JP2007139843A - Composition for hologram recording material, hologram recording medium and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a volume hologram recording material excellent in refractive index modulation, wavelength selectivity and durability; and also to provide a method for producing a hologram recording medium and a volume hologram. <P>SOLUTION: The photopolymer composition for a volume phase type hologram recording material contains a binder polymer (A) of formula (I) having a glass transition temperature of 40-200°C and a number average molecular weight of 10,000-1,000,000, a radically polymerizable substance (B) and a radical polymerization initiator (C), wherein R<SB>k</SB>and R<SB>l</SB>are each H or a saturated or unsaturated aliphatic hydrocarbon, alicyclic hydrocarbon, aromatic hydrocarbon or heteroaromatic hydrocarbon. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photopolymer composition for a volume phase hologram recording material, a method for producing a hologram recording medium using the composition, and a recording medium obtained by the method. More particularly, the present invention relates to a composition for a hologram recording material containing a vinyl carboxylate polymer having a high glass transition point as a binder polymer. The composition for a hologram recording material according to the present invention provides a hologram recording material having high durability and sufficient recording properties.

  The volume hologram records a light-dark interference pattern of light formed by light having high coherence (coherence) on a photosensitive material or the like by refractive index modulation.

  Volume holograms are widely used for design, security, and optical element applications because they can represent objects in three dimensions, have high diffraction efficiency, wavelength selectivity, and require advanced manufacturing technology. . Among these, dry photopolymers that do not require wet development are preferred because they can be used to produce volume holograms simply by dry processing.

  Such dry processing type volume hologram recording materials have been proposed in Patent Document 1, Patent Document 2, and the like. However, these materials did not reach the photosensitive materials requiring wet development processing in terms of refractive index modulation, which is a particularly important performance. For example, Patent Document 3 and Patent Document 4 have been proposed as improved techniques, but these use a non-reactive plasticizer or the like to improve the refractive index modulation ability. There was a problem with the film strength.

Thereafter, Patent Document 5 has been proposed in order to solve the above-mentioned problem. This is because an acid generator for curing a cationic polymerizable plasticizer is used, and an acid is contained in the produced hologram. Since it remained, it had a problem in durability, and the refractive index modulation was not sufficient.
US Pat. No. 3,658,526 US Pat. No. 3,993,485 US Pat. No. 4,942,102 US Pat. No. 4,942,112 Japanese Patent No. 2873126

  In order to solve the above-mentioned problems of the prior art, the present invention provides a composition for hologram recording material, a hologram recording medium, and a hologram recording medium capable of producing a volume hologram having excellent refractive index modulation, wavelength selectivity and durability. An object of the present invention is to provide a method for producing the volume hologram used.

The present invention is represented by the following general formula (I), in a photopolymer composition for a volume phase hologram recording material, having a glass transition temperature of 40 to 200 ° C. and a number average molecular weight of 10,000 to 1,000,000. The present invention relates to a composition for a holographic recording material comprising a binder polymer (A), a radical polymerizable substance (B), and a radical polymerization initiator (C).

R _k and R _l in the formula are the same or different and each represents a hydrogen atom, a saturated or unsaturated aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a heteroaromatic hydrocarbon group. These groups may have a halogen atom, a lower alkyl group, a lower alkoxy group, an aryl group, a nitro group, a lower alkylsilyl group, an acyl group or an ester group as a substituent. m and n are natural numbers and represent the number of repeating units, and are values such that the number average molecular weight of the binder polymer (A) falls within the range of 10,000 to 1,000,000.

  The preferred binder polymer (A) is poly (cyclohexanoyloxyethylene), poly (pivaloyloxyethylene) or poly (benzoyloxyethylene), which may have a substituent as described above. .

  The present invention also provides a recording layer comprising the above composition on the substrate by applying a hologram recording material composition having the above-described composition or a solution obtained by dissolving the composition in a solvent onto the substrate, evaporating the solvent. And a hologram recording medium obtained by the above-described manufacturing method.

  By using the volume hologram recording composition as described above, a volume hologram excellent in refractive index modulation, wavelength selectivity and durability can be easily produced.

  Next, the present invention will be described in more detail with reference to preferred embodiments of the present invention.

  First, the binder polymer (A) represented by the general formula (I) makes it possible to form a film for a composition for hologram recording material and to maintain interference fringes formed in the photosensitive layer by hologram recording. Used for. Therefore, this is closely related to the heat resistance and durability of the produced hologram. This also greatly affects refractive index modulation, which is a very important physical property in holograms.

  The binder polymer (A) has good compatibility with the radical polymerizable substance (B) and the radical polymerization initiator (C) and does not devitrify the photosensitive layer.

The saturated or unsaturated aliphatic hydrocarbon group as R _k and R ₁ in the general formula (I) is a saturated aliphatic hydrocarbon group, that is, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl Aliphatic hydrocarbon groups having carbon-carbon unsaturated groups such as carbon-carbon double bonds or carbon-carbon triple bonds such as vinyl, allyl, isopropenyl, butenyl, isobutenyl, pentenyl Alkenyl groups such as ethynyl, propynyl, butynyl, pentynyl and the like. Although R _k and the number of carbon atoms of the aliphatic hydrocarbon group as R _l is not specifically limited, preferably 1 to 30, more preferably from 1 to 20. The aliphatic hydrocarbon group may be cyclic, and the number of ring members is preferably 3 to 10, more preferably 5 to 7.

The aromatic hydrocarbon group as R _k and R ₁ in the general formula (I) is a monocyclic aromatic hydrocarbon group having 3 to 8 members or a polycyclic aromatic hydrocarbon in which two or more of them are condensed Groups such as phenyl, naphthyl, phenanthyl, anthranyl and the like.

The hetero atom of the aromatic heterocyclic group as R _k and R ₁ in the general formula (I) may be nitrogen, oxygen, sulfur, phosphorus, selenium and the like. The heterocyclic group may have a carbonyl group in the ring. Examples of the aromatic heterocyclic group include furyl, thienyl, imidazolyl, oxazolyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazolyl and the like.

  A saturated or unsaturated aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group or heteroaromatic hydrocarbon group is a halogen atom such as fluorine, chlorine or bromine, or a lower alkyl having 1 to 6 carbon atoms. Groups, lower alkoxy groups having 1 to 6 carbon atoms, aryl groups, nitro groups, mono-, di- or trialkylsilyl groups having 1 to 6 carbon atoms, acyl groups such as acetyl and toluoyl (alkanoyl, arylcarbonyl), propionyloxy, etc. The ester group (alkoxycarbonyl, aryloxycarbonyl, acyloxy) may be used as a substituent.

  The binder polymer (A) may be a homopolymer, a copolymer composed of several different repeating units, or a polymer blend in which two or more kinds of polymers are combined.

  Specific examples of the binder polymer (A) include poly (benzoyloxyethylene), poly (4-bromobenzoyloxyethylene), poly (3-bromobenzoyloxyethylene), poly (4-t-butylbenzoyloxyethylene), Poly (2-chlorobenzoyloxyethylene), poly (3-chlorobenzoyloxyethylene), poly (4-chlorobenzoyloxyethylene), poly (cyclohexanoyloxyethylene), poly (4-ethoxybenzoyloxyethylene), poly [(2-ethyl-2,3,3-trimethylbutyryloxy) ethylene], poly (isonicotinoyloxyethylene), poly (4-isopropylbenzoyloxyethylene), poly [(2-isopropyl-2,3- Dimethylbutyryloxy) ethylene], poly [(2 Methoxybenzoyloxy) ethylene], poly [(4-methoxybenzoyloxy) ethylene], poly [(4-methylbenzoyloxy) ethylene], poly [(1-methylcyclohexanoyloxy) ethylene], poly (nicotinoyloxy) Ethylene), poly [(3-nitrobenzoyloxy) ethylene], poly [(4-nitrobenzoyloxy) ethylene], poly [(4-phenylbenzoyloxy) ethylene], poly (pivaloyloxyethylene), poly [ (4-propionyloxybenzoyloxy) ethylene], poly [(2,2,3,3-tetramethylvaleryloxy) ethylene], poly [(trifluoroacetoxy) ethylene], poly [(3-trimethylsilylbenzoyloxy) Ethylene], poly [(4-trimethylsilylbenzoyloxy) ethylene], poly [ (1-acetylindazol-3-ylcarbonyloxy) ethylene], poly [(pentafluoropropionyloxy) ethylene], poly [(4-p-toluoylbutyryloxy) ethylene], poly [(undecafluorohexanoyl) One or more of these may be used.

  Examples of the binder polymer (A) that can be particularly preferably used include poly (cyclohexanoyloxyethylene), poly (pivaloyloxyethylene), and poly (benzoyloxy) ethylene.

  The amount of the binder polymer (A) used is preferably 10 to 85% by weight, more preferably 20 with respect to the total amount of the binder polymer (A), the radical polymerizable substance (B) and the radical polymerization initiator (C). ~ 70 wt%.

  Next, the radically polymerizable substance (B) used in the present invention only needs to have good compatibility with the binder polymer (A) and the radical polymerization initiator (C), and has an ethylenically unsaturated double bond. It may be selected from the group consisting of acrylate monomers, methacrylic monomers, vinyl monomers, and combinations of two or more thereof.

Examples of (meth) acrylic monomers include 2-hydroxyethyl (meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, ethoxyethylene glycol (meth) acrylate, methoxytriethylene glycol (meta ) Acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, 2,4,6-tribromophenoxy (meth) acrylate, 2-naphthyl (meth) acrylate, nonylphenol polyethylene glycol (meth) acrylate, tetrahydrofur Furyl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-acryloilo Cyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, neopentyl glycol acrylic acid benzoate, 9H-carbazole-9-ethyl (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, dimethylol-tricyclodecane di (meth) acrylate, ethylene oxide adduct di (meth) acrylate of bisphenol A, glycerin di (meth) acrylate Bisphenoxyethanol full orange (meth) acrylate, bis (4- (meth) acryloylthiophenyl) sulfide, pentaerythritol tri (meth) acrylate, tetramethylo Rumetantetora (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane acrylate benzoate, and the like. Further, it may be an oligomer having a dimer or trimer of the above compound.

Examples of vinyl monomers include vinyl acetate, 4-vinylaniline, 9-vinylanthracene, 9-vinylcarbazole, 4-vinylanisole, vinylbenzaldehyde, vinylbenzoate, vinylbenzyl chloride, 4-vinylbiphenyl, vinyl bromide, N- Vinyl caprolactam, vinyl chloroformate, vinyl crotonate, vinyl cyclohexane, 4-vinyl-1-cyclohexene diepoxide, vinyl cyclopentane, vinyl decanoate, 4-vinyl-1,3-dioxolan-2-one, vinyl carbo , Vinyl trithiocarbonate, vinyl 2-ethylhexanoate, vinyl ferrocene, vinylidene chloride, vinyl formate, 1-vinyl imidazole, 2-vinyl naphthalene, vinyl neodeca Noate, 5-vinyl-2-norbornene, 4- (vinyloxy) butylbenzoate, 2- (vinyloxy) ethanol, 4-vinylphenyl acetate, vinyl pivalate, vinyl propionate, 2-vinylpyridine, 1-vinyl-2-pyrrolidinone , Vinyl sulfone, vinyl trimethylsilane, bis (4-vinylthiophenyl) sulfide and the like. Further, it may be an oligomer having a dimer or trimer of the above compound.
Examples of (meth) allyl monomers include (meth) allylphenylsulfone, (meth) allylethoxysilane, (meth) allyltrimethoxysilane, (meth) allyl 2,4,6-tribromophenyl ether, 2,2 ′ -Di (meth) allylbisphenol A, di (meth) allyldimethylsilane, di (meth) allyldiphenylsilane, di (meth) allylphenylphosphine, di (meth) allyl phthalate, di (meth) allyl dicarbonate, Examples include di (meth) allyl succinate. Further, it may be an oligomer having a dimer or trimer of the above compound.

  Preferred as the radical polymerizable compound (B) are phenoxyethyl acrylate, 2,4,6-tribromophenoxy (meth) acrylate, 2-naphthyl (meth) acrylate, and ethylene oxide adduct di (meth) acrylate of bisphenol A. It is.

 The amount of the radical polymerizable compound (B) used is preferably 10 to 80% by weight, more preferably based on the total amount of the binder polymer (A), the radical polymerizable substance (B) and the radical polymerization initiator (C). Is 25-60% by weight.

  Next, examples of the radical polymerization initiator (C) used in the present invention include carbonyl compounds, organic tin compounds, alkylaryl boron salts, onium salts, iron arene complexes, trihalogenomethyl-substituted triazine compounds, organic peroxides. Bisimidazole derivatives, titanocene compounds and the like are used.

  Examples of the above compounds include benzyl, benzoin ethyl ether, benzophenone, diethoxyacetophenone, tributylbenzyltin, tetrabutylammonium / triphenylbutylborate, triphenyl-n-butylborate, diphenyliodonium salt, η5-cyclopentadienyl- η 6 -cumenyl-iron (1 +)-hexafluorophosphate (1-), tris (trichloromethyl) triazine, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, di-t- Butyl peroxyisophthalate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxybenzoate, 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2 '-Biimidazole, bis (2,4,5-triphenyl) imidazolyl, bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1) -Il) -phenyl) titanium. These may be used alone or in combination of two or more.

  The amount of the radical polymerization initiator (C) used is preferably 0.1 to 15% by weight based on the total amount of the binder polymer (A), the radical polymerizable substance (B) and the radical polymerization initiator (C). More preferably, it is 1 to 10% by weight.

 Moreover, you may use it combining a photosensitizing dye with a radical polymerization initiator (C) as needed.

  As photosensitizing dyes optionally used in the present invention, lasers used for hologram recording: He—Ne (wavelength 633 nm), Ar (wavelength 515, 488 nm), YAG (wavelength 532 nm) He—Cd (wavelength 442 nm), etc. Those that absorb the laser light are preferred, and among them, those that exhibit a spectral sensitizing action on the radical polymerization initiator (C) are more preferred.

  As such a photosensitizing dye, for example, mihiraketone, acridine yellow, merocyanine, methylene blue, camphorquinone, eosin, decarboxylated rose bengal and the like are preferably used. The photosensitizing dye is not particularly limited as long as it absorbs light in the visible region. For example, cyanine derivatives, merocyanine derivatives, phthalocyanine derivatives, xanthene derivatives, thioxanthene derivatives, acridine derivatives, porphyrin derivatives, coumarin derivatives. , Ketocoumarin derivatives, quinolone derivatives, stilbene derivatives, oxazine derivatives, thiazine dyes, etc. can also be used. Furthermore, “Dye Handbook” (Shin Okawara et al., Kodansha, 1986), “Chemicals of Functional Dyes” (Okawara) Photosensitizing dyes described in Shin et al., CMC, 1983) and “Special Function Materials” (Tadaburo Ikemori et al., CMC, 1986) can also be used. These may be used alone or in combination of two or more.

  Preferred examples of the photosensitizing dye include cyanine derivatives, merocyanine derivatives, ketocoumarin derivatives, and p-aminophenyl unsaturated ketones.

  Particularly preferred photosensitizing dyes include 2,5-bis (4-diethylaminobenzylidene) cyclopentanone and 2,5-bis [(4-diethylamino) -2-methylbenzylidene] cyclopentanone.

  The amount of the photosensitizing dye used is preferably 0.01 to 1% by weight, more preferably the total amount of the binder polymer (A), the radical polymerizable substance (B) and the radical polymerization initiator (C). 0.05 to 0.5% by weight.

The hologram recording material composition according to the present invention can contain additives such as a plasticizer, a thickener, a thermal polymerization inhibitor, a chain transfer agent, a solvent, and the like, if necessary.
The plasticizer is a compound that is non-reactive with the binder polymer (A), the radical polymerizable substance (B), and the radical polymerization initiator (C), and those having good compatibility are used. Examples of the plasticizer include phthalic acid esters represented by dimethyl phthalate, diethyl phthalate and dioctyl phthalate; dimethyl adipate, dibutyl adipate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate and diethyl succinate Basic acid esters; orthophosphates represented by trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tricresyl phosphate; acetates represented by glyceryl triacetate and 2-ethylhexyl acetate; triphenyl phosphite, dibutyl Inactive compounds such as phosphites represented by hydrogen phosphite are exemplified. The plasticizer may be used alone or in combination of two or more.
Thickeners should be compatible with binder polymer (A), radical polymerizable substance (B), radical polymerization initiator (C), and other additives to improve physical properties such as film strength. But use it.

  As the thickener, inorganic fine particles such as silica gel (for example, “Daiso Gel SP Series” manufactured by Daiso Corporation, “Silysia” and “Fuji Silica Gel” manufactured by Fuji Silysia Chemical Ltd., “Carplex” manufactured by Shionogi Pharmaceutical, Japan Aerosil “Aerosil”, Fuso Chemical Industries “ultra-high-purity colloidal silica”, “High-purity organosol”, Tokuyama's “Leolosil”, “Tocsil”, “Fine seal”, etc.) and organic fine particles (For example, diallyl phthalate polymers that can be produced by the methods described in JP-A-10-72510 and JP-A-10-310684, or “New Material Series“ Cutting-edge Technology of Ultrafine Particle Polymers ”” (CMC, Soichi Muroi "PB, 200 series" manufactured by Kao Corporation and "Belle Pearl" manufactured by Kanebo Co., Ltd. Leeds ", Sekisui Plastics Co., Ltd." tech polymer series ", Sekisui Fine Chemical Co., Ltd." Micro Pearl Series ", Soken Chemical & Engineering Co., Ltd.," MR Series "," MP Series ", etc.) is preferable.

  Some radical polymerization initiators (C) have poor storage stability, particularly dark storage stability. In that case, a thermal polymerization inhibitor may be used as a storage stabilizer.

  Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, t-butylcatechol, naphthylamine, diphenylpicrylhydrazine, diphenylamine and the like, which have a function of eliminating the generated polymerization active species.

  The chain transfer agent may be used to convert radicals generated from the radical polymerization initiator (C) into radicals with higher polymerization activity.

  Examples of chain transfer agents include α-methylstyrene dimer, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, dibenzothiazolyl disulfide, 2- (N, N-diethylthiocarbamoylthio) benzothiazole, 2- ( Morpholinodithio) benzothiazole and the like.

  The amounts of additives such as plasticizers, thickeners, thermal polymerization inhibitors, chain transfer agents and the like are appropriately selected according to the target hologram.

  The solvent is effective for improving the film-forming property in addition to the viscosity adjustment and compatibility adjustment, for example, acetone, xylene, toluene, methyl ethyl ketone, tetrahydrofuran, benzene, methylene chloride, dichloromethane, chloroform, methanol, etc. Organic solvents are often used. However, water cannot be used because it inhibits viscosity adjustment, compatibility adjustment, film-forming property, and the like. Water cannot be used as a medium even in emulsion form.

  The amount of the solvent used is preferably 1 to 1500 parts by weight with respect to 100 parts by weight as a total of the binder polymer (A), the radical polymerizable substance (B), the radical polymerization initiator (C), and the optional additives. Degree.

  In order to prepare the hologram recording material composition, for example, the binder polymer (A), the radical polymerizable substance (B), and the radical polymerization initiator (C) are put in an organic solvent resistant container such as a glass beaker, Is stirred. In this case, in order to promote the dissolution of the solid component, it may be heated to, for example, about 40 to 90 ° C. within a range in which the composition is not modified.

  In order to produce a hologram recording medium using the photopolymer composition for hologram recording material according to the present invention, the recording material composition is applied to one side of a substrate, and the resulting coating film, that is, two layers comprising a recording layer and a substrate. A recording medium having a structure is obtained. If necessary, a three-layer structure is obtained by covering a recording layer on the substrate with a film-like, sheet-like or plate-like protective material. It is preferable to use an organic solvent in the preparation process of the composition. In this case, the binder polymer (A), the radical polymerizable substance (B), and the radical polymerization initiator (C) are dissolved in a solvent, and the resulting solution is applied onto a substrate, and then the solvent is evaporated to form a recording layer. Form. When covering the recording layer with a protective material, it is preferable to remove the solvent by air drying, evaporation under reduced pressure or the like before coating the protective material. The substrate is made of an optically transparent material, for example, a glass plate, a polyethylene terephthalate plate, a polycarbonate plate, a plastic plate such as a polymethyl methacrylate plate, or a film. The thickness of the substrate is preferably 0.02 to 10 mm. The substrate does not have to be flat, and may be bent, curved, or have an uneven structure on the surface. The protective material is also made of an optically transparent material like the substrate. The thickness of the protective material is preferably 0.02 to 10 mm. Examples of the coating method include gravure coating, roll coating coating, bar coating coating, and spin coating coating. The thickness of the recording layer after removal of the solvent is 1 to 500 μm, preferably 1 to 100 μm.

  Using the hologram composition in the present invention, for example, a hologram can be produced by the following recording method.

  In order to record the recording object as a hologram on the hologram recording medium according to the present invention, a normal recording method can be adopted. That is, light having a wavelength in the range of 300 to 800 nm is divided into two, one of which (reference light) and the reflected light (object light) obtained by irradiating the object to be recorded with the other light beam. ) Are incident on the recording object from the same plane or from the front and back surfaces, and the hologram recording material medium is disposed at a position where interference fringes obtained by interference can be captured. Record the object in

More specifically, the laser beam is divided into two light beams by a beam splitter or the like, and interference fringes are obtained by using a mirror or the like to match the two again (two-beam exposure method). Alternatively, one laser beam is reflected by a mirror, and interference fringes are obtained by combining both incident light and reflected light again (single beam exposure method). A recording medium is installed at a position where the intensity distribution of the interference fringe pattern formed in this way can be captured. In this state, when laser light irradiation is normally performed for several seconds to several minutes, interference fringes that become holograms are recorded on the recording medium. The amount of laser light used is represented by the product of the light intensity and the irradiation time, and is preferably about 0.1 to 10,000 mJ / cm ² , more preferably about 1 to 1,000 mJ / cm ² .

 The light source used in the present invention is a light emitted from the light source to a photopolymerization initiation system comprising a radical polymerization initiator (C) and a combination of a radical polymerization initiator (C) and a photosensitizing dye that may optionally be added. What is necessary is just to induce the polymerization of the radically polymerizable substance (B) when it is irradiated. Typical examples of the light source include a high pressure mercury lamp, an ultra high pressure mercury lamp, a low pressure mercury lamp, a xenon lamp, a metal halide lamp, and a halogen lamp. These can be used when copying the information of the master hologram to the recording medium. They can also be used as a light source for fixing a hologram on which interference fringes are recorded. As a preferred light source for hologram recording, a laser can be mentioned. Since the laser has a single wavelength and has coherence, it is a light source suitable for hologram recording. A more preferable light source is a light source having further excellent coherence, for example, a laser in which an optical element such as an etalon is attached to the laser, which is obtained by changing the frequency of the single wavelength to a single frequency. Typical lasers have an oscillation wavelength of 300 to 800 nm, specifically Kr (wavelength 647 nm), He—Ne (wavelength 633 nm), Ar (wavelength 515 nm 488 nm), YAG (wavelength 532 nm), He—Cd (wavelength). 442 nm). These light sources may be used alone or in combination of two or more. Further, the light source may be continuous light or may oscillate in pulses at a constant or arbitrary interval. The light obtained from the light source may be applied to the recording material before and after recording as well as during recording.

After the hologram formation, it is preferable to post-polymerize the remaining unreacted radical polymerizable substance (B) by irradiating the entire surface with light. Examples of the light source used for the entire surface light irradiation include the high pressure mercury lamp, the ultra high pressure mercury lamp, the low pressure mercury lamp, the xenon lamp, the metal halide lamp, and the halogen lamp described above. The amount of light to be irradiated is usually about 0.1 to 10 J / cm ² . Moreover, you may heat-process in order to accelerate | stimulate polymerization as needed. Thereby, the diffraction efficiency, the peak wavelength of the diffracted light, the half width, etc. can be changed. As a method of heat treatment, it is preferable to put in an oven at about 40 to 150 ° C. for about 0.5 to 500 minutes. These post-treatments are also important for stabilizing the formed image and improving the weather resistance of the recorded hologram.

  Hereinafter, the present invention will be specifically described with reference to several examples of the present invention. However, these examples do not limit the present invention.

Example 1
1) Poly (pivaloyloxyethylene) was obtained as a binder polymer (A) by the following procedure.

  A 300 mL three-necked flask equipped with a stirrer, condenser and thermometer was charged with 32 g (0.25 mol) of pivaloyloxyethylene monomer and 13.3 g of methanol, and the temperature of the hot water bath was adjusted to 60 to 63 ° C. with stirring. Raised. After boiling started and reflux was observed, an initiator solution in which 0.16 g (1.00 mmol) of azobisisobutyronitrile was previously dissolved in 2.0 g of methanol was added. Since the polymerization started immediately, the polymerization was carried out for 5 hours.

  Then, a small amount of dinitrobenzene was added to terminate the polymerization, and heating was continued while dropwise adding methanol to distill unreacted pivaloyloxyethylene monomer together with methanol. When the temperature of the distillate reached the boiling point of methanol of 64.5 ° C., the purge was terminated. The reaction liquid mainly containing the polymer remaining after the monomer was driven out was poured into a large amount of water to precipitate, and further heated to remove a trace amount of residual monomer, followed by drying. The product polymer thus isolated was reprecipitated from a methanol-water system and purified.

2) 5.0 g of poly (pivaloyloxyethylene) (number average molecular weight = about 50,000) as the binder polymer (A), and phenoxyethyl acrylate (manufactured by Kyoei Chemical Co., Ltd., light acrylate PO-) as the radical polymerizable substance (B) A) 2.5 g, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone (manufactured by NOF Corporation, BTTB25 as a radical polymerization initiator (C), and toluene was distilled off. 0.30 g obtained by washing with ether), 0.030 g of 2,5-bis (4-diethylaminobenzylidene) cyclopentanone as a photosensitizing dye, and 20 g of acetone as a solvent are mixed at room temperature to obtain a hologram recording material composition. Prepared.

3) This composition was applied to one side of a 60 mm × 60 mm glass substrate (thickness: about 1.3 mm) by spin coating so that the thickness after drying was about 15 μm, and was subjected to heat treatment to remove the solvent from the coating layer. Then, a recording medium having a two-layer structure including a substrate and a recording layer made of the composition formed on the substrate was produced.

4) A hologram recording photosensitive plate having a three-layer structure was produced by covering the recording layer of this recording medium with a 50 μm thick PET film.

5) Next, an Ar ion laser of 515 nm was branched by a beam splitter, the angle of each branched light was changed by a mirror, and both were synthesized again to interfere with each other to obtain interference fringes. The photosensitive plate was placed at a position where the interference fringes could be captured so that light could enter from the glass surface.

6) An example of an optical system of a transmission hologram is shown in FIG.

7) In this state, the photosensitive plate was exposed, and interference fringes forming a hologram were recorded on the photosensitive plate. Beam intensity ratio is about 1: 1 to keep, one of the light intensity on the photosensitive plate as 1.0 mW / cm ^2, 60 seconds 5 seconds exposure as 10 mJ / cm ² from 120 mJ / cm ² was exposed.

8) For fixing the hologram latent image, the whole was irradiated from the PET film side with an exposure intensity of 10 mW / cm ² and an exposure amount of 3 J / cm ² using a high-pressure mercury lamp (USHIO, UM-102).

Example 2
1) In the same manner as in Example 1, poly (pivaloyloxyethylene) was obtained.

2) 5.0 g of poly (pivaloyloxyethylene) (number average molecular weight = about 50,000) as the binder polymer (A), and phenoxyethyl acrylate (manufactured by Kyoei Chemical Co., Ltd., light acrylate PO-) as the radical polymerizable substance (B) A) 2.0 g, tribromophenyl acrylate (Daiichi Kogyo Seiyaku Co., Ltd., New Frontier BR-30), 3,3 ′, 4,4′-tetra- (t-butylper) as radical polymerization initiator (C) Oxycarbonyl) benzophenone (manufactured by NOF Corporation, toluene distilled off from BTTB25 and washed with diethyl ether) 0.30 g, 2,5-bis (4-diethylaminobenzylidene) cyclopentanone as a photosensitizing dye 030 g and 20 g of acetone as a solvent were mixed at room temperature to prepare a hologram recording material composition.

  The operations in steps 3) to 8) were performed in the same manner as in Example 1.

Example 3
1) Poly (cyclohexanoyloxyethylene) was obtained as a binder polymer (A) in the same manner as (1) of Example 1. However, the amount of cyclohexanoyloxyethylene monomer was 39 g (0.25 mol).

2) 5.0 g of poly (cyclohexanoyloxyethylene) (number average molecular weight = about 40,000) as the binder polymer (A), paracumylphenoxyethylene glycol acrylate (manufactured by Toagosei Co., Ltd., Aronix) as the radical polymerizable substance (B) M-110) 3.5 g, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone (manufactured by NOF Corporation, BTTB25 as a radical polymerization initiator (C) 0.30 g, washed with diethyl ether), 0.030 g of a merocyanine dye (manufactured by Hayashibara Biochemical Laboratories, NK-1538) as a photosensitizing dye, and 20 g of acetone as a solvent are mixed at room temperature to obtain a hologram recording material composition A product was prepared.

  The operations in steps 3) to 8) were performed in the same manner as in Example 1.

Example 4
1) Poly (benzoyloxyethylene) was obtained as a binder polymer (A) in the same manner as (1) of Example 1. However, the amount of benzoyloxyethylene was 37 g (0.25 mol).

2) 5.0 g of poly (benzoyloxyethylene) (number average molecular weight = approximately 50,000) as the binder polymer (A), trimethylolpropane triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK Ester A) as the radical polymerizable substance (B) -TMPT) 2.5 g, 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone (manufactured by NOF Corporation, BTTB25 as a radical polymerization initiator (C), 0.30 g obtained by washing with diethyl ether), 0.030 g merocyanine dye (manufactured by Hayashibara Biochemical Laboratories, NK-1538) as photosensitizing dye, and 20 g acetone as solvent are mixed at room temperature to obtain a hologram recording material composition Was prepared.

  The operations in steps 3) to 8) were performed in the same manner as in Example 1.

Example 5
A hologram recording medium was prepared by the same operation as in Example 1, and a reflection hologram was recorded by the optical system shown in FIG.

Example 6
A hologram recording medium was manufactured by the same operation as in Example 2, and a reflection hologram was recorded by the optical system shown in FIG.

Example 7
A hologram recording medium was produced by the same operation as in Example 3, and a reflection hologram was recorded by the optical system shown in FIG.

Example 8
A hologram recording medium was produced by the same operation as in Example 4, and a reflection hologram was recorded by the optical system shown in FIG.

Comparative Example 1
2) Without using the binder polymer (A), 900 mg of 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (manufactured by Union Carbide, UVR-6110) as a cationic polymerizable compound, radical polymerizable compound As a binder polymer, 900 mg of bis (4-acryloxydiethoxyphenyl) methane, methyl methacrylate / ethyl acrylate / 2-hydroxypropyl methacrylate copolymer (copolymerization ratio 88/2/10, Mw = about 50,000) as a binder polymer, Photoradical polymerization initiator, diphenyliodonium hexafluoroantimonate 60 mg as a photocationic polymerization initiator, 3,9-diethyl-3′-carboxymethyl-2,2′-thiacarbocyanine, iodine salt 5 mg as a photosensitizing dye, A hologram recording material composition was prepared by mixing 1.5 g of ethanol to dissolve the photoradical polymerization initiator and photocationic polymerization initiator as a solvent, and 0.7 g of methyl ethyl ketone to dissolve other compositions at room temperature.

  The operations in steps 3) to 8) were performed in the same manner as in Example 1.

Comparative Example 2
2) Without using the binder polymer (A), 900 mg of Celoxide 2081 (manufactured by Daicel Chemical Industries) as the cationic polymerizable compound, 900 mg of bis (4-acryloxydiethoxyphenyl) methane as the radical polymerizable compound, and methyl methacrylate as the binder polymer / Ethyl acrylate / 2-hydroxypropyl methacrylate copolymer (copolymerization ratio 88/2/10, Mw = approximately 50,000) 500 mg, photoradical polymerization initiator, 60 mg diphenyliodonium hexafluoroantimonate as photocationic polymerization initiator 1,9-diethyl-3′-carboxymethyl-2,2′-thiacarbocyanine as a photosensitizing dye, 5 mg of an iodine salt, ethanol 1 to dissolve a photoradical polymerization initiator and a photocationic polymerization initiator as a solvent .5 , Methyl ethyl ketone 0.7g were mixed at room temperature to dissolve the other compositions were prepared hologram recording material composition.

  The operations in steps 3) to 8) were performed in the same manner as in Example 1.

Comparative Example 3
2) Without using the binder polymer (A), 900 mg of 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (manufactured by Union Carbide, UVR-6110) as a cationic polymerizable compound, radical polymerizable compound 2,2-bis (3,5-dibromo-4-methacryloxyethoxyphenyl) propane 450mg, bis (4-acryloxydiethoxyphenyl) methane 450mg, methyl methacrylate / ethyl acrylate / 2-hydroxypropyl methacrylate as binder polymer 500 mg of copolymer (copolymerization ratio 88/2/10, Mw = about 50,000), photoradical polymerization initiator, 60 mg of diphenyliodonium hexafluoroantimonate as a photocationic polymerization initiator, photosensitizing dye 3,9-diethyl-3′-carboxymethyl-2,2′-thiacarbocyanine, 5 mg of iodine salt, 1.5 g of ethanol to dissolve the photoradical polymerization initiator as the solvent, and the cationic photopolymerization initiator, and others In order to dissolve this composition, 0.7 g of methyl ethyl ketone was mixed at room temperature to prepare a hologram recording material composition.

  The operations in steps 3) to 8) were performed in the same manner as in Example 1.

Comparative Example 4
2) Without using the binder polymer (A), 900 mg of 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (manufactured by Union Carbide, UVR-6110) as a cationic polymerizable compound, radical polymerizable compound As a binder polymer, 900 mg of bis (4-acryloxydiethoxyphenyl) methane, methyl methacrylate / ethyl acrylate / 2-hydroxypropyl methacrylate copolymer (copolymerization ratio 88/2/10, Mw = about 50,000) as a binder polymer, 30 mg of 3,3 ′, 4,4′-tetra- (t-butylperoxycarbonyl) benzophenone (manufactured by NOF Corporation, distilled from BTTB25 and washed with diethyl ether) as a radical photopolymerization initiator, Photo cationic polymerization initiator 30 mg of triphenylsulfonium hexafluorophosphate, 3,9-diethyl-3′-carboxymethyl-2,2′-thiacarbocyanine as photosensitizing dye, 5 mg of iodine salt, photoradical polymerization initiator as solvent, and photo To dissolve the cationic polymerization initiator, 1.5 g of ethanol and 0.7 g of methyl ethyl ketone to dissolve other compositions were mixed at room temperature to prepare a hologram recording material composition.

  The operations in steps 3) to 8) were performed in the same manner as in Example 1.

Comparative Example 5
A hologram recording medium was manufactured in the same manner as in Comparative Example 1, and a reflection hologram was recorded with the optical system shown in FIG.

Comparative Example 6
A hologram recording medium was prepared by the same operation as in Comparative Example 2, and a reflection hologram was recorded by the optical system shown in FIG.

Comparative Example 7
A hologram recording medium was manufactured by the same operation as in Comparative Example 3, and a reflection hologram was recorded by the optical system shown in FIG.

Comparative Example 8
A hologram recording medium was manufactured in the same manner as in Comparative Example 1, and a reflection hologram was recorded with the optical system shown in FIG.

Hologram Performance Evaluation The transmission efficiency obtained in Examples 1 to 4 was measured for diffraction efficiency, diffraction incident angle, and transmission chromaticity, and performance evaluation was performed. Each measurement method is as follows.

  Further, refractive index modulation (a value that is half of the refractive index change of the interference fringes) was obtained by calculation. The calculation formula is “Coupled Wave Theory for Thick Hologram Gratings” [H. H. Kogelnik, Bell Sist Tech. (Bell Syst. Tech. J.) Volume 48, 2909-2947 (1969)] was used.

A) Diffraction efficiency The ratio of the incident light to the diffracted light was measured by an optical power meter (OPTICAL POWER / ENERGY METER, MODEL 66XLA, manufactured by PHOTODYNE).

Diffraction efficiency (%) = (diffracted light intensity / incident light intensity) × 100
B) Diffraction incident angle The diffraction incident angle was defined as the incident angle of the reproduction light when the diffraction efficiency was maximized.

C) Transmission chromaticity The transmission chromaticity of the hologram was measured by measuring CIE1976L ^* a ^* b ^* color system a ^* and b ^{* using} a color difference meter (Nippon Denshoku Industries Co., Ltd., Z-Σ90 COLOR MEASURING SYSTEM). The chromaticity was determined.

Transmission chromaticity c ^* = (a ^{* 2} + b ^{* 2} ) ^1/2
The obtained results are shown in Table 1.

  All the transmission holograms exhibit refractive index modulation within a sufficiently practical range. In addition, the transmission chromaticity values are all small, and are highly colorless and transparent.

  The reflection holograms obtained in Examples 5 to 8 were measured for transmittance using an ultraviolet-visible spectrophotometer (“V-550” manufactured by JASCO Corporation), and diffraction efficiency, reproduction wavelength, and visible light transmission were measured. The rate was calculated and the performance was evaluated. Each calculation method will be described with reference to FIG.

  When the transmittance measurement is performed on the obtained reflection hologram using an ultraviolet-visible spectrophotometer, a chart as shown in FIG. 3 is obtained. In the figure, (T) is the visible light transmittance, (R) is the intensity of the diffracted light, and (λ) where the intensity of the diffracted light is (R) is the reproduction wavelength. The diffraction efficiency of the reflection hologram was calculated from the ratio of the intensity of diffracted light to the visible light transmittance other than the reproduction wavelength, as shown in the following equation.

Diffraction efficiency (%) = diffracted light intensity (P) / visible light transmittance (T) × 100
Further, refractive index modulation (a value that is half of the refractive index change of the interference fringes) was obtained by calculation. The calculation formula is “Coupled Wave Theory for Thick Hologram Gratings” [H. H. Kogelnik, Bell Sist Tech. (Bell Syst. Tech. J.) Volume 48, 2909-2947 (1969)] was used.

The obtained results are shown in Table 2.

  All of the reflection holograms exhibit refractive index modulation within a sufficiently practical range. In addition, the visible light transmittance is sufficiently high, and in addition, the recording wavelength of 515 nm can be recorded almost faithfully.

Diffraction efficiency, diffraction incident angle, and transmission chromaticity were also measured for the transmission holograms obtained in Comparative Examples 1 to 4, and performance evaluation was performed. The results are shown in Table 3.

  Compared with the transmission type holograms of Examples 1 to 4, it can be seen that the refractive index modulation is small. In addition, the numerical value of transmission chromaticity tends to be high.

Also for the reflection type holograms obtained in Comparative Examples 5 to 8, transmittance measurement was performed to determine diffraction efficiency, reproduction wavelength, and visible light transmittance, and performance evaluation was performed. The results are shown in Table 4.

  Compared with the reflection type holograms of Examples 5 to 6, it can be seen that the refractive index modulation is small. The visible light transmittance is almost the same. It can be seen that the reproduction wavelength is shifted slightly longer in Comparative Example 5.

Durability Evaluation In order to compare the durability between the hologram according to the present invention and that according to the prior art, a heat resistance test and a weather resistance test were performed by the following methods.

A) Heat resistance test The three-layer structure [glass substrate / hologram layer / protective layer (PET)] obtained in each step 4 of Examples and Comparative Examples was placed in a circulation oven at 85 ° C. for 500 hours. Changes in diffraction efficiency and transmission chromaticity were examined for transmission holograms, and changes in diffraction efficiency and reproduction wavelength were examined for reflection holograms.

  The test results are shown in Tables 5 and 6 below.

B) Weather resistance test A three-layer structure [glass substrate / hologram layer / protective layer (PET)] obtained in each step 4 of Examples and Comparative Examples was subjected to a xenon lamp (manufactured by USHIO INC., UI- 501C, 300 W), and irradiation was performed with an intensity of 10 mW / cm ² and an exposure amount of 500 J / cm ² . Changes in diffraction efficiency and transmission chromaticity were examined for transmission holograms, and changes in diffraction efficiency and reproduction wavelength were examined for reflection holograms.

The hologram of the example has a smaller transmission chromaticity value and the amount of change compared to that of the comparative example. On the other hand, the hologram of the comparative example had a large change in transmission chromaticity in both the heat resistance test and the weather resistance test, and the hologram was very yellowish. This is considered to be due to the presence of acid in the hologram layer.

  In the hologram of the example, both the diffraction efficiency and the change in the reproduction wavelength are small. On the other hand, it can be seen that the hologram of the comparative example has a large change in the reproduction wavelength in the heat resistance test. This is presumably because many unreacted reactive components remain in the hologram even after the fixing process, so that the interference fringes formed in the recording medium cannot be maintained.

  In the present invention, a binder polymer (A) represented by the general formula (I), having a glass transition point of 40 ° C. or higher and a number average molecular weight of 10,000 or higher, a radical polymerizable substance (B), a radical polymerization initiator ( By using the volume hologram recording composition containing C), a hologram excellent in refractive index modulation, wavelength selectivity and durability can be easily produced.

  Therefore, this makes it possible to use the hologram for every application such as a design application, a security application, and an optical element application.

It is the schematic which showed the example of the optical system for transmission type hologram recording. It is the schematic which showed the example of the optical system for reflection type hologram recording. It is the conceptual diagram which showed the calculation method of the diffraction efficiency of a reflection type hologram.

Explanation of symbols

(LASER) is a laser generator,
(BS) is a beam splitter,
(M) is a mirror,
(S) is a photosensitive material,
(T) is the visible light transmittance,
(R) is the intensity of the diffracted light,
(λ) is the reproduction wavelength, which is the wavelength at which the diffracted light intensity (R) is maximum.

Claims (4)

In the photopolymer composition for volume phase hologram recording material, a binder polymer represented by the following general formula (I) having a glass transition temperature of 40 to 200 ° C. and a number average molecular weight of 10,000 to 1,000,000 ( A composition for a hologram recording material, comprising A), a radical polymerizable substance (B), and a radical polymerization initiator (C).

R _k and R _l in the formula are the same or different and each represents a hydrogen atom, a saturated or unsaturated aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a heteroaromatic hydrocarbon group. These groups may have a halogen atom, a lower alkyl group, a lower alkoxy group, an aryl group, a nitro group, a lower alkylsilyl group, an acyl group or an ester group. m and n are natural numbers and represent the number of repeating units. The composition for a hologram recording material according to claim 1, wherein the binder polymer (A) is poly (cyclohexanoyloxyethylene), poly (pivaloyloxyethylene) or poly (benzoyloxyethylene). Hologram recording wherein a composition for a hologram recording material according to claim 1 or 2 or a solution obtained by dissolving the composition in a solvent is applied onto a substrate, the solvent is evaporated, and a recording layer comprising the composition is formed on the substrate. A method for manufacturing a medium. A hologram recording medium obtained by the manufacturing method according to claim 3.

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