JP2007187968A - Composition for holographic recording, producing method therefor, and optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for holographic recording, from which a holographic optical recording medium having superior storage stability of records to heat can be produced, and to provide a method for producing the same and the optical recording medium that uses the composition for the optical recording medium. <P>SOLUTION: The composition for holographic recording contains at least a monomer, expressed by Formula (1), where X represents a radical polymerizable organic group; Y represents an at least divalent organic linking group; Z represents a ring-opening polymerizable organic group; and n and m are each an integer of 1 or more. Preferably, X is anyone among (meth)acryloyloxy group, (meth)acrylamino group, and styryl group, Z is either a oxirane group and an oxetane group, and Y is a divalent or higher organic linking group, containing at least one benzene skeleton. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is capable of recording and reproducing information using a laser beam, and in particular, a holographic recording composition suitable for producing a volume holographic optical recording medium having a thick recording layer, and the holographic recording composition The present invention relates to a method for producing a composition, and an optical recording medium using the holographic recording composition.

  Conventionally, development of a holographic optical recording medium using a holographic principle has been advanced. In such a holographic optical recording medium, when recording information, information light including image information and reference light are superimposed in a recording layer made of a photosensitive composition, and interference fringes formed at that time are recorded on the recording layer. Is done by writing to On the other hand, when the recorded information is reproduced, the reference light is incident on the recording layer at a predetermined angle, whereby the reference light is diffracted by the formed interference fringes, and the information light is reproduced.

  In recent years, volume holography capable of ultra-high density optical recording, particularly digital volume holography, has been developed at a practical level and attracts attention. Volume holography is a method of writing interference fringes in three dimensions by actively utilizing the thickness direction of the optical recording medium. By increasing the thickness, the diffraction efficiency can be increased and the recording capacity can be increased by multiple recording. There is a feature. Digital volume holography is a computer-oriented holographic recording method that uses a recording medium and a recording method similar to those of volume holography, but restricts image information to be recorded to a binarized digital pattern. In such digital volume holography, for example, image information such as an analog picture is once digitized, developed into two-dimensional digital pattern information, and recorded as image information. At the time of reproduction, the digital pattern information is read and decoded so that the original image information is restored and displayed. As a result, even if the S / N ratio (signal-to-noise ratio) is somewhat poor at the time of reproduction, the original information can be faithfully reproduced by performing differential detection, encoding binary data, and performing error correction. It can be reproduced (see Patent Document 1).

  In the volume holographic optical recording medium, it has been proposed to use various matrices and monomers (see Patent Documents 2 and 3). Further, unlike conventional optical recording media that record information in a pit (mark) format such as a CD or DVD, a holographic optical recording medium writes interference fringes in the form of a refractive index image within a certain volume. Due to the volume shrinkage and volume expansion of the recording layer material due to changes in the recording layer, the shape of the refractive index image can easily change, and the signal to be reproduced may not be reproduced correctly. It is a problem. However, in the above prior art, the storage stability against heat of recording is not sufficient, and the present situation is that further improvement and development are desired.

Japanese Patent Laid-Open No. 11-311936 JP-T-2005-502918 Japanese Patent No. 2873126

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention relates to a holographic recording composition capable of producing a holographic optical recording medium having a high storage stability against recording heat, a method for producing the holographic recording composition, and the holographic recording composition. An object of the present invention is to provide an optical recording medium using the object.

Means for solving the problems are as follows. That is,
<1> A holographic recording composition comprising at least a monomer represented by the following structural formula (1).
However, in said structural formula (1), X represents the radically polymerizable organic group. Y represents a divalent or higher valent organic linking group. Z represents an organic group capable of ring-opening polymerization. n and m each represent an integer of 1 or more.
<2> The holographic recording composition according to <1>, wherein X in the structural formula (1) is any one of a (meth) acryloyloxy group, a (meth) acrylamino group, and a styryl group.
<3> The holographic recording composition according to any one of <1> to <2>, wherein Z in the structural formula (1) is either an oxirane group or an oxetane group.
<4> The holographic recording composition according to any one of <1> to <3>, wherein Y in the structural formula (1) is a divalent or higher-valent organic linking group containing at least one benzene skeleton. .
<5> The holographic recording composition according to any one of <1> to <4>, further including a matrix and a photopolymerization initiator.
<6> The holographic recording composition according to <5>, wherein the matrix has an organic group that can be bonded by reacting with any of X and Z of the monomer represented by the structural formula (1).
<7> The holographic recording composition according to <6>, wherein the bondable organic group in the matrix is any one of a radical polymerizable organic group and a cationic polymerizable organic group.
<8> The above <5>, wherein the photopolymerization initiator is composed of a mixture of two or more photopolymerization initiators, and the mixture contains at least one radical polymerization initiator and at least one ring-opening polymerization initiator. To the composition for holographic recording according to any one of <7>.
<9> For holographic recording according to any one of <1> to <8>, wherein the content of the monomer represented by the structural formula (1) in the holographic recording composition is 1 to 50% by mass. It is a composition.
<10> A method for producing the holographic recording composition according to any one of <1> to <9>,
A matrix forming step of forming a matrix;
A recording and fixing step of recording information and fixing the recording by irradiating light to the obtained matrix and the monomer represented by the following structural formula (1) to cause radical polymerization and ring-opening polymerization. A method for producing a holographic recording composition.
However, in said structural formula (1), X represents the radically polymerizable organic group. Y represents a divalent or higher valent organic linking group. Z represents an organic group capable of ring-opening polymerization. n and m each represent an integer of 1 or more.
<11> An optical recording medium comprising a holographic recording layer comprising the holographic recording composition according to any one of <1> to <9>.
<12> The optical recording medium according to <11>, including a lower substrate, a filter layer, a holographic recording layer, and an upper substrate.

  The holographic recording composition of the present invention contains the monomer represented by the structural formula (1), and preferably contains a matrix and a photopolymerization initiator, so that the recorded information is fixed. Thus, an optical recording medium with improved heat storage stability can be produced efficiently.

  According to the present invention, a holographic recording composition capable of solving conventional problems and producing a holographic optical recording medium having high storage stability against recording heat, and a method for producing the holographic recording composition, In addition, an optical recording medium using the composition for optical recording medium can be provided.

(Holographic recording composition)
The holographic recording composition of the present invention contains at least a monomer represented by the following structural formula (1), and further contains a matrix, a photopolymerization initiator, and, if necessary, other components.
However, in said structural formula (1), X represents the radically polymerizable organic group. Y represents a divalent or higher valent organic linking group. Z represents an organic group capable of ring-opening polymerization. n and m each represent an integer of 1 or more.

<Monomer represented by Structural Formula (1)>
In the structural formula (1), examples of the radical polymerizable organic group represented by X include an acryloyloxy group, a methacryloyloxy group, an acryloylamino group, a methacryloylamino group, a styryl group, an α-substituted styryl group, and vinyl. Group, allyl group, maleic acid group, maleic anhydride group, maleic acid amide group and the like. Among these, acryloyloxy group, methacryloyloxy group, acryloylamino group, methacryloylamino group, styryl group, vinyl group and allyl group are preferable, and acryloyloxy group, methacryloyloxy group, acryloylamino group, methacryloylamino group and styryl group are preferable. More preferred is an acryloyloxy group or an acryloylamino group.

In the structural formula (1), examples of the ring-opening polymerizable substituent represented by Z include an oxirane group, an oxiranylmethyloxy group, an oxiranylethyloxyoxy group, and 2,3-epoxypropylcarbonyl. Oxy group, oxetane group, 2-oxetanylmethyloxy group, 3-oxetanylmethyloxy group, 3-oxetanylethyloxy group, propylene carbonate group, 1,3-dioxolan-2-onemethoxy group, butyl carbonate group, γ-butyrolactone Group, γ-butyrolactam group and the like. Among these, an oxirane group, an oxiranylmethyloxy group, an oxiranylethyloxyoxy group, an oxetane group, a propylene carbonate group, a butyl carbonate group, and a γ-butyrolactone group are preferable, and an oxirane group, an oxetane group, and an oxiranylmethyl group. An oxy group and a propylene carbonate group are more preferable, and an oxirane group and an oxetane group are particularly preferable. Specific examples of such substituents capable of ring-opening polymerization are given below.

  In the structural formula (1), n and m each represent an integer of 1 or more. n + m is preferably 2 to 6, more preferably 2 to 4, and particularly preferably 2 to 3.

In the structural formula (1), the divalent or higher valent organic linking group represented by Y is not particularly limited as long as X and Z can be linked, and the structure of the organic linking group includes an ether bond. , An ester bond, an amino bond, an amide bond, a carbamate bond and the like may be contained.
As the divalent or higher valent organic linking group represented by Y, as the divalent organic group, for example, an alkylene group and an arylene group are preferable, and an arylene group is particularly preferable. As the trivalent organic group, for example, an alkanetriyl group and an arenetriyl group are preferable, and an arenetriyl group is particularly preferable. As the tetravalent organic group, for example, an alkanetetrayl group and an arenetetrayl group are preferable, and an arenetetrayl group is particularly preferable.
As the divalent or higher valent organic linking group represented by Y, those containing at least a benzene skeleton are more preferable.

The alkylene group may have a branch or may have a substituent, preferably has 1 to 30 carbon atoms, and more preferably has 1 to 20 carbon atoms. As the substituent, a halogen atom, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and an aryloxycarbonyl group are preferable. Among these, a halogen atom and an aryl group are particularly preferable. Further, the alkylene chain may have a divalent functional group so as not to be adjacent to each other. Examples of such a divalent functional group include -O-, -S-, -COO-, -O. -CO- is preferred, and -O- is particularly preferred. In addition, an arylene group or an alkenylene group may be present in at least one of the alkylene chain and at one end of the alkylene chain, and the arylene group is particularly preferable. Specific examples of such an alkylene group are given below.
However, in said formula, Me represents a methyl group.

The arylene group may have a substituent, preferably has 6 to 30 carbon atoms, and particularly preferably has 6 to 20 carbon atoms. Examples of the substituent include a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, an aryloxy group, an alkylthio group, an alkoxycarbonyl group, and an aryloxycarbonyl group. Among these, a halogen atom, an alkoxy group, and an alkylthio group are particularly preferable. The arylene chain may have divalent functional groups so as not to be adjacent to each other. Examples of such divalent functional groups include -O-, -S-, -COO-, -O. -CO- is preferred, and -O- is particularly preferred. Specific examples of such an arylene group are given below.
However, in said formula, Me represents a methyl group.

The alkanetriyl group may have a branch or may have a substituent, preferably having 1 to 30 carbon atoms, particularly preferably having 1 to 20 carbon atoms. As the substituent, a halogen atom, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and an aryloxycarbonyl group are preferable. Among these, a halogen atom and an aryl group are particularly preferable. The alkanetriyl group may have divalent functional groups so as not to be adjacent to each other. Examples of such divalent functional groups include —O—, —S—, and —COO—. , -O-CO- is preferable, and -O- is particularly preferable. In addition, an arylene group or an alkenylene group may be present in at least one of the alkanetriyl group and at one end of the alkanetriyl group, and the arylene group is particularly preferable. Examples of such alkanetriyl groups are given below.

The arenetriyl group may have a substituent, preferably has 6 to 30 carbon atoms, and particularly preferably has 6 to 20 carbon atoms. Examples of the substituent include a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, an aryloxy group, an alkylthio group, an alkoxycarbonyl group, and an aryloxycarbonyl group. Among these, a halogen atom, an alkoxy group, and an alkylthio group are exemplified. Particularly preferred. Further, the arenetriyl group may have a divalent functional group so as not to be adjacent to each other. Examples of such a divalent functional group include —O—, —S—, and —COO—. , -O-CO- is preferable, and -O- is particularly preferable. Specific examples of such arenetriyl groups are given below.

The alkanetetrayl group may have a branch or may have a substituent, preferably having 1 to 30 carbon atoms, particularly preferably having 1 to 20 carbon atoms. Examples of the substituent include a halogen atom, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, and an aryloxycarbonyl group. Among these, a halogen atom and an aryl group are particularly preferable. The alkanetetrayl group may have divalent functional groups so as not to be adjacent to each other. Examples of such divalent functional groups include -O-, -S-, and -COO-. , -O-CO- is preferable, and -O- is particularly preferable. In addition, an arylene group or an alkenylene group may be present in at least one of the alkanetetrayl group and at one end of the alkanetetrayl group, and the arylene group is particularly preferable. Specific examples of such alkanetetrayl groups are given below.
However, in said formula, Me represents a methyl group.

The arenetetrayl group may have a substituent, preferably has 6 to 30 carbon atoms, and particularly preferably has 6 to 20 carbon atoms. Examples of the substituent include a halogen atom, an alkyl group, an alkenyl group, an alkoxy group, an aryloxy group, an alkylthio group, an alkoxycarbonyl group, and an aryloxycarbonyl group. Among these, a halogen atom, an alkoxy group, an alkylthio group Is particularly preferred. The arenetetrayl group may have divalent functional groups so as not to be adjacent to each other. Examples of such divalent functional groups include -O-, -S-, and -COO-. , -O-CO- is preferable, and -O- is particularly preferable. Specific examples of such arenetetrayl groups are given below.
However, in said formula, Me represents a methyl group.

Specific examples of the monomer represented by the structural formula (1) are shown below, but are not limited thereto. These monomers may be used individually by 1 type, and may use 2 or more types together.
However, in said formula, Me represents a methyl group.

—Method for Synthesizing Monomer Represented by Structural Formula (1) —
As shown in the following reaction formula, the compound represented by M-1 as the monomer represented by the structural formula (1) is converted to p-aminophenol (manufactured by Tokyo Chemical Industry Co., Ltd.) with N, N-dimethylacetamide ( Acroyl chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) is allowed to act using Tokyo Chemical Industry Co., Ltd. The compound can be synthesized by allowing epichlorohydrin (manufactured by Tokyo Chemical Industry Co., Ltd.) to act in a water-ethanol mixed solvent of sodium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.).

  The monomer represented by the structural formula (1) may be used in combination with other monomers as necessary. Examples of the other monomer include a radical polymerization type monomer having an unsaturated bond such as an acrylic group and a methacryl group, and a ring-opening polymerization type monomer such as an epoxy compound and an oxetane compound. These other monomers may be monofunctional or polyfunctional.

  Examples of the radical polymerization type monomer include acryloylmorpholine, phenoxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, 2-ethylhexyl acrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, neo Pentyl glycol PO modified diacrylate, 1,9-nonanediol diacrylate, hydroxypivalate neopentyl glycol diacrylate, EO modified bisphenol A diacrylate, polyethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol hexa Acrylate, EO-modified glycerol triacrylate, trimethylol group Pantriacrylate, EO-modified trimethylolpropane triacrylate, 2-naphth-1-oxyethyl acrylate, 2-carbazoyl-9-ylethyl acrylate, (trimethylsilyloxy) dimethylsilylpropyl acrylate, vinyl-1-naphthoate, N-vinyl Examples thereof include carbazole, 2,4,6-tribromophenyl acrylate, pentabromo acrylate, phenylthioethyl acrylate, tetrahydrofurfuryl acrylate, and the like.

  Examples of the ring-opening polymerization type monomer include 2,3-epoxy-1-propane, 3,4-epoxy-1-butane, 1,6-hexanediol monoglycidyl ether, glycerol diglycidyl ether, and glycerol propoxylate. Diglycidyl ether, glycerol propoxylate diglycidyl ether, glycidyl 4-hydroxyphenyl ether, glycidyl phenyl ether, 1,2-epoxyethylbenzene, bisphenol A diglycidyl ether, pentaerythritol tetra (3-ethyl-3-oxetanylmethyl) ether, Examples include 3-ethylene carbonate, propylene carbonate, and γ-butyrolactone.

  The content of the monomer in the holographic recording composition is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferably 1 to 50% by mass, more preferably 1 to 30% by mass, and 3 More preferably, it is 10 mass%. If the content exceeds 50% by mass, a stable interference image may not be obtained, and if it is less than 1% by mass, desirable performance may not be obtained in terms of diffraction efficiency.

-Analysis method of monomer represented by structural formula (1)-
As a method for analyzing the monomer represented by the structural formula (1), the recording layer portion of an optical recording medium (for example, Example 1 described later) having a recording layer made of the holographic recording composition of the present invention is used as tetrahydrofuran. It is possible to extract with (THF) or dioxane and analyze by gas chromatography (GC).

<Matrix>
The matrix is a polymer for holding a monomer and a photopolymerization initiator related to recording and storage.
There is no restriction | limiting in particular as said matrix, Although it can select suitably according to the objective, It can also form by casting with a solvent. Moreover, as what is formed by reaction, a photocurable matrix, an acid (base) curable matrix, a thermosetting matrix, etc. are mentioned. Among these, the thermosetting matrix is suitable for producing an optical recording medium.

  Examples of the matrix include a polyurethane compound formed from an isocyanate compound and an alcohol compound, a polyether compound formed from an oxirane compound and an oxetane compound, a polyester compound formed from an alcohol compound and an alcohol, and (meth) acrylic. Examples thereof include polyolefin compounds obtained by polymerizing an ester compound of an unsaturated acid such as an acid and an amide compound.

It is preferable that the matrix has an organic group that can be bonded by reacting with any of X and Z of the monomer represented by the structural formula (1).
The reaction means forming a covalent bond, and a polymerization reaction, an addition reaction, and a substitution reaction are preferable, and a polymerization reaction and an addition reaction are more preferable. For example, radical polymerization reactions of ester compounds and amide compounds of unsaturated acids such as (meth) acrylic acid, ring-opening polymerization reactions of epoxy compounds and oxetane compounds, addition reactions of carboxylic acids to epoxy compounds, addition reactions of acid anhydrides And addition reaction of an amine compound, addition reaction of a hydroxyl group, and the like.
Examples of such bondable organic groups include, for example, radical-polymerizable organic groups capable of bonding to X, such as acryloyloxy group, methacryloyloxy group, acryloylamino group, methacryloylamino group, styryl group, and α-substituted. Examples thereof include a styryl group, a vinyl group, an allyl group, a maleic acid group, a maleic anhydride group, and a maleic acid amide group. Among these, acryloyloxy group, methacryloyloxy group, acryloylamino group, methacryloylamino group, styryl group, vinyl group and allyl group are particularly preferable.
Examples of the cationically polymerizable organic group that can be bonded to Z include oxirane group, oxetane group, propylene carbonate group, butyl carbonate group, γ-butyrolactone group, γ-butyrolactam group, carboxylic acid group, acid anhydride, hydroxyl group, and the like. Can be mentioned. Among these, an oxirane group and an oxetane group are particularly preferable.

  The method for forming a matrix having an organic group capable of binding by reacting with any of the above X and Z is not particularly limited and can be appropriately selected according to the purpose. For example, when the matrix is a polyurethane compound, By adding a radically polymerizable compound having a hydroxyl group, an acid anhydride, an amino group or an isocyanate group to the alcohol compound and the isocyanate compound, or a compound capable of ring-opening polymerization having a hydroxyl group, an acid anhydride or an isocyanate group, the above-mentioned A matrix can be obtained. When the matrix is a polyether compound, the above matrix can be obtained by ring-opening polymerization in the state where an oxirane compound having a radical polymerizable group is coexisted with the oxirane compound. Further, in the case of a polyolefin compound, a polymer compound of an ester compound of an unsaturated acid containing a polymerizable group is obtained by stopping the polymerization while leaving a part of the polymerizable site using a polyfunctional monomer. In addition, a polyolefin compound having an oxirane moiety can be formed by forming a copolymer of an ester compound of an unsaturated acid capable of ring-opening polymerization such as oxirane.

  The content of the matrix in the holographic recording composition is preferably 10 to 95% by mass, and more preferably 35 to 90% by mass. When the content is less than 10% by mass, a stable interference image may not be obtained, and when it exceeds 95% by mass, desirable performance may not be obtained in terms of diffraction efficiency.

<Photopolymerization initiator>
The photopolymerization initiator is not particularly limited as long as it can be a starting species that causes a chemical reaction by light, and can be appropriately selected according to the purpose, and includes a radical polymerization initiator and a ring-opening polymerization initiator. It is preferable to include either or both. In this case, the photopolymerization initiator is composed of a mixture of two or more photopolymerizable initiators, and the mixture contains at least one radical polymerization initiator and at least one ring-opening polymerization initiator. Is more preferable.

The radical polymerization initiator is not particularly limited as long as it has sensitivity to recording light, and examples thereof include materials that cause radical polymerization by light irradiation.
Examples of the radical polymerization initiator include 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,1′-biimidazole, 2,4,6-tris. (Trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenylvinyl) -1,3,5-triazine, diphenyliodonium tetrafluoroborate, diphenyliodonium hexa Fluorophosphate, 4,4′-di-t-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, benzoin, 2-hydroxy-2-methyl-1-phenylpropan-2-one, benzophenone, Thioxanthone, 2,4,6-trimethylbenzoy Diphenylacylphosphine oxide, triphenylbutyl borate tetraethylammonium, bis (η-5-2,4-cyclopentadien-1-yl), bis [2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl Titanium], diphenyl-4-phenylthiophenylsulfonium hexafluorophosphate, and the like. These may be used individually by 1 type and may use 2 or more types together. In addition, you may use together the sensitizing dye mentioned later according to the wavelength of the light to irradiate.

  Examples of the ring-opening polymerization initiator include 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (p-methoxyphenylvinyl). -1,3,5-triazine, diphenyliodonium tetrafluoroborate, 4,4′-di-t-butyldiphenyliodonium tetrafluoroborate, 4-diethylaminophenylbenzenediazonium hexafluorophosphate, diphenyl-4-phenylthiophenylsulfonium hexa A fluorophosphate etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. In addition, you may use together the sensitizing dye mentioned later according to the wavelength of the light to irradiate.

  The content of the photopolymerization initiator in the holographic recording composition is preferably 0.01 to 5% by mass, and more preferably 1 to 3% by mass.

A sensitizing dye may be added to the holographic recording composition as necessary. Examples of the sensitizing dye include “Research Disclosure, Vol. 200, December 1980, Item 20036” and “sensitizer” (p.160 to p.163, Kodansha; Katsumi Tokumaru and Nobu Okawara, edited by 1987. ) And the like can be used.
Specific examples of the sensitizing dye include a 3-ketocoumarin compound described in JP-A-58-15603, a thiopyrylium salt described in JP-A-58-40302, and JP-B-59-28328. The naphthothiazole merocyanine compound described in JP-A-60-53300, the merocyanine compound described in JP-B-61-9621, JP-A-62-2842, JP-A-59-89303, and JP-A-60-60104 Can be mentioned.
Further, the dyes described in “Functional dye chemistry” (1981, CMC Publishing Co., p.393 to p.416), “Coloring materials” (60 [4] 212-224 (1987)), and the like are also included. be able to. Specific examples include a cationic methine dye, a cationic carbonium dye, a cationic quinoneimine dye, a cationic indoline dye, and a cationic styryl dye.
In addition, coumarin (including ketocoumarin or sulfonocoumarin) dyes, melostyryl dyes, oxonol dyes, hemioxonol dyes, and other keto dyes; non-ketopolymethine dyes, triarylmethane dyes, xanthene dyes, anthracene dyes, rhodamine dyes, acridine dyes Non-keto dyes such as aniline dyes and azo dyes; Non-ketopolymethine dyes such as azomethine dyes, cyanine dyes, carbocyanine dyes, dicarbocyanine dyes, tricarbocyanine dyes, hemicyanine dyes, styryl dyes; azine dyes, oxazine dyes, thiazines And quinone imine dyes such as dyes, quinoline dyes, and thiazole dyes.
The said sensitizing dye may be used individually by 1 type, and may be used in combination of 2 or more type.

As the other components, a polymerization inhibitor or an antioxidant may be added for the purpose of improving the storage stability of the holographic recording composition.
Examples of the polymerization inhibitor or the antioxidant include hydroquinone, p-benzoquinone, hydroquinone monomethyl ether, 2,6-ditertiary butyl-p-cresol, 2,2′-methylenebis (4-methyl-6-tertiary- Butylphenol), trifel phosphite, trisnonylphenyl phosphite, phenothiazine, N-isopropyl-N′-phenyl-p-phenylenediamine and the like.
The addition amount of the polymerization inhibitor or antioxidant is preferably 3% by mass or less based on the total amount of the recording monomer. When the addition amount exceeds 3% by mass, the polymerization may be slowed or may not be polymerized when it is remarkable.

The holographic recording composition can also contain a photothermal conversion material for the purpose of improving the sensitivity of the recording layer comprising the holographic recording composition.
The photothermal conversion material is not particularly limited and can be appropriately selected depending on the intended function and performance. For example, it can be easily added to the recording layer together with a photopolymer, or can cause scattering of incident light. Organic dyes are preferred from the standpoint of the absence of properties, and infrared absorbing dyes are preferred in that they do not absorb or scatter light from the light source used for recording.
The infrared absorbing dye is not particularly limited and may be appropriately selected depending on the intended purpose. Cationic dyes, complex salt-forming dyes, quinone neutral dyes, and the like are preferable. Further, the maximum absorption wavelength of the infrared absorbing dye is preferably in the range of 600 to 1,000 nm, and more preferably in the range of 700 to 900 nm.
The content of the infrared absorbing dye is determined by the absorbance of the wavelength having the highest absorbance in the infrared region in the produced recording material. As this light absorbency, the range of 0.1-2.5 is preferable, and the range of 0.2-2.0 is more preferable.
The holographic recording composition may further contain a component that diffuses in a direction opposite to the polymerization component, or an acid-cleavage structure, if necessary, in order to alleviate the volume change during polymerization. In addition to the polymer, a compound having the above may be added separately.

(Method for producing holographic recording composition)
The method for producing a composition for holographic recording of the present invention comprises a matrix forming step for forming a matrix, and radical polymerization and ring-opening polymerization by irradiating the matrix and the monomer represented by the structural formula (1) with light. Thus, it includes a recording and fixing step for recording information and fixing the recording, and further includes other steps as necessary.

In the formation process of the matrix, each compound may be added at once or sequentially, but it is preferable to add at a time from the simplicity of the production method.
In the recording and fixing step, the holographic recording composition undergoes two steps as an information recording and fixing method. One is information recording, and the other is recording fixing. Fixing here means polymerizing the monomer represented by the conceptual formula (1), or bonding a polymer formed upon recording to the matrix. This prevents further information from being recorded and improves the storability of the recorded information. For example, information can be recorded by radical polymerization that generates radicals with long wave light, and can be fixed by ring-opening polymerization with short wave light. Or, conversely, information can be recorded by ring-opening polymerization using long wave light and fixed by radical polymerization using short wave light.

The holographic recording composition of the present invention can be used for various holographic recording compositions capable of recording information by irradiation with light containing information. preferable.
If the holographic recording composition has a sufficiently low viscosity, the recording layer can be formed by casting. On the other hand, if the viscosity is so high that casting cannot be performed, a recording layer is placed on the lower substrate using a dispenser, and the recording layer is pressed to cover the upper substrate and spread over the entire surface. Can be formed.

(Optical recording medium)
The optical recording medium of the present invention has a holographic recording layer comprising the holographic recording composition of the present invention, and preferably has a lower substrate, a filter layer, a holographic recording layer, and an upper substrate. Thus, it has a reflective film, a first gap layer, a second gap layer, and other layers as required.
The optical recording medium is not particularly limited as long as it can be recorded and reproduced using the principle of hologram, and records a large amount of information such as a relatively thin planar hologram or a three-dimensional image for recording information such as two dimensions. It may be a volume hologram, and may be either a transmission type or a reflection type. The hologram recording method may be any, for example, an amplitude hologram, a phase hologram, a blazed hologram, a complex amplitude hologram, or the like. Among these, information recording in the volume holographic recording area is performed by irradiating the volume holographic recording area with information light and reference light as a coaxial light beam, and recording information by an interference pattern due to interference between the information light and the reference light. The so-called collinear method is particularly preferable.

-Board-
The shape, structure, size and the like of the substrate are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a disk shape and a card shape. It is necessary to select a material that can ensure the mechanical strength of the medium. In addition, when light used for recording and reproduction enters through the substrate, it is necessary to be sufficiently transparent in the wavelength region of the light used.
As the substrate material, glass, ceramics, resin, and the like are usually used, but resin is particularly preferable from the viewpoint of moldability and cost.
Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, and urethane resin. Among these, polycarbonate resin and acrylic resin are particularly preferable from the viewpoints of moldability, optical characteristics, and cost.
The substrate may be appropriately synthesized or a commercially available product may be used.
The substrate is provided with address-servo areas as a plurality of positioning regions extending linearly in the radial direction at predetermined angular intervals, and a sector-shaped section between adjacent address-servo areas is a data area. In the address-servo area, information for performing focus servo and tracking servo by the sampled servo method and address information are recorded in advance by embossed pits (servo pits) (preformat). Note that the focus servo can be performed using the reflective surface of the reflective film. As information for performing the tracking servo, for example, a wobble pit can be used. If the optical recording medium has a card shape, the servo pit pattern may be omitted.
There is no restriction | limiting in particular as thickness of the said board | substrate, According to the objective, it can select suitably, 0.1-5 mm is preferable and 0.3-2 mm is more preferable. If the thickness of the substrate is less than 0.1 mm, the distortion of the shape during storage of the disc may not be suppressed. If the thickness exceeds 5 mm, the mass of the entire disc increases and an excessive load is applied to the drive motor. Sometimes.

-Recording layer-
The recording layer can record information using holography, and is composed of the holographic recording composition of the present invention.
There is no restriction | limiting in particular as thickness of the said recording layer, According to the objective, it can select suitably, 1-1000 micrometers is preferable and 100-700 micrometers is more preferable.
When the thickness of the recording layer is within the preferable numerical range, a sufficient S / N ratio can be obtained even when 10 to 300 multiple shift multiplexing is performed, and when the thickness is within the more preferable numerical range, this is remarkable. It is advantageous in some respects.

-Reflective film-
The reflective film is formed on the surface of the servo pit pattern of the substrate.
As the material of the reflective film, a material having a high reflectance with respect to recording light or reference light is preferably used. When the wavelength of light to be used is 400 to 780 nm, for example, Al, Al alloy, Ag, Ag alloy, etc. are preferably used. When the wavelength of light to be used is 650 nm or more, it is preferable to use Al, Al alloy, Ag, Ag alloy, Au, Cu alloy, TiN, or the like.
As the reflective film, an optical recording medium that reflects light and can be written or erased, such as a DVD (digital video disk), is used. It is also possible to add and rewrite directory information such as information on which part has an error and how replacement processing is performed without affecting the hologram.
The formation of the reflective film is not particularly limited and can be appropriately selected according to the purpose. Various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating An electron beam evaporation method or the like is used. Among these, the sputtering method is excellent in terms of mass productivity and film quality.
The thickness of the reflective film is preferably 50 nm or more, and more preferably 100 nm or more so that sufficient reflectance can be realized.

-First gap layer-
The first gap layer is provided between the filter layer and the reflective film as necessary, and is formed for the purpose of smoothing the lower substrate surface. It is also effective for adjusting the size of the hologram generated in the recording layer. That is, since it is necessary for the recording layer to form an interference region for recording reference light and information light to a certain size, it is effective to provide a gap between the recording layer and the servo pit pattern.
The first gap layer can be formed, for example, by applying a material such as an ultraviolet curable resin on the servo pit pattern by spin coating or the like and curing it. Moreover, when using what apply | coated and formed on the transparent base material as a filter layer, this transparent base material will work | function also as a 1st gap layer.
There is no restriction | limiting in particular as thickness of the said 1st gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.

-Filter layer-
The filter layer is provided on the servo pits of the substrate, the reflective layer, or the first gap layer.
The filter layer has a wavelength selective reflection function that reflects only light of a specific wavelength from among a plurality of types of light, transmits the first light, and reflects the second light. In particular, the selective reflection wavelength does not shift even when the incident angle changes, and the function of preventing irregular reflection from the reflection film of the optical recording medium by the information light and the reference light, and also preventing the occurrence of noise. By laminating the filter layer on the recording medium, optical recording with high resolution and excellent diffraction efficiency can be obtained.
The filter layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a dichroic mirror layer, a color material-containing layer, a dielectric vapor deposition layer, a single layer or two or more cholesteric layers and necessary It is formed by a laminate in which at least one of other layers appropriately selected according to the above is laminated.
The filter layer may be laminated together with the direct recording layer on the substrate by coating or the like, or may be laminated on a substrate such as a film to produce a filter layer, which may be laminated on the substrate. .

-Second gap layer-
The second gap layer is provided between the recording layer and the filter layer as necessary.
The material of the second gap layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, triacetyl cellulose (TAC), polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS) ), Transparent resin films such as polysulfone (PSF), polyvinyl alcohol (PVA), polymethyl methacrylate = polymethyl methacrylate (PMMA), etc. And norbornene-based resin films. Among these, those having high isotropic properties are preferred, and TAC, PC, trade name ARTON, and trade name ZEONOR are particularly preferred.
There is no restriction | limiting in particular as thickness of the said 2nd gap layer, According to the objective, it can select suitably, 1-200 micrometers is preferable.

Here, the optical recording medium of the present invention will be described in more detail with reference to the drawings.
<First embodiment>
FIG. 1 is a schematic cross-sectional view showing the configuration of the optical recording medium in the first embodiment of the present invention. In the optical recording medium 21 according to the first embodiment, a servo pit pattern 3 is formed on a polycarbonate resin substrate or a glass substrate 1, and the servo pit pattern 3 is coated with aluminum, gold, platinum or the like to be a reflective film 2 is provided. In FIG. 1, the servo pit pattern 3 is formed on the entire surface of the lower substrate 1, but it may be formed periodically. The height of the servo pit pattern 3 is usually 1750 mm (175 nm), which is sufficiently smaller than the thicknesses of the substrate and other layers.
The first gap layer 8 is formed by applying a material such as an ultraviolet curable resin on the reflective film 2 of the lower substrate 1 by spin coating or the like. The first gap layer 8 is effective for protecting the reflective film 2 and adjusting the size of the hologram generated in the recording layer 4. That is, since it is necessary to form an interference area between the recording reference light and the information light in a certain size in the recording layer 4, it is effective to provide a gap between the recording layer 4 and the servo pit pattern 3.
A filter layer 6 is provided on the first gap layer 8, and an optical recording medium 21 is configured by sandwiching the recording layer 4 between the filter layer 6 and the upper substrate 5 (a polycarbonate resin substrate or a glass substrate).
In FIG. 1, the filter layer 6 transmits only red light and does not transmit light of other colors. Therefore, since the information light, the recording and reproduction reference light are green or blue light, the light does not pass through the filter layer 6 and does not reach the reflection film 2 and becomes return light, which is emitted from the incident / exit surface A. Become.
The filter layer 6 is a multilayer deposited film in which high refractive index layers and low refractive index layers are alternately stacked.
The filter layer 6 composed of the multilayer deposited film may be directly formed on the first gap layer 8 by vacuum deposition, or a film having the multilayer deposited film formed on the substrate is punched into an optical recording medium shape and arranged. May be.
The optical recording medium 21 in the present embodiment may be disk-shaped or card-shaped. In the case of a card shape, there is no need for the servo pit pattern. In this optical recording medium 21, the lower substrate 1 is 0.6 mm, the first gap layer 8 is 100 μm, the filter layer 6 is 2 to 3 μm, the recording layer 4 is 0.6 mm, and the upper substrate 5 is 0.6 mm. The total thickness is about 1.9 mm.

Next, the optical operation around the optical recording medium 21 will be described with reference to FIG. First, light (red light) emitted from the servo laser is reflected almost 100% by the dichroic mirror 13 and passes through the objective lens 12. Servo light is applied to the optical recording medium 21 by the objective lens 12 so as to be focused on the reflective film 2. That is, the dichroic mirror 13 transmits light having a wavelength of green or blue, and reflects light having a wavelength of red by almost 100%. The servo light incident from the light incident / exiting surface A of the optical recording medium 21 passes through the upper substrate 5, the recording layer 4, the filter layer 6, and the first gap layer 8, is reflected by the reflective film 2, and again, The light passes through the first gap layer 8, the filter layer 6, the recording layer 4, and the upper substrate 5 and is emitted from the incident / exit surface A. The returned return light passes through the objective lens 12, is reflected almost 100% by the dichroic mirror 13, and servo information is detected by a servo information detector (not shown). The detected servo information is used for focus servo, tracking servo, slide servo, and the like. Since the hologram material constituting the recording layer 4 is not sensitive to red light, even if the servo light passes through the recording layer 4 or the servo light is irregularly reflected by the reflective film 2, the recording layer 4 is not affected. In addition, since the return light of the servo light reflected by the reflective film 2 is reflected almost 100% by the dichroic mirror 13, the servo light is detected by the CMOS sensor or the CCD 14 for detecting the reproduced image. In addition, there is no noise with respect to the reproduction light.
The information light and the recording reference light generated from the recording / reproducing laser pass through the polarizing plate 16 to become linearly polarized light, pass through the half mirror 17 and pass through the quarter-wave plate 15. It becomes circularly polarized light. The optical recording medium 21 is irradiated with information light and recording reference light through the dichroic mirror 13 so as to generate an interference pattern in the recording layer 4 by the objective lens 12. The information light and the recording reference light are incident from the incident / exit surface A and interfere with each other in the recording layer 4 to generate an interference pattern there. Thereafter, the information light and the recording reference light pass through the recording layer 4 and enter the filter layer 6, but are reflected to the bottom surface of the filter layer 6 to become return light. That is, the information light and the recording reference light do not reach the reflective film 2. This is because the filter layer 6 is a multilayer deposited layer in which a plurality of high refractive index layers and low refractive index layers are alternately stacked, and has a property of transmitting only red light.

<Second Embodiment>
FIG. 2 is a schematic cross-sectional view showing the configuration of the optical recording medium in the second embodiment of the present invention. In the optical recording medium 22 according to the second embodiment, a servo pit pattern 3 is formed on a polycarbonate resin or glass substrate 1, and the surface of the servo pit pattern 3 is coated with aluminum, gold, platinum or the like to form a reflective film 2. Is provided. The height of the servo pit pattern 3 is the same as that of the first embodiment in that it is normally 1750 mm (175 nm).
The difference in structure between the second embodiment and the first embodiment is that the second gap layer 7 is provided between the filter layer 6 and the recording layer 4 in the optical recording medium 22 according to the second embodiment. It is that you are. The second gap layer 7 has a point where information light and reproduction light are focused. If this area is filled with a photopolymer, excessive consumption of monomers due to overexposure occurs, resulting in a decrease in multiple recording capability. Therefore, it is effective to provide a non-reactive and transparent second gap layer.
A filter layer 6, which is a multilayer deposited film in which a plurality of high refractive index layers and low refractive index layers are alternately stacked, is formed on the first gap layer 8 after the first gap layer 8 is formed. The thing similar to embodiment can be used.
In the optical recording medium 22 of the second embodiment, the lower substrate 1 is 1.0 mm, the first gap layer 8 is 100 μm, the filter layer 6 is 3 to 5 μm, the second gap layer 7 is 70 μm, and the recording layer 4 is The thickness of the upper substrate 5 is 0.6 mm, and the total thickness is about 2.2 mm.

  Next, when recording or reproducing information, red servo light, green information light, and recording and reproduction reference light are applied to the optical recording medium 22 of the second embodiment having the above-described structure. Irradiated. The servo light enters from the incident / exit surface A, passes through the recording layer 4, the second gap layer 7, the filter layer 6, and the first gap layer 8 and is reflected by the reflective film 2 to become return light. The return light again passes through the first gap layer 8, the filter layer 6, the second gap layer 7, the recording layer 4, and the upper substrate 5 in this order, and exits from the incident / exit surface A. The emitted return light is used for focus servo, tracking servo, and the like. Since the hologram material constituting the recording layer 4 is not sensitive to red light, even if the servo light passes through the recording layer 4 or the servo light is irregularly reflected by the reflective film 2, the recording layer 4 is not affected. Green information light or the like enters from the incident / exit surface A, passes through the recording layer 4 and the second gap layer 7, is reflected by the filter layer 6, and becomes return light. The return light again passes through the second gap layer 7, the recording layer 4, and the upper substrate 5 in this order, and is emitted from the incident / exit surface A. Also during reproduction, not only the reproduction reference light but also the reproduction light generated by irradiating the reproduction reference light onto the recording layer 4 is emitted from the incident / exit surface A without reaching the reflection film 2. The optical operation in the vicinity of the optical recording medium 22 (the objective lens 12, the filter layer 6, the CMOS sensor or the CCD 14 as a detector in FIG. 3) is the same as in the first embodiment, and a description thereof will be omitted.

(Recording method of optical recording medium and reproducing method of optical recording medium)
The optical recording medium recording method of the present invention irradiates the optical recording medium of the present invention with coherent information light and reference light, forms an interference image with the information light and the reference light, An image is recorded on the recording layer of the optical recording medium.
In this case, the information light and the reference light are irradiated to the optical recording medium so that the optical axis of the information light and the optical axis of the reference light are coaxial, and the information light is generated by interference between the information light and the reference light. The interference image is recorded on the recording layer of the optical recording medium.
In the optical recording medium reproducing method of the present invention, information is reproduced by irradiating the interference pattern recorded on the recording layer with the reference light by the optical recording medium recording method of the present invention.

In the optical recording medium recording method and optical recording medium reproducing method of the present invention, as described above, the information light provided with a two-dimensional intensity distribution and the reference light having a substantially constant intensity are used. Information is recorded by superimposing within the photosensitive recording layer and generating a distribution of optical characteristics within the recording layer using an interference pattern formed by them. On the other hand, when reading (reproducing) written information, the recording layer is irradiated with only the reference light in the same arrangement as during recording, and the reproduction has an intensity distribution corresponding to the optical characteristic distribution formed inside the recording layer. Light is emitted from the recording layer as light.
The recording method and reproducing method of the optical recording medium of the present invention are preferably performed using the optical recording / reproducing apparatus of the present invention described below.

An optical recording / reproducing apparatus used in the recording method and reproducing method of the optical recording medium of the present invention will be described with reference to FIG.
The optical recording / reproducing apparatus 100 controls a spindle 81 to which the optical recording medium 20 is attached, a spindle motor 82 for rotating the spindle 81, and the spindle motor 82 so as to keep the rotational speed of the optical recording medium 20 at a predetermined value. A spindle servo circuit 83.
The optical recording / reproducing apparatus 100 records information by irradiating the optical recording medium 20 with information light and recording reference light, and irradiates the optical recording medium 20 with reproduction reference light for reproduction. A pickup 31 for detecting light and reproducing information recorded on the optical recording medium 20 and a drive device 84 that can move the pickup 31 in the radial direction of the optical recording medium 20 are provided.
The optical recording / reproducing apparatus 100 uses a detection circuit 85 for detecting a focus error signal FE, a tracking error signal TE, and a reproduction signal RF from an output signal of the pickup 31, and a focus error signal FE detected by the detection circuit 85. Based on this, the actuator in the pickup 31 is driven to move the objective lens (not shown) in the thickness direction of the optical recording medium 20 to perform focus servo, and the tracking error signal detected by the detection circuit 85. Based on TE, a tracking servo circuit 87 that drives an actuator in the pickup 31 to move the objective lens in the radial direction of the optical recording medium 20 to perform tracking servo, a tracking error signal TE, and a command from a controller to be described later. Drive 84 controlled by a and a slide servo circuit 88 for performing a slide servo for moving the pickup 31 in the radial direction of the optical recording medium 20.

  The optical recording / reproducing apparatus 100 further decodes output data of a later-described CMOS or CCD array in the pickup 31 to reproduce data recorded in the data area of the optical recording medium 20 or reproduce from the detection circuit 85. A signal processing circuit 89 that reproduces a basic clock and discriminates an address from the signal RF, a controller 90 that controls the entire optical recording / reproducing apparatus 100, and an operation unit 91 that gives various instructions to the controller 90; It has. The controller 90 inputs the basic clock and address information output from the signal processing circuit 89, and controls the pickup 31, spindle servo circuit 83, slide servo circuit 88, and the like. The spindle servo circuit 83 receives the basic clock output from the signal processing circuit 89. The controller 90 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and the CPU executes a program stored in the ROM using the RAM as a work area. The function of the controller 90 is realized.

  Since the optical recording / reproducing apparatus used in the recording method and reproducing method of the optical recording medium of the present invention uses the optical recording medium of the present invention, the optical recording medium is excellent in storage stability against heat of recording and realizes high-density recording. be able to.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
-Preparation of composition for holographic recording-
31.5 g of biscyclohexylmethane diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), 61.2 g of polypropylene oxide triol (molecular weight 1,000), 2.5 g of 2,3-epoxy-1-propanol (manufactured by Wako Pure Chemical Industries, Ltd.), the following 3.1 g of monomer (M-1) represented by the structural formula, 0.69 g of radical polymerization initiator (manufactured by Ciba Special Chemical Co., Ltd., Irgacure 784), 1.01 g of dibutyl dilaurate tin (manufactured by Wako Pure Chemical Industries, Ltd.), Then, 0.43 g of a ring-opening polymerization initiator (manufactured by Ciba Special Chemical Co., Ltd., Irgacure 250, 75 mass% propyl carbonate solution) was mixed under a nitrogen stream to prepare a holographic recording composition.

(Example 2)
-Preparation of composition for holographic recording-
In Example 1, a holographic recording composition was prepared in the same manner as in Example 1 except that the monomer (M-2) represented by the following structural formula was used instead of the monomer (M-1). .

(Example 3)
-Preparation of composition for holographic recording-
In Example 1, a holographic recording composition was prepared in the same manner as in Example 1 except that the monomer (M-18) represented by the following structural formula was used instead of the monomer (M-1). .

Example 4
-Preparation of composition for holographic recording-
In Example 1, a holographic recording composition was prepared in the same manner as in Example 1 except that the monomer (M-15) represented by the following structural formula was used instead of the monomer (M-1). .

(Example 5)
-Preparation of composition for holographic recording-
In Example 1, a holographic recording composition was prepared in the same manner as in Example 1 except that the monomer (M-4) represented by the following structural formula was used instead of the monomer (M-1). .

(Comparative Example 1)
-Preparation of composition for holographic recording-
2. 31.5 g of biscyclohexylmethane diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.), 61.2 g of polypropylene oxide triol (molecular weight 1,000), 2.5 g of tetramethylene glycol, 2,4,6-tribromophenyl acrylate as a monomer 1 g, 0.69 g of photopolymerization initiator (manufactured by Ciba Special Chemical Co., Ltd., Irgacure 784) and 1.01 g of dibutyl dilaurate tin (manufactured by Wako Pure Chemical Industries, Ltd.) are mixed under a nitrogen stream to produce a composition for holographic recording. A product was prepared.

(Examples 6 to 10 and Comparative Example 2)
-Production of optical recording media-
An antireflection treatment was performed on one surface of 0.5 mm thick glass so that the reflectance by incident light perpendicular to the wavelength of 532 nm was 0.1%, and a first substrate was produced.
An aluminum deposition process was performed on one surface of 0.5 mm thick glass so that the reflectance by incident light perpendicular to the wavelength of 532 nm was 90%, and a second substrate was produced.
Next, a transparent polyethylene terephthalate sheet having a thickness of 500 μm was provided as a spacer on the surface of the first substrate not subjected to the antireflection treatment.
Next, each of the holographic recording compositions of Examples 1 to 5 and Comparative Example 1 is placed on the first substrate, and the aluminum-deposited surface of the second substrate is not entrained on the holographic recording composition. The first substrate and the second substrate were bonded through a spacer. Thereafter, the optical recording mediums of Examples 6 to 10 and Comparative Example 2 were prepared by being left at 45 ° C. for 24 hours.

<Recording and evaluation>
For each of the produced optical recording media, a collinear hologram recording / reproduction tester (manufactured by Pulstec Industrial Co., Ltd., SHOT-1000) is used to write a hologram at the recording spot size (diameter 200 μm) at the focal position of the recording hologram. The recording was fixed (heat ray cut filter HA50, exposure time 10 minutes, light intensity 1.5 mJ / cm ² ) by an irradiator (Hushio Corporation, HB-25103BY type). Thereafter, the recording storability was evaluated as follows. The results are shown in Table 1.

-Evaluation of record preservation-
Each optical recording medium on which the hologram was written was left in an oven at 85 ° C. for 24 hours, and the brightness of the recording was evaluated again with a collinear hologram recording / reproduction tester (manufactured by Pulstec Industries, Ltd., SHOT-1000). Assuming that the initial brightness is μ _ON 0h and 24 hours later, μ _ON 24h, the recording storability is expressed as the remaining rate expressed by the following Equation 1.
<Formula 1>
Residual rate (%) = (μ _ON 24h / μ _ON 24h) × 100

From the results in Table 1, the optical recording media of Examples 6 to 10 using the holographic recording compositions of Examples 1 to 5 are the same as those of Comparative Example 2 using the holographic recording composition of Comparative Example 1. It is recognized that the storage stability of the recording with respect to heat is higher than that of the optical recording medium.
Here, the allowable threshold for reading the recording light is considered that the remaining rate of 70% is a practical level limit in consideration of the accuracy of the recorded data. Therefore, in Comparative Example 2, the remaining rate is 60%, It has low shelf life. On the other hand, in Examples 6 to 10, the remaining rate is 85% or more, which clearly exceeds the threshold value, so that the storage stability of the record is high.

  The optical recording composition of the present invention is suitably used for various volume hologram type optical recording media having excellent storage stability against heat and capable of high-density image recording.

FIG. 1 is a schematic sectional view showing an example of an optical recording medium according to the first embodiment of the present invention. FIG. 2 is a schematic sectional view showing an example of an optical recording medium according to the second embodiment of the present invention. FIG. 3 is an explanatory diagram showing an example of an optical system around the optical recording medium according to the present invention. FIG. 4 is a block diagram showing an example of the overall configuration of an optical recording / reproducing apparatus equipped with the optical recording medium of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower substrate 2 Reflective film 3 Servo bit pattern 4 Recording layer 5 Upper substrate 6 Filter layer 7 Second gap layer 8 First gap layer 12 Objective lens 13 Dichroic mirror 14 Detector 15 1/4 wavelength plate 16 Polarizing plate 17 Half Mirror 20 Optical recording medium 21 Optical recording medium 22 Optical recording medium 31 Pickup 81 Spindle 82 Spindle motor 83 Spindle servo circuit 84 Drive device 85 Detection circuit 86 Focus servo circuit 87 Tracking servo circuit 88 Slide servo circuit 89 Signal processing circuit 90 Controller 91 Scanning Part 100 Optical recording / reproducing device A Input / output surface FE Focus error signal TE Tracking error signal RF reproduction signal

Claims (12)

A composition for holographic recording, comprising at least a monomer represented by the following structural formula (1).
However, in said structural formula (1), X represents the radically polymerizable organic group. Y represents a divalent or higher valent organic linking group. Z represents an organic group capable of ring-opening polymerization. n and m each represent an integer of 1 or more.   The holographic recording composition according to claim 1, wherein X in the structural formula (1) is any one of a (meth) acryloyloxy group, a (meth) acrylamino group, and a styryl group.   The holographic recording composition according to claim 1, wherein Z in the structural formula (1) is either an oxirane group or an oxetane group.   The holographic recording composition according to any one of claims 1 to 3, wherein Y in the structural formula (1) is a divalent or higher-valent organic linking group containing at least one benzene skeleton.   The holographic recording composition according to any one of claims 1 to 4, further comprising a matrix and a photopolymerization initiator.   The holographic recording composition according to claim 5, wherein the matrix has an organic group capable of binding by reacting with any of X and Z of the monomer represented by the structural formula (1).   The holographic recording composition according to claim 6, wherein the bondable organic group in the matrix is any one of an organic group capable of radical polymerization and an organic group capable of cationic polymerization.   The photopolymerization initiator is composed of a mixture of two or more photopolymerization initiators, and the mixture contains at least one radical polymerization initiator and at least one ring-opening polymerization initiator. A composition for holographic recording according to claim 1.   The holographic recording composition according to claim 1, wherein the content of the monomer represented by the structural formula (1) in the holographic recording composition is 1 to 50% by mass. A method for producing the holographic recording composition according to claim 1, comprising:
A matrix forming step of forming a matrix;
A recording and fixing step of recording information and fixing the recording by irradiating light to the obtained matrix and the monomer represented by the following structural formula (1) to cause radical polymerization and ring-opening polymerization. A method for producing a holographic recording composition.
However, in said structural formula (1), X represents the radically polymerizable organic group. Y represents a divalent or higher valent organic linking group. Z represents an organic group capable of ring-opening polymerization. n and m each represent an integer of 1 or more.   An optical recording medium comprising a holographic recording layer comprising the holographic recording composition according to claim 1. The optical recording medium according to claim 11, comprising a lower substrate, a filter layer, a holographic recording layer, and an upper substrate.