JP2008292712A - Hologram recording material and hologram recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram recording material and a hologram recording medium suitable for volume hologram recording, achieving high refractive index change, flexibility, high sensitivity, low scattering, environmental resistance, durability, low dimensional change (low shrinkage) and high multiplicity even in holographic memory recording by using not only a green laser but also a blue laser. <P>SOLUTION: The hologram recording material contains a metal oxide matrix and a photopolymerizable compound, wherein the metal oxide matrix contains at least Ti and Si as metal elements, glycol is coordinated with Ti, and a hydrophilic organic group is directly coupled to a part of Si through a Si-C coupling. The hologram recording medium 11 has a layer 21 of the hologram recording material. <P>COPYRIGHT: (C)2009,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. 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 a hologram recording 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, in Japanese Patent Application Laid-Open No. 2005-321684, at least two kinds of metals (Si, Ti), oxygen, and aromatic groups are included, and two aromatic groups are directly bonded to one metal (Si). A hologram recording material containing an organometallic compound having an organometallic unit (organic-inorganic hybrid matrix) and a photopolymerizable compound (organic monomer) 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.

JP-A-2005-321684

  The above publication discloses holographic memory recording using a green laser, but does not disclose holographic memory recording using a blue laser.

  As a result of studies by the present inventors, when holographic memory recording is performed on a hologram recording medium disclosed in Japanese Patent Application Laid-Open No. 2005-321684 using a blue laser, a decrease in transmittance occurs, resulting in good holographic memory recording characteristics. I knew that I couldn't get it. And it turned out that the fall of the transmittance | permeability originates in coloring at the time of forming the metal oxide matrix which contains Ti as a structural metal element by the sol-gel method. When the transmittance is lowered, holograms (interference fringes) are formed unevenly in the recording layer in the thickness direction, resulting in scattering noise and the like. It has been found that in order to obtain good holographic image characteristics, the medium needs to have a light transmittance of 50% or more.

  The light transmittance of the hologram recording layer depends on its thickness. If the thickness of the recording layer is reduced, the light transmittance is improved, but the width of the diffraction peak obtained when the reproduction light is incident on the recorded pattern is widened, and the separation between adjacent diffraction peaks is poor. Become. Therefore, in order to obtain a sufficient S / N ratio, it is necessary to widen a shift interval (an angle or the like) during multiplex recording, and therefore, a high multiplicity cannot be achieved. In order to achieve holographic memory recording characteristics that ensure high multiplicity, a recording layer having a thickness of at least 100 μm is required no matter what recording system the hologram recording medium is used in.

  The object of the present invention is to use a metal oxide containing titanium and silicon with reduced coloring as a metal oxide matrix, and to achieve a high refractive index change not only in a green laser but also in a holographic memory recording using a blue laser. To provide a hologram recording material suitable for volume hologram recording, which achieves flexibility, high sensitivity, low scattering, environmental resistance, durability, low dimensional change (low shrinkage), and high multiplicity. is there. Another object of the present invention is to provide a hologram recording medium having a hologram recording layer made of the hologram recording material.

  When the present inventors form a metal oxide matrix containing Ti and Si as constituent metal elements by a sol-gel method, the alkoxide compound of Ti coordinated with glycol is subjected to hydrolysis and polycondensation reaction. It has been found that coloring of the resulting metal oxide is greatly reduced. Furthermore, moderate compatibility between the metal oxide matrix and the photopolymerizable monomer can be achieved by having a hydrophilic organic group directly bonded to the Si via a Si-C bond in a part of the Si. It has been found that the high mobility of the photopolymerizable monomer in the matrix at the time of recording is compatible.

The present invention includes the following inventions.
(1) A hologram recording material comprising a metal oxide matrix and a photopolymerizable compound,
The metal oxide matrix contains at least Ti and Si as metal elements, and glycol is coordinated to Ti, and a hydrophilic organic group is partly included in Si through Si—C bonds. Hologram recording material that is directly bonded to.

  (2) The hologram recording material according to (1), wherein the glycol is a glycol other than a seminar diol.

（式中、Ｒ₁ 、Ｒ₂ 、Ｒ₃ 、Ｒ₄ 、Ｒ₅ 及びＲ₆ は、同一でも異なっていてもよく、水素原子又はアルキル基を表し、ただし、Ｒ₁ 、Ｒ₂ 、Ｒ₃ 、Ｒ₄ 、Ｒ₅ 及びＲ₆ に含まれる炭素数の総和は０〜５である。）
で表される、上記(1) 又は(2) に記載のホログラム記録材料。 (3) The glycol has the general formula (I):

(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ may be the same or different and each represents a hydrogen atom or an alkyl group, provided that R ₁ , R ₂ , R ₃ , The total number of carbon atoms contained in R ₄ , R ₅ and R ₆ is 0-5.)
The hologram recording material according to (1) or (2), which is represented by:

(4) The hydrophilic organic group has a solubility parameter value (SP value) determined by the Fedors estimation method of 21.5 (J / cm ³ ) ^0.5 or more, (1) to (3) The hologram recording material according to any one of the above.

  (5) At least a part of Si other than Si to which the hydrophilic organic group is bonded, an aromatic hydrocarbon group is directly bonded to the Si via a Si-C bond, 1) The hologram recording material according to any one of (4).

(6) The photopolymerizable compound is a polyethylene glycol unit represented by the following formula:
− (CH ₂ CH ₂ O) p −
(Where p represents the number of repeating units of ethylene oxide)
The hologram recording material according to any one of (1) to (5) above, which is a radically polymerizable compound having

  (7) The hologram recording material according to (6), wherein the number of repeating units p is 3 or more.

  (8) The hologram recording material according to any one of (1) to (7), further comprising a photopolymerization initiator.

  (9) A hologram recording medium having a hologram recording layer made of the hologram recording material according to any one of (1) to (8).

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

  (11) The hologram recording medium according to (9) or (10), wherein the hologram recording layer has a thickness of at least 100 μm.

(12) At least Ti and Si are contained as metal elements, and glycol is coordinated to Ti, and hydrophilic organic groups are directly bonded to Si through Si-C bonds in a part of Si. A method for producing a hologram recording material comprising a metal oxide matrix and a photopolymerizable compound,
Preparing a alkoxide compound of Ti coordinated with glycol;
An alkoxide compound of Ti coordinated with the glycol (a);
An Si alkoxide compound (b-1) in which a hydrophilic organic group is directly bonded to Si via a Si-C bond;
Mixing the Si alkoxide compound (b-2) other than (b-1);
Hydrolyzing the mixed alkoxide compound to obtain a metal oxide precursor;
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:

  (13) The method for producing a hologram recording material according to (12), wherein the glycol is a glycol other than a seminal diol.

(14) In the step of preparing the Ti alkoxide compound,
The method for producing a hologram recording material according to the above (12) or (13), wherein a step of mixing a alkoxide compound of Ti and glycol and coordinating the glycol to the Ti alkoxide compound is performed.

  In the hologram recording material of the present invention, glycol is coordinated to Ti of the metal oxide matrix, and hydrophilic organic groups are directly bonded to Si through Si—C bonds in a part of Si. is doing. This metal oxide matrix is obtained by subjecting a alkoxide compound of Ti coordinated with glycol and an alkoxide compound of Si to hydrolysis and polycondensation reaction, and coloring of the metal oxide is greatly reduced. Therefore, there is little absorption with respect to light having a wavelength in the blue region.

  Furthermore, moderate compatibility between the metal oxide matrix and the photopolymerizable monomer can be achieved by having a hydrophilic organic group directly bonded to the Si via a Si-C bond in a part of the Si. The high mobility of the photopolymerizable monomer in the matrix at the time of recording can be compatible. Since the compatibility is good, in any stage of the hologram recording layer formation stage (metal oxide matrix formation stage), the storage stage after the recording exposure after the hologram recording medium production, and the storage stage after the recording exposure However, the white turbidity phenomenon of the recording layer which has been conventionally observed does not occur.

  Therefore, the hologram recording medium using the hologram recording material of the present invention can obtain sufficient sensitivity and refractive index modulation in recording / reproduction using not only a green laser but also a blue laser, and before and after recording. It is excellent in storage stability (environmental resistance) at any stage.

  The hologram recording material of the present invention contains at least Ti and Si as metal elements, glycol is coordinated to Ti, and a hydrophilic organic group is bonded to a part of Si through a Si-C bond. It consists of a composition containing a metal oxide (organic-inorganic hybrid) matrix directly bonded to Si and a photopolymerizable compound (monomer). By including two kinds of metals, Ti and Si, as constituent elements, it is easy to control characteristics such as the refractive index, which is preferable in designing the recording material. The hologram recording medium of the present invention has a hologram recording layer made of the hologram recording material. In this specification, the hologram recording layer is sometimes referred to as a hologram recording material layer.

  The metal oxide matrix may be formed by a sol-gel reaction (that is, hydrolysis / polycondensation) from a matrix-forming material containing a metal alkoxide compound and / or a multimer (partial hydrolysis condensate) described later. It is 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 is preferably used in a relatively large content.

The metal oxide matrix includes the following (a), (b-1), and (b-2):
(A) a Ti alkoxide compound coordinated with glycol and / or a multimer thereof,
(B-1) Si alkoxide compound in which a hydrophilic organic group is directly bonded to Si via a Si-C bond and / or its multimer, and (b-2) Si alkoxide other than (b-1) above It can be formed by a sol-gel reaction from a matrix-forming material containing a compound and / or a multimer thereof. A multimer corresponds to a partially hydrolyzed condensate of a metal alkoxide compound. The Ti alkoxide compound (a) and the Si alkoxide compounds (b-1) and (b-2) may be not only mononuclear but also multinuclear.

  In addition to the metal alkoxide compound, the metal oxide matrix includes at least one metal selected from the group consisting of other metal alkoxide compounds, such as Zr alkoxide compounds, Ta alkoxide compounds, and Sn alkoxide compounds. An alkoxide compound; and / or a matrix forming material containing a multimer (partially hydrolyzed condensate) of the metal alkoxide compound can be formed by a sol-gel reaction.

  First, a Ti alkoxide compound (a) coordinated with glycol is prepared. The glycol is preferably a glycol other than the seminar diol in consideration of the coordination ability to the Ti atom. This preparatory step is preferably performed by mixing Ti alkoxide compound and glycol, and coordinating glycol to Ti alkoxide compound. Alternatively, a alkoxide compound of Ti coordinated with glycol may be obtained and used as a starting material.

  When the Ti alkoxide compound in a state where the glycol is coordinated is subjected to hydrolysis (and polycondensation), another coordination compound (for example, tetrahydrofuran) is formed during the sol-gel reaction due to coordination of the glycol to the Ti atom. Coordination properties such as (THF) do not occur with Ti atoms.

  According to the study by the present inventors, the coloration of the titanium-containing metal oxide that occurs during the sol-gel reaction is caused by the coordination of the coordination compound to the Ti atom, particularly coordination via π electrons. Conceivable. Therefore, by subjecting the alkoxide compound of Ti coordinated with glycol to hydrolysis, the coordination of another coordinated compound to the Ti atom is suppressed, and the glycol is coordinated to the Ti atom via a hydrogen bond. Therefore, coloration due to the coordination of glycol does not occur, and coloration that occurs during the sol-gel reaction can be reduced.

  In the present invention, the glycol is preferably a glycol other than the seminal diol and vicinal diol in consideration of the coordination ability to the Ti atom, and further selected from those represented by the general formula (I). preferable.

In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ may be the same or different and each represents a hydrogen atom or an alkyl group, provided that R ₁ , R ₂ , R ₃ , R The total number of carbon atoms contained in ₄ , R ₅ and R ₆ is 0-5, preferably 2-5.

The alkyl group represented by R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ is a linear or branched lower alkyl group having up to 5 carbon atoms in order to satisfy the above total number of carbon atoms. . Examples include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group.

  Examples of the glycol represented by the general formula (I) include 1,3-propanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, and 2-ethyl-1,3-hexanediol. 2-methyl-2,4-pentanediol and the like.

  The above-mentioned glycol (that is, 1,3-diol) easily coordinates to the Ti atom of the Ti alkoxide compound raw material, satisfies the coordination position of the Ti atom, and another coordinating compound is Ti during the sol-gel reaction. Inhibits coordination with atoms. When the glycol is coordinated to the Ti alkoxide compound, the Ti alkoxide compound such as tetrabutoxy titanium and tetraethoxy titanium and the glycol are mixed in a solvent such as ethanol and butanol at room temperature, for example, and stirred. Good. In this case, the same solvent as that used in the sol-gel reaction may be used as the solvent. In this way, an alkoxide compound of Ti coordinated with glycol is prepared.

  Next, the Ti alkoxide compound (a) coordinated with the glycol and the Si alkoxide compounds (b-1) and (b-2) (and / or other metal alkoxide compounds as required) Mix to obtain a mixed alkoxide compound. Next, the mixed alkoxide compound is hydrolyzed (and polycondensed) to obtain a metal oxide precursor.

The Si alkoxide compound (b-1) in which the hydrophilic organic group is directly bonded to Si via the Si—C bond is represented, for example, by the following general formula (b-1).
Si (OR ₁₁ ) j (R _H ) k (R ₁₂ ) 4-jk (b-1)
Here, R ₁₁ represents an alkyl group, R _H represents a hydrophilic organic group, R ₁₂ represents an organic group, j represents 1, 2 or 3, k represents 1, 2 or 3, provided that , J + k is 2, 3 or 4. When j + k is 4, R ₁₂ is not present. That is, R ₁₂ is an arbitrary group. R ₁₁ may be different depending on j, R _H may be different _depending on k, and the same applies to R ₁₂ .

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. The —OR ₁₁ group is hydrolyzed in a sol-gel reaction.

The hydrophilic organic group represented by R _H is directly bonded to Si via a Si—C bond and is not hydrolyzed in the sol-gel reaction. The hydrophilic organic group represented by _RH is a method for estimating the solubility parameter (SP) proposed by Fedors in Polymer Engineering and Science, Vol. 14, No. 2, pp147-154 (1974) (so-called solubility parameter). The solubility parameter value (SP value) determined by the “Fedors method”) is defined as 21.5 (J / cm ³ ) ^0.5 or higher.

The estimation method has been proposed as a method for estimating the SP value of the whole molecule, in particular, a polymer, but can be sufficiently applied to the purpose of relatively quantitative comparison of the hydrophilicity of a part of a certain compound. In the present invention, the SP value (referred to as a local SP value for convenience) of the non-hydrolyzable group (that is, a group other than the —OR ₁₁ group) in the target Si alkoxide compound (b-1). calculate. A group having an SP value of 21.5 (J / cm ³ ) ^0.5 or more is regarded as a hydrophilic organic group R _H. On the other hand, a group having an SP value of less than 21.5 (J / cm ³ ) ^0.5 is defined as any group R ₁₂ other than the hydrophilic organic group R _H. There may be two or three hydrophilic organic groups R _{H in} one molecule of the Si alkoxide compound (b-1).

Further, when a plurality of Si atoms are contained in one molecule of the Si alkoxide compound (b-1), for example, in the case of the Si alkoxide compound of the following formula:
_{(R 11 O) 2 Si (} R 13) -R 14 -Si (R 15) (OR 11) 2
The atomic group R ₁₄ may be handled as one atomic group and obtain a local SP value. That is, in this case, the local SP value of each of R ₁₃ , R ₁₄ , and R ₁₅ is obtained, and the group having an SP value of 21.5 (J / cm ³ ) ^0.5 or more is a hydrophilic organic group R _H. Is done.

The organic group represented by R ₁₂ is an organic group other than R _H (SP value is less than 21.5 (J / cm ³ ) ^0.5 ), and is directly bonded to Si via a Si—C bond. It is not hydrolyzed in the gel reaction. R ₁₂ is, for example, an alkyl group or an aryl group, and the alkyl group represented by R ₁₂ is usually a lower alkyl group having about 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group. , Isobutyl group, sec-butyl group and the like. The aryl group represented by R ₁₂ include phenyl group. The alkyl group and aryl group may have a substituent.

By using the Si alkoxide compound (b-1) having the hydrophilic organic group R _H , the obtained metal oxide matrix has a hydrophilic organic group R _H having Si—C bonds in a part of Si. It is directly bonded to the Si. In such a metal oxide matrix, the hydrophobicity of the glycol coordinated to Ti is relaxed by the presence of the hydrophilic organic group R _H , and the photopolymerizable compound (monomer) generally containing a hydrophilic unit. Excellent compatibility. The preferred SP value of the hydrophilic organic group R _H is 23.0 (J / cm ³ ) ^0.5 or more, and the more preferred SP value is 25.0 (J / cm ³ ) ^0.5 or more, and the upper limit is not particularly defined. For example, 45.0 (J / cm ³ ) ^0.5 or less.

  Only 1 type may be used for Si alkoxide compound (b-1) which has a hydrophilic organic group, but 2 or more types may be used for it. Further, a multimer of Si alkoxide compound (b-1) [corresponding to a partial hydrolysis-condensation product of (b-1)] may be used. (B-1) and a multimer may be used in combination.

Specifically, the following compounds can be used as the Si alkoxide compound (b-1). Of course, it is not limited to these. The underline is the hydrophilic organic group _RH of interest and indicates its (local) SP value.

Hydroxymethyltriethoxysilane
_{HOCH 2 -Si (OC 2 H 5} ) 3 SP ^{value: 36.49 (J / cm 3)} 0.5

N- (3-Triethoxysilylpropyl) gluconamide
(C ₂ H ₅ O) ₃ Si— CH ₂ CH ₂ CH ₂ NHCO— [CH (OH)] ₅ —H SP value: 36.14 (J / cm ³ ) ^0.5

3-Bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane
NH ₂ —C (CH ₂ CHOH) ₂ CH ₂ CH ₂ —Si (OC ₂ H ₅ ) ₃ SP value: 34.88 (J / cm ³ ) ^0.5

3- [N- (2- hydroxyethyl) -N- methylamino] propyl trimethoxysilane _{HOCH 2 CH 2 -N (CH 3} ) -CH 2 CH 2 CH 2 -Si (OCH 3) 3 SP value: 23. 48 (J / cm ³ ) ^0.5

N- (3-triethoxysilylpropyl) -4-hydroxybutyramide
HOCH ₂ CH ₂ CH ₂ CONH-CH ₂ CH ₂ CH ₂ —Si (OC ₂ H ₅ ) ₃ SP value: 28.29 (J / cm ³ ) ^0.5

N, N′-bis (2-hydroxyethyl) -N, N ′-[bis (3-trimethoxysilyl) propyl] ethylenediamine
{HOCH ₂ CH ₂ —N [CH ₂ CH ₂ CH ₂ —Si (OC ₂ H ₅ ) ₃ ] CH ₂ —} ₂ SP value: 25.53 (J / cm ³ ) ^0.5

m-aminophenyltrimethoxysilane
m-NH ₂ Ph —Si (OCH ₃ ) ₃ SP value: 24.93 (J / cm ³ ) ^0.5

p-aminophenyltrimethoxysilane
p-NH ₂ Ph —Si (OCH ₃ ) ₃ SP value: 24.93 (J / cm ³ ) ^0.5

Chlorophenyl triethoxysilane
ClPh-Si (OC ₂ H ₅ ) ₃ SP value: 23.86 (J / cm ³ ) ^0.5

The Si alkoxide compound (b-2) other than (b-1) is represented by the following general formula (b-2), for example.
_{Si (OR 21) m (R} 22) n (R 23) 4-mn (b-2)
Here, R ₂₁ represents an alkyl group, R ₂₂ represents an aromatic group, R ₂₃ represents an organic group other than aromatic, m represents 1, 2 or 3, and n represents 1, 2 or 3. Where m + n is 2, 3 or 4. When m + n is 4, R ₂₃ is not present. That is, R ₂₃ is an arbitrary group. R ₂₁ may be different depending on m, R ₂₂ may be different depending on n, and the same applies to R ₂₃ .

The alkyl group represented by R ₂₁ has the same meaning as R ₁₁ in the Si alkoxide compound (b-1), and examples thereof include the same specific group. The —OR ₂₁ group is hydrolyzed in a sol-gel reaction.

The aromatic group R ₂₂ represents a phenyl group. The aromatic group may have a substituent. R ₂₂ has an SP value of less than 21.5 (J / cm ³ ) ^0.5 , is directly bonded to Si via a Si—C bond, and is not hydrolyzed in a sol-gel reaction.

The organic group other than aromatic represented by R ₂₃ is an organic group other than R ₂₂ (SP value is less than 21.5 (J / cm ³ ) ^0.5 ), and is directly bonded to Si via a Si—C bond. And is not hydrolyzed in the sol-gel reaction. R ₂₃ is, for example, an alkyl group, and the alkyl group represented by R ₂₃ is usually a lower alkyl group having about 1 to 4 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group. , Sec-butyl group and the like. The alkyl group may have a substituent.

  Specific examples of the Si alkoxide compound (b-2) include, for example, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane (above, m = 3, n = 1), diphenyldimethoxysilane, diphenyldiethoxysilane. (Above, m = 2, n = 2), t-butyldiphenylmethoxysilane, diphenylmethylethoxysilane (above, m = 1, n = 2) and the like.

  Of these, diphenyldimethoxysilane and diphenyldiethoxysilane are 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.

  Only 1 type may be used for Si alkoxide compound (b-2), but 2 or more types may be used. Further, a multimer of Si alkoxide compound (b-2) [corresponding to a partial hydrolysis-condensation product of (b-2)] may be used. (B-2) and a multimer may be used in combination.

  In addition to the Si alkoxide compounds (b-1) and (b-2), for example, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane and the like are used. Also good.

  When a monoalkoxysilane such as trimethylmethoxysilane is present, the polymerization reaction is stopped, so that the monoalkoxysilane can be used to adjust the molecular weight.

  In the present invention, the ratio of the Ti alkoxide compound (a) as the matrix-forming material, the hydrophilic organic group-containing Si alkoxide compound (b-1), and the Si alkoxide compound (b-2) is as follows. As appropriate. For example, it is appropriately determined in consideration of the compounding ratio of Ti and Si in the metal oxide matrix so that a desired refractive index of the metal oxide matrix can be obtained. For example, the Ti / Si atm ratio may be 0.1 / 1.0 to 10 / 1.0.

  Further, the amount of the hydrophilic organic group-containing Si alkoxide compound (b-1) used may be appropriately determined from the viewpoint of relaxing the hydrophobicity of the glycol coordinated to the Ti alkoxide compound (a). . For example, the Si alkoxide compound (b-1) is preferably about 1 to 90 mol% and the Si alkoxide compound (b-2) is about 10 to 99 mol% based on the entire Si alkoxide compound to be used.

  The hydrolysis and polymerization reaction of the mixed alkoxide compound can be carried out under the same operation and conditions as in the known sol-gel method. For example, a predetermined proportion of the metal alkoxide compound raw material (the alkoxide compound (a) of Ti coordinated with the glycol, the alkoxide compounds (b-1) and (b-2) of Si, and other metals as necessary) The reaction can be carried out by dissolving the alkoxide compound) in a suitable good solvent as a homogeneous solution, dropping a suitable acid catalyst into 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, dioxane, tetrahydrofuran, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, acetylacetone and the like should not be used in the coordination step of glycol to the Ti alkoxide compound. 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 of the Ti alkoxide compound in which the coordination site is not satisfied is coordinated with these organic solvents. Position (or complex formation) is likely to occur. Therefore, it has been found that the obtained metal oxide has absorption for blue light.

  Accordingly, organic alcohols suitable for both the glycol coordination step and the sol-gel step include monoalcohols and monoalkyl ethers of dialcohols. Specific examples include monoalcohols such as methanol, ethanol, propanol, isopropanol, and butanol; and monoalkyl ethers of dialcohol such as 1-methoxy-2-propanol and ethylene glycol monomethyl ether (methyl cellosolve). What is necessary is just to select suitably from these. Or it can also be set as these mixed solvents. 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, the absorption of the metal oxide with respect 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.

  Before the hydrolysis, during hydrolysis or after hydrolysis, a photopolymerizable organic compound described later is mixed. 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.

  The polycondensation reaction of the metal oxide precursor mixed with the photopolymerizable compound is advanced to obtain a hologram recording material liquid in which the photopolymerizable compound is uniformly mixed in the sol-state metal oxide matrix. A film-like hologram recording material layer is obtained by applying a hologram recording material liquid on a substrate and further allowing solvent drying and sol-gel reaction to proceed. In this way, a hologram recording material layer in which the photopolymerizable compound is uniformly contained in the metal oxide matrix is produced.

  In this way, by subjecting the Ti alkoxide compound in a state in which the glycol is coordinated to the sol-gel reaction, it is inhibited that another coordination compound is coordinated to the Ti atom during the sol-gel reaction. The coloration of the resulting metal oxide matrix is greatly reduced.

  Further, in the obtained metal oxide matrix, a hydrophilic organic group is directly bonded to a part of Si through Si-C bond, thereby the metal oxide matrix and the photopolymerizable monomer. Can be compatible with the high compatibility of the photopolymerizable monomer in the matrix during recording.

  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.

Further, as the photopolymerizable compound, in order to further improve the compatibility with the metal oxide, a more hydrophilic polyethylene glycol unit:
− (CH ₂ CH ₂ O) p −
The thing which has is preferable. p represents the number of repeating units of ethylene oxide, the number of repeating units p is preferably 3 or more, p is more preferably 4 or more and 50 or less, and p is more preferably 5 or more and 30 or less. Glycol derivatives such as polyethylene glycol (meth) acrylate and polyethylene glycol di (meth) acrylate are preferred.

  The photopolymerizable compound having such a hydrophilic polyalkylene glycol unit has good compatibility with both the metal oxide matrix and the metal alkoxide compound and the multimer which is a partial condensate in the formation stage. Uniform dispersion in the oxide matrix is achieved.

  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 whole metal oxide. 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 preferably further contains a photopolymerization initiator corresponding to the wavelength of the recording light. When a photopolymerization initiator is contained, the 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, a dye that becomes a photosensitizer corresponding to the recording light wavelength may be contained. 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 3 to 50% by weight of the photo radical initiator, for example, about 10% by weight.

  In this manner, a hologram recording material layer in which the photopolymerizable organic 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 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.

  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.

  In a transmitted light reproduction type medium, a laser beam for reading is incident on the medium, the incident laser light is diffracted by a recorded signal of the hologram recording material layer, and the laser light transmitted through the medium is electrically converted by an image sensor. It is configured to convert to a signal. That is, in the transmitted light reproduction type medium, the laser beam to be detected is transmitted to the side opposite to the incident side of the reproduction laser beam to the medium. The transmitted light reproduction type medium usually has a configuration in which a recording material layer is sandwiched between two support substrates. In the optical system used, an image sensor for detecting transmitted laser light is provided on the side opposite to the incident side of reproduction laser light oscillated from a light source with a medium as a reference.

  Therefore, in the transmitted light reproduction type medium, the support substrate, the recording material layer, and any other layers are all made of a light transmissive material, and there is substantially no element that blocks the transmission of the reproduction laser light. Don't be. The support base is usually a rigid substrate made of glass or resin.

  On the other hand, in the reflected light reproduction type, a laser beam for reading is incident on a medium, and the incident laser beam is diffracted by a recorded signal of the hologram recording material layer, and then reflected by a reflecting film and reflected. Is converted into an electrical signal by the image sensor. That is, in the reflected light reproduction type medium, the laser light to be detected is reflected on the same side as the incident side of the reproduction laser light to the medium. The reflected light reproduction type medium is usually configured such that a recording material layer is provided on a support substrate positioned on the reproduction laser light incident side, and a reflection film and a support substrate are provided on the recording material layer. The optical system device used is provided with an image sensor for detecting reflected laser light on the same side as the incident side of the reproduction laser light oscillated from the light source with reference to the medium.

  Therefore, in the reflected light reproduction type medium, the layer positioned on the incident side of the reproduction laser beam from the reflective film of the support substrate, the recording material layer, and any other layer positioned on the incident side of the reproduction laser beam. Each is made of a translucent material, and there should be substantially no element that blocks incident and reflected reproduction laser light. The support base is usually a rigid substrate made of glass or resin, and the support base located on the reproduction laser light incident side needs to be translucent.

  In either the transmitted light reproduction type medium or the reflected light reproduction type medium, it is important that the hologram recording material layer has a high light transmittance of, for example, 50% or more at a wavelength of 405 nm. For example, when considering a layer (thickness: 100 μm) made only of a matrix material (metal oxide material), it is preferable to have a high light transmittance of 90% or more at a wavelength of 405 nm.

  The hologram recording material layer obtained as described above has a high blue laser transmittance. Therefore, even when the thickness of the recording material layer is 100 μm, in the case of the transmitted light reproduction type, a recording medium having a light transmittance of 50% or more, preferably 55% or more at a wavelength of 405 nm can be obtained or reflected. In the case of the optical reproduction type, a recording medium having a light reflectance of 25% or more, preferably 27.5% or more at a wavelength of 405 nm is obtained. In order to achieve holographic memory recording characteristics that ensure high multiplicity, a recording material layer having a thickness of 100 μm or more, preferably 200 μm or more is required. According to the present invention, for example, the recording material layer thickness is 1 mm. Even in this case, a light transmittance of 50% or more (transmitted light reproduction type) at a wavelength of 405 nm or a light reflectance of 25% or more (reflected light reproduction type) at a wavelength of 405 nm can be ensured.

  By using the hologram recording material layer, 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 a hologram recording layer made of the hologram recording material of the present invention is suitable not only for a system that records and reproduces by a green laser beam, but also for a system that records and reproduces by a blue laser beam having a wavelength of 350 to 450 nm. Can be used.

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

  First, the Si alkoxide compound used in each Example and Comparative Example is shown below. The underline is the non-hydrolyzable organic group of interest and indicates its (local) SP value.

Example 1
Diphenyldimethoxysilane
Ph ₂ -Si (OCH ₃ ) ₃ SP value: 21.15 (J / cm ³ ) ^0.5
Hydroxymethyltriethoxysilane
_{HOCH 2 -Si (OC 2 H 5} ) 3 SP ^{value: 36.49 (J / cm 3)} 0.5

(Example 2)
Diphenyldimethoxysilane
Ph ₂ -Si (OCH ₃ ) ₃ SP value: 21.15 (J / cm ³ ) ^0.5
N- (3-Triethoxysilylpropyl) gluconamide
(C ₂ H ₅ O) ₃ Si— CH ₂ CH ₂ CH ₂ NHCO— [CH (OH)] ₅ —H SP value: 36.14 (J / cm ³ ) ^0.5

(Comparative Examples 1, 3, 4)
Diphenyldimethoxysilane
Ph ₂ -Si (OCH ₃ ) ₃ SP value: 21.15 (J / cm ³ ) ^0.5

(Comparative Example 2)
Diphenyldimethoxysilane
Ph ₂ -Si (OCH ₃ ) ₃ SP value: 21.15 (J / cm ³ ) ^0.5
Cyclohexylmethyldimethoxysilane
C ₆ H ₁₁ —Si (CH ₃ ) (OCH ₃ ) ₂ SP value: 17.48 (J / cm ³ ) ^0.5

[Example 1]
(Synthesis of matrix material)
Tetrabutoxy titanium (Ti (OBu) ₄ , high-purity chemical) 3.65 g and 2-ethyl-1,3-hexanediol (Tokyo Kasei) 3.1 g in 1 mL of n-butanol solvent at room temperature. Mix and stir for 10 minutes. Ti (OBu) ₄ / 2-ethyl-1,3-hexanediol = 1/2 (molar ratio). To this reaction solution, 1.96 g of diphenyldimethoxysilane (manufactured by Shin-Etsu Chemical) and 0.52 g of hydroxymethyltriethoxysilane were added to obtain a metal alkoxide solution. Ti / Si = 1/1 (molar ratio).
A solution consisting of 0.2 mL of water, 0.08 mL of 2N hydrochloric acid aqueous solution, and 1 mL of solvent ethanol was added dropwise to the metal alkoxide solution at room temperature while stirring, and stirring was continued for 30 minutes to perform a hydrolysis reaction and a condensation reaction. 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 2, as a photosensitizer 4-Diethyl-9H-thioxanthen-9-one 0.3 part by weight was added to obtain a 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, and is shielded from light Then, the sol-gel reaction was sufficiently advanced for 1 hour to obtain a hologram recording material solution.

  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 72 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 300 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 allowed to stand for 1 month in an environment of room temperature and a relative humidity of 60%, and then the following characteristic evaluation was performed. The same applies to Example 2 and Comparative Example 1.

  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. 45-degree (deg) polarized light is extracted from the expanded beam through the mirror (108) and the half-wave plate (109), and the S wave / P wave is set to 1/1 by the polarization beam splitter (110). Divided. 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 was recorded by rotating the sample (11) in the horizontal direction and multiplexing (angle multiplexing: sample angle -21 ° to + 21 °, angular interval 0.6 °). The multiplicity was 71. During recording, the iris diaphragm (114) and (117) were exposed with a diameter of 4 mm. The position at which the sample (11) plane is 90 ° with respect to the bisector (not shown) of the angle θ formed by the two light beams was defined as the sample angle ± 0 °.

  After the hologram recording, in order to react the remaining unreacted components, the entire surface of the sample (11) was irradiated with sufficient light with a blue LED having a wavelength of 400 nm. At this time, exposure was performed through an acrylic resin diffusion plate having a transmittance of 80% so that the irradiated light did not have coherency (referred to as post-cure). During playback, the shutter (121) is shielded from light, the iris diaphragm (117) is 1 mm in diameter and only one beam is irradiated, and the sample (11) is continuously rotated horizontally from -23 ° to + 23 °. 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 20.2 (a value converted when the thickness of the hologram recording material layer was 1 mm).
The light transmittance of the medium (recording layer thickness: 300 μm) at 405 nm before recording exposure (initial stage) was 79.0%. The light transmittance of the medium at 405 nm after recording (after post-cure with a blue LED) was 79%, and the initial light transmittance was maintained.

[Example 2]
In the synthesis of the matrix material, a sol solution was obtained in the same manner as in Example 1 except that the Si alkoxide used was replaced with 2.0 g of diphenyldimethoxysilane and 1.0 g of N- (3-triethoxysilylpropyl) gluconamide. Got. Ti / Si = 1/1 (molar ratio). Using the sol solution, a hologram recording medium was obtained in the same manner as in Example 1.

  The obtained medium was allowed to stand in an environment of room temperature and relative humidity of 60% for 1 month and then evaluated for characteristics in the same manner as in Example 1. As a result, the dynamic range: M / # was 19.6, before recording exposure. The light transmittance of the medium (recording layer thickness: 300 μm) at 405 nm (initial) was 85.0%, and the light transmittance of the medium at 405 nm after recording was 82%.

[Comparative Example 1]
In the synthesis of the matrix material, a sol solution was obtained in the same manner as in Example 1 except that the Si alkoxide used was only 2.2 g of diphenyldimethoxysilane. Ti / Si = 1.2 / 1 (molar ratio). Using the sol solution, a hologram recording medium was obtained in the same manner as in Example 1.

  The obtained medium was allowed to stand in an environment at room temperature and a relative humidity of 60% for 1 month, and was then evaluated in the same manner as in Example 1. As a result, the dynamic range: M / # was 18.6, before recording exposure. The light transmittance of the medium (recording layer thickness: 300 μm) at 405 nm (initial) was 55.0%, and the light transmittance of the medium at 405 nm after recording was 36%.

  The recording layer immediately after production of the hologram recording medium was transparent, but the entire recording layer gradually became slightly cloudy while being left in an environment of room temperature and 60% relative humidity for 1 month. . Furthermore, the exposure spot became clouded significantly by recording. Therefore, the light transmittance was significantly reduced before and after recording as compared with Examples 1 and 2.

[Comparative Example 2]
In the synthesis of the matrix material, a sol solution was obtained in the same manner as in Example 1 except that the Si alkoxide used was changed to 2.1 g of diphenyldimethoxysilane and 0.4 g of cyclohexylmethyldimethoxysilane. Ti / Si = 1/1 (molar ratio). Using the sol solution, a hologram recording medium was obtained in the same manner as in Example 1.

  Remarkable irregularities were formed on the surface of the recording layer after heating and drying during the production of the recording medium, and the entire recording layer was clouded. It was impossible to evaluate the characteristics of the recording layer.

[Comparative Example 3: Ti in which glycol is not coordinated]
(Synthesis of matrix material)
7.2 g of titanium butoxide decamer (B-10 manufactured by Nippon Soda Co., Ltd.) represented by the following formula and 7.8 g of diphenyldimethoxysilane were mixed at room temperature in 6 mL of tetrahydrofuran solvent to obtain a metal alkoxide solution. Ti / Si = 1/1 (molar ratio).
A solution consisting of 0.9 mL of water, 0.36 mL of 2N aqueous hydrochloric acid, and 3 mL of tetrahydrofuran was dropped into the alkoxide solution at room temperature while stirring, and stirring was continued for 1 hour to perform a hydrolysis reaction and a condensation reaction. In this way, a sol solution was obtained.

_{C 4 H 9 - [OTi (} OC 4 H 9) 2] L -OC 4 H 9 (L = 10)

  Using the sol solution, a hologram recording medium was obtained in the same manner as in Example 1.

  When the characteristics of the medium immediately after production were evaluated in the same manner as in Example 1, the dynamic range M / # was 18.1 (value converted when the thickness of the hologram recording material layer was 1 mm). . However, the light transmittance of the medium (recording layer thickness: 300 μm) at 405 nm before recording exposure (initial) was 35%. The light transmittance of the medium at 405 nm after recording decreased to 1%.

[Comparative Example 4: Ti in which glycol is not coordinated]
(Synthesis of matrix material)
Tetrabutoxytitanium (Ti (OBu) ₄ , high-purity chemical) 3.65 g and ethyl acetoacetate (EtAcAc, Tokyo Chemical Industry) 2.76 g were mixed in 1 mL of n-butanol solvent at room temperature for 10 minutes. Stir. Ti (OBu) ₄ / EtAcAc = 1/2 (molar ratio). To this reaction solution, 2.6 g of diphenyldimethoxysilane (manufactured by Shin-Etsu Chemical) was added to obtain a metal alkoxide solution. Ti / Si = 1/1 (molar ratio).
A solution consisting of 0.2 mL of water, 0.08 mL of 2N hydrochloric acid aqueous solution, and 1 mL of solvent ethanol was added dropwise to the metal alkoxide solution at room temperature while stirring, and stirring was continued for 30 minutes to perform a hydrolysis reaction and a condensation reaction. In this way, a sol solution was obtained.

  Using the sol solution, a hologram recording medium was obtained in the same manner as in Example 1.

  However, the light transmittance of the medium immediately after fabrication (recording layer thickness: 300 μm) at 405 nm before recording exposure (initial stage) is 15%, and cannot be used as a recording medium.

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 (9)

A hologram recording material comprising a metal oxide matrix and a photopolymerizable compound,
The metal oxide matrix contains at least Ti and Si as metal elements, and glycol is coordinated to Ti, and a hydrophilic organic group is partly included in Si through Si—C bonds. Hologram recording material that is directly bonded to.   The hologram recording material according to claim 1, wherein the glycol is a glycol other than a seminar diol. The glycol has the general formula (I):

(In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ may be the same or different and each represents a hydrogen atom or an alkyl group, provided that R ₁ , R ₂ , R ₃ , The total number of carbon atoms contained in R ₄ , R ₅ and R ₆ is 0-5.)
The hologram recording material of Claim 1 or 2 represented by these. The hydrophilic organic group has a solubility parameter value (SP value) determined by Fedors' estimation method of 21.5 (J / cm ³ ) ^0.5 or more, according to any one of claims 1 to 3. The hologram recording material according to Item.   The aromatic hydrocarbon group is directly bonded to the Si via a Si-C bond in at least a part of Si other than Si to which the hydrophilic organic group is bonded. The hologram recording material according to any one of the above. The photopolymerizable compound is a polyethylene glycol unit represented by the following formula:
− (CH ₂ CH ₂ O) p −
(Where p represents the number of repeating units of ethylene oxide)
The hologram recording material according to any one of claims 1 to 5, which is a radically polymerizable compound having   The hologram recording material according to claim 6, wherein the repeating unit number p is 3 or more.   Furthermore, the hologram recording material of any one of Claims 1-7 containing a photoinitiator.   A hologram recording medium having a hologram recording layer made of the hologram recording material according to claim 1.

Images