Photopolymer film, composition for forming photopolymer film, hologram recording medium, and optical element

Abstract

The present invention relates to a photopolymer film including a base film and a recording layer, having a maximum reduction rate of a predetermined band area in a graph derived from the result of photo-thermal infrared spectroscopy (PTIR) in the thickness direction from one surface of the recording layer, a composition for forming such a photopolymer film, a hologram recording medium including the same, and an optical element.

Description

Technical Field

[0001] The present invention relates to a photopolymer film, a composition for forming such a photopolymer film, a hologram recording medium containing the photopolymer film, and an optical element.

Background Art

[0002] A hologram recording medium records information by changing the refractive index in a holographic recording layer within the medium during an exposure process, and reproduces the information by reading the change in the refractive index within the medium thus recorded.

[0003] When using a photopolymer (photosensitive resin), since an optical interference pattern can be easily stored as a hologram by photopolymerization of low-molecular monomers, it can be used in various fields such as holographic optical elements having functions of optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, diffraction members, light conductors, waveguides, projection screens and / or masks, media for optical memory systems, light diffusion plates, optical wavelength dividers, reflective and transmissive color filters, etc.

[0004] A photopolymer film can be manufactured by applying a composition containing a low-molecular monomer and a photoinitiator, etc. to a base film and then thermally curing it. The photopolymer film manufactured in such a way is composed of a base film and a recording layer where recording is performed. Laser interference light is irradiated onto such a recording layer to induce local photopolymerization of the monomer.

[0005] However, in the case of a photopolymer film manufactured in such a way, the adhesion between the base film and the recording layer is low, and the reliability may decrease due to the influence of the external environment. Therefore, many studies have been made to improve the adhesion, but the degree of improvement in physical properties by this is currently insufficient.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention provides a photopolymer film that exhibits excellent heat and heat-moisture reliability while showing improved adhesion between a base film and a recording layer, and has optimized recording efficiency.

[0007] The present invention also provides a composition for forming the photopolymer film.

[0008] Furthermore, the present invention provides a hologram recording medium and an optical element including the photopolymer film.

Means for Solving the Problems

[0009] In this specification, a graph derived from the results of photothermal infrared spectroscopy (PTIR) in the thickness direction from one surface of the recording layer facing the base film, including the base film and the recording layer, has the band area of the peak of the carbonyl group (C=O group) contained in the recording layer on the Y-axis, and the distance in the thickness direction from one surface of the recording layer facing the base film on the X-axis, and a photopolymer film satisfying the following formula 1 is provided.

[0010] Also, in this specification, a resin composition for forming a photopolymer film is provided, which includes a coating liquid containing a polymer matrix containing a siloxane-based polymer or a precursor thereof, a photoreactive monomer, and an erosive solvent, and the content of the erosive solvent is 25% by weight or more and 70% by weight or less based on 100% by weight of the coating liquid.

[0011] Furthermore, in this specification, a hologram recording medium including the photopolymer film is provided.

[0012] Also, in this specification, an optical element including the photopolymer film is provided.

[0013] Hereinafter, the photopolymer film according to the specific embodiments of the invention, the resin composition for forming the same, the hologram recording medium containing the same, and the optical element will be described in more detail.

[0014] As used herein, a hologram means a recording medium in which optical information is recorded in the entire visible range and the near ultraviolet range (300 - 800 nm) during the exposure process. For example, it includes all visual holograms such as in-line (Gabor) holograms, off-axis holograms, full-aperture transfer holograms, white light transmission holograms ("rainbow holograms"), Denisyuk holograms, off-axis reflection holograms, edge-literature holograms, or holographic stereograms.

[0015] As used herein, (meth)acrylate means both acrylate and methacrylate.

[0016] In addition, in this specification, the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) mean the molecular weight in terms of polystyrene (unit: Da (Dalton)) measured by gel permeation chromatography (GPC). In the process of measuring the weight-average molecular weight in terms of polystyrene measured by the GPC method, a commonly known analyzer, detectors such as a refractive index detector, and analytical columns can be used, and the usually applied temperature conditions, solvents, and flow rates can be applied. Specific examples of the measurement conditions include a temperature of 30 °C, a chloroform solvent, and a flow rate of 1 mL / min. When giving specific examples of the measurement conditions, using a column with a length of Polymer Laboratories PLgel MIX-B 300 mm, using Waters PL-GPC220 equipment, the evaluation temperature is 160 °C, using 1,2,4-trichlorobenzene as a solvent, the flow rate is 1 mL / min, the sample is prepared at a concentration of 10 mg / 10 mL, and then supplied in an amount of 200 μL. The values of Mw and Mn are respectively obtained using a calibration curve formed using polystyrene standards. Nine types of molecular weights of polystyrene standards, namely 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000, were used.

[0017] According to an embodiment of the invention, a photopolymer film including a substrate film and a recording layer can be provided, wherein a graph derived from the result of photothermal infrared spectroscopy (PTIR) in the thickness direction from one surface of the recording layer facing the substrate film has the band area of the carbonyl group (C=O group) contained in the recording layer on the Y-axis and the distance in the thickness direction from one surface of the recording layer facing the substrate film on the X-axis, and the graph satisfies the following formula 1.

[0018] [Formula 1] 0.010 μm -1≤Maximum reduction rate of band area≤0.095 μm -1

[0019] In the above formula 1, The maximum reduction rate of the band area is the absolute value of the minimum value of the y value in the graph obtained by first differentiating the above graph.

[0020] The inventors of the present invention include a base film and a recording layer, and the maximum reduction rate of the band area according to the above formula 1 is 0.010 μm -1 or more, 0.020 μm -1 or more, 0.030 μm -1 or more, 0.040 μm -1 or more, 0.050 μm -1 or more, 0.060 μm -1 or more, or 0.062 μm -1 or more and, 0.095 μm -1 or less, 0.090 μm -1 or less, 0.085 μm -1 or less, 0.082 μm -1 In the case of a photopolymer film of or less, it was confirmed that the adhesion between the base film and the recording layer was excellent and excellent heat and damp heat reliability was exhibited, and the present invention was completed.

[0021] The photothermal infrared spectroscopy (PTIR; Photothermal Infrared Spectroscopy) can be measured in the thickness direction of the recording layer with respect to one surface of the recording layer facing the base film. At this time, the measurement interval may be 0.3 to 5 μm, 0.5 to 2 μm, or 1 μm.

[0022] For example, when the measurement interval is 1 μm, one surface of the recording layer is used as a reference (0 μm), and first, photothermal infrared spectroscopy is performed. Second, photothermal infrared spectroscopy is performed at a position 1 μm in the thickness direction with respect to one surface of the recording layer. Third, photothermal infrared spectroscopy may be performed at a position 2 μm in the thickness direction with respect to one surface of the recording layer. Thereafter, the photothermal infrared spectroscopy may be sequentially performed at intervals of 1 μm in the thickness direction up to one surface of the optical film facing the recording layer.

[0023] In the graph derived by the above-mentioned photo-thermal infrared spectroscopic analysis, the X-axis is the distance in the thickness direction from one surface of the recording layer facing the base film. When the X value is 0 μm, it means one surface (the surface) of the recording layer facing the optical film. Also, the result values in the graph can appear according to the measurement interval. For example, when the measurement interval of the photo-thermal infrared spectroscopic analysis is 1 μm, the result values can appear at intervals of 1 μm on the X-axis in the graph.

[0024] Also, in the graph, the Y-axis is the band area of the peak of the carbonyl group (C=O group) contained in the recording layer, and the peak of the carbonyl group (C=O group) can appear at about 1720 - 1725 cm -1 -1.

[0025] For example, when photo-thermal infrared spectroscopic analysis is performed in the thickness direction on the recording layer, the value of the band area of the peak of the carbonyl group contained in the recording layer can appear as the Y value. For example, when the photo-reactive monomer contained in the recording layer contains an acrylate group, the band area of the peak of the carbonyl group (C=O group) of the acrylate group can appear as the value on the Y-axis. That is, the graph derived from the result of the photo-thermal infrared spectroscopic analysis is a graph in which the value of the band area of the peak of the carbonyl group (C=O group) contained in the recording layer, which is the Y value corresponding to the X value (the distance in the thickness direction from one surface of the recording layer facing the base film), appears.

[0026] On the other hand, FIG. 2 is a diagram schematically showing the movement of the peak of the carbonyl group (C=O group) as a result of photo-thermal infrared spectroscopic analysis in the thickness direction from one surface of the recording layer facing the base film. It can be confirmed that the movement occurs from the peak of the carbonyl group contained in the red recording layer to the peak of the carbonyl group contained in the blue base film. Also, an erosion layer is further included between the recording layer and the base film, and it can be confirmed that the movement appears schematically between the peaks of the red and blue carbonyl groups (C=O group) due to the formation in the erosion layer.

[0027] In addition, the graph derived from the results of the photo-thermal infrared spectroscopic analysis may be fitted with a Boltzmann sigmoid function according to the following mathematical formula 2.

[0028] [Number]

[0029] In the mathematical formula 2, A 1 : Initial value, the band area of the peak of the carbonyl group on one side of the recording layer facing the base film A 2 : Final value, the band area of the peak of the carbonyl group on one side of the recording layer close to the base film X 0 : The x value having the intermediate y value (Center), the x value at the point where the band area of the carbonyl group in the recording layer is (A 1 +A 2 ) / 2 dx: Time constant, the reduction rate from A 1 to A 2

[0030] After fitting the data derived from the results of the photo-thermal infrared spectroscopic analysis with a Boltzmann sigmoid function, in the graph obtained by differentiating the graph fitted with the Boltzmann sigmoid function once, the absolute value of the minimum value of the y value may be the maximum reduction rate of the band area. That is, the maximum reduction rate of the band area may be the absolute value of the minimum value of the slope in the graph of the photo-thermal infrared spectroscopic analysis or the graph obtained by fitting the graph of the photo-thermal infrared spectroscopic analysis with a Boltzmann sigmoid function.

[0031] The photopolymer film according to the above embodiment has a maximum reduction rate of the band area of 0.010 μm -1 or more and 0.012 μm-1 0.014 μm or more -1 0.020 μm or more -1 0.030 μm or more -1 0.040 μm or more -1 0.050 μm or more -1 0.060 μm or more -1 or 0.062 μm or more -1 0.095 μm or less -1 0.093 μm or less -1 0.091 μm or less -1 0.090 μm or less -1 0.085 μm or less -1 0.082 μm or less -1 It may be less. If the maximum reduction rate of the band area is excessively small, the erosion layer described later may be formed excessively thick, and the thickness of the recording layer to be substantially recorded may rather be thin, showing low recording efficiency. If the maximum reduction rate of the band area is excessively large, the erosion layer described later may not be formed, the adhesion between the base film and the recording layer may be low, and the heat resistance and moisture heat resistance reliability may decrease.

[0032] The photopolymer film according to the above embodiment may further include an erosion layer between the base film and the recording layer. For example, the erosion layer and the recording layer may be sequentially formed on the base film. Further, the erosion layer and the recording layer may be included as a coating layer, that is, the photopolymer film may include a coating layer including the erosion layer and the recording layer.

[0033] During the production of the photopolymer film, the composition of the coating solution may be adjusted to form an erosion layer on the base film. For example, the coating solution may include a polymer matrix containing a siloxane-based polymer or a precursor thereof, a photoreactive monomer, an erosive solvent, etc. When the coating solution is applied to the base film, the erosive solvent can dissolve at least a part of the base film and the coating solution can penetrate.

[0034] Thereafter, when a drying process for forming a coating layer is performed, the polymer matrix containing the siloxane-based polymer can be cured or crosslinked to form an erosion layer, and the erosion layer can contain a photoreactive monomer and / or a part of the substrate. Further, the erosion layer formed by the polymer matrix containing the siloxane-based polymer that has penetrated into the substrate film can be physically bonded to the substrate film.

[0035] Therefore, the erosion layer is formed by the erosive solvent contained in the coating solution dissolving a part of the substrate film so that the coating solution penetrates, and the polymer matrix contained in the thus-penetrated coating solution is cured or crosslinked. Thus, the erosion layer may contain a part of the components of the substrate film dissolved by the erosive solvent. Further, physical bonding may be performed between the polymer matrix and the substrate contained in the erosion layer by a drying process.

[0036] On the other hand, a recording layer may be formed on the erosion layer, and the recording layer can contain a polymer matrix containing a siloxane-based polymer, a photoreactive monomer, and the like.

[0037] As described above, by forming an erosion layer on the substrate film, the adhesion between the optical film and the recording layer can be greatly improved. By adjusting the degree of formation of the erosion layer, the reduction in the recording efficiency of the photopolymer film can be minimized while having excellent mechanical properties such as heat resistance and reliability under humid heat conditions. The presence or absence of the erosion layer or the thickness of the erosion layer can be confirmed using the above-described photo-thermal infrared spectroscopic analysis.

[0038] When manufacturing the photopolymer film, the composition of the coating solution may be adjusted to form an erosion layer on the base film. For example, the coating solution may include a polymer matrix containing a siloxane-based polymer or a precursor thereof, a photoreactive monomer, a solvent, etc. As a result, the recording layer may include a polymer matrix containing a siloxane-based polymer and a photoreactive monomer.

[0039] Also, the erosion layer can be formed by controlling the weight ratio of the photoreactive monomer to the polymer matrix containing the siloxane-based polymer. For example, when the weight ratio of the polymer matrix containing the photoreactive monomer and the siloxane-based polymer is 45:55 to 90:10, 45:55 to 85:15, 45:55 to 80:20, 45:55 to 75:25, 45:55 to 72:28, 48:52 to 72:28, an erosion layer may be formed between the base film and the recording layer. When the amount of the photoreactive monomer contained is excessively less than that of the polymer matrix containing the siloxane-based polymer, an erosion layer may not be formed. When the amount of the photoreactive monomer contained is excessively more than that of the polymer matrix containing the siloxane-based polymer, the thickness of the recording layer may become thin and the recording efficiency may become low.

[0040] When the coating solution is applied to the base film, the photoreactive monomer and the solvent can dissolve and penetrate at least a part of the base film. Thereafter, when a drying process for forming a coating layer is performed, the polymer matrix containing the siloxane-based polymer and the photoreactive monomer are cured or crosslinked to form an erosion layer. Also, the photoreactive monomer that has penetrated into the base film can be physically or chemically bonded to the base film.

[0041] Therefore, the erosion layer can contain a photoreactive monomer, and the erosion layer may be physically or chemically bonded to the base film. For example, the physical bond between the erosion layer and the base film may be achieved by the physical bonding of the photoreactive monomer contained in the erosion layer to the base film. Further, the coating layer can contain a polymer matrix containing a siloxane-based polymer and a photoreactive monomer.

[0042] On the other hand, a recording layer may be formed on the erosion layer, and the recording layer can contain a polymer matrix containing a siloxane-based polymer, a photoreactive monomer, and the like.

[0043] As described above, by forming the erosion layer on the base film, the adhesion between the optical film and the recording layer can be greatly improved. By adjusting the degree of formation of the erosion layer, the reduction in the recording efficiency of the photopolymer film can be minimized while achieving excellent mechanical properties such as heat resistance and heat and humidity reliability. The presence or absence of the erosion layer or the thickness of the erosion layer can be confirmed using the above-described photothermal infrared spectroscopy.

[0044] The erosion layer may have a thickness of 1.0 μm or more, 1.5 μm or more, 2.0 μm or more, 2.3 μm or more, 2.5 μm or more, and may also be 10.0 μm or less, 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, 6.0 μm or less, 5.5 μm or less, 5.0 μm or less, 4.5 μm or less. If the thickness of the erosion layer is excessively thin, the adhesion between the base film and the recording layer may decrease, and the heat resistance and heat and humidity reliability may deteriorate. If the thickness of the erosion layer is excessively thick, the thickness of the recording layer that is actually recorded may rather become thin and exhibit low recording efficiency.

[0045] The recording layer may have a thickness of 3.0 μm or more, 3.5 μm or more, 4.0 μm or more, and may also have a thickness of 8.0 μm or less, 7.0 μm or less, 6.8 μm or less, 6.7 μm or less. If the thickness of the recording layer is excessively thin, it may exhibit low recording efficiency. If the thickness of the recording layer is excessively thick, the thickness of the erosion layer may become thin, and the adhesion between the base film and the recording layer may be reduced.

[0046] The coating layer may have a thickness of 5.0 μm or more, 5.5 μm or more, 6.0 μm or more, and may also have a thickness of 20.0 μm or less, 15.0 μm or less, 10.0 μm or less.

[0047] The photopolymer film may include a coating layer including the erosion layer and the recording layer. The ratio of the thickness of the erosion layer to the coating layer may be 20.0% or more and 70.0% or less. For example, it may be 21.0% or more, 22.0% or more, 23.0% or more, 24.0% or more, 25.0% or more, 30.0% or more, 35.0% or more, and may also be 70.0% or less, 68.0% or less, 66.0% or less, 65.0% or less, 63.0% or less, 62.0% or less. If the ratio of the thickness is excessively low, the adhesion between the base film and the recording layer may be reduced, and the heat resistance and humidity resistance reliability may decrease. If the ratio of the thickness is excessively high, the thickness of the recording layer that is substantially recorded may rather become thin and may exhibit low recording efficiency.

[0048] The base film included in the photopolymer film according to the embodiment is not particularly limited as long as it is a base film capable of forming the erosion layer. For example, it may be a cellulose ester-based base film, a polyester-based base film, a poly(meth)acrylate-based base film, a polycarbonate-based base film, a cycloolefin-based (COP) base film, or an acrylic-based base film.

[0049] Alternatively, the base film may be a triacetyl cellulose (TAC)-based film, a polyethylene terephthalate (PET)-based base film, a polymethyl methacrylate (PMMA)-based base film, a cycloolefin (COP) base film, or an acrylic (Acryl) base film.

[0050] The thickness of the base film may be 20 μm or more, 30 μm or more, or 40 μm or more, and may also be 500 μm or less, 300 μm or less, 100 μm or less, 80 μm or less, or 60 μm or less. By satisfying the above-mentioned thickness, the base film can exhibit excellent mechanical properties, water resistance, low moisture permeability, and other characteristics.

[0051] The photopolymer film can be used for hologram recording applications.

[0052] According to another embodiment of the invention, there is provided a resin composition for forming a photopolymer film, which contains a polymer matrix containing a siloxane-based polymer or a precursor thereof, a photoreactive monomer, and an erosive solvent. With respect to 100% by weight of the coating liquid, the content of the erosive solvent is 25% by weight or more and 70% by weight or less.

[0053] As described above, when the resin composition for forming a photopolymer film is applied to the base film, the erosive solvent can dissolve and penetrate at least a part of the base film to form an erosion layer.

[0054] The coating liquid may contain 25% by weight or more and 70% by weight or less, 28% by weight or more and 68% by weight or less, 30% by weight or more and 65% by weight or less, or 35% by weight or more and 60% by weight or less of the erosive solvent with respect to 100% by weight of the coating liquid. By containing the erosive solvent in the above-mentioned content, an erosion layer can be formed.

[0055] The erosive solvent may be one or more selected from the group consisting of a ketone solvent, an ester solvent, a nitrogen compound solvent, a halogenated hydrocarbon solvent, and an aromatic hydrocarbon solvent. The ketone solvent may be, for example, methyl ethyl ketone, methyl isobutyl ketone, or acetone, and the ester solvent may be, for example, ethyl acetate.

[0056] Further, the resin composition for forming a photopolymer film may further contain a non-erosive solvent that is not the erosive solvent, and the non-erosive solvent may be, for example, isopropyl alcohol.

[0057] In 100% by weight of the total solvent contained in the resin composition for forming a photopolymer film, the erosive solvent may be contained in an amount of 35% to 90% by weight, 40% to 85% by weight, or 45% to 80% by weight. If the amount of the erosive solvent contained is excessively small, an erosion layer may not be formed, or an excessively thin erosion layer may be formed, resulting in low adhesion between the substrate film and the recording layer and a decrease in heat and humidity resistance reliability. If the amount of the erosive solvent contained is excessively large, the thickness of the recording layer where recording is substantially performed may rather become thin, showing low recording efficiency.

[0058] The resin composition for forming a photopolymer film according to the other embodiment may contain a polymer matrix containing a siloxane-based polymer or a precursor thereof. The polymer matrix containing the siloxane-based polymer or a precursor thereof can serve as a support for the photopolymer film produced from the resin composition.

[0059] Further, the polymer matrix containing the siloxane-based polymer or a precursor thereof can play a role in enhancing the refractive index modulation of the photopolymer film due to its relatively low refractive index (for example, n = 1.40 to 1.55). Also, the polymer matrix is a polyol-based matrix, contains a siloxane-based polymer, and when a catalyst, for example, a Pt-based catalyst, is introduced, rapid cross-linking of the matrix may be possible even at room temperature.

[0060] Further, the siloxane-based polymer can contain one or more silane functional groups (Si-H). Furthermore, the siloxane-based polymer can contain a repeating unit of the following Chemical Formula 1 or a repeating unit of Chemical Formula 2.

[0061]

Chemical formula

[0062] In each of the repeating units of Chemical Formula 1, R 1 ~R 2 may be the same as or different from each other, and is hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms, n is the number of repetitions of the repeating unit and is 1 to 10,000, In at least one repeating unit of the repeating unit, R 1 is an alkyl group having 1 to 10 carbon atoms, and R 2 may be hydrogen.

[0063]

Chemical formula

[0064] In each of the repeating units of Chemical Formula 2, R 11 ~R 13 may be the same as or different from each other, and is hydrogen, a halogen, or an alkyl group having 1 to 10 carbon atoms, n is the number of repetitions of the repeating unit and is 1 to 10,000, In at least one repeating unit of the repeating unit, R 11 and R 13 are alkyl groups having 1 to 10 carbon atoms, and R 12 is hydrogen, or R 11 and R 12 are alkyl groups having 1 to 10 carbon atoms, and R 13 is hydrogen.

[0065] The number average molecular weight (GPC measurement) of the siloxane-based polymer may be 200 to 4,000 or 350 to 2,500.

[0066] In addition to the siloxane-based polymer containing one or more silane functional groups (Si-H), the polymer matrix may contain a (meth)acrylic polyol containing two or more hydroxy groups (-OH). As a result, the polymer matrix contains all of the silane functional groups (Si-H) and hydroxy groups (-OH), and the molar ratio (SiH / OH) of the silane functional groups (Si-H) to the hydroxy groups (-OH) may be 0.80 or more and 3.5 or less. The lower limit may be, for example, 0.81 or more, 0.85 or more, 0.90 or more, 0.95 or more, 1.00 or more, or 1.05 or more, and the upper limit may be, for example, 3.4 or less, 3.3 or less, 3.2 or less, 3.2 or less, 3.05 or less, or 3.0 or less. Further, the types and contents of the siloxane-based polymer and the (meth)acrylic polyol in the polymer matrix can be controlled so as to satisfy the molar ratio (SiH / OH).

[0067] The resin composition for forming a photopolymer film may contain 25% by weight or more and 35% by weight or less, or 28% by weight or more and 33% by weight or less of the polymer matrix containing the siloxane-based polymer or a precursor thereof, based on 100% by weight of the solid content of the resin composition. When the polymer matrix containing the siloxane-based polymer or a precursor thereof is contained in an excessive amount, an erosion layer may not be formed, or an excessively thin erosion layer may be formed, resulting in low adhesion between the base film and the recording layer, and a decrease in heat and moisture resistance reliability. When the polymer matrix containing the siloxane-based polymer or a precursor thereof is contained in an excessively small amount, the thickness of the recording layer where recording is substantially performed may rather become thin, showing low recording efficiency.

[0068] Further, the content of the erosive solvent with respect to 100% by weight of the polymer matrix containing the siloxane-based polymer or its precursor may be 25% by weight or more and 65% by weight or less, 30% by weight or more and 60% by weight or less, or 35% by weight or more and 55% by weight or less. If the content of the erosive solvent relative to the polymer matrix containing the siloxane-based polymer or its precursor is excessively low, an erosion layer may not be formed, or an excessively thin erosion layer may be formed, resulting in low adhesion between the base film and the recording layer, and the heat and moisture resistance reliability may decrease. If the content of the erosive solvent is excessively high, the thickness of the recording layer where recording is substantially performed may rather become thin, showing low recording efficiency.

[0069] The resin composition for forming a photopolymer film according to the other embodiment may contain a photoreactive monomer.

[0070] The photoreactive monomer can include a polyfunctional (meth)acrylate monomer or a monofunctional (meth)acrylate monomer.

[0071] Examples of the photoreactive monomer include (meth)acrylate-based α,β-unsaturated carboxylic acid derivatives such as (meth)acrylate, (meth)acrylamide, (meth)acrylonitrile, or (meth)acrylic acid, or compounds containing a vinyl group or a thiol group.

[0072] Examples of the photoreactive monomer include polyfunctional (meth)acrylate monomers having a refractive index of 1.5 or more, or 1.53 or more, or 1.5 to 1.7. Such polyfunctional (meth)acrylate monomers having a refractive index of 1.5 or more, or 1.53 or more, or 1.5 to 1.7 can contain a halogen atom (such as bromine or iodine), sulfur (S), phosphorus (P), or an aromatic ring.

[0073] More specific examples of the polyfunctional (meth)acrylate monomer having a refractive index of 1.5 or more include bisphenol A modified diacrylate-based, fluorene acrylate-based (such as HR6022, etc. - Miwon Co., Ltd.), bisphenol fluorene epoxy acrylate-based (such as HR6100, HR6060, HR6042, etc. - Miwon Co., Ltd.), halogenated epoxy acrylate-based (such as HR1139, HR3362, etc. - Miwon Co., Ltd.), and the like.

[0074] As other examples of the photoreactive monomer, monofunctional (meth)acrylate monomers can be mentioned. The monofunctional (meth)acrylate monomer can contain an ether bond and a fluorene functional group inside the molecule. Specific examples of such monofunctional (meth)acrylate monomers include phenoxybenzyl (meth)acrylate, o-phenylphenol ethylene oxide (meth)acrylate, benzyl (meth)acrylate, 2-(phenylthio)ethyl (meth)acrylate, or biphenylmethyl (meth)acrylate, and the like.

[0075] On the other hand, the photoreactive monomer can have a weight average molecular weight of 50 g / mol to 1000 g / mol, or 200 g / mol to 600 g / mol. The weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method.

[0076] The resin composition for forming the photopolymer film can contain the photoreactive monomer in an amount of 6% by weight or more and 30% by weight or less, 8% by weight or more and 25% by weight or less, or 10% by weight or more and 20% by weight or less based on 100% by weight of the solid content of the composition. When the content of the photoreactive monomer is excessively low, an erosion layer may not be formed or an excessively thin erosion layer may be formed, resulting in low adhesion between the base film and the recording layer and a decrease in heat and moisture resistance reliability. When the content of the photoreactive monomer is excessively high, the thickness of the recording layer where recording is substantially performed may rather become thin, showing low recording efficiency.

[0077] In addition, the resin composition for forming the photopolymer film can contain 50 to 300 parts by weight of the photoreactive monomer with respect to 100 parts by weight of the polymer matrix containing the siloxane-based polymer. For example, the lower limit may be 50 parts by weight or more, 55 parts by weight or more, or 60 parts by weight or more, and the upper limit may be 300 parts by weight or less, 290 parts by weight or less, 285 parts by weight or less, or 280 parts by weight or less.

[0078] Also, the content of the erosive solvent with respect to 100% by weight of the photoreactive monomer may be 25% by weight or more and 65% by weight or less, 30% by weight or more and 60% by weight or less, or 35% by weight or more and 55% by weight or less. If the content of the erosive solvent with respect to the photoreactive monomer is excessively low, an erosion layer may not be formed or an excessively thin erosion layer may be formed, resulting in low adhesion between the base film and the recording layer and a decrease in heat and moisture resistance reliability. If the content of the erosive solvent is excessively high, the thickness of the recording layer where recording is substantially performed may rather become thin, showing low recording efficiency.

[0079] The resin composition for forming the photopolymer film according to the other embodiment can contain a photoinitiator. The photoinitiator is a compound activated by light or chemical radiation and can initiate the polymerization of a compound containing a photoreactive functional group such as the photoreactive monomer.

[0080] As the photoinitiator, commonly known photoinitiators can be used without significant restrictions. Specific examples thereof include a photo radical polymerization initiator, a photo cationic polymerization initiator, or a photo anionic polymerization initiator.

[0081] Specific examples of the photo radical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, thioxanthone derivatives, amine derivatives, and the like. More specifically, examples of the photo radical polymerization initiator include 1,3-di(t-butyldioxycarbonyl)benzophenone, 3,3’,4,4’’-tetrakis(t-butyldioxycarbonyl)benzophenone, 3-phenyl-5-isoxazolone, 2-mercapto benzimidazole, bis(2,4,5-triphenyl)imidazole, 2,2-dimethoxy-1,2-diphenylethane-1-one (product name: Irgacure651 / manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure369 / manufacturer: BASF), and bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium (product name: Irgacure784 / manufacturer: BASF), Ebecryl P-115 (manufacturer: SK entis), and the like.

[0082] Examples of the cationic photopolymerization initiator include diazonium salts, sulfonium salts, or iodonium salts. For example, sulfonic acid esters, imide sulfonates, dialkyl-4-hydroxy sulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η6-benzene)(η5-cyclopentadienyl)iron(II), etc. may be mentioned. Also, benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosylphthalimide, etc. may be mentioned. More specific examples of the cationic photopolymerization initiator include commercially available products such as Cyracure UVI-6970, Cyracure UVI-6974, and Cyracure UVI-6990 (manufacturer: Dow Chemical Co. in USA), Irgacure264 and Irgacure250 (manufacturer: BASF), or CIT-1682 (manufacturer: Nippon Soda).

[0083] Examples of the anionic photopolymerization initiator include borate salts. For example, butyryl chloride butyltriphenyl borate may be mentioned. More specific examples of the anionic photopolymerization initiator include commercially available products such as Borate V (manufacturer: Spectra group).

[0084] Also, the resin composition may use a one-molecule (Type I) or two-molecule (Type II) initiator. The (Type I) system for the free radical photopolymerization is, for example, an aromatic ketone compound combined with a tertiary amine, such as benzophenone, alkylbenzophenone, 4,4'-bis(dimethylamino)benzophenone (Michler's ketone), anthrone, and halogenated benzophenone, or a mixture of the above types. Examples of the two-molecule (Type II) initiator include benzoin and its derivatives, benzyl ketal, acylphosphine oxide, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bisacylphosphine oxide, phenylglyoxylate, camphorquinone, alpha-aminoalkylphenone, alpha-, alpha-dialkoxyacetophenone, 1-[4-(phenylthio)phenyl]octane-1,2-dione 2-(O-benzoyloxime), and alpha-hydroxyalkylphenone.

[0085] Also, the resin composition for forming a photopolymer film according to the other embodiment may further contain a fluorine-based compound. Since the fluorine-based compound has almost no reactivity and has stability and low refractive index characteristics, when added to the resin composition, it is possible to further reduce the refractive index of the polymer matrix and maximize the refractive index modulation with the monomer. The fluorine-based compound can serve as a plasticizer.

[0086] The fluorine-based compound can contain one or more functional groups selected from the group consisting of an ether group, an ester group, and an amide group and two or more difluoromethylene groups. More specifically, the fluorine-based compound can have a structure of Chemical Formula 4 below in which a functional group containing an ether group is bonded to both ends of a central functional group containing a direct bond or an ether bond between two difluoromethylene groups.

[0087]

Chemical Formula

[0088] In the formula (4), R 11 and R 12 are each independently a difluoromethylene group, R 13 and R 16 are each independently a methylene group, R 14 and R 15 are each independently a difluoromethylene group, R 17 and R 18 are each independently a polyalkylene oxide group, and m is an integer of 1 or more, or 1 to 10, or 1 to 3.

[0089] Preferably, in the formula (4), R 11 and R 12 are each independently a difluoromethylene group, R 13 and R 16 are each independently a methylene group, R 14 and R 15 are each independently a difluoromethylene group, R 17 and R 18 are each independently a 2-methoxyethoxymethoxy group, and m is an integer of 2.

[0090] The fluorine-based compound may have a refractive index of less than 1.45, or may be 1.3 or more and less than 1.45. As described above, since the photoreactive monomer has a refractive index of 1.5 or more, the fluorine-based compound can lower the refractive index of the polymer matrix due to a refractive index lower than that of the photoreactive monomer, and can maximize the refractive index modulation with the monomer.

[0091] Further, the resin composition for forming a photopolymer film may contain 20 to 200 parts by weight of the fluorine-based compound with respect to 100 parts by weight of the polymer matrix containing the siloxane-based polymer. For example, the lower limit may be 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 35 parts by weight or more, or 40 parts by weight or more, and the upper limit may be 200 parts by weight or less, 190 parts by weight or less, or 180 parts by weight or less.

[0092] Also, the content of the fluorine-based compound may be 30 parts by weight to 150 parts by weight, or 50 parts by weight to 110 parts by weight with respect to 100 parts by weight of the photoreactive monomer, and the refractive index of the polymer matrix may be 1.46 to 1.53. When the content of the fluorine-based compound is excessively reduced with respect to 100 parts by weight of the photoreactive monomer, the refractive index modulation value after recording becomes low due to the lack of low refractive components. When the content of the fluorine-based compound is excessively increased with respect to 100 parts by weight of the photoreactive monomer, haze may occur due to compatibility problems with other components, or problems such as elution of some fluorine-based compounds on the surface of the recording layer may occur.

[0093] The fluorine-based compound may have a weight average molecular weight (measured by GPC) of 300 or more, or 300 to 1000. The specific method for measuring the weight average molecular weight is as described above.

[0094] The polymer matrix containing the siloxane-based polymer or its precursor can further contain the fluorine-based compound.

[0095] On the other hand, the resin composition for forming a photopolymer film can further contain a photosensitive dye. The photosensitive dye serves as a sensitizing dye that sensitizes the photoinitiator. More specifically, the photosensitive dye can also serve as an initiator that is stimulated by the light irradiated on the photopolymer composition to initiate the polymerization of monomers and crosslinking monomers. The resin composition can contain 0.01% by weight to 1.00% by weight, or 0.05% by weight to 0.50% by weight of the photosensitive dye with respect to 100% by weight of the resin composition.

[0096] The examples of the photosensitive dyes are not greatly limited, and various commonly known compounds can be used. Specific examples of the photosensitive dyes include sulfonium derivatives of ceramidin, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose bengal, thionine, basic yellow, Pinacyanol chloride, rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, Quinaldine Red, crystal violet, Brilliant Green, Astrazon orange G, darrow red, pyronin Y, basic red 29, pyrylium iodide, Safranin O, cyanine, methylene blue, Azure A, or a combination of two or more of these.

[0097] The polymer matrix containing the siloxane-based polymer or its precursor can further contain the dye.

[0098] The resin composition for forming the photopolymer film can further contain other additives, catalysts, etc. For example, the resin composition can contain commonly known catalysts to promote the polymerization of the polymer matrix and the photoreactive monomer. Examples of the catalysts include platinum (Platinium)-based, rhodium (Rhodium)-based, iridium (Iridium)-based, rhenium (Rhenium)-based, molybdenum (Molybdenum)-based, iron (Iron)-based, nickel (Nickel)-based catalysts, alkali metal and alkaline earth metal catalysts. As non-metal-based catalysts, Lewis acids-based, carbene-based catalysts, etc. can be used.

[0099] Examples of the other additives include an antifoaming agent or a phosphate-based plasticizer. As the antifoaming agent, silicone-based reactive additives can be used, and an example thereof is Tego Rad2500. Examples of the plasticizer include phosphate compounds such as tributyl phosphate. The plasticizer can be added in a weight ratio of 1:5 to 5:1 together with the fluorine-based compound described above. The plasticizer may have a refractive index of less than 1.5 and a molecular weight of 700 or less.

[0100] The resin composition for forming the photopolymer can uniformly mix each component contained therein and be dried and cured at a temperature of 30°C or higher and 180°C or lower, 40°C or higher and 100°C or lower, 50°C or higher and 90°C or lower to produce the photopolymer film according to the above-described embodiment.

[0101] For example, the resin composition can preferentially and homogeneously mix the components forming the polymer matrix or its precursor, and the matrix can be crosslinked in a liquid state at room temperature using a Pt-based catalyst. The photoreactive monomer and the initiator can be added later to produce the final resin composition for forming the photopolymer film.

[0102] The resin composition can be mixed with each of the components contained therein using a commonly known mixer, stirrer, or mixer, etc. without any limitation. The temperature during the mixing process may be 0°C or higher and 100°C or lower, 10°C or higher and 80°C or lower, or 20°C or higher and 60°C or lower. The drying temperature may vary depending on the composition of the photopolymer, and for example, it can be promoted by heating at a temperature of 30°C to 180°C. During the drying, the resin composition may be in a state of being injected or coated onto a predetermined base film or mold.

[0103] The methods and apparatuses commonly used for coating the resin composition onto the base film can be used without any limitation. For example, bar coating methods such as Meyer bar, gravure coating method, 2 roll reverse coating method, vacuum slot die coating method, 2 roll coating method, etc. can be used.

[0104] According to still another embodiment of the invention, a hologram recording medium including the photopolymer film can be provided.

[0105] As described above, the photopolymer film has high adhesion between the recording layer and the base film, excellent heat and moisture resistance reliability, and optimized recording efficiency. A hologram recording medium including this film also has excellent heat and moisture resistance reliability and can optimize the recording efficiency.

[0106] The photopolymer film can be manufactured into a hologram for optical application in the entire visible range and the near ultraviolet region (300 - 800 nm) through a predetermined exposure process.

[0107] The method for recording a visual hologram on the hologram recording medium including the photopolymer film can be used with a commonly known method with little limitation.

[0108] For example, a visual hologram may be recorded by a method of selectively polymerizing a photoreactive monomer contained in the photopolymer film with an interferable laser.

[0109] According to still another embodiment of the invention, an optical element including the photopolymer film can be provided. Further, the optical element can include a hologram recording medium including the photopolymer film.

[0110] Specific examples of the optical element include an optical lens, a mirror, a deflection mirror, a filter, a diffusion screen, a diffraction member, a light guide, an optical waveguide, a holographic optical element having functions of a projection screen and / or a mask, a medium of an optical memory system, a light diffusion plate, an optical wavelength demultiplexer, a reflective or transmissive color filter, and the like.

[0111] An example of the optical element including the photopolymer film is a hologram display device. The hologram display device includes a light source unit, an input unit, an optical system, and a display unit. The light source unit is a part that irradiates a laser beam used to provide, record, and reproduce three-dimensional video information of an object in the input unit and the display unit. Further, the input unit is a part that pre-inputs three-dimensional video information of an object to be recorded in the display unit. For example, three-dimensional information of an object such as the intensity and phase of light for each space can be input to an electrically addressed liquid crystal SLM (electrically addressed liquid crystal SLM), and at this time, an input beam is used. The optical system may be composed of a mirror, a polarizer, a beam splitter, a beam shutter, a lens, and the like, and the optical system can distribute a laser beam emitted from the light source unit to an input beam sent to the input unit, a recording beam sent to the display unit, a reference beam, an erasing beam, a readout beam, and the like.

[0112] The display unit can receive three-dimensional video information of an object from the input unit, record it on a hologram plate composed of an optically addressed SLM (optically addressed SLM), and reproduce the three-dimensional video of the object. At this time, the three-dimensional video information of the object can be recorded by the interference of the input beam and the reference beam. The three-dimensional video information of the object recorded on the hologram plate can be reproduced as a three-dimensional video by the diffraction pattern generated by the read beam, and the erasure beam can be used to quickly remove the formed diffraction pattern. On the other hand, the hologram plate can move between the position where the three-dimensional video is input and the position where it is reproduced.

Effects of the Invention

[0113] According to the present invention, a photopolymer film with optimized recording efficiency, a composition for forming the same, a hologram recording medium including the same, and an optical element can be provided, which exhibit excellent heat and moisture-heat reliability while preventing deformation due to the external environment, along with improved adhesion between the base film and the recording layer.

Brief Description of the Drawings

[0114]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0115] The invention will be described in more detail in the following examples. However, the following examples are merely illustrative of the invention, and the content of the invention is not limited by the following examples.

[0116] <Production Example> Production Example 1: Production of (Meth)Acrylic Polyol 132 g of butyl acrylate, 420 g of ethyl acrylate, and 48 g of hydroxybutyl acrylate were placed in a 2 L jacket reactor and diluted with 1200 g of ethyl acetate. The reaction temperature was set at 60 to 70°C, and stirring was allowed to proceed for about 30 minutes to 1 hour. 0.42 g of n-dodecyl mercaptan (n-DDM) was additionally added, and stirring was further allowed to proceed for about 30 minutes. Thereafter, 0.24 g of AIBN as a polymerization initiator was added, and polymerization was allowed to proceed at the reaction temperature for 4 hours or more until the content of residual acrylate became less than 1%, to produce a (meth)acrylate copolymer in which a hydroxy group was located in the molecular chain (weight average molecular weight of about 300,000, OH equivalent of about 1802 g / equivalent).

[0117] Production Example 2: Production of Fluorine-Based Compound After putting 20.51 g of 2,2’-{oxybis[(1,1,2,2-tetrafluoroethane-2,1-diyl)oxy]}bis(2,2-difluoroethan-1-ol) into a 1000 mL flask, it was dissolved in 500 g of tetrahydrofuran, and while stirring at 0 °C, 4.40 g of sodium hydride (60% dispersion in mineral oil) was carefully added in multiple portions. After stirring at 0 °C for 20 minutes, 12.50 mL of 2-methoxyethoxymethyl chloride was slowly added dropwise. When it was confirmed by 1H NMR that all the reactants had been consumed, a liquid product of 29 g with a purity of 95% or more was obtained in a yield of 98% by work-up using dichloromethane. The weight average molecular weight of the produced fluorine-based compound was 586, and the refractive index measured with an Abbe refractometer was 1.361.

[0118] Examples and Comparative Examples: Production of Photopolymer Film Example 1 2.5 g of the (meth)acrylic polyol produced in Production Example 1, 0.10 g of a siloxane-based polymer containing a silane (Si-H) functional group (product name: Poly(methylhydrosiloxane), manufacturer: Sigma-Aldrich, Mn = ~390), 1.00 g of the fluorine-based compound produced in Production Example 2, 0.50 g of the dye HNu-640 (Spectra), and 0.60 g of a photoreactive monomer (high refractive index acrylate, refractive index 1.600, HR6042, Miwon) were mixed with the solvent in a light-blocked state so that the solid content was 25% of 100 parts by weight of the entire coating solution and in the ratio shown in Table 1 below, and stirred with a paste mixer for about 10 minutes. A Karstedt (Pt-based) catalyst was added for matrix crosslinking. After crosslinking, a Borate V (Spectra group) initiator was added to the coating solution, and then mixed for an additional 5 minutes or more to produce a coating solution. The coating solution was coated to a thickness of about 8 μm on a triacetyl cellulose (TAC) substrate film with a thickness of 40 μm using a Mayer bar and dried at 60°C within 10 minutes to form a coating layer.

[0119] Example 2 A photopolymer film was produced in the same manner as in Example 1, except that the solvent shown in Table 1 below was used.

[0120] Example 3 1.70 g of the (meth)acrylic polyol produced in Production Example 1 (0.52 g of solid content), 0.09 g of a siloxane-based polymer containing a silane (Si-H) functional group (product name: Poly(methylhydrosiloxane), manufacturing company: Sigma-Aldrich, Mn = ~390), 0.80 g of the fluorine-based compound produced in Production Example 2, 0.40 g of the dye HNu-640 (Spectra), 0.56 g of a photoreactive monomer (high refractive index acrylate, refractive index 1.600, HR6042, Miwon), 0.85 g of methyl ethyl ketone as a solvent, 0.75 g of methyl isobutyl ketone, 0.18 g of ethyl acetate, and 4.45 g of isopropyl alcohol were mixed with the solvent in a light-blocked state and stirred with a paste mixer for about 10 minutes. 0.09 g of a Karstedt (Pt-based) catalyst was added for matrix crosslinking. After crosslinking, 0.15 g of a Borate V (Spectra group) initiator was added to the coating solution, and then mixed for an additional 5 minutes or more to produce a coating solution. The coating solution was coated to a thickness of about 8 μm on a triacetyl cellulose (TAC) substrate film with a thickness of 40 μm using a Mayer bar and dried at 60°C within 10 minutes to form a coating layer. At this time, the coating solution was produced so that the weight ratio of the photoreactive monomer to the polymer matrix was 48:52 in the total mass of the coating solution.

[0121] On the other hand, in Table 2 below, the content of ethyl acetate corresponds to the combined content of the solvent (ethyl acetate) independently charged into the paste mixer and the solvent (ethyl acetate) contained in the "(meth)acrylic polyol produced in Production Example 1".

[0122] Examples 4 to 8 A photopolymer film was produced in the same manner as in Example 3, except that polyol, siloxane-based polymer, photoreactive monomer, fluorine-based compound, dye, initiator, catalyst, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and isopropyl alcohol were used in the contents shown in Table 2 below.

[0123] Comparative Example 1 A photopolymer film was produced in the same manner as in Example 1, except that the solvent shown in Table 1 below was used.

[0124] Comparative Examples 2 and 3 A photopolymer film was produced in the same manner as in Example 3, except that polyol, siloxane-based polymer, photoreactive monomer, fluorine-based compound, dye, initiator, catalyst, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and isopropyl alcohol were used in the contents shown in Table 2 below.

[0125]

Table 1

[0126]

Table 2

[0127] <Evaluation> 1. Measurement of the maximum reduction rate of the band area in the photothermal infrared spectroscopy (PTIR) graph Photothermal infrared spectroscopy (PTIR) was performed on the surface of the recording layer of the photopolymer films of the examples and comparative examples (specifically, the side of the recording layer facing the acrylic base material) at intervals of 1 μm in the thickness direction. The analysis conditions for the photothermal infrared spectroscopy are as follows.

[0128] <Photothermal infrared spectroscopy conditions> - Apparatus: mIRage (Photothermal Spectroscopy Corp.) - Light source: Tunable pulsed mid-IR Quantum Cascade Laser (1800~800 cm-1), probe laser (532 nm) - Spectral resolution: spectral resolution 1 cm-1, spatial resolution 500 nm - Microscope mode: Reflection mode -Detector: Avalanche photodiode detector

[0129] Thereafter, the results of the above-mentioned photo-thermal infrared spectroscopic analysis, which were analyzed at intervals of 1 μm in the thickness direction, were fitted with a Boltzmann sigmoid function according to the following formula 2. At this time, Fig. 3 is a graph obtained by fitting the results of the photo-thermal infrared spectroscopic analysis with a Boltzmann sigmoid function.

[0130]

Equation

[0131] In the above formula 2, A 1 : Initial y value, the band area of the peak of the carbonyl group on one side of the recording layer facing the base film A 2 : Final y value, the band area of the peak of the carbonyl group on one side of the recording layer close to the base film X 0 : X value with an intermediate y value (Center), the x value of the point where the band area of the carbonyl group in the recording layer becomes (A 1 +A 2 ) / 2 dx: Time constant, the rate of decrease from A 1 to A 2 .

[0132] Thereafter, in the graph obtained by differentiating the graph fitted with the Boltzmann sigmoid function once, the absolute value of the minimum value of the y value, that is, the maximum rate of decrease of the band area, is shown in Table 3 below. At this time, Fig. 4 is a graph obtained by differentiating the photo-thermal infrared spectroscopic analysis graph once. Also, in Table 3, when the measurement of the maximum rate of decrease of the band area, etc. was not performed, it was indicated by "-".

[0133] 2. Measurement of the thickness of the recording layer and the erosion layer The cross-sections of the photopolymer films of the examples and comparative examples were analyzed by a scanning electron microscope (SEM; Scanning Electron Microscope), and the thicknesses of the recording layer and the erosion layer were measured. Also, the ratio of the thickness of the erosion layer to the total thickness of the coating layer was calculated, and the results are shown in Table 3 below.

[0134] On the other hand, Fig. 5 is a photograph of the cross-section of the photopolymer film of Example 1 taken by SEM, Fig. 6 is a photograph of the cross-section of the photopolymer film of Example 2 taken by SEM, and Fig. 7 is a photograph of the cross-section of the photopolymer film of Comparative Example 1 taken by SEM.

[0135] 3. Adhesion (Cross-Cut) Evaluation After recording on the recording layer of the photopolymer films of the examples and comparative examples using a laser with a wavelength of 660 nm, a Cross-cut Test was performed on the recording layer.

[0136] Specifically, 100 (10×10 horizontally and vertically) grid-like cuts were made on the recording layer of the photopolymer film so that the horizontal and vertical sides were each 1 mm, and two peelings were performed using a tape (product name: CT-24, manufacturer: Nichiban). Thereafter, the state where the recording layer and the base film were separated and damaged or peeled was evaluated according to the following <Evaluation Criteria>, and the results are shown in Table 3 below.

[0137] On the other hand, in Fig. 8, (a) is a photograph of the adhesion evaluation result of Example 1, (b) is a photograph of the adhesion evaluation result of Example 2, and (c) is a photograph of the adhesion evaluation result of Comparative Example 1.

[0138] <Evaluation Criteria> 5B: The number of squares remaining without peeling is 100% of the total number of squares 4B: The number of squares remaining without peeling is 95% or more and less than 100% of the total number of squares 3B: The number of squares remaining without peeling is 85% or more and less than 95% of the total number of squares 2B: The number of cells remaining without peeling is 65% or more and less than 85% of the total number of cells 1B: The number of cells remaining without peeling is 35% or more and less than 65% of the total number of cells 0B: The number of cells remaining without peeling is 0% or more and less than 35% of the total number of cells

[0139] 4. Heat and Damp Heat Reliability Evaluation After recording on the recording layers of the photopolymer films of the examples and comparative examples using a laser with a wavelength of 660 nm, the heat and damp heat reliability evaluation was carried out.

[0140] Specifically, for the recording layer of the photopolymer film, the reflection spectrum was measured using a UV-Vis spectrophotometer to confirm the wavelength (λ, nm) at which the reflection peak appears.

[0141] Thereafter, for the heat reliability evaluation, the recording layer of the photopolymer film was attached to a glass plate with BPSA and placed at a temperature of 95 °C for 72 hours. Thereafter, the reflection spectrum of the recording layer of the photopolymer film was measured again with a UV-Vis spectrophotometer, and the degree of movement of the reflection peak was confirmed by the change amount of the wavelength (Δλ, nm), and the results are shown in Table 2 below.

[0142] Also, for the damp heat reliability evaluation, the recording layer of the photopolymer film was attached to a glass plate with BPSA and placed at a temperature of 85 °C and a humidity of 85% for 72 hours. Thereafter, the reflection spectrum of the recording layer of the photopolymer film was measured again with a UV-Vis spectrophotometer, and the degree of movement of the reflection peak was confirmed by the change amount of the wavelength (Δλ, nm), and the results are shown in Table 3 below.

[0143] 5. Recording Efficiency Evaluation After recording on the recording layers of the photopolymer films of the examples and comparative examples using a laser with a wavelength of 660 nm, the recording efficiency evaluation was carried out.

[0144] Specifically, for the recording layer of the photopolymer film, the reflection spectrum was measured using a UV-Vis spectrophotometer, and the wavelength (λ, nm) at which the reflection peak appeared was confirmed to measure the recording efficiency.

[0145]

Table 3

[0146] According to Table 3 above, the maximum reduction rate of the band area in the examples was 0.010 μm -1 ~0.095 μm -1 which satisfied the requirements, and an erosion layer of 20.0% - 70.0% was formed with respect to the coating layer (erosion layer + recording layer). It was confirmed that the adhesion was excellent, and the heat and humidity resistance reliability and recording efficiency were excellent.

[0147] On the other hand, in Comparative Example 1, almost no erosion layer was formed, and the adhesion, heat resistance, and humidity resistance reliability also deteriorated. In Comparative Example 2, the thickness of the erosion layer compared to the coating layer was formed as thin as 13.4%, resulting in deteriorated adhesion, heat resistance, and humidity resistance reliability. In Comparative Example 3, the thickness of the erosion layer compared to the coating layer was formed excessively thick at 70.6%, resulting in deteriorated recording efficiency.

Explanation of Symbols

[0148] 10: Coating layer 20: Recording layer 30: Erosion layer 40: Substrate film

Claims

1. A photopolymer film comprising a base film and a recording layer, wherein a graph derived from the result of performing photothermal infrared spectroscopy (PTIR; Photothermal Infrared Spectroscopy) in the thickness direction from one surface of the recording layer facing the base film has the band area of the carbonyl group (C=O group) contained in the recording layer on the Y-axis, and the distance in the thickness direction from one surface of the recording layer facing the base film on the X-axis, and the graph satisfies the following formula 1: [Formula 1] 0.010 μm －１ ≤ maximum reduction rate of band area ≤ 0.095 μm －１ In Formula 1, The maximum reduction rate of the band area is the absolute value of the minimum value of the y value in the graph obtained by first differentiating the graph.

2. The photopolymer film according to Claim 1, further comprising an erosion layer between the base film and the recording layer.

3. The photopolymer film includes a coating layer containing the erosion layer and the recording layer, The ratio of the thickness of the erosion layer to the coating layer is 20.0% or more and 70.0% or less. The photopolymer film according to Claim 2.

4. The erosion layer has a thickness of 1.0 μm or more and 10.0 μm or less. The photopolymer film according to Claim 2.

5. The base film is a cellulose ester-based base film, a polyester-based base film, a poly(meth)acrylate-based base film, a polycarbonate-based base film, a cycloolefin-based (COP) base film, or an acrylic-based base film. The photopolymer film according to Claim 1.

6. The base film is a triacetyl cellulose (TAC) film. The photopolymer film according to Claim 1.

7. The recording layer includes a polymer matrix containing a siloxane-based polymer and a photoreactive monomer. The photopolymer film according to Claim 1.

8. The polymer matrix containing the photoreactive monomer and the siloxane-based polymer has a weight ratio of 45:55 to 90:

10. The photopolymer film according to Claim 7.

9. The erosion layer contains a photoreactive monomer. The photopolymer film according to Claim 2.

10. A coating solution containing a polymer matrix containing a siloxane-based polymer or a precursor thereof, a photoreactive monomer, and an erosive solvent. A resin composition for forming a photopolymer film, wherein the content of the erosive solvent is 25% by weight or more and 70% by weight or less based on 100% by weight of the coating liquid.

11. The resin composition for forming a photopolymer film according to claim 10, wherein the erosive solvent is one or more selected from the group consisting of a ketone solvent, an ester solvent, a nitrogen compound solvent, a halogenated hydrocarbon solvent, and an aromatic hydrocarbon solvent.

12. A hologram recording medium including the photopolymer film according to claim 1.

13. An optical element including the photopolymer film according to claim 1.

Images