KR102106544B1 - Photopolymer composition - Google Patents

Abstract

The present invention is to provide a photopolymer composition capable of more easily providing a photopolymer layer having a high refractive index modulation value and improved durability against temperature and humidity, a hologram recording medium, an optical device, and a holographic recording method using the same will be.

Description

Photopolymer composition {PHOTOPOLYMER COMPOSITION}

The present invention relates to photopolymer compositions, holographic recording media, optical elements, and holographic recording methods.

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 the information.

When a photopolymer (photosensitive resin, photopolymer) is used, the optical interference pattern can be easily stored as a hologram by photopolymerization of a low-molecular monomer, and thus an optical lens, a mirror, a deflecting mirror, a filter, a diffusing screen, a diffractive member, a light guide, and a waveguide , 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, an optical wavelength divider, a reflective type, a transmissive color filter, and the like.

Typically, the photopolymer composition for hologram production includes a polymer binder, a monomer, and a photoinitiator, and irradiates laser interference light on a photosensitive film prepared from such a composition to induce photopolymerization of a localized monomer.

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

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

The present invention is to provide a photopolymer composition capable of more easily providing a photopolymer layer having a high refractive index modulation value and improved durability against temperature and humidity.

In addition, the present invention is to provide a holographic recording medium including a photopolymer layer with improved durability against temperature and humidity while having a large refractive index modulation value.

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

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

In the present specification, (i) a polymer matrix containing a reaction product between a (meth) acrylate-based (co) polymer in which the carboxyl group is located in a branched chain and (ii) a linear oxyalkylene diamine compound or a precursor thereof; Photoreactive monomers; And a photoinitiator; and a photopolymer composition having an amino group equivalent ratio of 0.5 to 2.0 in the linear oxyalkylene diamine compound compared to the carboxyl group equivalent contained in the (meth) acrylate-based (co) polymer is provided.

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

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

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

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

In the present specification, (meth) acrylate means methacrylate or acrylate.

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

In addition, in this specification, a hologram (hologram) refers to a recording medium in 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"), dennisyuk hologram, biaxial reflective hologram, edge-literature ( edge-literature) and includes holograms such as holograms or hologram stereograms.

In the present specification, the alkyl group may be straight chain or branched chain, and carbon number 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 are 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, cyclohexylmethyl, 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 is not limited thereto.

In the present specification, the alkylene group is a divalent functional group derived from alkane (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, tert-butylene group, pentylene group, hexylene group, or the like.

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

According to an embodiment of the present invention, (i) a polymer matrix or a precursor thereof comprising a reaction product between a (meth) acrylate-based (co) polymer in which the carboxyl group is located in a branched chain and (ii) a linear oxyalkylene diamine compound; Photoreactive monomers; And a photoinitiator, and a photopolymer composition having an amino group equivalent ratio of 0.5 to 2.0 contained in the linear oxyalkylene diamine compound compared to the carboxyl group equivalent contained in the (meth) acrylate-based (co) polymer may be provided. .

The present inventors have a thinner hologram formed from a photopolymer composition comprising a polymer matrix using a reaction product between a (meth) acrylate-based (co) polymer in which the carboxyl group is located in a branched chain and a linear oxyalkylene diamine compound. Even in the experiment, it was confirmed through experiments that a significantly improved refractive index modulation value and excellent temperature and humidity durability can be realized compared to a previously known hologram.

More specifically, the product obtained by reacting a linear oxyalkylene diamine compound capable of forming an amide crosslink by reacting with a carboxyl group located in the branched chain of the (meth) acrylate-based (co) polymer is applied as a polymer matrix. Accordingly, the polymer matrix can be easily cured by simply applying heat without adding a catalyst.

In particular, the linear oxyalkylene diamine compound comprises a main chain including a dioxyalkylene group and an amino group bound to the sock end of the main chain, while the linear relative to the carboxyl group equivalent in the (meth) acrylate-based (co) polymer As the amino group equivalent ratio contained in the oxyalkylene diamine compound of 0.5 satisfies 0.5 to 2.0, the volume shrinkage can be minimized during hologram recording due to the high crosslinking effect, and the oxygen atom maintains compatibility with other constituents. The recording characteristics can be improved by maximizing the refractive index modulation. In addition, the crosslinking density between the (meth) acrylate-based (co) polymer and the linear oxyalkylene diamine compound is optimized, thereby ensuring excellent durability compared to the existing matrix.

On the other hand, if the oxyalkylene structure is not included as the main chain as in the above embodiment, compatibility problems may occur due to the properties of the compound having many polar molecules, and the weight average molecular weight (GPC measurement) of the diamine compound increases to more than 150 If it does, there may be a problem that the diffraction efficiency decreases.

In addition, the present invention may further include a fluorine-based compound or a phosphate-based compound as a component of the polymer matrix or a precursor thereof, and the fluorine-based compound or phosphate-based compound has a lower refractive index than the photoreactive monomer, thereby The refractive index can be lowered to maximize the modulation of the refractive index of the photopolymer composition.

Moreover, the phosphate-based compound acts as a plasticizer, thereby lowering the glass transition temperature of the polymer matrix to increase the moldability of the photopolymer composition or facilitate the movement of monomers.

Hereinafter, each component of the photopolymer composition of the embodiment will be described in more detail.

(1) Polymer matrix or precursor thereof

The polymer matrix may serve as a support for a final product such as the photopolymer composition and a film prepared therefrom, and may serve to increase the refractive index modulation as a portion having a different refractive index in the hologram formed from the photopolymer composition.

As described above, the polymer matrix may include a reaction product between (i) a (meth) acrylate-based (co) polymer in which the carboxyl group is located in a branched chain, and (ii) a linear oxyalkylene diamine compound. Accordingly, the precursor of the polymer matrix includes a monomer or oligomer forming the polymer matrix, specifically, a (meth) acrylate-based (co) polymer in which the carboxyl group is located in a branched chain, or a monomer thereof or an oligomer of the monomer , And a linear oxyalkylene diamine compound, or a monomer thereof or an oligomer of the monomer.

Meanwhile, the linear oxyalkylene diamine compound may be a compound having two amino groups per molecule or a mixture thereof. The amino group forms an amide bond through an amide reaction with the carboxyl group included in the (meth) acrylate-based (co) polymer to crosslink the linear (oxyalkylene diamine) compound with the (meth) acrylate-based (co) polymer. You can.

At this time, the polymer matrix or a precursor thereof may have an equivalent of the amino group of 200 g / piece to 3000 g / piece, or 500 g / piece to 3000 g / piece. The equivalent weight refers to the average molecular weight of the acrylate-based copolymer forming a matrix occupied per functional group, the smaller the equivalent value, the higher the density of the functional group, and the larger the equivalent value, the smaller the functional group density. The example of the method for measuring the equivalent is not particularly limited, but for example, for quantitative analysis, it can be measured by nuclear magnetic resonance method and indirectly observe the change in the glass transition temperature through DSC analysis. .

Accordingly, the crosslink density between the (meth) acrylate-based (co) polymer and the linear oxyalkylene diamine compound is optimized, and thus excellent durability compared to the existing matrix can be secured. In addition, by optimizing the crosslinking density described above, by increasing the mobility between the photoreactive monomer having a high refractive index and a component having a low refractive index, the modulation of the refractive index can be maximized to improve the recording characteristics.

When the equivalent amount of the amino group contained in the polymer matrix or precursor thereof is excessively reduced to less than 200 g / piece or excessively increased to more than 3000 g / piece, the ratio of carboxyl group and amino group is misaligned, so that curing of the film does not occur smoothly Can occur.

More specifically, the linear oxyalkylene diamine compound may include a main chain including a dioxyalkylene group and an amino group bound to the sock end of the main chain.

The dioxyalkylene group may include a functional group represented by Formula 1 below.

[Formula 1]

In Formula 1, R ₁ to R ₃ are each independently an alkylene group having 1 to 5 carbon atoms. Preferably, in Formula 1, R ₁ to R ₃ may each independently be an ethylene group having 2 carbon atoms, which may be derived from 2,2- (ethylenedioxy) bis (ethylamine).

Accordingly, when the oxyalkylene structure is included as the main chain, as in the one embodiment, an effect of increasing the compatibility of other components can be realized. On the other hand, if the oxyalkylene structure is not included as the main chain, as in the above-described one embodiment, compatibility problems may occur, and selection and addition of components may be difficult.

The oxyalkylene diamine compound may have a weight average molecular weight (GPC measurement) of 150 or less, or 100 to 150, or 130 to 150, or 140 to 150. The weight average molecular weight means the weight average molecular weight (unit: g / mol) of polystyrene conversion measured by GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, detectors and analytical columns, such as a commonly known analytical device and a differential index detector, can be used, and the temperature is usually applied. Conditions, solvents and flow rates can be applied. Specific examples of the measurement conditions include a temperature of 30 ° C, a chloroform solvent (Chloroform) and a flow rate of 1 mL / min. When the weight average molecular weight (GPC measurement) of the oxyalkylene diamine compound increases to more than 150, a reduction in diffraction efficiency may occur.

In the (meth) acrylate-based (co) polymer, a carboxyl group may be located in the branched chain. The carboxyl group is a functional group represented by -COOH, and may bind to the end of a branched chain extending from the polyethylene-based main chain of the (meth) acrylate-based (co) polymer.

The carboxyl group can crosslink the (meth) acrylate-based (co) polymer and the linear oxyalkylene diamine compound by forming an amide bond through an amidation reaction with the amino group contained in the linear oxyalkylene diamine compound. .

In this case, the (meth) acrylate-based (co) polymer has an equivalent weight of the carboxyl group of 300 g / piece to 3000 g / piece, or 500 g / piece to 2000 g / piece, or 600 g / piece to 1800 g / piece , Or 650 g / piece to 1600 g / piece, or 700 g / piece to 1450 g / piece. The equivalent weight refers to the molecular weight occupied per functional group, the smaller the equivalent value, the higher the density of the functional group, and the larger the equivalent value, the smaller the functional group density.

Accordingly, the crosslinking density between the (meth) acrylate-based (co) polymer and the linear oxyalkylene diamine compound is optimized, thereby ensuring excellent durability against temperature and humidity compared to the existing matrix. In addition, by optimizing the crosslinking density described above, by increasing the mobility between the photoreactive monomer having a high refractive index and a component having a low refractive index, the modulation of the refractive index can be maximized to improve the recording characteristics.

When the equivalent amount of the carboxyl group included in the (meth) acrylate-based (co) polymer is excessively reduced to less than 300 g / piece, the hardness of the film increases, and a problem that mechanical properties may be weakened may occur. When the equivalent amount of the carboxyl group contained in the meth) acrylate-based (co) polymer is excessively increased to more than 3000 g / piece, the network structure in the matrix is difficult to form tightly, and the hardening is poor and the durability of the film is reduced or the refractive index A problem in which modulation values and diffraction efficiency are greatly reduced may occur.

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

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

[Formula 2]

In Chemical 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 hydrogen, a repeating unit derived from acrylic acid.

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

[Formula 3]

In Chemical 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 Chemical Formula 2, R ₅ is a butyl group having 4 carbon atoms or a methyl group having 1 carbon atoms. , And R ₆ may be hydrogen, a repeating unit derived from butyl acrylate or methyl acrylate.

The molar ratio between the repeating units of Chemical Formula 1 and the repeating units of Chemical Formula 2 may be 1: 1 to 1: 1. When the molar ratio of the repeating unit of Formula 1 is excessively reduced, the degree of crosslinking in the polymer matrix may drop excessively, and when the molar ratio of the repeating unit of Formula 1 is excessively increased, a phenomenon of excessively high hardness may occur.

The (meth) acrylate-based (co) polymer may have a weight average molecular weight (GPC measurement) of 200,000 to 5,000,000, or 500,000 to 1,000,000. The weight average molecular weight means the weight average molecular weight (unit: g / mol) of polystyrene conversion measured by GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, detectors and analytical columns, such as a commonly known analytical device and a differential index detector, can be used, and the temperature is usually applied. Conditions, solvents and flow rates can be applied. Specific examples of the measurement conditions include a temperature of 30 ° C, a chloroform solvent (Chloroform) and a flow rate of 1 mL / min.

Meanwhile, in the reaction product between (i) a (meth) acrylate-based (co) polymer in which the carboxyl group is located in a branched chain and (ii) a linear oxyalkylene diamine compound, the (meth) acrylate-based (co) polymer 100 With respect to parts by weight, the content of the linear oxyalkylene diamine compound is 0.1 parts by weight to 30 parts by weight, or 1 part by weight to 20 parts by weight, or 5 parts by weight to 30 parts by weight, or 5 parts by weight to 15 parts by weight You can.

In the reaction product, when the content of the linear oxyalkylene diamine compound is excessively reduced or increased, based on 100 parts by weight of the (meth) acrylate-based (co) polymer, mechanical properties and diffraction characteristics are optimized in the polymer matrix. It can be difficult to achieve a sufficient level of crosslinking.

Meanwhile, the polymer matrix may include (i) a (meth) acrylate-based (co) polymer in which the carboxyl group is located in a branched chain, and (ii) a polymer resin in which a linear oxyalkylene diamine compound is bonded via a urethane bond. have. Specifically, the (meth) acrylate-based (co) polymer in which the carboxyl group is located in the branched chain is bonded to one end of the urethane bond, and the linear oxyalkylene diamine compound is bonded to the other end of the urethane bond, thereby urethane bond This carboxyl group can mediate the bond between the (meth) acrylate-based (co) polymer located in the branched chain and the linear oxyalkylene diamine compound.

On the other hand, in the polymer matrix or precursor thereof, the ratio of the amino group equivalent in the linear oxyalkylene diamine compound to the equivalent of the carboxyl group in the (meth) acrylate-based (co) polymer is 0.5 to 2.0, or 0.7 to 1.7 Or 1.0 to 1.4. The ratio of the amino group equivalent to the equivalent of the carboxyl group means a value obtained by dividing the equivalent of the amino group contained in the polymer matrix or precursor thereof by the equivalent of the carboxyl group.

In the polymer matrix or a precursor thereof, the crosslink density between the (meth) acrylate-based (co) polymer and the linear oxyalkylene diamine compound is optimized as the ratio of the amino group equivalent to the carboxyl group equivalent satisfies the above range, It can secure excellent durability against temperature and humidity compared to the existing matrix. In addition, by optimizing the crosslinking density described above, by increasing the mobility between the photoreactive monomer having a high refractive index and a component having a low refractive index, the modulation of the refractive index can be maximized to improve the recording characteristics.

In the polymer matrix or its precursor, the ratio of the amino group equivalent in the linear oxyalkylene diamine compound to the equivalent of the carboxyl group contained in the (meth) acrylate-based (co) polymer is reduced to less than 0.5, or increased to more than 2.0 If there is, there is a technical limit in which the refractive index modulation value (n) and the diffraction efficiency are reduced to about 10 times.

In addition, the modulus (tensile) of the reaction product may be 1 (GPa) to 20 (GPa). As a specific example of the method of measuring the modulus, a method of measuring a specimen by cutting it to a size of 1 cm and pulling it from both sides may be used.

In addition, the modulus (storage modulus) of the reaction product may be 0.01 MPa to 5 MPa. As a specific example of the modulus measurement method, a storage modulus (G ′) value may be measured at a frequency of 1 Hz at room temperature (20 ° C. to 25 ° C.) using TA Instruments' discovery hybrid rheometer (DHR) equipment.

The glass transition temperature (DSC measurement) of the reaction product may be -40 ℃ to 20 ℃. As a specific example of the method for measuring the glass transition temperature, a photopolymerization composition is coated in a region of -80 ° C to 30 ° C under a setting condition of strain 0.1%, frequency 1Hz, heating rate 5 ° C / min using a DMA (dynamic mechanical analysis) measurement equipment. And measuring the change in phase angle (Loss modulus) of the film.

(2) Photoreactive monomer

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 the polymer is relatively high, and the refractive index is relatively lower in the portion where the polymer binder is relatively high, resulting in modulation of the refractive index. , 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 a compound containing a vinyl group or a thiol group.

An example of the photoreactive monomer includes 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 the 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 polyfunctional (meth) acrylate monomer having a refractive index of 1.5 or more are sphenol A modified diacrylate series, fluorene acrylate series (HR6022, etc.-Miwon), bisphenol fluorene epoxy acrylate series (HR6100, HR6060, HR6042, etc.)-Miwon ), Halogenated epoxy acrylate (HR1139, HR3362, etc.-Miwon).

Another example of the photoreactive monomer is a monofunctional (meth) acrylate monomer. The monofunctional (meth) acrylate monomer may include an ether bond and a fluorene functional group inside the molecule, and specific examples of such monofunctional (meth) acrylate monomers include phenoxy benzyl (meth) acrylate and o-phenyl And 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 means the weight average molecular weight in terms of polystyrene measured by the GPC method.

 (3) Photoinitiator

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 can be used without great limitation, but specific examples thereof include a photo radical polymerization initiator, a photocationic polymerization initiator, or a photoanionic polymerization initiator.

Specific examples of the photo-radical polymerization initiator, imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocenes, aluminate complexes, organic peroxides, N-alkoxy pyridinium salts, thioxanthone Derivatives, amine derivatives, and the like. More specifically, the photo-radical polymerization initiators 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: 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, for example, sulfonic acid ester, imide sulfonate, dialkyl-4 -Hydroxy sulfonium salt, aryl sulfonic acid-p-nitro benzyl ester, silanol-aluminum complex, (η6-benzene) (η5-cyclopentadienyl) iron (II), and the like. Moreover, benzoin tosylate, 2,5-dinitro benzyl tosylate, N-tosylphthalic acid imide, etc. 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 And commercially available products such as (manufacturer: Nippon Soda).

A borate salt is mentioned as said photoanionic polymerization initiator, For example, butyryl chlorine butyl triphenyl borate (BUTYRYL CHOLINE BUTYLTRIPHENYLBORATE) etc. are mentioned. More specific examples of the photoanionic polymerization initiator include commercial products such as Borate V (manufacturer: Spectra group).

In addition, the photopolymer composition of the above embodiment may use a monomolecular (type I) or bimolecular (type II) initiator. The (Type I) system for free radical photopolymerization is, for example, aromatic ketone compounds combined with tertiary amines, such as benzophenone, alkylbenzophenone, 4,4'-bis (dimethylamino) benzophenone (Michler's ) Ketone), anthrone and halogenated benzophenone or mixtures of this type. The bimolecular (type II) initiators include benzoin and its derivatives, benzyl ketal, acylphosphine oxide, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bisacylphosphine oxide, phenylglyce Oxyl ester, campoquinone, alpha-aminoalkylphenone, alpha-, alpha-dialkoxyacetophenone, 1- [4- (phenylthio) phenyl] octane-1,2-dione 2- (O-benzoyloxime) and alpha -Hydroxyalkyl phenone, etc. are mentioned.

 (4) Photopolymer composition

The photopolymer composition is 20 to 80% by weight of the polymer matrix or a precursor thereof; 10 to 70% by weight of the photoreactive monomer; And photoinitiator 0.1 to 15% by weight; may include, as described below, when the photopolymer composition further comprises an organic solvent, the content of the above-described components are the sum of these components (the sum of components excluding organic solvents) ).

The photopolymer composition may further include a fluorine-based compound. Since the fluorine-based compound has stability with little reactivity, and has low refractive index characteristics, when added to the photopolymer composition, the refractive index of the polymer matrix can be lowered, thereby maximizing the modulation of the refractive index with the monomer.

The fluorine-based compound may include at least one functional group and at least two difluoromethylene groups selected from the group consisting of ether groups, ester groups and amide groups. More specifically, the fluorine-based compound may have the following Formula 4 structure in which a functional group containing an ether group is bonded to the sock end of a central functional group including a direct bond or an ether bond of two difluoromethylene periods.

[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, 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 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 more than 1.4 and less than 1.45. Since the photoreactive monomer has a refractive index of 1.5 or more as described above, the fluorine-based compound can lower the refractive index of the polymer matrix through a lower refractive index than the photoreactive monomer, thereby maximizing the refractive index modulation 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.

When the content of the fluorine-based compound is excessively reduced with respect to 100 parts by weight of the photoreactive monomer, the modulation value of the refractive index after recording is lowered due to the lack of the 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. When the crosslinking degree is low, the film may not be formed or the compatibility may be poor, resulting in a high defect rate, and a haze may occur due to compatibility problems with other components or a problem in which some fluorine-based compounds elute 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. The 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 increases or decreases the photoinitiator. More specifically, the photosensitive dye is also stimulated by light irradiated to the photopolymer composition, and also serves as an initiator for initiating polymerization of monomers and crosslinking monomers. can do. The photopolymer composition may include 0.01 to 30% by weight of a photosensitive dye, or 0.05 to 20% by weight.

Examples of the photosensitive dye are not particularly limited, and various commonly known compounds may be used. Specific examples of the photosensitive dyes, sulfonium derivatives of ceramidonin, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylcera Midosine (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 (crystal violet), Brilliant Green, Astrazon orange G, darrow red, pyronin Y, basic red 29, pyryllium I (pyrylium iodide), Safranin O, Cyanine, Methyl Blue, can be given a very Le A (Azure A), or a combination of two or more.

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 organic solvents include ketones such as methyl ethyl kenone, methyl isobutyl ketone, acetyl acetone 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 mixtures of two or more of these.

The organic solvent may be added at the time of mixing each component included in the photopolymer composition or may be included in the photopolymer composition while each component is added in a dispersed or mixed state to the organic solvent. If the content of the organic solvent in the photopolymer composition is too small, the flowability of the photopolymer composition is lowered, and defects such as streaks may occur in the final film. In addition, when the excess amount of the organic solvent is added, the solid content is lowered, coating and film formation are insufficient, and thus the physical properties or surface properties of the film may be deteriorated, and defects may occur in the drying and curing process. 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 include a catalyst commonly known to promote polymerization of the polymer matrix or photoreactive monomer. Examples of the catalyst include tin octanoate, zinc octanoate, dibutyltin dilaurate, dimethylbis [(1-oxoneodecyl) oxy] stanan, dimethyltin dicarboxylate, zirconium bis (ethylhexa Noate), zirconium acetylacetonate, p-toluenesulfonic acid or tertiary amines, such as 1,4-diazabicycl [2.2.2] octane, diazabiclononan, diazabicyclonedecane , 1,1,3,3-tetramethylguanidine, 1,3,4,6,7,8-hexahydro-1-methyl-2H-pyrimidido (1,2-a) pyrimidine. . Examples of the other additives include an antifoaming agent or a phosphate plasticizer, and as the antifoaming agent, a silicone-based reactive additive may be used, 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 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.

The photopolymer composition may be used for hologram recording.

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

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

The hologram recording medium can implement a refractive index modulation value (n) of 0.009 or more or 0.010 or more even at a thickness of 5 μm to 30 μm.

In addition, the hologram recording medium can realize a diffraction efficiency of 50% or more or 85% or more at a thickness of 5 μm to 30 μm.

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

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

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

On the other hand, after homogenizing and mixing a component forming a polymer matrix or a precursor thereof among the photopolymer composition of the embodiment, the photopolymer composition at the time of adding the linear silane crosslinking agent has a liquid formulation that is cured at a temperature of 20 ° C. or higher. Can be.

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

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

Meanwhile, a method of recording a visual hologram on a hologram recording medium prepared from the photopolymer composition can use a conventionally known method without great limitation, and the method described in the holographic recording method of an embodiment described later may be used as an example. You can.

Meanwhile, according to another embodiment of the present invention, a holographic recording method may be provided that includes 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 manufactured through a process of mixing and curing the photopolymer composition, and a visual hologram may be recorded on the medium through a predetermined exposure process.

In the medium provided through the process of mixing and curing the photopolymer composition, a visual hologram may be recorded using a known device 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 elements include optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, diffractive elements, light guides, waveguides, projection screens and / or holographic optical elements having the function of masks, media and light in optical memory systems Diffusion plates, optical wavelength dividers, reflective, transmissive color filters, and the like.

An example of an optical element including the hologram recording medium 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 portion that irradiates a laser beam used to provide, record, and reproduce 3D image information of an object in an input unit and a display unit. In addition, the input unit is a portion for inputting 3D image information of an object to be recorded in the display unit in advance. Dimensional information can be entered, where 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., the optical system is an input beam that sends a laser beam emitted from the light source unit to the input unit, a recording beam to the display unit, a reference beam, an erasing beam, a poison It can be distributed by exit beam, etc.

The display unit receives the 3D image information of the object from the input unit, records it on a hologram plate made of an optically driven optically addressed SLM (SLM), and reproduces the 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 can be reproduced as a 3D image by the diffraction pattern generated by the read beam, and the erase beam can be used to quickly remove the formed diffraction pattern. On the other hand, the hologram plate may be moved between a position for inputting a 3D image and a position for reproduction.

According to the present invention, a photopolymer composition capable of more easily providing a photopolymer layer having a high refractive index modulation value and improved durability against temperature and humidity, a hologram recording medium, an optical element, and a holographic recording method using the same Can be.

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

[Production Example 1: Manufacturing method of acrylic copolymer]

In a 2L round flask, 75 g of ethyl acetate and 17 g (85 wt%) of butyl acrylate as an acrylic monomer, 2 g (10 wt%) of methyl acrylate, and 1 g (5 wt%) of acrylic acid were added and purged with nitrogen while stirring for 30 minutes. The reaction temperature was set at 70 ° C in an oil bath, 0.01 g of n-dodecyl mercaptan and 0.01 g of AIBN as a polymerization initiator were added, and polymerization was performed for 6 hours to obtain an acrylic copolymer (weight average molecular weight Mw = 2,000,000, carboxy group ( -COOH) equivalent = 1441.2 g / piece).

[Production Example 2: Manufacturing method of acrylic copolymer]

In a 2L round flask, 75 g of ethyl acetate and 18 g (90 wt%) of butyl acrylate as an acrylic monomer and 2 g (10 wt%) of acrylic acid were added and purged with nitrogen while stirring for 30 minutes. The reaction temperature was set at 70 ° C. in an oil bath, 0.01 g of n-dodecyl mercaptan and 0.01 g of AIBN as a polymerization initiator were added, and polymerization was performed for 6 hours to obtain an acrylic copolymer (weight average molecular weight Mw = 500,000, carboxy group ( -COOH) equivalent = 720.6 g / piece).

[Production Example 3: Method for manufacturing non-reactive low refractive material]

Add 20.51 g of 2,2 '-((oxybis (1,1,2,2-tetrafluoroethane-2,1-diyl)) bis (oxy)) bis (2,2-difluoroethan-1-ol) to a 1000 ml flask Subsequently, 4.40 g of sodium hydride (60% dispersion in mineral oil) was carefully added over several times while dissolving in 500 g of tetrahydrofuran and stirring at 0 ° C. After stirring at 0 ° C for 20 minutes, 12.50 ml of 2-methoxyethoxymethyl chloride was slowly dropped. When it was confirmed that all the reactants were consumed by ¹ H NMR, the reaction solvent was removed under reduced pressure. After extracting three times with dichloromethane 300g, the organic layers were collected, filtered with magnesium sulfate, and then dichloromethane was removed under reduced pressure to obtain 29 g of a liquid product having a purity of 95% or higher with a yield of 98%.

[Comparative Production Example 1: Manufacturing method of acrylic copolymer]

In a 2L round flask, 75 g of ethyl acetate and 19.6 g (98 wt%) of butyl acrylate as an acrylic monomer and 0.5 g (2 wt%) of acrylic acid were added and purged with nitrogen while stirring for 30 minutes. The reaction temperature was set at 70 ° C. in an oil bath, 0.01 g of n-dodecyl mercaptan and 0.01 g of AIBN as a polymerization initiator were added, and polymerization was performed for 6 hours to obtain an acrylic copolymer (weight average molecular weight Mw = 500,000, carboxy group ( -COOH) equivalent = 3600 g / piece).

[Comparative Production Example 2: Manufacturing method of acrylic copolymer]

In a 2L round flask, 75 g of ethyl acetate and 13 g (65% by weight) of butyl acrylate as an acrylic monomer and 7 g (35% by weight) of acrylic acid were added and purged with nitrogen while stirring for 30 minutes. The reaction temperature was set at 70 ° C. in an oil bath, 0.01 g of n-dodecyl mercaptan and 0.01 g of AIBN as a polymerization initiator were added, and polymerization was performed for 6 hours to obtain an acrylic copolymer (weight average molecular weight Mw = 500,000, carboxy group ( -COOH) equivalent = 200 g / piece).

[Examples and Comparative Examples: Preparation of Photopolymer Composition]

As shown in Table 1 or Table 2 below, the acrylic copolymers obtained in Preparation Examples 1 to 2 or Comparative Preparation Examples 1 to 2, photoreactive monomers (high refractive acrylate, refractive index 1.600, HR6042 [Miwon]), safranin O ( Dye, Sigma Aldrich Co.), Borate V (Spectra group), H-Nu 254 (Radial photoinitiator, Spectra Group Limited product), non-reactive low refractive material of Preparation Example 3 and methylisobutyl ketone (MIBK) to block light The mixture was mixed in one state and stirred for 10 minutes with a Paste mixer to obtain a transparent coating solution.

Equivalent ratio (-NH ₂ / -COOH) of 2,2- (ethylenedioxy) bis (ethylamine) [2,2- (Ethylenedioxy) bis (ethylamine)] as the crosslinking agent in the coating solution is shown in Table 1 or Table 2 below. ) And further stirred for 5-10 minutes. Then, using a meyer bar, coated on a 80 μm thick TAC substrate, and dried at 60 ° C. for 1 hour.

[Experimental example: Holographic recording]

(1) The photopolymer coating surface prepared in each of the above Examples and Comparative Examples was laminated to a slide glass, and fixed so that the laser first passed through the glass surface during recording.

(2) Diffraction efficiency (η) measurement

The holographic is recorded through the interference of two interfering lights (reference light and object light), and the transmissive type records two beams incident on the same side of the sample. The diffraction efficiency varies depending on the incident angle of the two beams, and becomes non-slanted when the incident angles of the two beams are the same. In the non-slanted recording, since the angle of incidence of the two beams is the same on a normal basis, diffraction defects are generated perpendicular to the film.

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

[Formula 1]

In the above 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) Measurement of refractive index modulation value (△ n)

Lossless Dielectric grating of the transmissive hologram can calculate the refractive index modulation value (Δn) from the following general formula (2).

[Formula 2]

In the above 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.

(4) Measurement of I _loss

The laser loss amount (I _loss ) can be calculated from the following general formula (3).

[Formula 3]

I _loss = 1-{(P _D + P _T ) / I _O }

In the general formula 3, P _D is the output amount of the diffracted beam of the sample after recording (mW / cm 2), P _T is the output amount of the transmitted beam of the recorded sample (mW / cm 2), and I ₀ is the intensity of the recording light .

Experimental Example Measurement Results of Photopolymer Composition of Examples and Holographic Recording Media Prepared From division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Compound used Preparation Example 1
(Unit: g) 0.318 0.318 0.318 - - - Preparation Example 2
(Unit: g) - - - 0.2 0.2 0.2 Crosslinker
(Unit: g) 0.0165 0.0195 0.0228 0.0207 0.0246 0.0288 HR6022
(Unit: g) 0.335 0.335 0.335 0.220 0.220 0.220 Safranine O
(Unit: g) 0.00125 0.00125 0.00125 0.0008 0.0008 0.0008 Borate V
(Unit: g) 0.0012 0.0012 0.0012 0.0008 0.0008 0.0008 H-Nu 254
(Unit: g) 0.0012 0.0012 0.0012 0.0008 0.0008 0.0008 Preparation Example 3
(Unit: g) 0.350 0.350 0.350 0.230 0.230 0.230 MIBK
(Unit: g) 4 4 4 3 3 3 Coating thickness (unit: μm) 10 10 11 11 10 11 -NH ₂ equivalent / -COOH equivalent 1.0 1.2 1.4 1.0 1.2 1.4 Diffraction efficiency (η) (%) 88 85 90 93 86 90 Refractive index modulation value (n) 0.0191 0.0185 0.0175 0.0186 0.0187 0.0177 Laser loss (I _loss ) (%) 28 30 34 30 30 28

Experimental Example Measurement Results of Photopolymer Composition of Comparative Example and Holographic Recording Media Prepared From It division Comparative Example 1 Comparative Example 2 Comparative Example 3 Compound used Preparation Example 1
(Unit: g) One One - Comparative Production Example 1
(Unit: g) - - - Comparative Production Example 2
(Unit: g) - - - Urethane polymer
(Unit: g) - - 2 MFA-75X
(Unit: g) - - 0.0732 Crosslinker
(Unit: g) 0.0819 0.0027 - TBP
(Unit: g) - - 0.138 HR6042
(Unit: g) 0.612 0.532 0.473 Safranine O
(Unit: g) 0.00125 0.00125 0.00145 Ebecryl P-115
(Unit: g) - - 0.069 Borate V
(Unit: g) 0.0012 0.0012 - Preparation Example 3
(Unit: g) 0.350 0.350 0.138 H-Nu 254
(Unit: g) 0.0012 0.0012 0.0041 MIBK
(Unit: g) 4 4 3 Coating thickness (unit: μm) 10 10 10 -NH ₂ equivalent / -COOH equivalent 3.0 0.1 1.1 Diffraction efficiency (η) (%) below 10 below 10 78 Refractive index modulation value (n) 0.005 or less 0.005 or less 0.0168 Laser loss (I _loss ) (%) 27 30 32

* MFA-75X: Isocyanate curing agent, Asahikaze

* TBP: Tributyl phosphate (Tributyl phosphate, molecular weight 266.31, refractive index 1.424, manufactured by Sigma Aldrich)

* Ebecryl P-115: SK entis

As shown in Table 1 and Table 2, in the case of the photopolymer composition of the embodiment using a crosslinking agent having an amino group equivalent ratio of 0.5 to 2.0 with respect to the carboxyl group equivalent of the polymers prepared in Preparation Examples 1 to 2, the amino group equivalent ratio is 3.0 Phosphorus Comparative Example 1, while showing an equivalent level of laser loss compared to Comparative Example 2 with an amino group equivalent ratio of 0.1, significantly improved refractive index modulation value (n), and provides an excellent hologram with high diffraction efficiency of 85% or higher. Was confirmed.

On the other hand, in the case of the photopolymer composition of Comparative Example 3 in which the urethane polymer was used as a polymer matrix, the refractive index modulation value (n) was measured to be 0.0168 and decreased compared to the example of 0.0175 or more, and the diffraction efficiency was 78%. It was confirmed that it was also reduced compared to the example of more than%.

Claims (19)

(i) a polymer matrix or a precursor thereof comprising a reaction product between a (meth) acrylate-based (co) polymer in which the carboxyl group is located on a branched chain and (ii) a linear oxyalkylene diamine compound;
Photoreactive monomers; And
Photoinitiator,
The photopolymer composition having an amino group equivalent ratio in the linear oxyalkylene diamine compound compared to the equivalent of the carboxyl group included in the (meth) acrylate-based (co) polymer is 0.5 to 2.0.
According to claim 1,
The equivalent of the carboxyl group is 300 g / piece to 3000 g / individual, photopolymer composition.
According to claim 1,
The photopolymer composition in which the content of the oxyalkylene diamine compound is 0.1 parts by weight to 30 parts by weight based on 100 parts by weight of the (meth) acrylate-based (co) polymer.
According to claim 1,
The photopolymer composition of modulus (tensile strength measurement method) of the reaction product is 1 (GPa) to 20 (GPa).
According to claim 1,
The modulus (storage modulus, G ') of the reaction product is 0.01 MPa to 5 MPa when measured at a frequency of 1 Hz at room temperature with DHR equipment (TA Instrument).
According to claim 1,
The linear oxyalkylene diamine compound comprises a main chain including a dioxyalkylene group and an amino group bound to the sock end of the main chain, a photopolymer composition.
The method of claim 6,
The dioxyalkylene group is represented by the following formula (1), photopolymer composition:
[Formula 1]

In Formula 1, R ₁ to R ₃ are each independently an alkylene group having 1 to 5 carbon atoms.
According to claim 1,
A photopolymer composition having a weight average molecular weight (GPC measurement) of 150 or less of the linear oxyalkylene diamine compound.
According to claim 1,
The equivalent of the amino group contained in the polymer matrix or precursor thereof is 200 g / piece to 3000 g / individual, photopolymer composition.
According to claim 1,
The photoreactive monomer comprises a polyfunctional (meth) acrylate monomer, or a monofunctional (meth) acrylate monomer, photopolymer composition.
According to claim 1,
A photopolymer composition having a refractive index of 1.5 or more of the photoreactive monomer.
According to claim 1,
20 to 80% by weight of the polymer matrix or a precursor thereof;
10 to 70% by weight of the photoreactive monomer; And
A photopolymer composition comprising; 0.1% to 15% by weight of a photoinitiator.
According to claim 1,
The photopolymer composition further comprises a fluorine-based compound, a photopolymer composition.
The method of claim 13,
The fluorine-based compound is a photopolymer composition comprising at least one functional group and at least two difluoromethylene groups selected from the group consisting of ether groups, ester groups and amide groups.
According to claim 1,
The polymer matrix has a refractive index of 1.5 or less, a photopolymer composition.
According to claim 1,
The photopolymer composition further comprises a photosensitive dye, a phosphate-based plasticizer, or an antifoaming agent.
A holographic recording medium prepared from the photopolymer composition of claim 1.
An optical element comprising the holographic recording medium of claim 17.
A method for holographic recording, comprising the step of selectively polymerizing a photoreactive monomer contained in the photopolymer composition of claim 1 with a coherent light source.