JP5310307B2 - Optical recording layer forming composition and optical recording medium using the same - Google Patents

Description

  The present invention relates to an optical recording layer forming composition and an optical recording medium using the same.

2. Description of the Related Art In recent years, a hologram type optical recording medium that records information as a hologram by changing the refractive index of the recording layer according to the light intensity distribution due to the interference of light toward further increase in capacity and density of the optical recording medium. Has been developed.
A hologram whose thickness is sufficiently thick with respect to the interference fringe spacing (usually a thickness of 5 times the interference fringe spacing or about 1 μm or more) is called a volume hologram, and can be recorded in the thickness direction. The larger the film thickness, the higher the density recording is possible.

As an example of a known volume phase hologram recording material, there is a write-once type that does not require wet treatment or bleaching treatment, and its composition is generally a resin matrix in which a photoactive compound is compatible. For example, there is a photopolymer system in which a monomer capable of radical polymerization or cationic polymerization is combined with a resin matrix (Patent Documents 1 and 2).
When recording information in hologram recording, when object light and reference light are irradiated, interference fringes composed of a bright part and a dark part are formed on the recording layer. For example, when the photoactive compound is a radical polymerizable compound, in the bright part, the photopolymerization initiator absorbs light and changes to a radical active species. This radical active species undergoes an addition reaction with a neighboring radical polymerizable compound, and the addition product is changed to a radical active species. Further, the addition product that has become the radical active species undergoes an addition reaction with a neighboring radical polymerizable compound. By repeating this series of photopolymerization reactions, a bright polymer is generated in the recording layer. On the other hand, the radical polymerizable compound has a concentration gradient in the light portion polymerization reaction, and the radical polymerizable compound in the dark portion of the recording layer diffuses and moves to the bright portion, and conversely, other components in the light portion. Diffuses to the dark. Thereby, the bright part and dark part of an interference fringe are comprised by a different compound, and come to have a different refractive index. As a result, the hologram optical recording medium holds this refractive index difference as information.

  The photopolymer method is a practical and promising method that can achieve both high diffraction efficiency and dry processing, but has high sensitivity in recording, sufficient diffraction efficiency, and high S / N ratio, achieving high multiplicity. There is a demand for a recording signal that is excellent in stability and reliability of a recording signal. In order to achieve these, various studies have been made on the composition of the recording composition and the production method of the medium.

For example, Patent Document 3 discloses that by optimizing the alkyl chain length in the three-dimensional cross-linked resin matrix structure having a specific structure, the mobility of the radical polymerizable compound is ensured, and “high recording capacity and high refraction” are obtained. It is disclosed that a “hologram recording medium” with a rate modulation and a small volume change by light irradiation ”is provided.
Further, Patent Document 4 describes that “instead of a matrix formed by conventional polymerization” for the purpose of suppressing variations in characteristics of recording layers due to variations in production processes and differences in materials used and volume shrinkage during recording. Thus, a method is disclosed in which a “microscopic phase separation structure of several nm to several tens of nm” is formed from a block copolymer or a graft polymer, and a photopolymerizable monomer is contained in a part of the microphase separation structure. Among the microphase-separated structures, consisting of a polymer with a high glass transition point, “The matrix is stiffer, so volume shrinkage during recording can be suppressed, and the photopolymerizable monomer exists in a softer phase with a small glass transition point. Therefore, since the diffusion of the photopolymerizable monomer occurs quickly during recording, the above-mentioned problem can be solved more efficiently.

JP 11-352303 A JP 2005-43862 A JP 2008-152041 A JP 2005-283766 A

  Conventionally, a resin matrix for such an optical recording medium, particularly a hologram recording medium, in which a polyurethane is formed by reacting a polyol and a polyisocyanate has been widely used. Considering the durability and stability of the recording medium, a resin matrix that is three-dimensionally cross-linked is often selected. On the other hand, due to the formation of crosslinks, mass transfer in the matrix is limited, and sufficient recording performance may not be exhibited.

For example, when a low-shrinkage medium is intended, the molecular weight of the polymerizable monomer (photoactive compound) used for hologram recording is preferably large to some extent. However, such a polymerizable monomer is sufficiently limited in mass transfer within the matrix. Recording performance could not be achieved.
In general, the durability and reliability of the medium can be improved by raising the glass transition temperature of the matrix. However, if the glass transition temperature is raised too much, mass transfer in the matrix is still suppressed, and the dynamic range and sensitivity of recording can be reduced. Problems such as lowering of the temperature occur.

In other words, improvement in the durability and reliability of the medium and improvement in the recording performance of the medium are not necessarily compatible, but rather considered as a conflicting issue, and a matrix that can improve the recording performance while ensuring the reliability of the recording medium. Was desired.
Patent Document 3 is an attempt to suppress a volume change during recording by using a matrix having a specific structure and to improve the recording capacity (recording density) as a result, but M / # which can be a measure of the recording density. (M number) is still not enough. In Patent Document 4, the recording layer is phase-separated by using a non-crosslinked block polymer or graft polymer in the recording layer matrix, and the recording sensitivity is improved by unevenly distributing the photoreactive monomer in one phase. However, although it has been shown that recording can be performed with a constant sensitivity as a result, there is no explicit mention as to whether a sufficient recording density can be secured. In addition, although it is a well-known fact that a phase separation structure can be expressed using a block polymer or the like, in order to obtain a desired phase separation structure size or phase separation form, the molecular weight of the block polymer, It is necessary to optimally adjust each segment molecular weight and structure, and various conditions for forming a phase separation structure. Furthermore, in order to make the polymerizable compound unevenly distributed in one phase, it is necessary to greatly increase the affinity between the polymerizable compound and each phase, and considering the realization of such a system, hologram recording It is considered to be quite difficult to stably obtain a recording layer that can be used for recording.

  The present invention has been made in view of the above problems, and an object of the present invention is to achieve both the reliability of the optical recording medium and the improvement of the recording performance.

As a result of intensive studies to solve the above problems, the present inventors,
Composition for forming an optical recording layer comprising a three-dimensionally crosslinked resin matrix-forming component and a compound having only one functional group capable of reacting with the three-dimensionally crosslinked resin matrix and having a molecular weight of 300 or more or a number average molecular weight of 300 or more (compound A) It has been found that excellent recording performance can be obtained even when the recording layer has a high glass transition temperature by using the product, and the present invention has been achieved. That is, the gist of the present invention is as follows.

[1] A composition for forming an optical recording layer comprising a three-dimensional crosslinked resin matrix-forming component, the following compound A, a photoactive compound, and a photopolymerization initiator.
Compound A: As a functional group capable of reacting with the three-dimensional crosslinked resin matrix , a hydroxyl group, amino
Group, isocyanate group, carboxyl group, having only one mercapto group or an epoxy group, molecular weight 5 00 or more, or a number average molecular weight 5 00 or more, a molecular weight of 100,000 or less, or a number average molecular weight of 100,000 or less of the compound.
[2] The composition for forming an optical recording layer according to [1], wherein the compound A is a monofunctional alcohol.
[ 3 ] The composition for forming an optical recording layer according to [1] or [2] , wherein the content of Compound A is 1% by weight or more based on the entire composition.

[4] three-dimensional crosslinked matrix forming component comprises isocyanate groups in the molecule, a hydroxyl group, an epoxy group, a compound containing two or more functional groups selected from the group consisting of amino and carboxyl groups, [1] - [3 ] The composition for optical recording layer formation as described in any one of these .
[ 5 ] The composition for forming an optical recording layer according to any one of [1] to [ 4 ], wherein the photoactive compound has a molecular weight of 200 or more.

[6] An optical recording medium using the composition for forming an optical recording layer according to any one of [1] to [ 5 ] for the recording layer .

  In the compound A and the graft chain in the present invention, “molecular weight 300 or more or number average molecular weight 300 or more” means that the compound A or the graft chain has no molecular weight distribution (absolute). It means that the molecular weight is 300 or more, and when the compound A or the graft chain has a molecular weight distribution, it means that the polystyrene standard number average molecular weight by the GPC method is 300 or more.

  According to the present invention, a medium excellent in recording performance can be obtained without impairing the reliability of the optical recording medium, for example, even when the heat resistance or glass transition temperature of the medium is increased.

In Example 1, it is a schematic diagram which shows the outline | summary of the structure of the apparatus used for hologram recording, (a) A figure shows the whole apparatus, (b) A figure shows the surface of an LED unit, (c) Figure FIG. 3 is a diagram showing an array of LEDs. It is a schematic diagram which shows the structure of the medium for a measurement produced in the Example.

  Hereinafter, the best mode (embodiment) for carrying out the present invention will be described. The following description is an example (representative example) of the embodiment of the present invention, and the present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist. . Further, the drawings used are used for explaining the embodiments of the present invention, and do not represent actual sizes.

[I. Optical recording layer forming composition]
The composition for forming an optical recording layer of the present invention comprises a three-dimensional crosslinked resin matrix-forming component, the compound A, a photoactive compound, and a photopolymerization initiator.
Compound A: a functional group capable of reacting with the three-dimensional cross-linking resin matrix, a hydroxyl group, an amino group, an isocyanate group, a carboxyl group, having only one mercapto group or an epoxy group, molecular weight 5 00 or more, or a number average molecular weight 5 00 or more, A compound having a molecular weight of 100,000 or less or a number average molecular weight of 100,000 or less .

[I-1. Three-dimensional cross-linked resin matrix forming component]
Generally, a three-dimensionally cross-linked resin is insoluble in a solvent, and its shape is easily maintained even at a high temperature, which contributes to improving the durability of the recording layer itself. Further, since the movement of the matrix-forming molecules is suppressed by the crosslinking, the volume change during recording can be reduced.
The matrix resin is compatible with a polymerizable photoactive compound described later, and has a role of maintaining adhesion to a substrate that maintains a film shape, protects and reinforces the recording layer, and maintains a flat shape. In addition, it is required to have excellent compatibility with a photopolymerization initiator and the like. If the compatibility between the matrix resin and these components is low, an interface will be created between the materials, and light will be refracted or reflected at the interface, causing light to leak to unnecessary parts, causing interference fringes to be distorted or cut off. Information is deteriorated by being recorded in an inappropriate part. The compatibility between the matrix resin and the other components is, for example, as described in Japanese Patent No. 3737306, and the scattered light intensity obtained by installing a detector with the transmitted light and angle with respect to the sample. It can be evaluated based on the above.

  The three-dimensional crosslinked resin matrix-forming component of the present invention is particularly limited as long as it can maintain sufficient compatibility with the photoactive compound and the photopolymerization initiator even after three-dimensional crosslinking as described above. Preferably, it can be arbitrarily selected from compounds containing two or more functional groups selected from the group consisting of isocyanate groups, hydroxyl groups, epoxy groups, amino groups and carboxyl groups in the molecule.

  These compounds can be used alone or in combination, and further as a component for forming a matrix by reaction with other compounds. That is, a compound containing an isocyanate group and a compound having active hydrogen in the molecule, for example, a compound containing a hydroxyl group, a thiol group, an amino group, or a carboxyl group is combined to form a urethane bond, a thiourethane bond, a urea bond, an amide bond, etc. A combination of a hydroxyl group-containing compound and a carboxyl group-containing compound to form an ester bond, a combination of an amino group-containing compound and a carboxyl group-containing compound to form an amide bond, and reaction between epoxy groups to produce an ether bond. Forming a bond, forming an ether bond by a combination of an epoxy group and a hydroxyl group, forming an amine by a combination of an epoxy group and an amino group, forming an amide bond by a combination of an amino group and a carboxyl group, and This The like can be considered to be a plurality of kinds of bond formation including al.

Above all, a system containing a polyisocyanate and a compound having two or more active hydrogen atoms in the molecule is capable of forming a matrix at a relatively low temperature and has a high degree of freedom in selecting a composition and a matrix structure. preferable.
I-1-1: Polyisocyanate A polyisocyanate that can be used in a reaction between isocyanate groups such as isocyanate-hydroxyl reaction, isocyanate-amine reaction, isocyanate-thiol reaction or biuret reaction has two or more isocyanate groups in one molecule. If it has, the kind will not be restrict | limited in particular. The number of isocyanate groups in one molecule is not particularly limited as long as it is usually 2 or more. If the number of isocyanate groups is small, the hardness required for the matrix may not be obtained. On the other hand, the upper limit of the number of isocyanate groups is not particularly limited, but is usually preferably 5 or less. If the number of functional groups is too large, functional groups remaining during the matrix forming reaction are likely to be generated. For example, if a large number of isocyanate groups remain in the matrix, the storage stability of the matrix may be deteriorated.

Examples of polyisocyanates used in the invention include hexamethylene diisocyanate, lysine methyl ester diisocyanate, aliphatic isocyanates such as 2,4,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), Alicyclic isocyanates such as 1,3-bis (isocyanatomethyl) cyclohexane, tolylene-2,4-diisocyanate, tolylene-
Examples include aromatic isocyanates such as 2,5-diisocyanate, tolylene-2,6-diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene-1,5′-diisocyanate, and multimers thereof. Among these multimers, a 3-7 mer is preferable. Moreover, the reaction material with polyhydric alcohols, such as water, a trimethylol ethane, a trimethylol propane, etc. are mentioned. Among these, tolylene diisocyanate, hexamethylene diisocyanate, and multimers thereof, or derivatives thereof are particularly preferable.

  Also, polyisocyanates (prepolymers) having a polyfunctional terminal isocyanate group can be used by reacting the above isocyanates with a compound having two or more active hydrogens in the molecule. Compounds having two or more active hydrogens in the molecule include ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, polytetramethylene glycol, ethylenediamine, isophoronediamine, 4 4,4'-diaminodicyclohexylmethane, polyols described below, and the like can be used.

  The average molecular weight of the compound having an isocyanate group is preferably from 100 to 50,000, more preferably from 150 to 10,000, and even more preferably from 150 to 5,000 in terms of number average. If it is 100 or less, the crosslink density increases, so that the hardness of the matrix and the glass transition temperature become too high, and the recording speed may decrease. On the other hand, if it is 10,000 or more, the compatibility with other components may be reduced, or the crosslinking density may be lowered, so that the hardness of the matrix and the glass transition temperature may become too low, and the recorded content may become unstable or disappear.

In addition, the compound which has an isocyanate group may contain components other than an isocyanate group in the range which does not impair the effect of this invention remarkably.
I-1-2: Compound containing two or more active hydrogens in the molecule In the present invention, active hydrogen means hydrogen contained in a functional group capable of reacting with an isocyanate group, and these functional groups include a hydroxyl group, Examples include an amine functional group, a carboxyl group, and a thiol group. That is, the compound containing two or more active hydrogens in the molecule refers to a compound having two or more of these functional groups in the molecule. Examples of these compounds are shown below.

I-1-2-1: Polyol The type of polyol that can be used in the isocyanate-hydroxyl reaction is not particularly limited as long as it has two or more hydroxyl groups in one molecule. The number of hydroxyl groups in one molecule is not particularly limited as long as it is usually 2 or more. If the number of hydroxyl groups is small, the hardness required for the matrix may not be obtained. On the other hand, the upper limit of the number of hydroxyl groups is not particularly limited, but is usually preferably 7 or less. If many hydroxyl groups remain in the matrix, the hygroscopicity of the matrix becomes high, which may affect the storage stability of the record.

  Examples of polyols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene Glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, decamethylene glycol, polyethylene glycol, polyoxyethylene triol, polypropylene glycol, polyoxypropylene triol, polyoxypropylene hexaol, polytetramethylene glycol, polyester polyol , Polycaprolactone polyol, polycarbonate polyol, polyether polyol, glycerin, trimethylolpropane, pentaerythritol, dipen Erythritol, and the like.

  The average molecular weight of the polyol is preferably from 100 to 50,000 in terms of number average, more preferably from 150 to 10,000, and even more preferably from 150 to 5,000. If it is 100 or less, the crosslinking density increases, so that the hardness of the matrix becomes too high, and the recording speed may decrease. On the other hand, if it is 50000 or more, the compatibility with other components is lowered, or the crosslinking density is lowered, so that the hardness of the matrix becomes too low and the recorded content may be lost.

In addition, the usage-amount of a polyol is the range with respect to the number-of-moles of an isocyanate group normally 0.1 equivalent or more, especially 0.7 equivalent or more, and usually 2.0 equivalent or less, especially 1.5 equivalent or less is preferable. If the amount used is too small or too large, the number of unreacted functional groups is large, and storage stability may be lost.
I-1-2-2: amine As the compound that can be reacted with isocyanate, an amine compound can also be used.

  Examples of compounds having two or more amino groups in one molecule include aliphatic amines such as ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, isophoronediamine, menthanediamine, 4,4′-diaminodicyclohexylmethane, etc. And aromatic amines such as m-xylylenediamine, diaminodiphenylmethane, and m-phenylenediamine.

  The average molecular weight of the compound having an amino group is preferably from 100 to 50,000, more preferably from 150 to 10,000, and even more preferably from 150 to 5,000 in terms of number average. If it is 100 or less, the crosslinking density increases, so that the hardness of the matrix becomes too high, and the recording speed may decrease. On the other hand, if it is 50000 or more, the compatibility with other components is lowered, or the crosslinking density is lowered, so that the hardness of the matrix becomes too low and the recorded content may be lost.

The amount of amine used is usually in the range of 0.1 equivalents or more, especially 0.7 equivalents or more, and usually 2.0 equivalents or less, especially 1.5 equivalents or less in terms of the number of moles of isocyanate groups or epoxy groups. preferable. If the amount used is too small or too large, the number of unreacted functional groups is large, and storage stability may be lost.
I-1-2-3: Mercapto compound As a compound that can be reacted with isocyanate, a mercapto compound can also be used. For example, the type is not particularly limited as long as it has two or more thiol groups in one molecule. .

Examples of compounds having two or more thiol groups in one molecule include 1,3-butanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,2-benzenedithiol, 1,3-butanedithiol, Benzenedithiol, 1,4-benzenedithiol, 1,10-decanedithiol, 1,2-ethanedithiol, 1,6-hexanedithiol, 1,9-nonanedithiol, pentaerythritol tetrakis (3-mercaptopropionate), Pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptobutyrate), trimethylolpropane tris (3-mercaptopropionate), dipentaerythritol hexakis (3-mercaptopropionate), 1, 4-bis (3-mercap) Butyryloxy) butane, and the like.
The amount of the mercapto compound used is usually in the range of 0.1 equivalents or more, particularly 0.7 equivalents or more, and usually 2.0 equivalents or less, especially 1.5 equivalents or less in terms of the number of moles of isocyanate groups or epoxy groups. Is preferred. If the amount used is too small or too large, the number of unreacted functional groups is large, and storage stability may be lost.

I-1-3: Catalyst for matrix resin formation As described above, when these resin matrices are formed, the formation can be facilitated by using an appropriate catalyst, and the formation is promoted. There is a case. Examples of such catalysts are bis (4-t-butylphenyl) iodonium perfluoro-1-butanesulfonic acid, bis (4-t-butylphenyl) iodonium p-toluenesulfonic acid, bis (4-t-butyl) Phenyl) iodonium trifluoromethanesulfonic acid, (4-bromophenyl) diphenylsulfonium triflate, (4-t-butylphenyl) diphenylsulfonium trifluoromethanesulfonic acid, diphenyliodonium perfluoro-1-butanesulfonic acid, (4-fluoro Phenyl) diphenylsulfonium trifluoromethanesulfonic acid, diphenyl-4-methylphenylsulfonium trifluoromethanesulfonic acid, triphenylsulfonium trifluoromethanesulfonic acid, bis (alkylphenyl) iodo Catalysts based on Lewis acids such as zinc chloride, tin chloride, iron chloride, aluminum chloride, BF _3, protonic acids such as hydrochloric acid, phosphoric acid, trimethylamine, triethylamine, onium salts such as nium hexafluorophosphonic acid, Amines such as triethylenediamine, dimethylbenzylamine, diazabicycloundecene, imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, trimellitic acid 1-cyanoethyl-2-undecylimidazolylum, Examples thereof include bases such as sodium hydroxide, potassium hydroxide and potassium carbonate, and tin catalysts such as dibutyltin laurate, dioctyltin laurate and dibutyltin octoate. These catalysts are usually used in the range of 0.1 ppm to 10%, preferably in the range of 1 ppm to 5%, based on the total amount of the resin matrix forming component.

[I-2. Compound A]
Compound A is a compound having only one functional group capable of reacting with the three-dimensional crosslinked resin matrix and having a molecular weight of 300 or more or a number average molecular weight of 300 or more. In the present invention, Compound A forms a graft chain by reacting with a three-dimensional crosslinked resin matrix. That is, it has only one functional group capable of reacting with an isocyanate group, a hydroxyl group, an epoxy group, an amino group, a carboxyl group, etc. contained in the three-dimensional crosslinked resin matrix forming component, and has a molecular weight of 300 or more or a number average molecular weight of 300 or more. If it is a compound, it will not specifically limit, Arbitrary things can be selected.

Examples of such a compound A include compounds having a hydroxyl group, an amino group, an isocyanate group, a carboxyl group, a mercapto group, an epoxy group, etc. as a functional group capable of reacting with a matrix in the molecule. Among these, a compound having only one functional group capable of reacting with a hydroxyl group or an isocyanate group is preferable. Specific examples of compound A include the following compounds, but these can be used alone or in any combination and ratio of two or more.
Of course, the compound having only one functional group capable of reacting with the three-dimensional crosslinked resin matrix used in the present invention is not limited to the following examples.

<Specific Example of Compound A>
I-2-1: Monofunctional alcohol The monofunctional alcohol used in the present invention is a compound having only one hydroxyl group in the compound and no other functional group capable of reacting with the three-dimensional crosslinked resin matrix. Any compound can be used.

Examples of these include C ₂₁ -C ₅₀ linear or cyclic alkyl alcohols; C ₂₁ -C ₅₀ alkenyl alcohols; polyethylene glycol monoalkyl ethers such as polyethylene glycol monobutyl ether and polyethylene glycol monododecyl ether, polyethylene monoacetate, etc. Monofunctional polyethylene glycols typified by polyethylene monoesters of the above; monofunctional polypropylene glycols typified by polypropylene glycol monoesters such as polypropylene monoalkyl ethers such as polypropylene glycol monobutyl ether, polypropylene glycol monoacetate, polypropylene glycol monoacetate; Other monofunctional polyoxybutylene, monofunctional polycaprolactone, monofunctional poly Esters, such as mono-functional polycarbonates. Among them, it is preferable to use monools having a structure such as monofunctional polyethylene glycol, monofunctional polypropylene glycol, monofunctional polycaprolactone, and monofunctional polycarbonate.

In these, a part of the structure may be substituted. The substituent which may be substituted is an aromatic ring group, a halogen atom or the like.
The aromatic ring group includes a 5- to 6-membered monocyclic ring or a structure in which two or more of these are condensed or linked, and specifically includes 6 carbon atoms such as a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group. -15 aryl groups, pyridyl groups, carbazolyl groups, benzothiophenyl groups, dibenzothiophenyl groups and other heteroaryl groups having 3 to 14 carbon atoms.

Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom.
I-2-2: Monofunctional isocyanate The monofunctional isocyanate used in the present invention is a compound having only one isocyanate group in the molecule and no other functional group capable of reacting with the three-dimensional crosslinked resin matrix. Any compound may be used. For example, a urethane oligomer having an isocyanate group only at one end can be mentioned.
In these, a part of the structure may be substituted. The substituent which may be substituted is an aromatic ring group, a halogen atom or the like. Specific examples of the aromatic ring group and the halogen atom include those described in the section of monofunctional alcohol.

I-2-3: Monofunctional thiol The monofunctional thiol used in the present invention is a compound having only one mercapto group in the molecule and no other functional group capable of reacting with the three-dimensional crosslinked resin matrix. Any compound may be used. Examples of such compounds include monofunctional thiols having a polyoxypropylene skeleton, monofunctional thiols having a polyoxyethylene skeleton, and the like.
In these, a part of the structure may be substituted. The substituent which may be substituted is an aromatic ring group, a halogen atom or the like. Specific examples of the aromatic ring group and the halogen atom include those described in the section of monofunctional alcohol.

I-2-4: Monofunctional amine The monofunctional amine used in the present invention has only one primary or secondary amino group in the molecule and another functional group capable of reacting with the three-dimensional crosslinked resin matrix. Any compound may be used as long as it is not a compound. Examples of such compounds include
C ₂₁ -C ₅₀ primary amines such as optionally substituted alkylamines or optionally substituted (hetero) arylamines; optionally substituted dialkylamines , C ₂₁ -C ₅₀ secondary amines such as (hetero) arylalkylamines optionally having substituents and di (hetero) arylamines optionally having substituents.

Examples of the alkyl group of the alkylamine, dialkylamine, and (hetero) arylalkylamine include C ₁ -C ₅₀ linear and branched C ₂₁ -C ₅₀ alkyl such as eicosyl group, docosyl group, and tetracosyl group. Groups.
The alkyl group of the alkylamine, dialkylamine, or (hetero) arylalkylamine may further have a substituent. Examples of the substituent that the alkyl group may have include an aromatic ring group and a halogen atom.

The aromatic ring group includes a 5- to 6-membered monocyclic ring or a structure in which two or more of these are condensed or linked, and specifically includes 6 carbon atoms such as a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group. -15 aryl groups, pyridyl groups, carbazolyl groups, benzothiophenyl groups, dibenzothiophenyl groups and other heteroaryl groups having 3 to 14 carbon atoms.
Examples of the halogen atom include a chlorine atom, a bromine atom, and an iodine atom.

  Next, as the (hetero) aryl group of the above (hetero) arylamine, (hetero) arylalkylamine, and di (hetero) arylamine, a 5- to 6-membered monocycle, or a structure in which two or more of these are condensed or linked Specifically, carbons such as aryl groups having 6 to 15 carbon atoms such as phenyl group, naphthyl group, anthracenyl group, biphenyl group, pyridyl group, carbazolyl group, benzothiophenyl group, dibenzothiophenyl group, etc. Examples include heteroaryl groups of 3 to 14.

The (hetero) arylamine, the (hetero) arylalkylamine and the (hetero) aryl group of di (hetero) arylamine may have a substituent, and the aromatic amine may have a substituent Is an alkyl group, an aromatic ring group, a halogen atom, or the like.
As the alkyl group, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, tert-butyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group C ₁ -C ₅₀ linear, branched or cyclic alkyl groups such as icosyl group, docosyl group, tetracosyl group, cyclopentyl group, cyclohexyl group, dicyclohexyl group and tricyclodecanyl group.
Specific examples of the aromatic ring group and the halogen atom include those exemplified as the substituent that the alkyl group of the above alkylamine, dialkylamine, and (hetero) arylalkylamine may further have.

I-2-5: Monofunctional carboxylic acid The monofunctional carboxylic acid used in the present invention is a compound having only one carboxyl group in the molecule and no other functional group capable of reacting with the three-dimensional crosslinked resin matrix. Any compound can be used. Examples of such compounds include
Alkyl carboxylic acids of _C 20 _{-C 50,} such as eicosanoic acid; arachidonic acid, docosahexaenoic acid, unsaturated carboxylic acids of _C 20 _{-C 50,} such as eicosapentaenoic acid, and the like.
These may be partially substituted with an aromatic ring or a halogen atom. The substituent which may be substituted is an aromatic ring group, a halogen atom or the like. Specific examples of the aromatic ring group and the halogen atom include those described in the section of monofunctional alcohol.

I-2-6: Monofunctional epoxy compound The monofunctional epoxy compound used in the present invention is a compound having only one oxirane ring in the molecule and having no functional group capable of reacting with the three-dimensional crosslinked resin matrix. Any compound may be used. Examples of such compounds include
C ₂₀ -C ₅₀ alkyl glycidyl ethers; C ₂₀ -C ₅₀ hydrocarbon epoxy compounds such as 1,2-epoxyeicosane, and the like.

In addition to these compounds, compounds having a skeleton such as polyester, polyether, polyethylene, polyamide, polycarbonate, polysulfone, and polyketone and having only one of the above functional groups in the molecule can also be used.
In these, a part of the structure may be substituted. The substituent which may be substituted is an aromatic ring group, a halogen atom or the like. Specific examples of the aromatic ring group and the halogen atom include those described in the section of monofunctional alcohol.
Among the compounds described above, it is preferable to use monofunctional alcohols, particularly monools having a structure such as monofunctional polyethylene, monofunctional polypropylene glycol, monofunctional polycaprolactone, and monofunctional polycarbonate.

<Molecular weight or number average molecular weight of Compound A>
These compounds have a molecular weight or number average molecular weight of 300 or more, more preferably 500 or more, and a molecular weight or number average molecular weight of 100,000 or less, preferably 50,000 or less, more preferably 10,000 or less. If the molecular weight or the number average molecular weight is too small, the boiling point of the compound may be lowered, and handling may be required. Further, there is a concern that sufficient recording performance cannot be obtained when the glass transition temperature of the recording layer is high. On the other hand, if the molecular weight or the number average molecular weight is too large, there is a concern that the compatibility with the main component of the matrix is reduced and the light transmittance of the entire matrix is reduced.

<Use amount of Compound A>
These compounds are usually used in the range of 0.1% to 90% by weight, preferably 1% to 80% by weight, more preferably 5% to 60% by weight, based on the entire matrix resin component. it can. If the amount of the compound used is too small, the curing of the present invention will not be sufficiently exerted, and if the amount used is too large, the mechanical properties of the matrix may be lowered.

[I-3. Photoactive compound]
The type of the photoactive compound used in the optical recording medium of the present invention is not particularly limited and can be appropriately selected from known compounds. Usually, a polymerizable monomer is used. Examples of the polymerizable monomer include a cation polymerizable monomer, an anion polymerizable monomer, and a radical polymerizable monomer.

I-3-1: Cationic polymerizable monomer Examples of the cationic polymerizable monomer include compounds having an oxirane ring, styrene and derivatives thereof, vinyl naphthalene and derivatives thereof, vinyl ethers, N-vinyl compounds, compounds having an oxetane ring, and the like. Can be mentioned. Among them, it is preferable to use a compound having at least an oxetane ring, and it is more preferable to use a compound having an oxirane ring together with a compound having an oxetane ring.

  Examples of the compound having an oxirane ring include a prepolymer containing two or more oxirane rings in one molecule. Examples of such prepolymers include cycloaliphatic polyepoxies, polyglycidyl esters of polybasic acids, polyglycidyl ethers of polyhydric alcohols, polyglycidyl ethers of polyoxyalkylene glycols, poly (aromatic polyols). Examples thereof include glycidyl ethers, hydrogenated compounds of polyglycidyl ethers of aromatic polyols, urethane polyepoxy compounds, and epoxidized polybutadienes. Any of these prepolymers may be used alone, or two or more thereof may be used in any combination and ratio.

Examples of styrene and its derivatives include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, p-methyl-β-methylstyrene, α-methylstyrene, p-methoxy-β-methylstyrene, divinyl Examples include benzene.
Examples of vinyl naphthalene and its derivatives include 1-vinyl naphthalene, α-methyl-1-vinyl naphthalene, β-methyl-1-vinyl naphthalene, 4-methyl-1-vinyl naphthalene, 4-methoxy-1-vinyl naphthalene. Etc.

Examples of vinyl ethers include isobutyl ether, ethyl vinyl ether, phenyl vinyl ether, p-methylphenyl vinyl ether, p-methoxyphenyl vinyl ether, and the like.
Examples of the N-vinyl compound include N-vinyl carbazole, N-vinyl pyrrolidone, N-vinyl indole, N-vinyl pyrrole, N-vinyl phenothiazine and the like.

Examples of the compound having an oxetane ring include various known oxetane compounds described in JP-A Nos. 2001-220526 and 2001-310937.
Any one of the above-exemplified cationic polymerizable monomers may be used alone, or two or more may be used in any combination and ratio.

I-3-2: Anion polymerizable monomer Examples of the anion polymerizable monomer include hydrocarbon monomers and polar monomers.
Examples of the hydrocarbon monomer include styrene, α-methylstyrene, butadiene, isoprene, vinyl pyridine, vinyl anthracene, and derivatives thereof.

Examples of polar monomers include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, and isopropyl methacrylate; acrylic acid esters such as methyl acrylate and ethyl acrylate; methyl vinyl ketone, isopropyl vinyl ketone, and cyclohexyl vinyl ketone. Vinyl ketones such as phenyl vinyl ketone; isopropenyl ketones such as methyl isopropenyl ketone and phenyl isopropenyl ketone; other polarities such as acrylonitrile, acrylamide, nitroethylene, methylene malonate, cyanoacrylate, vinylidene cyanide Monomer; and the like.
Any one of the above-exemplified anionic polymerizable monomers may be used alone, or two or more thereof may be used in any combination and ratio.

I-3-3: Radical polymerizable monomer
The radical polymerizable monomer is a compound having one or more ethylenically unsaturated double bonds in one molecule, and examples thereof include (meth) acrylic acid esters, (meth) acrylamides, vinyl esters, Examples thereof include vinyl compounds and styrenes.

  Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, (n- or i-) propyl (meth) acrylate, (n-, i-, sec- or t-). Butyl (meth) acrylate, amyl (meth) acrylate, adamantyl (meth) acrylate, chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxypentyl (meth) Acrylate, cyclohexyl (meth) acrylate, allyl (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, benzyl (meth) acrylate, methoxybenzyl (meth) acrylate, chlorobenze (Meth) acrylate, hydroxybenzyl (meth) acrylate, hydroxyphenethyl (meth) acrylate, dihydroxyphenethyl (meth) acrylate, furfuryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, phenyl (meth) acrylate, hydroxyphenyl (meth ) Acrylate, chlorophenyl (meth) acrylate, sulfamoylphenyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2- (hydroxyphenylcarbonyloxy) ethyl (meth) acrylate, phenol EO modified (meth) acrylate, parac Milphenol EO modified (meth) acrylate, nonylphenol EO modified (meth) acrylate, N-acryloyloxyethylhexahydrofur Luimide, bisphenol F EO modified diacrylate, bisphenol A EO modified diacrylate, dibromophenyl (meth) acrylate, tribromophenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl acrylate, tricyclode Candimethylol di (meth) acrylate, bisphenoxyethanol full orange (meth) acrylate, (meth) acryl compounds having a benzothiazole ring such as (meth) acryloxyphenylbenzothiazole, (meth) acryloxyphenyl thianthrene, (meth) (Meth) acrylic compounds having a thianthrene skeleton such as acryloxyphenyl bisthianthrene, (meth) acryloxyphenyl dibenzothiophene, (meth) acryloxyphenyl bisdi And (meth) acrylic compounds having a dibenzothiophene skeleton such as benzothiophene, (meth) acrylic compounds having a dibenzofuran skeleton such as (meth) acryloxyphenyldibenzofuran, and the like.

  Examples of (meth) acrylamides include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-benzyl. (Meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-phenyl (meth) acrylamide, N-tolyl (meth) acrylamide, N- (hydroxyphenyl) (meth) acrylamide, N- (sulfamoylphenyl) ( (Meth) acrylamide, N- (phenylsulfonyl) (meth) acrylamide, N- (tolylsulfonyl) (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methyl-N-phenyl (meth) acrylamide, N- Hydroxyethyl-N- Chill (meth) acrylamide.

  Examples of vinyl esters include vinyl acetate, vinyl butyrate, vinyl benzoate, vinyl benzoate, vinyl t-butyl benzoate, vinyl chlorobenzoate, vinyl 4-ethoxybenzoate, vinyl 4-ethylbenzoate, 4- Examples include vinyl methylbenzoate, vinyl 3-methylbenzoate, vinyl 2-methylbenzoate, vinyl 4-phenylbenzoate, and vinyl pivalate. Examples of vinyl compounds other than vinyl esters include N-vinylcarbazole.

  Examples of styrenes include styrene, p-acetylstyrene, p-benzoylstyrene, 2-butoxymethylstyrene, 4-butylstyrene, 4-sec-butylstyrene, 4-tert-butylstyrene, 2-chlorostyrene, 3 -Chlorostyrene, 4-chlorostyrene, dichlorostyrene, 2,4-diisopropylstyrene, dimethylstyrene, p-ethoxystyrene, 2-ethylstyrene, 2-methoxystyrene, 4-methoxystyrene, 2-methylstyrene, 3-methyl Examples thereof include styrene, 4-methylstyrene, p-methylstyrene, p-phenoxystyrene, p-phenylstyrene, and the like.

Any one of the radically polymerizable monomers exemplified above may be used alone, or two or more thereof may be used in any combination and ratio.
Any of the above-exemplified cationic polymerizable monomers, anionic polymerizable monomers, and radical polymerizable monomers may be used, or two or more of them may be used in combination. However, it is preferable to use a radical polymerizable monomer as the photoactive compound because it is difficult to inhibit the reaction forming the resin matrix.

<Molecular weight of photoactive compound>
The photoactive compound used in the composition for forming a hologram recording layer of the present invention usually has a molecular weight of 200 or more and 5000 or less from the viewpoint of reducing shrinkage due to crosslinking during light irradiation and securing mobility in the recording layer. Among these, the molecular weight is preferably 250 or more and 3000 or less, more preferably 300 or more and 2000 or less.
If the molecular weight of the photoactive compound is too small, the volume change (shrinkage rate, etc.) during recording may be too large compared to the content of the photoactive compound, resulting in a decrease in recording signal quality and recording density. Invite In addition, when the molecular weight of the photoactive compound is too large, there is a concern that the diffusion of the compound in the matrix is excessively suppressed and the recording sensitivity and the recording density are lowered.

<Content of photoactive compound>
The content of the photoactive compound is usually 0.1 to 80% by weight, preferably 1 to 50% by weight, based on the entire composition for forming an optical recording layer. If the content is too small, sufficient recording sensitivity and recording density cannot be ensured. If the content is too large, the quality of the recording signal may be lowered, or the stability of the recording layer may be impaired.

[I-4. Photopolymerization initiator]
Any photopolymerization initiator can be used as long as it is a known radical photopolymerization initiator. Examples include azo compounds, azide compounds, organic peroxides, organoborates, onium salts, bisimidazole derivatives, titanocene compounds, iodonium salts, organic thiol compounds, halogenated hydrocarbon derivatives, and the like. Any one of these may be used alone, or two or more may be used in any combination and ratio. Among these, titanocene compounds, acylphosphine oxide compounds, oxime ester compounds, and the like are preferable as the photopolymerization initiator because a polymerization reaction is caused by light in a wavelength region of 400 nm or more.

I-4-1: Titanocene compound
When a titanocene compound is used as a photopolymerization initiator, the kind thereof is not particularly limited. For example, various titanocene compounds described in JP-A Nos. 59-152396 and 61-151197 are disclosed. Can be appropriately selected and used.
Specific examples of the titanocene compound include di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, and di-cyclopentadienyl-Ti-bis-2,3,4. , 5,6-pentafluorophen-1-yl, dicyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti-bis- 2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,6-di-fluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2 , 4-di-fluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl- T -Bis-2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,6-difluorophen-1-yl, di-cyclopentadienyl-Ti -Bis-2,6-difluoro-3- (pyro-1-yl) -phen-1-yl and the like.

I-4-2: Acylphosphine oxide compound
Specific examples of the acylphosphine oxide compound include a monofunctional initiator having only one light-emitting cleavage point in one molecule, and a bifunctional initiator having two light-exciting points in one molecule. Can be mentioned.
Examples of such monofunctional initiators include triphenyl phosphine oxide, 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, 2,6-dichlorobenzoyl diphenyl phosphine oxide, and the like.

Examples of the bifunctional initiator include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,6 dichlorobenzoyl) -4-propylphenylphosphine euside, bis (2,6 dichlorobenzoyl) -2,5 dimethylphenylphosphine oxide, and the like.

I-4-3: Oxime ester compound
Specific examples of the oxime ester compound include those having the following structures.

Specifically, 1- [4- (phenylthio) -2- (O-benzoyloxime)]-1,2-octanedione, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole -3-yl] -1- (O-acetyloxime) ethanone and the like.
I-4-4: Content of photopolymerization initiator
Any one of the various photopolymerization initiators described above may be used alone, or two or more thereof may be used in any combination and ratio.

  The content of the photopolymerization initiator in the composition for forming a hologram recording layer of the present invention can be arbitrarily selected according to its use. When the photoreactive composition of the present invention is used for forming a hologram recording layer, the content of the photopolymerization initiator in the photoreactive composition is usually 0.01% by weight relative to the entire photoreactive composition. % Or more, preferably 0.05% by weight or more, and usually 20% by weight or less, particularly preferably 15% by weight or less. If the content of the photopolymerization initiator is too small, the amount of polymerization initiation species is reduced, so that the rate of photopolymerization is slowed and the hologram recording sensitivity may be lowered. On the other hand, if the content of the photopolymerization initiator is too large, polymerization initiation species generated by light irradiation recombine with each other or disproportionation occurs, so that the contribution to photopolymerization is reduced, and the hologram recording sensitivity is also reduced. May decrease. When two or more photopolymerization initiators are used in combination, the total amount thereof satisfies the above range.

I-4-5: Absorption wavelength region of photopolymerization initiator The absorption wavelength region of the photopolymerization initiator constituting the composition for forming a hologram recording layer of the present invention is usually 340 nm or more, preferably 350 nm or more, The absorption is usually 800 nm or less, preferably 650 nm or less. For example, when the light source is a blue laser, the absorption is preferably at least 350 to 430 nm, and when the light source is a green laser, the absorption is preferably at least 500 to 550 nm. When the absorption wavelength region is different from the above range, the sensitivity tends to be lowered because the irradiated light energy is not easily used for the photopolymerization reaction.

The absorption spectrum of the photopolymerization initiator can be easily measured, for example, by measuring a solution obtained by dissolving the photopolymerization initiator in a tetrahydrofuran solvent so as to have a concentration of about 10 ⁻⁵ mol with a normal ultraviolet or visible light absorption spectrum meter. Is required.
I-4-6: Optional component of photopolymerization initiator As the photopolymerization initiator used in the composition for forming a hologram recording layer of the present invention, the above-mentioned photopolymerization initiator can be used alone, but as necessary. Also, other photopolymerization initiators can be used in combination.

  Examples of other photopolymerization initiators include acetophenones, benzophenones, hydroxybenzenes, thioxanthones, anthraquinones, ketals, hexaarylbiimidazoles, titanocenes, acylphosphine oxides, and halogenated hydrocarbon derivatives. , Organoborates, organic peroxides, onium salts, sulfone compounds, carbamic acid derivatives, sulfonamides, triarylmethanols, and the like. Any one of these may be used alone, or two or more may be used in any combination and ratio.

  The blending amount of other photopolymerization initiators (the total amount when two or more are combined) is arbitrary as long as it does not impair the function of the photopolymerization initiator of the present invention. The ratio to the whole composition is usually 0.001% or more, particularly 0.01% by weight or more, and usually 20% by weight or less, especially 15% by weight or less. Further, the total amount with the photopolymerization initiator of the present invention should not exceed 25% by weight.

[I-5. Other ingredients]
In addition, the composition for forming a hologram recording layer of the present invention may contain other components in addition to the above-mentioned photoactive compound, photopolymerization initiator, and resin matrix, as long as not departing from the spirit of the present invention. Good.
For example, with respect to hologram recording, it is important to control the photoreaction that occurs in the bright part during recording, so it is preferable to add an additive that can control the polymerization. Additives capable of controlling the polymerization include compounds having a terpenoid skeleton, cyclic having at least two or more double bonds, and the positions of the double bonds in the relative positions 1, 4 or non- Examples include cyclic compounds, allyl compounds, mercapto compounds, amine compounds, and phenols.

Further, the composition for forming a hologram recording layer of the present invention may contain any additive as required for controlling the excitation wavelength and excitation energy of the sensitizer, controlling the reaction, improving the characteristics, etc. it can.
Examples of such additives include the following compounds.
Examples of the compound that controls excitation of the sensitizer include a sensitizer and a sensitizer.

As the sensitizer, any of various known sensitizers can be selected and used. Depending on the wavelength of the laser beam used for recording and the type of initiator used, a green laser is used. In the case of the system used, specific examples of preferable sensitizers include compounds described in JP-A-5-241338, JP-A-2-69, JP-B-2-55446, and the like. In the case of a system to be used, JP-A No. 2000-10277, JP-A No. 2004-198446, JP-A No. 2005-62415, JP-A No. 2005-91593, JP-A No. 2004-191938, JP-A No. 2004-2004. No. 272212, JP-A No. 2004-221958, JP-A No. 2004-252421, JP-A No. 2005-107191, JP-A No. 2004-264834 Compounds that are described in. Any of the various sensitizers exemplified above may be used alone, or two or more may be used in any combination and ratio.

  When the obtained optical recording medium or optical recording material is required to be colorless and transparent, it is preferable to use a cyanine dye as a sensitizer. That is, since cyanine dyes are generally easily decomposed by light, post-exposure is performed, that is, by leaving them for several hours to several days under room light or sunlight, the cyanine dyes in an optical recording medium or optical recording material are used. The dye is decomposed and has no absorption in the visible range, and a colorless and transparent optical recording medium or optical recording material is obtained.

The amount of the sensitizer needs to be increased or decreased depending on the thickness of the recording layer to be formed. It is preferably 10% by weight or less, more preferably 5% by weight or less. If the amount of the sensitizer used is too small, the starting efficiency is lowered, and recording may take a long time. On the other hand, if the amount of the sensitizer used is too large, the absorption of light used for recording and reproduction increases, which may make it difficult for light to reach in the depth direction. When two or more sensitizers are used in combination, the total amount thereof satisfies the above range.

As additives other than those described above, plasticizers for improving reaction efficiency and adjusting physical properties of the recording layer, additives for controlling the water absorption rate of the recording layer, and the like can be used.
Examples of plasticizers include dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, bis (2-ethylhexyl) adipate, diisononyl adipate, di-n-butyl adipate, etc. Adipates, dioctyl sebacate, sebacates such as dibutyl sebacate, phosphates such as tricresyl phosphate, citrates such as acetyl tributyl citrate, trimellitic acids such as trioctyl trimellitic acid Esters, epoxidized soybean oil, chlorinated paraffin, alkoxylated (poly) alkylene glycol esters such as acetoxymethoxypropane, terminal alkoxylated polyalkylene glycols such as dimethoxypolyethylene glycol, etc. It is below.

  These plasticizers are generally used in the range of 0.01% by weight or more and 50% by weight or less, preferably 0.05% by weight or more and 20% by weight or less as a ratio to the whole photoreactive composition. If the amount of these plasticizers is less than this, the effect on improving the reaction efficiency and adjusting the physical properties will not be exhibited, and if it is more than this amount, the transparency of the recording layer will be lowered or the bleedout of the plasticizer will be noticeable. It is not preferable.

Furthermore, a compound used for controlling the reaction can also be added. Examples of this case include polymerization initiators, chain transfer agents, polymerization terminators, compatibilizing agents, reaction aids, and the like.
Specific examples thereof include amine compounds such as triethylamine, triphenylamine, diethylamine, dimethylbenzylamine, aniline, p-methoxyphenol, 2,6-di-t-butyl-p-cresol, 2,4,6-trimethylphenol. , Benzylaminophenol, dihydroxybenzene, pyrogallol, resorcinol and other phenols, benzoquinone, hydroquinone and other quinones, nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-dinitrobenzene and other nitro compounds, allyl acetate, butane Allyl compounds such as allyl acid, diethyl diallylmalonate, allylbenzene, allyl alcohol, allylamine, thiols such as benzenethiol, benzyl mercaptan, dodecanethiol, diphth Disulfides, sulfides such as dibenzyl disulfide, butyl disulfide, terpinolene, alpha-terpenoids such as terpinene, 1,4-dienes such as 1,4-cyclohexadiene and the like.

In addition, examples of additives that may be required for improving properties include dispersants, antifoaming agents, plasticizers, preservatives, stabilizers, antioxidants, ultraviolet absorbers, and the like.
Any one of these additives may be used alone, or two or more thereof may be used in any combination and ratio.
The use amount of these additives is usually 0.0005% by weight or more, particularly 0.001% by weight or more, and usually 30% by weight or less, based on the ratio of the composition for forming a hologram recording layer of the present embodiment. Especially, it is preferable to set it as the range of 10 weight% or less. When two or more additives are used in combination, the total amount thereof satisfies the above range.

[II. Optical recording medium]
The optical recording medium of the present invention has a configuration including the recording layer for an optical recording medium of the present invention. There is no restriction | limiting in the other specific structure in the optical recording medium of this invention, It is arbitrary. The optical recording medium of this embodiment is an optical recording medium having a recording layer containing at least a photoactive compound and a photopolymerization initiator in a three-dimensional crosslinked resin matrix, and the three-dimensional crosslinked resin matrix of the recording layer has a molecular weight of 300. Or a graft chain having a number average molecular weight of 300 or more.

Hereinafter, a hologram optical recording medium according to an embodiment of the present invention (this may be referred to as “optical recording medium of the present embodiment”) will be described in detail.
The recording layer for an optical recording medium of the present invention is provided. Further, the optical recording medium of the present embodiment includes a support and other layers as necessary.
As will be described in detail in the section of the recording method described later, a part of the photoactive compound contained in the recording layer undergoes a chemical change such as polymerization by hologram recording or the like. Therefore, in the hologram recording medium after recording, a part of the photoactive compound is consumed and exists as a compound after reaction such as a polymer. Although the amount of consumption of the photoactive compound is considered to vary depending on the amount of recorded information, so-called “post-exposure” in which after recording data, the remaining photoactive compound is intentionally consumed by applying uniform light to the recorded portion. In the case of undergoing such a process, most of the photoactive compound changes to a compound after the reaction.

[II-1. Recording layer]
The recording layer for optical media according to the present invention is a layer on which information is recorded by light irradiation. The information recording method is not particularly limited as long as it can be recorded based on a chemical change induced by irradiating the medium recording layer with light. For example, a method that can perform drawing, formation of dots, formation of interference fringes, and the like based on changes in refractive index and transmittance in the recording layer by irradiation of light can be used. In particular, it is suitably used for hologram recording.

  The thickness of the recording layer for an optical medium according to the present invention is not particularly limited and may be appropriately determined in consideration of a recording method or the like. Generally, it is usually 1 μm or more, preferably 10 μm or more, and usually 2 cm. Hereinafter, the range is preferably 1.5 cm or less. If the recording layer is too thick, the selectivity of each hologram may be lowered when performing recording such as hologram multiplex recording, and the degree of multiplex recording may be reduced. If the recording layer is too thin, it is difficult to uniformly form the entire recording layer, and it may be difficult to perform multiplex recording with uniform diffraction efficiency of each hologram and a high S / N ratio.

  The optical recording medium of the present invention is an optical recording medium having a recording layer containing at least a photoactive compound and a photopolymerization initiator in a three-dimensional crosslinked resin matrix, and the three-dimensional crosslinked resin matrix of the recording layer has a molecular weight of 300 or more. Alternatively, it has a graft chain having a number average molecular weight of 300 or more. The molecular weight or number average molecular weight of 300 or more of the graft chain is preferably 500 or more, and is usually 100,000 or less, preferably 50,000 or less, and more preferably 10,000 or less. If the molecular weight or the number average molecular weight is too small, there is a concern that sufficient recording performance cannot be obtained in a state where the glass transition temperature of the recording layer is high. On the other hand, if the molecular weight or the number average molecular weight is too large, there is a concern that the compatibility with the main component of the matrix is reduced and the light transmittance of the entire matrix is reduced.

  The method of forming the graft chain in the three-dimensional crosslinked resin matrix is not particularly limited. After the matrix is formed, a segment that is cleaved by heat or light to generate a polymerization initiation species such as a radical is introduced into the matrix structure. A method of forming a graft chain by cleaving the site with heat, light, etc. and growing a new polymer chain therefrom, and a branching part by coexisting with a matrix-forming component branched during the formation of a three-dimensional crosslinked resin matrix A method of forming a graft chain, a method of using a compound having only one functional group that reacts with the matrix in the formation of a three-dimensional resin matrix, and using the compound as a graft chain segment, after forming a three-dimensional resin matrix, radiation and electron beam A part of the molecule that forms the matrix by irradiating energy rays such as How to graft chains, but like any method may be used. For example, a recording layer can be formed using the above-described composition for forming an optical recording layer of the present invention.

  For example, when a matrix is formed by reacting a polyisocyanate compound (B) with a compound (C) having two or more active hydrogens in the molecule, a functional group having reactivity with a hydroxyl group or an isocyanate group is contained in the matrix. By carrying out the matrix formation reaction in the presence of the compound (A) having only one group, the graft chain derived from the compound A is introduced into the three-dimensional crosslinked resin matrix. In general, the compound (A) forms a covalent bond with the compound (B) or (C), whereby the structure of the compound (A) is included in the matrix structure. Further, the compound (A) may remain as it is without reacting with (B), (C) and the like. In either case, since the composition forming the recording layer contains the compound (A), it is suitable for the purpose of the present invention.

  Also, when the storage elastic modulus E ′, loss elastic modulus E ″ and loss tangent (E ″ / E ′ = tan δ) of the recording layer are calculated by measuring the dynamic viscoelasticity of the recording layer, and a tan δ curve is drawn The curve is usually a curve having one or more peaks. The maximum peak was taken as the main dispersion peak, and the temperature showing the peak value of the main dispersion peak was taken as the glass transition temperature of the recording layer. In this tan δ curve, a peak other than the main dispersion peak (referred to as a sub-dispersion peak) may appear, but a recording layer according to the present invention in which such a sub-dispersion peak appears is also suitable. Used.

[II-2. Support]
Usually, the optical recording medium has a support, and the recording layer and other layers are laminated on the support to constitute the optical recording medium. However, when the recording layer or other layers have the required strength and durability, the optical recording medium may not have a support.
The support is not particularly limited in detail as long as it has the required strength and durability, and any support can be used.

Specifically, although there is no restriction | limiting in the shape of a support body, Usually, it forms in flat form or a film form.
Moreover, there is no restriction | limiting in the material which comprises a support body, Transparent or opaque may be sufficient. Examples of transparent materials for the support include organic materials such as acrylic, polyethylene terephthalate, polyethylene naphthoate, polycarbonate, polyethylene, polypropylene, amorphous polyolefin, polystyrene, and cellulose acetate; and inorganic materials such as glass, silicon, and quartz. It is done. Among these, polycarbonate, acrylic, polyester, amorphous polyolefin, glass and the like are preferable, and polycarbonate, acrylic, amorphous polyolefin, and glass are particularly preferable.

On the other hand, when the opaque material is cited as a material on the support, a metal such as aluminum; a metal such as gold, silver, or aluminum, or a dielectric such as magnesium fluoride or zirconium oxide is coated on the transparent support. And the like.
Although there is no restriction | limiting in particular also in the thickness of a support body, Usually, it is preferable to set it as the range of 0.1 mm or more and 1 cm or less. If the support is too thin, the mechanical strength of the optical recording medium may be insufficient and the substrate may be warped. If the support is too thick, the amount of transmitted light may be reduced and the cost may be increased.

  Moreover, you may surface-treat on the surface of a support body. This surface treatment is usually performed to improve the adhesion between the support and the recording layer. Examples of the surface treatment include subjecting the support to corona discharge treatment or forming an undercoat layer on the support in advance. Here, examples of the composition of the undercoat layer include halogenated phenols, partially hydrolyzed vinyl chloride-vinyl acetate copolymers, polyurethane resins, and the like.

Furthermore, the surface treatment may be performed for purposes other than the improvement of adhesiveness. Examples thereof include a reflective coating treatment for forming a reflective coating layer made of a metal such as gold, silver, and aluminum; a dielectric coating treatment for forming a dielectric layer such as magnesium fluoride and zirconium oxide, and the like. It is done. These layers may be formed as a single layer or two or more layers.
Further, the support may be provided only on either the upper side or the lower side of the recording layer of the optical recording medium of the present invention, or may be provided on both. However, when providing a support on both the upper and lower sides of the recording layer, at least one of the supports is configured to be transparent so as to transmit active energy rays (excitation light, reference light, reproduction light, etc.).

In the case of an optical recording medium having a transparent support on one side or both sides of the recording layer, a transmissive or reflective hologram can be recorded. When a support having reflection characteristics on one side is used, a reflection type hologram can be recorded.
Furthermore, patterning for data addresses may be provided on the support. Although there is no restriction | limiting in the patterning method, For example, an unevenness | corrugation may be formed in support body itself, a pattern may be formed in a reflective layer (after-mentioned), and you may form by the method of combining these.
In addition to the recording layer and the support described above, other layers may be provided on the optical recording medium of the present embodiment. Examples of other layers include a protective layer, a reflective layer, an antireflection layer (antireflection film), and the like.

[II-3. Protective layer]
The protective layer is a layer for preventing adverse effects such as a decrease in sensitivity due to oxygen and moisture and a deterioration in storage stability. There is no restriction | limiting in the specific structure of a protective layer, It is possible to apply a well-known thing arbitrarily. For example, a layer made of a water-soluble polymer, an organic / inorganic material, or the like can be formed as a protective layer.

[II-4. Reflective layer]
A reflective layer can be provided on the recording medium as required.
The reflective layer is formed when the optical recording medium is configured as a reflective type. In the case of a reflective optical recording medium, the reflective layer may be formed between the support and the recording layer, or may be formed on the outer surface of the support. Usually, the support and the recording layer are used. It is preferable to be between.
Further, for both transmissive and reflective optical recording media, an antireflection film may be provided on the side on which recording light and readout light enter and exit, or between the recording layer and the support. The antireflection film functions to improve light utilization efficiency and suppress the generation of ghost images.

[II-5. Production method]
There is no particular limitation on the method of manufacturing the optical recording medium of the present embodiment, and it can be manufactured by any method.
When forming a three-dimensional cross-linked resin matrix by reaction of an isocyanate compound and a compound having active hydrogen for forming a recording layer according to the present invention, a composition (X) mainly comprising an isocyanate compound immediately before molding. And a composition (Y) mainly composed of a compound having active hydrogen can be mixed and molded as it is to form a recording layer.
At this time, the compound (C) having only one functional group reactive with a hydroxyl group or an isocyanate group in the molecule may be mixed with the composition (X), or may be mixed with the composition (Y). It doesn't matter. There is no problem even if only (C) is prepared independently, (X), (Y), (C) are mixed immediately before forming the recording layer, and the molding is performed as it is.

Further, after mixing the compositions X and Y as described above, the optical recording layer material of the present invention can be applied to a support without a solvent to form a recording layer. At this time, any method can be used as a coating method. Specific examples include spraying, spin coating,
Examples thereof include a wire bar method, a dip method, an air knife coating method, a roll coating method, a blade coating method, and a doctor roll coating method.

In particular, when a thick recording layer is formed, a method of putting the optical recording layer material of the present invention into a mold and molding, or a method of coating on a release film and punching the mold is used. A recording layer can also be formed.
Alternatively, the optical recording layer material of the present invention may be mixed with a solvent to prepare a coating solution, which may be coated on a support and dried to form a recording layer. Also in this case, any method can be used as a coating method. As an example, a method similar to the above-described coating method may be mentioned.

The type of the solvent is not particularly limited, but it is usually preferable to use a solvent that has sufficient solubility for the components used, gives good coating properties, and does not attack the support.
Examples of solvents include ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; aromatic solvents such as toluene and xylene; alcohol solvents such as methanol, ethanol, and propanol; diacetone alcohol, 3-hydroxy-3-methyl Ketone alcohol solvents such as 2-butanone; ether solvents such as tetrahydrofuran and dioxane; halogen solvents such as dichloromethane and chloroform; cellosolv solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate; propylene glycol Propylene glycol solvents such as monomethyl ether and propylene glycol monoethyl ether; ester solvents such as ethyl acetate and butyl acetate; tetrafluoropropanol, octaf Perfluoroalkyl alcohol solvents such as olopentanol; highly polar solvents such as dimethylformamide, N-methylpyrrolidone and dimethyl sulfoxide; chain hydrocarbon solvents such as n-hexane and n-octane; cyclohexane and methylcyclohexane A cyclic hydrocarbon solvent; or a mixed solvent thereof.

In addition, any one of these solvents may be used alone, or two or more thereof may be used in any combination and ratio.
Moreover, there is no restriction | limiting in particular also in the usage-amount of a solvent. However, it is preferable to adjust the amount of the solvent used so that the solid content concentration of the coating solution is about 1% by weight or more and 100% by weight or less from the viewpoints of coating efficiency and handleability.

Furthermore, when the hologram recording material of the present invention has a small amount of volatile components, the hologram recording material of the present invention can be produced by molding, for example, by an injection molding method or a hot press method. In this case, when the molded body has sufficient thickness, rigidity, strength, etc., the molded body can be used as it is as the optical recording medium of the present embodiment.
Further, the recording layer made of the hologram recording material of the present invention may be produced by molding the above resin matrix into a desired shape and then impregnating it with a photoactive compound or other additives.
The optical recording medium of the present embodiment manufactured by the above-described procedure can take the form of a self-supporting slab or a disk, and is used for applications such as a three-dimensional image display device, a diffractive optical element, a large capacity memory, and a hologram drawing medium. Can be used.

[II-6. Information recording and playback method]
Both writing (recording) and reading (reproducing) information on the optical recording medium of the present embodiment are performed by light irradiation. For example, a recording method using a hologram will be described.
First, at the time of recording information, light capable of causing polymerization and concentration change of the photoactive compound is used as object light (also called recording light). In particular, in the optical recording medium of the present embodiment, in order to record information as a hologram, the object light is irradiated onto the recording layer together with the reference light so that the object light and the reference light interfere with each other in the recording layer. As a result, the interference light causes polymerization and concentration change of the photoactive compound in the recording layer, and as a result, the interference fringes cause a refractive index difference in the recording layer, and the interference recorded in the recording layer. The fringes are recorded as holograms on the recording layer.

On the other hand, when reproducing a hologram recorded on the recording layer, the recording layer is irradiated with predetermined reproduction light (usually reference light). The irradiated reproduction light is diffracted according to the interference fringes. Since the diffracted light contains the same information as the recording layer, the information recorded on the recording layer can be reproduced by reading the diffracted light with an appropriate detection means.
Note that the wavelength range of the recording light, the reproduction light, and the reference light is arbitrary depending on each application, and may be the visible light region or the ultraviolet region. Among these lights, preferred are, for example, solid lasers such as ruby, glass, Nd-YAG, Nd-YVO4; GaAs, In
Examples include diode lasers such as GaAs and GaN; gas lasers such as helium-neon, argon, krypton, excimer, and CO2; lasers excellent in monochromaticity and directivity, such as dye lasers having dyes.

Further, there is no limitation on the irradiation amount of the recording light, the reproduction light, and the reference light, and the irradiation amount is arbitrary as long as the recording and reproduction can be performed. However, if the amount is extremely small, the chemical change of the photoactive compound may be incomplete, and the heat resistance and mechanical properties of the recording layer may not be sufficiently expressed. The hologram recording material of the invention may be deteriorated. Therefore, the recording light, the reproduction light and the reference light are usually 1 mJ / cm ² or more in accordance with the composition of the hologram recording material of the present invention used for forming the recording layer, the kind of polymerization initiator, the blending amount, and the like. Irradiate within a range of 20 J / cm ² or less.
The hologram recording system includes a polarization collinear hologram recording system, a reference light incident angle multiplexing type hologram recording system, etc., and any recording is possible when the composition for forming a hologram recording layer of the present invention is used as a recording medium. Even with this method, it is possible to provide good recording quality.

[II-7. Performance]
Even when the optical recording medium of the present invention is a recording layer containing a photoactive compound having a large molecular weight for low shrinkage, mass transfer within the matrix is possible and sufficiently high recording performance is exhibited. When a photoactive compound having a large molecular weight is used, even if the glass transition temperature of the matrix is sufficiently lower than room temperature, it may still be difficult to exhibit performance, but by using the present invention, a matrix having the same glass transition temperature may be used. However, higher recording performance can be demonstrated. In addition, it is characterized by high recording performance even when the glass transition temperature of the recording layer (mainly reflecting the glass transition temperature of the matrix) is increased with the aim of durability and reliability.
Although there is no restriction | limiting in particular about the glass transition temperature of the matrix used for this invention, Usually, the thing of the glass transition temperature of minus 40 degreeC or more plus 300 degrees C or less is used. Further, in the case of using a matrix having a relatively high glass transition temperature in order to improve the durability and reliability of the medium, it is 10 ° C or higher, preferably 20 ° C or higher, more preferably 25 ° C or higher and 300 ° C or lower. Those having a glass transition temperature are used. Even when such a matrix having a high glass transition temperature is used, the high recording performance is shown because the graft chain molecules introduced into the three-dimensional crosslinked resin matrix can move relatively freely compared to the crosslinked portion. This is thought to be due to the movement and diffusion of the photoactive compound and the polymerization initiator through the portion.

II-7-1: M / # (M number)
The difference in refractive index between the recorded portion and the unrecorded portion caused by hologram recording is measured as the diffraction efficiency for each exposure energy to be input. The exposure energy to be input is measured by a multiple recording procedure. Multiplexing methods are performed by methods such as angle multiplexing in which intersecting light having a fixed angle is changed while changing the incident angle, shift multiplexing in which the position is changed without changing the incident angle, and wavelength multiplexing in which the wavelength is changed. However, angle multiplexing is simple, and it is possible to grasp the performance of the material and each component.

  The angle at which the sample is moved with respect to the optical axis (the angle formed by the two light beams, that is, the bisector of the inner angle at the point where the incident light from the mirrors M1 and M2 in FIG. 1 intersects) and the normal from the sample is −20 degrees. If recording is performed in increments of 1 degree from 20 degrees to 41 degrees, 41 multiplexing is possible if recording is performed in increments of 0.5 degrees from -30 degrees to 30 degrees. There are two expressions of diffraction efficiency: the ratio of incident light to diffracted light (also referred to as external diffraction efficiency), the sum of transmitted light and diffracted light, and the ratio of diffracted light (also referred to as internal diffraction efficiency). In the present invention, the reflection efficiency of the sample surface and the diffusion inside the sample can be ignored, and the internal diffraction efficiency that asks the recording performance of the material is defined as the diffraction efficiency. If the diffraction efficiency for each recording is too high, the monomer is consumed when the number of recordings is young, and multiple recording cannot be performed. Further, if the diffraction efficiency for each recording is too small, the monomer remains, and in any case, there is a possibility of underestimating M / #. Therefore, by determining the diffraction efficiency of one recording to about several percent and obtaining M / # obtained by recording with as much multiplicity as possible, it can be an appropriate multiplex recording standard.

Since M / # (M number), which is the sum of diffraction efficiencies obtained by performing multiple recording, is a numerical value that serves as a guide for recording capacity, it can be said that a larger value indicates better performance as a medium.
Generally, the higher the content of the photoactive compound, the higher the diffraction efficiency and the M / #.
M / # of the recording layer of the hologram recording medium of the present embodiment is usually 10 or more, preferably 12 or more, particularly preferably 15 or more when evaluated as a recording layer having a thickness of 500 μm.

As described above, the larger the value of M / #, the better, and it is not necessary to set a clear upper limit. In general, the larger the M / #, the higher the recording density. As described above, M / # (M number) of the recording layer according to the present invention is a value evaluated for a recording layer having a thickness of 500 μm.
That is, except that the recording layer provided for a certain hologram recording medium has a thickness of 500 μm, an evaluation medium shown in the section of an example described later is manufactured, and this evaluation medium is M / # ( M number) 10 or more, especially 12 or more, especially 15 or more can be said to be a hologram recording medium suitable for the present invention.

This M / # (M number) is measured by the method shown in the section of Examples described later.
Alternatively, in the case of a recording medium whose recording layer film thickness is not 500 μm, the M / # is evaluated by the same method for the medium, and the result converted to a value at the recording layer film thickness of 500 μm is 10 or more, particularly 12 or more. In particular, a recording medium having a value of 15 or more can be said to be a hologram recording medium suitable for the present invention.

M / # generally tends to increase as the recording layer thickness increases.
When the recording layer thickness is 200 to 700 μm, the recording layer thickness and M / # show a substantially proportional relationship. Therefore, the result of evaluating a medium having a recording layer within this thickness range is corrected in proportion. It becomes possible to contrast.
On the other hand, in the range where the recording layer film thickness exceeds 1000 μm, the increase in M / # with respect to the recording layer film thickness becomes gradual, and it is difficult to compare by simply correcting the film thickness by proportional calculation. In this case, a recording layer composition that is known to be in the above numerical range at a thickness of 500 μm is selected, and a medium is manufactured with a thickness of 500 μm and a thickness corresponding to the recording layer thickness of the actual medium to be evaluated. Based on the correlation between the two, the M / # value of the actual medium can be converted into the M / # value at a thickness of 500 μm.
Further, since layers other than the recording layer constituting the hologram recording medium, such as the substrate, the protective layer, and the reflective layer, do not greatly affect the value of M / #, even for media having different layer configurations other than the recording layer, M / # Is possible.

II-7-2: Sensitivity In the present invention, the sensitivity represents an average sensitivity up to 80% of the maximum M / # indicated by the sample, and is calculated as follows.
Sensitivity = (0.8 × (M / #)) / (I × ts × L)
Here, I is the incident light intensity (mW / cm ² ), ts is the total exposure time (seconds) until M / # reaches 80%, and L is the recording layer thickness (cm).

The sensitivity of the recording layer of the hologram recording medium of the present embodiment is usually from 0.10 cm / mJ to 30 cm / mJ, more preferably from 0.15 cm / mJ to 10 cm / mJ.
Since the value is normalized by the recording layer thickness, the dependency of the sensitivity on the recording layer thickness is not explicitly shown. On the other hand, the sensitivity value is a value that can vary depending on the light transmittance of the recording layer, the initiator type, the initiator amount, the photoactive compound, the glass transition temperature of the matrix, the elastic modulus, the presence or absence of additives, the type, and various other factors. is there.

II-7-3: Light Transmittance Measurement of light transmittance is an important index for recording with light. If the sample or the recording layer is thick, the light is absorbed and scattered inside and the light intensity is insufficient, so that the recording performance may be inferior. It can be said that the high light transmittance before recording is a good performance in recording to a deeper recording layer and improving the capacity.

Similarly, a high light transmittance even after recording can be said to be a good performance because errors can be reduced in recording reproduction. After recording, the photopolymerization initiator is chemically changed by light irradiation, and the absorption intensity greatly changes at the wavelength of the recording light. Therefore, the transmittance is measured before and after recording.
The light used for the measurement of the light transmittance is preferably at or near the recording wavelength, but the chemical change of the photopolymerization initiator in the recording layer before recording becomes noticeable, and the transmittance changes with time. Therefore, it must be measured in a sufficiently short time. If you pay attention to this point, you can measure without problems and obtain reliable and reproducible measurement values. A sufficiently short time is about 1 second or less. After recording, the photopolymerization initiator is not consumed and does not cause a temporal change, so the measurement time is not a concern.

  In general, the light transmittance is preferably closer to 100%, but is preferably approximately 60% or more, particularly preferably 80% or more. In the hologram recording medium of the present embodiment, when evaluated with a recording layer thickness of 500 μm, the light transmittance before recording is usually 60% or more, preferably 70% or more, and the light transmittance after recording is usually 60%. Above, preferably 70% or more can be achieved. In addition, this light transmittance is specifically measured by the method described in the item of the below-mentioned Example.

Further, in the case of a recording medium whose recording layer thickness is not 500 μm, the light transmittance was evaluated by the same method for the medium, and the result converted into a value at a recording layer thickness of 500 μm was a light transmittance of 60% or more, If it is preferably 70% or more, it can be said to be a hologram recording medium suitable for the present invention.
The light transmittance is generally affected by the recording layer thickness, and the light transmittance tends to decrease as the recording layer thickness increases, except when the light transmittance is 100%. When the recording layer thickness is 200 to 700 μm, the recording layer thickness and the light transmittance are almost inversely proportional. Therefore, the result of evaluating a medium having a recording layer within this thickness range should be corrected in inverse proportion. The comparison becomes possible.

On the other hand, in the range where the recording layer thickness exceeds 1000 μm, except for the case where the decrease in light transmittance with respect to the recording layer thickness is 100%, the recording layer thickness decreases more rapidly than the inverse proportion in the recording layer thickness 200 to 700 μm. Conversion is difficult.
The transparent layer other than the recording layer constituting the hologram recording medium, such as the substrate and the protective layer, has a sufficiently large light transmittance with respect to the normal recording layer, and the value of the light transmittance as the medium is substantially recorded. It can be regarded as the transmittance of the layer. In the case of a recording medium having an opaque layer such as a reflective layer, the thickness of the reflective layer is sufficiently thinner than 1 or less than that of the recording layer or the substrate, so that the influence of the light transmittance on the medium can be ignored. In this way, it is possible to directly compare the light transmittance even for media having different layer configurations other than the recording layer.

EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.
[Example 1]
Preparation of composition for forming optical recording layer 10.57 g of hexamethylene diisocyanate, 0.928 g of N-vinylcarbazole and 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO: manufactured by Ciba Specialty) 0.046 g was weighed and stirred until each component was dissolved.

  Next, polyoxypropylene triol having a molecular weight of about 1000 (Sanyo Kasei Co., Ltd., GP-1000) 11.66 g, trimethylolpropane 3.89 g, and polystyrene standard number average molecular weight of about 1,000 in a sample bottle 2 are polypropylene glycol monobutyl ether. 3.89 g and dioctyltin dilaurate 0.007 g were weighed and stirred until each component was dissolved.

Thereafter, the sample bottle 2 was deaerated under vacuum for 3 hours, and then the liquids of the sample bottles 1 and 2 were mixed and stirred and mixed, and further deaerated under vacuum for several minutes.
・ Production of the medium Subsequently, the vacuum degassed liquid was poured onto the slide glass on which a 500 μm thick Teflon (registered trademark) sheet as a spacer was placed on the two ends, and the slide glass was put on the slide glass, and then the clip. Then, the periphery was fixed and heated at 60 ° C. for 15 hours to produce a measurement hologram recording medium. As shown in FIG. 2, the measurement hologram recording medium has a recording layer 22 having a thickness of 500 μm formed between slide glasses as cover layers 21 and 23.
The sample obtained in this way was evaluated for hologram recording performance. The conditions for evaluation are as follows.

[Hologram recording]
Using the obtained hologram recording medium, hologram recording was performed according to the procedure described below.
Using a semiconductor laser with a wavelength of 405 nm, two-beam plane wave hologram recording was performed using an exposure apparatus as shown in FIG. 1 at an exposure power density of 6.0 mW / cm ² per beam. The medium is recorded 61 times in the same place every other from -30 degrees to 30 degrees, and the total of the square roots of the diffraction efficiency at that time is defined as M / # (M number). The light transmittance at the recording wavelength was measured before and after the recording. Details will be described below.

FIG. 1A is a configuration diagram showing an outline of the apparatus used for hologram recording, FIG. 1B is a configuration diagram showing the surface of the LED unit, and FIG. It is a block diagram which shows the arrangement | sequence of LED.
In FIG. 1, S represents a sample of the hologram recording medium, M1 to M3 all represent mirrors, PBS represents a polarizing beam splitter, and L1 represents a laser light source for recording light that emits light having a wavelength of 405 nm (light near 405 nm). (L1 in FIG. 1)), L2 represents a laser light source for reproducing light that emits light having a wavelength of 633 nm, and PD1 and PD2 represent photodetectors. Reference numeral 1 denotes an LED unit, 2 denotes an arm, and 3 denotes a support.

  In the case of normal recording and reproduction, the LED unit is in the position of the solid line, and in the case of uniform exposure, the arm 2 to which the support column 3 is rotated and the LED of the LED unit 1 is the sample S as shown by the broken line. After moving to the front side of the recording part, the LED lights up for a certain time. As shown in FIG. 1C, the LEDs 1B are arranged on the LED unit surface 1A like dice 5 as dice. A power source is connected to the light sources L1 and L2, the photodetectors PD1 and PD2, and the LED unit 1.

  As shown in FIG. 1, 405 nm light was split by a polarizing beam splitter (“PBS” in the figure) and crossed on the recording surface so that the angle formed by the two beams was 50.00 degrees. At this time, the bisector of the angle formed by the two beams is perpendicular to the recording surface, and the vibration planes of the electric field vectors of the two beams obtained by the division are two intersecting lines. Irradiation was performed so as to be perpendicular to the plane including the beam.

  After hologram recording, using a He-Ne laser that can obtain 633 nm light (Melesgrio V05-LHP151: “L2” in the figure), the light is irradiated at an angle of 30.19 degrees with respect to the recording surface. Whether the hologram recording is correctly performed by detecting the diffracted light using a power meter and a detector (Newport 2930-C, 918-SL: “PD1” and “PD2” in the figure). It was judged. The diffraction efficiency of a hologram is given by the ratio of the intensity of diffracted light to the sum of transmitted light intensity and diffracted light intensity.

<Measurement of M / #>
The angle at which the sample is moved relative to the optical axis (the angle between the two light fluxes, that is, the angle between the bisector of the internal angle at the point where the incident light from the mirrors M1 and M2 in FIG. 1 intersects) and the normal from the sample is from 30 degrees. 61 multiplex recording was performed in increments of 1 degree up to 30 degrees, and the sum of the obtained square roots of diffraction efficiency over the entire multiplex recording area was defined as M / #.

  Specifically, for each example, using one of a plurality of optical recording media prepared first, the angle between the bisector of the inner angle at the point where the two light beams intersect and the normal of the medium is zero. The two beams, that is, the incident light 405 nm from the mirrors M1 and M2 in FIG. 1 are irradiated until the diffraction efficiency becomes constant, and the minimum energy that becomes constant is measured (at this time, the evaluation of the diffraction efficiency is from the mirror M3). Using light 633 nm).

  Next, with respect to another medium, multiple recording is performed using the previously obtained minimum energy value as a guide for the total irradiation energy in 61 multiple recording. At this time, the irradiation energy is appropriately adjusted according to the number of times of recording, and a diffraction efficiency of several percent for each recording is maintained. After 61 times of multiple recording, the light (405 nm) from the mirror M1 in FIG. 1 is subsequently irradiated, the diffraction efficiency from an angle of −30 to 30 degrees is measured, and the sum of the square roots of the diffraction efficiency at each angle (M / #) Ask for.

  While changing the sample, performing multiple evaluations with different irradiation energy conditions such as increase / decrease in irradiation energy at the beginning of recording and increase / decrease in total irradiation energy, while maintaining diffraction efficiency of several percent or more for each recording, 61 The search was made for a condition in which the contained monomer was almost completely consumed by the first recording (M / # almost reached equilibrium by the 61st recording), and the maximum value was obtained as M / #. The maximum value obtained was defined as M / # of the medium.

<Sensitivity>
Further, the sensitivity of the sample represents an average sensitivity until the maximum M / # indicated by the sample reaches 80% in the M / # measurement, and is calculated as follows.
Sensitivity = (0.8 × (M / #)) / (I × ts × L)
Here, I is the incident light intensity (mW / cm ² ), ts is the total exposure time (seconds) until M / # reaches 80%, and L is the recording layer thickness (cm).

<Light transmittance before recording, light transmittance after recording>
For light transmittance, after measuring the light intensity in the absence of any sample, place the sample vertically in the optical path and measure the light intensity again in a short time so that no chemical change occurs. The ratio was defined as light transmittance. In the case after recording, the sample was measured by placing the portion of the sample recorded at an angle perpendicular to the optical path and at which diffraction does not occur so that light can pass through. The wavelength was 405 nm, the same wavelength as the recording, the intensity was 6 mW / cm ² , and the recording layer thickness was 500 μm.

[Viscoelasticity evaluation of recording layer]
<Glass transition temperature>
The glass transition temperature of the obtained recording layer was measured as follows. That is, the recording layer was cut into a strip having a width of about 1 cm and a length of about 3 cm, and used as a measurement sample, which was measured with a dynamic viscoelasticity measuring apparatus (EXTAR DMS-6100 manufactured by SII Nano Technologies). The temperature rise rate was measured at a temperature of −100 ° C. to 120 ° C. at a rate of 2 ° C. per minute and a measurement frequency of 10 Hz. The storage elastic modulus E ′, loss elastic modulus E ″ and loss tangent (E ″ / E) '= Tan δ) was calculated. Here, the peak giving the maximum value of tan δ was defined as the main dispersion peak, and the temperature indicating the maximum value was defined as the glass transition temperature of the sample.

[Example 2]
A composition for forming an optical recording layer was prepared in the same manner as in Example 1, except that 10.57 g of hexamethylene diisocyanate was used and 0.928 g of bisdibenzothiophenylphenyl acrylate was used instead of 0.928 g of N-vinylcarbazole. did.
For the obtained composition liquid, a hologram recording medium was prepared by the same procedure as in Example 1, and the hologram recording performance was measured.

[Comparative Example 1]
Hexamethylene diisocyanate is 10.98 g, polyoxypropylene triol having a molecular weight of about 1000 (manufactured by Sanyo Chemical Co., Ltd., GP-1000) is 15.21 g, and polypropylene glycol monobutyl ether having a polystyrene standard number average molecular weight of about 1000 is not added. A composition for forming an optical recording layer was prepared in the same manner as in Example 1 except that.

For the obtained composition liquid, a hologram recording medium was prepared by the same procedure as in Example 1, and the hologram recording performance was measured.
[Comparative Example 2]
11.58 g of hexamethylene diisocyanate, 11.19 g of polyoxypropylene triol having a molecular weight of about 1000 (manufactured by Sanyo Chemical Co., Ltd., GP-1000), 3.89 g of polypropylene glycol monobutyl ether having a polystyrene standard number average molecular weight of about 1000 Instead, a composition for forming an optical recording layer was prepared in the same manner as in Example 1 except that 3.73 g of tripropylene glycol monomethyl ether (molecular weight: about 206) was used.

  For the obtained composition liquid, a hologram recording medium was prepared by the same procedure as in Example 1, and the hologram recording performance was measured.

In both Examples 1 and 2 using a three-dimensional cross-linked resin matrix having a graft chain having a polystyrene standard number average molecular weight of 300 or more, the glass transition temperature of the recording layer is not less than room temperature. Good value was shown.
On the other hand, in Comparative Example 1 using a three-dimensional cross-linked resin matrix having no graft chain, the glass transition temperature of the recording layer is lower than those in Examples 1 and 2, and the sensitivity of hologram recording is low despite being near room temperature. Obviously it was low. Further, in Comparative Example 2 using a three-dimensional cross-linked resin matrix having a graft chain having a molecular weight of slightly over 200, the glass transition temperature of the recording layer was even lower than in Examples 1 and 2, although it was below room temperature, The hologram recording sensitivity was clearly below Examples 1 and 2.

  The recording layer for an optical recording medium of the present invention is suitably used for various media related to optical recording, particularly a hologram optical recording medium.

1 LED unit
1A LED unit surface
1B LED
2 arms
3 props
S sample
M1, M2, M3 mirror
PBS Polarizing beam splitter
L1 Laser light source for recording light
L2 Laser light source for reproduction light
PD1, PD2 Photo detector
21 Cover layer
22 Recording layer
23 Cover layer

Claims (6)

An optical recording layer forming composition comprising a three-dimensional crosslinked resin matrix-forming component, the following compound A, a photoactive compound, and a photopolymerization initiator.
Compound A: a functional group capable of reacting with the three-dimensional cross-linking resin matrix, a hydroxyl group, an amino group, an isocyanate group, a carboxyl group, having only one mercapto group or an epoxy group, molecular weight 5 00 or more, or a number average molecular weight 5 00 or more, A compound having a molecular weight of 100,000 or less or a number average molecular weight of 100,000 or less . 2. The composition for forming an optical recording layer according to claim 1, wherein the compound A is a monofunctional alcohol. The composition for forming an optical recording layer according to claim 1 or 2 , wherein the content of compound A is 1% by weight or more based on the whole composition. Three-dimensional crosslinked matrix forming component, an isocyanate group in a molecule, a hydroxyl group, an epoxy group, compounds containing functional groups of two or more selected from the group consisting of amino and carboxyl groups, either of claims 1-3 1 The composition for forming an optical recording layer described in the item. The molecular weight of the photoactive compound is 200 or more, an optical recording layer forming composition according to any one of claims 1-4. Using an optical recording layer forming composition according to any one of claims 1 to 5 recording layer, the optical recording medium.

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