WO2019112358A1 - Photopolymer composition - Google Patents

Abstract

The present invention relates to: a hologram recording medium having a main relaxation temperature of 0℃ or lower as determined by dynamic mechanical analysis in the -80℃ to 30℃ range, the main relaxation temperature being the point at which temperature-induced rate of change of the phase angle is the greatest; an optical element comprising the hologram recording medium; and a holographic recording method comprising a step for selectively polymerizing optically-responsive monomers contained in the hologram recording medium by means of a coherent laser.

Description

 Title of the Invention

 Photopolymer composition

 TECHNICAL FIELD

 Cross-reference with related application (s)

 This application is related to Korean Patent Application No. 10-2017-0168049, dated December 8, 2017,

Claims the benefit of priority based on Korean Patent Application No. 10-2018-0156152, filed on December 6, 2018, the entire contents of which are incorporated herein by reference.

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

 TECHNICAL BACKGROUND OF THE INVENTION

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

 In the case of using a photopolymer (photosensitive resin), since the optical interference pattern can be easily stored in the hologram by photopolymerization of the low-molecular monomer, the optical lens, the mirror, the deflecting mirror, the filter, the diffusing screen, , A holographic optical element having a function of a projection screen and / or a mask, a medium of an optical memory system and a light diffusing plate, an optical wavelength splitter, a reflection type, and a transmission type color filter.

 Typically, the photopolymer composition for hologram production comprises a polymeric binder, a monomer, and a photoinitiator, and irradiates the photosensitive film produced from such a composition with laser interference light to induce photopolymerization of the local monomer.

 In such a photopolymerization process, the refractive index increases at a portion where a relatively large amount of monomer exists, and at a portion where a polymer binder is relatively present, a refractive index is relatively lowered to cause a refractive index modulation, and such a refractive index modulation generates a diffraction grating. The refractive index modulation value n is influenced by the thickness of the photopolymer layer and the diffraction efficiency DE, and the angular selectivity becomes wider as the thickness is known.

In recent years, a high diffraction efficiency and a stable hologram With the demand for the development of materials, various attempts have been made to manufacture a photopolymer layer having a small thickness and a large refractive index modulation value.

 DISCLOSURE OF THE INVENTION

 [Problem to be solved]

 An object of the present invention is to provide a hologram recording medium which has a thin thickness, realizes a large refractive index modulation value, and has improved durability against temperature and humidity. Further, the present invention is to provide an optical element including a hologram recording medium.

 The present invention also provides a holographic recording method comprising selectively polymerizing a photoreactive monomer contained in the hologram recording medium by a coherent laser.

 MEANS FOR SOLVING THE PROBLEMS

 In this specification, the main relaxation temperature (Tr) at which the rate of change of the phase angle with temperature in the dynamic analysis (dynami c mechanical analysis) is the largest in the range of -80 ° C to 30 ° C, Lt; RTI ID = 0.0 > 0 C < / RTI >

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

 Also, in this specification, a holographic recording method is provided which includes selectively polymerizing a photoreactive monomer contained in the hologram recording medium by a coherent laser.

 A hologram recording medium, an optical element, and a holographic recording method according to a specific embodiment of the present invention will be described in more detail below. In the present specification, (meth) acrylate means methacrylate or acrylate.

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

Also, in this specification, a hologram is formed by exposing all Means a recording medium in which optical information is recorded in a visible range and a near ultraviolet range (300 to 800 nm), and includes, for example, an in-line (Gabor) hologram, a biaxial hologram, (Holograms), holograms of pre-ful h-apertures, holograms of white light transmission ("rainbow holograms"), Deni syuk holograms, biaxial reflection holograms, edge-l iterature holograms or holographic stereograms stereograms, and the like.

In the present specification, the alkyl group may be linear or branched, and the number of carbon atoms is not particularly limited, but is preferably 1 to 40. According to one embodiment, the alkyl group has 1 to 20 carbon atoms. According to another embodiment, the alkyl group has 1 to 10 carbon atoms. According to another embodiment, the alkyl group has 1 to 6 carbon atoms. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, But are not limited to, pentyl, isopentyl, neopentyl, tert-pentyl, n-butyl, n-napyl, 1-methylpentyl, 2- methylpentyl, N-hexyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylbutyl, But are not limited to, dimethylheptyl _{, 1-} ethyl-propyl _, 1,1-dimethyl-propyl _, isohexyl _{, 2} -methylpentyl, ₄ -methylnucyl and 5-methylnucyl.

 In the present specification, the alkylene group is a divalent functional group derived from an alkane, for example, a straight chain, branched or cyclic group, and includes a methylene group, an ethylene group, a propylene group, an isobutylene group, Butylpentene, tert-butylpentene, pentylene, and naphtholene. According to one embodiment of the present invention, the main relaxation temperature (the main relaxation temperature), which is the point at which the rate of change of the phase angle with temperature in the dynamic analysis (dynami c mechanical analysis) in the range of -80 ° C to 30 ° C is the largest, ion temperature, Tr)

0 DEG C or less, may be provided. The present inventors have found that dynamic analysis (dynami c the main relaxation temperature (Tr), which is the point where the rate of change of the phase angle with respect to the temperature of the mechanical analysis is the maximum, is 0 ° C or less, or -

15 ° C or -15 ° C to -50 ° C can realize a large refractive index modulation value while having a thin thickness.

 As described above, in the range of -80 ° C to 30 ° C, the main relaxation temperature (damping temperature), which is the point at which the rate of change of phase mgle according to the temperature in the dynamic analysis (dynami c mechanical analysis, DMA) the mobility of the components constituting the hologram recording medium is increased even at room temperature depending on whether the temperature of the hologram recording medium is in the range of 0 ° C to -15 ° C or -15 ° C to -50 ° C So that the recording characteristics can be improved. Also, as the fluidity of the medium itself is increased, counter-di f fusions of low refractive materials are generated as opposed to the direction of diffusion of the monomer, thereby maximizing the refractive index modulation value.

 As is commonly known, the phase angle is an angle value of tan delta calculated by G '(loss modulus) (storage elastic modulus), and dynami c mechanical analysi s) can be derived.

 As described above, the main relaxation temperature (Tr) may be a point at which the rate of change of the phase angle with temperature in the dynamic analysis is the largest in the range of -80 ° C to 30 ° C . This phase angle is measured in a DMA extension mode while giving strain to a film type hologram recording medium at a constant frequency. It is possible to calculate the retardation change value according to the temperature by measuring the loss elastic modulus and the storage elastic modulus while changing the chamber temperature around the sample in the state where the continuous deformation occurs.

The kinetic analysis can be performed according to a conventionally known apparatus and method. Specifically, the kinetic analysis can be carried out with a strain of 0.1%, a frequency of 1 Hz and a rate of temperature increase of 5 ° C / min ≪ / RTI > On the other hand, the hologram recording medium of the above embodiment includes a polymer matrix or a precursor thereof; And a light-reactive monomer.

 The polymer matrix or precursor thereof may serve as a support for the hologram recording medium and the final product made therefrom, and the photoreactive monomer may serve as a recording monomer. Depending on their use, The photoreactive monomer may be selectively polymerized on the polymer matrix to cause refractive index modulation due to a portion having a different refractive index.

 The main relaxation temperature (Tr), which is the point at which the rate of change of the phase angle with temperature is greatest in the dynamic analysis (dynami c mechani cal analys s) in the range of -80 ° C to 30 ° C, When CTC or less is satisfied, specific examples of the polymer matrix or its precursor are not limited to a great extent.

 In addition, the refractive index of the polymer matrix is not particularly limited, but may be, for example, from 1.45 to 1.70, or from 1.455 to 1.60, or from 1.46 to 1.53. Examples of the polymer matrix or a precursor thereof include a polymer matrix containing a (meth) acrylate-based (co) polymer in which a silane-based functional group is located in a branch chain, and a silane crosslinking agent.

 The (meth) acrylate system in which the silane-based functional group is located in the branch chain

A hologram formed from a polymer matrix comprising a (co) polymer and a silane crosslinker, or a photopolymer composition comprising the precursor thereof, has significantly improved refractive index modulation values and superior temperature and humidity durability It can be implemented.

 Wherein the silane crosslinking agent and the silane-based functional group are located in the branch chain

(Meth) acrylate-based (co) polymer, or a precursor thereof, a coating film or a coating film is formed from the photopolymer composition 2019/112358 1 »(: 1 ^ 1 {2018/015467

The crosslink density is optimized during the manufacture of the hologram, which ensures excellent durability against temperature and humidity compared to conventional matrices. In addition, through the above-mentioned crosslinking density optimization, the recording property can be improved by maximizing the refractive index modulation by increasing the fluidity ₁₁₁₀ 1 between the photoreactive monomer having a high refractive index and the component having a low refractive index.

 Particularly, a crosslinked structure mediated by a siloxane bond can be easily introduced through a sol-gel reaction between a modified (meth) acrylate-based (co) polymer containing a silane-based functional group and a silane crosslinking agent containing a terminal silane- , Such siloxane bonds can provide excellent durability against temperature and humidity.

 The (meth) acrylate-based (co) polymer and the silane crosslinking agent in which the above-mentioned silane-based functional group is located on the branch chain in the polymer matrix may be present as separate components, and also exist in the form of a complex can do.

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

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

 The silane crosslinking agent may be a compound having an average of at least one silane-based functional group per molecule or a mixture thereof, and may be a compound containing at least one silane-based functional group. The silane-based functional group may include a silane functional group or an alkoxysilane functional group, and preferably a triethoxysilane group may be used as an alkoxysilane functional group. The silane-

(Co) polymer and silane crosslinking agent can be crosslinked by forming a siloxane bond through a sol-gel reaction with a silane-based functional group contained in the (meth) acrylate-based (co) polymer.

At this time, the silane crosslinking agent has an equivalent equivalent of the silane-based functional group of 200 1000 g / piece. Accordingly, the cross-linking density between the (meth) acrylate-based (co) polymer and the silane cross-linking agent is optimized, and excellent durability against temperature and humidity can be secured compared to the existing matrix. In addition, through the above-mentioned optimization of the crosslink density, the recording property can be improved by maximizing the refractive index modulation by increasing the mobility between the photoreactive monomer having a high refractive index and the component having a low refractive index.

 If the equivalence of the silane-based functional groups contained in the silane crosslinking agent is excessively increased to 1000 g / mol or more, the diffraction grating interface after recording may be broken due to the reduction of the crosslinking density of the matrix, and the loose crosslinking density and the glass transition temperature The monomer and plasticizer components can be eluted to the surface to generate haze. If the equivalent of the silane-based functional group contained in the silane crosslinking agent is excessively decreased to less than 200 g / g, crosslinking density becomes too high, which hinders the flowability of the monomer and the plasticizer components, .

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

 The linear polyether backbone having a weight average molecular weight of 100 to 2000 may include a repeating unit represented by the following formula (3).

 (3)

 - (R5S

 And n is an integer of 1 or more, or 1 to 50, or 5 to 20, or an integer of 8 to 10. The term " alkylene group "

 The silane crosslinking agent can introduce a flexible polyether polyol as a main chain to improve the fluidity of the components by controlling the glass transition temperature and crosslinking density of the matrix.

On the other hand, the bond between the silane functional group and the polyether backbone may be mediated by a urethane bond. Specifically, the silane-based functional group and the polyether main chain may form a mutual bond through a urethane bond, more specifically, a silicon atom contained in the silane-based functional group may be bonded directly to the nitrogen atom of the urethane bond 2019/112358 1 »(: 1 ^ 1 {2018/015467

An alkylene group having 1 to 10 carbon atoms, and the functional group contained in the polyether backbone can be bonded directly to the oxygen atom of the urethane bond.

 The reason why the silane-based functional group and the polyether main chain are bonded through the urethane bond is that the silane crosslinking agent is produced through a reaction between an isocyanate compound containing a silane functional group and a linear polyether polyol compound having a weight average molecular weight of 100 to 2000 Lt; / RTI >

 More specifically, the isocyanate compound is an aliphatic, cycloaliphatic, aromatic or aromatic aliphatic mono-isocyanate di-isocyanate, tri-isocyanate or poly-isocyanate; Or oligo- isocyanates of diisocyanates or triisocyanates having urethane, urea, carbodiimide, acyl urea, isocyanurate, allophanate, biuret, oxadiazinetrione, uretdione or iminooxadiazine dione structures Or poly-isocyanate.

 Specific examples of the isocyanate compound containing the silane functional group include 3-isocyanatopropyltriethoxysilane.

 Also, the polyether polyol may be, for example, a polyaddition product of styrene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin, mixed adducts and graft products thereof, And polyether polyols and polyhydric alcohols obtained by condensation of polyhydric alcohols or mixtures thereof, amines and amino alcohols.

 Specific examples of the polyether polyol include a number average molecular weight of between 0.01 and 10, a number average molecular weight of between 200 and 18000 y / mole, preferably a functionality of 011 of from 1.8 to 4.0 and a number average molecular weight of 600 to 8000 / , Particularly preferably from 1.9 to 3.1. Poly (propylene oxide), poly (ethylene oxide), and combinations thereof, or poly (tetrahydrofuran) and combinations thereof, having a number average molecular weight of from 5,000 to 5,000 yuan / ≪ / RTI >

 As described above, when the silane functional group and the polyether main chain are bonded via a urethane bond, a silane crosslinking agent can be more easily synthesized.

The weight average molecular weight of the silane crosslinking agent is measured in a range of 1,000 to 5,000,000 days . The weight average molecular weight means the weight average molecular weight (unit: g / mol) in terms of polystyrene measured by GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, a detector such as a known analyzer and a refractive index detector may be used, and a column for analysis may be used. Temperature conditions, solvent, and f low rate. Specific examples of the measurement conditions include a temperature of 30 ° C, a chloroform solvent (Chloroform), and an f low rate of 1 mL / min.

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

 Examples of the (meth) acrylate repeating unit in which the silane functional group is located in the branch chain include repeating units represented by the following formula (1).

 [Chemical Formula 1]

 In the above formula (1), each of ¾ to ¾ is independently an alkyl group having 1 to 10 carbon atoms, ¾ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and ¾ is an alkylene group having 1 to 10 carbon atoms.

Preferably, in the above formula (1), each of I to ₃ is independently a methyl group having a carbon number of 1, a methyl group having a carbon number of 1 or 3, and a propylene group having a carbon number of 3 /

Derived unit,

Each of which is independently a methyl group with a carbon number of 1, a hydrogen atom with a hydrogen atom, and a propylene group with a carbon number of 3,

Lt; / RTI > repeat unit.

Examples of the (meth) acrylate repeating unit include And a repeating unit to be displayed.

 (2)

In the above formula (2), ¾ is an alkyl group having 1 to 20 carbon atoms, R ₇ is hydrogen or an alkyl group having 1 to 10 carbon atoms, preferably 3 or 4 carbon atoms, and R ₇ is hydrogen , And a repeating unit derived from butyl acrylate.

 The molar ratio of the repeating unit of Formula 2 to the repeating unit of Formula 1 may be 0.5: 1 to 14: 1. If the molar ratio of repeating units of formula (1) is excessively decreased, the cross-linking density of the matrix becomes too low to serve as a support, resulting in a decrease in recording characteristics after recording, , The crosslinking density of the matrix becomes too high and the fluidity of the respective components may be deteriorated, resulting in a decrease in the refractive index modulation value.

 The weight average molecular weight (GPC measurement) of the (meth) acrylate-based (co) polymer is

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 GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, a detector such as a known analyzer and a refractive index detector may be used, and a column for analysis may be used. Temperature conditions, solvent, and f low rate. Specific examples of the measurement conditions include a temperature of 30 ° C., a chloroform solvent (Chloroform), and an f low rate of 1 mL / min.

On the other hand, the (meth) acrylate-based (co) polymer is preferably a 2019/112358 1 »(: 1 ^ 1 {2018/015467

Equivalent weight 300 _§ / one to 2000 g / 7 ^ or 500

To 2000

, Or from 550 to 1800 Y / dog, or from 580 to 1600

Or 586 _§ / number to 1562. The equivalent weight means the average molecular weight between the silane functional groups. The smaller the equivalent value, the higher the functional group density. The larger the equivalent value, the smaller the functional group density.

Accordingly, the cross-linking density between the (meth) acrylate-based (co) polymer and the silane cross-linking agent is optimized, thereby ensuring excellent durability against temperature and humidity compared to the existing matrix. In addition, through the above-mentioned crosslinking density optimization, the recording property can be improved by maximizing the refractive index modulation by increasing the fluidity (1) between the photoreactive monomer having a high refractive index and the component having a low refractive index. ^'

 If the equivalence of the silane-based functional group contained in the (meth) acrylate-based (co) polymer is excessively reduced to less than 300 / s, the crosslinking density of the matrix becomes too high to inhibit the flowability of the components, May occur. Also, if the equivalent of the silane-based functional group contained in the (meth) acrylate-based (co) polymer is excessively increased to over 2,000 / unit, the crosslinking density becomes too low to serve as a support, The refractive index modulation value can be reduced over time as the interface of the diffraction gratings collapses.

 The silane crosslinking agent may be used in an amount of 10 to 90 parts by weight, 20 to 70 parts by weight, or 22 to 65 parts by weight based on 100 parts by weight of the (meth) acrylate-based (co) polymer. have.

 In the reaction product, if the silane crosslinking agent content is excessively decreased with respect to 100 parts by weight of the (meth) acrylate-based (co) polymer, the curing rate of the matrix is significantly slowed to lose its function as a support, Can easily collapse, and in the reaction product,

If the amount of the silane crosslinking agent is excessively increased relative to 100 parts by weight of the (meth) acrylate-based (co) polymer, the curing rate of the matrix is increased, but the compatibility of the components with other components is increased due to an excessive increase of the reactive silane group content And haze is generated. The modulus (storage elastic modulus) of the reaction product may be 0.01 MPa to 5 MPa. As a specific example of the modulus measuring method,

A storage modulus (G ') value can be determined at a frequency of 1 Hz at room temperature (20 ° C to 25 ° C) using a DHR (di scover hybr idometer) instrument. The glass transition temperature of the reaction product may be from -40 ° C to 10 ° C. As a specific example of the glass transition temperature measuring method, a 0.1% strain is measured using a DMA (dynami c mechanic cal analys) , frequency 1 Hz, heating rate

And a method of measuring a change in the phase angle (loss modulus) of a film coated with the photopolymerizable composition in the range of -80 ° C to 30 ° C under the setting condition of 5 ° C / min. Another example of the polymer matrix or its precursor is a polymer matrix comprising the reaction product of a compound containing at least one isocyanate group and a polyol.

 The compound containing at least one isocyanate group may be a known compound having at least one NCO functional group per molecule or a mixture thereof and may be a compound containing at least one isocyanate group.

More specifically, the compound containing at least one isocyanate group is an aliphatic _, cycloaliphatic, aromatic or aromatic aliphatic mono-di-, tri- or poly-isocyanate. In addition, compounds containing a group the at least one isocyanate is a urethane, urea, carbodiimide, acyl urea, isocyanurate, allophanate, biuret, oxadiazolyl Ghintec Leone _and right inlet-dione or already monomer having a nook Saadi-triazine-dione Structure (Oligo- and polyisocyanates) of relatively high molecular weight of di- and / or triisocyanates.

Specific examples of the compound containing at least one isocyanate group include at least one compound selected from the group consisting of butylene diisocyanate, hexylene methylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 1,8-diisocyanato-4- (isocyanatomethyl ) Octane, 2,2,4 - and / or 2,4,4-trimethylnucleomethylene diisocyanate, isomeric bis (4,4'-isocyanatocyclohexyl) methane and any desired isomers 2019/112358 1 »(: 1 ^ 1 {2018/015467

1, 4-cyclohexane diisocyanate, isomeric cyclohexane dimethylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-diisocyanate, 1,4-cyclohexane diisocyanate, - and / or 2,6-toluene diisocyanate, 1,5-naphthylene diisocyanate, 2,4'- or 4,4'-diphenylmethane diisocyanate and / or triphenylmethane. 4,4 ', 4 "-Triisocyanate, and the like.

 The polyol which reacts with the compound containing at least one isocyanate group to form a polymer matrix may be an aliphatic, aromatic aliphatic or cycloaliphatic diol, triol and / or higher polyol having 2 to 20 carbon atoms.

The polyol is 300

Lt; RTI ID = 0.0 > 10,000 < / RTI >

May have a weight average molecular weight.

 Examples of the diols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl But are not limited to, glycols, 2-ethyl-2-butylpropanediol, trimethylpentanediol, diethyloctanediol positional isomers, 1,3-butylene glycol, , 2, 2-dimethyl-3-hydroxypropyl, dimethyl-3- (2-methyl- And hydroxypropionate.

 Examples of the triols include trimethylolethane, trimethylolpropane or glycerol. Suitable highly-functional alcohols are ditrimethylolpropane, pentaerythritol, dipentaerythritol or sorbitol.

 The polyols also include aliphatic and cycloaliphatic polyols of relatively high molecular weight such as polyester polyols, polyether polyols, polycarbonate polyols, hydroxy-functional acrylic resins, hydroxy-functionalized urethanes, hydroxy- Functional epoxy resin and the like can be used.

The polyester polyol may be, for example, ethanediol, di-, tri- or tetraethylene glycol, 1,2-propanediol, di-, tri- or tetrapropyleneglycol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-nucleic acid diol, 2,2- 2019/112358 1 »(: 1 ^ 1 {2018/015467

Polyhydric alcohols such as dihydroxycyclo- nucleic acid, 1,4-dimethylolcyclo-nucleic acid, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol or mixtures thereof, and optionally trimethyl It is also possible to use higher functionality polyols, such as olpropane or glycerol, at the same time, for example, in the presence of a catalyst such as succinic acid, glutaric acid, adipic acid, pimelic acid, Aliphatic, such as terephthalic acid, terephthalic acid, isophthalic acid, _0- phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid or trimellitic acid and acid anhydrides such as _0- phthalic anhydride, trimellitic anhydride or succinic anhydride, , Linear aliphatic or aromatic di- or polycarboxylic acids or anhydrides thereof, such as those which can be prepared in a known manner, . Of course, di- and polyhydroxy compounds of cyclic aliphatic and / or aromatic are also suitable as polyhydric alcohols for the preparation of polyester polyols. Instead of free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic anhydrides of the lower alcohols or the corresponding polycarboxylates, or mixtures thereof, in the preparation of the polyesters.

Also, the polyester polyol that can be used in the synthesis of the polymer matrix is one of a lactone - are or with the copolymer, which preferably butyrolactone, _£ _-caprolactone and / or methyl - _£ - lactone, such as caprolactone Or lactone mixture with a suitable bifunctional and / or higher functional initiator molecule, such as the above-mentioned small molecular weight polyhydric alcohol, for example as a synthetic component for polyester polyols.

 The polycarbonate having a hydroxyl group is also suitable as a polyhydroxy component for prepolymer synthesis, for example, a diol such as 1,4-butanediol and / or 1,6-nucleic acid diol and / or 3-methyl For example, by reaction of pentanediol with diaryl carbonates such as diphenyl carbonate, dimethyl carbonate or phosgene.

The polyether polyol which can be used for the synthesis of the polymer matrix may be, for example, a polyaddition product of styrene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide and epichlorohydrin, Mixed adducts and graft products, and polyhydric alcohols or their Those obtained by alkoxylation of polyether polyols and polyhydric alcohols, amines and amino alcohols obtained by condensation of the mixture. Specific examples of the polyether polyols include OH functionalities of 1.5 to 6 and number average molecular weights of 200 to 18000 g / mole, OH functionalities of preferably 1.8 to 4.0 and number average molecular weights of 600 to 8000 g / mole, Poly (propylene oxide) in the form of random or block copolymers, poly (ethylene oxide) and combinations thereof, having an OH functionality of 1.9 to 3.1 and a number average molecular weight of 650 to 4500 g / mol, Or poly (tetrahydrofuran) and mixtures thereof. On the other hand, the photoreactive monomer may include a polyfunctional (meth) acrylate monomer or a monofunctional (meth) acrylate monomer.

 As described above, in the photopolymerization of the photopolymer composition, the monomer is polymerized to increase the refractive index at a portion where a relatively large amount of polymer is present, and at a portion where a polymer binder is relatively present, the refractive index is relatively low, , And the diffraction grating is generated by such refractive index modulation.

 Specifically, examples of the photoreactive monomer include (meth) acrylate type a, p-unsaturated carboxylic acid derivatives such as (meth) acrylate,

(Meth) acrylamide, (meth) acrylonitrile or (meth) acrylic acid, or a compound containing a vinyl group or a thiol.

 One example of the photoreactive monomer is 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 monomers may include halogen atoms (bromine, iodine, etc.), sulfur (S), phosphorus, or aromatic rings.

More specific examples of the polyfunctional (meth) acrylate monomer having a refractive index of 1.5 or more include bi sphenol A modi fi ed diacrylate series, fuorene acrylate series (HR 6022 - Miwontt), bi sphenol fuorene epoxy aery late series (HR6100, HR6060, HR6042, etc. - Miwonf soil), Halogenated epoxy acrylate series (HR1139, HR3362, etc., Miwon _/ tt).

 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 in the molecule. Specific examples of the monofunctional (meth) acrylate monomer include phenoxybenzyl

(Meth) acrylate, _0-phenyl phenol ethylene oxide (meth) acrylate, benzyl (meth) acrylate, 2- (phenyl sayi oh) ethyl (meth) acrylate or biphenyl (meth) acrylate Can be heard.

 On the other hand, the photoreactive monomer may have a weight average molecular weight ranging from 50 g / mol to 1000 g / mol, or from 200 g / mol to 600 g / m. The weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by GPC method. Meanwhile, the hologram recording medium of the embodiment may further include a photoinitiator. The photoinitiator is a compound which is 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, conventionally known photoinitiators may be used without any limitation, and specific examples thereof include a photo radical polymerization initiator, a photo cationic polymerization initiator, and a photoanion polymerization initiator.

Specific examples of the photoradical polymerization initiator include imidazole derivatives, bisimidazole derivatives, N-aryl glycine derivatives, organic azide compounds, titanocene, aluminate complexes, organic peroxides, N-alkoxypyridinium salts, Derivatives, and amine derivatives. More specifically, examples of the photocatalytic polymerization initiator include 1,3-di (t-butyldioxycarbonyl) benzophenone, 3,3 ', 4,4' tetrax (t-butyldimethylbenzyl) benzophenone, 3 phenyl-5-i soxazo 1, 2-mercapto benzimidazole, bi 2, 4, 5-tr ipheny 1 imidazole, (Product name: Irgacure 184 / manufacturer: BASF), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (product name: Irgacure 651 / manufacturer: BASF) : Irgacure 369 / Manufactured by BASF), and bis (r _{| 5} -2, 4-o e 1 opent ad i ene-1-yl) -bis (2,6-difluoro-3-

(Product name: Irgacure 784 manufactured by BASF), Ebecryl P-115 (manufactured by SK Industries), and the like.

Examples of the photocationic polymerization initiator include diazonium salts, sulfonium salts, and iodonium salts, and examples thereof include sulfonic acid esters, imidosulfuric acid esters, carbonate, di-alkyl-4-hydroxyphenyl sulfonium salts, aryl ^sulfonate-_ p-nitrobenzyl ester, silanol-aluminum complex, (r _{| 6} ^_ benzene)

(R- ₅ -cyclopentadienyl) iron (II), and the like. In addition, benzoin tosylate,

2,5-dinitrobenzyl tosylate, N-tosyl phthalimide and the like. More specific examples of the photocationic polymerization initiator include Cyracure UVI-6970, Cyracure

UVI-6974 and Cyracure UVI-6990 (manufactured by Dow Chemical Co.). in USA), Irgacure 264 and Irgacure 250 (manufacturer: BASF) or CIT-1682

(Manufacturer: Nippon Soda) and the like.

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

 In addition, the photopolymer composition of the above-mentioned examples may use one molecule (type I) or two molecules (type I I) initiator. The (Type I) system for the free radical photopolymerization is, for example, an aromatic ketone compound combined with a tertiary amine such as benzophenone, alkylbenzophenone, 4, -bis (dimethylamino) benzophenone (Michler's ketone ), Anthrone and halogenated benzophenone or mixtures of the above types. The bis (type II) initiators include benzoin and derivatives thereof, benzyl ketal, acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bisacylphosphine oxide, phenylglycine Alpha-aminoalkylacetophenone, 1- [4- (phenylthio) phenyl] octane-1,2-dione 2- (0-benzoyloxime) and alpha -Hydroxyalkylphenone, and the like.

The hologram recording medium of this embodiment may be a polymer matrix, 1% to 80% by weight of the precursor; 1% to 80% by weight of the photoreactive monomer; And 0.1% to 20% by weight of a photoinitiator. As will be described later, when the photopolymer composition further comprises an organic solvent, the content of the above-mentioned components is based on the total of these components (the sum of the components excluding the organic solvent). The hologram recording medium may further include at least one selected from the group consisting of a phosphate compound and a low refractive index fluorine compound.

 The phosphate compound and the low refractive index fluorine compound have a lower refractive index than the photoreactive monomer, thereby lowering the refractive index of the polymer matrix, thereby maximizing the refractive index modulation of the photopolymer composition. In addition, the phosphate compound acts as a plasticizer to lower the glass transition temperature of the polymer matrix to increase the mobility of the photoreactive monomer and the low refractive index, and to contribute to the improvement of the moldability of the photopolymer composition have.

More specifically, since the low refractive index fluorine-based compound has stability with little reactivity and has a low refractive index, the refractive index of the polymer matrix can be lowered when added to the photopolymer composition, thereby maximizing the refractive index modulation with the monomer . * ₁₁₀ The fluorine-based compound 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 represented by the following formula (4) in which a functional group including an ether group is bonded to both terminals of a central functional group including a direct bond or an ether bond in two difluoromethylene periods.

 [Chemical formula 4] 7 \ 14 JR /

Rii, 0, f, f < _18, wherein R _n and R ₁₂ are each independently 2019/112358 1 »(: 1 ^ 1 {2018/015467

Is methyl tengi difluoromethyl, and 1½ mitmyo ₁₆ is methyl tengi, each independently, a methylene group to ¾ ₄ and each independently represents difluoromethyl, ¾ ₇ and ₈ are each independently a polyalkylene oxide group, is greater than or equal to 1, Or an integer from 1 to 10, or from 1 to 3.

Preferably, in Formula 4,

And ¾ ₂ is methyl tengi difluoro, each independently, is ₃ ¾ and ¾ ₆ is methyl tengi, each independently, a 1? _14, and ₁₅ are each independently a difluoromethylene group, and ¾ ₇ and

Each independently represents 2-methoxyethoxymethoxy group, and ??? ₁ is an integer of 2.

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

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

 If the content of the fluorine-based compound is excessively decreased with respect to 100 parts by weight of the photoreactive monomer, the refractive index modulation value after recording is lowered due to the lack of the low refractive index, and the content of the fluorine-based compound is excessively increased with respect to 100 parts by weight of the photoreactive monomer , There may arise haze due to compatibility with other components or a problem that some fluorine compounds are eluted to the surface of the coating layer.

 The fluorine-based compound may have a weight average molecular weight of about 300 or more, or about 300 to about 1,000. A specific method of measuring the weight average molecular weight is as described above.

 Specific examples of the phosphate compound include triphenyl phosphate, tricresyl phosphate, cresyldiphenyl phosphate, octyldiphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

The phosphate-based compound together with the fluorine-based compound described above may be used in a ratio of 1: 5: 1. &Lt; / RTI &gt; The phosphate compound may have a refractive index of less than 1.5 and a molecular weight of 700 or less. The hologram recording medium may further include a photosensitive dye. The photosensitive dye acts as an enhancer for increasing or decreasing the photoinitiator. More specifically, the photosensitive dye is stimulated by light irradiated to the photopolymer composition to serve as an initiator for initiating the polymerization of the monomer and the crosslinking monomer can do. The photopolymer composition may comprise from 0.01% to 30%, or from 0.05% to 20% by weight of the photosensitive dye.

 The examples of the photosensitive dye are not limited to a wide variety, and a variety of commonly known compounds can be used. Specific examples of the photosensitive dye include a sulfonium derivative of ceramidonine, sul fonium der ive ive, new methylene blue, thioerythrosine triethylammonium, 6-acetylamino- Methyl ceramidonin, eosin, erythros ine, rose bengal, thionine, basic yellow, and the like. Rhodamine 6G, gal locyanine, ethyl violet, Victoria blue R, Celest ine blue, and the like. Quillidine Red, Crystal Violet, Brilliant Green, Astrazon orange G, darrow red, pyronin Y, Basic red 29, pyrilium Kpyryl i um iodide, KSafranin 0, cyanine, methylene blue, Azure A, or a combination of two or more thereof. An organic solvent may be used in the production of the hologram recording medium. Non-limiting examples of the organic solvent include ketones, alcohols, acetates and ethers, and mixtures of two or more of them.

Specific examples of such an organic solvent include ketones such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone or isobutyl ketone; Methanol, ethanol, n-propanol, 2019/112358 1 »(: 1 ^ 1 {2018/015467

Alcohols such as propanol, ₁₁ -butanol, butanol, and butanol; Ethyl acetate, propyl acetate, or polyethylene glycol monomethyl ether acetate; Ethers such as tetrahydrofuran or propylene glycol monomethyl ether; Or mixtures of two or more thereof. The organic solvent may be added to the photopolymer composition at the time of mixing the components contained in the photopolymer composition for producing the hologram recording medium, or may be added to the photopolymer composition while the components are dispersed or mixed in the organic solvent. If the content of the organic solvent in the photopolymer composition is too small, the flowability of the photopolymer composition may be deteriorated, resulting in defects such as streaks in the finally produced film. In addition, when the organic solvent is added in an excess amount, the solid content is lowered, and the coating and film formation are not sufficiently performed, so that the physical properties and surface characteristics of the film may be deteriorated and defects may occur during the drying and curing process. Accordingly, the photopolymer composition may comprise an organic solvent such that the concentration of the total solids of the components contained is from 1 wt% to 70 wt%, or from 2 wt% to 50 wt%.

The photopolymer composition may further include other additives, a catalyst, and the like. For example, the photopolymer composition may comprise a catalyst commonly known for promoting polymerization of the polymer matrix or light-reactive monomer. Examples of the catalyst include tin octanoate, zinc octanoate, dibutyltin dilaurate, dimethyl bis [(1-oxoneodecyl) oxy] stannane, dimethyl tin dicarboxylate, zirconium bis I) -toluenesulfonic acid ( _{1) -1} : ₀ 1 _116116311 1 _{0 011 801 (} 1) or a tertiary amine such as 1,4-diazabicyclo [2.2.2] octane 1, 3-tetramethylguanidine, 1, 3, 4, 6, 7, 8-Nucleic acid hydro-1-methyl-pyrimido (1,2) Pyrimidine and the like.

Examples of the other additives include a defoaming agent, and the defoaming agent may be a silicone-based reactive additive. Examples of the defoaming agent include 1 6 ₀ 0 1 (1 2500). Even at thickness of 30 _ 0.020 2019/112358 1 »(: 1 ^ 1 {2018/015467

Or 0.021 or more, or a refractive index modulation value of 0.020 to 0.035).

Further, the hologram recording medium may be implemented to 5 _/ Fe - 30 _ the diffraction efficiency of 50% or more in thickness, or less than 85%, or 85 to 99%.

 The photopolymer composition for producing the hologram recording medium is prepared by homogeneously mixing the respective components contained therein and drying and curing at a temperature of 20 ° C or higher. Thereafter, the photopolymer composition is subjected to a predetermined exposure process to form an entire visible region and a near- RTI ID = 0.0 &gt; 300-800. &Lt; / RTI &gt;

 In the photopolymer composition, the polymer matrix or the precursor-forming component thereof may first be uniformly mixed, and the silane crosslinking agent may be mixed with the catalyst to prepare a process for forming a hologram.

The photopolymer composition may be mixed with any of the components of the photopolymer composition without any limitations, such as a mixer, a stirrer, or a mixer,

To 100 [deg.] (1, preferably

(Preferably from 10 to 80, more preferably from 20 to 60).

 On the other hand, in the photopolymer composition, the polymer matrix or its precursor-forming component may first be homogeneously mixed and then a liquid formulation which is cured at a temperature of 20 ° C or higher. 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 ° to 180 ° C.

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

On the other hand, a method of recording a visual hologram on a hologram recording medium manufactured from the photopolymer composition can use a conventionally known method without any limitation, and adopts the method described in the holographic recording method of the embodiment to be described later as an example can do. On the other hand, according to another embodiment of the invention, a holographic recording method may be provided, which comprises selectively polymerizing the photoreactive monomer contained in the photopolymer composition by a coherent laser.

 As described above, by mixing and curing the photopolymer composition, a medium in a state in which no visual hologram is recorded can be manufactured, and a visual hologram can be recorded on the medium through a predetermined exposure process. A visual hologram can be recorded on media provided through the process of mixing and curing the photopolymer composition, using known devices and methods under commonly known conditions. On the other hand, according to another embodiment of the invention, an optical element including a hologram recording medium can be provided.

 Specific examples of the optical element include an optical lens, a mirror, a deflecting mirror, a filter, a diffusing screen, a diffraction member, a light guide, a waveguide, a holographic optical element having a function of a projection screen and / A diffusion plate, a light wavelength splitter, a reflection type, and a transmission type color filter.

 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 irradiates a laser beam used for providing, recording, and reproducing three-dimensional image information of an object in an input unit and a display unit. In addition, the input unit pre-inputs three-dimensional image information of an object to be recorded on the display unit. For example, the input unit may be provided with an electric driving liquid crystal SLM (electric addressed lid crystal SLM) Three-dimensional information of an object can be input, and an input beam can be used at this time. The optical system may include a mirror, a polarizer, a beam splitter, a beam shutter, a lens, and the like. The optical system includes an input beam for transmitting a laser beam emitted from a light source unit to an input unit, a recording beam for sending to a display unit, The beam can be distributed by the beam.

The display unit receives the three-dimensional image information of the object from the input unit and transmits the three-dimensional image information to the hologram plate made of an optically driven SLM 2019/112358 1 »(: 1 ^ 1 {2018/015467

And reproduce a three-dimensional image of the object. At this time, the three-dimensional image information of the object can be recorded through the interference of the input beam and the reference beam. The three-dimensional image information of the object recorded on the hologram plate can be reproduced as a three-dimensional 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 can be moved between a position for inputting the 3D image and a position for reproducing the 3D image.

 【Effects of the Invention】

 According to the present invention, it is possible to provide a hologram recording medium having a thin thickness, a large refractive index modulation value and improved durability against temperature and humidity, an optical element including the same, and a holographic recording method using the hologram recording medium.

 DETAILED DESCRIPTION OF THE INVENTION

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

[Manufacturing Example]

 Production Example 1: Synthesis of polyol

Of methyl acrylate 34.5 _부 , butyl acrylate 57.5 _,, 4-hydroxybutyl acrylate

Flask, and diluted with ethyl acetate 150 _§. Stirring was continued for about 1 hour while maintaining the temperature of the jacket reactor at 60 to 70 [deg.]. Then, 0.035 part of ₁₁ -dodecyl mercaptan was further added to the reactor, and further stirring was continued for about 30 minutes. Then,

0.04 was added, and the polymerization was continued for about 4 hours at a temperature of about 70 [deg.] To maintain the residual acrylate monomer content to 1 wt%, thereby synthesizing a polyol. At this time, the weight average molecular weight of the obtained polyol in terms of polystyrene measured by the method was about 700,000, and the amount per square meter measured by the titration method was 1802 _{ง 811111} . Production Example 2: Preparation of bivalent low refractive material 2

 To a 1000 ml flask was added 2,2 '- ((oxybis (1,1,2,2-tetrafluoroethane-2,1-diyl) bis (oxy) The mixture was stirred at 0 ° C and sodium hydride (60% di-spore in mineral oil) for 4 minutes was added carefully several times. The mixture was stirred at 0 ° C After 20 minutes of inoculation, 12.50 ml of 2-methoxyethoxyethane was added dropwise. When it was confirmed that all the reactants were consumed by ¼ NMR, the reaction solvent was all removed by decompression. The organic layer was collected by extraction with 300 g of dichloromethane three times. The organic layer was collected by filtration with magnes ium sul fate and then decompressed to remove all the dichloromethane to obtain 29 g of a liquid product having a purity of 95% or more at a yield of 98%. Preparation Example 3: Preparation of (meth) acrylate-based (co) polymer having silane functional group in the branch chain

21 jacket reactor was charged with 69.3 parts of butyl acrylate, 20.7 parts of ^ -503 (3-methacryloxypropyltrimethoxysilane), and diluted with 70/4 of ethyl acetate. The reaction temperature was set at about 70 ° C and stirred for about 1 hour. ₁₁ -dodecyl mercaptan (0.02 _을) was further added, and the mixture was further stirred for 30 minutes. Thereafter, 0.06 _§ of a polymerization initiator was added and the polymerization was continued for 4 hours or more at the reaction temperature to maintain the residual acrylate content until the residual acrylate content became less than 1% to obtain a (meth) acrylate-based Co) polymer

(Weight average molecular weight: about 900,000, ^ _ (010 ₃ equivalents: 1019 _§ / number). Production Example 4: Preparation of silane crosslinking agent

1000 ₁₁₁ -9007 in Table 1, flasks? - Put (3 isocyanato propyl triethoxysilane) 19.79 _§, £ 0-400 12.80 ₃ and射此_§ 0.57, it was diluted with tetrahydrofuran 30½. The reaction mixture was stirred at room temperature until it was confirmed that all the reactants were consumed, and then the reaction solvent was removed by decompression.

Under a developing solution of dichloromethane: methyl alcohol = 30: 1, Separating the liquid product 28 ₂ purity of at least 95% via chromatography with 91% yield to give a silane cross-linking agent.

[Examples and Comparative Examples: Production of photopolymer composition]

 Examples 1 &amp; 2 &amp;

 The polyol, photoreactive monomer (high refractive index acrylate, refractive index 1.600, HR6022 [Miwon]), safranin 0 (dye, manufactured by Sigma Aldrich), non-reactive low refractive material of Production Example 2, tributyl phosphate (ibid), Irgacure 250 (BASF), and methyl isobutyl ketone (MIBK) were added to the reaction mixture. And the mixture was stirred with a Paste mixer for about 10 minutes to obtain a clear coating solution.

 To the coating solution, MFA-75X (Asahi Kasei, hexafunctional isocyanate, diluted to 75 wt% in xylene) was added, and the mixture was further stirred for 5 to 10 minutes. DBTDLCdibutyl tin diurate as a catalyst was added thereto and stirred for about 1 minute Using a Meyer bar, 80 / M thick

Cycled to TAC substrate 7 and cured at 40 ° C for 1 hour. Examples 3 and 4

 (Meth) acrylate (co) polymer, photoreactive monomer (high refractive index acrylate, refractive index 1.600, HR 6022 [Mi Won]) in which the silane functional group of the preparation example 3 was placed in the branch chain, (Dibutylglycine), Ebecryl P-115 (SK ent), and triphenylphosphine of Example 2, tributyl phosphate (TB ibutyl phosphate [TBP], molecular weight 266.31, refractive index 1.424, Sigma Aldrich) was mixed with a Borate V (Spectra group), Irgacure 250 (BASF) and methyl isobutyl ketone (MIBK) in a light shielding state, and stirred with a Paste mixer for about 10 minutes to obtain a transparent coating liquid.

The silane crosslinking agent of Preparation Example 4 was added to the coating solution and further stirred for 5 to 10 minutes. Then, the catalyst DBTDL was added to the coating solution, After stirring, the coating was coated on a TAC substrate of 80 / M in thickness by using a meyer bar and dried at 40 ° C for 1 hour.

[Experimental Example: Holographic Recording]

 (1) The photopolymer (hologram recording medium) coated surface prepared in each of the above Examples and Comparative Examples was laminated to s1-ide glass, and during recording, the laser was fixed so as to pass through the glass surface first.

(2) Measurement of main relaxation temperature (Tr) using DMA

 The temperature was set to -80 ° C to 30 ° C with the use of a DMA (dynami c mechani cal analys) equipment with a strain of 0.1%, a frequency of 1 Hz and a heating rate of 5 ° C / min. In the C region, the phase angle of the hologram recording medium before recording was measured in a film state.

 The phase angle is the angular value of tan del ta calculated by G "(loss modulus) / G '(strorage modulus), and the larger the phase angle value, the higher the vi scous characteristic of the material do.

 The point at which the rate of change of the phase angle with temperature was largest was defined as the main relaxation temperature and the Tr value of the hologram recording medium obtained in the examples and the comparative examples was confirmed.

(3) Diffraction efficiency (n) measurement

 A holographic recording was made through interference of two interfering lights (reference light and object light), and the transmissive recording made the two beams incident on the same side of the sample. The diffraction efficiency is changed according to the incident angle of the two beams, and when the incident angles of the two beams are the same, the beam becomes non-santed. The non-slanted recording is generated perpendicular to the film, since the incident angles of the two beams are normalized.

(20 = 45 °) using a laser of 532 nm wavelength and a transmission type non-slanting method, and the diffraction efficiency () was calculated by the following general formula (1). [Formula 1]

In the above general formula ( ₁₎ ,? Is the diffraction efficiency, and ₁₎ represents the output amount 0 # / 0! Of the diffracted beam of the sample after recording. ₁ ), and is the output amount 0 # / 0 ₁₁ of the transmitted beam of the recorded sample.

(4) Measurement of refractive index modulation value (n)

 Lossless Dielectric Grating of Transmissive Hologram The refractive index modulation value (An) can be calculated from the general formula (2).

[Formula 2]

In the general formula 2, 1 is the thickness of the photopolymer layer, ₁ is a refractive index modulation value,? Is a diffraction efficiency, and} is a recording wavelength.

[Table 1] Photopolymer composition (unit:) of the examples and experimental results of the holographic recording medium produced therefrom Measurement results

 ** Non-reactive plasticizer: Tributyl phosphate (Molecular Weight 266.31, refractive index 1.424, purchased from Sigma-Aldrich) As shown in Table 1 above, a dynamic mechanical analysis in the region of -80 ° C to 30 ° C The main relaxation temperature (Tr), which is the point where the rate of change of the phase angle with temperature is largest,

It was confirmed that the hologram recording media of Examples 1 to 4 having a temperature of 0 ° C or less can realize a refractive index modulation value (An) of 0.024 or more. On the other hand, it was confirmed that the hologram recording medium of Comparative Example 1 in which the Tr was 13 ° C had a relatively low diffraction efficiency as compared with the Example.

Claims

Claims:

 [Claim 1]

 In the dynami c mechanical analysis at -80 ° C to 30 ° C, the main relaxation temperature, which is the point at which the rate of phase angle change with temperature changes, is below 0 ° C Lt; / RTI &gt;

[Claim 2]

 The method according to claim 1,

 The kinetic analysis was carried out at conditions of a strain of 0.1%, a frequency of 1 Hz and a heating rate of 5 ° C / min. The hologram recording medium

[Claim 3]

 The method according to claim 1,

 Wherein the hologram recording medium comprises a polymer matrix or a precursor thereof; And a photoreactive monomer.

[4]

 The method of claim 3,

 Wherein the hologram recording medium further comprises a photoinitiator.

[Claim 5]

 The method of claim 3,

Wherein the hologram recording medium further comprises at least one member selected from the group consisting of a phosphate compound and a low refractive index fluorine compound. 2019/112358 1 »(: 1 ^ 1 {2018/015467

[Claim 6]

 6. The method of claim 5,

 Wherein the low refractive index fluorine-based compound comprises 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.

7.

 6. The method of claim 5,

 Wherein the low refractive index fluorine compound has a refractive index of less than 1.45.

[8]

 The method of claim 3,

 Wherein the refractive index of the polymer matrix is 1.45 to 1.70.

[Claim 9]

 The method of claim 3,

 The polymeric matrix or precursor thereof may comprise: 1) the reaction product of a compound comprising at least one isocyanate group with a polyol; Or 2) a (meth) acrylate-based (co) polymer and a silane crosslinking agent in which the silane-based functional group is located in the branch chain.

Claim 10

 9. The method of claim 8,

 Wherein the silane crosslinking agent comprises a linear polyether main chain having a weight average molecular weight of 100 to 2000 and a silane functional group bound to the main chain at the terminal or branch chain.

Claim 11 2019/112358 1 »(: 1 ^ 1 {2018/015467

In Item 13,

 Wherein the photoreactive monomer comprises a polyfunctional (meth) acrylate monomer having a refractive index of 1.5 or more, or a monofunctional (meth) acrylate monomer having a refractive index of 1.5 or more.

 5

 Claim 12

 An optical element including the hologram recording medium of claim 1.

Claim 13

_{10. A} holographic recording method comprising: selectively polymerizing a photoreactive monomer contained in the hologram recording medium of claim 1 by electromagnetic radiation.