JP2011043620A - Hologram recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram optical recording medium having excellent long-term storability of recorded data and no distortion, and to provide a medium having less volume shrinkage during recording. <P>SOLUTION: The hologram recording medium contains: (a) a three-dimensional crosslinked polymer matrix; (b) at least one of a spiro-ortho-ester, spiro-ortho-carbonato, cyclic carbonato and bicycle-ortho-ester; (c) an aluminum complex having β-diketone as a ligand in which the α-site carbon of the carbonyl group has an alkyl group; and (d) an organic silicon compound having a silanol hydroxyl group. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a hologram recording medium.

  Holographic memories that record information as holograms are capable of high-capacity recording and are attracting attention as next-generation recording media. As a photosensitive composition for hologram recording, for example, a composition mainly composed of a radical polymerizable monomer, a thermoplastic binder resin, a photo radical polymerization initiator, and a sensitizing dye is known. Information is recorded by making a photosensitive composition for hologram recording into a film and performing interference exposure.

  The polymerization reaction of the radical polymerizable monomer proceeds in the portion where the light is strongly irradiated, the radical polymerizable monomer diffuses from the portion where the light is weakly irradiated toward the portion where the light is strongly irradiated, and the concentration gradient is increased. appear. That is, the difference in the refractive index can be made by the difference in density of the radical polymerization monomer depending on the intensity of the interference light. However, with the polymerization of the polymerizable monomer, the recording layer may locally shrink, and in this case, it becomes difficult to accurately reproduce the recorded data.

  In order to suppress the influence of polymerization shrinkage due to recording, a medium in which a monomer that expands by polymerization is dispersed in the recording layer (for example, see Patent Documents 1 and 2), a medium to which a photodegradable expansion agent is added, etc. are proposed. (For example, see Patent Document 3).

  Further, the hologram recording medium is used for long-term storage of data, and for this reason, long-term stability of the medium is required. A three-dimensional crosslinked polymer matrix is used as the matrix material that retains the volume, but it is difficult to completely complete the crosslinking reaction, and some unreacted functional groups remain. If the reaction of the unreacted part gradually proceeds during storage, the recording layer may be contracted, which may make it difficult to accurately reproduce the recorded part.

  Further, the three-dimensional crosslinked polymer matrix is a cured product such as an epoxy compound, and shrinks when cured to produce a medium, so that the recording layer may peel off from the substrate or cause optical distortion.

JP 2000-86914 A JP 2004-341016 A JP 2008-268516 A

Toshikazu Takada and Nobuhiro Kihara, “Precision Polymer Design by Ring-Opening Polymerization”, Kobunka Kyoku 47 (11) (pp482-488) Endo Go, Toshikazu Takada, “Synthesis of functional polymers using spiro compounds”, Journal of Petroleum Sciences, Vol. 32, No. 5, (1989), pp237-247. Lisa Dhar, Melinda G. Schnoes, Theresa L. Wysocki, Harvey Bair, Mercia Shchilling, Caril Boyd, Applied Physics Letters, Volume 73, Number 10, pp1337-1339 (1998)

  The present invention provides a hologram optical recording medium that is excellent in long-term storage stability of recorded data and has no distortion. Further, the present invention provides a medium with a small volume shrinkage during recording.

The hologram recording medium of the present invention has a recording layer.
(a) Three-dimensional cross-linked polymer matrix
(b) At least one of spiro ortho ester, spiro ortho carbonate, cyclic carbonate, and bicyclo ortho ester
(c) an aluminum complex having a β-diketone having an alkyl group at the α-position carbon of the carbonyl group as a ligand
(d) It contains an organosilicon compound having a silanolic hydroxyl group.

  A hologram recording medium according to another aspect of the present invention includes a three-dimensional crosslinked polymer matrix made of an epoxy resin. Furthermore, it contains a radical polymerizable compound and a photo radical polymerization initiator.

  According to the present invention, there is provided a hologram optical recording medium that is excellent in long-term storage stability of recorded data and is free from distortion and peeling. Further, the present invention provides a medium with a small volume shrinkage during recording.

Specific examples of spiro orthoesters, spiro ortho carbonates, and cyclic carbonates according to the present invention. 1 is a schematic view of a transmission type optical recording / reproducing apparatus according to the present invention. 1 is a schematic sectional view of a transmission hologram recording medium according to the present invention.

  Embodiments of the present invention will be described below.

  The recording layer in the hologram recording medium according to one embodiment of the present invention contains a compound selected from at least one of spiro ortho ester, spiro ortho carbonate, cyclic carbonate, and bicyclo ortho ester. In polymerization reactions of polymerizable monomers such as radical polymerization and cationic polymerization, it is known that volume shrinkage occurs because the distance between molecules is shortened by polymerizing or curing from the monomer state. On the other hand, spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and bicycloorthoesters are high in density because of the large interaction between molecules before polymerization, and there is little change in the distance between molecules even when ring-opening polymerization of these. It is known that the shrinkage is extremely small or expands (for example, Non-Patent Documents 1 and 2).

  The three-dimensional cross-linked polymer matrix included in the recording layer of the present invention includes, for example, a polymer of epoxy and amine compound, a polymer of epoxy and acid anhydride, a polymer of epoxy and thiol compound, and a polymer of urethane and polyol. Examples include coalescence. In the curing reaction, it is difficult to completely react the functional group, and the functional group incorporated inside the molecular chain network may remain unreacted. The hologram recording medium is considered to be mainly used as an archival medium, and it is required that data can be accurately reproduced even after several decades after recording. However, if the unreacted functional group in the matrix gradually reacts over a long period of time, the recording layer shrinks little by little, and accurate data reading becomes difficult.

  If the three-dimensional crosslinked polymer matrix is heated at 120-150 ° C or higher, the unreacted part can be reduced to a negligible level. However, the polymerization initiator for the optical recording and the polymerizable monomer react to cause high performance. The medium cannot be obtained.

  The recording layer of the present invention contains an aluminum complex having a β-diketone having an alkyl group at the α-position carbon of the carbonyl group and an organosilicon compound having a silanolic hydroxyl group. When both are mixed in the same system, an epoxy cationic polymerization initiator is obtained. However, this cationic polymerization initiator is a weak acid compared to onium salts and the like, and the reaction efficiency for cationic polymerization of the above-mentioned spiroorthoesters, spiroorthocarbonates, cyclic carbonates and bicycloorthoesters is not high. However, during storage at a high temperature or for a long time at room temperature, the spiro orthoester or the like gradually undergoes cationic polymerization and expands to compensate for the shrinkage of the three-dimensional crosslinked polymer matrix.

  In addition, the three-dimensional crosslinked polymer matrix is a cured product such as an epoxy compound, and cures and shrinks when a medium is manufactured. Therefore, the recording layer may peel off from the substrate or cause optical distortion. When an aluminum complex having a β-diketone having an alkyl group at the α-position carbon of the carbonyl group and an organosilicon compound having a silanolic hydroxyl group are mixed in the same system, it acts as a cationic polymerization initiator. As described above, the reaction efficiency of cationic polymerization of spiro ortho ester, spiro ortho carbonate, cyclic carbonate, and bicyclo ortho ester is not high, but part of it reacts at the time of media preparation to compensate for shrinkage of 3D polymer matrix. It is possible to prevent the layer from peeling off from the substrate or causing optical distortion. It is more effective to add a strong thermal latent cationic polymerization initiator such as an onium salt.

  As the three-dimensional cross-linked polymer matrix, an epoxy cured product is preferably used. Epoxy compounds include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, di Epoxy octane, resorcinol diglycidyl ether, diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate, and epoxypropoxypropyl terminated polydimethyl Examples thereof include siloxane.

  Examples of the compound (curing agent) for curing the epoxy compound include amines, phenols, organic acid anhydrides, and amides known as epoxy curing agents. Specifically, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, mensendiamine, isophoronediamine, bis (4-amino-3-methyldicyclohexyl) methane, bis (amino Methyl) cyclohexane, N-aminoethylpiperazine, m-xylylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, trimethylhexamethylenediamine, iminobispropylamine, bis (hexamethylene) triamine, 1,3 , 6-Trisaminomethylhexane, dimethylaminopropylamine, aminoethylethanolamine, tri (methylamino) hexane, m-phenylenediamine, p-phenylenediamine, diaminodi Phenylmethane, diaminodiphenylsulfone, 3,3′-diethyl-4,4′-diaminodiphenylmethane, maleic anhydride, succinic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, Methyl hexahydrophthalic acid, methylcyclohexene tetracarboxylic anhydride, phthalic anhydride, trimellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bis (anhydrotrimellitate), phenol novolac resin, cresol novolac resin, polyvinylphenol Terpene phenol resin, and polyamide resin.

  Aliphatic primary amines are preferably used because they cure quickly and can be cured at room temperature. Among these, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and iminobispropylamine are particularly suitable. These amines are preferably used in such a compounding amount that the NH— of the amine is from 0.6 times the equivalent to 2 times the equivalent to the oxirane of the epoxy compound. When the amine is blended in less than 0.6 times or more than twice the equivalent, sensitivity and diffraction efficiency may be lowered.

  Furthermore, you may add a curing catalyst as needed. As the curing catalyst, a basic catalyst known as an epoxy curing catalyst can be used. Examples thereof include tertiary amines, organic phosphine compounds, imidazole compounds and derivatives thereof. Specifically, triethanolamine, piperidine, N, N′-dimethylpiperazine, 1,4-diazadicyclo (2,2,2) octane (triethylenediamine), pyridine, picoline, dimethylcyclohexylamine, dimethylhexylamine, benzyldimethyl Amine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, DBU (1,8-diazabicyclo (5,4,0undecene-7), or a phenol salt thereof, trimethylphosphine , Triethylphosphine, tributylphosphine, triphenylphosphine, tri (p-methylphenyl) phosphine, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2 Phenyl-4-methylimidazole, 2-heptaimidazole, etc. Using a latent catalyst such as boron trifluoride amine complex, dicyandiamide, organic acid hydrazide, diaminomaleonitrile and its derivatives, melamine and its derivatives, and amine imide. In addition, a mixture of an aluminum complex having a β-diketone having an alkyl group as the carbon at the α-position of the carbonyl group and an organosilicon compound having a silanolic hydroxyl group contained in the recording medium of the present invention. An epoxy compound obtained by cationic polymerization is also suitably used as the three-dimensional crosslinked polymer matrix.

  Examples of the aluminum complex having a β-diketone having an alkyl group as the carbon at the α-position of the carbonyl group include tris (dipivaloylmethanato) aluminum described in JP-A-57-10622, 1,1 , 1-trimethyl-2,4-pentadionatoaluminum, diisopropoxy-dipivaloylmethanatoaluminum, diacetoxy-dipivaloylmethanatoaluminum, tris (benzoyltrimethylacetylacetonato) aluminum, di-o-tolyloxy- Dipivaloylmethanatoaluminum, di (acetylacetonato) pivaloylmethanatoaluminum, tris (butanoylpivaloylmethanato) aluminum, and aluminum trisethylacetoacetate, aluminum ethylacetoacetate / diisopropylate manufactured by Kawaken Fine Chemical Co., Ltd. And aluminum bisethylacetoacetate monoacetylacetonate, aluminum trisacetylacetonate, and the like.

  Examples of organosilicon compounds having silanolic hydroxyl groups include diphenylsilanediol, triphenylsilanol, diphenylmethylsilanol, phenylvinylsilanediol, tri (paramethoxyphenyl) silanol, triacetylsilanol, diphenyl described in JP-A-57-10622. Ethylsilanol, diphenylpropylsilanol, tri (paranitrophenyl) silanol, phenyldivinylsilanol, 2-butenyldiphenylsilanol, 2- (2-pentenyl) phenylsilanol, phenyldipropylsilanol, paramethylpentyldimethylsilanol, triethylsilanol, Trimethylsilanol, tripropylsilanol, tri-n-butylsilanol, triisobutylsilanol, 1,3-dihydroxy-1,3-dimethyl-1,3- Phenyldisiloxane, 1,5-dihydroxy-1,3,5-trimethyl-1,3,5-triphenyltrisiloxane, 1,7-dihydroxy-1,3,5,7-tetramethyl-1,3, 5,7-tetraphenyltetrasiloxane, 1,3-dihydroxytetraphenyldisiloxane, 1,5-dihydroxyhexaphenyltrisiloxane, 1,7-dihydroxyoctaphenyltetrasiloxa, 1,5-dihydroxy-3,3- Dimethyl-1,1,5,5-tetraphenyltrisiloxane, 1,3-dihydroxytetra (dimethylphenyl) disiloxane, 1,5-dihydroxyhexaethyltrisiloxane, 1,3,5-trihydroxy-3-ethyl -1,1,5,5-tetramethyltrisiloxane, 1,5-dihydroxy-1,1,5,5, -tetraphenyl-3,3-di-paratolyltrisiloxane and the like. The organosilicon compound having a silanolic hydroxyl group has at least 1 equivalent of silanolic hydroxyl group per mole of an aluminum complex having a β-diketone having a carbon atom at the α-position of the carbonyl group as the ligand. It is desirable to blend so as to be −5 equivalents. An aluminum complex having a β-diketone having an alkyl group as the carbon at the α-position of the carbonyl group and an organosilicon compound having a silanolic hydroxyl group, the total of these is 1-30 wt% with respect to the entire recording layer material. It is desirable to do. If the amount is less than 1% by weight, a sufficient archival life cannot be obtained, and if it exceeds 30% by weight, the rate of occurrence of errors due to light scattering may increase.

  Examples of the spiroorthoester, spiroorthocarbonate, cyclic carbonate, and bicycloorthoester include those described in Non-Patent Documents 1 and 2 above. Specifically, the compounds shown in (Chemical Formula 1) to (Chemical Formula 17) in FIG. The spiro ortho ester, spiro ortho carbonate, cyclic carbonate, and bicyclo ortho ester are preferably 1-30 wt% based on the entire recording layer material. If the amount is less than 1% by weight, a sufficient archival life cannot be obtained, and if it exceeds 30% by weight, the rate of occurrence of errors due to light scattering may increase.

  In the recording layer of the present invention, a radical polymerizable compound is preferably mixed as a monomer that is polymerized during recording. Examples of the radical polymerizable compound include compounds having an ethylenically unsaturated double bond. Examples thereof include unsaturated carboxylic acids, unsaturated carboxylic acid esters, unsaturated carboxylic acid amides, and vinyl compounds. Specifically, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, bicyclopentenyl acrylate , Phenyl acrylate, isobornyl acrylate, adamantyl acrylate, methacrylic acid, methyl methacrylate, propyl methacrylate, butyl methacrylate, phenyl methacrylate, phenoxyethyl acrylate, chlorophenyl acrylate, adamantyl methacrylate, isobornyl methacrylate, N -Methylacrylamide, N, N-dimethylacrylamide, N, N-methylenebisacrylamide, acryloylmol Phosphorus, vinyl pyridine, styrene, bromostyrene, chlorostyrene, tribromophenyl acrylate, trichlorophenyl acrylate, tribromophenyl methacrylate, trichlorophenyl methacrylate, vinyl benzoate, 3,5-dichlorovinyl benzoate, vinyl naphthalene, vinyl naphthoate, naphthyl Methacrylate, naphthyl acrylate, N-phenylmethacrylamide, N-phenylacrylamide, N-vinylpyrrolidinone, N-vinylcarbazole, 1-vinylimidazole, 1-bromo-2-vinylnaphthalene, bicyclopentenyl acrylate, 1,6-hexanediol Diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol Hexaacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, tripropylene glycol diacrylate, propylene glycol trimethacrylate, diallyl phthalate, and triallyl trimellitate and the like.

  These radically polymerizable compounds are preferably blended in a proportion of 1 to 50% by weight with respect to the entire recording layer. When the amount is less than 1% by weight, the refractive index of the recording area cannot be sufficiently increased. On the other hand, when the amount exceeds 50% by weight, the volume shrinkage increases and the resolution may be lowered. More preferably, the blending amount of the radical polymerizable compound is 2 to 30% by weight with respect to the entire recording layer.

  Examples of the photo radical polymerization initiator include imidazole derivatives, organic azide compounds, titanocenes, organic peroxides, and thioxanthone derivatives. Specifically, benzyl, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, benzoin isobutyl ether, 1-hydroxycyclohexyl phenyl ketone, benzyl methyl ketal, benzyl ethyl ketal, benzyl methoxy ethyl ether, 2,2′-diethyl Acetophenone, 2,2′-dipropylacetophenone, 2-hydroxy-2-methylpropiophenone, p-tert-butyltrichloroacetophenone, thioxanthone, 2-chlorothioxanthone, 3,3′4,4′-tetra (t- Butylperoxycarbonyl) benzophenone, 2,4,6-tris (trichloromethyl) 1,3,5-triazine, 2- (p-methoxyphenyl) -4,6-bis (trichlorome 1) 1,3,5-triazine, 2-[(p-methoxyphenyl) ethylene] -4,6-bis (trichloromethyl) 1,3,5-triazine, Irgacure 149, 184 manufactured by Ciba Specialty Chemicals, 369, 651, 784, 819, 907, 1700, 1800, 1850 and the like, di-t-butyl peroxide, dicumyl peroxide, t-gutylcumyl peroxide, t-butyl peroxyacetate, t -Butyl peroxyphthalate, t-butyl peroxybenzoate, acetyl peroxide, isobutyryl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, methyl ethyl Ketone peroxide, and cyclohexanone peroxide.

  The radical photopolymerization initiator as described above is preferably blended so as to have a ratio of 0.1 to 10% by weight with respect to the entire recording layer. If the amount is less than 0.1% by weight, a sufficient change in refractive index may not be obtained. If the amount exceeds 10% by weight, the light absorption becomes excessively high and the resolution may be lowered. More preferably, the blending amount of the radical photopolymerization initiator is 0.2 to 7.0% by weight.

  If necessary, sensitizing dyes such as cyanine, merocyanine, xanthene, coumarin, and eosin, silane coupling agents, and plasticizers may be added.

  A cationic photopolymerization initiator may be added to promote cationic polymerization of spiro orthoester, spiro ortho carbonate, cyclic carbonate, or bicyclo ortho ester. As the cationic photopolymerization accelerator, known onium salts such as sulfonium salts, ammonium salts and phosphonium salts, triazines and the like can be used as appropriate. By adding these, volume shrinkage due to optical recording can be reduced.

  Specifically, di (para-tertiary butylphenyl) iodonium trifluoromethanesulfonate, di (para-tertiary butylphenyl) iodonium tetrafluoroborate, di (para-tertiary butylphenyl) iodonium tetrafluoroarsenate, di (para-tertiary) (Butylphenyl) iodonium tetrafluoroantimonate, benzoin tosylate, orthonitrobenzyl p-toluenesulfonate, triphenylsulfonium trifluoromethanesulfonate, tri (tertiarybutylphenyl) sulfonium trifluoromethanesulfonate, benzenediazonium p-toluenesulfonate, 2-methyl-4 , 6-Bis (trichloromethyl) -1,3,5-triazine, 2,4,6-tris (trichloro Til) -1,3,5-triazine, 2-phenyl-4,6-bis (trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenyl) Vinyl) -1,3,5-triazine, 2- (4′-methoxy-1′-naphthyl) -4,6-bis (trichloromethyl) -1,3,5-triazine, and the like.

  In the hologram recording layer, it is important that the matrix has an appropriate hardness. If it is too soft, the radical polymerizable monomer diffuses quickly and the polymerization reaction proceeds rapidly, but the recorded signal cannot be retained and an error occurs. Leads to. On the other hand, when the matrix is too hard, the diffusion of the radical polymerizable monomer is slow and recording takes time. Accordingly, the recording layer is prepared such that it exhibits rubber-like elasticity at room temperature (25 ° C.) and has a durometer hardness value of A45 or more and A85 or less. Preferably they are A50 or more and A80 or less, More preferably, they are A55 or more and A75 or less. When it is A45 or more, the volume change of the recording layer due to the movement of the radical polymerizable compound can be suppressed, and when it is A85 or less, the movement of the radical polymerizable compound is not excessively prevented and the recording sensitivity and diffraction efficiency can be maintained. . The durometer hardness shall be measured using JIS K 6253 (rubber hardness test method, consistent with international standard ISO 7619-1: 2004) or a test method corresponding thereto.

  The hologram recording medium according to the embodiment of the present invention can be obtained by coating a recording layer solution containing the above-described components on a substrate to form a recording layer. As the substrate, a glass substrate and a transparent plastic substrate such as polycarbonate or cycloolefin polymer can be used. In order to suppress the deterioration of the substrate due to the recording layer solution or the acid or base generated by light irradiation on the plastic substrate, and to suppress the oxygen in the atmosphere from reaching the recording layer, an inorganic film such as SiO2, SiOC, or SiOCN is 5 nm to 100 nm. It is preferable to coat the surface in contact with the recording layer with a film thickness of a certain degree. If necessary, these inorganic films may be coated on the surface of the substrate in contact with air.

  Casting or spin coating can be employed for applying the recording layer. It is also possible to arrange two glass plates through a resin spacer and pour the recording layer precursor solution into the gap. The film thickness of the recording layer is preferably in the range of 20 μm to 5 mm. If it is less than 20 μm, it is difficult to obtain a sufficient storage capacity, and if it exceeds 5 mm, the transmittance may be lowered and the resolution may be deteriorated. More preferably, the film thickness of the recording layer is in the range of 50 μm to 2 mm.

  In the hologram recording medium according to the embodiment of the present invention, hologram recording / reproduction is performed by causing information light and reference light to interfere with each other inside the recording layer. The hologram (holography) to be recorded may be either a transmission hologram (transmission holography) or a reflection hologram (reflection holography). The interference method between the information beam and the reference beam can be a two-beam interference method or a coaxial interference method. As a light source used for recording, a linearly polarized laser is desirable from the viewpoint of coherence. Specific examples of the laser include a semiconductor laser, a He—Ne laser, an argon laser, and a YAG laser. The light source used for fixing exposure after recording may be any light as long as it can polymerize an unreacted radical polymerizable compound. For example, a xenon lamp, a mercury lamp, a high-pressure mercury lamp Mercury xenon lamp, gallium nitride based light emitting diode, gallium nitride based semiconductor laser, excimer laser, Nd: YAG laser third harmonic (355 nm), Nd: YAG laser fourth harmonic (266 nm), ultraviolet light emitting LED, etc. Is raised.

<Media Evaluation Method>
Below, the medium evaluation method of this embodiment is demonstrated.

<Optical recording / reproducing apparatus and recording / reproducing method>
FIG. 2 is a schematic diagram of a hologram type optical information recording apparatus using a two-beam interference method as an example of the hologram type optical information recording apparatus according to the present embodiment. FIG. 3 shows a schematic view in the vicinity of the hologram type optical recording medium.

  Hereinafter, methods for recording and reproducing holograms and evaluating the performance of hologram type optical recording media will be described.

  A GaN-based semiconductor laser (wavelength 405 nm) having an external resonator is used as the light source device 1, the beam expander 2 expands the light emitted from the light source device 1 to a beam diameter suitable for hologram recording, and the optical element 3 for optical rotation is a beam. The light expanded by the expander is rotated to generate light including an S-polarized component and a P-polarized component. For the optical rotation optical element 3, for example, a half-wave plate, a quarter-wave plate, or the like is used. Of the light transmitted through the optical rotatory optical element 3, the S-polarized component is reflected by the polarizing beam splitter 4 to become information light 10, and the P-polarized component is transmitted through the polarizing beam splitter 4 to become reference light 11. The information light 10 reflected by the polarization beam splitter 4 is reflected by the mirror 7, passes through the electromagnetic shutter 9, and is applied to the recording layer 20 of the transmission hologram type optical recording medium 13 held on the rotary stage 12. The The reference light 11 transmitted through the polarizing beam splitter 4 is rotated 90 degrees by the optical rotatory optical element 5 to become S-polarized light, is reflected by the mirror 6, passes through the electromagnetic shutter 8, and is held on the rotary stage 12. Irradiation is performed so as to intersect the information light 10 in the recording layer 20 of the hologram type optical recording medium 13 to form a transmission type hologram 17.

  Next, a method for reproducing a hologram recorded using the above means will be described. The information light 10 is blocked by closing the electromagnetic shutter 9, and only the reference light 11 is applied to the transmission hologram 17 formed in the recording layer 20 of the hologram optical recording medium 13. A part of the reference light 11 is diffracted by the transmission hologram 17 when passing through the hologram optical recording medium 13, and the diffracted light is detected by the photodetector 14.

Next, a method for evaluating the recording performance of the hologram type optical recording medium will be described. In the present invention, M / # (M number) representing a recording dynamic range is used as an index of hologram recording performance. M / # is expressed by the following equation when the diffraction efficiency from the i-th hologram is ηi when multiplex recording / reproducing of n-page hologram is performed until recording in the same area in the recording layer of the hologram type optical recording medium is impossible. It is expressed as

A hologram type optical recording medium having a larger M / # value has a larger recording dynamic range and better multiplex recording performance. In this embodiment, the diffraction efficiency η is the light intensity detected by the light detector 15 when the hologram type optical recording medium 13 is irradiated with only the reference light 11, and the light intensity detected by the light detector 14 is Id. Then, using the internal diffraction efficiency represented by η = Id / (It + Id), rotating the hologram type optical recording medium 13 using the rotary stage 12 performs angle multiplex recording / reproduction, and measures M / #. did. The information light 10 and the reference light 11 irradiated onto the recording medium 13 had a beam diameter of 4 mm, a light intensity of 7 mW / cm ^2, and 59-angle multiplex recording was performed at 1 ° intervals. After recording, the ultraviolet light source device 16 was irradiated with light for 30 minutes to stabilize the hologram. Hereinafter, the present invention will be described in more detail with reference to specific examples. In this embodiment, a series of operations were performed in a room where light shorter than a wavelength of 600 nm was shielded so that the recording layer was not exposed. The volume shrinkage of the recording part was measured with reference to Non-Patent Document 3.

Example 1
Aluminum as an aluminum complex having 5.0 g of 1,6-hexanediol diglycidyl ether (epoxy equivalent 151, manufactured by Nagase ChemteX Corp.) and β-diketone having an alkyl group at the α-position of the carbonyl group as a ligand Solution A was prepared by mixing and stirring 0.4 g of tris (ethylacetylacetate) in a dark room.

  Further, 5.0 g of 1,6-hexanediol diglycidyl ether (epoxy equivalent 151, manufactured by Nagase ChemteX Corporation) and 0.6 g of triphenylsilanol as an organosilicon compound having a silanolic hydroxyl group were mixed and stirred. Solution B was obtained. After mixing the solution A and the solution B, 5 g of this mixed solution was taken, 0.25 g of spiroorthocarbonate (chemical formula 7), 0.25 g of 2-vinylnaphthalene as a radical polymerizable monomer, and photo radical polymerization. 0.023g of Irgacure 784 which is an initiator was added and mixed to prepare a solution. Finally, defoaming was performed to obtain a recording layer precursor solution.

  The solution was poured onto a glass substrate on which a spacer of a Teflon (registered trademark) sheet was placed, and another glass substrate was placed on the glass substrate and fixed. This was heated in an oven at 60 ° C. for 4 hours to prepare a hologram recording medium test piece having a recording layer having a thickness of 200 μm. Further, there was no peeling between the glass substrate and the recording layer.

  When M / # was measured by the above-described medium evaluation method, the value was 7.4, and the volumetric shrinkage was 0.29%. The medium was stored in an oven at 80 ° C. for 2000 hours, and then M / # of the recording portion was measured. The value was 6.8. A recording layer precursor having the same composition ratio was poured into a mold and heated to prepare a test piece for hardness measurement having a thickness of 5 mm. When the hardness was measured with a durometer in accordance with JIS K 6253, the A hardness was 72.

(Comparative Example 1)
A recording layer precursor solution was prepared with the same composition as in Example 1 except that the spiro orthocarbonate (Chemical Formula 7) was not added. A medium was manufactured in the same manner as in Example 1, and M / # was measured. As a result, the value was 7.3 and the volumetric shrinkage was 0.33%. Further, as in Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording part was measured, and the value was 5.4. Also, peeling occurred between the outer peripheral portion of the recording layer and the glass substrate.

(Example 2)
The same composition as in Example 1 except that 0.05 g of the photocationic polymerization initiator 4-methylphenyl [4- (1-methylethyl) phenyl] iodonium tetrakis (pentafluorophenyl) borate is added to the composition of Example 1. A recording layer precursor solution was prepared. A medium was manufactured by the same operation as in Example 1, and M / # was measured. As a result, the value was 7.4 and the volume shrinkage was 0.19%. In the same manner as in Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording part was measured and found to be 7.0. Further, there was no peeling between the glass substrate and the recording layer.

(Example 3)
A mixture of 5.0 g of diethylene glycol diglycidyl ether and 0.4 g of aluminum tris (ethylacetylacetate) as an aluminum complex having a β-diketone having an alkyl group at the α-position carbon of the carbonyl group in a dark room, Solution A was prepared by stirring.

  Furthermore, 5.0 g of diethylene glycol diglycidyl ether and 0.6 g of triphenylsilanol as an organosilicon compound having a silanolic hydroxyl group were mixed and stirred to obtain a solution B.

  After mixing the solution A and the solution B, 5 g of the mixed solution after stirring was taken, 0.25 g of the spiro orthoester (Chemical Formula 4), 0.25 g of 2-vinylnaphthalene as a radical polymerizable monomer, and a photo radical. 0.05 g of Irgacure 819 which is a polymerization initiator was added and mixed to prepare a solution. Finally, defoaming was performed to obtain a recording layer precursor solution. A medium was produced by the same operation as in Example 1, and M / # was measured. As a result, the value was 7.5 and the volume shrinkage was 0.28%. After storing in an oven at 80 ° C. for 2000 hours in the same manner as in Example 1, the M / # of the recording portion was measured and found to be 6.9. When the hardness of the recording layer was measured by the same operation as in Example 1, the A hardness was 68. Further, there was no peeling between the glass substrate and the recording layer.

(Comparative Example 2)
A recording layer precursor solution was prepared with the same composition as in Example 3 except that the spiro orthoester (Chemical Formula 4) was not added. When a medium was manufactured by the same operation and M / # was measured, the value was 7.3 and the volume shrinkage was 0.36%. Further, as in Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording part was measured and found to be 5.3. Also, peeling occurred between the outer peripheral portion of the recording layer and the glass substrate.

Example 4
The composition of Example 3 is the same as that of Example 3 except that 0.05 g of the photocationic polymerization initiator 4-methylphenyl [4- (1-methylethyl) phenyl] iodonium tetrakis (pentafluorophenyl) borate is added. A recording layer precursor solution was prepared. A medium was prepared by the same operation as in Example 1, and M / # was measured. As a result, the value was 7.4 and the volume shrinkage was 0.17%. In the same manner as in Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording part was measured and found to be 7.0. Further, there was no peeling between the glass substrate and the recording layer.

(Example 5)
Mixing 5.0 g of diethylene glycol diglycidyl ether and 0.4 g of aluminum tris (acetylacetonate) as an aluminum complex having a β-diketone having an alkyl group at the α-position carbon of the carbonyl group in a dark room, Solution A was prepared by stirring.

  Furthermore, 5.0 g of diethylene glycol diglycidyl ether and 0.6 g of triphenylsilanol as an organosilicon compound having a silanolic hydroxyl group were mixed and stirred to obtain a solution B.

  After mixing the solution A and the solution B, 5 g of this mixed solution was taken, 0.25 g of the cyclic carbonate (Chemical Formula 14), 0.25 g of 1-bromo-2-vinylnaphthalene as the radical polymerizable monomer, and light 0.05 g of Irgacure 819 as a radical polymerization initiator was added and mixed to prepare a solution. Finally, defoaming was performed to obtain a recording layer precursor solution. A medium was prepared by the same operation as in Example 1, and M / # was measured. As a result, the value was 8.6 and the volume shrinkage was 0.28%. As in Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording part was measured and found to be 8.1. When the hardness of the recording layer was measured by the same operation as in Example 1, the A hardness was 66. Further, there was no peeling between the glass substrate and the recording layer.

(Comparative Example 3)
A recording layer precursor solution was prepared with the same composition as in Example 5 except that the cyclic carbonate (Chemical Formula 14) was not added. When a medium was prepared by the same operation and M / # was measured, the value was 8.3 and the volume shrinkage was 0.33%. Further, as in Example 1, after storing in an oven at 80 ° C. for 2000 hours, M / # of the recording portion was measured, and the value was 6.8. In addition, peeling occurred between the outer peripheral portion of the recording layer and the glass substrate (Example 6).
A recording layer precursor solution was prepared with the same composition as in Example 5 except that 0.05 g of the photocationic polymerization initiator di (paratertiary butylphenyl) iodonium tetrafluoroantimonate was added to the composition of Example 5. A medium was prepared by the same operation as in Example 1 and M / # was measured. As a result, the value was 8.7 and the volume shrinkage was 0.18%. In the same manner as in Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording portion was measured and found to be 8.0. Further, there was no peeling between the glass substrate and the recording layer.

(Example 7)
Aluminum as an aluminum complex having 5.0 g of 1,6-hexanediol diglycidyl ether (epoxy equivalent 151, manufactured by Nagase ChemteX Corp.) and β-diketone having an alkyl group at the α-position of the carbonyl group as a ligand Solution A was prepared by mixing and stirring 0.4 g of tris (ethylacetylacetate) in a dark room.

  Further, 5.0 g of 1,6-hexanediol diglycidyl ether (epoxy equivalent 151, manufactured by Nagase ChemteX Corporation) and 0.6 g of triphenylsilanol as an organosilicon compound having a silanolic hydroxyl group were mixed and stirred. Solution B was obtained.

  After mixing the solution A and the solution B, 5 g of this mixed solution was taken, 0.25 g of bicycloorthocarbonate (Chemical Formula 2), 0.25 g of 2-vinylnaphthalene as a radical polymerizable monomer, and photo radical polymerization. 0.023g of Irgacure 784 which is an initiator was added and mixed to prepare a solution. Finally, defoaming was performed to obtain a recording layer precursor solution. A medium was prepared by the same operation as in Example 1 and M / # was measured. As a result, the value was 8.3 and the volume shrinkage was 0.27%. Similarly to Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording portion was measured, and the value was 7.8. When the hardness of the recording layer was measured by the same operation as in Example 1, the A hardness was 73. Further, there was no peeling between the glass substrate and the recording layer.

(Comparative Example 4)
A recording layer precursor solution was prepared with the same composition as in Example 7 except that the bicycloorthoester (Chemical Formula 2) was not added. A medium was prepared by the same operation as in Example 1 and M / # was measured. As a result, the value was 8.2 and the volume shrinkage was 0.35%. Further, as in Example 1, after storing in an oven at 80 ° C. for 2000 hours, the M / # of the recording part was measured and found to be 6.3. In addition, peeling occurred between the outer peripheral portion of the recording layer and the glass substrate (Example 8).
A recording layer precursor solution was prepared with the same composition as in Example 7 except that 0.05 g of the photocationic polymerization initiator di (paratertiary butylphenyl) iodonium tetrafluoroantimonate was added to the composition of Example 5. A medium was prepared by the same operation as in Example 1, and M / # was measured. As a result, the value was 8.2 and the volume shrinkage was 0.20%. After storing in an oven at 80 ° C. for 2000 hours in the same manner as in Example 1, the M / # of the recording part was measured and found to be 7.7. Further, there was no peeling between the glass substrate and the recording layer.

DESCRIPTION OF SYMBOLS 1 Light source device 2 Beam expander 3 Optical element for optical rotation 4 Polarizing beam splitter 5 Optical element for optical rotation 6 Mirror 7 Mirror 8 Electromagnetic shutter 9 Electromagnetic shutter 10 Information light 11 Reference light 12 Rotation stage 13 Transmission type hologram optical recording medium 14 Photo detector 15 Photodetector 16 Ultraviolet light source device 17 Modulation region 18 Transparent substrate 19 Spacer 20 Recording layer

Claims (3)

(a) Three-dimensional cross-linked polymer matrix
(b) At least one of spiro orthoester, spiro ortho carbonate, cyclic carbonate, and bicycloorthoester
(c) an aluminum complex having a β-diketone having an alkyl group at the α-position carbon of the carbonyl group as a ligand
(d) A hologram recording medium comprising an organosilicon compound having a silanolic hydroxyl group.   The hologram recording medium according to claim 1, wherein the three-dimensional crosslinked polymer matrix is a cured product of an epoxy compound. (e) Radical polymerizable compound
3. The hologram recording medium according to claim 1, further comprising (f) a photo radical polymerization initiator.

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