PHOTOPOLYMER COMPOSITION, HOLOGRAM RECORDING MEDIUM, PREPARATION METHOD THEREOF AND OPTICAL ELEMENT COMPRISING THE SAME

Abstract

The present invention relates to a photopolymer composition, a hologram recording medium, a preparation method thereof, and an optical element comprising the same. The photopolymer composition includes an electron donor whose reaction energy with a photosensitizing dye excited into a triplet state is-25 to 0 KJ/mol, thereby being able to provide a hologram recording medium that not only is excellent in optical recording characteristics such as diffraction efficiency which are the basic physical properties of hologram recording media, but also exhibits excellent high-temperature stability over time before recording optical information, so that it can exhibit the originally intended optical recording characteristics even when stored at room temperature to high temperature for a long period of time, and can reproduce clear images without problems such as halo.

Claims

1. A photopolymer composition comprising: a polymer matrix formed by crosslinking a siloxane-based polymer containing a silane functional group and a (meth)acrylic-based polyol, or a precursor thereof; a photoreactive monomer; and a photoinitiator system containing a photosensitizing dye and a coinitiator, wherein the coinitiator includes an electron donor whose reaction energy with a photosensitizing dye excited into a triplet state is 25 to 0 KJ/mol.

2. The photopolymer composition according to claim 1, wherein the siloxane-based polymer comprises a repeating unit represented by the following Chemical Formula 1 and a terminal end group represented by the following Chemical Formula 2: ##STR00015## wherein, in the Chemical Formula 1, a plurality of R.sup.1 and R.sup.2 are the same or different from each other, and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 10,000, ##STR00016## wherein, in the Chemical Formula 2, a plurality of R.sup.11 to R.sup.13 are the same or different from each other, and are each independently hydrogen, halogen, or an alkyl group having 1 to 10 carbon atoms, and at least one of R.sup.1, R.sup.2 and R.sup.11 to R.sup.13 of at least one repeating unit selected among the repeating units represented by Chemical Formula 1 and any one terminal end group selected among the terminal end groups represented by Chemical Formula 2 is hydrogen.

3. The photopolymer composition according to claim 1, wherein the (meth)acrylic-based polyol is a polymer in which a hydroxy group is bonded to a main chain or side chain of the (meth)acrylate-based polymer.

4. The photopolymer composition according to claim 1, wherein a molar ratio of the silane functional group of the siloxane-based polymer to a hydroxy group of the (meth)acrylic-based polyol is 1.5 to 4.

5. The photopolymer composition according to claim 1, wherein the photoreactive monomer comprises at least one monofunctional monomer selected from the group consisting of benzyl (meth)acrylate, benzyl 2-phenylacrylate, phenoxybenzyl (meth)acrylate, phenol (ethylene oxide) (meth)acrylate, phenol (ethylene oxide).sub.2 (meth)acrylate, O-phenylphenol (ethylene oxide) (meth)acrylate, phenylthioethyl (meth)acrylate and biphenylmethyl (meth)acrylate; at least one polyfunctional monomer selected from the group consisting of bisphenol A (ethylene oxide).sub.210 di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisfluorene di(meth)acrylate, modified bisphenol fluorene di(meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, phenol novolac epoxy (meth)acrylate and cresol novolac epoxy (meth)acrylate; or a mixture of two or more thereof.

6. The photopolymer composition according to claim 1, wherein the photoreactive monomer is contained in an amount of 50 to 300 parts by weight based on 100 parts by weight of the polymer matrix.

7. The photopolymer composition according to claim 1, further comprising a fluorinated compound.

8. The photopolymer composition according to claim 7, wherein the composition comprises 17 to 38% by weight of the polymer matrix, 36 to 58% by weight of the photoreactive monomer, and 17 to 38% by weight of the fluorinated compound, based on a total weight of the polymer matrix, the photoreactive monomer, and the fluorinated compound.

9. The photopolymer composition according to claim 1, wherein the photosensitizing dye comprises a silicon rhodamine compound represented by the following Chemical Formula 4: ##STR00017## wherein, in the Chemical Formula 4, R.sup.21 to R.sup.29 are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, or a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, d and e are each independently an integer of 0 to 3, f is an integer of 0 to 5, and An.sup. is an anion.

10. The photopolymer composition according to claim 1, wherein the electron donor comprises a borate anion represented by the following Chemical Formula 5: ##STR00018## wherein, in the Chemical Formula 5, X.sup.1 to X.sup.4 are each independently an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkylaryl group having 7 to 30 carbon atoms, or an allyl group, each of which is substituted or unsubstituted, with the proviso that at least one of X.sup.1 to X.sup.4 is not an aryl group.

11. The photopolymer composition according to claim 1, wherein the electron donor comprises at least one borate anion selected from the group consisting of borate anions represented by the following Chemical Formulas 5-1 and 5-2: ##STR00019## wherein, in the Chemical Formula 5-1, each R.sup.102 is independently methyl or chlorine, each R.sup.103 is independently hydrogen, methyl or chlorine, with the proviso that it is chlorine if the adjacent R.sup.102 is methyl, and X.sup.4 is a straight chain alkyl group having 1 to 12 carbon atoms, ##STR00020## wherein, in the Chemical Formula 5-2, each R.sup.106 is independently hydrogen, methyl or halogen, and X.sup.4 is a straight chain alkyl group having 1 to 12 carbon atoms.

12. The photopolymer composition according to claim 1, wherein the electron donor comprises at least one selected from the group consisting of a cation represented by the following Chemical Formula 5-3 and a cation represented by the following Chemical Formula 5-4: ##STR00021## wherein, in the Chemical Formula 5-3, two of Y.sup.1 to Y.sup.4 are optionally er may not be-connected with each other to form an aliphatic ring having 4 to 10 carbon atoms, and Y.sup.1 to Y.sup.4, which do not form an aliphatic ring, are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms connected through an ester bond, with the proviso that a case where Y.sup.1 to Y.sup.4 are all methyl groups, or at least two of Y.sup.1 to Y.sup.4 are alkyl groups having 16 or more carbon atoms, is excluded, ##STR00022## wherein, in the Chemical Formula 5-4, R.sup.107, R.sup.109 and R.sup.110 are each independently hydrogen, an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms connected through an ester bond, and R.sup.108 and R.sup.111 are each independently an alkyl group having 1 to 40 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 6 to 40 carbon atoms, or an alkyl group having 2 to 40 carbon atoms connected through an ester bond.

13. The photopolymer composition according to claim 1, wherein the coinitiator comprises an electron acceptor.

14. The photopolymer composition according to claim 13, wherein the electron acceptor comprises an onium salt, a triazine compound or a mixture thereof.

15. The photopolymer composition according to claim 13, wherein the electron acceptor is contained in an amount of 0.025 to 2 parts by weight based on 100 parts by weight of the polymer matrix.

16. A hologram recording medium comprising a photopolymer layer formed from the photopolymer composition according to claim 1.

17. The hologram recording medium according to claim 16, wherein the photopolymer layer further comprises a fluorinated compound, wherein an element ratio of carbon is 50 to 70 atomic %, an element ratio of nitrogen is 0.01 to 2 atomic %, an element ratio of oxygen is 15 to 30 atomic %, an element ratio of fluorine is 3 to 12 atomic %, and an element ration of silicon is 3 to 15 atomic %, based on a total amount of carbon, nitrogen, oxygen, fluorine and silicon atoms on a surface thereof as confirmed by photoelectron spectroscopy.

18. The hologram recording medium according to claim 16, wherein when recording a notch filter hologram, a diffraction efficiency is at least 80%.

19. A method for preparing a hologram recording medium, comprising the steps of: applying the photopolymer composition according to claim 1 to form a photopolymer layer; and irradiating a coherent laser onto a predetermined region of the photopolymer layer and selectively polymerizing a photoreactive monomer contained in the photopolymer layer to record optical information.

20. An optical element comprising a hologram recording medium comprising a photopolymer layer formed from the photopolymer composition according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0187] FIG. 1 schematically shows the recording equipment setup for hologram recording. Specifically, FIG. 1 schematically shows the process in which a laser of a predetermined wavelength is radiated from the light source 10, and irradiated onto the PP (hologram recording medium) 80 located on one surface of a mirror 70 via mirrors 20 and 20, an iris 30, a spatial filter 40, an iris 30, a collimation lens 50, and PBS (Polarized Beam Splitter) 60.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0188] Hereinafter, the action and effect of the invention will be described in more detail with reference to specific examples of the invention. However, these examples are presented for illustrative purposes only, and the scope of the invention is not limited thereby in any way.

[0189] In the following Preparation Examples, Examples, Comparative Examples, and the like, the content of raw materials, and the like means the content based on solid content, unless otherwise specified.

Preparation Example 1: Preparation of (Meth)Acrylic-Based Polyol 5

[0190] 132 g of butyl acrylate, 420 g of ethyl acrylate, and 48 g of hydroxybutyl acrylate were added to a 2 L jacketed reactor, and diluted with 1200 g of ethyl acetate. The reaction temperature was set to 6070 C., and the mixture was stirred for about 30 minutes to 1 hour. 0.42 g of n-dodecyl mercaptan(n-DDM) was further added, and stirring was further performed for about 30 minutes. Then, 0.24 g of AIBN as a polymerization initiator was added, polymerization was performed at the reaction temperature for 4 hours or more, and kept until the residual acrylate content became less than 1%. Thereby, a (meth)acrylate-based copolymer (weight average molecular weight of about 300,000, OH equivalent of about 1802 g/equivalent) in which the hydroxy group was located in the branched chain was prepared.

Preparation Example 2: Preparation of Fluorinated Compound

[0191] 20.51 g of 2,2-{oxybis[(1,1,2,2-tetrafluoroethane-2,1-diyl)oxy]}bis(2,2-difluoroethan-1-ol) was added to a 1000 mL flask, and dissolved in 500 g of tetrahydrofuran, to which 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 added dropwise. When it was confirmed by 1H NMR that all the reactants were consumed, work-up using dichloromethane gave 29 g of a liquid product with a purity of 95% or more in a yield of 98%. The weight average molecular weight of the prepared fluorinated compound was 586, and the refractive index measured with an Abbe refractometer was 1.361.

Example 1: Preparation of Photopolymer Composition and Hologram Recording Medium

(1) Preparation of Photopolymer Composition

[0192] Trimethylsilyl terminated poly (methylhydrosiloxane) (Sigma-Aldrich, number average molecular weight: about 390, SiH equivalent: about 103 g/equivalent) as a siloxane-based polymer and (meth)acrylic-based polyol prepared in Preparation Example 1 were first mixed. The content of the (meth)acrylic-based polyol was 22.4 g, and the siloxane-based polymer was added so that the SiH/OH molar ratio was 2. In Example 1, 2.6 g of siloxane-based polymer was added.

[0193] Then, 52 g of HR 6042 (Miwon Specialty Chemical, refractive index of 1.60) as a photoreactive monomer, 0.2 g of a compound represented by the following Chemical Formula a as a photosensitizing dye, 0.8 g of hexadecyl dimethyl benzyl ammonium tri(m-chloro-p-methylphenyl) butyl borate, and 0.05 g of 2-(4-methoxyphenyl)-4,6-bis (trichloromethyl)-1,3,5-triazine (TCI) as a coinitiator, 0.9 g of Irgacure 369 as a photoinitiator, 23 g of a fluorinated compound prepared in Preparation Example 2 as a plasticizer, and 190 g of methyl isobutyl ketone (MIBK) as a solvent were added, and the mixture was stirred with a paste mixer for about 30 minutes while blocking light. After that, 0.014 g of Karstedt (Pt-based) catalyst was added for matrix crosslinking to prepare a photopolymer composition.

##STR00013##

(2) Preparation of Hologram Recording Media

[0194] The photopolymer composition was coated to a predetermined thickness on a 60 m thick TAC substrate using a Mayer bar, and dried at 80 C. for 10 minutes. The thickness of the photopolymer layer after drying was about 15 m.

Examples 2 to 10 and Comparative Examples 1 to 4: Preparation of Photopolymer Composition and Hologram Recording Medium

[0195] A photopolymer composition and a hologram recording medium were prepared in the same manner as in Example 1, except that the coinitiator was changed as shown in Table 1 below.

TABLE-US-00001 TABLE 1 Electron donor Electron acceptor Example 1 Hexadecyl dimethyl benzyl ammonium 2-(4-methoxyphenyl)-4,6- tri(m-chloro-p-methylphenyl)butyl borate bis(trichloromethyl)-1,3,5- triazine Example 2 Hexadecyl dimethyl benzyl ammonium tri(m-chloro-p-methylphenyl)butyl borate Example 3 Hexadecyl dimethyl benzyl ammonium 2-(4-methoxyphenyl)-4,6- tri(p-chlorophenyl)butyl borate bis(trichloromethyl)-1,3,5- triazine Example 4 Hexadecyl dimethyl benzyl ammonium tri(p-chlorophenyl)butyl borate Example 5 Tetrabutyl ammonium tri(6-chloro-2- 2-(4-methoxyphenyl)-4,6- naphthyl)butyl borate bis(trichloromethyl)-1,3,5- triazine Example 6 Tetrabutyl ammonium tri(6-chloro-2- naphthyl)butyl borate Example 7 Tetrabutyl ammonium tri(m-chloro-p- 2-(4-methoxyphenyl)-4,6- methylphenyl)butyl borate bis(trichloromethyl)-1,3,5- triazine Example 8 Tetrabutyl ammonium tri(m-chloro-p- methylphenyl)butyl borate Example 9 Tetrabutyl ammonium tri(2- naphthyl)butyl borate Example 10 Hexadecyl benzyl pyrrolidinium tri(p- chlorophenyl)butyl borate Comparative WPBG-300 (1,2-dicyclohexyl- 2-(4-methoxyphenyl)-4,6- Example 1 4,4,5,5-tetramethylbiguanidium bis(trichloromethyl)-1,3,5- tri(phenyl)butyl borate) triazine Comparative WPBG-300 Example 2 Comparative Tetrabutyl ammonium tri(p- Example 3 fluorophenyl)butyl borate Comparative Tetrabutyl ammonium tri(o- Example 4 methylphenyl)hexyl borate

Test Example 1: Analysis of Hologram Recording Medium

(1) Element Ratio

[0196] The surface element ratios of a sample before recording and a sample after recording were analyzed by the method described below.

[0197] Specifically, the sample to be analyzed was fixed onto a copper foil with a carbon tape, which was placed on the sample holder and fixed using a clip. Then, data were acquired using an X-ray photoelectron spectrometer (ESCA, model name: K-Alpha+, Thermo Fisher Scientific Inc.) according to the K-Alpha+standard operating method (SOP-0524-Ok), and the element ratio (atomic %) of the sample surface was analyzed using Avantage software (version 5.980).

[0198] The system specifications of the ESCA device used are as follows. [0199] Base chamber pressure: 1.010.sup.9 mbar [0200] X-ray source: monochromatic Al Ka (1486.6 eV) [0201] X-ray spot size: 400 m [0202] Mode: CAE (Constant Analyzer Energy) mode [0203] Charge compensation: Flood gun (FG03: 100 A, 0.5 V)

[0204] Qualitative analysis was performed on the surface of the sample to be analyzed in the as-received state using an initial survey scan under the following conditions. Depending on the qualitative analysis results, quantitative analysis was performed through narrow scan (snap) for each element. The element ratios at three locations were confirmed for each sample, and the peak background smart method was applied for quantitative analysis. The binding energy correction of the core level spectrum was based on C 1s (284.8 eV).

<Survey Scan Conditions>

[0205] Scan section binding energy: 51350 eV [0206] Step size: 1 eV [0207] Per Point dwell time: 20 ms [0208] Periods: 2 [0209] Pass energy: 200 eV

<Narrow Scan Conditions>

[0210] Scan section binding energy: about 20 e V [0211] Step size: 0.16 eV [0212] Per Point dwell time: 1 sec [0213] Periods: 1030 [0214] Pass energy: 150 eV

<Etching Conditions>

[0215] Source: Ar ion [0216] Energy: 6 ke V [0217] Cluster size: 75 [0218] Rater size: 1.61.0 mm.sup.2 [0219] Mode: GCIB

[0220] All the photopolymer compositions prepared in Examples and Comparative Examples contained a polymer matrix, a photoreactive monomer and a fluorinated compound, which accounted for the largest proportion of their solid contents, in an amount of 25 g, 52 g, and 23 g, respectively, so that the weight ratio of the polymer matrix:photoreactive monomer:fluorinated compound was all 25:52:23.

[0221] As a result, it was shown that the element ratios of all the samples prepared in Examples and Comparative Examples were 62.1 atomic % for carbon, 0.9 atomic % for nitrogen, 21.0 atomic % for oxygen, 6.2 atomic % for fluorine, and 9.8 atomic % for silicon.

[0222] In addition, as a result of measuring the element ratios on the surface of the sample before recording and the sample after recording, the element ratios on the surface of the sample before and after recording were measured to be the same.

(2) Calculation of Reaction Energy

[0223] In order to calculate the reaction energy E2 in Reaction Scheme 1 below, the lowest excited singlet energy (S1) of the borate anion (BX.sup.1X.sup.2X.sup.3X.sup.4) as an electron donor and the lowest excited triplet energy (T1) of the photosensitizing dye (Dye) were determined using Gaussian 16, which is a quantum chemical calculation program manufactured by Gaussian. S1 and T1 were calculated using density functional theory (DFT) for the optimized structure using B3LYP as the functional and 6-31G* as the basis function.

[0224] Since the photosensitizing dye undergoes an electron reduction reaction, T1 is written as a negative value, and since the electron donor undergoes an electron oxidation reaction, S1 is written as a positive value, and the total reaction energy E2 is calculated by adding these.

##STR00014##

TABLE-US-00002 TABLE 2 T1 of S1 of Reaction photosensitizing electron energy dye Types of electron donors donor (E2) Example 1 465.4 kJ/mol Hexadecyl dimethyl benzyl +454.9 kJ/mol 10.5 kJ/mol ammonium tri(m-chloro-p- methylphenyl)butyl borate Example 2 Hexadecyl dimethyl benzyl +454.9 kJ/mol 10.5 kJ/mol ammonium tri(m-chloro-p- methylphenyl)butyl borate Example 3 Hexadecyl dimethyl benzyl +456.9 kJ/mol 8.5 kJ/mol ammonium tri(p- chlorophenyl)butyl borate Example 4 Hexadecyl dimethyl benzyl +456.9 kJ/mol 8.5 kJ/mol ammonium tri(p- chlorophenyl)butyl borate Example 5 Tetrabutyl ammonium tri(6- +456.9 kJ/mol 8.5 kJ/mol chloro-2-naphthyl)butyl borate Example 6 Tetrabutyl ammonium tri(6- +456.9 kJ/mol 8.5 kJ/mol chloro-2-naphthyl)butyl borate Example 7 Tetrabutyl ammonium tri(m- +454.9 kJ/mol 10.5 kJ/mol chloro-p-methylphenyl)butyl borate Example 8 Tetrabutyl ammonium tri(m- +454.9 kJ/mol 10.5 kJ/mol chloro-p-methylphenyl)butyl borate Example 9 Tetrabutyl ammonium tri(2- +443.8 kJ/mol 21.6 kJ/mol naphthyl)butyl borate Example 10 Hexadecyl benzyl pyrrolidinium +456.9 kJ/mol 8.5 kJ/mol tri(p-chlorophenyl)butyl borate Comparative WPBG-300 +435.3 kJ/mol 30.1 kJ/mol Example 1 Comparative WPBG-300 +435.3 kJ/mol 30.1 kJ/mol Example 2 Comparative Tetrabutyl ammonium tri(p- +438.9 kJ/mol 26.5 kJ/mol Example 3 fluorophenyl)butyl borate Comparative Tetrabutyl ammonium tri(o- +399.1 kJ/mol 66.3 kJ/mol Example 4 methylphenyl)hexyl borate

Test Example 2: Evaluation of Performance of Hologram Recording Medium

(1) Thermal Stability (T)

[0225] Thermal stability was evaluated on the basis of the degree of the lowest transmittance change (T) before and after exposure to high temperatures. Specifically, after a diffraction grating was recorded on a sample before recording that was not exposed to high temperatures and a sample before recording that was exposed to high temperatures, the thermal stability was evaluated on the basis of the degree of the lowest transmittance change, and the degree of the lowest transmittance change was determined using the following Equation 1.

[00002]$\begin{array}{cc}T\left(\%\right)=\left\{\left(.Math.T_1-T_0.Math.\right)/T_0\right\}100& \left[\mathrm{Equation}1\right]\end{array}$ [0226] wherein, in Equation 1, T.sub.0 is the lowest transmittance which was measured in the wavelength range of 300 to 1,200 nm using a UV-Vis spectrometer for a notch filter hologram recording sample after the hologram recording medium before recording is stored in a dark room under a constant temperature (20 to 25 C.) and a constant humidity (40 to 50% relative humidity), and T1 is the lowest transmittance which was measured in the same manner as above for a notch filter hologram recording sample after the sample before recording is stored in a dark room at a temperature of 60 C. and a relative humidity of 40 to 50% for 100 hours.

[0227] The notch filter hologram was recorded using the same setup as shown in FIG. 1. Specifically, when the prepared photopolymer layer was laminated on a mirror and then irradiated with a laser, a notch filter hologram with periodic refractive index modulation in the thickness direction could be recorded through interference between incident light (L) and light reflected from the mirror (L). In this example, the notch filter hologram was recorded with an incident angle of 0 (degree). Notch filter and Bragg reflector are optical devices that reflect only light of a specific wavelength, and have a structure in which two layers with different refractive indices are stacked periodically and repeatedly at a constant thickness.

(2) Diffraction Efficiency (DE)

[0228] Diffraction efficiency () was determined through the following Equation 2 for the sample in which the notch filter hologram was recorded in the same manner as mentioned above.

[00003]$\begin{array}{cc}\left(\%\right)=\left\{P_D/\left(P_D+P_T\right)\right\}100& \left[\mathrm{Equation}2\right]\end{array}$ [0229] wherein, in Equation 2, is the diffraction efficiency, PD is the output amount (mW/cm.sup.2) of the diffracted beam of the sample after recording, and P.sub.T is the output amount (mW/cm.sup.2) of the transmitted beam of the sample after recording.

(3) Whether or not Halo Generates

[0230] It was confirmed whether a halo was observed on the hologram recording medium. Specifically, the sample in which the notch filter hologram was recorded in the above-described manner was irradiated with the incident light (L) that was irradiated during hologram recording, and holographic optical information was reproduced. Then, the reproduced holographic optical information was observed with the naked eye to determine whether a halo, which is a cloudy-looking area, was observed around the reproduced holographic optical information.

[0231] It is marked as OK if no halo is observed on the holographic optical information recording medium, and as NG if a halo was observed.

TABLE-US-00003 TABLE 3 Reaction Thermal Diffraction Whether or energy stability efficiency not halo (E2) (T, %) (DE, %) generates Example 1 10.5 kJ/mol 3.2 97.0 OK Example 2 10.5 kJ/mol 5.8 89.2 OK Example 3 8.5 kJ/mol 0.8 98.0 OK Example 4 8.5 kJ/mol 1.2 92.7 OK Example 5 8.5 kJ/mol 2.1 91.2 OK Example 6 8.5 kJ/mol 4.2 87.8 OK Example 7 10.5 kJ/mol 7.8 90.2 OK Example 8 10.5 kJ/mol 11.2 88.5 OK Example 9 21.6 kJ/mol 15.3 87.9 OK Example 10 8.5 kJ/mol 2.2 91.5 OK Comparative 30.1 kJ/mol 78 92.1 NG Example 1 Comparative 30.1 kJ/mol 92.8 89.2 NG Example 2 Comparative 26.5 kJ/mol 94 93.2 NG Example 3 Comparative 66.3 kJ/mol 100 96.4 NG Example 4

[0232] Referring to Table 3, it is confirmed that the photopolymer composition according to one embodiment of the invention includes an electron donor whose reaction energy with a photosensitizing dye excited into a triplet state is-25 to 0 KJ/mol, thereby being able to provide a hologram recording medium that not only is excellent in optical recording characteristics such as diffraction efficiency, but also exhibits excellent stability over time at high temperatures before recording. In addition, it is confirmed that the hologram recording media prepared in Examples can reproduce clear images without problems such as halo.