JP2008090027A - Hologram recording material and hologram recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram recording material and a recording medium that achieve high refractive index change, flexibility, high sensitivity, low scattering, environmental resistance, durability, small dimensional changes small (low shrinkage) and high multiplicity. <P>SOLUTION: The hologram recording material comprises a metal oxide matrix and a photopolymerizable compound, and the metal oxide matrix is formed of a matrix forming material, containing at least a cyclic ether group-containing metal alkoxide compound (I) expressed by (R<SB>E</SB>)mM<SB>I</SB>(OR<SB>11</SB>)n or its polymers, wherein the formula, R<SB>E</SB>represents a cyclic ether group-containing organic group, R<SB>11</SB>represents an alkyl group and M<SB>I</SB>represents metal; and a metal alkoxide compound (II) that does not contain cyclic ether group expressed by (R<SB>22</SB>)jM<SB>II</SB>(OR<SB>21</SB>)k or its polymers, wherein R<SB>22</SB>represents an alkyl group or an aryl group, R<SB>21</SB>represents an alkyl group and M<SB>II</SB>represents a metal. The hologram recording medium 11 has a hologram recording layer 21 comprising the hologram recording material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hologram recording material suitable for volume hologram recording, and a hologram recording medium having a hologram recording layer made of the hologram recording material. In particular, the present invention relates to a hologram recording material that is suitable for recording / reproduction using not only green laser light but also blue laser light, and a hologram recording medium having a hologram recording layer made of the hologram recording material.

  Research and development of holographic memory is underway as a recording technology that enables high-capacity and high-speed transfer. O plus E, Vol. 25, No. 4, 385-390 (2003) describes the basic structure of holographic memory and future prospects.

  Properties required for the hologram recording material include high refractive index change, high sensitivity, low scattering, environmental resistance, durability, low dimensional change, and high multiplicity during recording. Until now, various reports have been made on holographic memory recording using a green laser as follows.

  As a hologram recording material, a photopolymer material containing an organic binder polymer and a photopolymerizable monomer as main components is known. However, the photopolymer material has problems in environmental resistance, durability, and the like. In order to solve the problems of the photopolymer material, an organic-inorganic hybrid material mainly composed of an inorganic matrix and a photopolymerizable monomer has attracted attention and has been studied. The inorganic matrix is excellent in environmental resistance and durability.

  For example, Japanese Patent No. 2953200 discloses an optical recording film containing a photopolymerizable monomer or oligomer and a photopolymerization initiator in an inorganic substance network film. It is also disclosed to modify the inorganic network organically to improve the brittleness of the inorganic network film. However, the compatibility between the inorganic substance network and the photopolymerizable monomer or oligomer is not good. Therefore, it is difficult to obtain a uniform film. Specifically disclosed in the publication is that a photosensitive layer ([0058]) having a thickness of about 10 μm was exposed with an argon laser of 514.5 nm ([0059]).

  Japanese Patent Application Laid-Open No. 11-344917 discloses an optical recording medium containing a photoactive monomer in an organic-inorganic hybrid matrix. The organic-inorganic hybrid matrix has an alkyl group (methyl group) or an aryl group (phenyl group) as a metal element. However, the introduction of methyl groups cannot improve the compatibility between the hybrid matrix and the photoactive monomer. The introduction of the phenyl group improves the compatibility over the introduction of the methyl group. However, the introduction of the phenyl group reduces the curing rate of the hybrid matrix precursor (the same publication [0015]). Specifically disclosed in the publication is that a hologram recording layer having a thickness of 100 μm is recorded by a YAG laser having a wavelength of 532 nm (Example 3, [0031]).

  Japanese Patent Laid-Open No. 2002-236439 discloses an organic-inorganic obtained by copolymerizing an organometallic compound containing an ethylenically unsaturated double bond as a main chain component and an organic monomer having an ethylenically unsaturated double bond. A hologram recording material including a matrix composed of a hybrid polymer and / or a hydrolyzed polycondensate thereof, a photopolymerizable compound, and a photopolymerization initiator is disclosed. By introducing a large organic backbone component into the matrix material, the compatibility between the matrix and the photopolymerizable compound is improved. However, the introduction of a large organic main chain component will result in the presence of a binary structure of the organic main chain and inorganic network in the matrix material and may not show a single behavior as a matrix during recording. It is conceivable that non-uniform recording occurs. Further, when the ratio of the organic main chain component in the matrix is large, the same problem as in the photopolymer material using the organic binder polymer occurs. Specifically disclosed in the publication is that a hologram recording material layer ([0080]) having a thickness of 20 μm is exposed by an argon laser of 514.5 nm ([0081]).

  In order to solve the problems of the hologram recording material disclosed in each of the above publications, JP-A-2005-321684 has at least two kinds of metals (Si, Ti), oxygen, and an aromatic group, And an organometallic compound (organic-inorganic hybrid matrix) having an organometallic unit in which two aromatic groups are directly bonded to one metal (Si), and a photopolymerizable compound (organic monomer). A hologram recording material is disclosed. In Example 1 (particularly [0074] to [0078]) of the same publication, a hologram recording medium having a layer of the hologram recording material having a thickness of 100 μm has high transmission in recording with an Nd: YAG laser (532 nm). It has been disclosed that high index, high refractive index change, low scattering, and high multiplicity have been obtained.

O plus E, Vol. 25, No. 4, 385-390 (2003) Japanese Patent No. 2953200 JP-A-11-344917 JP 2002-236439 A JP-A-2005-321684

  None of the above publications discloses holographic memory recording using a green laser, but does not disclose holographic memory recording using a blue laser.

  In the hologram recording material, it is difficult to balance the mechanical strength of the organic-inorganic hybrid matrix and the mobility of the organic monomer.

  That is, in order to suppress shrinkage due to organic monomer polymerization during recording exposure, the mechanical strength of the matrix must be increased as much as possible. Further, when the diffusion of each component after recording (polymer generated by polymerization of monomer, hydrolysis product) proceeds gradually, the storage stability of the recorded signal deteriorates. In order to suppress the diffusion of each component after recording, the mechanical strength of the matrix must be increased as much as possible. Suppression of shrinkage at the time of recording exposure and suppression of diffusion of each component after recording are more required in the case of recording / reproducing with blue laser light than in the case of recording / reproducing with green laser light.

  On the other hand, in order to ensure a sufficient degree of modulation of the recording signal, the organic monomer quickly diffuses into the recording exposed portion, and the organic monomer (or polymer thereof) has a sufficient concentration gradient between the exposed portion and the unexposed portion. Must have. A decrease in the mobility of the organic monomer causes a decrease in recording sensitivity and dynamic range. In order for organic monomers to diffuse quickly (ie high mobility), the matrix must have a somewhat porous structure, which contradicts the requirement for high strength of the matrix.

  Thus, in the organic-inorganic hybrid matrix by the sol-gel method, the mechanical strength of the matrix and the mobility of the organic monomer are in a trade-off relationship.

  The object of the present invention is to provide high refractive index change, flexibility, high sensitivity, low scattering, environmental resistance, durability, low dimensional change (low shrinkage) not only in green laser but also in holographic memory recording using blue laser. And a hologram recording material and a hologram recording medium suitable for volume hologram recording, in which high multiplicity is achieved.

  As a result of intensive studies, the present inventors have not only determined the cross-linking density between metals (cross-linking by metal-oxygen-metal bonds) by sol-gel reaction (that is, hydrolysis / polycondensation) of metal alkoxide compounds, but also cyclicity. High mechanical strength of the organic-inorganic hybrid matrix can be obtained while maintaining the flexibility to achieve high mobility of the monomer at the micro level by utilizing the crosslinking density improvement by the coupling reaction of the ether group. I found.

The present invention includes the following inventions.
(1) A hologram recording material comprising a metal oxide matrix and a photopolymerizable compound,
Metal oxide matrix
Formula (I):
(R _E ) m M _I (OR ₁₁ ) n (I)
(Here, R _E represents a cyclic ether group-containing organic group, R ₁₁ represents an alkyl group, M _I represents a metal, m represents 1, 2 or 3, n represents an integer of 1 or more, However, m + n is the valence number of metal M _I.)
A cyclic ether group-containing metal alkoxide compound (I) represented by
General formula (II):
(R ₂₂ ) j M _II (OR ₂₁ ) k (II)
(Here, R ₂₂ represents an alkyl group or an aryl group, R ₂₁ represents an alkyl group, M _II represents a metal, j represents 0, 1, 2, or 3, and k represents an integer of 1 or more.) , however, j + k is the valence number of metal M _II.)
A hologram recording material formed from a matrix-forming material containing at least the metal alkoxide compound (II) represented by the formula (II) or a multimer thereof. The metal alkoxide compound (II) does not contain a cyclic ether group.

  (2) The hologram recording material according to the above (1), wherein the cyclic ether group of the metal alkoxide compound (I) is an epoxy group or an oxetanyl group.

  (3) The hologram recording material according to the above (1) or (2), wherein the matrix forming material further comprises at least one selected from the group consisting of a polyfunctional epoxy compound and a polyfunctional oxetanyl compound.

(4) metal M _I in the cyclic ether group-containing metal alkoxide compound (I) is a Si, hologram recording material according to any one of (1) to (3).

(5) the metal alkoxide compound (II) is different from at least two are used with metal M _II, 1 kind of metal M _II is a Si, other metals M _II other than Si is, Ti, Ta, Zr The hologram recording material according to any one of (1) to (4), selected from the group consisting of: Ge, Sn, Al, and Zn.

  (6) The hologram recording material according to any one of (1) to (5), further comprising a photopolymerization initiator. The hologram recording material further contains a photoradical initiator when the photopolymerizable compound is a radical polymerizable compound.

  (7) A hologram recording medium having a hologram recording layer made of the hologram recording material according to any one of (1) to (6) above.

  (8) The hologram recording medium according to (7), wherein the hologram recording layer has a thickness of at least 100 μm.

  (9) The hologram recording medium according to (7) or (8), which is recorded / reproduced by laser light having a wavelength of 350 to 450 nm.

(10) General formula (I):
(R _E ) m M _I (OR ₁₁ ) n (I)
(Here, R _E represents a cyclic ether group-containing organic group, R ₁₁ represents an alkyl group, M _I represents a metal, m represents 1, 2 or 3, n represents an integer of 1 or more, However, m + n is the valence number of metal M _I.)
A cyclic ether group-containing metal alkoxide compound (I) represented by
General formula (II):
(R ₂₂ ) j M _II (OR ₂₁ ) k (II)
(Here, R ₂₂ represents an alkyl group or an aryl group, R ₂₁ represents an alkyl group, M _II represents a metal, j represents 0, 1, 2, or 3, and k represents an integer of 1 or more.) , however, j + k is the valence number of metal M _II.)
A composition for forming a hologram recording matrix material comprising at least a metal alkoxide compound (II) not containing a cyclic ether group represented by the formula (II) or a multimer thereof.

  (11) The composition for forming a hologram recording matrix material according to the above (10), wherein the cyclic ether group of the metal alkoxide compound (I) is an epoxy group or an oxetanyl group.

  (12) The composition for forming a hologram recording matrix material according to (11) or (12), further comprising at least one selected from the group consisting of a polyfunctional epoxy compound and a polyfunctional oxetanyl compound.

(13) General formula (I):
(R _E ) m M _I (OR ₁₁ ) n (I)
(Here, R _E represents a cyclic ether group-containing organic group, R ₁₁ represents an alkyl group, M _I represents a metal, m represents 1, 2 or 3, n represents an integer of 1 or more, However, m + n is the valence number of metal M _I.)
A cyclic ether group-containing metal alkoxide compound (I) represented by
General formula (II):
(R ₂₂ ) j M _II (OR ₂₁ ) k (II)
(Here, R ₂₂ represents an alkyl group or an aryl group, R ₂₁ represents an alkyl group, M _II represents a metal, j represents 0, 1, 2, or 3, and k represents an integer of 1 or more.) , however, j + k is the valence number of metal M _II.)
A step of mixing a metal alkoxide compound (II) represented by
Hydrolyzing the mixed alkoxide compound and simultaneously or subsequently subjecting a cyclic ether group to a cation coupling reaction to obtain a precursor of a metal oxide matrix;
Before the hydrolysis, when hydrolyzing, or after hydrolysis, mixing the photopolymerizable compound;
A step of proceeding a polycondensation reaction of a metal oxide precursor mixed with a photopolymerizable compound;
A method for producing a hologram recording material comprising:

  (14) The production of the hologram recording material according to the above (13), wherein at least one selected from the group consisting of a polyfunctional epoxy compound and a polyfunctional oxetanyl compound is added before the cation coupling reaction of the cyclic ether group. Method.

  According to the present invention, the metal oxide (organic-inorganic hybrid) matrix is formed using a metal alkoxide compound containing a cyclic ether group and a metal alkoxide compound not containing a cyclic ether group. Therefore, the mechanical strength of the matrix is determined not only by the crosslink density between metals (crosslinking by metal-oxygen-metal bonds) by the sol-gel reaction (that is, hydrolysis / polycondensation) of the metal alkoxide compound, but also by cyclic ether groups. It is obtained by improving the crosslinking density by a coupling reaction. Excess bridging density between metal atoms via oxygen atoms is not necessary. Therefore, the matrix in the present invention has a high crosslink density and excellent mechanical strength, and also has flexibility to achieve high mobility of the monomer at the micro level.

  Thus, in the hologram recording material of the present invention, since the matrix has a high mechanical strength, the shrinkage during recording exposure is very small, the storage stability is excellent, and the matrix is a monomer at the micro level. Therefore, it has a high recording sensitivity and a high dynamic range.

  By using the hologram recording material of the present invention, a hologram recording medium suitable for recording / reproducing by blue laser light as well as green laser light is provided.

  The hologram recording material of the present invention is a composition comprising a metal oxide (organic-inorganic hybrid) matrix and a photopolymerizable compound (monomer), wherein the metal oxide matrix comprises a cyclic ether group-containing metal alkoxide compound (I). ) And a metal alkoxide compound (II) not containing a cyclic ether group, and optionally a matrix-forming material containing a polyvalent epoxy compound, by a sol-gel reaction and a cyclic ether group coupling reaction. It is a gel or sol. The metal oxide functions as a matrix or a dispersion medium for the photopolymerizable compound in the hologram recording material layer. That is, the liquid phase photopolymerizable compound is uniformly dispersed in the gel-like or sol-like metal oxide matrix with good compatibility.

  When the hologram recording material layer is irradiated with coherent light, the photopolymerizable organic compound (monomer) undergoes a polymerization reaction in the exposed area and polymerizes, and the photopolymerizable organic compound diffuses from the unexposed area to the exposed area. It moves, and further, the exposed area is polymerized. As a result, a polymer-rich region and a polymer-poor region generated from the photopolymerizable organic compound are formed according to the light intensity distribution. At this time, the metal oxide moves from the polymer-rich region to the polymer-poor region, the polymer-rich region becomes the metal oxide-poor region, and the polymer-poor region is the metal oxide region. There are many areas. In this way, a region having a large amount of the polymer and a region having a large amount of the metal oxide are formed by exposure, and when there is a refractive index difference between the polymer and the metal oxide, the region is refracted according to the light intensity distribution. The rate change is recorded.

  In order to obtain better recording characteristics in the hologram recording material, it is necessary that the difference between the refractive index of the polymer generated from the photopolymerizable compound and the refractive index of the metal oxide is large. As for the refractive indexes of both the polymer and the metal oxide, either one may be designed to be higher and the other may be designed to be lower.

  In designing the hologram recording material, when the metal oxide has a lower refractive index than the polymer produced from the photopolymerizable compound, Si is preferably used in a relatively large content. On the other hand, when the metal oxide has a higher refractive index than the polymer produced from the photopolymerizable compound, Ti, Ta, Zr, etc. may be used in a relatively large content ratio.

The cyclic ether group-containing metal alkoxide compound (I) has the general formula (I):
(R _E ) m M _I (OR ₁₁ ) n (I)
It is represented by R _E represents a cyclic ether group-containing organic group, R ₁₁ represents an alkyl group, M _I represents a metal, m represents 1, 2 or 3, n represents an integer of 1 or more, provided that m + n is is the valence number of metal M _I. R _E may be different _depending on m, and R ₁₁ may be different depending on n. Here, the cyclic ether group is preferably selected from an epoxy group and an oxetanyl group.

Examples of the cyclic ether group-containing organic group represented by R _E include an alkyl group containing an epoxy group or an oxetanyl group, an aryl group containing an epoxy group or an oxetanyl group, and the like. Specifically, without limitation, 3,4-epoxycyclohexylmethyl group, 2- (3,4-epoxycyclohexyl) ethyl group, 3-glycidoxypropyl group, 3- (3-ethyl-3- Oxetanyl) methoxypropyl group and the like.

The alkyl group represented by R ₁₁ is usually a lower alkyl group having about 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a sec-butyl group. The alkyl group may have a substituent.

Examples of the metal atom represented by M _I include Si, Ti, Ta, Zr, Ge, Sn, Al, and Zn. Of these, Si is preferably used from the viewpoint of easy availability of the metal alkoxide compound (I). m represents 1, 2 or 3, n represents an integer of 1 or more, provided that, m + n is the valence number of metal M _I. Metal M _I is Si, Ti, in the case of Zr is, m + n is 4, in the case of Ta is, m + n is 5. Further, m is usually 1, but may be 2 or 3.

Specific examples of the metal alkoxide compound (I) in which the metal M _I is Si include 3,4-epoxycyclohexylmethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4 -Epoxycyclohexyl) ethyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-ethyl-3- (triethoxysilyl) Propyloxy) methyl oxetane and the like.

  As the cyclic ether group-containing metal alkoxide compound (I), only one type may be used, or two or more types may be used. Further, a multimer of metal alkoxide compound (I) (corresponding to a partial hydrolysis-condensation product of metal alkoxide compound (I)) may be used. The metal alkoxide compound (I) and the multimer of the metal alkoxide compound (I) may be used in combination.

The metal alkoxide compound (II) containing no cyclic ether group has the general formula (II):
(R ₂₂ ) j M _II (OR ₂₁ ) k (II)
It is represented by R ₂₂ represents an alkyl group or an aryl group, R ₂₁ represents an alkyl group, M _II represents a metal, j represents 0, 1, 2, or 3, k represents an integer of 1 or more, provided that j + k is the valence number of metal M _II. R ₂₂ may be different depending on j, and R ₂₁ may be different depending on k.

The alkyl group represented by R ₂₂ is usually a lower alkyl group having about 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a sec-butyl group. The aryl group represented by R ₂₂ includes a phenyl group. The alkyl group and aryl group may have a substituent other than the cyclic ether group.

The alkyl group represented by R ₂₁ is usually a lower alkyl group having about 1 to 4 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a sec-butyl group. The alkyl group may have a substituent.

Examples of the metal atom represented by M _II include Si, Ti, Ta, Zr, Ge, Sn, Al, and Zn. In the present invention, it is preferable to use at least two different kinds of metal alkoxide compound (II) of the metal M _II, 1 kind of metal M _II is a Si, other metals M other than Si is, Ti, It is preferably selected from the group consisting of Ta, Zr, Ge, Sn, Al and Zn. Examples of combinations of two kinds of metals include Si and Ti, Si and Ta, and Si and Zr. Of course, a combination of three metals may be used. By including two or more kinds of metals as constituent elements, it is easy to control characteristics such as the refractive index of the metal oxide matrix, which is preferable in designing the recording material.

Specific examples of the alkoxide compound of a metal M _II is Si (II) is, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane (above, j = 0, k = 4 ), methyltrimethoxysilane, ethyltrimethoxysilane Silane, propyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyl Triethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane (j = 1, k = 3), dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane And j = 2, k = 2) and the like.

  Among these silicon compounds, preferred examples include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, methyltriethoxysilane, and ethyltriethoxysilane.

  Furthermore, diphenyldimethoxysilane is preferred. When a unit (Ph-Si-Ph) in which two phenyl groups (Ph) are directly bonded to one Si is introduced into the metal oxide matrix, the flexibility of the metal oxide matrix is improved. This is preferable because the compatibility with the photopolymerizable compound and the organic polymer produced by polymerization thereof is improved. In addition, the refractive index of the metal oxide is increased. The Si diphenylalkoxide compound is readily available as a raw material, and has good hydrolysis and polymerization reactivity. Moreover, the phenyl group may have a substituent.

  When a monoalkoxysilane (j = 3, k = 1) such as trimethylmethoxysilane is present, the polymerization reaction is stopped, so that the monoalkoxysilane can be used to adjust the molecular weight.

Specific examples of the alkoxide compound (II) of the metal M _II other than Si are not particularly limited, but include pentaethoxytantalum (Ta (OEt) ₅ , tetra-t-butoxyzirconium (Zr (O-tBu) ₄ ), titanium Examples thereof include butoxide, etc. In addition to these, metal alkoxide compounds can be used.

  Alternatively, a multimer of metal alkoxide compound (II) (corresponding to a partial hydrolysis-condensation product of metal alkoxide compound (II)) may be used. A metal alkoxide compound (II) and a multimer of metal alkoxide compound (II) may be used in combination.

  The polyfunctional epoxy compound as the matrix forming material is a compound having at least two epoxy groups in the molecule. For example, as a polyfunctional epoxy compound, bisphenol A diglycidyl ether, bisphenol A diβ-methyl glycidyl ether, bisphenol F diglycidyl ether, bisphenol F diβ-methyl glycidyl ether, novolac type epoxy resins, trisphenol methane triglycidyl ether Glycidyl ethers such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether; Diglycidyl such as phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, dimer acid diglycidyl ester Glycol ester ethers; and the like. Although only 1 type of a polyfunctional epoxy compound may be used, 2 or more types may be used.

  The polyfunctional oxetanyl compound as a matrix forming material is a compound having at least two oxetanyl groups in the molecule. For example, as the polyfunctional oxetanyl compound, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, 3-ethyl-3- (phenoxymethyl) Examples thereof include polyfunctional oxetanyl compounds such as oxetane, di [1-ethyl- (3-oxetanyl)] methyl ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, and phenol novolac oxetane. Only one type of polyfunctional oxetanyl compound may be used, or two or more types may be used.

  The polyfunctional epoxy compound and / or polyfunctional oxetanyl compound is used to cross-link the cyclic ether groups of the metal alkoxide compound (I), but an organic moiety derived from the polyfunctional epoxy compound and / or polyfunctional oxetanyl compound. This improves the flexibility of the metal oxide matrix.

  In coupling the cyclic ether group, a thermal polymerization cationic curing agent such as an acid anhydride curing agent or an onium salt curing agent may be used.

In the present invention, the ratio of the cyclic ether group-containing metal alkoxide compound (I) or its multimer to the metal alkoxide compound (II) or its multimer as a matrix-forming material is the metal M _I , M _II. In addition, since it depends on the cyclic ether group-containing organic group R _E that contributes to flexibility and the alkyl group or aryl group R ₂₂ , the entire metal alkoxide compound [ Included in cyclic ether group-containing metal alkoxide compound (I) and its multimer per mole of metal atom contained in (multimer of (I) + (I) + multimer of (II) + (II)] The total number of metal atoms may be 0.05 to 0.9 mol, preferably 0.1 to 0.8 mol, for example, when m = 1 in the general formula (I). ) For example 0.025 to 0.45 mole in case of m = 2, preferably may be such that a 0.05 to 0.4 molar.

In order to obtain a desired refractive index of the metal oxide matrix, the metal alkoxide compound (I) or a multimer thereof and the metal alkoxide compound (II) or a multimer thereof are considered in a comprehensive manner. metal M _I contained in I) (II), as M _II is 2 or more, may be determined the proportion of these metals appropriately. For example, the number of silicon (s) and the number of metals other than Si (Ti, Ta, Zr, Ge, Sn, Al, Zn) (p) are:
0.3s ≦ p ≦ 3s
It is preferable that the relationship is satisfied.

  In the present invention, the amount in the case of using either or both of the polyfunctional epoxy compound and the polyfunctional oxetanyl compound is the total number of the cyclic ether group-containing metal alkoxide compound (I) and the cyclic ether group of the multimer. On the other hand, the total of the number of epoxy groups of the polyfunctional epoxy compound and the number of oxetanyl groups of the polyfunctional oxetanyl compound may be 0.1 to 10, preferably 0.1 to 5.0.

  Further, the metal oxide matrix may contain other trace elements other than those described above.

  In the present invention, the photopolymerizable compound is a photopolymerizable monomer. As the photopolymerizable compound, a radical polymerizable compound is preferable.

  The radically polymerizable compound is not particularly limited as long as it has one or more radically polymerizable unsaturated double bonds in the molecule. For example, a monofunctional or polyfunctional compound having a (meth) acryloyl group or a vinyl group can be used. Functional compounds can be used. The (meth) acryloyl group is a generic term for a methacryloyl group and an acryloyl group.

Among such radically polymerizable compounds, compounds having a (meth) acryloyl group include phenoxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and benzyl (meth). Acrylate, cyclohexyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methyl (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, stearyl (meth) acrylate, etc. Monofunctional (meth) acrylate;
Trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate Polyfunctional (meth) acrylates such as polyethylene glycol di (meth) acrylate, bis (2-hydroxyethyl) isocyanurate di (meth) acrylate, 2,2-bis [4- (acryloxy-diethoxy) phenyl] propane;
However, it is not necessarily limited to these.

  Examples of the compound having a vinyl group include monofunctional vinyl compounds such as styrene and ethylene glycol monovinyl ether; and polyfunctional vinyl compounds such as divinylbenzene, ethylene glycol divinyl ether, diethylene glycol divinyl ether, and triethylene glycol divinyl ether. However, it is not necessarily limited to these.

  Only 1 type of radically polymerizable compound may be used, and 2 or more types may be used together. In the present invention, when the metal oxide has a high refractive index and the organic polymer has a low refractive index, the low refractive index having no aromatic group among the above radical polymerizable compounds (for example, refractive index) (Rate 1.5 or less) is preferred. In order to further improve the compatibility with the metal oxide, more hydrophilic glycol derivatives such as polyethylene glycol (meth) acrylate and polyethylene glycol di (meth) acrylate are preferred.

  In the present invention, the photopolymerizable compound is used, for example, about 5 to 1000% by weight, preferably 10 to 300% by weight, based on the weight of the entire metal oxide matrix. If it is less than 5% by weight, it is difficult to obtain a large refractive index change during recording, and if it exceeds 1000% by weight, it is difficult to obtain a large refractive index change during recording.

  In the present invention, the hologram recording material composition further contains a photopolymerization initiator corresponding to the wavelength of the recording light. By the photopolymerization initiator, polymerization of the photopolymerizable compound is promoted by exposure during recording, and higher sensitivity can be obtained.

  When a radical polymerizable compound is used as the photopolymerizable compound, a photo radical initiator is used. Examples of the photo radical initiator include Darocur 1173, Irgacure 784, Irgacure 651, Irgacure 184, and Irgacure 907 (all manufactured by Ciba Specialty Chemicals). The content of the photo radical initiator is, for example, about 0.1 to 10% by weight, preferably about 0.5 to 5% by weight, based on the radical polymerizable compound.

  In addition to the photopolymerization initiator, it is preferable to contain a dye that becomes a photosensitizer corresponding to the recording light wavelength. Examples of the photosensitizer include thioxanthones such as thioxanthen-9-one and 2,4-diethyl-9H-thioxanthen-9-one, xanthenes, cyanines, merocyanines, thiazines, acridines, Anthraquinones, squaryliums, etc. are mentioned. The amount of the photosensitizer used is preferably about 5 to 50% by weight of the photo radical initiator, for example, about 10% by weight.

Next, production of the hologram recording material will be described.
The hologram recording material of the present invention is not particularly limited,
Mixing the cyclic ether group-containing metal alkoxide compound (I) or a multimer thereof with the metal alkoxide compound (II) not containing a cyclic ether group or a multimer thereof;
Hydrolyzing the mixed alkoxide compound and simultaneously or subsequently subjecting a cyclic ether group to a cation coupling reaction to obtain a precursor of a metal oxide matrix;
Before the hydrolysis, when hydrolyzing, or after hydrolysis, mixing the photopolymerizable compound;
A step of proceeding a polycondensation reaction of a metal oxide precursor mixed with a photopolymerizable compound;
It is preferable to manufacture by the manufacturing method of a hologram recording material provided with these.

  First, the cyclic ether group-containing metal alkoxide compound (I) or a multimer thereof in a predetermined ratio is mixed with the metal alkoxide compound (II) or a multimer thereof. The mixed alkoxide compound is hydrolyzed and polymerized, and simultaneously or subsequently, the cyclic ether group is subjected to a cation coupling reaction to obtain a metal oxide matrix precursor.

  This hydrolysis and polymerization reaction can be carried out under the same operation and conditions as in the known sol-gel method. For example, a predetermined proportion of a metal alkoxide compound raw material (a cyclic ether group-containing alkyltrialkoxide compound of Si, a diphenyl dialkoxide compound of Si, and a tetraalkoxide compound of Ti) is dissolved in an appropriate good solvent as a uniform solution, and the solution The reaction can be carried out by adding a suitable acid catalyst dropwise to the solution and stirring the solution in the presence of water. Although the quantity of a solvent is not limited, It is good to set it as 10-1000 weight part with respect to 100 weight part of the whole metal alkoxide compound.

  Examples of such a solvent include water; alcohols such as methanol, ethanol, propanol, isopropanol, and butanol; ethers such as diethyl ether, dioxane, dimethoxyethane, and tetrahydrofuran; N-methylpyrrolidone, acetonitrile, dimethylformamide, dimethyl Examples include acetamide, dimethyl sulfoxide, acetone, benzene and the like. What is necessary is just to select suitably from these. Or it can also be set as these mixed solvents.

  However, when a Ti alkoxide compound is used, dioxane, tetrahydrofuran, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, acetylacetone and the like should not be used. According to the study by the present inventors, ether oxygen of a cyclic ether skeleton and carbonyl oxygen have high coordination ability to Ti, and Ti formed between these organic solvents and Ti during the sol-gel reaction. It has been found that the resulting metal oxide matrix can absorb blue light by the complex (or coordination to Ti). Suitable organic solvents when using Ti alkoxide compounds include monoalcohols, dialcohols, and monoalkyl ethers of dialcohols. Specifically, monoalcohols such as methanol, ethanol, propanol, isopropanol and butanol; dialcohols such as ethylene glycol and propylene glycol; dialcohols such as 1-methoxy-2-propanol and ethylene glycol monomethyl ether (methyl cellosolve) Examples thereof include monoalkyl ethers of alcohol. What is necessary is just to select suitably from these. Or it can also be set as these mixed solvents. Further, water may be additionally used. These solvents have low coordination ability to Ti or do not produce a low energy transition absorption band even when coordinated. Therefore, even if these solvents remain in the metal oxide matrix, the absorption of the matrix to blue light is reduced.

  Examples of the acid catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid; formic acid, acetic acid, trichloroacetic acid, trifluoroacetic acid, propionic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, and the like. Organic acids and the like.

  Although it depends on the reactivity of the metal alkoxide compound, the hydrolysis polymerization reaction can generally be performed at room temperature, and can be performed at a temperature of about 0 to 150 ° C., preferably at a temperature of about room temperature to 50 ° C. The reaction time may be appropriately determined in relation to the reaction temperature, but is about 0.1 to 240 hours. The reaction may be performed under an inert atmosphere such as nitrogen gas, or may be performed under reduced pressure of about 0.5 to 1 atm while removing alcohol generated by the polymerization reaction.

  Simultaneously with the hydrolysis and polymerization, or subsequent to the hydrolysis and polymerization, the cyclic ether group is subjected to a cation coupling reaction to obtain a precursor of the metal oxide matrix. In the cation coupling reaction, a suitable curing agent such as an acid anhydride curing agent or an onium salt curing agent may be added. Examples of the curing agent include methyltetrahydrophthalic anhydride, aromatic sulfonium salt, aromatic iodonium salt, benzylpyridinium salt, benzylammonium salt, and heterocyclic ammonium salt. When using the crosslinkable component of a polyfunctional epoxy compound and / or a polyfunctional oxetanyl compound, these crosslinkable components are added before the cation coupling reaction of the cyclic ether group. During the cationic coupling reaction of the cyclic ether group, the crosslinking reaction by the crosslinkable component also proceeds, and a metal oxide matrix precursor is obtained.

  The cation coupling reaction can be performed under the same conditions as the hydrolysis polymerization reaction described above, and can be generally performed at room temperature, and is performed at a temperature of about 0 to 150 ° C., preferably at a temperature of about room temperature to 50 ° C. it can. The reaction time may be appropriately determined in relation to the reaction temperature, but is about 0.1 to 240 hours. The reaction may be performed in an inert atmosphere such as nitrogen gas.

  The photopolymerizable organic compound is mixed before hydrolysis, during hydrolysis, or after hydrolysis. The photopolymerizable organic compound and the metal alkoxide compound raw material may be mixed after hydrolysis, or may be mixed during hydrolysis or before hydrolysis. When mixing after hydrolysis, it is preferable to add and mix the photopolymerizable organic compound while the sol-gel reaction system containing the metal oxide or its precursor is in a sol state in order to mix uniformly. Moreover, mixing of a photoinitiator and a photosensitizer can also be performed before the said hydrolysis, when hydrolyzing, or after a hydrolysis.

  A hologram recording material in which a photopolymerizable compound and a sol-state metal oxide or precursor thereof are uniformly mixed is obtained. A hologram recording material layer is obtained by applying a hologram recording material on a substrate and advancing solvent drying and sol-gel reaction. In this way, a hologram recording material layer in which the photopolymerizable compound is uniformly contained in the metal oxide matrix is produced.

  The hologram recording medium of the present invention comprises at least the hologram recording material layer. Usually, the hologram recording medium includes a support base (that is, a substrate) and a hologram recording material layer. However, the hologram recording medium may include only a hologram recording material layer without the support base. For example, by forming a hologram recording material layer on a substrate by coating and then peeling the hologram recording material layer from the substrate, a medium composed only of the hologram recording material layer can be obtained. In this case, the hologram recording material layer is a thick film of the order of mm, for example.

  The hologram recording medium is a medium configured to reproduce with transmitted light (hereinafter referred to as a transmitted light reproduction type) or a medium configured to reproduce with reflected light (hereinafter referred to as a reflected light reproduction type) depending on the optical system apparatus used. Either.

  The hologram recording medium of the present invention is suitable not only for green laser light but also for recording / reproducing with blue laser light having a wavelength of 350 to 450 nm. When reproducing with transmitted light, it is preferable to have a light transmittance of 50% or more at a wavelength of 405 nm, and when reproducing with reflected light, it is preferable to have a light reflectance of 25% or more at a wavelength of 405 nm.

  By using the hologram recording material, a hologram recording medium having a recording layer thickness of 100 μm or more suitable for data storage can be obtained. The hologram recording medium can be produced by forming a film-like hologram recording material on a substrate or sandwiching a film-like hologram recording material between substrates.

  In the transmitted light reproduction type medium, it is preferable to use a material transparent to the recording / reproducing wavelength such as glass or resin for the substrate. The surface of the substrate opposite to the hologram recording material layer is preferably provided with an antireflection film for the recording / reproducing wavelength and an address signal or the like to prevent noise. It is preferable that the refractive index of the hologram recording material and the refractive index of the substrate are substantially equal in order to prevent interface reflection that becomes noise. Further, a refractive index adjustment layer made of a resin material or an oil material having a refractive index substantially equal to that of the recording material or the substrate may be provided between the hologram recording material layer and the substrate. In order to maintain the thickness of the hologram recording material layer between the substrates, a spacer suitable for the thickness between the substrates may be provided. Further, the end surface of the recording material medium is preferably sealed with the recording material.

  In the reflected light reproduction type medium, it is preferable that a material transparent to the recording / reproducing wavelength such as glass or resin is used for the substrate positioned on the incident side of the reproducing laser beam. A substrate with a reflective film is used as the substrate positioned on the incident side of the reproduction laser beam. Specifically, a reflective film made of, for example, Al, Ag, Au, or an alloy containing these metals as a main component is deposited on the surface of a rigid substrate made of glass or resin (translucency is not necessary). Films are formed by various film forming methods such as sputtering and ion plating to obtain a substrate with a reflective film. A hologram recording material layer is provided with a predetermined thickness on the surface of the reflective film of the substrate, and a light transmitting substrate is bonded to the surface of the recording material layer. An adhesive layer, a planarizing layer, or the like may be provided between the hologram recording material layer and the reflective film and / or between the hologram recording material layer and the translucent substrate. It must not interfere with light transmission. Other than that, it is the same as in the above-mentioned transmitted light reproduction type medium.

  The hologram recording medium having the hologram recording material of the present invention can be suitably used not only for a system for recording / reproducing with a green laser beam but also for a system for recording / reproducing with a blue laser beam with a wavelength of 350 to 450 nm. .

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

[Example 1]
Using 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, diphenyldimethoxysilane, and titanium butoxide multimer represented by the following structural formula, a hologram recording material is prepared by the following procedure by the sol-gel method. did.

(Synthesis of matrix material)
2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane (3.0 g), diphenyldimethoxysilane (3.0 g), and titanium butoxide multimer (Nihon Soda Co., Ltd., B-10) (7.2 g) were combined with 1-methoxy-2. -It mixed in 40 mL of propanol solvents, and was set as the metal alkoxide solution. That is, the molar ratio of Si / Ti was 1.0 / 1.3.

  A solution consisting of 2.1 mL of water, 0.3 mL of 1N hydrochloric acid aqueous solution and 5 mL of 1-methoxy-2-propanol was dropped into the metal alkoxide solution at room temperature while stirring, and the hydrolysis reaction was carried out by continuing stirring for 2 hours. . Next, 0.9 g of bisphenol A type epoxy monomer (Dainippon Ink & Chemicals, Epicron 850-S) and 0.1 g of methyltetrahydrophthalic anhydride (Dainippon Ink & Chemicals, Epicron B-570) as a curing agent Was added to the reaction system and further stirred for 2 hours. In this way, a sol solution was obtained.

(Photopolymerizable compound)
100 parts by weight of polyethylene glycol diacrylate (manufactured by Toagosei Co., Ltd., M-245) as a photopolymerizable compound, 3 parts by weight of IRG-907 (Ciba Specialty Chemicals) as a photopolymerization initiator, and thioxanthene as a photosensitizer -9-one 0.3 weight part was added and it was set as the mixture containing a photopolymerizable compound.

(Hologram recording material)
The sol solution and the mixture of the photopolymerizable compound are mixed at room temperature so that the ratio of the matrix material (as a non-volatile component) is 67 parts by weight and the ratio of the photopolymerizable compound is 33 parts by weight. A hologram recording material solution was obtained.

  The obtained hologram recording material solution was applied onto a glass substrate as described below and dried to obtain a recording medium sample.

A description will be given with reference to FIG. 1 showing a schematic cross section of a hologram recording medium.
A 1 mm thick glass substrate (22) provided with an antireflection film (22a) on one side was prepared. A spacer (24) having a predetermined thickness is placed on the surface of the glass substrate (22) where the antireflection film (22a) is not provided, the resulting hologram recording material solution is applied, dried at room temperature for 1 hour, and then It dried at 40 degreeC for 24 hours and volatilized the solvent. By this drying step, gelation (condensation reaction) of the organometallic compound was advanced to obtain a hologram recording material layer (21) having a dry film thickness of 400 μm in which the organometallic compound and the photopolymerizable compound were uniformly dispersed.

(Hologram recording medium)
The hologram recording material layer (21) formed on the glass substrate (22) was covered with another 1 mm thick glass substrate (23) provided with an antireflection film (23a) on one side. At this time, the surface of the glass substrate (23) where the antireflection film (23a) was not provided was covered so as to be in contact with the surface of the hologram recording material layer (21). Thus, a hologram recording medium (11) having a structure in which the hologram recording material layer (21) was sandwiched between two glass substrates (22) and (23) was obtained.

(Characteristic evaluation)
The obtained hologram recording medium sample was evaluated for characteristics in a hologram recording optical system as shown in FIG. The direction of the paper surface of FIG.

  In FIG. 2, the hologram recording medium sample (11) is set so that the recording material layer is perpendicular to the horizontal direction.

  In the hologram recording optical system of FIG. 2, a light source (101) of a single mode oscillation semiconductor laser (405 nm) is used, and light oscillated from the light source (101) is converted into a beam rectifier (102), an optical isolator (103), a shutter. (104) Spatial filtering and collimation were performed by a convex lens (105), a pinhole (106), and a convex lens (107), and the beam diameter was expanded to about 10 mmφ. From the expanded beam, 45-degree polarized light was extracted through a mirror (108) and a half-wave plate (109), and was divided into S wave / P wave = 1/1 by a polarizing beam splitter (110). The divided S wave is converted into an S wave through a mirror (115), a polarizing filter (116), an iris diaphragm (117), and the divided P wave is converted into an S wave using a half-wave plate (111). (112) Via the polarizing filter (113) and the iris diaphragm (114), the total incident angle θ of the two light beams on the hologram recording medium sample (11) is 37 °. Interference fringes were recorded.

  The hologram is multiplexed by rotating the sample (11) in the horizontal direction (angle multiplexing: sample angle -21 ° to + 21 °, angular interval 3 °), and centered on the vertical axis with respect to the sample (11) plane And rotated and recorded (Peristrophic multiplexing, sample angle 0 ° to 90 °, angular interval 10 °). Multiplicity is 150. At the time of recording, the iris diaphragm (114) and the same (117) were exposed to 4φ.

Details of the multiple recording will be described. Sample (11) is multiplexed by rotating in the horizontal direction (centered on the vertical axis with respect to the paper surface) from -21 ° to + 21 ° at an angular interval of 3 °, and then sample (11) is perpendicular to the sample (11) surface. Rotate 10 degrees around the axis (10 degrees when viewed from the laser beam incident side), rotate again in the horizontal direction from -21 degrees to +21 degrees at an angular interval of 3 degrees, and repeat this 10 times. (11) was rotated from 0 ° to 90 ° about the vertical axis with respect to the sample (11) plane, and multiplex recording with a multiplicity of 150 was performed.
The position at which the sample (11) plane is 90 ° with respect to a center line (not shown) that bisects the angle θ formed by the two light beams is defined as ± 0 ° in horizontal rotation. The vertical axis with respect to the sample (11) plane is the vertical axis passing through the intersection of two diagonal lines when the sample (11) is rectangular, and the center of the circle when the sample (11) is circular. The vertical axis through.

  After hologram recording, sufficient light was irradiated with only one light beam in order to react the remaining unreacted components. During reproduction, the shutter (121) is shielded from light, the iris diaphragm (117) is 3φ and only one light beam is irradiated, and the sample (11) is continuously rotated in the horizontal direction from −23 ° to + 23 °. Further, the sample was rotated at an angular interval of 10 ° from 0 ° to 90 ° around the vertical axis with respect to the sample (11) plane, and the diffraction efficiency was measured with a power meter (120) at each angular position. When there is no volume change (recording shrinkage) or average refractive index change of the recording material layer before and after recording, the horizontal diffraction peak angle coincides between recording and reproduction. However, in practice, since recording shrinkage and change in average refractive index occur, the horizontal diffraction peak angle during reproduction slightly deviates from the horizontal diffraction peak angle during recording. For this reason, during reproduction, the angle in the horizontal direction was continuously changed, and the diffraction efficiency was determined from the peak intensity when a diffraction peak appeared. In FIG. 2, reference numeral (119) denotes a power meter that is not used in this embodiment.

  At this time, the dynamic range: M # (sum of square roots of diffraction efficiency) was as high as 17.8 (value converted when the thickness of the hologram recording material layer was 1 mm). The light transmittance of the medium (recording layer thickness: 400 μm) at 405 nm before recording exposure (initial stage) was 76%. No decrease in the light transmittance of the medium at 405 nm (recording wavelength) after recording was observed.

  At this time, the decrease in light transmittance by the glass substrates with antireflection films (22) and (23) was 0.6%. That is, referring to FIG. 1, when laser light is incident on the sample (11) from the substrate (22) side and transmitted toward the substrate (23), the presence of the antireflection film (22a) causes air and 0.3% is reflected at the interface with the antireflection film (22a), 99.7% is transmitted (absorption is 0%), and the interface between the antireflection film (23a) of the substrate (23) and air As a result, 99.4% of the transmitted light (i.e., 99.7%) is reflected.

  Since the refractive index of the glass substrates (22) and (23) and the refractive index of the hologram recording material layer (21) are substantially equal, the interface between the glass substrate (22) and the recording material layer (21), and the recording material layer ( The reflection is negligible at the interface between 21) and the glass substrate (23).

Next, an environmental resistance test of the hologram recording medium was performed as follows.
The produced hologram recording medium sample (11) was stored in an environment of 80 ° C. for 50 hours. After storage, the characteristics were evaluated using the hologram recording optical system shown in FIG. 2 in the same manner as described above. At this time, the dynamic range: M # was maintained at a high value of 16.1 (a value converted when the thickness of the hologram recording material layer was 1 mm). The light transmittance of the medium at 405 nm before recording exposure (after storage at high temperature) was 75%. No decrease in the light transmittance of the medium at 405 nm after recording was observed.

[Comparative Example 1]
(Synthesis of matrix material)
7.8 g of diphenyldimethoxysilane and 7.2 g of titanium butoxide multimer (manufactured by Nippon Soda Co., Ltd., B-10) were mixed in 40 mL of a tetrahydrofuran solvent to obtain a metal alkoxide solution. That is, the Si / Ti molar ratio was 1/1.

  A solution consisting of 2.1 mL of water, 0.3 mL of 1N hydrochloric acid aqueous solution and 5 mL of tetrahydrofuran was dropped into the metal alkoxide solution at room temperature while stirring, and stirring was continued for 2 hours to conduct a hydrolysis reaction. In this way, a sol solution was obtained.

  Thereafter, in the same manner as in Example 1, a hologram recording material solution was prepared to produce a hologram recording medium.

  The obtained hologram recording medium sample was evaluated for characteristics in the same manner as in Example 1. At this time, the dynamic range: M # was 8.7 (value converted when the thickness of the hologram recording material layer was 1 mm), which was lower than that of Example 1. In addition, the light transmittance of the medium (recording layer thickness: 400 μm) at 405 nm before recording exposure (initial) was 43%, which was lower than the light transmittance in Example 1, and the light transmittance further decreased after recording. .

  Next, the obtained hologram recording medium sample was evaluated for characteristics after high-temperature storage in the same manner as in Example 1. At this time, the dynamic range: M # was lowered to 4.2 (value converted when the thickness of the hologram recording material layer was 1 mm). The light transmittance of the medium at 405 nm before recording exposure (after storage at high temperature) was 41%, and the light transmittance further decreased after recording.

  In Example 1, a hologram recording medium sample was prepared using an epoxy group-containing metal alkoxide compound as a matrix forming material. As a result, the obtained hologram recording medium sample showed a high dynamic range (17.8, 16.1) both in the initial stage and after storage at high temperature.

  On the other hand, in Comparative Example 1, a hologram recording medium was produced without using an epoxy group-containing metal alkoxide compound as a matrix forming material. The obtained hologram recording medium had an initial dynamic range of 8.7 and a very low value compared to Example 1. Furthermore, the dynamic range after storage at high temperature was remarkably lowered to 4.2. In the medium of Comparative Example 1, alkoxy groups and hydroxyl groups remaining unreacted in the matrix were gradually condensed during high-temperature storage, so that the mobility of the monomer during recording is considered to have decreased.

  In the medium of Example 1, since a matrix was formed by carrying out a cation coupling reaction of epoxy groups, a high crosslink density was already achieved at the time of preparation of the medium (initial stage). As a result, even if unreacted alkoxy groups and hydroxyl groups remain in the matrix, the movement of these reactive groups is restricted to some extent, and there are hardly any reactive groups capable of condensing in the vicinity. The condensation reaction therein was suppressed, and the high-temperature storage stability was improved. Moreover, since the cation initiator used at the time of the cation coupling reaction also promotes the sol-gel reaction, the absolute number of alkoxy groups and hydroxyl groups remaining unreacted was small. For this reason, it is considered that the medium of Example 1 achieved a high dynamic range both in the initial stage and after storage at a high temperature.

It is a figure which shows the schematic cross section of the hologram recording medium produced in the Example. It is a top view which shows the outline of the hologram recording optical system used in the Example.

Explanation of symbols

(11): Hologram recording medium
(21): Hologram recording material layer
(22a) (23a): Antireflection film
(22) (23): Glass substrate
(24): Spacer

Claims (7)

A hologram recording material comprising a metal oxide matrix and a photopolymerizable compound,
Metal oxide matrix
Formula (I):
(R _E ) m M _I (OR ₁₁ ) n (I)
(Here, R _E represents a cyclic ether group-containing organic group, R ₁₁ represents an alkyl group, M _I represents a metal, m represents 1, 2 or 3, n represents an integer of 1 or more, However, m + n is the valence number of metal M _I.)
A cyclic ether group-containing metal alkoxide compound (I) represented by
General formula (II):
(R ₂₂ ) j M _II (OR ₂₁ ) k (II)
(Here, R ₂₂ represents an alkyl group or an aryl group, R ₂₁ represents an alkyl group, M _II represents a metal, j represents 0, 1, 2, or 3, and k represents an integer of 1 or more.) , however, j + k is the valence number of metal M _II.)
A hologram recording material formed from a matrix-forming material containing at least the metal alkoxide compound (II) represented by the formula (II) or a multimer thereof.   The hologram recording material according to claim 1, wherein the cyclic ether group of the metal alkoxide compound (I) is an epoxy group or an oxetanyl group.   The hologram recording material according to claim 1, wherein the matrix forming material further contains at least one selected from the group consisting of a polyfunctional epoxy compound and a polyfunctional oxetanyl compound. Metal M _I is at cyclic ether group-containing metal alkoxide compound (I), is Si, the hologram recording material according to claim 1 to any one of claims 1 to 3. Metal alkoxide compound (II) is different from at least two are used with metal M _II, 1 kind of metal M _II is a Si, other metals M _II other than Si is, Ti, Ta, Zr, Ge , The hologram recording material according to claim 1, wherein the hologram recording material is selected from the group consisting of Sn, Al, and Zn.   Furthermore, the hologram recording material of any one of Claims 1-5 containing a photoinitiator. A hologram recording medium having a hologram recording layer made of the hologram recording material according to claim 1.

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