Photopolymer composition

Abstract

The present disclosure relates to a photopolymer composition, and more particularly, to a compound having a novel structure, a photopolymer composition including the compound as a dye, a hologram recording medium produced from the photopolymer composition, an optical element including the hologram recording medium, and a holographic recording method using the photopolymer composition.

Claims

1. A photopolymer composition comprising: a polymer matrix or a precursor thereof; a dye including a compound represented by Chemical Formula 1; a photoreactive monomer; and a photoinitiator: ##STR00010## in the Chemical Formula 1, X is silicon (Si), Z.sub.1 and Z.sub.2 are identical to or different from each other, and each is nitrogen (N) or phosphorus (P), R.sub.1 to R.sub.12 are identical to or different from each other, and each is hydrogen, an alkyl group having 1 to 20 carbon atoms; a halogen group; a nitrile group; a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms; a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms; or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, n and m are each 0 or 1, An.sup.? is an anion, Ar.sub.1 is an aromatic divalent functional group having 6 to 30 carbon atoms unsubstituted or substituted with one or more functional groups selected from the group consisting of an alkyl group having 1 to 20 carbon atoms; a halogen group; a nitrile group; an alkoxy group having 1 to 20 carbon atoms; an aryloxy group having 6 to 20 carbon atoms and an aryl group having 6 to 20 carbon atoms, and Y.sub.1 is a functional group represented by Chemical Formula 2, ##STR00011## wherein, in the Chemical Formula 2, Y.sub.2 is an ether group or an ester, and Ar.sub.2 is an aromatic functional group having 6 to 20 carbon atoms substituted with one or more halogen groups.

2. The photopolymer composition according to claim 1, wherein in the Chemical Formula 1, An.sup.? is a halide ion, a cyano ion, an alkoxy ion having 1 to 30 carbon atoms, an alkoxycarbonyl ion having 1 to 30 carbon atoms, a sulfonate ion, an alkyl-sulfonate ion having 1 to 30 carbon atoms, a substituted or unsubstituted aromatic sulfonate ion having 6 to 30 carbon atoms, an alkyl sulfate ion having 1 to 30 carbon atoms, a sulfate ion, or a substituted or unsubstituted aromatic sulfate ion having 6 to 30 carbon atoms.

3. The photopolymer composition according to claim 1, wherein in the Chemical Formula 1, n and m are each 1, Z.sub.1 and Z.sub.2 are each nitrogen (N), R.sub.1 to R.sub.12 are identical to or different from each other, and each is hydrogen, an alkyl group having 1 to 20 carbon atoms; or a halogen group, and Ar.sub.1 is an aromatic divalent functional group having 6 to 20 carbon atoms to which at least one hydrogen, an alkyl group having 1 to 20 carbon atoms or halogen group is bonded.

4. The photopolymer composition according to claim 1, wherein the polymer matrix or a precursor thereof includes a silane crosslinking agent; and 1) a reaction product between a compound containing one or more isocyanate groups and a polyol; or 2) a polymer matrix including a (meth)acrylate-based (co)polymer having a silane-based functional group in a branched chain.

5. The photopolymer composition according to claim 4, wherein 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 at a terminal end or a branched chain of the main chain.

6. The photopolymer composition according to claim 4, wherein the (meth)acrylate-based (co)polymer includes a (meth)acrylate repeating unit and a (meth)acrylate repeating unit having a silane-based functional group in a branched chain, and has a weight average molecular weight of 100,000 to 1,000,000.

7. The photopolymer composition according to claim 1, wherein the photoreactive monomer includes a polyfunctional (meth)acrylate monomer, or a monofunctional (meth)acrylate monomer.

8. The photopolymer composition according to claim 1, comprising 1% to 80% by weight of the polymer matrix or a precursor thereof; 1% to 80% by weight of the photoreactive monomer; 0.0001% to 10% by weight of the dye; and 0.1% to 20% by weight of the photoinitiator.

9. The photopolymer composition according to claim 1, further comprising at least one compound selected from the group of a catalyst, a phosphate-based compound, and a low refractive index fluorine-based compound.

10. The photopolymer composition according to claim 9, wherein the low refractive index fluorine-based compound includes at least one functional group selected from the group of an ether group, an ester group and an amide group; and at least two difluoromethylene groups.

11. The photopolymer composition according to claim 1, wherein the photopolymer composition is for hologram recording.

12. A hologram recording medium comprising a cured product of the photopolymer composition of claim 1, wherein the hologram recording medium comprises one or more stored holograms.

13. An optical element comprising the hologram recording medium of claim 12.

14. The optical element according to claim 13, the optical element being a hologram display device.

15. A holographic recording method comprising selectively polymerizing photoreactive monomers of the photopolymer composition of claim 1 by a coherent laser, wherein a light interference pattern is stored as a hologram by photopolymerization of the photopolymer composition.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) Hereinafter, the present disclosure will be described in more detail by way of the following examples. However, these examples are given for illustrative purposes only and are not intended to limit the scope of the present disclosure thereto.

PREPARATION EXAMPLE

Preparation Example 1: Synthesis of Dye Compound

(1) Preparation of 3-Bromo-N,N-dimethylaniline (Compound 2)

(2) ##STR00006##

(3) 28 ml of 3M sulfuric acid was added to 130 ml of an aqueous solution of tetrahydrofuran containing 37% formaldehyde. The mixture was cooled to 0? C. and stirred further for 10 minutes.

(4) After the stirring, 3-bromoaniline (8 g, 0.0465 mol) was added dropwise at 0? C., and solid NaBH.sub.4 (7 g, 0.1860 mol) was added while maintaining the temperature at 0? C. The resulting mixture was warmed to room temperature and stirred for 1 hour. Then, 180 ml of saturated aqueous sodium hydrogen carbonate solution was added, and the reaction mixture was extracted with 50 ml of dichloromethane three times in total. The obtained organic layer was dried over anhydrous magnesium sulfate, filtered, and then the solvent was removed in vacuo.

(5) Yield: 8.84 g (95%).

(6) 1H NMR (CDCl.sub.3): 7.10-7.06 (1H, t, Ar), 6.84-6.81 (2H, m, Ar), 6.64-6.61 (1H, d, Ar), 2.94 (6H, s, 2CH.sub.3).

(2) Preparation of 3,3-(Dimethylsilanediyl)-bis(N,N-dimethylaniline) (Compound 4)

(7) ##STR00007##

(8) 60 ml of diethyl ether solution in which 3-bromo dimethyl aniline (Product 2; 7 g, 0.0352 mol) was dissolved was cooled to 0? C., and n-BuLi (2.4 M n-hexane solution, 15.4 ml, 0.0369 mol) was added under nitrogen.

(9) The reaction mixture was stirred at 0? C. for 2 hours, and 10 ml of diethyl ether in which dichlorodimethylsilane (2.5 ml, 0.0211 mol) was dissolved was added dropwise to the reaction. The mixture was slowly warmed to room temperature and stirred for 24 hours. Then, 50 ml of water was added and the aqueous layer was extracted with ethyl ether, the obtained organic layer was collected and dried over magnesium sulfate. The solvent was removed from the dried material under vacuum, and the residue was purified by column chromatography (hexane/EA: 9/1).

(10) Yield: 2.7 g (52%).

(11) 1H NMR (CDCl.sub.3): 7.25-7.21 (2H, t, Ar), 6.94-6.90 (4H, m, Ar), 6.77-6.74 (2H, d, Ar), 2.91 (12H, s, 4CH.sub.3), 0.53 (6H, s, 2CH.sub.3).

(3) Preparation of 2,4-Dibromophenyl 4-formylbenzoate (Compound 6)

(12) ##STR00008##

(13) N,N-dicyclohexylcarbodiimide (DCC, 1.9 g, 0.0093 mol) and 4-dimethylaminopyridine (DMAP, 0.08 g, 0.0006 mol) were added to 20 ml of dichlomethane solution in which terephthalic acid (starting material 5; 1 g, 0.0066 mol) was dissolved at room temperature. Then, 2,4-dibromophenol (1.6 g, 0.0066 mol) was added, the reaction mixture was stirred at room temperature for 24 hours and then the precipitate was filtered. The obtained filtrate was concentrated in vacuo and the residue was stirred in 20 ml of ethyl alcohol for 30 minutes, then filtered and dried.

(14) Yield: 2.2 g (88%).

(15) 1H NMR (CDCl.sub.3): 10.16 (1H, s, CHO), 8.41-8.38 (2H, d, Ar), 8.06-8.03 (2H, d, Ar), 7.83 (1H, s, Ar), 7.55-7.51 (1H, d, Ar), 7.21-7.18 (1H, d, Ar).

(4) Preparation of N-(10-(4-((2,4-dibromophenoxy)carbonyl)phenyl)-7-(dimethylamino)-5,5-dimethyldibenzo[b,e]silin-3(5H)-ylidene)-p-methylbenzenesulfonate Salt (Dye of Compound 7, Silarhodamine Dye)

(16) ##STR00009##

(17) Intermediate 4 (0.5 g, 0.0016 mol), Intermediate 6 (0.64 g, 0.0016 mol) and p-toluenesulfonic acid monohydrate (0.3 g, 0.0016 mol) were added in 5 ml ethylene glycol in a pressure tube, sealed and heated at 140? C. for 12 hours. After the heating, the reaction mixture was cooled to room temperature, 5 ml of methanol, 5 ml of dichloromethane and 0.47 g (0.0019 mol) of chloranil were added and stirred at room temperature for 1 hour. Then, 50 ml of water was added and the product was extracted with 20 ml dichloromethane three times in total. The obtained organic layer was then dried over magnesium sulfate, filtered and concentrated in vacuo. The residue was purified by column chromatography (CH.sub.2Cl.sub.2/EA/MeOH: 7/2/1) and recrystallized from tetrahydrofuran.

(18) Yield: 0.2 g (20%).

(19) 1H NMR (CDCl.sub.3): 8.40-8.37 (2H, d, Ar), 7.85-7.81 (3H, m, Ar), 7.57-7.53 (1H, d, Ar), 7.45-7.42 (2H, d, Ar), 7.25-7.21 (2H, m, Ar), 7.10-7.03 (4H, m, Ar), 6.67-6.63 (2H, d, Ar), 3.40 (12H, s, 4CH3), 2.30 (3H, s, CH3), 0.64 (6H, s, 2CH.sub.3).

(20) 2) UV-VIS Spectrum: ?max=657 nm

(21) The synthesized dye was diluted to 0.001 wt % with methyl ethyl ketone (MEK) solvent using a UV-Vis Spectrophotometer, and the absorbance (%) in the wavelength range of 380 nm to 780 nm was measured to determine the maximum absorption wavelength.

Preparation Example 2: Preparation of Non-Reactive Low Refractive Index Material (P-1)

(22) 20.51 g of 2,2-((oxybis(1,1,2,2-tetrafluoroethane-2,1-diyl))bis(oxy))bis(2,2-difluoroethan-1-ol) was placed in a 1000 ml flask, and then dissolved in 500 g of tetrahydrofuran and 4.40 g of sodium hydride (60% dispersion in mineral oil) was carefully added several times while stirring at 0? C. for 20 minutes, 12.50 ml of 2-methoxyethoxymethyl chloride was slowly dropped. When it was confirmed that all of the reactants have been consumed by .sup.1H NMR, the reaction solvent was removed under reduced pressure. After extraction was performed three times with 300 g of dichloromethane, the organic layer was collected, and filtered with magnesium sulfate, applied to reduced pressure to remove all dichloromethane. Thereby, 29 g of a liquid product having a purity of 95% or more was obtained at a yield of 98%.

Preparation Example 3: Preparation of (meth)acrylate-based (Co)Polymer in which Silane Functional-Based Group is Located in a Branched Chain

(23) 69.3 g of butyl acrylate and 20.7 g of KBM-503 (3-methacryloxypropyltrimethoxysilane) were placed in a 2 L jacket reactor, and diluted with 700 g of ethyl acetate. The reaction temperature was set at about 70? C. and stirring was performed for about one hour. 0.02 g of n-dodecyl mercaptan was further added and stirring was performed for about 30 minutes. Then, 0.06 g of AIBN, which is a polymerization initiator, was added and polymerization was allowed to proceed for 4 hours or more at the reaction temperature and maintained until the content of the residual acrylate became less than 1%, thereby preparing (meth)acrylate-based (co)polymer (weight average molecular weight: about 900,000, Si(OR).sub.3 equivalent weight: 1019 g/equivalent) in which a silane-based functional group is located in a branched chain.

Preparation Example 4: Preparation of Silane Crosslinking Agent

(24) 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. Stirring was performed at room temperature until being confirmed by TLC that all the reaction material had been consumed, the reaction solvent was all removed under reduced pressure.

(25) 28 g of a liquid product having a purity of 95% or more was separated at a yield of 91% through column chromatography under a developing solution of dichloromethane:methyl alcohol=methyl alcohol=30:1 to obtain a silane crosslinking agent.

Examples and Comparative Examples: Preparation of Photopolymer Composition

(26) As shown in Table 1 below, the (meth)acrylate-based (co)polymer of Preparation Example 3 in which the silane-based functional group is located in a branched chain, a photoreactive monomer (high refractive index acrylate, refractive index of 1.600, HR6022 [Miwon Specialty Chemical]), the non-reactive low refractive index material of Preparation Example 2, tributyl phosphate [TBP], molecular weight 266.31, refractive index 1.424, manufactured by Sigma-Aldrich), Ethyl Violet and Eosin dye (manufactured by Sigma Aldrich), Compound 7 of Preparation Example 1 (Red photosensitive dye, ?max=357 nm) and New Methylene Blue N (Aldrich) and Victoria Pure Blue BO (Aldrich), Ethyl Violet and Eosin (dyes, products at Sigma-Aldrich), Ebecryl P-115 (SK entis), Borate V (Spectra Group), Irgacure 250 (Onium salt, BASF) and methyl isobutyl ketone (MIBK) were mixed in a state where light was blocked, and stirred for about 10 minutes with a Paste mixer to obtain a clear coating solution.

(27) The silane crosslinking agent of Preparation Example 4 was added to the coating solution and further stirred for 5 to 10 minutes. Then, DBTDL as a catalyst was added to the coating solution, stirred for about 1 minute, then coated to a thickness of 7 ?m on a TAC substrate having a thickness of 80 ?m using a Meyer bar and dried at 40? C. for 1 hour.

Experimental Example: Holographic Recording

(28) (1) The photopolymer-coated surfaces prepared in each of Examples and Comparative Examples were laminated on a slide glass, and fixed so that a laser first passed through the glass surface at the time of recording.

(29) (2) Measurement of Diffraction Efficiency (?)

(30) A holographic recording was done via interference of two interference lights (reference light and object light), and the transmission-type recording was done so that the two beams were incident on the same side of the sample. The diffraction efficiencies are changed according to the incident angle of the two beams, and become non-slanted when the incident angles of the two beams are the same. In the non-slanted recording, the diffraction grating is generated vertically to the film because the incident angles of the two beams are the same on the normal basis.

(31) The recording (2?=45?) was done in a transmission-type non-slanted manner using a laser with a wavelength of 532 nm or a laser with a wavelength of 633 nm, and the diffraction efficiency (n) was calculated according to the following Equation 1.

(32) $\begin{array}{cc}?=\frac{P_D}{P_D+P_T}& \left[\mathrm{Equation}1\right]\end{array}$

(33) In the Equation 1, n is a diffraction efficiency, P.sub.D is an output amount (mW/cm.sup.2) of the diffracted beam of a sample after recording, and P.sub.T is an output amount (mW/cm.sup.2) of the transmitted beam of the recorded sample.

(34) (3) Measurement of the Refractive Index Modulation Value(n)

(35) The lossless dielectric grating of the transmission-type hologram can calculate the refractive index modulation value (?n) from the following Equation 2.

(36) $\begin{array}{cc}?\left(\mathrm{DE}\right)={\sin }^2\left(\sqrt{v^2}\right)={\sin }^2\left(\frac{??\mathrm{nd}}{?\cos ?}\right)& \left[\mathrm{Equation}2\right]\end{array}$ in the Equation 2, d is a thickness of the photopolymer layer, (?n) is a refractive index modulation value, (?)DE) is a diffraction efficiency, and ? is a recording wavelength.

(37) TABLE-US-00001 TABLE 1 Measurement Results of Experimental Examples of Photopolymer Compositions of Examples (unit: g) and Holographic Recording Medium Prepared Therefrom Comparative Comparative Category Example 1 Example 2 Example 3 Example 4 Example 1 Example 2 (Meth)acrylate- Preparation 21.5 21.5 21.5 21.5 21.5 21.5 based Example 3 copolymer Linear silane Preparation 6.1 6.1 6.1 6.1 6.1 6.1 crosslinking Example 4 agent Photoreactive HR6022 40.2 40.2 40.2 40.2 40.2 40.2 monomer Dye Preparation 0.22 0.22 0.1 Example 1 New Methylene 0.3 0.3 Blue N (Aldrich) Victoria Pure 0.3 Blue BO (Aldrich) Initiator Amine (Ebecryl 1.5 P-115) Borate salt 0.18 0.18 0.27 0.3 0.3 (Borate V) Onium salt 0.04 0.1 0.1 0.2 (Irgacure 250) Non-reactive Preparation 30 30 30 30 30 30 low refractive Example 2 index material Catalyst DBTDL(dibutyltin 0.02 0.02 0.02 0.02 0.02 0.02 dilaurate) Additive Tego Rad 2500 0.22 0.22 0.22 0.22 0.22 0.22 Solvent MIBK 295 295 295 296 300 300 Coating thickness (unit: ?m) 6.5 6.5 6.5 6.5 6.5 6.5 Recording time (sec) 10 10 10 30 30 45 ?n 0.028 0.027 0.03 0.01 0.005 0.012

(38) As shown in Table 1 above, it was confirmed that the hologram recording medium of Examples 1 to 3 can realize a refractive index modulation value (?n) of 0.027 or more at a thickness of 6.5 ?m. In contrast, it was confirmed that the hologram recording medium of Comparative Examples 1 to 3 has a relatively low diffraction efficiency as compared with Examples.

(39) That is, as the result of the evaluation after hologram recording (632 nm Laser) for Examples 1 to 3, it was confirmed that when the compound 7 dye of Preparation Example 1 (Silarhodamine Dye) was used, a relatively high level of refractive index modulation value (?n) was realized, and it had a relatively fast reaction rate and could shorten the recording time, as compared with the dye used in the Comparative Examples.