KR102168680B1 - Photopolymer composition - Google Patents

Abstract

The present invention is a (meth)acrylate-based (co)polymer containing repeating units derived from alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms; Crosslinking agents including reactive functional groups; Photoreactive monomers; And it relates to a photopolymer composition comprising a photoinitiator.

Description

Photopolymer composition {PHOTOPOLYMER COMPOSITION}

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

The hologram recording media records information by changing the refractive index in the holographic recording layer in the media through an exposure process, and reads the change in the refractive index in the recorded media to reproduce information.

In the case of using a photopolymer (photosensitive resin, photopolymer), optical interference patterns can be easily stored as holograms by photopolymerization of low molecular weight monomers, so optical lenses, mirrors, deflection mirrors, filters, diffusion screens, diffraction members, light guides, waveguides , A holographic optical element having a function of a projection screen and/or a mask, a medium and a light diffusion plate of an optical memory system, a light wavelength divider, a reflective type, a transmission type color filter, and so on.

Typically, a photopolymer composition for producing a hologram includes a polymeric binder, a monomer, and a photoinitiator, and a photosensitive film prepared from such a composition is irradiated with laser interference light to induce localized photopolymerization of the monomer.

In the photopolymerization process, the refractive index is increased in a portion where a relatively large amount of monomers are present, and in a portion where a relatively large amount of a polymeric binder is present, the refractive index is relatively low, resulting in refractive index modulation, and a diffraction grating is generated by this refractive index modulation. The refractive index modulation value n is affected by the thickness of the photopolymer layer and the diffraction efficiency (DE), and the angular selectivity becomes wider as the thickness decreases.

In recent years, along with the demand for the development of a material capable of stably maintaining a hologram with high diffraction efficiency, various attempts have been made to manufacture a photopolymer layer having a thin thickness and a large refractive index modulation value.

The present invention is to provide a photopolymer composition that can more easily provide a photopolymer layer capable of realizing a high refractive index modulation value and high diffraction efficiency even in a thin thickness range.

In addition, the present invention is to provide a holographic recording medium including a photopolymer layer capable of realizing a high refractive index modulation value and high diffraction efficiency even in a thin thickness range.

Further, the present invention is to provide an optical element including a holographic recording medium.

In addition, the present invention is to provide a holographic recording method comprising the step of selectively polymerizing the photoreactive monomer contained in the photopolymer composition by electromagnetic radiation.

In the present specification, (meth)acrylate-based (co)polymer including repeating units derived from alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms; Crosslinking agents including reactive functional groups; Photoreactive monomers; And comprising a photoinitiator, a photopolymer composition is provided.

Further, in the present specification, a holographic recording medium prepared from the photopolymer composition is provided.

Further, in this specification, an optical element including the hologram recording medium is provided.

In addition, in the present specification, there is provided a holographic recording method comprising the step of selectively polymerizing a photoreactive monomer included in the photopolymer composition by a coherent light source.

Hereinafter, a photopolymer composition, a holographic recording medium, an optical element, and a holographic recording method according to a specific embodiment of the present invention will be described in more detail.

In this specification, (meth)acrylate means methacrylate or acrylate.

In the present specification, (co)polymer means a homopolymer or a copolymer (including a random copolymer, a block copolymer, and a graft copolymer).

In addition, in this specification, a hologram refers to a recording medium on which optical information is recorded in the entire visible range and near ultraviolet range (300-800 nm) through an exposure process, for example, in-line (Gabor )) Hologram, off-axis hologram, full-aperture pre-hologram, white light transmission hologram ("rainbow hologram"), Denisyuk hologram, biaxial reflection hologram, edge-literature ( It includes all visual holograms such as edge-literature) holograms or holographic stereograms.

In the present specification, the alkyl group may be a linear or branched chain, and the number of carbon atoms is not particularly limited, but is preferably 1 to 40. According to an exemplary embodiment, the alkyl group has 1 to 20 carbon atoms. According to another exemplary embodiment, the alkyl group has 1 to 10 carbon atoms. According to another exemplary 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, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl , n-heptyl, 1-methylhexyl, cyclopentylmethyl, cycloheptylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2 -Dimethylheptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, and the like, but are not limited thereto.

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

In addition, in this specification, "*" means a bond connected to another substituent.

According to an embodiment of the present invention, a (meth)acrylate-based (co)polymer comprising repeating units derived from alkenedioic acid or an anhydride thereof having 4 to 10 carbon atoms; Crosslinking agents including reactive functional groups; Photoreactive monomers; And comprising a photoinitiator, a photopolymer composition may be provided.

The present inventors have found that the hologram formed from the photopolymer composition including the (meth)acrylate-based (co)polymer including the repeating unit derived from the alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms is in a thin thickness range. It was confirmed through experiments that it was possible to implement a high refractive index modulation value and high diffraction efficiency, and that due to the structural stability of the matrix, shrinkage does not occur significantly during hologram formation, so that distortion of the hologram can be prevented. .

More specifically, since the photopolymer composition contains a (meth)acrylate-based (co)polymer including a repeating unit derived from alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms, without adding a catalyst The polymer matrix can be easily cured by simply applying heat.

In particular, the repeating unit derived from alkenedioic acid or an anhydride thereof having 4 to 10 carbon atoms can achieve a high crosslinking effect in the curing process, thereby minimizing volume shrinkage when recording holograms, and oxygen atoms are different Refractive index modulation can be maximized by maintaining compatibility with the components, thereby improving recording characteristics. In addition, by including the repeating unit derived from the alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms, the crosslinking density of the coating film prepared from the photopolymer composition is optimized, and thus a previously known polymer matrix (e.g. For example, it is possible to secure excellent durability compared to polyurethane resin, etc.).

The (meth)acrylate-based (co)polymer containing repeating units derived from alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms serves as a support for final products such as the photopolymer composition and films prepared therefrom In the hologram formed from the photopolymer composition, a portion having a different refractive index may serve to increase refractive index modulation.

The (meth)acrylate-based (co)polymer may include 1 to 40% by weight of repeating units derived from alkenedioic acid having 4 to 10 carbon atoms or an anhydride thereof.

When the content of the (meth)acrylate-based (co)polymer repeating unit derived from alkenedioic acid or its anhydride having 4 to 10 carbon atoms is too small, the number of crosslinking reactions due to the functional group of the repeating unit is reduced. Since the degree of crosslinking of the polymer matrix is lowered, it may be difficult to form a photopolymer film, and the above-described effects may not be realized. In addition, when the content of the (meth)acrylate-based (co)polymer is an alkenedioic acid having 4 to 10 carbon atoms or a repeating unit derived from its anhydride is too high, the crosslinking density of the polymer matrix is too high and exposure Photopolymerization may not occur smoothly due to the restriction of the movement of monomers, and thus photopolymer properties may not appear.

Specific examples of the (meth)acrylate-based (co)polymer including repeating units derived from alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms include maleic anhydride repeating units and alkyl acrylates having 1 to 10 carbon atoms (Co)polymers including repeating units can be presented.

The (meth)acrylate-based (co)polymer including repeating units derived from alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms has a weight average molecular weight of 100,000 to 1,000,000, and has a weight average molecular weight of -40°C to 10°C. It can have a glass transition temperature.

The weight average molecular weight refers to the weight average molecular weight (unit: g/mol) in terms of polystyrene measured by the GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, a commonly known analysis device, a detector such as a Refractive Index Detector, and a column for analysis can be used, and a commonly 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.

In addition, the repeating unit derived from an alkenedioic acid or an anhydride thereof having 4 to 10 carbon atoms includes a repeating unit derived from maleic anhydride, and the equivalent of maleic anhydride of the (meth)acrylate-based (co)polymer (equivalent weight) may be 100 to 3,000 g/mol, or 200 to 2,000 g/mol, or 300 to 1,500 g/mol, or 400 to 800 g/mol.

If the equivalent of maleic anhydride in the (meth)acrylate-based (co)polymer is too small or excessively increased, there may be a problem in that the film is not smoothly cured.

In particular, when the equivalent weight of maleic anhydride of the (meth)acrylate-based (co)polymer is 300 to 1,500 g/mol, preferably 400 to 800 g/mol, a relatively high refractive index modulation value and diffraction Efficiency may be implemented, and for example, a refractive index modulation value (Δn) of 0.011 or more or 0.012 or more and diffraction efficiency of 70% or 80% or more may be implemented.

The equivalent weight of maleic anhydride refers to the average molecular weight of the acrylate-based copolymer forming a matrix occupied by one maleic anhydride functional group, and the smaller the equivalent value, the higher the density of the functional groups, and the higher the equivalent value, the higher the functional group density. Becomes smaller. The example of the method for measuring the equivalent weight is not largely limited, for example, it can be measured by nuclear magnetic resonance method for quantitative analysis, and the glass transition temperature can be indirectly observed through DSC analysis. .

More specifically, the (meth)acrylate-based (co)polymer may include a (meth)acrylate repeating unit and a (meth)acrylate repeating unit in which a carboxyl group is located in a branched chain.

Examples of the (meth)acrylate repeating unit in which the carboxy group is located in the branched chain may be a repeating unit represented by the following formula (2).

[Formula 2]

In Formula 2, R ₄ is hydrogen or an alkyl group having 1 to 10 carbon atoms.

Preferably, in Chemical Formula 2, R ₄ may be a repeating unit derived from hydrogen, acrylic acid.

In addition, examples of the (meth)acrylate repeating unit include a repeating unit represented by the following formula (3).

[Chemical Formula 3]

In Formula 3, R ₅ is an alkyl group having 1 to 10 carbon atoms, R ₆ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and preferably in Formula 2, R ₅ is a C4 butyl group or a C1 methyl group And R ₆ may be a repeating unit derived from hydrogen, butyl acrylate or methyl acrylate.

On the other hand, the photopolymer composition of the embodiment includes a crosslinking agent including a reactive functional group together with a (meth)acrylate-based (co)polymer including a repeating unit derived from alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms. Including, the crosslinking density is optimized to ensure excellent durability against temperature and humidity compared to the existing matrix.Through this crosslinking density optimization, the mobility between a photoreactive monomer having a high refractive index and a component having a low refractive index is improved. By increasing the refractive index modulation, recording characteristics can be improved.

The crosslinking agent including the reactive functional group is not largely limited as long as it is a compound having a functional group capable of reacting with a (meth)acrylate-based (co)polymer including a repeating unit derived from the alkenedioic acid or anhydride thereof having 4 to 10 carbon atoms. Does not.

Specific examples of the crosslinking agent including the reactive functional group include a compound containing at least one reactive functional group selected from the group consisting of a hydroxy group, a carboxyl group, an amine group, a thiol group, an epoxy group, an acyl halide, oxazoline, carbodiimide, and isocyanate. I can.

Preferably, the crosslinking agent including the reactive functional group may be a polyol, an ethylline glycol diamine, a polyfunctional aziridine-based curing agent, a polyfunctional thiol curing agent, or a polyfunctional epoxy curing agent.

In order to optimize the crosslinking density and maximize the modulation of the refractive index as described above, a polyol having a hydroxyl equivalent of about 500 to 3,000 or 800 to 2,000, or 1200 to 1900 g/mol may be used as the polyol, and a number average molecular weight of 500 to 4,000 or Ethylline glycol diamine of 1,000 to 3,000 may be used, and a multifunctional aziridine-based curing agent having a molecular weight of 100 to 1,000 g/mol or 300 to 600 g/mol may be used.

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

As described above, in the photopolymerization process of the photopolymer composition, the monomer is polymerized to increase the refractive index in the portion where a relatively large amount of polymer is present, and the refractive index is relatively low in the portion where there is a relatively large amount of the polymeric binder, resulting in refractive index modulation. , A diffraction grating is generated by this refractive index modulation.

Specifically, an example of the photoreactive monomer is a (meth)acrylate-based α,β-unsaturated carboxylic acid derivative such as (meth)acrylate, (meth)acrylamide, (meth)acrylonitrile or (meth) Acrylic acid or the like, or a compound containing a vinyl group or a thiol group.

An example of the photoreactive monomer may be a polyfunctional (meth)acrylate monomer having a refractive index of 1.5 or more, or 1.53 or more, or 1.5 to 1.7, and such a refractive index is 1.5 or more, or 1.53 or more, or 1.5 to 1.7. The functional (meth)acrylate monomer may include a halogen atom (bromine, iodine, etc.), sulfur (S), phosphorus (P), or an aromatic ring.

More specific examples of the multifunctional (meth)acrylate monomer having a refractive index of 1.5 or more include sphenol A modified diacrylate series, fluorene acrylate series (HR6022, etc.-Miwon), bisphenol fluorene epoxy acrylate series (HR6100, HR6060, HR6042, etc.-Miwon) ), Halogenated epoxy acrylate series (HR1139, HR3362, etc.-Miwon).

Another example of the photoreactive monomer may be a monofunctional (meth)acrylate monomer. The monofunctional (meth)acrylate monomer may include an ether bond and a fluorene functional group in the molecule, and specific examples of such monofunctional (meth)acrylate monomers include phenoxy benzyl (meth)acrylate, o-phenyl Phenol ethylene oxide (meth)acrylate, benzyl (meth)acrylate, 2-(phenylthio)ethyl (meth)acrylate, or biphenylmethyl (meth)acrylate.

Meanwhile, the photoreactive monomer may 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 refers to the weight average molecular weight in terms of polystyrene measured by the GPC method.

Meanwhile, the photopolymer composition of the embodiment includes a photoinitiator. The photoinitiator is a compound activated by light or actinic radiation, and initiates polymerization of a compound containing a photoreactive functional group such as the photoreactive monomer.

As the photoinitiator, a commonly known photoinitiator may be used without great limitation, but specific examples thereof include a photoradical polymerization initiator, a photocationic polymerization initiator, or a photoanionic polymerization initiator.

Specific examples of the photo radical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxy pyridinium salts, thioxanthone Derivatives and amine derivatives. More specifically, as the photo-radical polymerization initiator, 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: Irgacure 651 / Manufacturer: BASF), 1-hydroxy-cyclohexyl-phenyl -ketone (product name:Irgacure 184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: Irgacure 369 / manufacturer: BASF), and bis(η5-2, 4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium (product name: Irgacure 784 manufacturer: BASF), Ebecryl P-115 (manufacturer: SK entis), H-Nu 254 (manufacturer: Spectra Group Limited), and the like.

Examples of the photocationic polymerization initiator include diazonium salt, sulfonium salt, or iodonium salt, and examples thereof include sulfonic acid ester, imide sulfonate, dialkyl-4 -Hydroxysulfonium salt, aryl sulfonic acid-p-nitrobenzyl ester, silanol-aluminum complex, (η6-benzene) (η5-cyclopentadienyl) iron (II), and the like. Further, benzoin tosylate, 2,5-dinitro benzyl tosylate, N-tosylphthalic acid imide, and the like are also mentioned. More specific examples of the photocationic polymerization initiator, Cyracure UVI-6970, Cyracure UVI-6974 and Cyracure UVI-6990 (manufacturer: Dow Chemical Co. in USA) or 　Irgacure　264 and Irgacure　250　 (manufacturer: BASF) or CIT-1682 Commercial products, such as (manufacturer: Nippon Soda), are mentioned.

Examples of the photoanionic polymerization initiator include a borate salt, and examples thereof include butyryl chlorine butyl triphenyl borate (BUTYRYL CHOLINE BUTYLTRIPHENYLBORATE). More specific examples of the photoanionic polymerization initiator include commercially available products such as Borate V (manufacturer: Spectra group).

In addition, the photopolymer composition of the above embodiment may use a single molecule (type I) or two molecule (type II) initiator. (Type I) systems for free radical photopolymerization are, for example, aromatic ketone compounds in combination with tertiary amines, such as benzophenone, alkylbenzophenone, 4,4'-bis(dimethylamino)benzophenone (Michler's ) Ketones), anthrones and halogenated benzophenones or mixtures of the above types. Examples of the bimolecular (type II) initiator include benzoin and its derivatives, benzyl ketal, acylphosphine oxide, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bisacilophosphine oxide, phenylgly Oxyl ester, campoquinone, alpha-aminoalkylphenone, alpha-, alpha-dialkoxyacetophenone, 1-[4-(phenylthio)phenyl]octane-1,2-dione 2-(O-benzoyloxime) and alpha -Hydroxyalkylphenone, etc. are mentioned.

The photopolymer composition may include 1% to 80% by weight of the polymer matrix or a precursor thereof; 5 to 80% by weight of a crosslinking agent including the reactive functional group; 5% to 80% by weight of the photoreactive monomer; And 0.1% to 15% by weight of the photoinitiator; and as described below, when the photopolymer composition further includes an organic solvent, the content of the above-described components is the sum of these components (excluding organic solvents). It is based on the sum of ingredients).

The photopolymer composition may further include a fluorine-based compound. Since the fluorine-based compound has stability with little reactivity and has low refractive properties, it is possible to lower the refractive index of the polymer matrix when added to the photopolymer composition, thereby maximizing the modulation of the refractive index with the monomer.

The fluorine-based compound may include one or more functional groups and two or more difluoromethylene groups selected from the group consisting of an ether group, an ester group, and an amide group. More specifically, the fluorine-based compound may have a structure of the following Formula 4 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 of two difluoromethylene groups.

[Formula 4]

In Formula 4, R ₁₁ and R ₁₂ are each independently a difluoromethylene group, R ₁₃ and R ₁₆ are each independently a methylene group, and 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.

Preferably, in Formula 4, R ₁₁ and R ₁₂ are each independently a difluoromethylene group, R ₁₃ and R ₁₆ are each independently a methylene group, and R ₁₄ and R ₁₅ are each independently a difluoromethylene group Group, R ₁₇ and R ₁₈ are each independently a 2-methoxyethoxymethoxy group, and m is an integer of 2.

The fluorine-based compound may have a refractive index of less than 1.45, or 1.4 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 through a refractive index lower than that of the photoreactive monomer, thereby maximizing the modulation of the refractive index with the monomer.

Specifically, the fluorine-based compound content may be 30 parts by weight to 150 parts by weight, or 50 parts by weight to 110 parts by weight, based on 100 parts by weight of the photoreactive monomer.

If the content of the fluorine-based compound is excessively decreased with respect to 100 parts by weight of the photoreactive monomer, the modulated value of the refractive index after recording is lowered due to the lack of a low refractive component, and the content of the fluorine-based compound is excessively increased with respect to 100 parts by weight of the photoreactive monomer. If the crosslinking degree is low, film formation may not be possible, or compatibility may be poor, resulting in a high defect rate, and haze may occur due to compatibility problems with other components or some fluorine-based compounds may be eluted to the surface of the coating layer. .

The fluorine-based compound may have a weight average molecular weight (GPC measurement) of 300 or more, or 300 to 1000. A specific method of measuring the weight average molecular weight is as described above.

Meanwhile, the photopolymer composition may further include a photosensitive dye. The photosensitive dye serves as a sensitizing dye that sensitizes the photoinitiator. More specifically, the photosensitive dye is stimulated by light irradiated to the photopolymer composition to initiate polymerization of the monomer and the crosslinking monomer. can do. The photopolymer composition may include 0.01 to 30% by weight, or 0.05 to 20% by weight of a photosensitive dye.

Examples of the photosensitive dye are not limited to a great extent, and various commonly known compounds may be used. Specific examples of the photosensitive dye include sulfonium derivatives of ceramidonin, new methylene blue, thioerythrosine triethylammonium, and 6-acetylamino-2-methylcera. Midonine (6-acetylamino-2-methylceramidonin), eosin (eosin), erythrosine (erythrosine), rose bengal (rose bengal), thionine (thionine), basic yellow (basic yellow), pinacyanol chloride (Pinacyanol chloride) ), rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, Quinaldine Red, crystal violet (crystal violet), Brilliant Green, Astrazon orange G, darrow red, pyronin Y, basic red 29, pyryllium I (pyrylium iodide), safranin O, cyanine, methylene blue, Azure A, or a combination of two or more thereof.

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

Specific examples of such an organic solvent include ketones such as methyl ethylkenone, methyl isobutyl ketone, acetylacetone or isobutyl ketone; Alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, or t-butanol; Acetates such as ethyl acetate, i-propyl acetate, or polyethylene glycol monomethyl ether acetate; Ethers such as tetrahydrofuran or propylene glycol monomethyl ether; Or a mixture of two or more of these may be mentioned.

The organic solvent may be added at a time when the components included in the photopolymer composition are mixed, or may be included in the photopolymer composition while each component is added in a dispersed or mixed state in the organic solvent. If the content of the organic solvent in the photopolymer composition is too small, the flowability of the photopolymer composition decreases, and thus defects such as streaks may occur in the finally produced film. In addition, when an excessive amount of the organic solvent is added, the solid content is lowered, coating and film formation are not sufficiently performed, so that physical properties or surface properties of the film may be deteriorated, and defects may occur during drying and curing. Accordingly, the photopolymer composition may include an organic solvent such that the concentration of the total solids of the components included is 1% to 70% by weight, or 2 to 50% by weight.

The photopolymer composition may further include other additives, catalysts, and the like. For example, the photopolymer composition may further include a commonly known catalyst to promote polymerization of the polymer matrix or photoreactive monomer. Examples of the catalyst include tin octanoate, zinc octanoate, dibutyltin dilaurate, dimethylbis[(1-oxonedecyl)oxy]stanane, dimethyltin dicarboxylate, zirconium bis(ethylhexa Noate), zirconium acetylacetonate, p-toluenesulfonic acid or tertiary amines, such as 1,4-diazabiclo[2.2.2]octane, diazabiclononane, diazabiccloundecan , 1,1,3,3-tetramethylguanidine, 1,3,4,6,7,8-hexahydro-1-methyl-2H-pyrimido (1,2-a) pyrimidine, and the like. .

Examples of the other additives include a defoaming agent or a phosphate-based plasticizer, and a silicone-based reactive additive may be used as the defoaming agent, and examples thereof include Tego Rad 2500. Examples of the plasticizer may include a phosphate compound such as tributyl phosphate, and the plasticizer may be added in a weight ratio of 1:5 to 5:1 together with the above-described fluorine-based compound. The plasticizer may have a refractive index of less than 1.5 and a molecular weight of 700 or less.

Meanwhile, the above-described fluorine-based compound or phosphate-based compound has a lower refractive index than that of the photoreactive monomer, and thus, it is possible to maximize the modulation of the refractive index of the photopolymer composition by lowering the refractive index of the polymer matrix. In addition, the phosphate-based compound may function as a plasticizer, thereby lowering the glass transition temperature of the polymer matrix to increase the moldability of the photopolymer composition or to facilitate the movement of the monomer.

The photopolymer composition may be used for holographic recording.

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

As described above, when the photopolymer composition of the embodiment is used, a hologram capable of implementing a refractive index modulation value and high diffraction efficiency significantly improved compared to previously known holograms while having a thinner thickness may be provided.

The hologram recording medium may implement a refractive index modulation value (n) of 0.009 or more, 0.010 or more, or 0.011 or more, or 0.012 or more even at a thickness of 5 μm to 30 μm, and the upper limit is not largely limited, for example, 0.020 or less. Can be

In addition, the hologram recording medium may implement diffraction efficiency of 50% or more, or 70% or more, or 80% or more, or 85% or more at a thickness of 5 μm to 30 μm, and the upper limit thereof is not largely limited, examples For example, it may be less than 99.9%.

The photopolymer composition of the embodiment is uniformly mixed with each component contained therein, dried and cured at a temperature of 20° C. or higher, and then subjected to a predetermined exposure process to provide the entire visible range and near-ultraviolet rays (300 to 800 nm). ) Can be produced as a hologram for optical application.

In the photopolymer composition of the embodiment, a component forming a polymer matrix or a precursor thereof is first homogeneously mixed, and a linear silane crosslinking agent is later mixed with a catalyst to prepare a hologram formation process.

In the photopolymer composition of the embodiment, a commonly known mixer, agitator, or mixer may be used without any other limitation for mixing each component contained therein, and the temperature in the mixing process is 0°C to 100°C, preferably May be 10 ℃ to 80 ℃, particularly preferably 20 ℃ to 60 ℃.

On the other hand, in the photopolymer composition of the embodiment, a component forming a polymer matrix or a precursor thereof is first homogenized and mixed, and then, at the time when a linear silane crosslinking agent is added, the photopolymer composition is cured at a temperature of 20°C or higher. Can be.

The curing temperature may vary depending on the composition of the photopolymer, and is accelerated by heating to a temperature of 30° C. to 180° C., for example.

During the curing, the photopolymer may be injected or coated on a predetermined substrate or mold.

On the other hand, the method of recording a visual hologram on a holographic recording medium prepared from the photopolymer composition can be used without great limitation, a commonly known method, and the method described in the holographic recording method of the embodiment described below will be adopted as an example. I can.

Meanwhile, according to another embodiment of the present invention, a holographic recording method may be provided, including the step of selectively polymerizing a photoreactive monomer included in the photopolymer composition by a coherent light source.

As described above, a medium in which a visual hologram is not recorded may be prepared 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.

A visual hologram may be recorded on a medium provided through the process of mixing and curing the photopolymer composition using a known apparatus and method under commonly known conditions.

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

Specific examples of the optical element include an optical lens, a mirror, a deflecting mirror, a filter, a diffusion screen, a diffractive member, a light guide, a waveguide, a projection screen and/or a holographic optical element having a function of a mask, and a medium and light of an optical memory system. Diffusion plates, optical wavelength dividers, reflective and transmissive color filters.

An example of an optical element including the hologram recording medium may be 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 irradiates a laser beam used to provide, record, and reproduce 3D image information of an object in the input unit and the display unit. In addition, the input unit is a part for pre-inputting 3D image information of an object to be recorded on the display. For example, 3D of an object such as the intensity and phase of light in each space is applied to an electrically driven liquid crystal SLM (SLM). Dimensional information can be input, and in this case, an input beam can be used. The optical system may be composed of a mirror, a polarizer, a beam splitter, a beam shutter, a lens, etc., and the optical system includes an input beam that sends a laser beam emitted from the light source to an input, a recording beam to a display, a reference beam, an erase beam, and a dock. It can be distributed with a beam beam.

The display unit may receive 3D image information of an object from an input unit, record it on a hologram plate made of an optically addressed SLM (SLM), and reproduce a 3D image of the object. At this time, the 3D image information of the object may be recorded through interference between the input beam and the reference beam. The 3D image information of the object recorded on the hologram plate may be reproduced as a 3D image by a diffraction pattern generated by a read beam, and an erase beam may be used to quickly remove the formed diffraction pattern. Meanwhile, the hologram plate may be moved between a position to input a 3D image and a position to play it.

According to the present invention, a photopolymer composition capable of realizing a high refractive index modulation value and high diffraction efficiency even in a thin thickness range, a hologram recording medium, an optical element, and a holographic recording method using the same can be provided.

The invention will be described in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

[Production Example]

Manufacturing example One: Maleic acid Containing repeating units derived from anhydrides ( Met ) Acrylate system Preparation of copolymer

In a 2L reactor, 88 g of butyl acrylate, 5 g of methyl acrylate, and 7 g of maleic anhydride were added, followed by diluting with 397 g of ethyl acetate. Then, the reactor was set to 70° C., and the diluted solution was stirred for 30 minutes. Then, 0.01 g of N-Dodecyl mercaptane was additionally added, followed by stirring for 30 minutes. Then, 0.12 g of AIBN, which is a polymerization initiator, was added and polymerization was performed for 18 hours, confirming that the residual acrylate content was less than 1% by IR, and the reaction was completed to obtain a (meth)acrylate-based copolymer. (Weight average molecular weight about 700,000, equivalent weight of maleic anhydride = 1400.9 g/mol, glass transition temperature (Tg) -30℃)

Manufacturing example 2: Maleic acid Containing repeating units derived from anhydrides ( Met ) Acrylate system Preparation of copolymer

85 g of butyl acrylate and 9.2 g of maleic anhydride were added to a 2L reactor, and diluted with 375 g of ethyl acetate. Then, the reactor was set to 70° C., and the diluted solution was stirred for 30 minutes. Then, 0.01 g of N-Dodecyl mercaptane was additionally added, followed by stirring for 30 minutes. Then, 0.12 g of AIBN, which is a polymerization initiator, was added and polymerization was performed for 18 hours, confirming that the residual acrylate content was less than 1% by IR, and the reaction was completed to obtain a (meth)acrylate-based copolymer. (Weight average molecular weight about 600,000, equivalent weight of maleic anhydride = 1004 g/mol, glass transition temperature (Tg) -26.2℃)

Manufacturing example 3: Maleic acid Containing repeating units derived from anhydrides ( Met ) Acrylate system Preparation of copolymer

88 g of butyl acrylate and 17 g of maleic anhydride were added to a 2L reactor, and diluted with 419 g of ethyl acetate. Then, the reactor was set to 70° C., and the diluted solution was stirred for 30 minutes. Then, 0.01 g of N-Dodecyl mercaptane was additionally added, followed by stirring for 30 minutes. Then, 0.12 g of AIBN, which is a polymerization initiator, was added and polymerization was performed for 18 hours, confirming that the residual acrylate content was less than 1% by IR, and the reaction was completed to obtain a (meth)acrylate-based copolymer. (Weight average molecular weight about 600,000, equivalent weight of maleic anhydride = 605.7 g/mol, glass transition temperature (Tg) -8.8℃)

Manufacturing example 4: Maleic acid Containing repeating units derived from anhydrides ( Met ) Acrylate system Preparation of copolymer

In a 2L reactor, 40 g of butyl acrylate, 40 g of methyl acrylate, and 20 g of maleic anhydride were added, followed by diluting with 200 g of ethyl acetate. Then, the reactor was set to 70° C., and the diluted solution was stirred for 30 minutes. Then, 0.05 g of N-Dodecyl mercaptane was additionally added, followed by stirring for 30 minutes. Then, 0.2 g of AIBN, a polymerization initiator, was added, and polymerization was carried out for 18 hours, confirming that the residual acrylate content was less than 1% by IR, and the reaction was completed to obtain a (meth)acrylate-based copolymer. (Weight average molecular weight about 400,000, equivalent weight of maleic anhydride = 490.3 g/mol, glass transition temperature (Tg) -2.8℃)

[Example: Preparation of photopolymer composition]

Example 1

As described in Table 1 or Table 2 below, the (meth)acrylate-based copolymer obtained in Preparation Examples 1 to 3, photoreactive monomer (high refractive acrylate, refractive index 1.600, HR6042 [Miwon]), Polyol-1 (Acrylic polyol, OH equivalent weight = 1800 g/mol) or Polyol-2 (Acrylic polyol, OH equivalent weight = 1440 g/mol), EG (Ethylene Glycol) Diamine (Mn=2000, manufactured by Aldrich), Aziridine hardener (Trimethylolpropane tris (2-methyl-1-aziridine propionate), molecular weight 467g/mol), dye (New methylene blue N, Ethyl violet, Safranine O, Eosin Y, Rhodamine 6G (Aldrich)), tertiary amine (CN-373, CN-) 386 (Sartomer)], Irganox 250 ([4-methylphenyl-(4-(2-methylpropyl)phenyl)]iodonium hexafluorophosphate, (Ciba)), and methyl isobutyl ketone (MIBK) were mixed in a light-blocking state. , Paste mixer was stirred for 10 minutes to obtain a transparent coating solution.

The coating solution was coated on a TAC substrate having a thickness of 80 μm using a meyer bar, and heat-treated at 60° C. for 30 minutes to prepare a 15 μm photopolymer coating film.

[Experimental Example: Holographic Record]

(1) The photopolymer coated surface prepared in each of the above Examples and Comparative Examples was laminated on a slide glass, and when recording, the laser was fixed to pass through the glass surface first.

(2) Diffraction efficiency (η) measurement

Holographic recording is performed through the interference of two interfering lights (reference light and object light), and in transmission type recording, two beams are incident on the same side of the sample. The diffraction efficiency changes according to the incident angle of the two beams, and when the incident angles of the two beams are the same, the diffraction efficiency becomes non-slanted. In non-slanted recording, since the incidence angles of the two beams are the same based on the normal line, the diffraction pattern is generated perpendicular to the film.

Recording was performed in a transmission-type non-slanted method (2θ=45°) using a laser having a wavelength of 532 nm, and the diffraction efficiency (η) was calculated by the following general formula 1.

[General Formula 1]

In General Formula 1, η is the diffraction efficiency, P _D is the output amount of the diffracted beam of the sample after recording (mW/cm 2 ), and P _T is the output amount of the transmitted beam of the recorded sample (mW/cm 2 ).

(3) Refractive index modulation value (△n) measurement

For the lossless dielectric grating of the transmission hologram, the refractive index modulation value (Δn) can be calculated from General Formula 2 below.

[General Formula 2]

In General Formula 2, d is the thickness of the photopolymer layer, Δn is the refractive index modulation value, η (DE) is the diffraction efficiency, and λ is the recording wavelength.

Example photopolymer composition (unit: g) (Meth)acrylate-based copolymer (content:g) Polyol-1 Polyol-2 EG-diamine Aziridine hardener HR6042 Safranine O CN-386 Irgacure 250 TBP MIBK Example 1 Manufacturing Example 1 (7.5) 37.7 9.4 4.9 3.7 2.5 5.7 29 Example 2 Preparation Example 1 (14.5) 29 9.4 4.9 3.7 2.5 5.7 30 Example 3 Manufacturing Example 3 (10.8) 39.7 10.6 5.5 4.2 2.5 6.4 20 Example 4 Manufacturing Example 4 (13) 26.2 8.5 4.9 3.7 2.5 7.5 34 Example 5 Preparation Example 1 (8.7) 35.9 9.4 4.9 3.7 2.5 5.7 29 Example 6 Manufacturing Example 2 (10.1) 26.4 9.4 4.9 3.7 2.5 5.7 30 Example 7 Manufacturing Example 3 (12.6) 37.2 10.6 5.5 4.2 2.5 6.4 20 Example 8 Preparation Example 4 (14.8) 24 8.5 4.9 3.7 2.5 7.5 34 Example 9 Preparation Example 4 (14.8) 30.2 9.7 4.9 3.7 2.5 7.5 34 Example 10 Preparation Example 4 (14.8) 14.1 6.5 4.9 3.7 2.5 7.5 34

Experimental example measurement results of the holographic recording medium prepared from Diffraction efficiency (η) (%) Refractive index modulation value (△n) Example 1 53 0.009 Example 2 72 0.011 Example 3 75 0.011 Example 4 85 0.012 Example 5 55 0.009 Example 6 65 0.01 Example 7 77 0.011 Example 8 88 0.013 Example 9 89 0.013 Example 10 70 0.01

As shown in Tables 1 and 2, the photopolymer coating film of the obtained example using the (meth)acrylate-based copolymer prepared in Preparation Examples 1 to 3 has a refractive index modulation value (Δn) of 0.009 or more and 50 It was confirmed that a diffraction efficiency of% or more was shown.

In particular, the photopolymer coating films of Examples 3 and 7 using the (meth)acrylate-based copolymer of Preparation Example 3 have a refractive index modulation value (Δn) of 0.011 or more and can implement a diffraction efficiency of 70% or more, Preparation Example It was confirmed that the photopolymer coating films of Examples 4, 8 and 9 using the (meth)acrylate-based copolymer of 4 have a refractive index modulation value (Δn) of 0.012 or more and can implement a diffraction efficiency of 80% or more.

Accordingly, it was confirmed that the photopolymer coating film provided in the examples can implement a significantly improved refractive index modulation value and high diffraction efficiency while having a thin thickness.

Claims (14)

A repeating unit derived from alkenedioic acid or an anhydride thereof having 4 to 10 carbon atoms; And an alkyl acrylate repeating unit having 1 to 10 carbon atoms, and having a glass transition temperature of -40°C to 10°C (meth)acrylate-based (co)polymer;
Crosslinking agents including reactive functional groups;
Photoreactive monomers; And
A photopolymer composition for holographic recording comprising a photoinitiator.
The method of claim 1,
The (meth)acrylate-based (co)polymer comprises 1 to 40% by weight of repeating units derived from alkenedioic acid or an anhydride thereof having 4 to 10 carbon atoms, a photopolymer composition for holographic recording.
The method of claim 1,
The (meth)acrylate-based (co)polymer comprises a (co)polymer including a maleic anhydride repeating unit and an alkyl acrylate repeating unit having 1 to 10 carbon atoms, a photopolymer composition for holographic recording.
The method of claim 1,
The (meth)acrylate-based (co)polymer has a weight average molecular weight of 100,000 to 1,000,000, a photopolymer composition for holographic recording.
The method of claim 1,
The repeating unit derived from alkenedioic acid or an anhydride thereof having 4 to 10 carbon atoms includes a repeating unit derived from maleic anhydride,
An equivalent weight of maleic anhydride of the (meth)acrylate-based (co)polymer is 100 to 3,000 g/mol, a photopolymer composition for holographic recording.
The method of claim 1,
The crosslinking agent including the reactive functional group includes a compound containing at least one reactive functional group selected from the group consisting of a hydroxy group, a carboxyl group, an amine group, a thiol group, an epoxy group, an acyl halide, oxazoline, carbodiimide, and isocyanate, holographic Recording photopolymer composition.
The method of claim 1,
The crosslinking agent including the reactive functional group is a polyol, an ethylline glycol diamine, a polyfunctional aziridine curing agent, a polyfunctional thiol curing agent, or a polyfunctional epoxy curing agent, a photopolymer composition for holographic recording.
The method of claim 1,
The photoreactive monomer includes a polyfunctional (meth)acrylate monomer, or a monofunctional (meth)acrylate monomer, a photopolymer composition for holographic recording.
The method of claim 1,
A photopolymer composition for holographic recording, wherein the photoreactive monomer has a refractive index of 1.5 or more.
The method of claim 1,
1% to 80% by weight of the (meth)acrylate-based (co)polymer;
5 to 80% by weight of a crosslinking agent including the reactive functional group
5% to 80% by weight of the photoreactive monomer; And
0.1% to 15% by weight of the photoinitiator; containing, a photopolymer composition for holographic recording.
The method of claim 1,
The photopolymer composition further comprises at least one additive selected from the group consisting of a photosensitive dye, a plasticizer, and an antifoaming agent, a photopolymer composition for holographic recording.
A holographic recording medium prepared from the photopolymer composition for holographic recording of claim 1.
An optical element comprising the holographic recording medium of claim 12.
A holographic recording method comprising the step of selectively polymerizing the photoreactive monomer contained in the photopolymer composition for holographic recording of claim 1 by a coherent light source.