阅读说明：本技术 光聚合物组合物 (Photopolymer composition ) 是由 张锡勋 金宪 权洗铉 张影来 于 2020-01-10 设计创作，主要内容包括：本公开涉及用于形成全息图的光聚合物组合物、由所述光聚合物组合物制造的全息图记录介质、包括所述全息图记录介质的光学元件、和使用所述全息图记录介质的全息记录方法,所述光聚合物组合物包含：玻璃化转变温度为80℃或更低的聚合物基体或其前体；光反应性单体；低折射率基于氟的化合物；和光引发剂。(The present disclosure relates to a photopolymer composition for forming a hologram, a hologram recording medium manufactured from the photopolymer composition, an optical element including the hologram recording medium, and a hologram recording method using the hologram recording medium, the photopolymer composition comprising: a polymer matrix or a precursor thereof having a glass transition temperature of 80 ℃ or less; a photoreactive monomer; a low refractive index fluorine-based compound; and a photoinitiator.)

1. A photopolymer composition for forming a hologram comprising:

a polymer matrix or a precursor thereof having a glass transition temperature of 80 ℃ or less;

a photoreactive monomer;

a low refractive index fluorine-based compound; and

a photoinitiator.

2. The photopolymer composition for forming holograms of claim 1, wherein said polymer matrix or precursor thereof having a glass transition temperature of 80 ℃ or less comprises at least one polymer selected from the group consisting of: polyvinyl acetate, polyvinyl butyrate, polyvinyl formal, polyvinyl carbazole, polyacrylic acid, polymethacrylonitrile, polyacrylonitrile, poly-1, 2-dichloroethylene, ethylene-vinyl acetate copolymer, polymethyl methacrylate, syndiotactic polymethyl methacrylate, poly-alpha-vinyl naphthalate, polycarbonate, cellulose acetate, cellulose triacetate, cellulose acetate butyrate, polystyrene, poly-alpha-methylstyrene, poly-o-methylstyrene, poly-p-phenylstyrene, poly-p-chlorostyrene, poly-2, 5-dichlorostyrene, polyarylate, polysulfone, polyethersulfone, hydrogenated styrene-butadiene-styrene copolymer, a copolymer of a cyclic aliphatic ester of (meth) acrylic acid and methyl (meth) acrylate, a copolymer of a poly-alpha-vinylnaphthalate, a polycarbonate, a cellulose acetate butyrate, a polystyrene, Polyurethane, polytetrafluoroethylene, and polyvinylidene fluoride.

3. The photopolymer composition for forming holograms according to claim 1,

wherein the polymer matrix or precursor thereof having a glass transition temperature of 80 ℃ or less comprises polyvinyl acetate having a glass transition temperature of 20 ℃ to 60 ℃ and a weight average molecular weight of 50000 to 600000.

4. The photopolymer composition for forming holograms according to claim 1,

wherein the low refractive index fluorine-based compound has a refractive index of less than 1.45 and comprises at least one functional group selected from an ether group, an ester group, and an amide group and comprises two or more difluoromethylene groups.

5. The photopolymer composition for forming holograms according to claim 1,

wherein the low refractive index fluorine-based compound has the structure: wherein a functional group comprising an ether group is bonded to both ends of a central functional group comprising a direct bond or an ether bond between two difluoromethylene groups.

6. The photopolymer composition for forming holograms according to claim 1,

wherein the low refractive index fluorine-based compound comprises a compound represented by the following chemical formula 1:

[ chemical formula 1]

In the chemical formula 11, the first and second organic solvents,

R₁₁and R₁₂Each of which is independently a difluoromethylene group,

R₁₃and R₁₆Each of which is independently a methylene group,

R₁₄and R₁₅Each of which is independently a difluoromethylene group,

R₁₇and R₁₈Each independently is a polyalkylene oxide group, and

m is an integer of 1 or more.

7. The photopolymer composition for forming holograms according to claim 1,

wherein the photoreactive monomer comprises a multifunctional (meth) acrylate monomer or a monofunctional (meth) acrylate monomer.

8. The photopolymer composition for forming holograms of claim 1, comprising 1 to 80% by weight of said polymeric matrix or precursor thereof; 1 to 80 weight percent of the photoreactive monomer; 0.0001 to 10 wt% of the low refractive index fluorine-based compound; and 0.1 to 20 wt% of the photoinitiator.

9. The photopolymer composition for forming holograms of claim 1, comprising 10 to 250 parts by weight of the low refractive index fluorine-based compound based on 100 parts by weight of the photoreactive monomer.

10. The photopolymer composition for forming holograms according to claim 1,

wherein the photopolymer composition further comprises a phosphate based compound.

11. A hologram recording medium made from the photopolymer composition of claim 1.

12. An optical element comprising the hologram recording medium according to claim 11.

13. A holographic recording method comprising selectively polymerizing the photoreactive monomer contained in the photopolymer composition according to claim 1 by a coherent light source.

Technical Field

Cross Reference to Related Applications

The present application claims priority and benefit of korean patent application No. 10-2019-0009986, filed on 25.1.2019 to the korean intellectual property office, the disclosure of which is incorporated herein by reference in its entirety.

The present disclosure relates to a photopolymer composition, a hologram recording medium, an optical element, and a hologram recording method.

Background

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

When a photopolymer (photosensitive resin) is used, the optical interference pattern can be easily stored as a hologram by photopolymerization of a low molecular weight monomer. Therefore, the photopolymer can be used in various fields such as optical lenses; a mirror; a deflection mirror; a filter; a diffusing screen; a diffractive element; a light guide; a waveguide; a holographic optical element having a projection screen and/or a mask function; a medium of an optical storage system and a light diffusion plate; an optical wavelength multiplexer; reflective, transmissive color filters; and so on.

Generally, photopolymer compositions for hologram manufacture comprise a polymeric binder, monomers, and a photoinitiator, and a photosensitive film made from such compositions is irradiated with laser interference light to induce photopolymerization of local monomers.

In a portion where a relatively large amount of monomer is present during such photopolymerization, the refractive index becomes high. Whereas in the portion where a relatively large amount of the polymer binder is present, the refractive index is relatively lowered, and thus a refractive index modulation occurs, and a diffraction grating is produced by such a refractive index modulation. The refractive index modulation value n is influenced by the thickness and Diffraction Efficiency (DE) of the photopolymer layer, and the angular selectivity increases with decreasing thickness.

Recently, development of materials capable of maintaining stable holograms with high diffraction efficiency is required, and various attempts have also been made to manufacture a photopolymer layer having a large refractive index modulation value even with a thin thickness.

Disclosure of Invention

Technical problem

An object of the present disclosure is to provide a photopolymer composition for forming a hologram, which can achieve a higher refractive index modulation value and diffraction efficiency even while having a thin thickness, has a relatively fast reaction rate and thus can shorten a recording time, and can achieve high sensitivity to recording light and improve recording efficiency.

Another object of the present disclosure is to provide a hologram recording medium that can achieve a higher refractive index modulation value and diffraction efficiency even while having a thin thickness, has a relatively fast reaction rate and thus can shorten a recording time, and can achieve high sensitivity to recording light and improve recording efficiency.

It is still another object of the present disclosure to provide an optical element including the hologram recording medium described above.

It is still another object of the present disclosure to provide a hologram recording method including selectively polymerizing a photoreactive monomer contained in a hologram recording medium by coherent laser light.

Technical scheme

Provided herein is a photopolymer composition for forming a hologram comprising: a polymer matrix or a precursor thereof having a glass transition temperature of 80 ℃ or less; a photoreactive monomer; a low refractive index fluorine-based compound; and a photoinitiator.

Also provided herein are hologram recording media made from the above photopolymer compositions.

Also provided herein is an optical element comprising the hologram recording medium described above.

Also provided herein is a hologram recording method including selectively polymerizing the photoreactive monomer contained in the hologram recording medium described above by a coherent light source.

Hereinafter, the photopolymer composition, the hologram recording medium, the optical element, and the hologram recording method according to the embodiments of the present disclosure will be described in more detail.

As used herein, the term "(meth) acrylate" refers to either methacrylate or acrylate.

As used herein, the term "(co) polymer" refers to a homopolymer or a copolymer (including random, block, and graft copolymers).

As used herein, the term "hologram" refers to a recording medium that records optical information in the entire visible light range and near ultraviolet range (300nm to 800nm) by an exposure process, and examples thereof 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.

In the present specification, the alkyl group may be linear or branched, and the number of carbon atoms thereof is not particularly limited, but is preferably 1 to 40. According to one embodiment, the alkyl group has 1 to 20 carbon atoms. According to another embodiment, the alkyl group has 1 to 10 carbon atoms. According to yet another embodiment, the alkyl group has 1 to 6 carbon atoms. Specific examples of the alkyl group include: methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2-dimethylheptyl, 1-ethyl-propyl, 1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, and the like, but are not limited thereto.

In the present specification, an alkylene group is a divalent functional group derived from an alkane, and may be, for example, a linear, branched or cyclic methylene group, an ethylene group, a propylene group, an isobutylene group, a sec-butyl group, a tert-butyl group, a pentylene group, a hexylene group, or the like.

According to one embodiment of the present disclosure, there may be provided a photopolymer composition for forming a hologram comprising: a polymer matrix or a precursor thereof having a glass transition temperature of 80 ℃ or less; a photoreactive monomer; a low refractive index fluorine-based compound; and a photoinitiator.

The present inventors have found through experiments that when a photopolymer composition for forming a hologram comprising the above components is used, a hologram can be formed: which can achieve a higher refractive index modulation value and diffraction efficiency even while having a thin thickness, has a relatively fast reaction rate and thus can shorten the recording time, and can achieve high sensitivity to recording light and improve recording efficiency, thereby completing the present disclosure.

When the photopolymer composition for forming a hologram simultaneously uses a polymer matrix having a glass transition temperature of 80 ℃ or less or its precursor and a photoreactive monomer, the refractive index modulation value and diffraction efficiency can be more easily improved, and has a relatively fast reaction rate when a holographic medium is applied, and thus recording time can be shortened.

The polymer matrix or its precursor can serve as a support for the holographic recording medium and the final product made therefrom, and the photoreactive monomer can serve as a recording monomer. According to its use, a photoreactive monomer can be selectively polymerized on a polymer matrix during holographic recording, thus exhibiting refractive index modulation due to portions having different refractive indices.

The glass transition temperature of the polymer matrix or precursor thereof may be 80 ℃ or less, 60 ℃ or less, or 10 ℃ to 80 ℃, or 20 ℃ to 60 ℃, or 25 ℃ to 45 ℃. Since the polymer matrix or its precursor has the above-mentioned glass transition temperature, it is possible to ensure sufficient fluidity of the components in the photopolymer composition during recording while having thermal stability at room temperature.

The polymer matrix or its precursor may be used without particular limitation as long as it is a compound that can be generally used in a photopolymer composition that provides a holographic recording medium.

For example, a polymer matrix or precursor thereof having a glass transition temperature of 80 ℃ or less may comprise at least one polymer selected from the group consisting of: polyvinyl acetate, polyvinyl butyrate, polyvinyl formal, polyvinyl carbazole, polyacrylic acid, polymethacrylonitrile, polyacrylonitrile, poly-1, 2-dichloroethylene, ethylene-vinyl acetate copolymer, polymethyl methacrylate, syndiotactic polymethyl methacrylate, poly-alpha-vinyl naphthalate, polycarbonate, cellulose acetate, cellulose triacetate, cellulose acetate butyrate, polystyrene, poly-alpha-methylstyrene, poly-o-methylstyrene, poly-p-phenylstyrene, poly-p-chlorostyrene, poly-2, 5-dichlorostyrene, polyarylate, polysulfone, polyethersulfone, hydrogenated styrene-butadiene-styrene copolymer, a copolymer of a cyclic aliphatic ester of (meth) acrylic acid and methyl (meth) acrylate, a copolymer of a poly-alpha-vinylnaphthalate, a polycarbonate, a cellulose acetate butyrate, a polystyrene, Polyurethane, polytetrafluoroethylene, and polyvinylidene fluoride.

More specifically, the polymer matrix or its precursor having a glass transition temperature of 80 ℃ or less may include polyvinyl acetate having a glass transition temperature of 20 ℃ to 60 ℃, or 25 ℃ to 45 ℃ and a weight average molecular weight of 50000 to 600000.

The weight average molecular weight means a weight average molecular weight (unit: g/mol) measured by GPC method in terms of polystyrene conversion. In determining the weight average molecular weight according to polystyrene conversion measured by the GPC method, a conventionally known analysis apparatus, a detector (e.g., a refractive index detector) and an analytical column may be used. Commonly applied conditions for temperature, solvent and flow rate may be used. Specific examples of the measurement conditions may include a temperature of 30 ℃, a chloroform solvent, and a flow rate of 1 mL/min.

The glass transition temperature can be measured using a Dynamic Mechanical Analyzer (DMA), Differential Scanning Calorimetry (DSC), or the like. As a specific example of the method of measuring the glass transition temperature, there can be mentioned a method of measuring a change in heat in the range of-50 ℃ to 100 ℃ due to the temperature of the polymer matrix or precursor under a set condition of a temperature rise rate of 10 ℃/minute using a DSC (differential scanning calorimetry) measuring apparatus.

Since the low refractive index fluorine-based compound has stability with low reactivity and has low refractive characteristics, the refractive index of the polymer matrix may be lowered when added to the photopolymer composition, and thus, the refractive index modulation using monomers may be maximized and the diffraction efficiency of the finally manufactured hologram recording medium may also be improved.

The low refractive index fluorine-based compound may have a refractive index of less than 1.45, or 1.3 or more and less than 1.45. The low refractive index fluorine-based compound may further reduce the refractive index of the polymer matrix by a lower refractive index than the photoreactive monomer, thereby maximizing the modulation of the refractive index using the monomer.

Examples of the low refractive index fluorine-based compound may include a low refractive index fluorine-based compound including at least one functional group selected from an ether group, an ester group, and an amide group, and two or more difluoromethylene groups.

The low refractive index fluorine-based compound has a refractive index of less than 1.45, and may be a compound including at least one functional group selected from an ether group, an ester group, and an amide group, and two or more difluoromethylene groups.

Specifically, the low refractive index fluorine-based compound may have a structure in which a functional group including an ether group is bonded to both ends of a central functional group including a direct bond or an ether bond between two difluoromethylene groups.

Specific examples of the low refractive index fluorine-based compound may include a compound represented by the following chemical formula 1, in which a functional group including an ether group is bonded to both ends of a central functional group including an ether bond or a direct bond between two difluoromethylene groups.

[ chemical formula 1]

In chemical formula 1, R₁₁And R₁₂Each independently is difluoromethylene, R₁₃And R₁₆Each independently is methylene, R₁₄And R₁₅Each independently is difluoromethylene, R₁₇And R₁₈Each independently is a polyalkylene oxide group, and m is an integer of 1 or greater, alternatively 1 to 10, alternatively 1 to 3.

Preferably, in chemical formula 1, R₁₁And R₁₂Each independently is difluoromethylene, R₁₃And R₁₆Each independently is methylene, R₁₄And R₁₅Each independently is difluoromethylene, R₁₇And R₁₈Each independently is 2-methoxyethoxymethoxy, and m is an integer of 2.

Specifically, the low refractive index fluorine-based compound may be contained in an amount of 10 to 250 parts by weight, 20 to 150 parts by weight, or 40 to 100 parts by weight, based on 100 parts by weight of the photoreactive monomer.

When the content of the low refractive index fluorine-based compound with respect to the photoreactive monomer is too small, the refractive index modulation value after recording may be decreased due to the shortage of the low refractive index component. When the content of the low refractive index fluorine-based compound with respect to the photoreactive monomer is too large, haze may occur due to a problem of compatibility with other components, or a problem may occur in that a part of the fluorine-based compound is eluted on the surface of the coating layer.

The low refractive index 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.

Meanwhile, the photoreactive monomer may include a multifunctional (meth) acrylate monomer or a monofunctional (meth) acrylate monomer.

As described above, in a portion in which a monomer is polymerized during photopolymerization of a photopolymer composition and a relatively large amount of polymer is present, the refractive index becomes high. In a portion where a relatively large amount of the polymer binder is present, the refractive index becomes relatively low, refractive index modulation occurs, and a diffraction grating is generated due to such refractive index modulation.

Specifically, one example of the photoreactive monomer may include α, β -unsaturated carboxylic acid derivatives based on (meth) acrylic acid esters, such as (meth) acrylic acid esters, (meth) acrylamides, (meth) acrylonitriles, (meth) acrylic acids, and the like; or compounds containing vinyl or thiol groups.

One example of the photoreactive monomer may include a multifunctional (meth) acrylate monomer having a refractive index of 1.5 or more, 1.53 or more, or 1.5 to 1.7. The multifunctional (meth) acrylate monomer having a refractive index of 1.5 or more, or 1.53 or more, or 1.5 to 1.7 may contain a halogen atom (bromine, iodine, etc.), sulfur (S), phosphorus (P), or an aromatic ring.

More specific examples of the polyfunctional (meth) acrylate monomer having a refractive index of 1.5 or more include bisphenol a-modified diacrylate type, fluorene acrylate type (HR6022, etc. -Miwon Specialty Chemical), bisphenol fluorene epoxy acrylate type (HR6100, HR6060, HR6042, etc. -Miwon), halogenated epoxy acrylate series (HR1139, HR3362, etc. -Miwon).

Another example of the photoreactive monomer may include a monofunctional (meth) acrylate monomer. The monofunctional (meth) acrylate monomer may contain an ether bond and a fluorene functional group in the molecule. Specific examples of such monofunctional (meth) acrylate monomers include phenoxybenzyl (meth) acrylate, o-phenylphenol oxirane (meth) acrylate, benzyl (meth) acrylate, 2- (phenylthio) ethyl (meth) acrylate, biphenylmethyl (meth) acrylate, and the like.

Meanwhile, the weight average molecular weight of the photoreactive monomer may be 50g/mol to 1000g/mol, or 200g/mol to 600 g/mol. The weight average molecular weight means a weight average molecular weight measured by GPC method according to polystyrene conversion.

Meanwhile, the hologram recording medium of the embodiment may include a photoinitiator. The photoinitiator is a compound that is activated by light or actinic radiation and initiates polymerization of a compound containing a photoreactive functional group (e.g., a photoreactive monomer).

As the photoinitiator, generally known photoinitiators may be used without particular limitation, but specific examples thereof include a photo radical polymerization initiator, a photo cation polymerization initiator, or a photo anion polymerization initiator.

Specific examples of the photo radical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-arylglycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxy pyridinium salts, thioxanthone derivatives, amine derivatives, and the like. More specifically, examples of the photo radical polymerization initiator include 1, 3-bis (t-butyldioxycarbonyl) benzophenone, 3', 4,4 ″ -tetrakis (t-butyldioxycarbonyl) benzophenone, 3-phenyl-5-iso-benzophenoneOxazolone, 2-mercaptobenzimidazole, bis (2,4, 5-triphenyl) imidazole, 2-dimethoxy-1, 2-diphenylethan-1-one (product name: Irgacure 651/manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl-one (product name: Irgacure 184/manufacturer: BASF), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (product name: Irgacure 369/manufacturer: BASF), and bis (. eta.5-2, 4-cyclopentadien-1-yl) -bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium (product name: Irgacure 784/manufacturer: BASF), Ebecry P-115 (manufacturer: SK entis), and the like.

The photo cation polymerization initiator may include a diazonium salt,Salt or iodineSalts, and examples thereof include sulfonic acid esters, iminosulfonic acid salts, dialkyl-4-hydroxySalts, p-nitrobenzyl arylsulfonate, silanol-aluminum complexes, (. eta.6-benzene) (. eta.5-cyclopentadienyl) iron (II), and the like. Furthermore, benzoin tosylate, 2, 5-dinitrobenzyl tosylate, N-tosylphthalimide and the like can be mentioned. More specific examples of the photo-cationic polymerization initiator include commercially available products such as Cyracure UVI-6970, Cyracure UVI-6974 and Cyracure UVI-6990 (manufacturer: Dow Chemical Co., USA); irgacure 264 and Irgacure 250 (manufacturer: BASF); or CIT-1682 (manufacturer: Nippon Soda).

The photo-anionic polymerization initiator may be a borate, for example, butyrylchlorobutyltriphenylborate, etc. More specific examples of the photo-anionic polymerization initiator include commercially available products such as Borate V (manufacturer: Spectra Group).

Furthermore, the photopolymer composition of embodiments can include a monomolecular (type I) initiator or a bimolecular (type II) initiator. The (type I) systems used for free radical photopolymerization may comprise, for example, aromatic ketone compounds such as benzophenones, alkylbenzophenones, 4 '-bis (dimethylamino) benzophenone (Michler's ketone), anthrone and halobenzophenones, or mixtures of these types, in combination with tertiary amines. Bimolecular (type II) initiators may include benzoin and its derivatives, benzyl ketals, acyl phosphine oxides (e.g., 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bisacylphosphine oxides), phenylglyoxyl esters, camphorquinone, α -aminoalkylphenyl ketones, α -dialkoxyacetophenones, 1- [4- (phenylthio) phenyl ] octane-1, 2-dione 2- (O-benzoyl oxime), α -hydroxyalkylphenyl ketones, and the like.

The photopolymer composition of embodiments may comprise 1 to 80 weight percent of a polymer matrix or precursor thereof; 1 to 80% by weight of a photoreactive monomer; 0.0001 to 10 wt% of a low refractive index fluorine-based compound; and 0.1 to 20 wt% of a photoinitiator. When the photopolymer composition further comprises an organic solvent as described below, the content of the above components is based on the sum of the above components (the sum of the components other than the organic solvent).

The photopolymer composition may also comprise a phosphate based compound.

The phosphate ester-based compound serves as a plasticizer to lower the glass transition temperature of the polymer matrix and improve the flowability of the photoreactive monomer and the low refractive component, and may contribute to improving the formability of the photopolymer composition.

Specific examples of the phosphate-based compound include triphenyl phosphate, tricresyl phosphate, cresyldiphenyl phosphate, octyldiphenyl phosphate, diphenyldiphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.

The phosphate-based compound may be added together with the above fluorine-based compound in a weight ratio of 1:5 to 5: 1. The phosphate-based compound may have a refractive index of less than 1.5 and a molecular weight of 700 or less.

The photopolymer composition may comprise other additives, and examples of additives include defoamers. As the antifoaming agent, silicone-based additives can be used, and examples thereof are Tego Rad2500, BYK-3500, and the like.

Meanwhile, the photopolymer composition of the embodiment may further include a photoreactive dye.

The photosensitizing dye acts as a photosensitizing pigment to sensitize the photoinitiator. More specifically, the photosensitizing dye can be excited by light irradiated on the photopolymer composition and can also act as an initiator to initiate polymerization of the monomer and the crosslinking monomer.

Examples of the photosensitizing dye are not particularly limited, and various compounds generally known in the art may be used. Specific examples of photosensitizing dyes include those of ceramidonineDerivatives, 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 (Victoria blue R), azure blue, Quinaldine Red (Quinaldine Red), crystal violet, brilliant green, basic orange G (Astrazon orange G), Dalow Red (Darrow Red), pyronin Y (pyronin Y), basic Red 29, pyrane RedIodide, safranin o (safranin o), cyanine, methylene blue, azure a (azure a), or a combination of two or more thereof.

Meanwhile, the photopolymer composition may further include an organic solvent. Non-limiting examples of organic solvents include ketones, alcohols, acetates, ethers, and mixtures of two or more thereof.

Specific examples of such organic solvents include: ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, or isobutyl ketone; alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or tert-butanol; acetates such as ethyl acetate, isopropyl acetate or polyethylene glycol monomethyl ether acetate; ethers such as tetrahydrofuran or propylene glycol monomethyl ether; or a mixture of two or more thereof.

The organic solvent may be added at the time of mixing the components included in the photopolymer composition for manufacturing the hologram recording medium, or may be included in the photopolymer composition while adding the components in a state of being dispersed or mixed in the organic solvent. When the content of the organic solvent in the photopolymer composition is too low, the flowability of the photopolymer composition may be reduced, resulting in the occurrence of defects, such as the occurrence of stripe patterns, on the finally manufactured film. In addition, when the organic solvent is excessively added, the solid content is reduced, and coating and film formation are insufficient, so that physical and surface characteristics of the film may be deteriorated and defects may occur during the drying and curing process. Thus, the photopolymer composition can comprise an organic solvent such that the total solids content concentration of the included components is from 1 weight% to 70 weight%, or from 2 weight% to 50 weight%.

Meanwhile, according to another embodiment of the present disclosure, a hologram recording medium manufactured from the photopolymer composition may be provided.

The hologram recording medium may achieve a diffraction efficiency of 50% or more, 85% or more, or 85% to 99% at a thickness of 5 μm to 50 μm.

In a photopolymer composition for manufacturing a hologram recording medium, components contained therein are uniformly mixed, dried and cured at a temperature of 20 ℃ or more, and then subjected to a predetermined exposure process, thereby manufacturing a hologram for optical applications in the entire visible light range and near ultraviolet region (300nm to 800 nm).

In photopolymer compositions, the components forming the polymer matrix or its precursors are first mixed homogeneously, followed by mixing the other components together, thereby preparing the process for forming the hologram.

In the photopolymer composition, in order to mix the components contained therein, a mixing device, an agitator, a mixer, and the like generally known in the art may be used without particular limitation. The temperature during mixing may be from 0 ℃ to 100 ℃, preferably from 10 ℃ to 80 ℃, particularly preferably from 20 ℃ to 60 ℃.

At the same time, the components of the photopolymer composition that form the polymer matrix or precursor thereof are first homogenized and mixed, which may then be a liquid formulation that cures at a temperature of 20 ℃ or higher. The curing temperature may vary depending on the composition of the photopolymer and curing is facilitated, for example, by heating at a temperature of 30 ℃ to 180 ℃.

Upon curing, the photopolymer may be in a state that is injected or coated onto a predetermined substrate or mold.

Meanwhile, as a method of recording a visual hologram on a hologram recording medium manufactured from a photopolymer composition, a conventionally known method may be used without particular limitation, and a method described in the hologram recording method of the embodiment described below may be employed as one example.

Meanwhile, according to another embodiment of the present disclosure, a holographic recording method may be provided, which includes selectively polymerizing a photoreactive monomer included in a photopolymer composition by coherent laser light.

As described above, a medium in the form of an unrecorded visual hologram may be manufactured through the process of mixing and curing the photopolymer composition, and a visual hologram may be recorded on the medium through a predetermined exposure process.

The optical hologram may be recorded on a medium provided by the process of mixing and curing the photopolymer composition using known apparatus and methods under generally known conditions.

Meanwhile, according to another embodiment of the present disclosure, an optical element including a hologram recording medium may be provided.

Specific examples of the optical element include an optical lens; a mirror; a deflection mirror; a filter; a diffusing screen; a diffractive element; a light guide; a waveguide; a holographic optical element having a projection screen and/or a mask function; a medium of an optical storage system and a light diffusion plate; an optical wavelength multiplexer; reflective, transmissive color filters; and so on.

Examples of the optical element including the 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. 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. Further, the input unit is a portion to which three-dimensional image information of an object to be recorded on the display unit is input in advance, and for example, three-dimensional information of the object (for example, intensity and phase of light of each space) may be input into the electrically addressed liquid crystal SLM, where an input light beam may be used. The optical system may include mirrors, polarizers, beam splitters, beam shutters, lenses, and the like. The optical system may be allocated to transmit the laser beam emitted from the light source unit to an input beam of the input unit; a recording beam for transmitting a laser beam to the display unit; a reference beam; erasing the light beam; reading the light beam; and so on.

The display unit may receive three-dimensional image information of the object from the input unit, record it on a hologram plate including an optically addressed SLM, and reproduce a three-dimensional image of the object. In this case, three-dimensional image information of the object can be recorded by interference of the input beam and the reference beam. The three-dimensional image information of the object recorded on the hologram plate may be reproduced as a three-dimensional image by the diffraction pattern generated by the reading beam. The erasing beam can be used to quickly remove the formed diffraction pattern. Meanwhile, the hologram board may move between a position where the three-dimensional image is input and a position where the three-dimensional image is reproduced.

Advantageous effects

According to the present disclosure, it is possible to provide a photopolymer composition for forming a hologram, which can realize a higher refractive index modulation value and diffraction efficiency even while having a thin thickness, has a relatively fast reaction rate and thus can shorten a recording time, and can realize high sensitivity to recording light and improve recording efficiency, a hologram recording medium manufactured therefrom, an optical element including the same, and a hologram recording method using the hologram recording medium.

Detailed Description

Hereinafter, the present disclosure will be described in more detail by way of the following examples. However, these examples are given for illustrative purposes only and are not intended to limit the scope of the present disclosure thereto.

[ preparation example 1: preparation of Low refractive index fluorine-based Compound ]

20.51g of 2, 2' - ((oxybis (1,1,2, 2-tetrafluoroethane-2, 1-diyl)) bis (oxy)) bis (2, 2-difluoroethane-1-ol) were placed in a 1000ml flask, then dissolved in 500g of tetrahydrofuran and 4.40g of sodium hydride (60% dispersion in mineral oil) were added carefully in several portions while stirring at 0 ℃. After stirring at 0 ℃ for 20 minutes, 12.50ml of 2-methoxyethoxymethyl chloride were slowly added dropwise. When passing through¹When H NMR confirmed that the reaction had been completely consumed, all reaction solvent was removed under reduced pressure. After extraction three times with 300g of dichloromethane, the organic layer was collected, filtered with magnesium sulfate, and then all dichloromethane was removed under reduced pressure, thereby obtaining 29g of a liquid product having a purity of 95% or more in a yield of 98%.

Examples and comparative examples: preparation of photopolymer compositions

As shown in tables 1 and 2 below, a polymer matrix (manufactured by Aldrich), a photoreactive monomer (high refractive acrylate, refractive index of 1.600, HR6022[ Miwon ] was prepared]) The non-reactive low refractive index material of preparation example 1, tributyl phosphate (TBP), Safranin O [ Safranin O, manufactured by Aldrich]、Borate V(Spectra group)、Irgacure250(Salt, BASF) and methyl isobutyl ketone (MIBK) are mixed in a state of blocking light. For uniform mixing, the mixture was stirred at a temperature of 60 ℃ for 5 to 10 minutes. Further, the mixture was stirred at room temperature for about 10 minutes with a paste mixer to obtain a transparent coating solution, which was coated on a TAC substrate 80 μm thick to a thickness of 15 μm and dried at 60 ℃ for 30 minutes.

[ Experimental example: holographic recording

1) The photopolymer coated surfaces (hologram recording media) prepared in each of examples and comparative examples were laminated on a glass slide and fixed so that the laser light first passes through the glass surface at the time of recording.

2) Measurement of diffraction efficiency (. eta.)

Holographic recording is performed by interference of two interference lights (reference light and object light), and reflection recording is performed such that the two light beams are incident on opposite sides of the sample. The diffraction efficiency is changed according to the incident angle of the two light beams, and becomes non-oblique when the incident angles of the two light beams are the same. In non-oblique recording, since the incident angles of the two light beams are the same based on the normal, a diffraction grating is generated perpendicular to the film.

Recording was performed with a reflection type oblique system using a laser light having a wavelength of 532m (reference light 30 °, object light 40 °), and the diffraction efficiency (η) was calculated according to the following general formula 1.

[ general formula 1]

In the general formula 1, η is the diffraction efficiency, P_DThe output quantity (mW/cm) of the diffracted beam of the sample after recording²) And P_TOutput of transmitted beam (mW/cm) for the recorded sample²)。

[ Table 1]

Measurement results of experimental examples of the photopolymer composition (unit: g) of examples and the hologram recording medium prepared therefrom

[ Table 2]

Measurement results of experimental examples of photopolymer compositions (unit: g) of comparative examples and hologram recording media prepared therefrom

As seen from tables 1 and 2 above, the hologram media of the examples were determined to achieve a diffraction efficiency of 50% or more, while the hologram media of the comparative examples had a low diffraction efficiency of at most about 10%.

That is, as clearly determined from the evaluation results after hologram recording (532nm laser) for the examples, since fluidity of components in the polymer matrix and movement of the non-reactive low-refractive material (non-reactive fluorine-based compound and plasticizer) are ensured, higher refractive index modulation value and diffraction efficiency can be achieved.