JP2009122266A - Squarylium compound containing volume hologram recording photosensitive composition for short wavelength light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a volume hologram recording photosensitive composition having an excellent sensitivity to the light in the wavelength range of a short wavelength light source. <P>SOLUTION: The symmetrical squarylium compound is expressed by general formula (I), where R<SP>1</SP>and R<SP>2</SP>are the same or different from each other and represent; alkyl groups which may have a substitution group alkoxyl groups which may have a substitution group aralkyl groups which may have a substitution group heterocycle alkyl groups which may have a substitution group aryl groups which may have a substitution group heterocycle groups which may have a substitution group or alternatively each of R<SP>1</SP>and R<SP>2</SP>can form a heterocycle group together with its adjoining nitrogen atoms. The volume hologram recording photosensitive composition contains the symmetrical squarylium compound, a polymerized monomer, and a radical generating agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photosensitive composition for volume hologram recording for a short wavelength light source, which contains a squarylium compound.

An optical recording medium is one of recording media capable of writing a large amount of information such as high-density image data. As a typical optical recording medium, a two-dimensional recording medium such as a CD-R is known. For this two-dimensional recording medium, attempts have been made to shorten the wavelength of the recording laser so as to increase the recording capacity. As a result, CD (λ = 780 nm), DVD (λ = 650 nm), HD -Higher recording capacity is realized in the order of DVD / Blu-ray Disk (405 nm). However, further shortening of the wavelength of the recording laser is difficult in terms of the resin material, and in order to achieve further higher recording capacity, a method different from this two-dimensional recording is required. .
In recent years, a volume hologram recording method capable of recording information three-dimensionally has attracted attention. By using this method, a high recording capacity at the TB level is expected. Among them, a technique using a short wavelength light source (330 to 450 nm) that can be expected to have a high recording capacity is particularly attracting attention.

In general, as a photosensitive composition for volume hologram recording, a composition mainly composed of a radical polymerizable monomer, a binder resin, a radical generator, and a sensitizing dye is known.
Examples of using a squarylium compound as a sensitizing dye for a volume hologram recording photosensitive composition so far include an example using a visible light region (600 to 700 nm) laser as a light source (Patent Document 1), and And an example using a YAG laser (532 nm) (Patent Document 2). However, an example using a short wavelength light source laser (330 to 450 nm) capable of realizing higher recording capacity has not been reported yet.
JP 5-5005 JP2007-57965A

  An object of this invention is to provide the photosensitive composition for volume type hologram recording which has the outstanding sensitivity with respect to the light of the wavelength range of a short wavelength light source.

（式中、Ｒ^１およびＲ^２は、同一または異なって、置換基を有していてもよいアルキル基、置換基を有していてもよいアルコキシル基、置換基を有していてもよいアラルキル基、置換基を有していてもよい複素環アルキル基、置換基を有していてもよいアリール基、または置換基を有していてもよい複素環基を表すか、あるいはＲ^１とＲ^２はそれぞれが隣接する窒素原子と一緒になって複素環基を形成してもよい）で表される対称型スクアリリウム化合物、重合性モノマー、およびラジカル発生剤を含む体積型ホログラム記録用感光性組成物。

［２］ Ｒ^１が置換基を有してもよいアリール基を表し、およびＲ^２が置換基を有していてもよいアルキル基または置換基を有していてもよいアラルキル基を表すか、あるいは、Ｒ^１とＲ^２が隣接する窒素原子と一緒になって置換基を有してもよい複素環を形成してもよい対称型スクアリリウム化合物を含む［１］記載の体積型ホログラム記録用感光性組成物。

［３］ 対称型スクアリリウム化合物が３３０nm〜４５０nmの波長領域に最大吸収波長を有する［２］記載の体積型ホログラム記録用感光性組成物。 The present invention provides the following [1] to [4].

[1] General formula (I)

(In the formula, R ¹ and R ² are the same or different and each may have an alkyl group which may have a substituent, an alkoxyl group which may have a substituent, or an aralkyl which may have a substituent. Represents a group, a heterocyclic alkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent, or R ¹ and R ² may each form a heterocyclic group together with the adjacent nitrogen atom), and a photosensitive composition for volume hologram recording, comprising a symmetric squarylium compound represented by: a polymerizable monomer, and a radical generator object.

[2] R ¹ represents an aryl group which may have a substituent, and R ² represents an alkyl group which may have a substituent or an aralkyl group which may have a substituent, Alternatively, the photosensitive composition for volume hologram recording according to [1], comprising a symmetric squarylium compound in which R ¹ and R ² together with the adjacent nitrogen atom may form a heterocyclic ring which may have a substituent. Sex composition.

[3] The photosensitive composition for volume hologram recording according to [2], wherein the symmetrical squarylium compound has a maximum absorption wavelength in a wavelength region of 330 nm to 450 nm.

  According to the present invention, by using a squarylium compound as a sensitizing dye, it is possible to provide a photosensitive composition for volume hologram recording for a short wavelength light source that has excellent sensitivity and excellent photobleaching properties (bleaching characteristics). it can.

Hereinafter, the compound represented by formula (I) is referred to as compound (I). The same applies to compounds with other formula numbers.
In the definition of each group in the general formula, examples of the alkyl moiety in the alkyl group and the alkoxyl group include a linear or branched alkyl group having 1 to 6 carbon atoms or a cyclic alkyl group having 3 to 8 carbon atoms, Specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, 2-methylbutyl group, tert-pentyl group, hexyl Group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group and the like.
Examples of the aralkyl group include an aralkyl group having 7 to 15 carbon atoms, and specific examples include a benzyl group, a phenethyl group, a phenylpropyl group, and a naphthylmethyl group.
Examples of the aryl group include a phenyl group, a naphthyl group, and an anthryl group.
Examples of the heterocyclic group include an aromatic heterocyclic group and an alicyclic heterocyclic group.

  As the aromatic heterocyclic group, for example, a 5- or 6-membered monocyclic aromatic heterocyclic group containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and a 3- to 8-membered ring are condensed. A bicyclic or tricyclic fused ring aromatic heterocyclic group containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and more specifically, a pyridyl group, a pyrazinyl group, Pyrimidinyl, pyridazinyl, quinolyl, isoquinolyl, phthalazinyl, quinazolinyl, quinoxalinyl, naphthyridinyl, cinnolinyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, tetrazolyl, thienyl, furyl, thiazolyl , Oxazolyl group, indolyl group, isoindolyl group, indazolyl group, benzimidazolyl group, ben Triazolyl, benzothiazolyl, benzoxazolyl, purinyl, carbazolyl group and the like.

  Examples of the alicyclic heterocyclic group include a 5-membered or 6-membered monocyclic alicyclic heterocyclic group containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and a 3- to 8-membered ring. And a condensed alicyclic heterocyclic group containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and more specifically a pyrrolidinyl group, Piperidyl group, piperazinyl group, morpholinyl group, thiomorpholinyl group, homopiperidyl group, homopiperazinyl group, tetrahydropyridyl group, tetrahydroquinolyl group, tetrahydroisoquinolyl group, tetrahydrofuryl group, tetrahydropyranyl group, dihydrobenzofuranyl group, tetrahydro And a carbazolyl group.

  Examples of the substituent of the alkyl group and the alkoxyl group include the same or different 1 to 3 substituents, specifically, a hydroxyl group, a carboxyl group, a halogen atom, an alkoxyl group, an alkoxyalkoxyl group, and a trifluoromethyl group. And a trifluoromethoxy group. Here, the alkyl part in the alkoxyl group has the same meaning as described above. The alkyl part of the alkoxyalkoxyl group has the same meaning as described above, and the alkylene part has the same meaning as that obtained by removing one hydrogen atom from the lower alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

  Examples of the substituent of the aralkyl group, aryl group, heterocyclic group, benzyl group, and phenyl group are the same or different and are 1 to 5 substituents, specifically, hydroxyl group, carboxyl group, halogen atom, alkyl Group, alkoxyl group, nitro group, alkyl-substituted or unsubstituted amino group, benzoyl group, trifluoromethyl group, trifluoromethoxy group and the like. Here, the alkyl part in a halogen atom, an alkyl group, and an alkoxyl group is respectively synonymous with the above. The alkyl part of the alkyl-substituted amino group has the same meaning as the alkyl group. When the alkyl-substituted amino group is an amino group substituted with two alkyl groups, the two alkyl groups may be the same or different.

For example, compound (I) can be produced as follows.
Reaction formula 1

[Wherein R ¹ and R ² are as defined above]

Reaction formula 1
Compound (I) was obtained by reacting Compound (II) with 2 to 5 moles of Compound (III) in a solvent at 25 to 130 ° C. for 1 to 100 hours, and then collecting the precipitate by filtration. It is obtained by washing with a solvent and drying.
Examples of the solvent include alcohol solvents such as ethanol, propanol, 2-propanol, butanol, and octanol, or a mixed solvent of the alcohol solvent (50% by volume or more) and benzene, toluene, or xylene.
After the reaction, if necessary, the target compound may be purified by methods usually used in organic synthetic chemistry (various chromatographic methods, recrystallization methods, or distillation methods).

  Below, the preferable specific example of compound (I) is illustrated.

As the radical generator, s-triazine compounds substituted with at least one trihalomethyl group [2,4,6-tris (trichloromethyl) -s-triazine, 2- (4-methoxyphenyl) -4,6 -Bis (trichloromethyl) -s-triazine, 2- (4-methoxy-1-naphthalenyl) -4,6-bis (trichloromethyl) -s-triazine, etc.], organic peroxides [3,3 ′, 4,4′-tetrakis (t-butyldioxycarbonyl) benzophenone (hereinafter referred to as BTTB), etc.], N-phenylglycines (N-phenylglycine, p-chloro-N-phenylglycine, m-methyl-N -Phenylglycine, etc.), aromatic sulfonyl halide compounds (benzenesulfonyl chloride, p-toluenesulfonyl chloride, etc.), imidazole Mer acids [2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole and the like], iron arene complexes [eta ⁶ - benzene) (eta ⁵ - Shikuropentaji PF ₆ enyl) iron (II) ^- salt, etc.], titanocene (fluoroaryl titanocene etc.), diaryl iodonium salts, triaryl sulfonium salts, branched polyethylene imines, and the like. The amount of the radical generator used in the photosensitive composition for volume hologram recording of the present invention is 0.1 to 100 parts, preferably 1 to 1 part by weight of the sensitizing dye (hereinafter referred to as part by weight). 50 parts

Next, the photosensitive composition for volume hologram recording in the present invention will be described. The photosensitive composition for volume hologram recording is composed of a polymerizable monomer, a radical generator, a sensitizer, and a binder resin, a general additive (for example, a plasticizer, a solvent, a thermal polymerization inhibitor, a viscosity, if necessary). It is prepared by mixing adjusting agents and the like.
The polymerizable monomer of the present invention is cured by addition polymerization by the action of a photodegradation product generated when the radical generator is exposed to actinic rays in the presence of a sensitizing dye, and is substantially insolubilized. It is a monomer having an ethylenically unsaturated double bond or a polymer having an ethylenically unsaturated double bond in the main chain or side chain.
Examples of the monomer having an ethylenically unsaturated double bond include an unsaturated carboxylic acid, an ester of an unsaturated carboxylic acid and an aliphatic polyhydroxy compound, an ester of an unsaturated carboxylic acid and an aromatic polyhydroxy compound, Examples thereof include esters obtained by an esterification reaction of an unsaturated carboxylic acid, a polyvalent carboxylic acid and a polyhydroxy compound.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid and the like. Examples of esters of unsaturated carboxylic acids and aliphatic polyhydroxy compounds include ethylene glycol diacrylate, triethylene glycol diacrylate, trimethylol propane triacrylate, trimethylol ethane triacrylate, pentaerythritol diacrylate, pentaerythritol tris. Acrylate esters such as acrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, glycerol acrylate; triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate , Pentaerythritol dimethacryl Methacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate, etc .; other itaconic acid esters of aliphatic polyhydroxy compounds, crotonic acid Examples thereof include esters and maleic esters.

Examples of the ester of an unsaturated carboxylic acid and an aromatic polyhydroxy compound include hydroquinone diacrylate, hydroquinone dimethacrylate, resorcin diacrylate, resorcin dimethacrylate, pyrogallol triacrylate, and the like. Examples of the ester obtained by esterification reaction of unsaturated carboxylic acid, polyvalent carboxylic acid and polyhydroxy compound include condensates of acrylic acid, phthalic acid and ethylene glycol; condensation of acrylic acid, maleic acid and diethylene glycol. A condensate of methacrylic acid, terephthalic acid and pentaerythritol; a condensate of acrylic acid, adipic acid, butanediol and glycerin.
Examples of other compounds having an ethylenically unsaturated double bond used in the present invention include acrylamides such as ethylene bisacrylamide, allyl esters such as diallyl phthalate and prepolymers thereof, vinyl group-containing compounds such as divinyl phthalate, etc. Can be given. Examples of the polymer having an ethylenically unsaturated double bond in the main chain include polyester obtained by polycondensation reaction of unsaturated divalent carboxylic acid and dihydroxy compound, polycondensation reaction of unsaturated divalent carboxylic acid and diamine. And the polyamide obtained by the above.

  Examples of the polymer having an ethylenically unsaturated double bond in the side chain include divalent carboxylic acids having an unsaturated bond in the side chain, such as itaconic acid, propylidene succinic acid, ethylidene malonic acid and the like, and dihydroxy or diamine. Examples thereof include condensation polymers with compounds. Further, polymers having a functional group such as a hydroxy group or a methyl halide group in the side chain, such as polyvinyl alcohol, poly (2-hydroxyethyl methacrylate), epoxy resin, phenoxy resin polyepichlorohydrin, acrylic acid, methacrylic acid, Examples thereof include a polymer obtained by a polymer reaction with an unsaturated carboxylic acid such as crotonic acid.

  Examples of the binder resin include polymethacrylic acid esters or partial hydrolysates thereof, polyacrylic acid esters or partial hydrolysates thereof, polystyrene, polyvinyl acetate or partial hydrolysates thereof, polyvinyl butyral, polychloroprene, and polyvinyl chloride. , Chlorinated polyethylene, chlorinated polypropylene, polyvinyl pyrrolidone, polyethylene oxide, polymethacrylic acid or methacrylic acid copolymer having a carboxyl group in the side chain, polyacrylic acid or acrylic acid copolymer having a carboxyl group in the side chain, polyurethane , Polyamide, polycarbonate, acetyl cellulose, polyvinyl carbazole, other acrylates, methacrylates, (anhydrous) maleic acid, acrylonitrile, styrene, vinyl acetate, salts Vinyl, vinylidene chloride, butadiene, isoprene, copolymers such as chloroprene and the like.

Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and isononyl phthalate, dimethyl adipate, dibutyl adipate, dimethyl sebacate, diethyl sebacate, and sebacine. Aliphatic dibasic acid esters such as dibutyl acid and diethyl succinate, orthophosphoric acid esters such as trimethyl phosphate, triethyl phosphate, triphenyl phosphate and tricresyl phosphate, acetate esters such as glyceryl triacetate and 2-ethylhexyl acetate Phosphites such as triphenyl phosphite and dibutyl hydrogen phosphite.
The photosensitive medium for volume hologram recording can be obtained by applying the above-described photosensitive composition for volume hologram recording to a substrate as a coating liquid. When the viscosity of the composition is high, It can also be obtained by applying a solution obtained by dissolving the composition in a solvent as a coating solution, applying the solution on a substrate, and drying.

  The solvent is not particularly limited as long as it can dissolve the photosensitive composition for volume hologram recording. For example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, and cyclohexanone. Ether solvents such as diethyl ether, methyl tertiary butyl ether, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, propylene glycol monomethyl ether Glycol ether solvents such as acetate, alcohol solvents such as ethanol, propanol, 2-propanol, butanol, Ester solvents such as ethyl acetate, propyl acetate and butyl acetate, aromatic solvents such as benzene, toluene, xylene and chlorobenzene, chloro solvents such as 1,2-dichloroethane, dichloromethane and chloroform, or mixed solvents thereof can give.

  The base material to which the coating liquid is applied is not particularly limited as long as it has transparency, but a glass substrate or a plastic substrate is desirable. Examples of the plastic substrate include polyethylene, polypropylene, polyvinyl fluoride, polyvinylidene fluoride, polyvinyl chloride, polyvinylidene chloride, ethylene-vinyl alcohol, polyvinyl alcohol, polymethyl methacrylate, polyether sulfone, polyether ether ketone, polyamide. And resins such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyethylene terephthalate and polyimide film.

  In the volume hologram recording photosensitive medium, the thickness of the volume hologram material obtained by drying or melting the coating liquid is preferably in the range of 1 to 2,000 μm, more preferably 10 to 1,000 μm. Range. Therefore, it is preferable that the thickness of the coating solution for applying the coating solution on the substrate is appropriately adjusted according to this. Further, the thickness of the base material is not particularly limited, but from the viewpoint of ensuring transparency, the thickness is preferably in the range of 0.1 mm to 5 mm, and more preferably in the range of 0.3 to 2 m. It is.

A conventional technique can be used as a method of applying the coating liquid onto the substrate, and for example, a spin coater, a gravure coater, a bar coater, or the like can be used. If the viscosity of the coating liquid is low, for example, the coating liquid is sandwiched between a pair of substrates (for example, a glass substrate), and the periphery of the pair of substrates is sealed to make a volume hologram recording photosensitive. Can be produced.
Hologram recording is performed on the photosensitive medium for volume hologram recording by causing information light and reference light to interfere with each other inside the recording layer. The hologram to be recorded may be either a transmission hologram or a reflection hologram. The interference method between the information beam and the reference beam may be either a two-beam interference method or a coaxial interference method.

  The light source used for recording the hologram may be a short wavelength (350 to 450 nm), and examples include a semiconductor laser (wavelength 405 nm), a YAG laser (THG) (wavelength 355 nm), and a He-Cd laser (wavelength). 442 nm) and the like. Further, in order to complete the polymerization reaction, after the interference exposure, a process such as full exposure with ultraviolet rays or heating may be appropriately performed.

[Example]
Hereinafter, the present invention will be described more specifically with reference to examples and test examples.

(Production of Compound 1)
1.40 g of 3,4-dihydroxycyclobutene-1,2-dione and 4.87 g of Nn-butylaniline are added to a mixed solvent of butanol 8.0 ml and toluene 8.0 ml and reacted at 130 ° C. for 30 hours. It was. Thereafter, the precipitated yellowish white solid was collected by filtration to obtain Compound 1 (1.64 g).
¹ H-NMR, 400 MHz, δ (DMSO-d ₆ ) ppm: 0.82 (6H, s (broad)), 1.28 (4H, s (broad)), 1.47 (4H, s (broad)) ), 4.31 (4H, s (broad)), 7.29-7.41 (10H, m).
Maximum absorption wavelength (CHCl ₃ ): 369.0 nm
Molar extinction coefficient (CHCl ₃ ): 36400 (mol / l) ⁻¹ · cm ⁻¹

(Production of Compound 2)
2.00 g of 3,4-dihydroxycyclobutene-1,2-dione and 6.81 g of N-sec-butylaniline are added to a mixed solvent of butanol 8.0 ml and toluene 8.0 ml and reacted at 130 ° C. for 30 hours. It was. Thereafter, the precipitated yellowish white solid was collected by filtration to obtain Compound 2 (1.50 g).
¹ H-NMR, 400 MHz, δ (DMSO-d ₆ ) ppm: 0.92 (6H, t, J = 7.2 Hz), 1.23 (6H, m), 1.51-1.71 (4H, m), 4.66 (2H, s (broad)), 7.23-7.38 (10H, m).
Maximum absorption wavelength (CHCl ₃ ): 348.0 nm
Molar extinction coefficient (CHCl ₃ ): 33400 (mol / l) ⁻¹ · cm ⁻¹

(Production of Compound 3)
2.00 g of 3,4-dihydroxycyclobutene-1,2-dione and 9.62 g of N-benzylaniline were added to a mixed solvent of butanol 8.0 ml and toluene 8.0 ml, and reacted at 130 ° C. for 14 hours. Thereafter, the precipitated yellowish white solid was collected by filtration to obtain Compound 3 (7.13 g).
¹ H-NMR, 400 MHz, δ (DMSO-d ₆ ) ppm: 5.60 (4H, s), 7.25-7.34 (20H, m).
Maximum absorption wavelength (CHCl ₃ ): 369.0 nm
Molar extinction coefficient (CHCl ₃ ): 37100 (mol / l) ⁻¹ · cm ⁻¹

(Production of Compound 4)
2.00 g of 3,4-dihydroxycyclobutene-1,2-dione and 6.99 g of 1,2,3,4-tetrahydroquinoline are added to a mixed solvent of 8.0 ml of butanol and 8.0 ml of toluene at 130 ° C. The reaction was carried out for 14 hours. Thereafter, the precipitated orange solid was collected by filtration to obtain Compound 4 (5.73 g).
¹ H-NMR, 400 MHz, δ (DMSO-d ₆ ) ppm: 2.05 (4H, t, J = 5.6 Hz), 2.89 (4H, t, J = 6.6 Hz), 4.34 ( 4H, t, J = 5.6 Hz), 7.12-7.23 (6H, m), 7.47 (2H, d, J = 8.1 Hz).
Maximum absorption wavelength (CHCl ₃ ): 403.0 nm
Molar extinction coefficient (CHCl ₃ ): 47000 (mol / l) ⁻¹ · cm ⁻¹

(Production of Compound 5)
2.00 g of 3,4-dihydroxycyclobutene-1,2-dione and 9.20 g of N-cyclohexylaniline were added to a mixed solvent of 8.0 ml of butanol and 8.0 ml of toluene and reacted at 130 ° C. for 20 hours. Thereafter, the precipitated white solid was collected by filtration to obtain Compound 5 (5.16 g).
¹ H-NMR, 400 MHz, δ (DMSO-d ₆ ) ppm: 0.95-1.91 (20H, m), 4.44 (2H, m), 7.23-7.35 (10H, m) .
Maximum absorption wavelength (CHCl ₃ ): 346.5.
Molar extinction coefficient (CHCl ₃ ): 32400 (mol / l) ⁻¹ · cm ⁻¹

(Production of Compound 6)
2.00 g of 3,4-dihydroxycyclobutene-1,2-dione and 7.89 g of N-ethyl-m-toluidine are added to a mixed solvent of butanol 8.0 ml and toluene 8.0 ml and reacted at 130 ° C. for 20 hours. I let you. Thereafter, the precipitated yellow solid was collected by filtration to obtain Compound 6 (1.94 g).
¹ H-NMR, 400 MHz, δ (DMSO-d ₆ ) ppm: 1.15 (6H, t, J = 7.1 Hz), 2.32 (6H, s), 4.29 (4H, q, J = 7.1 Hz), 7.10-7.30 (8H, m).
Maximum absorption wavelength (CHCl ₃ ): 369.5 nm
Molar extinction coefficient (CHCl ₃ ): 33000 (mol / l) ⁻¹ · cm ⁻¹

(Production of Compound 7)
2.00 g of 3,4-dihydroxycyclobutene-1,2-dione and 6.17 g of N-ethyl-0-toluidine are added to a mixed solvent of butanol 8.0 ml and toluene 8.0 ml and reacted at 130 ° C. for 30 hours. I let you. Thereafter, the precipitated yellow solid was collected by filtration to obtain Compound 7 (2.04 g).
¹ H-NMR, 400 MHz, δ (DMSO-d ₆ ) ppm: 1.05-1.15 (6H, m), 2.15-2.11 (6H, m), 4.03-4.14 ( 4H, m), 7.23-7.32 (8H, m).
Maximum absorption wavelength (CHCl ₃ ): 347.0 nm
Molar extinction coefficient (CHCl ₃ ): 40000 (mol / l) ⁻¹ · cm ⁻¹

[Reference example]
In evaluating the photosensitive composition for volume hologram recording, the photosensitive solution of the squarylium compounds of Examples 1 to 7 was evaluated.

[Reference Examples 1-8]
[Evaluation of photosensitive resin solution]
Sample preparation:
100 parts of pentaerythritol triacrylate, 100 parts of polyvinylpyrrolidone, 1 part of the compound and 8 parts of radical generator were dissolved in 900 ml of ethyl cellosolve to obtain a photosensitive resin solution. This photosensitive resin solution was applied to a grained PET film by spin coating so as to have a dry film thickness of 2 μm, and dried at 80 ° C. for 2 minutes.
Sensitivity evaluation:
It exposed in nitrogen stream and evaluated by the minimum hardening light quantity by a gray scale method.
Using a high-pressure mercury lamp (250 W) as a light source, using an L-39 sharp cut filter, V-40 bandpass filter (manufactured by Toshiba Glass), and HA-30 heat ray absorption filter (manufactured by HOYA), taking out the 405 nm emission line of the mercury lamp. did. Development was carried out with methanol for 1 minute, and the sensitivity (minimum curing light amount) was determined from the number of curing stages. The sensitivity is expressed as a specific numerical value by calculating the following equation. The smaller the sensitivity value, the better the sensitivity.
(Sensitivity) = I x t x T (sensitivity unit: mJ / cm ² )
I = light intensity, t = exposure time, T = transmittance with respect to the number of curing steps

TCT：トリクロロメチルトリアジン
BTTB：3,3’,4,4’−テトラキス（ｔ−ブチルジオキシカルボニル）ベンゾフェノン
PBIF：１，３−（t−ブチルジオキシカルボニル）ベンゼン
BI：ビスイミダゾール Table-1

TCT: Trichloromethyltriazine
BTTB: 3,3 ', 4,4'-tetrakis (t-butyldioxycarbonyl) benzophenone
PBIF: 1,3- (t-butyldioxycarbonyl) benzene
BI: Bisimidazole

  Next, a photosensitive medium for volume hologram recording was prepared using the sensitizing dye and radical generator described in Reference Example, and hologram recording / reproduction evaluation was performed.

[Preparation of photosensitive medium for volume hologram recording]
To a mixed solution of 70 parts of pentaerythritol triacrylate, 30 parts of neopentyl glycol diacrylate, and 50 parts of diethyl sebacate, 0.3 part of Compound 1 as a sensitizing dye and 0.5 part of BTTB as a radical generator were added. And completely dissolved using a magnetic stirrer. This is a photosensitive composition for volume hologram recording.
The photosensitive composition for hologram recording prepared by the above method is sandwiched between two glass plates (length 50 mm, width 50 mm, thickness 1.1 mm) through a PET film spacer having a thickness of 25 μm. Spread the solution evenly with the pinching force, and tape around it to prevent air from entering. This was used as a photosensitive medium for volume hologram recording.

[Hologram recording evaluation result]
The volume hologram recording photosensitive medium prepared as described above was subjected to hologram recording / reproduction evaluation using blue laser light (405 nm) using SHOT-500B manufactured by Pulstec Industrial Co., Ltd. When measured under the condition of light intensity of 5 mW, the diffraction efficiency reached 82% at an exposure dose of 250 mJ / cm ² . In addition, when an angle multiplex recording / reproduction test was performed using the same apparatus, it was confirmed that 21 multiplex recording was possible. M / # (M number) at that time was 2.6. Note that the portion of the sample irradiated with the two-beam laser was discolored compared to the portion not irradiated.

In Example 8, the volume hologram was prepared in the same manner as in Example 1 except that the addition amount of Compound 1 was changed from 0.3 part to 0.2 part, and PBIF 0.8 part was used instead of 0.5 part of BTTB. A photosensitive medium for recording was obtained. Using the same apparatus as in Example 1, hologram recording / reproduction evaluation with blue laser light (405 nm) was performed. When measured under the condition of light intensity of 5 mW, the diffraction efficiency reached 61% at an exposure dose of 2,000 mJ / cm ² . Note that the portion of the sample irradiated with the two-beam laser was discolored compared to the portion not irradiated.

In Example 8, the volume hologram was prepared in the same manner as in Example 1 except that the addition amount of Compound 1 was changed from 0.3 part to 0.5 part and TCT 0.8 part was used instead of 0.5 part of BTTB. A photosensitive medium for recording was obtained. Using the same apparatus as in Example 1, hologram recording / reproduction evaluation with blue laser light (405 nm) was performed. When measured under the condition of light intensity of 5 mW, the diffraction efficiency reached 4% at an exposure amount of 5,000 mJ / cm ² . Note that the portion of the sample irradiated with the two-beam laser was discolored compared to the portion not irradiated.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a photosensitive composition for volume hologram recording that is excellent in sensitivity and short in light fading (bleaching characteristics) with respect to a short wavelength light source.

Claims (3)

Formula (I)

(In the formula, R ¹ and R ² are the same or different and each may have an alkyl group which may have a substituent, an alkoxyl group which may have a substituent, or an aralkyl which may have a substituent. Represents a group, a heterocyclic alkyl group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent, or R ¹ and R ² may each form a heterocyclic group together with the adjacent nitrogen atom), and a photosensitive composition for volume hologram recording, comprising a symmetric squarylium compound represented by: a polymerizable monomer, and a radical generator object. R ¹ represents an aryl group which may have a substituent, and R ² represents an alkyl group which may have a substituent or an aralkyl group which may have a substituent, or R 1 ^{2. The} photosensitive composition for volume hologram recording according to claim 1, comprising a symmetric squarylium compound in which ¹ and R ² may form a heterocyclic ring which may have a substituent together with an adjacent nitrogen atom. object. The photosensitive composition for volume hologram recording according to claim 2, wherein the symmetric type squarylium compound has a maximum absorption wavelength in a wavelength region of 330 nm to 450 nm.