolymer layer or deterioration of haze, and it is possible to show a large refractive index modulation value after recording with a fluorine-based compound having a sufficiently low refractive index, which is advantageous in ensuring excellent optical recording characteristics.

[0134] The majority of the components of the photopolymer layer can be said to be a polymer matrix, a photoreactive monomer, and a fluorinated compound. Therefore, the elemental composition ratio of the surface of the photopolymer layer can be controlled by the blending ratio of the polymer matrix, the photoreactive monomer, and the fluorinated compound. In order to satisfy the elemental composition ratio described above, the photopolymer layer may contain 17% to 38% by weight of polymer matrix, 36% to 58% by weight of photoreactive monomer, and 17% to 38% by weight of fluorinated compound, relative to the total weight of the polymer matrix, photoreactive monomer, and fluorinated compound.

[0135] More specifically, the polymer matrix may contain, for example, 17% or more by weight, 18% or more by weight, 19% or more by weight, or 20% or more by weight and 38% or less by weight, 37% or less by weight, or 36% or less by weight. The photoreactive monomer may contain, for example, 36% or more by weight, 37% or more by weight, or 38% or more by weight and 58% or less by weight, 55% or less by weight, or 53% or less by weight. The fluorine-based compound may contain, for example, 17% or more by weight, 18% or more by weight, 19% or more by weight, or 20% or more by weight and 38% or less by weight, 35% or less by weight, 33% or less by weight, or 32% or less by weight. A photopolymer layer satisfying the above-mentioned elemental composition ratio can be provided within such ranges.

[0136] The photopolymer layer may additionally contain additives such as surfactants or defoaming agents.

[0137] The photopolymer layer may include a silicone-based surfactant, a fluorine-based surfactant, or a mixture thereof as the surfactant.

[0138] Examples of the aforementioned silicone-based surfactants include BYK-077, BYK-085, BYK-300, BYK-301, BYK-302, BYK-306, BYK-307, BYK-310, BYK-320, BYK-322, BYK-323, BYK-325, BYK-330, BYK-331, BYK-333, BYK-335, BYK-341v344, BYK-345v346, BYK-348, BYK-354, BYK-355, BYK-356, BYK-358, BYK-361, BYK-370, BYK-371, BYK-375, BYK-380, BYK-390, and BYK-3550 from BYK Chemie. The aforementioned fluorine-based surfactants include DIC (DaiNippon Ink & Chemicals) 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. can be used.

[0139] If the photopolymer layer contains a surfactant, the surfactant may be present in amounts of 0.01 parts by weight or more, 0.02 parts by weight or more, 0.03 parts by weight or more, or 0.05 parts by weight or more and 5 parts by weight or less, or 3 parts by weight or less, per 100 parts by weight of the polymer matrix. When these ranges are met, the photopolymer layer can be given excellent adhesion and release properties, thereby preserving excellent optical recording characteristics.

[0140] The photopolymer layer may contain a silicone-based reactive additive as an antifoaming agent. A commercially available silicone-based reactive additive, such as Tego Rad 2500, can be used. The amount of the antifoaming agent can be appropriately adjusted to a level that does not interfere with the function of the holographic recording medium.

[0141] The aforementioned photopolymer layer may be formed from a photopolymer composition containing a solvent.

[0142] The solvent may be an organic solvent, or, as an example, one or more organic solvents selected from the group consisting of ketones, alcohols, acetates, and ethers, but is not limited thereto. Specific examples of such organic solvents include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or isobutyl ketone; alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, or t-butanol; acetates such as ethyl acetate, i-propyl acetate, or polyethylene glycol monomethyl ether acetate; and one or more ethers selected from the group consisting of tetrahydrofuran or propylene glycol monomethyl ether.

[0143] The organic solvent may be added when the components contained in the photopolymer composition are mixed, or it may be included in the photopolymer composition while the components are dispersed or mixed in the organic solvent.

[0144] The photopolymer composition may contain a solvent such that the solid content concentration is 1% to 90% by weight. Specifically, the photopolymer composition may contain a solvent such that the solid content concentration is 20% or more by weight, 25% or more by weight, or 30% or more by weight, and 50% or less by weight, 45% or less by weight, or 40% or less by weight. Within this range, the photopolymer composition can exhibit appropriate fluidity, form a coating film without defects such as stripes, and form a photopolymer layer that exhibits desired physical properties and surface characteristics without defects occurring during the drying and curing process.

[0145] The holographic recording medium of the above embodiment exhibits excellent refractive index modulation, diffraction efficiency, and driving reliability despite having a thin photopolymer layer.

[0146] The thickness of the photopolymer layer may be, for example, in the range of 5.0 μm to 40.0 μm. Specifically, the lower limit of the thickness of the photopolymer layer may be, for example, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. 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.

[0147] The holographic recording medium of the above embodiment may further include a substrate on at least one surface of the photopolymer layer. The type of substrate is not particularly limited, and any known in the relevant 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.

[0148] The holographic recording medium of the above embodiment can have a high diffraction efficiency. For example, when a notch filter hologram is recorded on the holographic recording medium, it can have a diffraction efficiency of 80% or more. In this case, 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, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, or 96% or more. Thus, the holographic recording medium of the above embodiment can achieve excellent diffraction efficiency even when it contains a thin photopolymer layer. The diffraction efficiency can be measured by the method described in the test examples below.

[0149] The holographic recording medium of the above embodiment can exhibit resistance to heat and / or moisture by including a photopolymer layer that satisfies a specific ratio of elements.

[0150] As an example, the holographic recording medium of the above embodiment may have a diffraction efficiency change value (ΔDE) of 10% or less, calculated by the following formula 2 (equation 1).

[0151]

number

[0152] In Equation 2 above, DE0 is the diffraction efficiency measured on a hologram recording medium on which a Notch filter hologram was recorded after storing the hologram recording medium in a dark room under constant temperature and humidity conditions of 20°C to 25°C and 40RH% to 50RH% before recording, and DE1 is the diffraction efficiency measured on a hologram recording medium on which a Notch filter hologram was recorded after storing the hologram recording medium in a dark room under high temperature conditions of 60°C to 70°C and 40RH% to 50RH% before recording.

[0153] The diffraction efficiency change value is an index that can evaluate the heat resistance (thermal durability) of the hologram recording medium before recording. The higher the heat resistance, the smaller the diffraction efficiency change value (ΔDE) calculated by Equation 2. For a more specific method of measuring the diffraction efficiency change value (ΔDE) calculated by Equation 2, refer to the method described in the test examples below. The diffraction efficiency change value may be 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, or 2% or less.

[0154] The holographic recording medium of the above embodiment can exhibit excellent durability not only against heat but also in high-temperature and high-humidity environments. Specifically, the holographic recording medium of the above embodiment can have a wavelength shift (Δλ) of -10 nm to 10 nm before and after being left at a temperature of 60°C and a relative humidity of 90%.

[0155] The degree of wavelength shift (Δλ) indicating the maximum reflectance is an indicator that can evaluate the heat and humidity resistance (heat and humidity resistance) of the hologram recording medium after recording, and the higher the heat and humidity resistance, the smaller the value of the wavelength shift. For a more specific method of measuring the degree of wavelength shift (Δλ) indicating the maximum reflectance, refer to the method described in the test examples below. The degree of wavelength shift (Δλ) indicating the maximum reflectance before and after being left under high temperature and high humidity conditions may be -10nm to 10nm, -9nm to 9nm, -8nm to 8nm, -7nm to 7nm, -6nm to 6nm, -5nm to 5nm, -4nm to 4nm, -3nm to 3nm, or -2nm to 2nm.

[0156] The holographic recording medium of the above embodiment can exhibit suitable adhesion to an optically transparent adhesive (OCA). Specifically, the adhesion strength of the photopolymer layer to the OCA may be 1000 gf / 25 mm or more. The method for measuring the adhesion strength can be found in the test examples described later. The adhesion strength of the photopolymer layer to the OCA may be 1010 gf / 25 mm or more, 1030 gf / 25 mm or more, or 1100 gf / 25 mm or more. The upper limit of the adhesion strength of the photopolymer layer to the OCA is not particularly limited, but may be 3000 gf / 25 mm or less.

[0157] On the other hand, holographic recording media tend to have opaque properties due to the incompatibility of components with low refractive indices and high refractive indices, as they are used in combination for recording optical properties. However, the holographic recording media of the above embodiment can exhibit highly transparent optical properties by including a photopolymer layer that satisfies a specific ratio of elements.

[0158] As an example, the haze of the hologram recording medium may be 3% or less. The upper limit of the haze may be, for example, 2.5% or less, 2.0% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 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 examples below.

[0159] The holographic recording media of the other embodiments described above are expected to provide a variety of optical elements that can be used even in environments where a lot of heat is generated or humidity is high, by exhibiting excellent optical recording characteristics, resistance to humidity and heat, and high transparency.

[0160] The hologram recording medium of the above embodiment is not limited thereto, but may be one on which a reflective hologram or a transmissive hologram is recorded.

[0161] On the other hand, according to another embodiment of the invention, a method for manufacturing a hologram recording medium is provided, comprising the steps of: applying a photopolymer composition comprising a polymer matrix or precursor thereof formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)acrylic polyol; a fluorine compound; a photoreactive monomer; and a photoinitiator system to form a photopolymer layer; and irradiating a predetermined area of ​​the photopolymer layer with a coherent laser to selectively polymerize the photoreactive monomer contained in the photopolymer layer to record optical information, wherein the photopolymer layer has an elemental ratio of 50 to 70 atoms for carbon, 0.01 to 2 atoms for nitrogen, 15 to 30 atoms for oxygen, 3 to 12 atoms for fluorine, and 3 to 15 atoms for silicon, with respect to the total amount of carbon, nitrogen, oxygen, fluorine, and silicon atoms confirmed on its surface by photoelectron spectroscopy.

[0162] The photopolymer layer having the aforementioned specific elemental composition ratio may be the photopolymer layer included in the holographic recording medium of the above-described embodiment, and since the photopolymer layer has been explained in detail earlier, a detailed explanation will be omitted here.

[0163] In the step of forming the photopolymer layer, a photopolymer composition containing the above-described configuration can first be manufactured. When manufacturing the photopolymer composition, any commonly known mixer, stirrer, or similar device can be used for mixing the components without any limitations. Such a mixing process may be carried out at temperatures in the range of 0°C to 100°C, 10°C to 80°C, or 20°C to 60°C.

[0164] In the step of forming the photopolymer layer, the prepared photopolymer composition can be applied to form a coating film made 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 can be induced between the hydroxyl groups of the unreacted (meth)acrylic polyol and the silane functional groups of the siloxane polymer, thereby achieving the desired crosslinking density while maintaining high transparency.

[0165] The photopolymer layer produced in the step of forming the photopolymer layer may have a fluorine-based compound, a photoreactive monomer and a photoinitiator system, and optionally added additives uniformly dispersed within the crosslinked polymer matrix.

[0166] Subsequently, when the photopolymer layer is irradiated with a coherent laser during the optical information recording stage, polymerization of photoreactive monomers occurs in regions where reinforcement interference occurs, forming a photopolymer. In regions where cancellation interference occurs, polymerization of photoreactive monomers does not occur or is suppressed, resulting in the presence of photoreactive monomers. The unreacted photoreactive monomers then diffuse towards the photopolymer side where the concentration of photoreactive monomers is lower, causing refractive index modulation, which generates a diffraction grating. As a result, a hologram, i.e., optical information, is recorded on the photopolymer layer having the diffraction grating.

[0167] The method for manufacturing a holographic recording medium according to the further embodiment described above may additionally include a step of photobleaching, in which the photopolymer layer on which the optical information is recorded is irradiated with light to bleach it, after the step of recording the optical information.

[0168] In the photobleaching step, ultraviolet light is irradiated onto the photopolymer layer on which optical information is recorded to terminate the reaction of photoreactive monomers remaining in the photopolymer layer and remove the color of the photosensitive dye. For example, in the photobleaching step, ultraviolet light (UVA) in the 320nm to 400nm range is irradiated to terminate the reaction of photoreactive monomers and remove the color of the photosensitive dye.

[0169] On the other hand, according to yet another embodiment of the invention, an optical element including the holographic recording medium is provided.

[0170] Specific examples of the optical elements include smart devices such as mobile devices, components for wearable displays, vehicle accessories (e.g., head-up displays), holographic fingerprint recognition systems, optical lenses, mirrors, deflection mirrors, filters, diffusion screens, diffraction members, light guides, waveguides, projection screens and / or masks, media and light diffusion plates for optical memory systems, optical wavelength dividers, reflective and transmissive color filters, and the like.

[0171] An example of an optical element including the hologram recording medium is a hologram display device. The hologram display device includes a light source, an input unit, an optical system, and a display unit.

[0172] Specifically, the light source unit is the part that emits a laser beam used to provide, record, and reproduce three-dimensional image information of an object in the input unit and the display unit.

[0173] The aforementioned input unit is the part that pre-inputs three-dimensional image information of an object to be recorded on the display unit. Specifically, it is the part that can input three-dimensional information of an object, such as the intensity and phase of light in different spaces, to an electrically driven liquid crystal (SLM), and at this time, the input beam can be used.

[0174] The optical system may consist of mirrors, polarizers, beam splitters, beam shutters, lenses, and the like. The optical system can distribute the laser beam emitted from the light source to an input beam sent to the input unit, a recording beam sent to the display unit, a reference beam, an erase beam, a readout beam, and the like.

[0175] The display unit receives three-dimensional image information of an object from the input unit, records it on a hologram plate made of an optically addressed SLM (optically driven SLM), and can reproduce the three-dimensional image of the object. At this time, the three-dimensional image information of the object can be recorded by the interference of the input beam and the reference beam. The three-dimensional image information of the object recorded on the hologram plate can be reproduced as a three-dimensional image by the diffraction pattern generated by the readout beam, and the erase beam can be used to quickly remove the formed diffraction pattern. On the other hand, the hologram plate can move between the input position and the playback position of the three-dimensional image. [Effects of the Invention]

[0176] A holographic recording medium according to one embodiment of the invention, by satisfying a specific ratio of elemental composition, not only exhibits excellent optical recording properties but also shows excellent durability against heat and moisture, as well as suitable adhesion to transparent adhesives and high transparency. [Brief explanation of the drawing]

[0177] [Figure 1] This diagram schematically shows the setup of a recording device for hologram recording. Specifically, Figure 1 schematically shows the process in which a laser of a predetermined wavelength is irradiated from a light source 10, and then irradiated onto a PP (hologram recording medium) 80 located on one side of the mirror 70, after passing through mirrors 20, 20', iris 30, spatial filter 40, iris 30', collimation lens 50, and polarized beam splitter (PBS) 60. [Modes for carrying out the invention]

[0178] The function and effects of the invention will be explained in more detail below through specific embodiments of the invention. However, these are presented as examples of the invention and do not limit the scope of the invention's rights in any way.

[0179] In the following manufacturing examples, examples, and comparative examples, the content of raw materials, etc., refers to the content based on solid content unless otherwise specified.

[0180] (Manufacturing Example 1: Manufacturing of (meth)acrylic polyols) In a 2L jacketed reactor, 132g of butyl acrylate, 420g of ethyl acrylate, and 48g of hydroxybutyl acrylate were added and diluted with 1200g of ethyl acetate. The reaction temperature was set to 60°C to 70°C, and stirring was carried out for 30 minutes to 1 hour. 0.42g of n-dodecyl mercaptan (n-DDM) was added, and stirring was continued for another 30 minutes. Thereafter, 0.24g of the polymerization initiator AIBN was added, and polymerization was carried out at the reaction temperature for 4 hours or more until the residual acrylate content was less than 1%, thereby producing a (meth)acrylate copolymer with hydroxyl groups located in branched chains (weight-average molecular weight approximately 300,000, OH equivalent approximately 1802g / equivalent).

[0181] (Manufacturing Example 2: Manufacturing of fluorinated compounds) 20.51 g of 2,2'-(oxybis((1,1,2,2-tetrafluoroethane-2,1-diyl)oxy))bis(2,2-difluoroethan-1-ol) was added to a 1000 mL flask, then dissolved in 500 g of tetrahydrofuran. While stirring at 0°C, 4.40 g of sodium hydroxide (60% dispersion in mineral oil) was carefully added in several additions. After stirring at 0°C for 20 minutes, 12.50 mL of 2-methoxyethoxymethyl chloride was gradually added dropwise. After confirming that all reactants had been consumed by 1H NMR, a work-up using dichloromethane yielded 29 g of a liquid product with a purity of over 95% in 98% yield. The weight-average molecular weight of the prepared fluorinated compound was 586, and the refractive index measured with an Abbe refractometer was 1.361.

[0182] (Example 1: Manufacturing of holographic recording media) (1) Production of photopolymer compositions Trimethylsilyl-terminated poly(methylhydrosiloxane) (manufactured by Sigma-Aldrich, number-average molecular weight: approximately 390, SiH equivalent: approximately 103 g / equivalent), a siloxane polymer, and the (meth)acrylic polyol produced in Production Example 1 were mixed first. The (meth)acrylic polyol content was 17.95 g, and the siloxane polymer was added so that the SiH / OH molar ratio was 2. In Example 1, 2.05 g of the siloxane polymer was added.

[0183] Then, 50 g of HR6042 (Miwon, refractive index 1.60) as a photoreactive monomer, 0.2 g of the compound represented by the following chemical formula a (Chemical Formula 12) as a photosensitive dye, 0.8 g of hexadecyldimethylbenzylammonium tri(p-chlorophenyl)butyl borate as a co-initiator, 0.05 g of H-Nu254 (Spectra), 0.9 g of Irgacure369 as a photoinitiator, 30 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 in a paste mixer for about 30 minutes while blocking out light. Subsequently, 0.014 g of Karstedt (Pt-based) catalyst was added for matrix crosslinking to produce a photopolymer composition.

[0184] [ka]

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

[0186] A diffraction grating was recorded using the setup shown in Figure 1. Specifically, after laminating the manufactured photopolymer layer onto a mirror, irradiating it with a laser allows for the recording of a Notch filter hologram with periodic refractive index modulation in the thickness direction due to the interference between the incident light L and the light L' reflected by the mirror. In this example, the Notch filter hologram was recorded with an incident angle of 0° (degree). The Notch filter and Bragg reflector are optical elements that reflect only light of a specific wavelength, and have a structure in which two layers with a difference in refractive index are periodically stacked to a constant thickness.

[0187] (Examples 2-4 and Comparative Examples 1-5: Manufacturing of Holographic Recording Media) A holographic recording medium was manufactured in the same manner as in Example 1, except that the component amounts of the photopolymer composition were varied as shown in Table 1 below.

[0188] [Table 1]

[0189] (1) Element ratio The elemental ratios on the surface of the pre-recording and post-recording samples were analyzed using the method described below.

[0190] Specifically, the sample to be analyzed was fixed to copper foil with carbon tape, placed on a sample holder, and secured with a clip. Data was then obtained using an X-ray photoelectron spectrometer (ESCA, model name: K-Alpha+, Thermo Fisher Scientific Inc.) according to the K-Alpha+ standard operating procedure (SOP-0524-Ok), and the elemental ratio (atomic %) of the sample surface was analyzed using Avantage software (version 5.980).

[0191] The system specifications of the ESCA equipment used are as follows:

[0192] -Base chamber pressure:1.0×10 -9 mbar -X-ray source:monochromatic Al Kα(1486.6eV) -X-ray spot size: 400μm -Mode:CAE(Constant Analyzer Energy)mode -Charge compensation:Flood gun(FG03:100μA, 0.5V) For the surface of the as-received analysis target sample, an initial survey scan was performed under the following conditions to conduct qualitative analysis, and quantitative analysis was carried out by narrow scan (snap) for each element according to the qualitative analysis results. The elemental ratios at three locations per sample were confirmed, and the peak background smart method was applied for quantitative analysis. The binding energy correction of the core level spectrum was based on C 1s (284.8 eV).

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

[0194] (2) Diffraction efficiency (DE) The diffraction efficiency (η) was obtained by the following formula 1 (Equation 2).

[0195]

number

[0196] In the above equation 1, η is the diffraction efficiency, and P D This is the output power (mW / cm²) of the diffracted beam of the sample after recording. 2 ) and P T This is the output power (mW / cm²) of the beam transmitted through the sample after recording. 2 )

[0197] (3) Heat resistance (ΔDE) The heat resistance was evaluated by the degree of change in diffraction efficiency (ΔDE) before and after exposure to high temperatures. Specifically, after recording a diffraction grating on a sample before recording that was not exposed to high temperatures and on a sample before recording that was exposed to high temperatures, the heat resistance was evaluated by the degree of change in diffraction efficiency, and the degree of change in diffraction efficiency was determined using Equation 2 above.

[0198] In Equation 2 above, DE0 is the diffraction efficiency measured for a sample after it has been stored in a dark room under constant temperature and humidity conditions of 20°C to 25°C and 40RH% to 50RH% before recording, and DE1 is the diffraction efficiency measured for a sample after it has been stored in a dark room under high temperature conditions of 60°C to 70°C and 40RH% to 50RH% before recording, and then recording.

[0199] The diffraction grating was recorded using the method described in Example 1, and the diffraction efficiency was determined by Equation 1 above.

[0200] (4) Moisture and heat resistance (Δλ) For samples with recorded diffraction gratings, the wavelength showing maximum reflectance (i.e., minimum transmittance) under room temperature and non-high humidity conditions was analyzed. A UV-Vis spectrometer was used for the analysis, and the analysis wavelength range was 300 nm to 1,200 nm.

[0201] Subsequently, the same sample was stored for 72 hours at a temperature of 60°C and a humidity of 90 RH, and the wavelength showing the maximum reflectance (minimum transmittance) was analyzed using the same method.

[0202] The heat and humidity resistance of the sample was confirmed by the degree of wavelength shift (Δλ) indicating the maximum reflectance before and after exposure to high temperature and high humidity conditions. A smaller absolute value of the degree of wavelength shift (Δλ) indicating the maximum reflectance indicates better heat and humidity resistance of the sample.

[0203] (5)OCA adhesive strength The diffraction grating was recorded on the sample, which was then cut to a width of 25 mm. The photopolymer layer of the cut sample was laminated with an optically clear adhesive (OCA) tesa® 61563 (thickness: 50 μm, TESA Corporation), and then bonded to a glass base plate.

[0204] The adhesive strength of the photopolymer layer attached to OCA was measured using a texture analyzer (LLOYD). The peel angle during adhesive strength measurement was 180°, and the peel speed was approximately 5 mm / sec.

[0205] (6) Hayes A 5cm x 5cm test specimen was prepared from a sample on which diffraction gratings were recorded. The haze of the test specimen was measured using a haze measuring instrument (HM-150, A light source, Murakami Co., Ltd.) in accordance with JIS K 7136. The haze measurement was performed a total of three times, and the average value was calculated to determine the haze value of the sample.

[0206] [Table 2]

[0207] The elemental ratios on the surface of the sample were measured before and after recording, and the results showed that the elemental ratios on the sample surface were identical before and after recording.

[0208] Referring to Table 2 above, it can be seen that if the fluorine ratio is low, as in Comparative Example 1, diffraction efficiency, heat resistance, and haze are poor, and if the fluorine ratio is high, as in Comparative Example 4, adhesion is reduced. Furthermore, it can be seen that if the silicon ratio is excessively high, as in Comparative Example 2, diffraction efficiency is poor, and if the silicon ratio is excessively low, heat resistance and haze are poor, as in Comparative Example 3, or heat resistance is poor, as in Comparative Example 5.

[0209] In contrast, a holographic recording medium according to one embodiment of the invention has been confirmed to have excellent diffraction efficiency, heat resistance, heat and humidity resistance, adhesion to OCA, and transparency, by satisfying a predetermined elemental ratio.

Claims

1. The photopolymer layer comprises a polymer matrix or precursor formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)acrylic polyol, a photoreactive monomer, a photoinitiator system or a photopolymer obtained therefrom, and a fluorine-based compound. A holographic recording medium wherein, with respect to the total amount of carbon, nitrogen, oxygen, fluorine, and silicon atoms confirmed by photoelectron spectroscopy on the surface of the photopolymer layer, the elemental ratio of carbon is 50 to 70 atoms, the elemental ratio of nitrogen is 0.01 to 2 atoms, the elemental ratio of oxygen is 15 to 30 atoms, the elemental ratio of fluorine is 3 to 12 atoms, and the elemental ratio of silicon is 3 to 15 atoms.

2. The siloxane polymer comprises a repeating unit represented by the following chemical formula 1 (Chemical Formula 1) and an end group represented by the following chemical formula 2 (Chemical Formula 2), 【Chemistry 1】 In the aforementioned chemical formula 1, Multiple R １ and R ２ These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. n is an integer between 1 and 10,000. 【Chemistry 2】 In the aforementioned chemical formula 2, Multiple R １１ ~R １３ These are either identical or different from each other, and each is independently hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms. R of either one of the repeating units represented by chemical formula 1 and the terminal group represented by chemical formula 2 １ , R ２ and R １１ ~R １３ The holographic recording medium according to claim 1, wherein at least one of the elements is hydrogen.

3. The holographic recording medium according to claim 1, wherein the (meth)acrylic polyol is a polymer having a structure in which a hydroxyl group is bonded to the main chain or side chain of a (meth)acrylate polymer.

4. The holographic recording medium according to claim 1, wherein the molar ratio of the silane functional group of the siloxane polymer to the hydroxyl group of the (meth)acrylic polyol is 1.5 to 4.

5. The photoreactive monomer is one or more monofunctional monomers 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; one or more polyfunctional monomers selected from the group consisting of bisphenol A (ethylene oxide) ２～１０ di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisfluorenyl (meth)acrylate, modified bisphenol fluorenyl (meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, phenol novolak epoxy (meth)acrylate, and cresol novolak epoxy (meth)acrylate; or a mixture of two or more thereof. The hologram recording medium according to claim 1.

6. The hologram recording medium according to claim 1, wherein the photoreactive monomer is contained in an amount of 50 to 300 parts by weight per 100 parts by weight of the polymer matrix.

7. The holographic recording medium according to claim 1, wherein the photoinitiator system comprises a photosensitive dye and a coinitiator.

8. The aforementioned photosensitive dye contains a silicon rhodamine compound represented by the following chemical formula 3 (Chemical Formula 3): 【Transformation 3】 In the aforementioned chemical formula 3, R ２１ ~R ２９ Each of these is independently a hydrogen atom, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, or a substituted or unsubstituted C6-C30 aryloxy group. d and e are each independent integers between 0 and 3. f is an integer between 0 and 5. An － The holographic recording medium according to claim 7, wherein is an anion.

9. The aforementioned co-initiator contains a borate anion represented by the following chemical formula 4 (Chemical Formula 4), 【Chemistry 4】 In the aforementioned chemical formula 4, X １ ~X ４ Each of these is independently a substituted or unsubstituted C1-C20 alkyl group, a C2-C20 alkenyl group, a C6-C30 aryl group, a C7-C30 arylalkyl group, a C7-C30 alkylaryl group, or an allyl group, and X １ ~X ４ The holographic recording medium according to claim 7, wherein at least one of the groups is not an aryl group.

10. The hologram recording medium according to claim 1, wherein the fluorine-based compound is contained in an amount of 20 to 200 parts by weight per 100 parts by weight of the polymer matrix.

11. The hologram recording medium according to claim 1, wherein the photopolymer layer comprises 17% to 38% by weight of the polymer matrix, 36% to 58% by weight of the photoreactive monomer, and 17% to 38% by weight of the fluorine-based compound, based on the total weight of the polymer matrix, photoreactive monomer, and fluorine-based compound.

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

13. The diffraction efficiency change value ΔDE, calculated using the following equation 2 (equation 1), is 10% or less. [Math 1] In the above formula 2, DE ０ This is the diffraction efficiency measured for a hologram recording medium on which a Notch filter hologram was recorded, after the hologram recording medium was stored in a dark room under constant temperature and humidity conditions of 20°C to 25°C and 40 RH to 50 RH. １ The hologram recording medium according to claim 1, wherein the diffraction efficiency is measured for a hologram recording medium on which a Notch filter hologram has been recorded, after the hologram recording medium has been stored in a dark room under high temperature conditions of 60°C to 70°C and 40 RH% to 50 RH.

14. The holographic recording medium according to claim 1, wherein the degree of wavelength shift exhibiting the maximum reflectance before and after 72 hours of storage at a temperature of 60°C and a relative humidity of 90% is -10 nm to 10 nm.

15. The hologram recording medium according to claim 1, wherein the adhesive strength of the photopolymer layer to the optically transparent adhesive is 1000 gf / 25 mm or more.

16. The hologram recording medium according to claim 1, wherein the haze is 3% or less.

17. A step of forming a photopolymer layer by applying a photopolymer composition comprising a polymer matrix or its precursor formed by crosslinking a siloxane polymer containing a silane functional group and a (meth)acrylic polyol, a fluorine compound, a photoreactive monomer, and a photoinitiator system, The process includes irradiating a predetermined region of the photopolymer layer with a coherent laser to selectively polymerize the photoreactive monomers contained in the photopolymer layer and record optical information. A method for manufacturing a hologram recording medium, wherein the photopolymer layer has an elemental ratio of 50 to 70 atoms, a nitrogen elemental ratio of 0.01 to 2 atoms, a oxygen elemental ratio of 15 to 30 atoms, a fluorine elemental ratio of 3 to 12 atoms, and a silicon elemental ratio of 3 to 15 atoms, relative to the total amount of carbon, nitrogen, oxygen, fluorine, and silicon atoms confirmed on its surface by photoelectron spectroscopy.

18. The method for producing a hologram recording medium according to claim 17, wherein the photopolymer composition contains a Pt-based catalyst, and the Pt-based catalyst is present in an amount of 0.01 to 0.30 parts by weight per 100 parts by weight of (meth)acrylic polyol.

19. A method for manufacturing a hologram recording medium according to claim 17, wherein in the step of forming the photopolymer layer, the coating film formed by applying the photopolymer composition is dried at 50°C to 120°C.

20. An optical element comprising a holographic recording medium as described in claim 1.

Images