Hologram recording medium and optical element including same

Abstract

The invention relates to a hologram recording medium and an optical element including the same. The hologram recording medium not only has excellent optical recording characteristics, but also can exhibit transparent optical characteristics and can exhibit excellent reliability even in high-temperature and high-humidity environments.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2022-0146043 filed on November 4, 2022, and Korean Patent Application No. 10-2022-0146044 filed on November 4, 2022, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety.

[0003] The present invention relates to a hologram recording medium and an optical element including the same. Background Art

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

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

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

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

[0008] Recently, demands for development of materials capable of maintaining a stable hologram at high diffraction efficiency have increased, and various attempts have been made to prepare a photopolymer layer having high diffraction efficiency and a high refractive index modulation value and a thin thickness.

[0009] On the other hand, when the hologram recording medium is used as an optical element in an application such as a mobile device or a vehicle component (e.g., a head-up display), it is placed in a high temperature and high humidity environment. In such a case, when the diffraction grating is deformed, the image becomes distorted and the originally intended function may not be performed. Therefore, it is necessary to develop a photopolymer layer and a hologram recording medium including the same, in which the diffraction grating of the photopolymer layer is less deformed despite the heat and moisture of the use environment and has excellent reliability. Summary of the invention

[0010] Technical issues

[0011] According to one embodiment of the present invention, there is provided a hologram recording medium.

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

[0013] Technical Solution

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

[0015] Unless otherwise specifically stated, the term "hologram recording medium" as used herein means a medium on which optical information can be recorded in the entire visible light range and ultraviolet range (e.g., 300 nm to 1200 nm) via an exposure process. Therefore, the hologram recording medium herein may mean a medium on which optical information is recorded, or may mean a medium before recording that is capable of recording optical information. The hologram herein may include all visual holograms, such as on-axis (Gabor) holograms, off-axis holograms, full aperture transfer holograms, white light transmission holograms ("rainbow holograms"), Denisyuk holograms, off-axis reflection holograms, edge-illuminated holograms, or holographic stereograms.

[0016] In this specification, with respect to environmental conditions in which a hologram recording medium or a device including the same is placed, etc., "high temperature" may mean a temperature of 60°C or higher. For example, high temperature may mean a temperature of 65°C or higher, 70°C or higher, 75°C or higher, 80°C or higher, 85°C or higher, or 90°C or higher, and its upper limit is not particularly limited, but may be, for example, 110°C or lower, 105°C or lower, 100°C or lower, 95°C or lower, 90°C or lower, 85°C or lower, or 80°C or lower. When temperature affects the characteristics of a material, an object, or a component, unless the temperature is specifically mentioned otherwise, the temperature condition for measuring or describing the characteristics may mean room temperature (for example, a temperature in the range of about 15°C to 30°C, which is a temperature without heating or cooling).

[0017] In addition, in this specification, with respect to the environmental conditions in which the hologram recording medium or the device including the same is placed, etc., "high humidity" may mean a relative humidity of 80% or more. For example, a high humidity condition may mean a condition satisfying a relative humidity of 85% or more, 90% or more, or 95% or more. When humidity affects the properties of a material, an object or a component, unless otherwise specifically stated, the humidity condition for measuring or describing the properties is a condition in which the relative humidity is lower than the high humidity condition. For example, it may be a relative humidity condition within the range of 15% or more and less than 80%, specifically, it refers to a relative humidity condition with a lower limit of 20% or more, 25% or more, 30% or more, 35% or more, and 40% or more and an upper limit of 75% or less, 70% or less, 65% or less, or 60% or less.

[0018] Furthermore, in the present specification, the high temperature / high humidity condition may mean an environmental condition that satisfies at least one of the above-mentioned high temperature condition and high humidity condition.

[0019] According to one embodiment of the present invention, a hologram recording medium is provided, which includes a photopolymer layer, the photopolymer layer comprising: a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorinated compound, wherein the refractive index change rate calculated by the following equation 4 is 1.0% or less, and wherein the haze is 2% or less.

[0020] [Equation 4]

[0021] Refractive index change rate (%) = {|1-n1 / n0|}×100

[0022] Wherein, in Equation 4, n0 is the refractive index of the sample in which the hologram recording medium before recording was stored at a temperature of 20°C to 25°C and a relative humidity of 40% to 50% and then bleached with a white LED, and n1 is the refractive index of the sample in which the hologram recording medium before recording was stored at a temperature of 60°C and a relative humidity of 90% for 72 hours and then bleached with a white LED.

[0023] The present inventors have found that, when a specific photopolymer layer is included, a hologram recording medium can be provided that exhibits not only improved optical recording characteristics but also highly reliable and highly transparent optical characteristics even in a high temperature / high humidity environment, and have completed the present invention.

[0024] A hologram recording medium and an optical element including the hologram recording medium according to an embodiment of the present invention will be described in detail below.

[0025] A hologram recording medium according to one embodiment of the present invention includes a photopolymer layer, which contains: a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorinated compound.

[0026] The photopolymer layer may be a photopolymer layer in a state before recording in which optical information can be recorded, or may be a photopolymer layer in a state in which optical information is recorded.

[0027] A photopolymer layer on which optical information is recorded can be prepared by irradiating object light and reference light onto the photopolymer layer before recording. When the object light and reference light are irradiated onto the photopolymer layer before recording, due to the interference field between the object light and the reference light, the photoinitiator system exists in an inactive state in the destructive interference region, and photopolymerization of the photoreactive monomer does not occur, while in the constructive interference region, photopolymerization of the photoreactive monomer occurs due to the activated photoinitiator system. As the photoreactive monomer is continuously consumed in the constructive interference region, a concentration difference occurs between the photoreactive monomers in the destructive interference region and the constructive interference region. Therefore, the photoreactive monomers in the destructive interference region diffuse into the constructive interference region. At this time, the fluorinated compound, which is a plasticizer, moves in the opposite direction to the photoreactive monomer. Since the photoreactive monomer and the photopolymer formed therefrom have a high refractive index compared to the polymer matrix and the fluorinated compound, a spatial change in the refractive index occurs in the photopolymer layer, and a grating is generated by the spatial refractive index modulation occurring in the photopolymer layer. Such a grating surface acts as a reflective surface that reflects incident light due to the difference in refractive index. When light with the wavelength at the time of recording is incident in the direction of the reference light after recording the hologram, it satisfies the Bragg condition and the light is diffracted in the direction of the original object light, which reproduces the holographic optical information.

[0028] Thus, if the photopolymer layer is in a state before recording, the photopolymer layer may comprise the photoreactive monomer, the photoinitiator and the fluorinated compound in a randomly dispersed form within a polymer matrix or a precursor thereof.

[0029] On the other hand, if the optical information is recorded on a photopolymer layer, the photopolymer layer may include a polymer matrix, a photopolymer distributed to form a grating, and a fluorinated compound.

[0030] The photopolymer layer is formed of a photopolymer composition comprising: a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol or a precursor thereof; a photoreactive monomer and a photoinitiator system; and a fluorinated compound.

[0031] The polymer matrix is ​​used as a support for the photopolymer layer and is formed by crosslinking a siloxane-based polymer containing a silane functional group (Si-H) and a (meth) acrylic polyol. Specifically, the polymer matrix is ​​formed by crosslinking a (meth) acrylic polyol with a siloxane-based polymer containing a silane functional group. More specifically, the hydroxyl group of the (meth) acrylic polyol can form a crosslink with the silane functional group of the siloxane-based polymer through a hydrosilylation reaction. The hydrosilylation reaction can be carried out rapidly even at room temperature (e.g., at a temperature in the range of about 15°C to 30°C, which is a temperature without heating or cooling) under a Pt-based catalyst. Therefore, a hologram recording medium according to an embodiment of the present invention uses a polymer matrix that can be quickly crosslinked even at room temperature as a support, thereby being able to improve preparation efficiency and productivity.

[0032] The polymer matrix can enhance the mobility of components (e.g., photoreactive monomers or plasticizers, etc.) contained in the photopolymer layer due to the flexible main chain of the siloxane-based polymer. In addition, the siloxane bond having excellent heat resistance and wet heat resistance characteristics can help ensure the reliability of the photopolymer layer recording optical information and the hologram recording medium including the same.

[0033] The polymer matrix can have a relatively low refractive index, which can be used to enhance the refractive index modulation of the photopolymer layer. For example, the upper limit of the refractive index of the polymer matrix can be 1.53 or less, 1.52 or less, 1.51 or less, 1.50 or less, or 1.49 or less. In addition, the lower limit of the refractive index of the polymer matrix can be, for example, 1.40 or greater, 1.41 or greater, 1.42 or greater, 1.43 or greater, 1.44 or greater, 1.45 or greater, or 1.46 or greater. As used herein, "refractive index" can be a value measured at 25°C using an Abbe refractometer.

[0034] The photopolymer layer may include the polymer matrix in a cross-linked form as described above, or may include a precursor thereof. When the photopolymer layer includes a precursor of the polymer matrix, it may include a siloxane-based polymer, a (meth)acrylic polyol, and a Pt-based catalyst.

[0035] The siloxane-based polymer may include, for example, a repeating unit represented by the following Chemical Formula 1 and a terminal group represented by the following Chemical Formula 2.

[0036] [Chemical formula 1]

[0037]

[0038] Wherein, in Chemical Formula 1,

[0039] Plural R 11and R 12 are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and

[0040] k is an integer from 1 to 10,000,

[0041] [Chemical formula 2]

[0042]

[0043] Wherein, in Chemical Formula 2,

[0044] Plural R 13 To R 15 are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and

[0045] R is selected from at least one repeating unit among the repeating units represented by Chemical Formula 1 and any one terminal group among the terminal groups represented by Chemical Formula 2. 11 To R 15 At least one of them is hydrogen.

[0046] In Chemical Formula 2, -(O)- means that when Si of the terminal group represented by Chemical Formula 2 is bonded to the repeating unit represented by Chemical Formula 1, it is bonded through oxygen (O) or directly bonded without oxygen (O).

[0047] As used herein, "alkyl" can be a straight chain alkyl, a branched chain alkyl, or a cyclic alkyl. As a non-limiting example, "alkyl" as used herein can be methyl, ethyl, propyl (e.g., n-propyl, isopropyl, etc.), butyl (e.g., n-butyl, isobutyl, tert-butyl, sec-butyl, cyclobutyl, etc.), pentyl (e.g., n-pentyl, isopentyl, neopentyl, tert-pentyl, 1,1-dimethyl-propyl, 1-ethyl-propyl, 1-methyl-butyl, cyclopentyl, etc.), hexyl (e.g., n-hexyl, 1-methylpentyl, 2-methylpentyl, etc.), cyclopentyl, etc.), cyclopentyl, etc.), methyl butyl, propyl, 1-ethyl-propyl, 1-methyl-butyl, cyclopentyl, etc.), methyl butyl, propyl, 1-methyl-butyl, 1-methyl-pentyl, 1-methyl-butyl ... The invention also includes but is not limited to cyclopentyl, 4-methylpentyl, 3,3-dimethylbutyl, 1-ethyl-butyl, 2-ethylbutyl, cyclopentylmethyl, cyclohexyl, etc.), heptyl (for example, n-heptyl, 1-methylhexyl, 4-methylhexyl, 5-methylhexyl, cyclohexylmethyl, etc.), octyl (for example, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, etc.), nonyl (for example, n-nonyl, 2,2-dimethylheptyl, etc.), and the like.

[0048] In one embodiment, R in Chemical Formula 1 and Chemical Formula 2 11 To R 15 is methyl or hydrogen, and R 11 To R 15At least two of them may be hydrogen. More specifically, the siloxane-based polymer may be one in which R 11 and R 12 are each independently methyl and hydrogen, and R 13 To R 15 A compound in which each independently is a methyl group or a hydrogen group (for example, a polymethylhydrogensiloxane whose terminal group is a trimethylsilyl group or a dimethylhydrogensilyl group); wherein some R 11 and R 12 are methyl and hydrogen respectively, and the remaining R 11 and R 12 are all methyl groups, and R 13 To R 15 A compound in which each independently is a methyl group or a hydrogen group (for example, a poly(dimethylsiloxane-co-methylhydrogensiloxane) whose terminal group is a trimethylsilyl group or a dimethylhydrogensilyl group); or a compound in which R 11 and R 12 Both are methyl groups. R 13 To R 15 A compound in which at least one of the terminal groups is hydrogen and the others are each independently methyl or hydrogen (for example, a polydimethylsiloxane in which either or both of the terminal groups are dimethylhydrogensilyl groups).

[0049] As an example, the number average molecular weight (Mn) of the siloxane-based compound may be in the range of 200 to 4,000. Specifically, the lower limit of the number average molecular weight of the siloxane-based polymer may be, for example, 200 or more, 250 or more, 300 or more, or 350 or more, and the upper limit thereof may be, for example, 3,500 or less, 3,000 or less, 2,500 or less, 2,000 or less, 1,500 or less, or 1,000 or less. When the number average molecular weight of the siloxane-based polymer satisfies the above range, the following problems can be prevented, thereby making the hologram recording medium formed by the photopolymer composition exhibit excellent optical recording characteristics and excellent durability under high temperature / high humidity conditions: during the crosslinking process with (meth) acrylic polyol at room temperature or higher, the siloxane-based polymer volatilizes and the matrix crosslinking degree decreases, or the siloxane-based polymer has poor compatibility with other components of the photopolymer composition, and thus phase separation occurs between the components.

[0050] The number average molecular weight means the number average molecular weight (unit: g / mol) according to polystyrene determined by the GPC method. In the process of determining the number average molecular weight according to polystyrene measured by the GPC method, known analytical devices, detectors such as refractive index detectors and analytical columns can be used, and commonly used temperature, solvent and flow conditions can be used. Specific examples of measurement conditions can include a temperature of 25° C., a tetrahydrofuran solvent, and a flow rate of 1 mL / min.

[0051] (Meth) acrylic polyol may refer to a polymer in which one or more, specifically two or more, hydroxyl groups are bonded to the main chain or side chain of a (meth) acrylate-based polymer. Unless otherwise specifically stated, "(meth) acrylic" as used herein refers to acrylic and / or methacrylic, which is a term covering all acrylics, methacrylics, or mixtures of acrylics and methacrylics.

[0052] The (meth) acrylic polyol is a homopolymer of a (meth) acrylate-based monomer having a hydroxyl group, a copolymer of two or more types of (meth) acrylate-based monomers having a hydroxyl group, or a copolymer of a (meth) acrylate-based monomer having a hydroxyl group and a (meth) acrylate-based monomer not having a hydroxyl group. Unless otherwise specified, "copolymer" as used herein is a term covering all random copolymers, block copolymers, and graft copolymers.

[0053] The (meth)acrylate-based monomer having a hydroxyl group may include, for example, hydroxyalkyl (meth)acrylate, hydroxyaryl (meth)acrylate, etc., the alkyl group is an alkyl group having 1 to 30 carbon atoms, and the aryl group may be an aryl group having 6 to 30 carbon atoms. In addition, the (meth)acrylate-based monomer not having a hydroxyl group may include, for example, a (meth)acrylate-based monomer, a (meth)acrylate-based monomer, etc., the alkyl group may be an alkyl group having 1 to 30 carbon atoms, and the aryl group may be an aryl group having 6 to 30 carbon atoms.

[0054] As an example, the weight average molecular weight (Mw) of (meth) acrylic polyol can be in the range of 150,000 to 1,000,000. The weight average molecular weight means the weight average molecular weight according to polystyrene measured by the GPC method as described above. For example, the lower limit of the weight average molecular weight can be 150,000 or more, 200,000 or more, or 250,000 or more, and its upper limit can be, for example, 900,000 or less, 850,000 or less, 800,000 or less, 750,000 or less, 700,000 or less, 650,000 or less, 600,000 or less, 550,000 or less, 500,000 or less, or 450,000 or less. When the weight average molecular weight of the (meth)acrylic polyol satisfies the above range, the polymer matrix fully exerts its function as a support, and therefore the recording properties of optical information are less reduced even after the use time has passed, and sufficient flexibility is imparted to the polymer matrix, thereby being able to improve the mobility of components contained in the photopolymer composition (for example, photoreactive monomers or plasticizers, etc.) and minimize the reduction in the recording properties of optical information.

[0055] In order to adjust the crosslinking density of the (meth)acrylic polyol through the siloxane-based polymer to a level conducive to ensuring the function of the hologram recording medium, the hydroxyl equivalent of the (meth)acrylic polyol may be adjusted to an appropriate level.

[0056] Specifically, the hydroxyl (-OH) equivalent of the (meth) acrylic polyol may be, for example, in the range of 500 g / equivalent to 3000 g / equivalent. More specifically, the lower limit of the hydroxyl (-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. In addition, the upper limit of the hydroxyl (-OH) equivalent of (meth) acrylic polyol can be 2900g / equivalent or less, 2800g / equivalent or less, 2700g / equivalent or less, 2600g / equivalent or less, 2500g / equivalent or less, 2400g / equivalent or less, 2300g / equivalent or less, 2200g / equivalent or less, 2100g / equivalent or less, 2000g / equivalent or less, or 1900g / equivalent or less. The hydroxyl (-OH) equivalent of (meth) acrylic polyol is the equivalent (g / equivalent) of one hydroxyl functional group, which is the value obtained by dividing the weight average molecular weight of (meth) acrylic polyol by the number of hydroxyl functional groups per molecule. As the equivalent value is smaller, the functional group density is higher, and as the equivalent value is larger, the functional group density is smaller. When the hydroxyl (-OH) equivalent of the (meth) acrylic polyol satisfies the above range, the polymer matrix has an appropriate cross-linking density and thus fully serves as a support, and the mobility of the components contained in the photopolymer layer is improved, which allows the initial refractive index modulation value to be maintained at an excellent level even over time without the problem of boundary surface collapse of the diffraction grating generated after recording, thereby minimizing the reduction in the recording characteristics of the optical information.

[0057] For example, the glass transition temperature (Tg) of the (meth) acrylic polyol may be in the range of -60°C to -10°C. Specifically, the lower limit of the glass transition temperature may be, for example, -55°C or higher, -50°C or higher, -45°C or higher, -40°C or higher, -35°C or higher, -30°C or higher, or -25°C or higher, and the upper limit thereof 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. If the above glass transition temperature range is met, the glass transition temperature may be reduced without significantly reducing the modulus of the polymer matrix, thereby increasing the mobility (fluidity) of other components in the photopolymer composition, and also improving the formability of the photopolymer composition. The glass transition temperature may be measured using known methods such as DSC (Differential Scanning Calorimetry) or DMA (dynamic mechanical analysis).

[0058] 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 thereof 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 above range, it may contribute to improving the refractive index modulation. The refractive index of the (meth) acrylic polyol is a theoretical refractive index and may be calculated using the refractive index of the monomer used to prepare the (meth) acrylic polyol (value measured at 25° C. using an Abbe refractometer) and the fraction (molar ratio) of each monomer.

[0059] (Meth) acrylic polyol and siloxane-based polymer can be used to make the molar ratio (SiH / OH) of the silane functional group (Si-H) of the siloxane-based polymer and the hydroxyl group (-OH) of the (meth) acrylic polyol be 0.80 to 3.5. That is, the type and content of the siloxane-based polymer and the (meth) acrylic polyol can be selected so that the molar ratio is met when forming the polymer matrix. The lower limit of the molar ratio (SiH / OH) can be, for example, 0.81 or greater, 0.85 or greater, 0.90 or greater, 0.95 or greater, 1.00 or greater, or 1.05 or greater, and its upper limit can be, for example, 3.4 or less, 3.3 or less, 3.2 or less, 3.1 or less, 3.05 or less, or 3.0 or less. When the above molar ratio (SiH / OH) range is met, the polymer matrix is ​​cross-linked into an appropriate cross-linking density, so that the reliability under high temperature / high humidity conditions is improved, and sufficient refractive index modulation values ​​can be achieved.

[0060] The Pt-based catalyst may be, for example, a Karstedt catalyst, etc. In addition to the Pt-based catalyst, the precursor of the polymer matrix may optionally include a rhodium-based catalyst, an iridium-based catalyst, a rhenium-based catalyst, a molybdenum-based catalyst, an iron-based catalyst, a nickel-based catalyst, an alkali metal or alkaline earth metal-based catalyst, a Lewis acid-based catalyst or a carbene-based non-metal catalyst.

[0061] On the other hand, the photoreactive monomer may include a compound having a higher refractive index than the polymer matrix to achieve the above-mentioned refractive index modulation. However, all photoreactive monomers included in the photopolymer composition are not limited to those having a higher refractive index than the polymer matrix, and at least a portion of the photoreactive monomers may have a higher refractive index than the polymer matrix to achieve a high refractive index modulation value. In one example, the photoreactive monomer may include a monomer having a refractive index of 1.50 or greater, 1.51 or greater, 1.52 or greater, 1.53 or greater, 1.54 or greater, 1.55 or greater, 1.56 or greater, 1.57 or greater, 1.58 or greater, 1.59 or greater, or 1.60 or greater and 1.70 or less.

[0062] The photoreactive monomer may include at least one monomer selected from a monofunctional monomer having one photoreactive functional group and a multifunctional monomer having two or more photoreactive functional groups. The photoreactive functional group may be, for example, a (meth)acryloyl group, a vinyl group, a thiol group, etc. More specifically, the photoreactive functional group may be a (meth)acryloyl group.

[0063] The monofunctional monomer may include, for example, at least one selected from the group consisting of benzyl (meth)acrylate (M1182 with a refractive index of 1.5140, Miwon Specialty Chemical), benzyl 2-phenylacrylate, phenoxybenzyl (meth)acrylate (M1122 with a refractive index of 1.565, Miwon Specialty Chemical), phenol (ethylene oxide) (meth)acrylate (phenol (EO) (meth)acrylate; M140 with a refractive index of 1.516, Miwon Specialty Chemical), phenol (ethylene oxide) 2 (meth)acrylate (phenol (EO) 2 (meth)acrylate; M142 with a refractive index of 1.510, Miwon Specialty Chemical), o-phenylphenol (ethylene oxide) (meth)acrylate (o-phenylphenol (EO) (meth)acrylate; M1142 with a refractive index of 1.577, Miwon Specialty Chemical), phenylthioethyl (meth)acrylate (M1162 with a refractive index of 1.560, Miwon Specialty Chemical), Specialty Chemical), and biphenyl methyl (meth)acrylate.

[0064] The multifunctional monomer may include, for example, at least one selected from the following: bisphenol A (ethylene oxide) 2～10 Di(meth)acrylate (bisphenol A (EO) 2～10(Meth)acrylates; M240 with a refractive index of 1.537, M241 with a refractive index of 1.529, M244 with a refractive index of 1.545, M245 with a refractive index of 1.537, M249 with a refractive index of 1.542, M2100 with a refractive index of 1.516, M2101 with a refractive index of 1.512, Miwon Specialty Chemical), bisphenol A epoxy di(meth)acrylate (PE210 with a refractive index of 1.557, PE2120A with a refractive index of 1.533, PE2120B with a refractive index of 1.534, PE2020C with a refractive index of 1.539, PE2120S with a refractive index of 1.556, Miwon Specialty Chemical), Chemical), bisphenol fluorene di(meth)acrylate (HR6022 with a refractive index of 1.600, HR6040 with a refractive index of 1.600, HR6042 with a refractive index of 1.600, Miwon Specialty Chemical), modified bisphenol fluorene di(meth)acrylate (HR6060 with a refractive index of 1.584, HR6100 with a refractive index of 1.562, HR6200 with a refractive index of 1.530, Miwon Specialty Chemical), tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate (M370 with a refractive index of 1.508, Miwon Specialty Chemical), phenol novolac epoxy (meth)acrylate (SC6300 with a refractive index of 1.525, Miwon Specialty Chemical), Chemical), and cresol novolac epoxy (meth)acrylate (SC6400 with a refractive index of 1.522, SC6400C with a refractive index of 1.522, Miwon Specialty Chemical).

[0065] Based on 100 parts by weight of the polymer matrix, the photopolymer layer can include the photoreactive monomer in an amount of 50 to 300 parts by weight. For example, the lower limit of the content of the photoreactive monomer can be 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, or 90 parts by weight or more, and its upper limit can be 300 parts by weight or less, 280 parts by weight or less, 250 parts by weight or less, 220 parts by weight or less, 200 parts by weight or less, 190 parts by weight or less, or 180 parts by weight or less. When the above range is met, it is conducive to ensuring excellent optical recording characteristics and durability in high temperature / high humidity environments.

[0066] The content of the polymer matrix herein means the total content (weight) of the (meth) acrylic polyol and the siloxane-based polymer forming the matrix. In other words, the content of the polymer matrix means both the content of the polymer matrix formed by crosslinking the (meth) acrylic polyol and the siloxane-based polymer and the content of the partially uncrosslinked polymer matrix precursor.

[0067] The photopolymer layer comprises a photoinitiator system. The photoinitiator system may mean a photoinitiator, or a combination of a photosensitizer and a co-initiator that enables polymerization initiated by light.

[0068] The photopolymer layer may comprise a photosensitizer and a coinitiator as the photoinitiator system.

[0069] As the photosensitizer, for example, a photosensitizing dye may be used. Specifically, the photosensitizing dye may include, for example, at least one selected from the following: a silicon rhodamine compound, anthra(9,1-bc)naphtho(3,2,1-kl)acridine (ceramidonine), derivatives, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose red, thionine, basic yellow, chlorinated pinacol cyanol, rhodamine 6G, baking cyanine, ethyl violet, Victoria blue R, azure blue, quinaldine red, crystal violet, brilliant green, basic orange G, darrow red, pyronin Y, basic red 29, pyranose I (pyran Iodide), Safranin O, Cyanine, Methylene Blue, Azure A, and BODIPY.

[0070] In one example, as the photosensitizing dye, cyanine dyes Cy3 and Cy5 (H-Nu640, SpectraGroup Limited) may be used, or Safranin O may be used.

[0071] Based on 100 parts by weight of the polymer matrix, the photopolymer layer may contain a photosensitizing dye in a range of 0.01 parts by weight to 10 parts by weight. Specifically, the lower limit of the content of the photosensitizing dye may be, for example, 0.05 parts by weight or more, 0.07 parts by weight or more, or 0.10 parts by weight or more, and the upper limit thereof may be, for example, 5 parts by weight or less. When the above range is met, it is beneficial to exhibit an appropriate polymerization reaction rate and ensure desired optical recording characteristics.

[0072] The coinitiator may be an electron donor, an electron acceptor, or a mixture thereof.

[0073] In one example, the photopolymer layer may include an electron donor as a coinitiator. The electron donor may include, for example, a borate anion represented by the following Chemical Formula 3.

[0074] [Chemical formula 3]

[0075] BX 1 X 2 X 3 X 4

[0076] Wherein, in chemical formula 3, X 1 To X 4 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, provided that X 1 To X 4 At least one of the groups is not an aryl group.

[0077] When an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group is substituted, it may be substituted with at least one selected from halogen and an alkoxy group having 1 to 5 carbon atoms.

[0078] Specifically, X 1 To X 3 may be each independently halogen-substituted or unsubstituted methyl, ethyl, propyl, n-butyl, n-pentyl, n-hexyl, cyclobutyl, cyclopentyl, cyclohexyl, vinyl, propenyl, phenyl, methylphenyl, methoxyphenyl, naphthyl, methylnaphthyl, or methoxynaphthyl, and X 4 It may be an n-butyl group, an n-pentyl group, or an n-hexyl group. More specifically, the borate anion represented by Chemical Formula 3 may be, for example, a triphenylbutylborate anion.

[0079] The cation bonded to the borate anion is a cation that does not absorb light, and may be an alkali metal cation or a quaternary ammonium cation. A quaternary ammonium cation means an ammonium cation in which nitrogen (N) is substituted with four substituents, wherein the four substituents are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms connected by an ester bond (e.g., -CH2CH2-O-CO-CH2CH2CH3, etc.).

[0080] As the electron donor, for example, commercially available butyrylcholine triphenylbutylborate (Borate V, manufactured by Spectra Group) can be used.

[0081] In one example, the photopolymer layer may include an electron acceptor as a co-initiator. The electron acceptor may include, for example Salt, such as Salt, iodine salt, or a mixture thereof.

[0082] In one example, the electron acceptor may include iodine As the electron acceptor, for example, commercially available H-Nu 254 (Spectra Group) can be used.

[0083] The photopolymer layer may contain the coinitiator in a range of 0.05 to 10 parts by weight based on 100 parts by weight of the polymer matrix. Specifically, the lower limit of the content of the coinitiator may be, for example, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, or 0.5 parts by weight or more, and the upper limit thereof may be, for example, 5 parts by weight or less. When the above range is met, it is beneficial to exhibit an appropriate polymerization reaction rate and ensure desired optical recording characteristics.

[0084] The photoinitiator system may contain an additional photoinitiator to remove the color of the photosensitive dye and react all unreacted photoreactive monomers after the light irradiation for recording. The photoinitiator may include, for example, imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxypyridines, salts, thioxanthone derivatives, amine derivatives, diazonium salts, Salt, iodine Salts, sulfonates, imide sulfonates / salts, dialkyl-4-hydroxy Salt, arylsulfonic acid p-nitrobenzyl ester, silanol-aluminum complex, (η6-phenyl)(η5-cyclopentadienyl) iron (II), benzoin toluenesulfonate / salt, 2,5-dinitrobenzyl toluenesulfonate / salt, N-toluenesulfonylphthalimide, or a mixture thereof. More specifically, the photoinitiator may include 1,3-di(tert-butyldioxycarbonyl)benzophenone, 3,3',4,4"-tetra(tert-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isobutylenesulfonate, 1,3-di(tert-butyldioxycarbonyl)benzophenone, 1,3',4,4"-tetra ... oxazolidinone, 2-mercaptobenzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one (product name: Irgacure 651 / manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure 184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure 369 / manufacturer: BASF), bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium (product name: Irgacure 784 / manufacturer: BASF), Ebecryl P-115 (manufacturer: SK Entis), Cyracure UVI-6970, Cyracure UVI-6974, Cyracure UVI-6990 (manufacturer: Dow Chemical Co., USA), Irgacure 264, Irgacure 250 (manufacturer: BASF), CIT-1682 (manufacturer: Nippon Soda), or a mixture thereof, but not limited thereto.

[0085] The photopolymer layer contains a fluorinated compound as a plasticizer.

[0086] Plasticizers make it easier to achieve refractive index modulation during the preparation of hologram recording media. More specifically, plasticizers reduce the glass transition temperature of the polymer matrix, improve the mobility of photoreactive monomers, and have low refractive index and non-reactive properties. Therefore, when the photoreactive monomers uniformly distributed in the polymer matrix but not photopolymerized move, they can move in the opposite direction of the plasticizer and contribute to refractive index modulation. In addition, plasticizers can also help improve the formability of the photopolymer composition.

[0087] The fluorinated compound may have a low refractive index of 1.45 or less to perform the above-mentioned plasticizer function. Specifically, the upper limit of the refractive index 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. Due to the use of a fluorinated compound having a lower refractive index than the above-mentioned photoreactive monomer, the refractive index of the polymer matrix can be further reduced, and the refractive index modulation of the photoreactive monomer can be made greater.

[0088] When the photopolymer layer includes a fluorinated compound represented by the following Chemical Formula 4, a hologram recording medium having excellent optical recording characteristics even in a high temperature / high humidity environment as well as excellent reliability and high transparency can be provided.

[0089] [Chemical formula 4]

[0090]

[0091] Among them, in chemical formula 4,

[0092] Z 1 is -O- or -NH-,

[0093] Z 2 is a single bond, -O-, or -NH-,

[0094] L 1 is a single bond or a divalent to hexavalent organic group in which a hydroxyl group has been removed from a polyol having 2 to 6 hydroxyl groups,

[0095] n and m are each independently an integer from 1 to 5, wherein the sum of n and m is from 2 to 6,

[0096] R 1 is methyl or ethyl, and

[0097] R 2 To R 4 At least one of the fluorine-containing substituents is an alkyl group having 1 to 20 carbon atoms substituted by 2 or more fluorine groups, a cycloalkyl group having 3 to 30 carbon atoms substituted by 2 or more fluorine groups, or an aryl group having 6 to 30 carbon atoms substituted by 2 or more fluorine groups,

[0098] When R 2 and R 3 When it is not a fluorine-containing substituent, R 2 and R 3 each independently represents hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a heterocycloalkyl group having 4 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-, and

[0099] When R 4 When it is not a fluorine-containing substituent, R 4It is an alkyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-.

[0100] More specifically, the fluorinated compound represented by Chemical Formula 4 exhibits a sufficiently low refractive index, and thus can fully function as a basic plasticizer to increase the refractive index modulation of the photoreactive monomer and improve the dispersibility of the components in the photopolymer composition. In addition, the fluorinated compound represented by Chemical Formula 4 is less likely to migrate to the surface of the photopolymer layer even in a high temperature and high humidity environment, is heat and moisture resistant, and is not easily decomposed even under high temperature / high humidity conditions, thereby being able to improve reliability in a high temperature / high humidity environment. In addition, the fluorinated compound represented by Chemical Formula 4 exhibits excellent compatibility with components having a high refractive index, and can ensure highly transparent optical properties due to excellent moisture and heat resistance.

[0101] In chemical formula 4, L 1 The carbonyl-containing part and the R-containing part 4 Therefore, the sum of n and m is 2 to 6, which is equal to L 1 The number of keys in .

[0102] In one example, in Chemical Formula 4, L 1 In chemical formula 4, when L 1 When it is a single bond, n and m are each 1, and Z 2 In this case, the fluorinated compound represented by Chemical Formula 4 may be represented by the following Chemical Formula 4-1.

[0103] [Chemical formula 4-1]

[0104]

[0105] Among them, in chemical formula 4-1,

[0106] Z 1 '、R 1 '、R 2 '、R 3 ' and R 4 ' respectively with Z in chemical formula 4 1 , R 1 , R 2 , R 3 and R 4 Same. 1 '、R 1 '、R2 '、R 3 ' and R 4 ' can be Z as chemical formula 4 herein 1 , R 1 , R 2 , R 3 and R 4 The substituents are described with reference to specific examples.

[0107] In another example, in Chemical Formula 4, when the hydroxyl group of the polyol having 2 to 6 hydroxyl groups is replaced by Z 1 and Z 2 When replacing, L 1 It can be a divalent to hexavalent organic group in which hydroxyl groups have been removed from a polyol. In one example, a glycerol having three hydroxyl groups has been removed from a The trivalent organic group from which the hydroxyl group is removed is represented by

[0108] In chemical formula 4, L 1 It may be, for example: a divalent organic group in which a hydroxyl group has been removed from a diol such as ethylene glycol, propylene glycol or butanediol; a trivalent organic group in which a hydroxyl group has been removed from a triol such as glycerol or trimethylolpropane; a tetravalent organic group in which a hydroxyl group has been removed from a tetraol such as pentaerythritol or ditrimethylolpropane; a pentavalent organic group in which a hydroxyl group has been removed from a pentaol such as 6-methylheptanepentaol; or a hexavalent organic group in which a hydroxyl group has been removed from a hexaol such as dipentaerythritol.

[0109] In chemical formula 4, when L 1 When L is a single bond or a divalent organic group, n and m are each 1. 1 is a trivalent to hexavalent organic group, n may be greater than m. In one example, n may be an integer of 1 to 3, and m may be an integer of 1.

[0110] In one example, L 1 It may be a trivalent organic group in which a hydroxyl group has been removed from glycerol which is a triol. In addition, n may be 2, and m may be 1. In this case, the fluorinated compound represented by Chemical Formula 4 may be represented by the following Chemical Formula 4-2.

[0111] [Chemical formula 4-2]

[0112]

[0113] Among them, in chemical formula 4-2,

[0114] Z 1 ”、Z 2 ”、R 1 ”、R 2 ”、R3 ” and R 4 ” respectively with Z in chemical formula 4 1 , Z 2 , R 1 , R 2 , R 3 and R 4 Same. 1 ”、Z 2 ”、R 1 ”、R 2 ”、R 3 ” and R 4 " can be Z as chemical formula 4 herein 1 , Z 2 , R 1 , R 2 , R 3 and R 4 The substituents are described with reference to specific examples.

[0115] In chemical formula 4, R 2 To R 4 At least one of the fluorine-containing substituents is a fluorine-containing substituent. The fluorine-containing substituent may be an alkyl group having 1 to 20 carbon atoms substituted with 2 or more fluorines, a cycloalkyl group having 3 to 30 carbon atoms substituted with 2 or more fluorines, or an aryl group having 6 to 30 carbon atoms substituted with 2 or more fluorines. Specifically, the fluorine-containing substituent may be a straight-chain alkyl group having 1 to 20 carbon atoms substituted with 2 or more fluorines. More specifically, the fluorine-containing substituent may be -(CH2) a (CF2) b CHF2 or -(CH2) a (CF2) b CF3. wherein a is an integer from 0 to 3, an integer from 0 to 2, or an integer from 1, and b may be an integer from 0 to 19, an integer from 0 to 15, an integer from 0 to 12, an integer from 0 to 11, an integer from 0 to 10, or an integer from 0 to 9.

[0116] When R in Formula 4 2 and R 3 When it is not a fluorine-containing substituent, R 2 and R 3 Each may independently be hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a heterocycloalkyl group having 4 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or may be a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-.

[0117] Specifically, when R in Chemical Formula 4 2 and R 3 When it is not a fluorine-containing substituent, R 2 and R 3 may be each independently hydrogen, a linear alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a heterocycloalkyl group having 4 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, or -(R 5 -O) p -R 6 . In -(R 5 -O) p -R 6 In, R 5 is an alkylene group having 1 to 6 carbon atoms, R 6 is an alkyl group having 1 to 6 carbon atoms, and p may be an integer of 1 to 12.

[0118] More specifically, when R in Chemical Formula 4 2 and R 3 When it is not a fluorine-containing substituent, R 2 and R 3 are each independently hydrogen, methyl, ethyl, propyl, butyl, cyclohexyl, tetrahydropyranyl, phenyl, or -(R 5 -O) p -R 6 Among them, R 5 It may be ethylene, n-propylene, or n-butylene, especially ethylene. 6 It can be methyl, ethyl, n-propyl, or n-butyl, especially methyl. p can be, for example, an integer of 1 to 12, an integer of 1 to 10, an integer of 1 to 8, an integer of 1 to 6, an integer of 1 to 5, an integer of 1 to 4, or an integer of 1 to 3.

[0119] When R in Formula 4 4 When it is not a fluorine-containing substituent, R 4 It may be an alkyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or may be a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-.

[0120] Specifically, when R in Chemical Formula 4 4 When it is not a fluorine-containing substituent, R 4 It may be a straight-chain alkyl group having 2 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, or -(R 5 -O)p -R 6 . In -(R 5 -O) p -R 6 In, R 5 is an alkylene group having 1 to 6 carbon atoms, R 6 is an alkyl group having 1 to 6 carbon atoms, and p may be an integer of 1 to 12.

[0121] More specifically, when R in Chemical Formula 4 4 When it is not a fluorine-containing substituent, R 4 Can be -(R 5 -O) p -R 6 Among them, R 5 It may be ethylene, n-propylene, or n-butylene, especially ethylene. 6 It can be methyl, ethyl, n-propyl, or n-butyl, especially methyl. p can be, for example, an integer of 1 to 12, an integer of 1 to 10, an integer of 1 to 8, an integer of 1 to 6, an integer of 1 to 5, an integer of 1 to 4, or an integer of 1 to 3.

[0122] The fluorinated compound represented by Chemical Formula 4 may include a fluorinated compound represented by Chemical Formula 4-1, a fluorinated compound represented by Chemical Formula 4-2, or a mixture thereof. Specifically, the fluorinated compound represented by Chemical Formula 4 may include at least one fluorinated compound selected from the fluorinated compounds represented by the following Chemical Formulas 4-1-1 to 4-1-5 and the following Chemical Formulas 4-2-1 to 4-2-5.

[0123] [Chemical formula 4-1-1]

[0124]

[0125] Among them, in chemical formula 4-1-1,

[0126] R a1 is methyl or ethyl,

[0127] R b1 and R b2 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms,

[0128] R c1 is CF3 or CHF2,

[0129] Z a1 is -O- or -NH-,

[0130] p1 and p2 are each independently an integer from 0 to 3, and q1 is an integer from 0 to 9,

[0131] [Chemical formula 4-1-2]

[0132]

[0133] Among them, in chemical formula 4-1-2,

[0134] R a2 is methyl or ethyl,

[0135] R b3 and R b4 are each independently cyclohexyl, tetrahydropyranyl, or phenyl,

[0136] R c2 is CF3 or CHF2,

[0137] Z a2 is -O- or -NH-, and

[0138] q2 is an integer from 0 to 9,

[0139] [Chemical formula 4-1-3]

[0140]

[0141] Among them, in chemical formula 4-1-3,

[0142] R a3 is methyl or ethyl,

[0143] R b5 and R b6 Each independently is CF3 or CHF2,

[0144] R c3 is an alkyl group having 1 to 4 carbon atoms,

[0145] Z a3 is -O- or -NH-,

[0146] p3 and p4 are each independently an integer from 0 to 9, and q3 is an integer from 0 to 3,

[0147] [Chemical formula 4-1-4]

[0148]

[0149] Among them, in chemical formula 4-1-4,

[0150] R a4 is methyl or ethyl,

[0151] R b7 is CF3 or CHF2,

[0152] R c4 and R c5are each independently an alkyl group having 1 to 4 carbon atoms,

[0153] Z a4 is -O- or -NH-,

[0154] p5 is an integer from 0 to 9, and q4 and q5 are each independently an integer from 0 to 3,

[0155] [Chemical formula 4-1-5]

[0156]

[0157] Among them, in chemical formula 4-1-5,

[0158] R a5 is methyl or ethyl,

[0159] R b8 is CF3 or CHF2,

[0160] R b9 is cyclohexyl, tetrahydropyranyl, or phenyl,

[0161] R c6 is an alkyl group having 1 to 4 carbon atoms,

[0162] Z a5 is -O- or -NH-,

[0163] p6 is an integer from 0 to 9, and q6 is an integer from 0 to 3,

[0164] [Chemical formula 4-2-1]

[0165]

[0166] Among them, in chemical formula 4-2-1,

[0167] R a6 is methyl or ethyl,

[0168] R b10 and R b11 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms,

[0169] R c7 and R c8 Each independently is CF3 or CHF2,

[0170] Z a6 is -O- or -NH-,

[0171] p7 and p8 are each independently an integer from 0 to 3, and q7 and q8 are each independently an integer from 0 to 9,

[0172] [Chemical formula 4-2-2]

[0173]

[0174] Among them, in chemical formula 4-2-2,

[0175] R a7 is methyl or ethyl,

[0176] R b12 and R b13 Each independently is CF3 or CHF2,

[0177] R c9 and R c10 are each independently an alkyl group having 1 to 4 carbon atoms,

[0178] Z a7 is -O- or -NH-,

[0179] p9 and p10 are each independently an integer from 0 to 9, and q9 and q10 are each independently an integer from 0 to 3,

[0180] [Chemical formula 4-2-3]

[0181]

[0182] Among them, in chemical formula 4-2-3,

[0183] R a8 is methyl or ethyl,

[0184] R b14 and R b15 are each independently cyclohexyl, tetrahydropyranyl, or phenyl,

[0185] R c11 and R c12 Each independently is CF3 or CHF2,

[0186] Z a8 is -O- or -NH-, and

[0187] q11 and q12 are each independently an integer from 0 to 9,

[0188] [Chemical formula 4-2-4]

[0189]

[0190] Among them, in chemical formula 4-2-4,

[0191] R a9 is methyl or ethyl,

[0192] R b16is CF3 or CHF2,

[0193] R b17 is cyclohexyl, tetrahydropyranyl, or phenyl,

[0194] R c13 and R c14 are each independently an alkyl group having 1 to 4 carbon atoms,

[0195] Z a9 is -O- or -NH-,

[0196] p11 is an integer from 0 to 9, and q13 and q14 are each independently an integer from 0 to 3,

[0197] [Chemical formula 4-2-5]

[0198]

[0199] Among them, in chemical formula 4-2-5,

[0200] R a10 is methyl or ethyl,

[0201] R b18 is CF3 or CHF2,

[0202] R c15 To R c17 are each independently an alkyl group having 1 to 4 carbon atoms,

[0203] Z a10 is -O- or -NH-,

[0204] p12 is an integer of 0 to 9, and q15 to q17 are each independently an integer of 0 to 3.

[0205] Based on 100 parts by weight of the polymer matrix, the photopolymer layer can include the fluorinated compound in an amount of 20 to 200 parts by weight. Specifically, the lower limit of the content of the fluorinated compound can be, for example, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 35 parts by weight or more, 40 parts by weight or more, 45 parts by weight or more, 50 parts by weight or more, or 55 parts by weight or more, and its upper limit can be, for example, 200 parts by weight or less, 180 parts by weight or less, 150 parts by weight or less, 120 parts by weight or less, or 100 parts by weight or less. When the above range is met, it can show a large refractive index modulation value after recording due to the fluorinated compound having a sufficiently low refractive index, without deteriorating the compatibility with the components contained in the photopolymer composition, some fluorinated compounds flowing out to the surface of the photopolymer layer or deteriorating the haze, which is conducive to ensuring excellent optical recording characteristics.

[0206] The photopolymer layer may also contain additives such as defoamers.

[0207] The photopolymer layer may contain a silicone-based reactive additive as a defoamer. As a silicone-based reactive additive, commercial products such as Tego Rad 2500 may be used, for example.

[0208] The content of the additive (eg, defoaming agent) may be appropriately adjusted to a level that does not interfere with the function of the hologram recording medium.

[0209] The photopolymer layer may be formed of a photopolymer composition including a solvent.

[0210] The solvent may be an organic solvent, and examples thereof may be at least one organic solvent selected from ketones, alcohols, acetates, and ethers, but are not limited thereto. Specific examples of such organic solvents include at least one selected from the following: ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or isobutyl ketone; alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or tert-butanol; acetates such as ethyl acetate, isopropyl acetate, or polyethylene glycol monomethyl ether acetate; and ethers such as tetrahydrofuran or propylene glycol monomethyl ether.

[0211] The organic solvent may be added at a point in time when the respective components contained in the photopolymer composition are mixed, or it may be added after the respective components are added in a state of being dispersed or mixed in the organic solvent and then contained in the photopolymer composition.

[0212] Photopolymer composition can include solvent so that solid content concentration is 1 wt % to 90 wt %. Specifically, photopolymer composition can include solvent so that solid concentration is 20 wt % or more, 30 wt % or more, 50 wt % or more, or 60 wt % or more and 85 wt % or less, 80 wt % or less, 75 wt % or less, or 70 wt % or less. Within the scope, photopolymer composition shows suitable fluidity and can form a coating film without defects (such as stripes). Defects will not occur during drying and curing process, and a photopolymer layer showing desired physical properties and surface properties can be formed.

[0213] Since the hologram recording medium according to one embodiment of the present invention includes the above-described photopolymer layer, it can exhibit excellent reliability and high transparency even in a high temperature / high humidity environment.

[0214] Specifically, the refractive index change rate of the hologram recording medium according to one embodiment of the present invention calculated by the following Equation 4 may be 1.0% or less.

[0215] [Equation 4]

[0216] Refractive index change rate (%) = {|1-n1 / n0|}×100

[0217] Wherein, in Equation 4, n0 is the refractive index of the sample in which the hologram recording medium before recording was stored at a temperature of 20°C to 25°C and a relative humidity of 40% to 50% and then bleached with a white LED, and n1 is the refractive index of the sample in which the hologram recording medium before recording was stored at a temperature of 60°C and a relative humidity of 90% for 72 hours and then bleached with a white LED.

[0218] The refractive index change rate of 1.0% or less means that even when the hologram recording medium before recording is exposed to high temperature and high humidity conditions, it shows excellent stability, and the difference in refractive index before and after exposure to high temperature and high humidity conditions is as small as 1.0% or less. In particular, since the plasticizer contained in the hologram recording medium before recording is a fluid, it may migrate to the surface of the photopolymer layer, making it impossible to exhibit the optical recording characteristics originally expected. However, the hologram recording medium according to one embodiment of the present invention contains the fluorinated compound represented by Chemical Formula 4 as a plasticizer, whereby the refractive index change rate calculated by Equation 4 can be very small.

[0219] The upper limit of the refractive index change rate of the hologram recording medium may be, for example, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.25% or less, or 0.2% or less. In addition, its lower limit may be, for example, 0% or more.

[0220] On the other hand, since the hologram recording medium uses a mixture of a component having a low refractive index and a component having a high refractive index to record optical properties, it tends to have opaque properties due to their compatibility. However, by using a fluorinated compound having a specific structure with which they have excellent compatibility, the hologram recording medium can exhibit high transparency optical properties.

[0221] Specifically, the haze of the hologram recording medium according to one embodiment of the present invention can be 2% or less. The upper limit of the haze can be, for example, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, or 0.7% or less. The lower limit of the haze is not particularly limited and can be 0% or more. The haze can be measured by the method described in the test example described below.

[0222] A hologram recording medium according to an embodiment of the present invention has excellent refractive index modulation, diffraction efficiency, and driving reliability despite having a thin thickness of a photopolymer layer.

[0223] The thickness of the photopolymer layer may be, for example, in the range of 5.0 μm to 40.0 μm. Specifically, the lower limit of the thickness of the photopolymer layer may be, for example, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. In addition, the upper limit of the thickness may be, for example, 35 μm or less, 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, or 18 μm or less.

[0224] The hologram recording medium according to one embodiment of the present invention may further include a substrate on at least one surface of the photopolymer layer. The type of substrate is not particularly limited, and those known in the relevant technical field can be used. For example, a substrate such as glass, PET (polyethylene terephthalate), TAC (triacetyl cellulose), PC (polycarbonate) or COP (cycloolefin polymer) can be used.

[0225] A hologram recording medium according to an embodiment of the present invention may have a high diffraction efficiency. In one example, when a notch filter hologram is recorded, the hologram recording medium may have a diffraction efficiency of 70% or more. Wherein, 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 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, 89% or more, 90% or more, or 91% or more. In this way, a hologram recording medium according to an embodiment of the present invention may achieve excellent diffraction efficiency even if it includes a thin thickness of a photopolymer layer. The diffraction efficiency may be measured by the method described in the test example described below.

[0226] Even if the thickness of the photopolymer layer is as thin as 5 μm to 30 μm, the hologram recording medium according to one embodiment of the present invention can achieve a refractive index modulation value (Δn) of 0.020 or more, 0.025 or more, 0.026 or more, 0.027 or more, 0.028 or more, 0.029 or more, 0.030 or more, 0.031 or more, 0.032 or more, 0.033 or more, 0.034 or more, or 0.035 or more. The upper limit of the refractive index modulation value is not particularly limited, but can be, for example, 0.060 or less. The refractive index modulation value can be measured by the method described in the test example described below.

[0227] A hologram recording medium according to an embodiment of the present invention can exhibit excellent durability in a high temperature / high humidity environment not only before recording but also even after recording.

[0228] In one example, the peak change rate of the hologram recording medium according to one embodiment of the present invention calculated by the following Equation 3 may be 3% or less.

[0229] [Equation 3]

[0230] Peak change rate = {|1-A1 / A0|}×100

[0231] Wherein, in Equation 3, A0 is the wavelength of the lowest transmittance of the hologram recording medium for the wavelength range of 300 nm to 1,200 nm, and A1 is the wavelength of the lowest transmittance measured after exposing the hologram recording medium to a temperature of 60° C. and a relative humidity of 90% for 72 hours.

[0232] The peak change rate describes the degree of movement of the wavelength exhibiting the lowest transmittance before and after high temperature / high humidity conditions. In one example, if a holographic grating (e.g., a reflection hologram) is recorded to reflect light of a specific wavelength of 680 nm, the transmittance at 680 nm has a minimum value. In addition, if the transmittance is measured again after exposure to high temperature / high humidity conditions, the minimum transmittance may occur at 675 nm. In such a case, according to the above equation 1, it can be considered to have a peak change rate of less than 1%. In this way, depending on the conditions under which the holographic grating is driven or stored, when the pitch of the diffraction grating is reduced (i.e., the diffraction grating shrinks), a peak change occurs in which the wavelength of the minimum transmittance moves to a shorter wavelength. Conversely, when the pitch of the holographic diffraction grating is increased (the diffraction grating expands), a peak change may occur in which the wavelength of the minimum transmittance moves to the longer wavelength side. The extent of this peak change depends on the reliability of the diffraction grating.

[0233] That is, a peak change rate value of 3% or less means that even when exposed to harsh conditions such as high temperature / high humidity, the deformation (contraction or expansion) of the diffraction grating can be suppressed as if its peak change rate is 3% or less. Such a hologram recording medium can provide good color reproducibility and image clarity even when exposed to harsh conditions.

[0234] The peak change rate of the hologram recording medium according to one embodiment of the present invention 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, or 1.1% or less. The lower limit of the peak change rate is not particularly limited and may be 0% or more.

[0235] Regarding the diffraction grating structure, the hologram recording medium may have a notch filter structure. A hologram recording medium according to an embodiment of the present invention having a notch filter structure may mean that the diffraction grating is non-tilted (substantially 0°) relative to the substrate surface, for example, as if the diffraction grating is parallel to the substrate surface. Such a hologram recording medium may have a structure in which two layers (e.g., a high refractive index layer and a low refractive index layer) with different refractive indices are repeated alternately. In addition, the two repeated layers may have predetermined thicknesses that are the same or different from each other, respectively. Such a non-tilted diffraction grating recording may be prepared in a manner that the incident angle of the incident object light and the incident angle of the reference light are equal based on the normal line. In the non-tilted structure, the degree of deformation (e.g., contraction or expansion) under high temperature / high humidity conditions is more clearly confirmed than in the tilted structure, and it is less affected by the contraction and expansion of the substrate.

[0236] The use of the hologram recording medium according to one embodiment of the present invention is not particularly limited. As a non-limiting example, the hologram recording medium can be used in applications that are likely to be exposed to high temperature / high humidity environments, specifically smart devices, such as mobile devices, parts of wearable displays, or automotive parts (such as head-up displays).

[0237] On the other hand, a hologram recording medium according to an embodiment of the present invention can be prepared by the step of applying a photopolymerizable composition to form a photopolymer layer, and can be prepared into a form in which optical information is recorded by the following steps: a step of irradiating a predetermined area of ​​the photopolymer layer thus prepared with coherent laser light and selectively polymerizing photoreactive monomers contained in the photopolymer layer to record optical information.

[0238] In the step of forming the photopolymer layer, a photopolymer composition including the above structure may be first prepared. When preparing the photopolymer composition, in order to mix the components, a known mixer, a stirrer, a mixer, etc. may be used without particular limitation. In addition, such a mixing process may be performed at a temperature ranging from 0°C to 100°C, a temperature ranging from 10°C to 80°C, or a temperature ranging from 20°C to 60°C.

[0239] In the step of forming the photopolymer layer, the prepared photopolymer composition may be applied to form a coating film formed of the photopolymer composition. The coating film may be dried naturally at room temperature or at a temperature in the range of 30° C. to 80° C. This process may cause a hydrosilylation reaction between the hydroxyl group of the (meth) acrylic polyol remaining unreacted and the silane functional group of the siloxane-based polymer.

[0240] In the photopolymer layer prepared by the step of forming the photopolymer layer, the fluorinated compound, the photoreactive monomer and the photoinitiator system, and additives added as needed may be uniformly dispersed in a cross-linked polymer matrix.

[0241] Subsequently, in the step of recording optical information, if coherent laser light is irradiated onto the photopolymer layer, polymerization of the photoreactive monomer occurs in the region where constructive interference occurs to form a photopolymer, and polymerization of the photoreactive monomer does not occur or is suppressed in the region where destructive interference occurs, so that the photoreactive monomer exists. In addition, when the unreacted photoreactive monomer causes refractive index modulation while diffusing toward the photopolymer side where the concentration of the photoreactive monomer is lower, a diffraction grating is generated by the refractive index modulation. Thus, a hologram (i.e., optical information) is recorded on the photopolymer layer having the diffraction grating.

[0242] The hologram recording medium according to one embodiment of the present invention can be provided in a state where the reaction of the photoreactive monomer is terminated and the color of the photosensitizing dye is removed by a photobleaching step (which can be performed after the step of recording the optical information) of irradiating light onto the entire photopolymer layer on which the optical information is recorded.

[0243] In one example, in the photobleaching step, ultraviolet light (UVA) in the range of 320 nm to 400 nm is irradiated to terminate the reaction of the photoreactive monomer and remove the color of the photosensitizing dye.

[0244] On the other hand, according to another embodiment of the present invention, a hologram recording medium is provided, which includes a photopolymer layer, wherein the photopolymer layer contains: a polymer matrix or a precursor thereof formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorinated compound represented by the following Chemical Formula 4.

[0245] [Chemical formula 4]

[0246]

[0247] Among them, in chemical formula 4,

[0248] Z 1 is -O- or -NH-,

[0249] Z 2 is a single bond, -O-, or -NH-,

[0250] L 1 is a single bond or a divalent to hexavalent organic group in which a hydroxyl group has been removed from a polyol having 2 to 6 hydroxyl groups,

[0251] n and m are each independently an integer from 1 to 5, wherein the sum of n and m is from 2 to 6,

[0252] R 1 is methyl or ethyl, and

[0253] R 2 To R 4 At least one of the fluorine-containing substituents is an alkyl group having 1 to 20 carbon atoms substituted by 2 or more fluorine groups, a cycloalkyl group having 3 to 30 carbon atoms substituted by 2 or more fluorine groups, or an aryl group having 6 to 30 carbon atoms substituted by 2 or more fluorine groups,

[0254] When R 2 and R 3 When it is not a fluorine-containing substituent, R 2 and R 3 each independently represents hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a heterocycloalkyl group having 4 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-, and

[0255] When R 4 When it is not a fluorine-containing substituent, R 4 It is an alkyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-.

[0256] A hologram recording medium according to another embodiment of the present invention contains a fluorinated compound having a specific structure as a plasticizer, so that it not only has improved optical recording characteristics but also can exhibit high reliability and high transparency optical characteristics even in a high temperature / high humidity environment.

[0257] For example, a hologram recording medium according to another embodiment can exhibit a certain degree of high reliability even in a high temperature / high humidity environment, so that the refractive index change rate calculated by Equation 4 has a low value of 1.0% or less, and it can exhibit high transparency with a haze of 2% or less, but is not limited to this.

[0258] For the polymer matrix or its precursor, the photoreactive monomer and the photoinitiator system or the photopolymer obtained therefrom, and the fluorinated compound represented by Chemical Formula 4 contained in the hologram recording medium according to another embodiment of the present invention, the same compounds as those contained in the hologram recording medium according to one embodiment of the present invention can be used. The polymer matrix or its precursor, the photoreactive monomer and the photoinitiator system or the photopolymer obtained therefrom, and the fluorinated compound represented by Chemical Formula 4 have been described in detail above, so their detailed description is omitted here.

[0259] On the other hand, according to still another embodiment of the present invention, there is provided an optical element including a hologram recording medium.

[0260] Specific examples of optical elements may include smart devices such as mobile devices, components of wearable displays, vehicle products (such as head-up displays), holographic fingerprint recognition systems, optical lenses, reflectors, deflection mirrors, filters, diffuser screens, diffraction elements, light guides, waveguides, holographic optical elements with projection screen and / or mask functions, media for optical storage systems and light diffuser plates, optical wavelength multiplexers, reflective and transmissive color filters, etc.

[0261] An example of an optical element including a hologram recording medium may include a hologram display device. The hologram display device includes a light source unit, an input unit, an optical system, and a display unit.

[0262] Specifically, the light source unit is a portion that irradiates a laser beam for providing, recording, and reproducing three-dimensional image information of an object in the input unit and the display unit.

[0263] The input unit is a part that pre-inputs three-dimensional image information of the object to be recorded on the display unit, specifically, the three-dimensional information of the object such as the intensity and phase of light in each space can be input into the electrically addressed liquid crystal SLM, where the input light beam can be used.

[0264] The optical system may include a reflector, a polarizer, a beam splitter, a beam gate, a lens, etc. The optical system may be allocated into an input beam for sending a laser beam emitted from a light source unit to an input unit, a recording beam for sending a laser beam to a display unit, a reference beam, an erasing beam, a reading beam, etc.

[0265] The display unit can receive the three-dimensional image information of the object from the input unit, record it on the hologram plate including the optically addressed SLM, and reproduce the three-dimensional image of the object. At this time, the three-dimensional image information of the object can be recorded by the interference of the input light beam and the reference light beam. The three-dimensional image information of the object recorded on the hologram plate can be reproduced as a three-dimensional image through the diffraction pattern generated by the read light beam. The erase light beam can be used to quickly remove the formed diffraction pattern. On the other hand, the hologram plate can be moved between the position of the input three-dimensional image and the position of the reproduced three-dimensional image.

[0266] Beneficial Effects

[0267] A hologram recording medium according to an embodiment of the present invention not only has excellent optical recording characteristics but can also exhibit transparent optical characteristics and can exhibit excellent reliability even in a high-temperature and high-humidity environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0268] Figure 1 The recording device setup for hologram recording is schematically shown. Specifically, Figure 1 The following process is schematically shown: laser light of a predetermined wavelength is radiated from a light source 10 and is irradiated onto a PP (hologram recording medium) 80 located on one surface of a reflector 70 via reflectors 20 and 20', an aperture 30, a spatial filter 40, an aperture 30', a collimating lens 50 and a PBS (Polarized Beam Splitter) 60. DETAILED DESCRIPTION

[0269] Hereinafter, the action and effect of the present invention will be described in more detail with reference to specific embodiments of the present invention. However, these embodiments are presented for illustrative purposes only, and the scope of the present invention is not limited thereby in any way.

[0270] In the following Preparation Examples, Examples, and Comparative Examples, unless otherwise specified, the content of raw materials and the like means the content based on the solid content.

[0271] Preparation Example 1: Preparation of (meth)acrylic polyol

[0272] 132g butyl acrylate, 420g ethyl acrylate and 48g hydroxybutyl acrylate are added to a 2L jacket reactor and diluted with 1200g ethyl acetate. The reaction temperature is set to 60°C to 70°C, and the mixture is stirred for about 30 minutes to 1 hour. 0.42g n-dodecyl mercaptan (n-DDM) is further added and stirred for about 30 minutes. Then, 0.24g AIBN is added as a polymerization initiator, and polymerization is carried out at the reaction temperature for 4 hours or more, and maintained until the residual acrylate content becomes less than 1%. Thus, a copolymer based on (meth) acrylate in which hydroxyl groups are located in the side chains (weight average molecular weight of about 300,000, OH equivalent of about 1802g / equivalent) is prepared.

[0273] Example 1: Preparation of photopolymer composition and hologram recording medium

[0274] (1) Preparation of photopolymer composition

[0275] First, 1.27 g of poly(methylhydrogensiloxane) (Sigma-Aldrich, number average molecular weight: about 390, Si—H equivalent: about 103 g / equivalent) as a siloxane-based polymer and 11.12 g of the (meth)acrylic polyol prepared in Preparation Example 1 were mixed (SiH / OH molar ratio = 2.0).

[0276] Then, 20 g of HR 6042 (Miwon Specialty Chemical, refractive index 1.60) as a photoreactive monomer, 0.08 g of photosensitizing dye H-Nu 640 (Spectra Group), 0.3 g of borate V as a co-initiator, 0.05 g of H-Nu 254 (Spectra), 10 g of a fluorinated compound represented by the following chemical formula a as a plasticizer, and 26 g of methyl isobutyl ketone (MIBK) as a solvent were added, and the mixture was stirred for about 30 minutes with a paste mixer while shielding from light. After that, a photopolymer composition was prepared by adding a Karstedt (Pt-based) catalyst for matrix crosslinking.

[0277] [Chemical formula a]

[0278]

[0279] (2) Preparation of hologram recording media

[0280] The photopolymer composition was coated on a 60 μm thick TAC substrate to a predetermined thickness using a Mayer rod, and dried at 80° C. for 10 minutes. The thickness of the photopolymer layer after drying was about 15 μm.

[0281] Use with Figure 1The diffraction grating is recorded with the same settings as in the embodiment. Specifically, when the prepared photopolymer layer is laminated on a reflector and then irradiated with a laser, a notch filter hologram having a periodic refractive index modulation in the thickness direction by interference between the incident light L and the light L' reflected from the reflector can be recorded. In this embodiment, the notch filter hologram is recorded at an incident angle of 0° (degrees). Notch filters and Bragg reflectors are optical devices that reflect only light of a specific wavelength, and have a structure in which two layers with different refractive indices are periodically and repeatedly stacked at a certain thickness.

[0282] Examples 2 to 11 and Comparative Examples 1 to 4: Preparation of Photopolymer Compositions and Hologram Recording Media

[0283] A photopolymer composition and a hologram recording medium were prepared in the same manner as in Example 1, except that the components and contents of the photopolymer composition as shown in Table 1 below were different.

[0284] [Table 1]

[0285]

[0286] [Chemical formula b]

[0287]

[0288] [Chemical formula c]

[0289]

[0290] [Chemical formula d]

[0291]

[0292] [Chemical formula e]

[0293]

[0294] [Chemical formula f]

[0295]

[0296] [Chemical formula g]

[0297]

[0298] [Chemical formula h]

[0299]

[0300] [Chemical formula i]

[0301]

[0302] [Chemical formula j]

[0303]

[0304] [Chemical formula k]

[0305]

[0306] Test example: Performance evaluation of hologram recording media

[0307] (1) Diffraction efficiency

[0308] The diffraction efficiency (η) is determined by the following Equation 1.

[0309] [Equation 1]

[0310] η(%)={P D / (P D +P T )}×100

[0311] Where, in equation 1, η is the diffraction efficiency, P D is the output of the diffracted beam of the sample after recording (mW / cm 2 ), and P T is the output of the transmitted light beam of the sample after recording (mW / cm 2 ).

[0312] (2) Refractive index modulation value (Δn)

[0313] The refractive index modulation value (Δn) is determined by the following Equation 2 and the Bragg equation.

[0314] [Equation 2]

[0315]

[0316] [Bragg equation]

[0317]

[0318] Wherein, in the equation, η is the reflection diffraction efficiency (DE), d is the thickness of the photopolymer layer, λ is the wavelength of the incident light for recording (660nm or 532nm), θ is the incident angle of the incident light for recording, φ is the tilt angle of the grating, Δn is the refractive index modulation value, n is the refractive index of the photopolymer, and Λ means the diffraction grating period. In the above embodiments and comparative examples, since the notch filter method is used to record the hologram, both θ (incident angle) and φ (tilt angle of the grating) are 0°.

[0319] (3) Haze

[0320] The haze was measured using a haze meter (Murakami Color Research Laboratory, HM-150) in accordance with JIS K 7136. The measurement light was made incident on the substrate-side surface of the hologram recording medium.

[0321] (4) Peak change rate

[0322] In order to evaluate the reliability of a hologram recording medium having a diffraction grating recorded in a high temperature / high humidity environment, the degree of shift of the wavelength showing the maximum reflectivity before and after exposing the sample having the diffraction grating recorded to the high temperature / high humidity condition was determined.

[0323] First, the specific wavelength (or wavelength band) (A0) at which the sample with the highest reflectivity (i.e., lowest transmittance) of the diffraction grating is recorded is analyzed (analyzed at room temperature and not under high humidity conditions). The analysis is performed using a UV-Vis spectrometer, and the analysis wavelength range is 300nm to 1,200nm.

[0324] Subsequently, the same sample was stored at a temperature of 60°C and a relative humidity of 90% for 72 hours, and the wavelength (or wavelength band) (A1) at which the reflectance was the largest (transmittance was the smallest) was recorded in a similar manner. The peak change rate was measured according to the following equation 3, which is the degree of movement of the wavelength with the lowest transmittance before and after the evaluation. At this time, it is assumed that sample deformation (such as contraction or expansion) does not affect the surface pitch and occurs only in the direction perpendicular to the sample surface.

[0325] [Equation 3]

[0326] Peak change rate = {|1-A1 / A0|}×100

[0327] (5) Refractive index change rate

[0328] In order to evaluate the stability of the hologram recording medium in a high temperature / high humidity environment before recording the diffraction grating, the extent of the refractive index change before and after exposing the sample to the high temperature / high humidity condition before recording the diffraction grating was determined.

[0329] Specifically, the hologram recording medium before recording prepared in the examples and comparative examples was stored under constant temperature (20° C. to 25° C.) and constant humidity (40% to 50% relative humidity) conditions, and then bleached with a white LED before recording. A sample that was not exposed to a high temperature / high humidity environment was prepared. Then, the refractive index n0 of the sample was measured using a prism coupler (SPA-3DR, SAIRONTECHNOLOGY).

[0330] On the other hand, the hologram recording medium before recording prepared in the examples and comparative examples was stored at a temperature of 60°C and a relative humidity of 90% for 72 hours, bleached with a white LED, and a sample exposed to a high temperature / high humidity environment before recording was prepared. Then, the refractive index n1 of the sample was measured using a prism coupler.

[0331] The refractive index change rate is calculated by substituting n0 and n1 into the following Equation 4.

[0332] [Equation 4]

[0333] Refractive index change rate (%) = {|1-n1 / n0|}×100

[0334] Wherein, in Equation 4, n0 is the refractive index of the sample in which the hologram recording medium before recording was stored at a temperature of 20°C to 25°C and a relative humidity of 40% to 50% and then bleached with a white LED, and n1 is the refractive index of the sample in which the hologram recording medium before recording was stored at a temperature of 60°C and a relative humidity of 90% for 72 hours and then bleached with a white LED.

[0335] [Table 2]

[0336]

[0337] Referring to Table 2, it was determined that the hologram recording media prepared in Examples 1 to 11 not only exhibited excellent diffraction efficiency, refractive index modulation value, and low haze, but also exhibited excellent reliability before and after recording even after exposure to a high temperature / high humidity environment. In contrast, the hologram recording media prepared in Comparative Examples 2 to 4 were inferior in optical recording characteristics, haze, and reliability in a high temperature / high humidity environment. In addition, the hologram recording medium prepared in Comparative Example 1 had excellent optical recording characteristics, but had high haze and exhibited poor reliability in a high temperature / high humidity environment before and after recording.

[0338] Therefore, it was confirmed that since the hologram recording medium according to one embodiment of the present invention contains a fluorinated compound having a specific structure, it has excellent optical recording characteristics, has excellent reliability even in a high temperature / high humidity environment, and exhibits high transparency.

Claims

1. A hologram recording medium comprising a photopolymer layer, the photopolymer layer comprising: a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic polyol or a precursor thereof; a photoreactive monomer and a photoinitiator system or a photopolymer obtained therefrom; and a fluorinated compound, wherein the refractive index change rate calculated by the following equation 4 is 1.0% or less, and Where the haze is 2% or less: [Equation 4] Refractive index change rate (%) = {|1-n1 / n0|}×100 in, In Equation 4, n0 is the refractive index of a sample in which the hologram recording medium before recording was stored at a temperature of 20°C to 25°C and a relative humidity of 40% to 50% and then bleached with a white LED, and n1 is the refractive index of a sample in which the hologram recording medium before recording was stored at a temperature of 60°C and a relative humidity of 90% for 72 hours and then bleached with a white LED.

2. The hologram recording medium according to claim 1, wherein the siloxane-based polymer comprises a repeating unit represented by the following Chemical Formula 1 and a terminal group represented by the following Chemical Formula 2: [Chemical formula 1] in, In Chemical Formula 1, Plural R 11 and R 12 are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and k is an integer from 1 to 10,000, [Chemical formula 2] Wherein, in Chemical Formula 2, Plural R 13 To R 15 are the same as or different from each other and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and R is selected from at least one repeating unit among the repeating units represented by Chemical Formula 1 and any one terminal group among the terminal groups represented by Chemical Formula 2. 11 To R 15 At least one of them is hydrogen. 3 . The hologram recording medium according to claim 1 , wherein the (meth)acrylic polyol is a polymer in which a hydroxyl group is bonded to a main chain or a side chain of a (meth)acrylate-based polymer.

4. The hologram recording medium according to claim 1, wherein the photoreactive monomer comprises: At least one monofunctional monomer selected from 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 biphenyl methyl (meth)acrylate; selected from bisphenol A (ethylene oxide) 2～10 At least one multifunctional monomer selected from the group consisting of di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisfluorene di(meth)acrylate, modified bisphenol fluorene di(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, phenol novolac epoxy (meth)acrylate and cresol novolac epoxy (meth)acrylate; or a mixture of two or more thereof.

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

6. The hologram recording medium according to claim 5, wherein the coinitiator comprises a borate anion represented by the following Chemical Formula 3: [Chemical formula 3] BX 1 X 2 X 3 X 4 in, In chemical formula 3, X 1 To X 4 are each independently a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, provided that X 1 To X 4 At least one of the groups is not an aryl group.

7. The hologram recording medium according to claim 1, wherein the fluorinated compound comprises a fluorinated compound represented by the following Chemical Formula 4: [Chemical formula 4] in, In chemical formula 4, Z 1 is -O- or -NH-, Z 2 is a single bond, -O-, or -NH-, L 1 is a single bond or a divalent to hexavalent organic group in which a hydroxyl group has been removed from a polyol having 2 to 6 hydroxyl groups, n and m are each independently an integer from 1 to 5, wherein the sum of n and m is from 2 to 6, R 1 is methyl or ethyl, and R 2 To R 4 At least one of the fluorine-containing substituents is an alkyl group having 1 to 20 carbon atoms substituted by 2 or more fluorine groups, a cycloalkyl group having 3 to 30 carbon atoms substituted by 2 or more fluorine groups, or an aryl group having 6 to 30 carbon atoms substituted by 2 or more fluorine groups, When R 2 and R 3 When it is not a fluorine-containing substituent, R 2 and R 3 each independently represents hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a heterocycloalkyl group having 4 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-, and When R 4 When it is not a fluorine-containing substituent, R 4 It is an alkyl group having 2 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a cycloalkylalkyl group having 7 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 4 to 30 carbon atoms, or an arylalkyl group having 7 to 40 carbon atoms, or a substituent in which at least one -CH2- of the above substituents is replaced by -O-, -S- or -NH-.

8. The hologram recording medium according to claim 7, wherein L in Chemical Formula 4 1 is a single bond; or a trivalent organic group from which a hydroxyl group has been removed from glycerol which is a triol. 9 . The hologram recording medium according to claim 7 , wherein the fluorine-containing substituent is a linear alkyl group having 1 to 20 carbon atoms substituted with 2 or more fluorines.

10. The hologram recording medium according to claim 7, wherein the fluorine-containing substituent is -(CH2) a (CF2) b CHF2 or -(CH2) a (CF2) b CF3, wherein a is an integer from 0 to 3, and b is an integer from 0 to 19.

11. The hologram recording medium according to claim 7, wherein when R in Chemical Formula 4 2 and R 3 When it is not a fluorine-containing substituent, R 2 and R 3 are each independently hydrogen, a straight chain alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a heterocycloalkyl group having 4 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, or -(R 5 -O) p -R 6 , where R 5 is an alkylene group having 1 to 6 carbon atoms, R 6 is an alkyl group having 1 to 6 carbon atoms, and p is an integer of 1 to 12.

12. The hologram recording medium according to claim 7, wherein when R in Chemical Formula 4 4 When it is not a fluorine-containing substituent, R 4 is a straight-chain alkyl group having 2 to 6 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, or -(R 5 -O) p -R 6 , where R 5 is an alkylene group having 1 to 6 carbon atoms, R 6 is an alkyl group having 1 to 6 carbon atoms, and p is an integer of 1 to 12.

13. The hologram recording medium according to claim 7, wherein the fluorinated compound represented by Chemical Formula 4 includes at least one fluorinated compound selected from the group consisting of fluorinated compounds represented by the following Chemical Formulas 4-1-1 to 4-1-5 and the following Chemical Formulas 4-2-1 to 4-2-5: [Chemical formula 4-1-1] in, In chemical formula 4-1-1, R a1 is methyl or ethyl, R b1 and R b2 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, R c1 is CF3 or CHF2, Z a1 is -O- or -NH-, p1 and p2 are each independently an integer from 0 to 3, and q1 is an integer from 0 to 9, [Chemical formula 4-1-2] Among them, in chemical formula 4-1-2, R a2 is methyl or ethyl, R b3 and R b4 are each independently cyclohexyl, tetrahydropyranyl, or phenyl, R c2 is CF3 or CHF2, Z a2 is -O- or -NH-, and q2 is an integer from 0 to 9, [Chemical formula 4-1-3] Among them, in chemical formula 4-1-3, R a3 is methyl or ethyl, R b5 and R b6 Each independently is CF3 or CHF2, R c3 is an alkyl group having 1 to 4 carbon atoms, Z a3 is -O- or -NH-, p3 and p4 are each independently an integer from 0 to 9, and q3 is an integer from 0 to 3, [Chemical formula 4-1-4] Among them, in chemical formula 4-1-4, R a4 is methyl or ethyl, R b7 is CF3 or CHF2, R c4 and R c5 are each independently an alkyl group having 1 to 4 carbon atoms, Z a4 is -O- or -NH-, p5 is an integer from 0 to 9, and q4 and q5 are each independently an integer from 0 to 3, [Chemical formula 4-1-5] Among them, in chemical formula 4-1-5, R a5 is methyl or ethyl, R b8 is CF3 or CHF2, R b9 is cyclohexyl, tetrahydropyranyl, or phenyl, R c6 is an alkyl group having 1 to 4 carbon atoms, Z a5 is -O- or -NH-, p6 is an integer from 0 to 9, and q6 is an integer from 0 to 3, [Chemical formula 4-2-1] Among them, in chemical formula 4-2-1, R a6 is methyl or ethyl, R b10 and R b11 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, R c7 and R c8 Each independently is CF3 or CHF2, Z a6 is -O- or -NH-, p7 and p8 are each independently an integer from 0 to 3, and q7 and q8 are each independently an integer from 0 to 9, [Chemical formula 4-2-2] Among them, in chemical formula 4-2-2, R a7 is methyl or ethyl, R b12 and R b13 Each independently is CF3 or CHF2, R c9 and R c10 are each independently an alkyl group having 1 to 4 carbon atoms, Z a7 is -O- or -NH-, p9 and p10 are each independently an integer from 0 to 9, and q9 and q10 are each independently an integer from 0 to 3, [Chemical formula 4-2-3] Among them, in chemical formula 4-2-3, R a8 is methyl or ethyl, R b14 and R b15 are each independently cyclohexyl, tetrahydropyranyl, or phenyl, R c11 and R c12 Each independently is CF3 or CHF2, Z a8 is -O- or -NH-, and q11 and q12 are each independently an integer from 0 to 9, [Chemical formula 4-2-4] Among them, in chemical formula 4-2-4, R a9 is methyl or ethyl, R b16 is CF3 or CHF2, R b17 is cyclohexyl, tetrahydropyranyl, or phenyl, R c13 and R c14 are each independently an alkyl group having 1 to 4 carbon atoms, Z a9 is -O- or -NH-, p11 is an integer from 0 to 9, and q13 and q14 are each independently an integer from 0 to 3, [Chemical formula 4-2-5] Among them, in chemical formula 4-2-5, R a10 is methyl or ethyl, R b18 is CF3 or CHF2, R c15 To R c17 are each independently an alkyl group having 1 to 4 carbon atoms, Z a10 is -O- or -NH-, p12 is an integer from 0 to 9, and q15 to q17 are each independently an integer of 0 to 3. 14 . The hologram recording medium according to claim 1 , wherein the fluorinated compound is included in an amount of 20 parts by weight to 200 parts by weight based on 100 parts by weight of the polymer matrix.

15. The hologram recording medium according to claim 1, wherein when a notch filter hologram is recorded, a diffraction efficiency is 70% or more. 16 . The hologram recording medium according to claim 1 , wherein the photopolymer layer has a thickness of 5 μm to 30 μm and a refractive index modulation value of 0.020 or more.

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

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