KR20230006301A - Photopolymer composition - Google Patents

Abstract

The present invention is to provide a photopolymer composition for forming hologram, which contains: a polymer matrix or a precursor thereof; photoreactive monomers; photoinitiators; and a compound having a predetermined structure; a hologram recording medium using the same; an optical element; and a holographic recording method.

Description

Photopolymer composition {PHOTOPOLYMER COMPOSITION}

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

A hologram recording medium records information by changing a refractive index in a holographic recording layer in the medium through an exposure process, and reproduces the information by reading the change in refractive index in the recorded medium.

When using a photopolymer (photopolymer), optical interference patterns can be easily stored as holograms by photopolymerization of low molecular weight monomers, so optical lenses, mirrors, deflecting mirrors, filters, diffusion screens, diffraction members, light guides, and waveguides , a holographic optical element having a function of a projection screen and/or mask, a medium of an optical memory system and an optical diffusion plate, an optical wavelength splitter, and a reflective and transmissive color filter.

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

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

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

An object of the present invention is to provide a photopolymer composition for forming a hologram that can more efficiently and easily provide a photopolymer layer capable of realizing a higher refractive index modulation value even in a thin thickness range.

In addition, the present invention is to provide a hologram recording medium including a photopolymer layer capable of implementing a higher refractive index modulation value even in a thin thickness range.

In addition, 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 the photoreactive monomer included in the photopolymer composition by a coherent laser.

In the present specification, a polymer matrix or a precursor thereof; photoreactive monomers; photoinitiators; And a compound represented by Formula 1; and a photopolymer composition for forming a hologram is provided.

[Formula 1]

In Formula 1,

R ₁ and R ₂ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 5 carbon atoms,

n and m are integers from 1 to 10;

R ₃ and R ₄ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 5 carbon atoms,

X ₁ and X ₂ may be the same as or different from each other, and are each independently a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms, or a functional group represented by Formula 2 below, and at least one of X ₁ and X ₂ is a functional group represented by Formula 2 below. to be.

[Formula 2]

In Formula 2, Y ₁ is a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,

Y ₂ is a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms, or a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms bonded to an alkoxy group, or a straight-chain bonded to a heterocyclic ring having 2 to 10 carbon atoms containing at least one oxygen. or a branched chain alkyl group.

Also, in the present specification, a hologram recording medium manufactured from the photopolymer composition is provided.

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

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

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

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

In addition, in this specification, a hologram means 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, pre-full-aperture hologram, white light transmission hologram ("rainbow hologram"), Denisyuk hologram, biaxial reflection hologram, edge-literature ( Edge-literature includes all visual holograms such as holograms or holographic stereograms.

In the present specification, the alkyl group may be straight-chain or branched-chain, and the number of carbon atoms is not particularly limited, but is preferably 1 to 40. According to one embodiment, the number of carbon atoms of the alkyl group is 1 to 20. According to another exemplary embodiment, the number of carbon atoms of the alkyl group is 1 to 10. 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, 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, etc., but is not limited thereto.

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

According to one embodiment of the invention,

polymeric matrices or precursors thereof; photoreactive monomers; photoinitiators; And a compound represented by Formula 1; and a photopolymer composition for forming a hologram is provided.

[Formula 1]

In Formula 1,

R ₁ and R ₂ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 5 carbon atoms,

n and m are integers from 1 to 10;

R ₃ and R ₄ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 5 carbon atoms,

X ₁ and X ₂ may be the same as or different from each other, and each independently represents a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms or a functional group of Formula 2, and at least one of X ₁ and X ₂ is a functional group of Formula 2 above. to be.

[Formula 2]

In Formula 2, Y ₁ is a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,

Y ₂ is a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms, or a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms bonded to an alkoxy group, or a straight-chain bonded to a heterocyclic ring having 2 to 10 carbon atoms containing at least one oxygen. or a branched chain alkyl group.

The present inventors have experimented with the fact that a hologram formed from a photopolymer composition including the compound of Formula 1 can realize a greatly improved refractive index modulation value and excellent durability against temperature and humidity compared to previously known holograms even in a thinner thickness range. It was confirmed through and the invention was completed.

According to the use of the compound of formula 1, the crosslinking density is optimized when manufacturing a coating film or hologram from the photopolymer composition, so that excellent durability against temperature and humidity can be secured compared to the existing matrix, and the above-mentioned optimization of crosslinking density can be achieved. Through this, the recording characteristics can be improved by maximizing the modulation of the refractive index by increasing the mobility between the photoreactive monomer having a high refractive index and the component having a low refractive index.

The contents of the compound of Formula 1 are as described above.

More specifically, in Formula 1,

R ₁ , R ₂ , R ₃ and R ₄ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 3 carbon atoms,

n and m are integers from 1 to 3;

X ₁ and X ₂ may be the same as or different from each other, and may be a functional group represented by Chemical Formula 2 above.

As described above, one or both ends of the compound of Formula 1 may be bonded to the functional group of Formula 2.

As the functional group of Chemical Formula 2 is combined, molecular fluidity or effective size of the molecule may increase, and accordingly, the photopolymer composition for forming a hologram and the hologram recording medium formed therefrom more effectively form a diffraction grating. effect can be realized.

More specifically, in Formula 2, Y ₁ is an alkylene group having 1 to 3 carbon atoms, and Y ₂ may be a linear or branched chain alkyl group having 1 to 10 carbon atoms or a linear or branched chain alkyl group having 3 to 8 carbon atoms. there is.

Alternatively, in Chemical Formula 2, Y ₁ is an alkylene group having 1 to 3 carbon atoms, and Y ₂ is a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms to which an alkoxy is bonded, or a hetero group having 2 to 10 carbon atoms containing at least one oxygen. It may be a straight-chain or branched-chain alkyl group to which a ring is attached.

The heterocycle includes at least one atom or heteroatom other than carbon. Specifically, the heteroatom may include at least one atom selected from the group consisting of O, N, Se, and S, and more specifically, One or more O may be included.

The heterocycle may be substituted or unsubstituted. Specifically, a halogen group, an aliphatic functional group having 1 to 10 carbon atoms, or an aromatic functional group having 6 to 20 carbon atoms may be substituted for the carbon included in the heterocyclic ring having 2 to 10 carbon atoms and including one or more oxygen atoms.

More specifically, the compound of Formula 1 may include any one selected from the group represented by the following formula.

The compound of Formula 1 may have a refractive index of 1.45.

Since the compound of Chemical Formula 1 contains a relatively high content of fluorine in the molecule and has stability with little reactivity and has refractive properties, when added to the photopolymer composition, the refractive index of the polymer matrix can be lowered, thereby reducing the refractive index of the monomer and The refractive index modulation of can be maximized.

The refractive index of the polymer matrix may be 1.46 to 1.53.

The polymer matrix may include a (meth)acrylate-based (co)polymer and a silane crosslinking agent in which a silane-based functional group is located in a branched chain.

The polymer matrix including the (meth)acrylate-based (co)polymer and the silane crosslinking agent in which the silane-based functional groups are located in the branched chain or a precursor thereof serves as a support for final products such as the photopolymer composition and a film manufactured therefrom. In the hologram formed from the photopolymer composition, a portion having a different refractive index may serve to increase refractive index modulation.

As described above, the polymer matrix may include a (meth)acrylate-based (co)polymer and a silane crosslinking agent in which a silane-based functional group is located in a branched chain. Accordingly, the precursor of the polymer matrix includes a monomer or oligomer forming the polymer matrix, and specifically, a (meth)acrylate-based (co)polymer in which the silane-based functional group is located in a branched chain, or a monomer thereof or the above It may include an oligomer of a monomer, and a silane crosslinking agent, or a monomer thereof or an oligomer of the monomer.

The (meth)acrylate-based (co)polymer and the silane crosslinking agent in which the above-mentioned silane-based functional group is located in the branched chain on the polymer matrix may exist as separate components, and may also be in the form of a complex formed by reacting them with each other. can exist

In the (meth)acrylate-based (co)polymer, a silane-based functional group may be located in a branched chain. The silane-based functional group may include a silane functional group or an alkoxy silane functional group, and preferably, a trimethoxysilane group may be used as the alkoxy silane functional group.

The silane-based functional group may crosslink the (meth)acrylate-based (co)polymer and the silane crosslinking agent by forming a siloxane bond through a sol-gel reaction with the silane-based functional group included in the silane crosslinking agent.

The silane crosslinking agent may be a compound having an average of one or more silane-based functional groups per molecule, or a mixture thereof, or a compound containing one or more silane-based functional groups. The silane-based functional group may include a silane functional group or an alkoxy silane functional group, and preferably, a triethoxysilane group may be used as the alkoxy silane functional group. The silane-based functional group may form a siloxane bond through a sol-gel reaction with the silane-based functional group included in the (meth)acrylate-based (co)polymer to crosslink the (meth)acrylate-based (co)polymer and the silane crosslinking agent. there is.

In this case, the equivalent of the silane-based functional group of the silane crosslinking agent may be 200 g/equivalent to 1000 g/equivalent. Accordingly, the crosslinking density between the (meth)acrylate-based (co)polymer and the silane crosslinking agent is optimized, so that excellent durability against temperature and humidity can be secured compared to the existing matrix. In addition, by optimizing the crosslinking density described above, the mobility between the photoreactive monomer having a high refractive index and the component having a low refractive index is increased, thereby maximizing the modulation of the refractive index, thereby improving recording characteristics.

If the equivalent of the silane-based functional group included in the silane crosslinking agent is excessively increased to 1000 g/equivalent or more, the diffraction grating interface after recording may collapse due to a decrease in the crosslinking density of the matrix, resulting in a loose crosslinking density and a low glass transition temperature. As a result, monomers and plasticizer components may be eluted to the surface to generate haze.

If the equivalent of the silane-based functional group included in the silane crosslinking agent is excessively reduced to less than 200 g/equivalent, the crosslinking density becomes too high, which hinders the fluidity of the monomer and plasticizer components, thereby causing a problem in that recording characteristics are significantly lowered. can

More specifically, the silane crosslinking agent may include a linear polyether main chain having a weight average molecular weight of 100 to 2000, or 300 to 1000, or 300 to 700, and a silane-based functional group bonded to an end or branched chain of the main chain.

The linear polyether main chain having a weight average molecular weight of 100 to 2000 may include a repeating unit represented by Formula 3 below.

[Formula 3]

-(R ₈ O) _n -R ₈ -

In Formula 3, R ₈ is an alkylene group having 1 to 10 carbon atoms, and n is an integer of 1 or more, or 1 to 50, or 5 to 20, or 8 to 10.

By introducing flexible polyether polyol into the main chain of the silane crosslinking agent, the fluidity of components can be improved by controlling the glass transition temperature and crosslinking density of the matrix.

On the other hand, the bond between the silane-based functional group and the polyether main chain may be through a urethane bond. Specifically, the silane-based functional group and the polyether main chain may form a bond with each other through a urethane bond, and more specifically, the silicon atom included in the silane-based functional group is directly connected to the nitrogen atom of the urethane bond or has 1 to 10 carbon atoms. It is bonded through an alkylene group, and the R8 functional group included in the polyether main chain can be directly bonded to the oxygen atom of the urethane bond.

In this way, the silane-based functional group and the polyether main chain are bonded through a urethane bond, wherein the silane crosslinking agent is prepared through a reaction between an isocyanate compound containing a silane-based functional group and a linear polyether polyol compound having a weight average molecular weight of 100 to 2000 because it is a reaction product.

More specifically, the isocyanate compound is an aliphatic, cycloaliphatic, aromatic or araliphatic mono-isocyanate di-isocyanate, tri-isocyanate or poly-isocyanate; or oligo-isocyanates of di-isocyanates or triisocyanates having a urethane, urea, carbodiimide, acylurea, isocyanurate, allophanate, biuret, oxadiazinetrione, uretdione or iminooxadiazinedione structure or poly-isocyanate; may be included.

A specific example of the isocyanate compound containing the silane-based functional group may include 3-isocyanatopropyltriethoxysilane.

In addition, the polyether polyol is, for example, a polyaddition product of styrene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin, and mixed adducts and graft products thereof; and polyether polyols obtained by condensation of polyhydric alcohols or mixtures thereof and those obtained by alkoxylation of polyhydric alcohols, amines and amino alcohols.

Specific examples of the polyether polyol include an OH functionality of 1.5 to 6 and a number average molecular weight between 200 and 18000 g/mol, preferably an OH functionality between 1.8 and 4.0 and a number average molecular weight between 600 and 8000 g/mol; poly(propylene oxide), poly(ethylene oxide) and combinations thereof in the form of random or block copolymers, particularly preferably having an OH functionality from 1.9 to 3.1 and a number average molecular weight from 650 to 4500 g/mol, or poly(tetrahydrofuran) and mixtures thereof.

As such, when the silane-based functional group and the polyether main chain are bonded through a urethane bond, the silane crosslinking agent can be more easily synthesized.

The weight average molecular weight (measured by GPC) of the silane crosslinking agent may be 1000 to 5,000,000. A weight average molecular weight means the weight average molecular weight (unit: g/mol) of polystyrene conversion 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 conventionally known analyzer and a detector such as a differential refraction detector (Refractive Index Detector) and an analysis column may 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 (Chloroform), and a flow rate of 1 mL/min.

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

Examples of the (meth)acrylate repeating unit in which the silane-based functional group is located in the branched chain include a repeating unit represented by Chemical Formula 4 below.

[Formula 4]

In Formula 4, R ₁ to R ₃ are each independently an alkyl group having 1 to 10 carbon atoms, R ₄ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₅ is an alkylene group having 1 to 10 carbon atoms.

Preferably, in Formula 4, R ₁ to R ₃ are each independently a methyl group having 1 carbon atom, R ₄ is a methyl group having 1 carbon atom, and R ₅ is a propylene group having 3 carbon atoms, derived from 3-Methacryloxypropyltrimethoxysilane (KBM-503) The repeating unit or R ₁ to R ₃ are each independently a methyl group having 1 carbon atom, R ₄ is hydrogen, and R ₅ is a repeating unit derived from 3-acryloxypropyltrimethoxysilane (KBM-5103), which is a propylene group having 3 carbon atoms.

Further, as an example of the (meth)acrylate repeating unit, a repeating unit represented by Chemical Formula 5 below may be mentioned.

[Formula 5]

In Formula 5, R ₆ is an alkyl group having 1 to 20 carbon atoms, R ₇ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and preferably, in Formula 5, R ₆ is a butyl group having 4 carbon atoms, and R ₇ is It may be a repeating unit derived from butyl acrylate, which is hydrogen.

The molar ratio between the repeating unit of Chemical Formula 5 and the repeating unit of Chemical Formula 4 may be 0.5:1 to 14:1. If the molar ratio of the repeating unit of Chemical Formula 4 is excessively reduced, the crosslinking density of the matrix is too low to function as a support, and thus the recording characteristics may decrease after recording. If it increases, the crosslinking density of the matrix becomes too high, and the fluidity of each component decreases, and the refractive index modulation value may decrease.

The weight average molecular weight (measured by GPC) of the (meth)acrylate-based (co)polymer may be 100,000 to 5,000,000, or 300,000 to 900,000. The weight average molecular weight means 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 conventionally known analyzer and a detector such as a differential refraction detector (Refractive Index Detector) and an analysis column may 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 (Chloroform), and a flow rate of 1 mL/min.

Meanwhile, the (meth)acrylate-based (co)polymer has an equivalent weight of the silane-based functional group of 300 g/equivalent to 2000 g/equivalent, or 500 g/equivalent to 2000 g/equivalent, or 550 g/equivalent to 1800 g /equivalent, or 580 g/equivalent to 1600 g/equivalent, or 586 g/equivalent to 1562 g/equivalent.

The silane-based functional group equivalent weight is equivalent (g/equivalent) for one silane-based functional group, and is a value obtained by dividing the weight average molecular weight of the (meth)acrylate-based (co)polymer by the number of silane-based functional groups per molecule. The smaller the equivalent value, the higher the functional group density, 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 silane crosslinking agent is optimized, so that excellent durability against temperature and humidity can be secured compared to the existing matrix. In addition, by optimizing the crosslinking density described above, the mobility between the photoreactive monomer having a high refractive index and the component having a low refractive index is increased, thereby maximizing the modulation of the refractive index, thereby improving recording characteristics.

If the equivalent of the silane-based functional group included in the (meth)acrylate-based (co)polymer is excessively reduced to less than 300 g/equivalent, the crosslinking density of the matrix becomes too high, impairing the fluidity of the components, thereby reducing the recording characteristics. decrease may occur. In addition, when the equivalent of the silane-based functional group included in the (meth)acrylate-based (co)polymer is excessively increased to more than 2000 g/equivalent, the crosslinking density is too low to function as a support, resulting in The boundary surface of the diffraction gratings collapses, and the refractive index modulation value may decrease over time.

Meanwhile, based on 100 parts by weight of the (meth)acrylate-based (co)polymer, the content of the silane crosslinking agent may be 10 parts by weight to 90 parts by weight, or 20 parts by weight to 70 parts by weight, or 22 parts by weight to 65 parts by weight. there is.

In the reaction product, if the content of the silane crosslinking agent is excessively reduced with respect to 100 parts by weight of the (meth)acrylate-based (co)polymer, the curing rate of the matrix is remarkably slowed down and the function as a support is lost, and the interface of the diffraction grating after recording is lost. This can easily break down, and in the reaction product, when the content of the silane crosslinking agent is excessively increased with respect to 100 parts by weight of the (meth)acrylate-based (co)polymer, the curing rate of the matrix is increased, but the content of the reactive silane group Excessive increase causes compatibility problems with other components, resulting in haze.

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, the storage modulus (G′) value can be measured at a frequency of 1 Hz at room temperature (20 ° C to 25 ° C) using a discovery hybrid rheometer (DHR) equipment of TA Instruments.

In addition, the glass transition temperature of the reaction product may be -40 ℃ to 10 ℃. As a specific example of the method for measuring the glass transition temperature, the photopolymerization composition is coated in the range of -80 ° C to 30 ° C under the setting conditions of strain 0.1%, frequency 1Hz, heating rate 5 ° C / min using DMA (dynamic mechanical analysis) measuring equipment There is a method of measuring the change in the phase angle (Loss modulus) of the film.

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

As described above, in the process of photopolymerization of the photopolymer composition, the monomer is polymerized, and the refractive index is increased in a portion where a relatively large amount of polymer is present, and the refractive index is relatively low in a portion where a relatively large amount of polymer binder is present, resulting in refractive index modulation. , a diffraction grating is created 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)acrylonitrile. acrylic acid, etc., or a compound containing a vinyl group or a thiol group.

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

Another example of the photoreactive monomer may include 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 the monofunctional (meth)acrylate monomer include phenoxy benzyl (meth)acrylate, o-phenyl phenol ethylene oxide (meth)acrylate, benzyl (meth)acrylate, 2-(phenylthio)ethyl (meth)acrylate, or biphenylmethyl (meth)acrylate; and the like.

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 said weight average molecular weight means the weight average molecular weight of polystyrene conversion 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, commonly known photoinitiators may be used without particular limitations, but specific examples thereof include photoradical polymerization initiators, photocationic polymerization initiators, or photoanionic polymerization initiators.

Specific examples of the photo-radical polymerization initiator include imidazole derivatives, biimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxy pyridinium salts, thioxanthone derivatives, amine derivatives, and the like. More specifically, the photo-radical polymerization initiator includes 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), etc.

Examples of the photocationic polymerization initiator include diazonium salt, sulfonium salt, or iodonium salt, and examples thereof include sulfonic acid ester, imide sulfonate, and dialkyl-4 -hydroxy sulfonium salt, aryl sulfonic acid-p-nitrobenzyl ester, silanol-aluminum complex, (η6-benzene)(η5-cyclopentadienyl)iron(II), and the like. In addition, benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosylphthalic acid imide, and the like are also included. More specific examples of the photocationic polymerization initiator include 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. (Manufacturer: Nippon Soda) etc. commercially available products are mentioned.

Examples of the photoanionic polymerization initiator include borate salts, examples of which include BUTYRYL CHOLINE BUTYLTRIPHENYLBORATE and the like. 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 monomolecular (Type I) or bimolecular (Type II) initiator. (Type I) systems for the free radical photopolymerization are, for example, aromatic ketone compounds such as benzophenones, alkylbenzophenones, 4,4'-bis(dimethylamino)benzophenones in combination with tertiary amines (Michler's ) ketones), anthrones and halogenated benzophenones or mixtures of the above types. The bimolecular (type II) initiators include benzoin and its derivatives, benzyl ketals, acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bisacylophosphine oxide, phenylgly Oxyl esters, camphorquinones, alpha-aminoalkylphenones, alpha-,alpha-dialkoxyacetophenones, 1-[4-(phenylthio)phenyl]octane-1,2-dione 2-(O-benzoyloxime) and alpha -Hydroxyalkyl phenone etc. are mentioned.

The photopolymer composition of the embodiment includes: 20 to 300 parts by weight of a photoreactive monomer, 0.1 to 10 parts by weight of a photoinitiator, based on 100 parts by weight of a polymer matrix or a precursor thereof; And 20 to 300 parts by weight of the compound of Formula 1; may include.

As will be described later, when the photopolymer composition further includes an organic solvent, the content of the aforementioned components is based on the total sum of these components (the total sum of components excluding the organic solvent).

The photopolymer composition may further include a compound represented by Chemical Formula 11 below.

Formula 11]

In Formula 11,

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;

k is an integer from 1 to 10;

R ₁₇ and R ₁₈ are each independently a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms or a functional group represented by Formula 21;

[Formula 21]

In Formula 21,

R ₂₁ , R ₂₂ and R ₂₃ are each independently a straight or branched chain alkylene group having 1 to 10 carbon atoms;

R ₂₄ is a straight or branched chain alkyl group having 1 to 10 carbon atoms;

l is an integer from 1 to 30;

The compound of Chemical Formula 11 is also a fluorine-based compound, has stability with little reactivity, and has low refractive properties, so 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 monomers. can

The compound of Formula 11 may include at least one functional group selected from the group consisting of an ether group, an ester group, and an amide group, and at least two difluoromethylene groups. More specifically, the fluorine-based compound may have a structure of Formula 11 in which a functional group including an ether group is bonded to both ends of a central functional group including a direct bond or an ether bond between two difluoromethylene groups.

The compound of Chemical Formula 11 may have a refractive index of less than 1.45 or greater than or equal to 1.3 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 lower refractive index than the photoreactive monomer, thereby maximizing refractive index modulation with the monomer.

Specifically, the photopolymer composition of the embodiment may include 20 to 300 parts by weight of the compound of Formula 11 based on 100 parts by weight of the polymer matrix or precursor thereof.

The compound of Formula 11 may have a weight average molecular weight (measured by GPC) of 300 or more, or 300 to 1000. The specific method of measuring the weight average molecular weight is as described above.

Meanwhile, when the photopolymer composition includes the compound of Formula 1 and the compound of Formula 11 together, the photoreactive monomer having a high refractive index and the photoreactive monomer having a low By increasing the mobility between components having a refractive index, the refractive index modulation is maximized, so that the effect of improving the recording characteristics can be further maximized.

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 onto the photopolymer composition and serves as an initiator that initiates polymerization of the monomer and crosslinking monomer. can do. The photopolymer composition may include 0.01 wt % to 30 wt %, or 0.05 wt % to 20 wt % of the photosensitive dye.

Examples of the photosensitive dye are not particularly limited, and various commonly known compounds may be used. Specific examples of the photosensitive dye include a sulfonium derivative of ceramidonin, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino-2-methylcera 6-acetylamino-2-methylceramidonin, eosin, erythrosine, rose bengal, thionine, basic yellow, pinacyanol chloride ), rhodamine 6G, gallocyanine, ethyl violet, Victoria blue R, Celestine blue, QuinaldineRed, crystal violet (crystal violet), brilliant green, astrazon orange G, darrow red, pyronin Y, basic red 29, pyrylium 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 a mixture of two or more thereof.

Specific examples of such an organic solvent include ketones such as methyl ethyl ketone, 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 thereof.

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 in the organic solvent. If the content of the organic solvent in the photopolymer composition is too small, flowability of the photopolymer composition is lowered, and defects such as streaks may occur in a final film. In addition, when an excessive amount of the organic solvent is added, the solids content is lowered, and coating and film formation are not sufficiently performed, resulting in deterioration in physical properties or surface characteristics of the film and defects in drying and curing processes. Accordingly, the photopolymer composition may include an organic solvent such that the total solid concentration 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 commonly known catalyst to promote polymerization of the polymer matrix or the photoreactive monomer. Examples of the catalyst include tin octanoate, zinc octanoate, dibutyltin dilaurate, dimethylbis[(1-oxoneodecyl)oxy]stannane, dimethyltin dicarboxylate, zirconium bis(ethylhexane) norate), zirconium acetylacetonate, p-toluenesulfonic acid or tertiary amines such as 1,4-diazabicyclo[2.2.2]octane, diazabicyclononane, diazabicycloundecane , 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 an antifoaming agent or a phosphate-based plasticizer, and a silicone-based reactive additive may be used as the antifoaming agent, and Tego Rad 2500 is an example thereof. An example 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-mentioned fluorine-based compound. 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 made from a photopolymer composition may be provided.

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

The hologram recording medium can implement a refractive index modulation value (n) of 0.020 or more, or 0.021 or more, 0.022 or more, or 0.023 or more, or 0.020 to 0.035, or 0.027 to 0.030 even with a thickness of 5 μm to 30 μm.

In addition, the hologram recording medium can implement a diffraction efficiency of 50% or more, or 85% or more, or 85 to 99% at a thickness of 5 μm to 30 μm.

The photopolymer composition of one embodiment is uniformly mixed with each component included therein, dried and cured at a temperature of 20 ° C. or higher, and then subjected to a predetermined exposure process to obtain a light in the entire visible range and near-ultraviolet region (300 to 800 nm). ) can be fabricated into holograms for optical applications in

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

In the photopolymer composition of one embodiment, a conventionally known mixer, stirrer, mixer, etc. may be used for mixing of each component included therein without particular limitation, and the temperature during 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, in the photopolymer composition of one embodiment, a component forming a polymer matrix or a precursor thereof is first homogenized and mixed, and then, at the time of adding the above-described silane crosslinking agent, the photopolymer composition is a liquid formulation that is cured at a temperature of 20 ° C. or higher This can be.

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

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

As described above, a medium in which no visual hologram is recorded may be prepared through 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 a process of mixing and curing the photopolymer composition 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 element include an optical lens, a mirror, a deflecting mirror, a filter, a diffusing screen, a diffractive member, a light guide, a waveguide, a holographic optical element having a function of a projection screen and/or a mask, and a medium and light of an optical memory system. Diffusion plates, optical wavelength splitters, reflective and transmissive color filters, and the like are exemplified.

An example of an optical element including the hologram recording medium may include a hologram display device.

The hologram display device includes a light source unit, an input unit, an optical system, and a display unit. The light source unit 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 unit. 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, and the like. The optical system includes an input beam for sending a laser beam emitted from a light source to an input unit, a recording beam for sending to a display unit, a reference beam, an erase beam, and a readout. It can be distributed by chulbeam, etc.

The display unit may receive 3D image information of the object from the input unit, record it on a hologram plate made of an optically addressed SLM (SLM), and reproduce the 3D image of the object. At this time, 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. Meanwhile, the hologram plate may be moved between a position where a 3D image is input and a position where it is reproduced.

According to the present invention, a photopolymer composition capable of more efficiently and easily providing a photopolymer layer capable of implementing a higher refractive index modulation value even in a thin thickness range, and a hologram recording capable of implementing a higher refractive index modulation value even in a thin thickness range A medium, an optical element, and a holographic recording method may be provided.

The invention is explained 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]

[Preparation Example 1: Manufacturing method of (meth)acrylate-based (co)polymer in which silane-based functional group is located in the branched chain]

154 g of butyl acrylate and 46 g of KBM-503 (3-methacryloxypropyltrimethoxysilane) were put in a 2L jacketed reactor, and diluted with 800 g of ethyl acetate. The reaction temperature was set to about 60 to 70 ° C, and stirring was performed for about 30 minutes to 1 hour. 0.02 g of n-dodecyl mercaptan was additionally added, and stirring was continued for about 30 minutes. Thereafter, 0.06 g of AIBN, a polymerization initiator, was added, and polymerization was carried out at the reaction temperature for 4 hours or more, and maintained until the residual acrylate content was less than 1%. A co)polymer (weight average molecular weight of about 500,000 to 600,000, Si-(OR) ₃ equivalent 1019 g/equivalent) was prepared.

[Production Example 2: Manufacturing method of silane crosslinking agent]

19.79 g of KBE-9007 (3-isocyanatopropyltriethoxysilane), 12.80 g of PEG-400, and 0.57 g of DBTDL were placed in a 1000 ml flask, and diluted with 300 g of tetrahydrofuran. After stirring at room temperature until it was confirmed by TLC that all the reactants were consumed, the reaction solvent was removed under reduced pressure.

28 g of a liquid product having a purity of 95% or more was separated in a yield of 91% through column chromatography under the dichloromethane:methyl alcohol = 30:1 developing solution condition to obtain a silane crosslinking agent.

[Preparation Example 3: Manufacturing method of non-reactive low refractive index material #1]

After adding Fluorinated tetraethylene glycol (4.10 g, 10 mmol), Acetone (20 mL) and Potassium carbonate (4.8 g, 35 mmol) to a 250 mL flask, stir at 20 ^o C for 1 hour.

After cooling to 0 °C and stirring, methyl chloroformate (2.84 g, 30 mmol) was added, the temperature was raised to 20 °C, and the mixture was stirred for 18 hours.

100 mL of water and 150 mL of ethyl acetate were added to the reaction mixture to separate the layers. The process of separating the organic layer and adding 150 mL of water to the organic layer to wash the organic layer was repeated twice.

25 mL of saturated sodium chloride aqueous solution was added to the organic layer, and the layer was separated and removed to remove the residue. Then, MgSO ₄ was added to the organic layer to remove all moisture, and the organic layer was distilled under reduced pressure. From the concentrated organic layer, non-reactive low refractive index material #1 of the following chemical formula was isolated through column chromatography (SiO ₂ ) (2.41 g, 46% yield)

¹ H NMR (CDCl ₃ ): δ 4.52 ( t , J = 7.5 Hz, 4H), 3.86 (s, 6H)

[Preparation Example 4: Manufacturing method of non-reactive low refractive index material #2]

Fluorinated tetraethylene glycol (14.4 g, 35 mmol), Acetone (70 mL), and potassium carbonate (16.9 g, 122.5 mmol) were added to a 500 mL round-bottom flask and stirred at 20 °C for 1 hour. While stirring and cooling to 0 ° C., n-butyl chloroformate (14.3 g, 105 mmol) was added at room temperature, and the temperature was raised to 20 ° C. and stirred for 18 hours.

300 mL of water and 450 mL of ethyl acetate were added to the reaction mixture to separate the layers. The process of separating the organic layer and adding 300 mL of water to the organic layer and washing was repeated twice.

25 mL of saturated sodium chloride aqueous solution was added to the organic layer, and the layer was separated and removed to remove the residue. Then, MgSO ₄ was added to the organic layer to remove all moisture, and the organic layer was distilled under reduced pressure. From the concentrated organic layer, a non-reactive low refractive index material #2 of the following chemical formula was isolated through column chromatography (SiO ₂ ) (9.40 g, 44%)

¹ H NMR (CDCl ₃ ): δ 4.50 (3, J = 7.5 Hz, 4H), 4.25 (t, J = 5.4 Hz, 4H), 1.69-1.65 (m, 4H), 1.43-1.39 (m, 4H) , 0.95 (t, J = 7.0 Hz, 6H)

[Preparation Example 5: Manufacturing method of non-reactive low refractive index material #3]

Add phosgene (115 mL, 210 mmol, 20 wt% in toluene) to a 500 mL round-bottom flask and cool to 0 ^o C. 1,4-butanediol monomethyl ether (7.3 g, 70 mmol) was added slowly. After raising the temperature to 25 ℃ and stirring for 3 hours, it is confirmed by TLC that all the reactants are consumed. It is distilled under reduced pressure to remove all volatile substances. 4-methoxybutyl chloroformate was obtained by adding 100 mL of toluene and distilling under reduced pressure to remove residual volatiles twice. The obtained chloroformed product is used directly in the next step without additional purification.

Fluorinated tetraethylene glycol (8.2 g, 20 mmol), acetone (40 mL), and potassium carbonate (9.67 g, 70 mmol) were added to a 500 mL round-bottom flask and stirred at 20 ^° C for 1 hour. After cooling to 0 ^o C and stirring, 4-methoxybutyl chloroformate (10 g, 60 mmol) was added. After adding, the temperature is raised to 20°C, and the mixture is stirred for 18 hours.

300 mL of water and 450 mL of ethyl acetate were added to the reaction mixture to separate the layers. The process of separating the organic layer and adding 300 mL of water to the organic layer and washing was repeated twice.

25 mL of saturated sodium chloride aqueous solution was added to the organic layer, and the layer was separated and removed to remove the residue. Then, MgSO ₄ was added to the organic layer to remove all moisture, and the organic layer was distilled under reduced pressure. From the concentrated organic layer, a non-reactive low refractive index material #3 of the following chemical formula was isolated through column chromatography (SiO ₂ ) (6.23 g, 47%)

¹ H NMR (CDCl ₃ ): δ 4.53 (t, J = 7.2 Hz, 4H), 4.27 (t, J = 5.4 Hz, 4H), 3.44 (t, J = 5.8 Hz, 4H), 3.33 (s, 6H) ), 1.62-1.84 (m, 8H)

[Preparation Example 6: Manufacturing method of non-reactive low refractive index material #4]

Add phosgene (86.5 mL, 157.5 mmol, 20 wt% in toluene) to a 500 mL round-bottom flask and cool to 0 ^o C. 2-methoxypropanol (4.7 g, 52.5 mmol) was added slowly. After raising the temperature to 25 ℃ and stirring for 3 hours, it is confirmed by TLC that all the reactants are consumed. It is distilled under reduced pressure to remove all volatile substances. 2-methoxypropyl chloroformate was obtained by adding 100 mL of toluene and distilling under reduced pressure to remove residual volatiles twice. The obtained chloroformate is used directly in the next step without additional purification.

Fluorinated tetraethylene glycol (6.2 g, 15 mmol), Acetone (30 mL), and potassium carbonate (7.3 g, 52.5 mmol) were added to a 500 mL round-bottom flask and stirred at 20 ^° C for 1 hour. After cooling to 0 ^° C and stirring, 2-methoxypropyl chloroformate (6.9 g, 45 mmol) was added, and the temperature was raised to 20 ° C and stirred for 18 hours.

300 mL of water and 450 mL of ethyl acetate were added to the reaction mixture to separate the layers. The process of separating the organic layer and adding 300 mL of water to the organic layer and washing was repeated twice.

25 mL of saturated sodium chloride aqueous solution was added to the organic layer, and the layer was separated and removed to remove the residue. Then, MgSO ₄ was added to the organic layer to remove all moisture, and the organic layer was distilled under reduced pressure. A non-reactive low refractive index material #4 was separated from the concentrated organic layer through column chromatography (SiO ₂ ). (2.31 g, 24%)

¹ H NMR (CDCl ₃ ): δ 4.53 (t, J = 7.4 Hz, 4H), 4.35-4.44 (m, 4H), 3.65-3.70 (m, 2H), 3.40 (s, 6H), 1.29 (d, J = 6.5 Hz, 6H)

[Preparation Example 7: Manufacturing method of non-reactive low refractive index material #5]

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 1000ml flask. After dissolving in 500 g of tetrahydrofuran, 4.40 g of sodium hydride (60% dispersion in mineral oil) was carefully added several times while 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 by ¹ H NMR that the reactants were all consumed, the reaction solvent was removed under reduced pressure. After collecting the organic layer by extracting with 300 g of dichloromethane three times, filtering with magnesium sulfate and removing all dichloromethane under reduced pressure to obtain 29 g of a liquid product having a purity of 95% or more in a yield of 98%.

[Examples and Comparative Examples: Preparation of photopolymer composition]

As shown in Table 1 or Table 2 below, the silane polymer obtained in Preparation Examples 1 to 2, the photoreactive monomer (high refractive acrylate, refractive index 1.600, HR6022 [Miwon]), the non-reactive low refractive index material of Preparation Examples 3 to 7 , Tributyl phosphate [TBP], molecular weight 266.31, refractive index 1.424, manufactured by Sigma-Aldrich), safranin O (dye, manufactured by Sigma-Aldrich), Ebecryl P-115 (SK entis), Borate V (Spectra group), Irgacure 250 (BASF), silicon-based reactive additive (Tego Rad 2500), and methyl isobutyl ketone (MIBK) were mixed in a light-blocking state, and stirred for about 10 minutes with a Paste mixer to obtain a transparent coating solution.

The above-described silane crosslinking agent or network structured sila crosslinking agent (Sibond H-5) of Preparation Example 2 was added to the coating solution, and further stirred for 5 to 10 minutes. Thereafter, 0.02 g of DBTDL as a catalyst was added to the coating solution, stirred for about 1 minute, and then coated to a thickness of 6 μm on a TAC substrate having a thickness of 80 μm using a meyer bar, and dried at 40° C. for 1 hour.

Then, the sample was left for 24 hours or more in a dark room under constant temperature and humidity conditions at about 25° C. and a relative humidity of 50 RH%.

[Experimental Example: Holographic Recording]

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

(2) Measurement of diffraction efficiency (η)

Holographic recording is performed through the interference of two coherent lights (reference light and object light), and in transmissive recording, two beams are incident on the same surface of the sample. The diffraction efficiency varies according to the angle of incidence of the two beams, and becomes non-slanted when the angle of incidence of the two beams is the same. In non-slanted writing, the angle of incidence of the two beams is the same with respect to the normal, so the diffraction grating is created perpendicular to the film.

Recording was performed in a transmissive non-slanted manner (2θ = 45°) using a 532 nm wavelength laser, and 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)

The lossless dielectric grating of the transmission type 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 laser loss (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 above 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 Compositions (Unit: g) of Examples and Holographic Recording Media Prepared Therefrom division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 (meth)acrylate-based copolymer Preparation Example 1 23.1 23.1 23.1 23.1 23.1 23.1 23.1 23.1 Linear silane crosslinking agent Preparation Example 2 8.4 8.4 8.4 8.4 8.4 8.4 8.4 8.4 photoreactive monomer HR6022 31.5 31.5 31.5 31.5 31.5 31.5 31.5 31.5 Dye safranin O 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Amine Ebecryl P-115 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 Borate salt Borate V 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Onium salt Irgacure 250 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Non-reactive plasticizer (TBP) Tributyl phosphate 0 17.2 0 17.2 17.2 17.2 Non-reactive low refractive materials Preparation Example 3 34.4 17.2 Production Example 4 34.4 17.2 Preparation Example 5 34.4 17.2 Preparation Example 6 34.4 17.2 catalyst Dibutyltin dilaurate (DBTDL) 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 additive Tego Rad 2500 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 menstruum MIBK 300 300 300 300 300 300 300 300 Coating thickness (unit: ㎛) 6 6 6 6 6 6 6 6 I _loss (%) 25 26 24 25 24 24 25 26 △n 0.025 0.021 0.024 0.020 0.026 0.021 0.025 0.020

* Non-reactive plasticizer: Tributyl phosphate (molecular weight 266.31, refractive index 1.424, purchased from Sigma-Aldrich)

Experimental Example Measurement Results of Photopolymer Compositions of Comparative Examples and Holographic Recording Media Prepared Therefrom division Comparative Example 1 Comparative Example 2 Comparative Example 3 (meth)acrylate-based copolymer Preparation Example 1 23.1 23.1 23.1 Linear silane crosslinking agent Preparation Example 2 8.4 8.4 8.4 photoreactive monomer HR6022 31.5 31.5 31.5 Dye safranin O 0.1 0.1 0.1 Amine Ebecryl P-115 1.7 1.7 1.7 Borate salt Borate V 0.3 0.3 0.3 Onium salt Irgacure 250 0.1 0.1 0.1 non-reactive plasticizer
(TBP) Tributyl phosphate 34.4 0 17.2 Non-reactive low index material (P3) Preparation Example 7 0 34.4 17.2 catalyst Dibutyltin dilaurate (DBTDL) 0.02 0.02 0.02 additive Tego Rad 2500 0.3 0.3 0.3 menstruum MIBK 300 300 300 Coating thickness (unit: ㎛) 6 6 6 I _loss (%) 25 28 27 △n 0.018 0.015 0.019

As shown in Tables 1 and 2, it was confirmed that the photopolymer compositions of Examples had a refractive index modulation value (Δn) of 0.020 or more and excellent diffraction efficiency.

In contrast, the photopolymer coating film provided by the composition of the Comparative Example had a relatively low diffraction efficiency and a relatively high laser loss (Iloss) compared to that of the Examples.

Claims (17)

polymeric matrices or precursors thereof;
photoreactive monomers;
photoinitiators; and
A photopolymer composition for forming a hologram, comprising: a compound of Formula 1 below:
[Formula 1]

In Formula 1,
R ₁ and R ₂ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 5 carbon atoms,
n and m are integers from 1 to 10;
R ₃ and R ₄ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 5 carbon atoms,
X ₁ and X ₂ may be the same as or different from each other, and are each independently a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms, or a functional group represented by Formula 2 below, and at least one of X ₁ and X ₂ is a functional group represented by Formula 2 below. ego,
[Formula 2]

In Formula 2, Y ₁ is a straight-chain or branched-chain alkylene group having 1 to 10 carbon atoms,
Y ₂ is a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms, or a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms bonded to an alkoxy group, or a straight-chain bonded to a heterocyclic ring having 2 to 10 carbon atoms containing at least one oxygen. or a branched chain alkyl group.
According to claim 1,
In Formula 1,
R ₁ , R ₂ , R ₃ and R ₄ may be the same as or different from each other, and each is a perfluoro-alkylene group having 1 to 3 carbon atoms,
n and m are integers from 1 to 3;
X ₁ and X ₂ may be the same as or different from each other, and are functional groups of Formula 2,
A photopolymer composition for forming a hologram.
According to claim 1 or 2,
In Formula 2,
Y ₁ is an alkylene group having 1 to 3 carbon atoms;
Y ₂ is a straight or branched chain alkyl group having 1 to 10 carbon atoms;
A photopolymer composition for forming a hologram.
According to claim 1 or 2,
In Formula 2,
Y ₁ is an alkylene group having 1 to 3 carbon atoms;
Y ₂ is a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms bonded to an alkoxy group, or a straight-chain or branched-chain alkyl group bonded to a hetero ring having 2 to 10 carbon atoms containing at least one oxygen, photopolymer composition for forming a hologram .
According to claim 1,
The refractive index of the compound of Formula 1 is less than 1.45, a photopolymer composition for forming a hologram.
According to claim 1,
The photopolymer composition for forming a hologram, wherein the polymer matrix has a refractive index of 1.46 to 1.53.
According to claim 1,
The polymer matrix includes a (meth)acrylate-based (co)polymer and a silane crosslinking agent in which silane-based functional groups are located in branched chains, a photopolymer composition for forming a hologram.
According to claim 7,
A photopolymer composition for forming a hologram, wherein the content of the silane crosslinking agent is 10 parts by weight to 90 parts by weight, based on 100 parts by weight of the (meth)acrylate-based (co)polymer.
According to claim 7,
The silane crosslinking agent includes a linear polyether main chain having a weight average molecular weight of 100 to 2000 and a silane-based functional group bonded to an end or branched chain of the main chain.
According to claim 1,
The photoreactive monomer comprises a multifunctional (meth) acrylate monomer or a monofunctional (meth) acrylate monomer, a photopolymer composition for forming a hologram.
According to claim 1,
The photopolymer composition for forming a hologram, wherein the photoreactive monomer has a refractive index of 1.5 or more.
According to claim 1,
100 parts by weight of the polymer matrix or its precursor
20 to 300 parts by weight of photoreactive monomer
0.1 to 10 parts by weight of a photoinitiator; and
20 to 300 parts by weight of the compound of Formula 1; containing a photopolymer composition for forming a hologram.
According to claim 1,
A photopolymer composition for forming a hologram, further comprising a compound represented by Formula 11 below:
[Formula 11]

In Formula 11,
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;
k is an integer from 1 to 10;
R ₁₇ and R ₁₈ are each independently a straight-chain or branched-chain alkyl group having 1 to 10 carbon atoms or a functional group represented by Formula 21 below;
[Formula 21]

In Formula 21,
R ₂₁ , R ₂₂ and R ₂₃ are each independently a straight or branched chain alkylene group having 1 to 10 carbon atoms;
R ₂₄ is a straight or branched chain alkyl group having 1 to 10 carbon atoms;
l is an integer from 1 to 30;
According to claim 13,
100 parts by weight of the polymer matrix or its precursor
A photopolymer composition for forming a hologram comprising 20 to 300 parts by weight of the compound of Formula 11.
A hologram recording medium prepared from the photopolymer composition of claim 1.
An optical element comprising the hologram recording medium of claim 15.
A holographic recording method comprising the step of selectively polymerizing a photoreactive monomer included in the photopolymer composition of claim 1 by means of a coherent laser.