JP4466141B2 - Holographic recording composition, holographic recording medium, holographic recording method, and holographic information medium - Google Patents

Description

  The present invention relates to a holographic recording medium capable of large capacity and high-speed transfer, and further relates to a holographic recording composition suitable for the medium, a holographic recording method, and a holographic information medium on which information is recorded. is there.

  In recent years, the exchange of high-speed and large-capacity data due to the spread of the Internet and broadbandization has increased, and the capacity of data stored in each affiliated organization has expanded rapidly due to the expansion of e-government promoted by governments in each country. Yes. Furthermore, it is expected that high-capacity recording media will be required in the future due to the spread of high-definition television broadcasting and the spread of terrestrial digital. Among them, next-generation optical recording such as Blu-ray disc, HD, DVD, etc. The media is expected to spread in the future. However, for the next generation of recording media, various methods have been proposed, but they are still not present.

  Among these next-generation recording media, page-type memory systems, particularly holographic recording, have been proposed as an alternative to conventional memory devices, and are high-capacity and high-speed transfer capable of random access. That has attracted attention in recent years. Hans J.H. Coufal et al., “Holographic Data Storage (Springer Series in Optical Sciences, Vol. 76)” (Springer-Verlag GmbH / Co. KG, August 2000) provides a review of holographic recording.

  As a recording method in this holographic recording, for example, a recording method using a holographic recording medium in which a transparent base material is disposed on both sides of the holographic recording layer (see, for example, Patent Document 1), or holographic recording. A recording method using a holographic recording medium including a reflective surface arranged on one side of a layer (for example, see Patent Document 2) has been proposed.

  Such a holographic recording medium records information by changing the refractive index in the holographic recording layer in the medium by holographic exposure, and reads the change in the refractive index in the recorded medium. This is based on the principle of reproducing information, and as this holographic recording layer, a material using an inorganic material (for example, see Patent Document 3), a material using a compound that undergoes structural isomerization with light (for example, , Patent Document 4), or materials utilizing diffusion polymerization of photopolymers (see, for example, Patent Document 5). Among these, in the material using the photopolymer described in Patent Document 5, a volatile solvent is used when preparing the recording composition, so the thickness of the material is limited to about 150 μm at the maximum. Has been. Furthermore, the 4-10% volume shrinkage caused by the polymerization had an adverse effect on the reliability in reproducing the recorded information.

  In order to improve the above-described drawbacks, a holographic recording composition (for example, see Patent Document 6) using a cationic polymerization that is solvent-free and has relatively little system shrinkage has been proposed. However, in this recording composition, since the liquid substance other than the monomer that causes photocationic polymerization, the island-shaped portion formed by photopolymerization of the monomer in the recording layer by holographic exposure may move. Or the volume of the liquid material expands due to a change in the environmental temperature in the apparatus.

  In order to remedy such drawbacks, a composition in which a binder is formed after the formation of the media in order to retain the radically polymerizable monomer before the exposure is used for recording in holographic exposure (for example, patents) Reference 7) is proposed, and by using such a composition, the film thickness of the holographic recording layer can be increased and the volume shrinkage can be reduced, but it cannot be said that it is still sufficient. .

On the other hand, when holographic recording is performed on a holographic recording medium, exposure with low energy is essential for improving the recording speed. In order to improve the recording speed, in other words, the recording sensitivity, it is important to select and combine the radical polymerizable monomer, binder forming compound, sensitizing dye and radical initiator used. For example, a photosensitive composition for hologram recording using an isocyanate compound as a binder-forming compound (see, for example, Patent Documents 8 and 9) has been proposed, but it is still not sufficient.
US Pat. No. 5,719,691 JP 2002-123949 A British Patent No. 9,929,953 JP 10-340479 A U.S. Pat. No. 4,942,112 US Pat. No. 5,759,721 US Pat. No. 6,103,454 US Patent Application Publication No. 2003-44691 US Patent Application Publication No. 2003-87104

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-contrast holographic recording medium with high sensitivity, low volume shrinkage, and holographic recording composition for the medium. It is an object of the present invention to provide a holographic recording medium and a holographic recording medium with improved storage stability.

  The above object of the present invention has been achieved by the following constitutions.

（式中、Ｄｙｅ ^＋ はカチオン性色素を表し、Ｒ _１ 〜Ｒ _４ は各々置換または非置換のアルキル基、アリール基、アラルキル基、アルケニル基、アルキニル基、複素環基またはシアノ基を表し、またＲ _１ 〜Ｒ _４ は各々２個以上が互いに結合して環を形成してもよい。）
（８）
第一の基材と第二の基材の間にホログラフィック記録層が挟持されたホログラフィック記録メディアにおいて、該ホログラフィック記録層がバインダー形成化合物、エチレン性不飽和結合を有する化合物、及び前記エチレン性不飽和結合を有する化合物の重合反応を開始することのできる光重合開始剤を含む層で構成され、且つ前記バインダー形成化合物としてイソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物を含有し、該イソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物が、バインダー形成化合物として含有されるイソシアネート基を有する化合物全体に対して５質量％以上１００質量％以下であることを特徴とするホログラフィック記録メディア。
（９）
前記第一の基材の厚みをｄ１、第二基材の厚みをｄ２とし、ホログラフィック記録層の厚みをＤｈとした際に、０．１５≦Ｄｈ／（ｄ１＋ｄ２）≦２．０の関係を満たすことを特徴とする８に記載のホログラフィック記録メディア。
（１０）
前記ホログラフィック記録層の厚みＤｈが２００μｍ以上、２．０ｍｍ以下であることを特徴とする９に記載のホログラフィック記録メディア。
（１１）
前記第一の基材の厚みｄ１と第二基材の厚みｄ２との関係がｄ１≦ｄ２であることを特徴とする９または１０に記載のホログラフィック記録メディア。
（１２）
前記第一の基材が透明であり、ホログラフィック記録層が積層された面とは反対の面に反射防止処理がなされていることを特徴とする８〜１１のいずれか１項に記載のホログラフィック記録メディア。
（１３）
前記第一の基材の材質がガラスであることを特徴とする８〜１２のいずれか１項に記載のホログラフィック記録メディア。
（１４）
前記第二の基材のホログラフィック記録層が積層される面あるいはその反対面に反射率が７０％以上の反射層が積層されていることを特徴とする８〜１３のいずれか１項に記載のホログラフィック記録メディア。
（１５）
８〜１４のいずれか１項に記載のホログラフィック記録メディアにおいて、形状がディスク状であることを特徴とするホログラフィック記録メディア。
（１６）
８〜１４のいずれか１項に記載のホログラフィック記録メディアにおいて、形状がカード状であることを特徴とするホログラフィック記録メディア。
（１７）
第一の基材と第二の基材の間にホログラフィック記録層が挟持され、該ホログラフィック記録層としてバインダー形成化合物、エチレン性不飽和結合を有する化合物、及び前記エチレン性不飽和結合を有する化合物の重合反応を開始することのできる光重合開始剤を少なくとも含有し、前記バインダー形成化合物としてイソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物、及び分子内に２個以上の水酸基を有する化合物を含有し、該イソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物が、バインダー形成化合物として含有されるイソシアネート基を有する化合物全体に対して５質量％以上１００質量％以下である記録層が積層されたホログラフィック記録メディアにホログラフィック記録する方法において、ホログラフィック露光の前にバインダー形成化合物同士を反応させバインダーを形成させた後に、記録したい情報を基にしたホログラフィック露光を行い、光重合開始剤を活性化させ、この活性種によりエチレン性不飽和結合を有する化合物をホログラフィック記録層内で拡散重合させることによりホログラフィック記録メディアに情報を記録することを特徴とするホログラフィック記録方法。
（１８）
前記ホログラフィック記録メディアに情報を記録した後に、更にホログラフィック記録メディア全体に熱及び光照射を行うことにより記録された情報を安定化させることを特徴とする１７に記載のホログラフィック記録方法。
（１９）
第一の基材と第二の基材の間にホログラフィック記録層が挟持され、該ホログラフィック記録層としてバインダー形成化合物、エチレン性不飽和結合を有する化合物、及び前記エチレン性不飽和結合を有する化合物の重合反応を開始することのできる光重合開始剤を少なくとも含有し、前記バインダー形成化合物としてイソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物を含有し、該イソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物が、バインダー形成化合物として含有されるイソシアネート基を有する化合物全体に対して５質量％以上１００質量％以下であり、更に分子内に２個以上の水酸基を有する化合物を含有する記録層が積層されたホログラフィック記録メディアにホログラフィック記録する方法において、記録したい情報を基にしたホログラフィック露光を行い、光重合開始剤を活性化させ、この活性種によりエチレン性不飽和結合を有する化合物を拡散重合させることによりホログラフィック記録メディアに情報を記録し、ホログラフィック記録メディアへの情報記録が終了した後に、更にホログラフィック記録メディア全体に熱及び光照射を行うことにより記録された情報を安定化させることを特徴とするホログラフィック記録方法。
（２０）
第一の基材と第二の基材の間にホログラフィック記録層が挟持され、該ホログラフィック記録層が、イソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物を含有し、該イソシアネート基の占める割合が化合物中３０質量％以上６５質量％以下である分子内に３個以上のイソシアネート基を有する化合物が、バインダー形成化合物として含有されるイソシアネート基を有する化合物全体に対して５質量％以上１００質量％以下であり、更に分子内に２個以上の水酸基を有する化合物との反応から形成されたウレタン化合物を主成分とする領域と、エチレン性不飽和結合を有する合物をラジカル重合させて形成したラジカル重合体を主成分とする領域とを有することを特徴とするホログラフィック情報メディア。 ( 1 )
A holographic recording composition comprising at least a binder-forming compound, a compound having an ethylenically unsaturated bond, and a photopolymerization initiator capable of initiating a polymerization reaction of the compound having an ethylenically unsaturated bond. As a forming compound, a compound having 3 or more isocyanate groups in the molecule in which the proportion of the isocyanate group is 30% by mass or more and 65% by mass or less in the compound is contained , and the proportion of the isocyanate group is 30% by mass in the compound above 65 wt% or less is within the molecular compound having three or more isocyanate groups, the der Rukoto 100 mass% to 5 mass% or less with respect to the entire compound having an isocyanate group contained as a binder forming compounds A holographic recording composition.
(2)
2. The holo according to 1, wherein the molecular weight of the compound having 3 or more isocyanate groups in the molecule in which the proportion of the isocyanate group is 30% by mass to 65% by mass in the compound is 200 to 500 Graphic recording composition.
(3)
The composition for holographic recording according to 1 or 2, further comprising a compound having two or more hydroxyl groups in the molecule as the binder-forming compound.
(4)
4. The composition for holographic recording according to 3, wherein the molecular weight of the compound having two or more hydroxyl groups in the molecule is 100 or more and 2000 or less.
(5)
The composition for holographic recording according to any one of 1 to 4, wherein the compound having an ethylenically unsaturated bond contains a compound having a (meth) acryloyl group in the molecule.
(6)
The composition for holographic recording according to any one of 1 to 5, wherein the compound having an ethylenically unsaturated bond in the molecule contains a compound having a refractive index of 1.55 or more.
(7)
Any one of 1 to 6, wherein the photopolymerization initiator is at least one compound selected from a bisimidazole compound, a metal π complex, and a compound represented by the following general formula (1). The composition for holographic recording as described in the paragraph.

( Wherein Dye ⁺ represents a cationic dye, R _{1 to} R ₄ each represents a substituted or unsubstituted alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, heterocyclic group or cyano group, and R _{2 to} R ₄ may be bonded to each other to form a ring.
(8)
In a holographic recording medium in which a holographic recording layer is sandwiched between a first substrate and a second substrate, the holographic recording layer has a binder-forming compound, a compound having an ethylenically unsaturated bond, and the ethylene Composed of a layer containing a photopolymerization initiator capable of initiating a polymerization reaction of a compound having a polymerizable unsaturated bond, and the proportion of the isocyanate group as the binder-forming compound is 30% by mass or more and 65% by mass or less in the compound A compound having a compound having three or more isocyanate groups in a certain molecule and having a proportion of the isocyanate group of 30% by mass or more and 65% by mass or less in the compound having three or more isocyanate groups in the molecule, 5% by mass based on the whole compound having an isocyanate group contained as a binder-forming compound The holographic recording medium, characterized in that at the upper 100 mass% or less.
(9)
When the thickness of the first substrate is d1, the thickness of the second substrate is d2, and the thickness of the holographic recording layer is Dh, the relationship of 0.15 ≦ Dh / (d1 + d2) ≦ 2.0 is satisfied. 9. The holographic recording medium according to 8, wherein the holographic recording medium is satisfied.
(10)
10. The holographic recording medium according to 9, wherein a thickness Dh of the holographic recording layer is 200 μm or more and 2.0 mm or less.
(11)
The holographic recording medium according to 9 or 10, wherein a relationship between the thickness d1 of the first base material and the thickness d2 of the second base material is d1 ≦ d2.
(12)
The horo according to any one of claims 8 to 11, wherein the first base material is transparent, and an antireflection treatment is performed on a surface opposite to the surface on which the holographic recording layer is laminated. Graphic recording media.
(13)
The holographic recording medium according to any one of 8 to 12, wherein a material of the first base material is glass.
(14)
The reflective layer having a reflectance of 70% or more is laminated on the surface on which the holographic recording layer of the second substrate is laminated or on the opposite surface thereof. Holographic recording media.
(15)
The holographic recording medium according to any one of 8 to 14, wherein the holographic recording medium has a disk shape.
(16)
The holographic recording medium according to any one of 8 to 14, wherein the holographic recording medium has a card shape.
(17)
A holographic recording layer is sandwiched between a first substrate and a second substrate, and the holographic recording layer has a binder-forming compound, a compound having an ethylenically unsaturated bond, and the ethylenically unsaturated bond It contains at least a photopolymerization initiator capable of initiating a polymerization reaction of the compound, and the proportion of the isocyanate group as the binder-forming compound is 30% by mass or more and 65% by mass or less in the molecule. A compound having a group and a compound having two or more hydroxyl groups in the molecule, and the proportion of the isocyanate group is 30% by mass to 65% by mass in the compound; 5 for the entire compound having an isocyanate group contained as a binder-forming compound. Information to be recorded after forming a binder by reacting binder forming compounds with each other before holographic exposure in a method for holographic recording on a holographic recording medium having a recording layer laminated in an amount of 100% by mass or less. The photopolymerization initiator is activated by holographic exposure based on the holographic recording medium, and the active species is used to diffusely polymerize a compound having an ethylenically unsaturated bond in the holographic recording layer, thereby transferring information to the holographic recording medium. A holographic recording method characterized by recording.
(18)
18. The holographic recording method according to 17, wherein after the information is recorded on the holographic recording medium, the recorded information is further stabilized by performing heat and light irradiation on the entire holographic recording medium.
(19)
A holographic recording layer is sandwiched between a first substrate and a second substrate, and the holographic recording layer has a binder-forming compound, a compound having an ethylenically unsaturated bond, and the ethylenically unsaturated bond It contains at least a photopolymerization initiator capable of initiating a polymerization reaction of the compound, and the proportion of the isocyanate group as the binder-forming compound is 30% by mass or more and 65% by mass or less in the molecule. An isocyanate group containing a compound having a group, and a compound having 3 or more isocyanate groups in the molecule in which the proportion of the isocyanate group is 30% by mass to 65% by mass in the compound is contained as a binder-forming compound 5% by mass to 100% by mass with respect to the total compound having In a holographic recording method on a holographic recording medium in which a recording layer containing a compound having two or more hydroxyl groups is laminated, holographic exposure based on information to be recorded is performed to activate a photopolymerization initiator. The compound having an ethylenically unsaturated bond is diffusion-polymerized by the active species to record information on the holographic recording medium. After the information recording on the holographic recording medium is completed, the entire holographic recording medium is further heated. And a holographic recording method comprising stabilizing information recorded by light irradiation.
(20)
A holographic recording layer is sandwiched between the first base material and the second base material, and the holographic recording layer has a proportion of 30% by mass to 65% by mass of the isocyanate group in the compound. A compound having three or more isocyanate groups in the molecule containing a compound having three or more isocyanate groups, and the proportion of the isocyanate groups being 30% by mass or more and 65% by mass or less in the compound is a binder-forming compound. The region containing 5% by mass or more and 100% by mass or less of the entire compound having an isocyanate group, and mainly comprising a urethane compound formed by a reaction with a compound having two or more hydroxyl groups in the molecule. And a region mainly composed of a radical polymer formed by radical polymerization of a compound having an ethylenically unsaturated bond. Holographic information media to be characterized.

  According to the present invention, a holographic recording medium having high sensitivity, low volume shrinkage, and high contrast, a holographic recording composition for the medium, a holographic recording method, and holographic recording improved storage stability. Holographic information media could be provided.

  Hereinafter, the holographic recording composition, holographic recording medium, holographic recording method and holographic information medium of the present invention will be described in detail.

The composition for holographic recording used in the recording layer of the holographic recording medium of the present invention includes a binder-forming compound, a compound having an ethylenically unsaturated bond, and a polymerization reaction of the compound having the ethylenically unsaturated bond. A compound having at least three photopolymerization initiators and having three or more isocyanate groups in the molecule in which the proportion of isocyanate groups as the binder-forming compound is 30% by mass to 65% by mass in the compound. The entire compound having an isocyanate group that is contained as a binder-forming compound, at least a compound having 3 or more isocyanate groups in a molecule that contains at least 30% by mass to 65% by mass of the isocyanate group. der 5 wt% to 100 wt% with respect to It is characterized in that. By using such an isocyanate compound, the shrinkage of the recording medium before and after the holographic exposure described in detail later can be prevented.

  The compound having three or more isocyanate groups in the molecule in which the proportion of the isocyanate group added as an essential component in the present invention is 30% by mass or more and 65% by mass or less in the compound is a compound satisfying this condition. For example, 1,8-diisocyanate-4-isocyanatomethyl-octane (NCO content: 50.2 mass%, molecular weight: 251.3), 2-isocyanatoethyl-2,6- Diisocyanate caproate (NCO content: 49.8 mass%, molecular weight: 253.2), benzene-1,3,5-triisocyanate (NCO content: 62.7 mass%, molecular weight: 201.1), 1-methylbenzene-2,4,6-triisocyanate (NCO content: 58.6% by mass, molecular weight: 215.2), 1,3, -Trimethylbenzene-2,4,6-triisocyanate (NCO content: 51.8 mass%, molecular weight: 243.2), diphenylmethane-2,4,4'-triisocyanate (NCO content: 43.3 mass) %, Molecular weight: 291.3), triphenylmethane-4,4 ′, 4 ″ -triisocyanate (NCO content: 34.3 mass%, molecular weight: 367.4), bis (isocyanatotolyl) phenylmethane ( NCO content: 42.6% by mass, molecular weight: 291.3).

  Incidentally, a compound having three or more isocyanate groups in the molecule in which the proportion of the isocyanate group is 30% by mass or more and 65% by mass or less in the compound is used in the recording media before and after the holographic exposure described in detail later. It is preferable because shrinkage can be further prevented, and a molecular weight of 200 or more and 500 or less is more preferable because the solubility and compatibility of other essential components and additives described later are excellent.

  The binder-forming compound according to the present invention includes other isocyanate groups in addition to a compound having 3 or more isocyanate groups in the molecule in which the proportion of the above-described essential component isocyanate group is 30% by mass to 65% by mass in the compound. A compound containing a group may be used in combination, and as such a compound having an isocyanate group, a compound having at least two isocyanate groups in the molecule is preferable. For example, dimethylene diisocyanate, tetramethylene diisocyanate, hexane Methylene diisocyanate, 2,2-dimethylpentane diisocyanate, 2,2,4-trimethylpentane diisocyanate, decane diisocyanate, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,2 -Dimethyl Cyclohexane diisocyanate, ω, ω-diisocyanate-1,4-diethylbenzene, isophorone diisocyanate, 1-methylcyclohexyl-2,4-diisocyanate, ω, ω'-diisocyanate-1,5-dimethylnaphthalene, ω, ω'-diisocyanate- n-propylbiphenyl, 1,3-phenylene diisocyanate, 1-methylbenzene-2,4-diisocyanate, 1,3-dimethylbenzene-2,6-diisocyanate, naphthalene-1,4-diisocyanate, 1,1'-dinaphthyl -2,2'-diisocyanate, biphenyl-2,4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, 2,2'-dimethyldiphenyl meta 4,4'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 3,3'-dimethoxydiphenylmethane-4,4'-diisocyanate, 4,4'-diethoxydiphenylmethane-4,4'-diisocyanate, Examples include tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, tetramethylene xylylene diisocyanate, and dimer or trimer adducts of each of the above isocyanate compounds (for example, hexamethylene diisocyanate). 2 mol adduct, 3 mol hexamethylene diisocyanate adduct, 2 mol 2,4-tolylene diisocyanate adduct, 3 mol 2,4-tolylene diisocyanate, etc.) Adducts of two or more different isocyanates selected from each other, and these isocyanates and divalent or trivalent polyalcohols (eg, diethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolpropane) Etc.) (for example, adducts of tolylene diisocyanate and trimethylolpropane, adducts of hexamethylene diisocyanate and trimethylolpropane, etc.). In addition, you may use these isocyanate compounds individually by 1 type or in combination of 2 or more types.

  In addition, the compound which has 3 or more isocyanate groups in the molecule | numerator whose ratio for which the isocyanate group which is an essential component which concerns on this invention accounts is 30 to 65 mass% in a compound is with respect to the whole compound which has an isocyanate group. It is preferable to add in the range of 5 mass% or more and 100 mass% or less. Further, in the above-described isocyanate compound, all information is recorded on a holographic recording medium in which a recording layer composed of a holographic recording composition described in detail later is laminated, and the holographic information medium used in a state where the recording is completed As with CDs and DVDs, there is a possibility that the ambient temperature under the fluorescent lamp, the window side, or the environment is varied. Accordingly, those which suppress the coloring of the recording layer under various conditions are preferable, and in order to suppress the coloring as described above, an aliphatic isocyanate compound is more preferable among the above-mentioned compounds.

  In the present invention, the binder may be formed by self-crosslinking of the compound having an isocyanate group, which is an essential component described above. However, in order to perform binder formation under mild conditions, It is preferable to form a binder by a crosslinking reaction with a compound having a functional group that reacts with an isocyanate group in the molecule.

  Examples of the compound capable of reacting with such an isocyanate compound include a compound having a hydroxyl group in the molecule, a compound having a primary or secondary amino group, and a compound having an enamine structure. However, in order to record all information on a holographic recording medium in which a recording layer composed of a holographic recording composition described in detail later is laminated, and to suppress coloring of the holographic information medium used in the state where the recording is completed. Among these compounds, a compound having a hydroxyl group is preferable as a compound capable of reacting with an isocyanate compound, and a compound having two or more aliphatic alcoholic hydroxyl groups in the molecule is more preferable.

  Examples of the compound having two or more alcoholic hydroxyl groups in the molecule include, for example, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 2,2-dimethyl-1,3- Propanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-butanediol, 1,4-butanediol, polytetramethylene glycol, 1,5-pentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2,5- Dimethyl-2,5-hexanediol, 1,10-decanedi , 1,4-cyclohexanediol, glycerin, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol and the like. Examples of the compound having at least one compound include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and polytetramethylene glycol modified with a divalent alcohol. It is done. In addition, the compound which has 2 or more of these alcoholic hydroxyl groups in a molecule | numerator may be used individually by 1 type or in combination of 2 or more types.

  The molecular weight of a compound having two or more aliphatic alcoholic hydroxyl groups in the molecule is the volatility of the compound itself, compatibility with a compound having an ethylenically unsaturated bond, which will be described later, or a photopolymerization initiator, and dissolution. In view of the properties, it is usually preferable that the molecular weight is 100 or more and 2000 or less, and the addition amount of the compound having two or more aliphatic alcoholic hydroxyl groups in the molecule is the above-mentioned essential isocyanate compound The number of isocyanate groups in the composition for holographic recording possessed by the compound having an isocyanate group is N [mol], and the alcoholic hydroxyl group is a holographic compound. When the number of moles of hydroxyl groups in the recording composition is M [mol], the range of 0.2 ≦ N / M ≦ 3.0 is usually satisfied. And it is preferably a more preferred in terms of 0.5 ≦ N / M ≦ 2.0, more control of preferably 0.7 ≦ N / M ≦ 1.5 range compatibility to or crosslinking reaction.

  Furthermore, in the present invention, when a urethane bond is formed by reacting the above-mentioned compound having an isocyanate group and a compound having two or more alcoholic hydroxyl groups in the molecule to form a urethane bond, a urethane-forming catalyst is used. It is preferable to add known organometallic compounds such as tin and lead.

  As the compound having an ethylenically unsaturated bond according to the present invention, for example, a styrene derivative, a compound having an allyl group, or an unsaturated olefin can be used without particular limitation as long as the object of the present invention is not impaired. In the case of considering adhesion with the base material and compatibility with the binder-forming compound, a compound having an acyloxy group or an acylamide group in the molecule is preferable, and from the viewpoint of steric hindrance during radical polymerization. A compound having a (meth) acryloyl group is more preferable. In addition, the (meth) acryloyl group said by this invention represents an acryloyl group or a methacryloyl group.

  In the present invention, for the binder formed from the above-mentioned binder-forming compound, in order to more significantly have a refractive index difference from a polymer of a compound having an ethylenically unsaturated bond obtained by diffusion polymerization, As the refractive index of the compound having an ethylenically unsaturated bond, it is preferable to use a higher or lower refractive index than the binder-forming compound. In particular, when a compound having a refractive index of the binder-forming compound of around 1.50 is used, a compound having an ethylenically unsaturated bond is preferably a compound having a refractive index of 1.55 or higher. Since the polymer of the compound which has is obtained, it is preferable.

  Such a compound having a (meth) acryloyl group having a refractive index of 1.55 or more generally has a hetero atom such as nitrogen, oxygen, sulfur and phosphorus, a halogen atom such as chlorine, bromine and iodine in the molecule, or Examples of the compound having two or more aromatic rings include paracumylphenoxyethylene glycol acrylate, paracumylphenoxyethylene glycol methacrylate, hydroxyethylated o-phenylphenol acrylate, and hydroxyethyl. Β-naphthol acrylate, tribromomophenyl acrylate, tribromomophenyl methacrylate, triiodophenyl methacrylate, polyethylene oxide modified tetrabromobisphenol A diacrylate, polyethylene oxide Tetrabromobisphenol A dimethacrylate, bis (4-methacryloylthiophenyl) sulfide, compounds having a fluorene skeleton described in JP-A-6-301322, JP-A-2000-344716, JP-A-2003-29604, etc. And so on.

  Further, when preparing a holographic recording composition within a range that does not hinder the purpose of providing a refractive index difference between a binder formed from a binder-forming compound and a diffusion polymer of a compound having an ethylenically unsaturated bond. In order to adjust the compatibility and viscosity of the polymer and to control diffusion polymerization during holographic exposure, a compound having a (meth) acryloyl group having a refractive index of less than 1.55 may be added. Examples of the compound having a (meth) acryloyl group include, for example, a compound having one (meth) acryloyl group, substituted or unsubstituted phenol, (meth) acrylates of nonylphenol and 2-ethylhexanol, and alkylenes of these alcohols. Examples thereof include (meth) acrylates of oxide adducts.

  Examples of the compound having two (meth) acryloyl groups include substituted or unsubstituted bisphenol A, bisphenol F, di (meth) acrylate of fluorene and isocyanuric acid, and di (meth) acrylate of an alkylene oxide adduct of these alcohols, And di (meth) acrylates of polyalkylene glycols such as ethylene glycol and propylene glycol. Compounds having three (meth) acryloyl groups include tri (meth) acrylates of pentaerythritol, trimethylolpropane and isocyanuric acid, and tri (meth) acrylates of alkylene oxide adducts of these alcohols. ) Examples of the compound having 4 or more acryloyl groups include pentaerythritol, poly (meth) acrylate of dipentaerythritol, and the like. Also, conventionally known (meth) acryloyl group-containing nomers / oligomers such as urethane acrylates having a urethane bond as the main chain and polyester acrylates having an ester bond as the main chain can be selected and used in a timely manner. .

  In addition, the compound which has the ethylenically unsaturated bond mentioned above may be used individually by 1 type, and may use 2 or more types together, Usually 2.0 mass% or more in composition for holographic recording, 50 mass% % Or less, and more preferably 4.0% by mass or more and 40% by mass or less.

  Next, the photopolymerization initiator will be described in detail.

  The photopolymerization initiator according to the present invention is not particularly limited as long as it can generate radicals by light. Conventionally known benzoin and derivatives thereof, carbonyl compounds such as benzophenone, and azo compounds such as azobisisobutyronitrile. , Sulfur compounds such as dibenzothiazolyl sulfide, peroxides such as benzoyl peroxide, halides such as 2-tribromomethanesulfonyl-pyridine, quaternary ammonium salts or substituted or unsubstituted diphenyliodonium salts, triphenylsulfonium Onium compounds such as salts, bisimidazole compounds such as 2,2-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, metal π complexes such as iron arene complexes and titanocene complexes Select and use photopolymerization initiator as appropriate. Among these, in particular, at least one compound selected from bisimidazole compounds, metal π complexes, and compounds represented by the general formula (1) is more preferable in terms of sensitivity and stability, and metal Among the π complexes, iron arene complexes are particularly preferable.

  Specific examples of such bisimidazole compounds include 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis ( o-chlorophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole, 2,2'-bis (o-chlorophenyl) -4,4', 5,5'-tetrakis (3 , 4,5-trimethoxyphenyl) biimidazole, 2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (p- Bromophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (p-carboxyphenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2 , 2'-bis (p Cyanophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole, 2,2'-bis (2,4-dichlorophenyl) -4,4', 5,5'-tetraphenyl Biimidazole, 2,2'-bis (2,4-dimethoxyphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-fluorophenyl) -4,4' , 5,5'-tetraphenylbiimidazole, 2,2'-bis (m-fluorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (p-fluorophenyl) ) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-hexylphenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2'- Bis (o-hexy Phenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole, 2,2'-bis (3,4-methylenedioxyphenyl-chlorophenyl) -4,4', 5,5 '-Tetraphenylbiimidazole, 2,2'-bis (o-chlorophenyl) -4,4', 5,5'-tetrakis [m- (β-phenoxy-ethoxyphenyl)] biimidazole, 2,2'- Bis (2,6-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-methoxyphenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole Imidazole, 2,2'-bis (p-methoxyphenyl) -4,4'-bis (o-methoxyphenyl) -5,5'-diphenylbiimidazole, 2,2'-bis (o-nitrophenyl)- , 4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (p-phenylsulfonylphenylsulfonylphenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2'- Bis (p-sulfamoylphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (2,4,6-trimethylphenyl) -4,4', 5,5 '-Tetraphenylbiimidazole, 2,2'-bis (4-biphenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2'-bis (1-naphthyl) -4,4 ' , 5,5'-tetraphenylbiimidazole, 2,2'-bis (1-naphthyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole, 2,2'-bis ( 9-Fena Triyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole, 2,2'-diphenyl-4,4', 5,5'-tetrakis (4-biphenyl) biimidazole, 2 , 2'-diphenyl-4,4 ', 5,5'-tetrakis (2,4-xylyl) biimidazole, 2,2'-bis (3-pyridyl) -4,4', 5,5'-tetra Phenylbiimidazole, 2,2'-bis (3-thienyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-tolyl) -4,4', 5 5'-tetraphenylbiimidazole, 2,2'-bis (p-tolyl) -4,4'-bis (o-tolyl) -5,5'-tetraphenylbiimidazole, 2,2'-bis (2,4-Xylyl) -4,4 ', 5,5'-tetraf Phenylbiimidazole, 2,2 ', 4,4', 5,5'-hexakis (p-benzylthiophenyl) biimidazole, 2,2 ', 4,4', 5,5'-hexa (1-naphthyl) ) Biimidazole, 2,2 ', 4,4', 5,5'-hexaphenylbiimidazole, 2,2'-bis (2-nitro-5-methoxyphenyl) -4,4 ', 5,5' -Tetraphenylbiimidazole, 2,2'-bis (o-nitrophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole, 2,2'-bis (2-chloro- 5-sulfophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole and the like, and “Photoinitiators or Free-Radical-Initiated Photoi”. aging Systems ", Chem. Rev. , 93, p. 435-448 (1993), S.A. P. P. Of Pappas, “Radiation Curing: Science and Technology, Plenum Press New York, (1992)”. Examples thereof include compounds described in 407-412 and the like.

  Specific examples of the iron arene complex include (η6-m-xylene) (η5-cyclopentadienyl) iron (1+) tetrafluoroborate, (η6-o-xylene) (η5-cyclopentadienyl). ) Iron (1+) triflate, (η6-o-xylene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-p-xylenes) (η5-cyclopentadienyl) iron ( 1+) triflate, (η6-acetophenone) (η5-methylcyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-xylenes (mixed isomers)) (η5-cyclopentadienyl) iron (1+) ) Hexafluoroantimonate, (η6-xylenes (mixed isomers)) (η5-cyclopentadienyl) iron (1+) hexafluorophosphine (Η6-cumene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-cumene) (η5-cyclopentadienyl) iron (1+) hexafluorophosphate, (η6-cumene) (Η5-cyclopentadienyl) iron (1+) hexafluoroarsenate, (η6-chrysene) (η5-cyclopentadienyl) iron (1+) pentafluorohydroxyantimonate, (η6-toluene) (η5-cyclopenta (Dienyl) iron (1+) hexafluoroarsenate, (η6-toluene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-naphthalene) (η5-cyclopentadienyl) iron (1+ ) Tetrafluoroborate, (η6-pyrene) (η5-cyclopentadienyl) iron (1+) Frete, (η6-fluorene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-hexamethylbenzene) (η5-cyclopentadienyl) iron (1+) pentafluorohydroxyantimonate, ( η6-perylene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-benzene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-mesitylene) (η5 -Cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-mesitylene) (η5-cyclopentadienyl) iron (1+) hexafluorophosphate, (η6-mesitylene) (η5-cyclopentadienyl) iron (1+) pentafluorohydroxyantimonate and (η6-c Men) (η5-cyclopentadienyl) iron (1+) butyltriphenylborate and the like.

  Furthermore, it does not absorb the wavelength of the light source used for holographic exposure of the photopolymerization initiator with respect to the wavelength of the exposure light source used in the holographic exposure described later, or even if it has it. When the amount is small, it is more preferable to use a sensitizing dye for sensitizing the spectral wavelength of the photopolymerization initiator in combination.

  Examples of the sensitizing dye for sensitizing the spectral wavelength of the photopolymerization initiator used here include various dyes used in the art, such as carbonyl derivatives such as Michler's ketone, and coumarin derivatives. , Methine derivatives, polymethine derivatives, triarylmethane derivatives, indoline derivatives, azine derivatives, thiazine derivatives, xanthene derivatives, thioxanthene derivatives, oxazine derivatives, acridine derivatives, cyanine derivatives, carbocyanine derivatives, merocyanine derivatives, hemicyanine derivatives, rhodocyanine derivatives , Azamethine derivatives, styryl derivatives, pyrylium derivatives, thiopyrylium derivatives, porphyrazine derivatives, porphyrin derivatives, phthalocyanine derivatives and pyromethene derivatives, and 2,5-thiofezyl (5-t-butyl) May be used in combination of two or more depending 1,3-benzoxazole) various dyes such as optical brightening agents, such as single or required.

  Specific examples of such photopolymerization initiators or sensitizing dyes include, for example, US Pat. Nos. 5,027,436, 5,096,790, 5,147,758, and 5, 204,467, 5,256,520, 6,011,180, European Patent Nos. 255,486, 256,981, 277,915, 318,893, 401, No. 165, No. 565,488, No. 1,349,006, JP-A-2-236553, No. 5-46061, No. 5-216227, No. 5-247110, No. 5-257279 6-175554, 6-175562, 6-175563, 6-175656, 6-186899, 6-195015, 6-202540, 6-202541 6-202543, 6-202544, 6-202548, 6-324615, 6-329654, 7-13473, 7-28379, 7-84502, 7-84503, 7-181876, 9-106069, 9-309907, JP-A-2002-60429, 2002-62786, 2002-244535, 2002-296765 Can be selected and used in a timely manner.

  Furthermore, the photopolymerization initiator represented by the general formula (1) can also be suitably used in the present invention. In this photopolymerization initiator, the initiation is performed with respect to the exposure light source wavelength for holographic exposure with the photoradical initiator. Compared with the initiator system in combination with a sensitizing dye for spectrally sensitizing the agent, the radicals are generated efficiently because the boron anion moiety that generates radicals is in the vicinity of the cationic dye that is the sensitizing dye. At the same time, the wavelength of the light source used for holographic exposure can be easily adjusted by changing the structure of the cationic dye.

In the formula, Dye ⁺ represents a cationic dye, R _{1 to} R ₄ each represents a substituted or unsubstituted alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, heterocyclic group or cyano group, and R ₁ Two or more of R ₄ may be bonded to each other to form a ring.

In the above general formula (1), in order to efficiently generate a radical from a boron anion, at least one of the substituents represented by R _{1 to} R ₄ in the boron anion part is a substituted or unsubstituted alkyl group, It is preferably an aralkyl group, an alkenyl group or an alkynyl group, and the other substituent is preferably a substituted or unsubstituted aryl group or heterocyclic group.

Furthermore, as the cationic dye represented by Dye ⁺ in the compound represented by the general formula (1), a cationic dye conventionally used in various fields can be appropriately selected and used. Among them, methine dye, polymethine dye, triarylmethane dye, indoline dye, azine dye, thiazine dye, xanthene dye, oxazine dye, acridine dye, cyanine dye, carbocyanine dye, hemicyanine dye, rhodocyanine dye, azamethine dye, styryl dye , A pyrylium dye, a thiopyrylium dye, and a coordination metal complex represented by the following general formula (2) are preferable.

Formula (2) M ^{a +} (L) _b
In the formula, M represents a metal atom, a represents an integer of 1 to 4, L represents a ligand, and b represents an integer of 1 to 6.

  Furthermore, from the viewpoint of the stability of the coordination metal complex, the ligand represented by L in the general formula (2) is a dye capable of chelating at two or more positions with respect to the metal ion. This is preferable because the spectral maximum wavelength can be easily adjusted when the exposure light source wavelength for holographic exposure is 500 nm or more.

  Examples of the dye that can chelate at two or more positions include the following dyes.

In the formula, X ₁ is an aromatic group in which at least one carbon adjacent to the azo bond is substituted with a nitrogen, oxygen, sulfur, selenium or tellurium atom, and at least one ring is composed of 5 to 7 atoms. X ₂ represents an atomic group necessary to complete a carbocyclic or heterocyclic ring of a group, and at least one ring represents an atomic group necessary to complete a 5-7 carbocyclic or heterocyclic ring, The carbocycle or heterocycle of may be substituted. G represents a chelating group, W represents —COR ₇ or —CSR ₇ , Y represents —O—, —S—, —N═, —NH— or —NR ₈ —, Z represents O or S M and n represent an integer of 1 to 5. R ₁ and R ₂ are hydrogen atom, halogen atom, cyano group, alkyl group, alkenyl group, alkoxy group, alkylsulfonamide group, arylsulfonamide group, anilino group, acylamino group, alkylureido group, arylureido group, alkoxy Represents a carbonyl group, an alkoxycarbonylamino group, a carbamoyl group, a sulfamoyl group, a sulfo group, a carboxy group, an aryl group or a heterocyclic group, and R ₇ represents a hydrogen atom, an alkyl group, an alkenyl group, an alkoxy group, an alkylsulfonamide group, an aryl sulfonamido group, an anilino group, an acylamino group, an alkylureido group, an arylureido group, a carbamoyl group, a sulfamoyl group, an aryl group or a heterocyclic group, R ₈ represents an alkyl group, an alkenyl group, an aryl group or a heterocyclic group .

The metal ions represented by ^{Ma +} in the general formula (2) include silver (I), aluminum (III), gold (III), cerium (III, IV), cobalt (II, III). , Chromium (III), copper (I, II), europium (III), iron (II, III), gallium (III), germanium (IV), indium (III), lanthanum (III), manganese (II), Nickel (II), Palladium (II), Platinum (II, IV), Rhodium (II, III), Ruthenium (II, III, IV), Scandium (III), Silicon (IV), Samarium (III), Titanium ( IV), uranium (IV), zinc (II), zirconium (IV) and the like. Among these, in the case of a bidentate dye, a metal ion that can coordinate in a tetradentate or hexadentate form is preferable. In the case of a tridentate dye, a metal ion capable of coordinating in hexadentate is preferable. Particularly preferred metal ions include zinc (II), nickel (II), cobalt (II, III), copper (II), rhodium (II, III), ruthenium (II, III), palladium (II), platinum (II IV).

  The above-mentioned photopolymerization initiator cannot be generally determined by the molecular weight of the photopolymerization initiator or the proportion of the ethylenically unsaturated bond in the compound having an ethylenically unsaturated bond. It is usually preferable to use in the range of 0.01 to 25 parts by mass with respect to the compound to be contained.

  Furthermore, in the present invention, when producing a holographic recording medium in addition to the above essential components, polymerization is performed before holographic exposure of a catalyst for the purpose of promoting the reaction of the binder-forming compound or a compound having an ethylenically unsaturated bond. A polymerization inhibitor may be added for the purpose of preventing the formation of a polymer, and a plasticizer or a heat-meltable compound may be added for the purpose of controlling the diffusion polymerization of a compound having an ethylenically unsaturated bond. Known compounds that have been known can be selected and used as needed.

  Next, the holographic recording medium of the present invention will be described in detail.

In the holographic recording medium of the present invention, a holographic recording layer is sandwiched between a first substrate and a second substrate, and the holographic recording layer has a binder-forming compound, a compound having an ethylenically unsaturated bond, And a layer containing a photopolymerization initiator capable of initiating a polymerization reaction of the compound having an ethylenically unsaturated bond as an essential component, and the proportion of isocyanate groups as the binder-forming compound is 30% by mass in the compound It contains at least a compound having three or more isocyanate groups in the molecule that is 65% by mass or less , and the proportion of the isocyanate group is 30% by mass or more and 65% by mass or less in the molecule. The compound having an isocyanate group has an isocyanate group contained as a binder-forming compound. It is characterized in that the recording layer has Ru der 100 wt% to 5 wt% or less with respect to the entire compound.

  The proportion of the binder-forming compound, the compound having an ethylenically unsaturated bond, the photopolymerization initiator capable of initiating the polymerization reaction of the compound having the ethylenically unsaturated bond, and the isocyanate group is 30 in the compound. The compound having 3 or more isocyanate groups in the molecule of not less than 65% by mass and not more than 65% by mass is synonymous with that described in detail for the holographic recording composition.

  Next, the 1st base material and the 2nd base material which comprise a recording medium are demonstrated. The first base material here refers to a base material on the side on which information light and reference light are incident or a reproduction light for reproduction when performing holographic exposure for recording information on a recording medium. It is a substrate on the irradiation side, and the second substrate refers to a substrate opposite to the first substrate with the holographic recording layer interposed therebetween.

  As the first base material and the second base material used in the recording medium of the present invention, those which are transparent and do not cause expansion and contraction or bending at the use environment temperature, and further inert to the recording composition described above. Any material can be used without particular limitation. Examples of such a substrate include quartz glass, soda glass, potash glass, lead crystal glass, borosilicate glass, aluminosilicate glass, titanium crystal glass, and crystallized glass. List various resins such as glass, polycarbonate, polyacetal, polyarylate, polyetheretherketone, polysulfone and polyethersulfone, polyimide such as polyimide-amide and polyetherimide, polyamide, and polyolefin such as cyclic olefin ring-opening polymer Can do.

  Among the above-mentioned base materials, information light and reference light are incident from the viewpoints of thickness variation with respect to environmental temperature and humidity during holographic exposure, gas permeability, and light transmittance of the light source wavelength used during holographic exposure. It is more preferable to use glass as the material of the first base material on the side to be used. The second substrate is preferably made of glass like the first substrate. However, if the device is provided with a focus correction mechanism when reading holographically recorded information with a CCD, the stretch rate and thickness Instead of a glass-like base material with suppressed fluctuations, a base material made of resin may be used.

Further, the transmittance of the incident light of the first base material on the side on which the information light and the reference light are incident is preferably 70% or more, and more than 80% has little loss of light reaching the holographic recording layer. Is more preferable. In order to increase the transmittance as much as possible, it is preferable that the first base material surface opposite to the surface on which the holographic recording layer is laminated is subjected to an antireflection treatment. The refractive index is not particularly limited as long as the refractive index is lower than that of the first base material. For example, inorganic metal fluorides such as AlF ₃ , MgF ₂ , AlF ₃ .MgF ₂ , CaF ₂ , vinylidene fluoride, Teflon (R), etc. Organic fluorides such as homopolymers, copolymers, graft polymers, block polymers, modified polymers modified with functional groups containing fluorine atoms, etc. as described above in detail as substrates Is preferable because the refractive index is low.

  In addition, as a method of providing a layer made of a fluorine-based compound on a substrate, it cannot be determined in general depending on the type of the support or the fluorine-based compound, but a sol-gel method, a vacuum evaporation method, a sputtering method, a CVD method, etc. A known method such as a coating method or a coating method, or a method described in JP-A-7-27902, JP-A-2001-123264, JP-A-2001-264509, or the like can be appropriately selected and used.

  Such an antireflection layer cannot be generally defined by the surface treatment or material of the substrate, but is usually in the range of 0.001 to 20 μm, preferably in the range of 0.005 to 10 μm.

  Moreover, a second base material holographic recording layer is laminated on a recording medium used in a holographic recording / reproducing apparatus such as JP 2002-123949 A and WO 99/57719 pamphlet. It is preferable that a reflective layer is provided on the surface to be reflected or the opposite surface, and when the reflective layer is provided in this way, the reflectance is preferably 70% or more with respect to the wavelength of light to be reflected, and further 80 % Or more is more preferable.

  Such a reflective layer is not particularly limited in material as long as a desired reflectance is obtained, but can be laminated by providing a thin film of metal or the like on the substrate surface. For example, in order to form such a reflective layer, it can be laminated as a metal thin film, a metal single crystal or a polycrystal by a known method such as a vacuum deposition method, an ion plating method, or a sputtering method. The metals used for laminating aluminum, zinc, antimony, indium, selenium, tin, tantalum, chromium, lead, gold, silver, platinum, nickel, niobium, germanium, silicon, molybdenum, manganese, tungsten, palladium These metals can be formed singly or in combination of two or more. The thickness of the metal thin film layer may be any thickness as long as the desired reflectance can be obtained, but is usually in the range of 1 to 3000 nm, and preferably in the range of 5 to 2000 nm.

  On the other hand, in a holographic recording medium, a recording medium having a high storage capacity can be created by making the holographic recording layer as thick as possible. However, the use environment of the recording medium, reading error of recorded information, etc. In consideration of this, in the present invention, when the thickness of the first substrate is d1, the thickness of the second substrate is d2, and the thickness of the holographic recording layer is Dh, 0.15 ≦ Dh / (d1 + d2 ) ≦ 2.0 is preferably satisfied.

  Here, if 0.15> Dh / (d1 + d2), the thickness of the holographic recording layer cannot be increased, or even if the thickness of the recording layer is increased, the thickness of the base material is increased, and the entire recording medium is increased. turn into. This is not preferable because the mass of the recording medium alone is heavy and a load on the drive system of the apparatus may occur. When Dh / (d1 + d2)> 2.0, it is possible to reduce the thickness of the recording medium while ensuring the thickness of the recording layer. Thickness increases, surface accuracy of recording media, unevenness of recording layer at operating temperature, fluctuation of recording layer when unintentional stress is applied, and first and second substrates Is not preferable because it may shift.

  Furthermore, in terms of energy loss during holographic exposure, the relationship between the thickness d1 of the first base material and the thickness d2 of the second base material is preferably d1 ≦ d2, and the flatness of the recording medium is ensured. Therefore, it is more preferable that the thickness ratio of d1 and d2 is in the range of 0.20 ≦ d1 / d2 ≦ 1.00.

  Further, the thickness Dh of the holographic recording layer is not generally determined by the diffraction efficiency, dynamic range, spatial resolution, or the like of the recording layer, but is usually preferably 200 μm or more and 2.0 mm or less, and is less than 200 μm. When a recording medium having a storage capacity cannot be obtained and is thicker than 2.0 mm, it is not preferable because unevenness in the thickness of the recording layer at the surface accuracy of the recording medium or the use environment temperature may occur.

  On the other hand, the shape of the recording medium is not particularly limited as long as it is suitable for the holographic recording / reproducing apparatus used for the recording medium. For example, US Pat. No. 5,719,691, JP, If it is used for the apparatus described in 2002-123949 etc., the disk-shaped thing is preferable, and if it uses the apparatus described in the international publication 99/57719 pamphlet etc., a card-like thing is preferable. .

  As described above in detail, as a method for producing a recording medium, a holographic recording composition is prepared by mixing the holographic recording composition by heating at room temperature or as necessary under a safelight, After degassing in order to suppress polymerization inhibition during holographic exposure, a holographic recording composition heated to room temperature or as necessary is attached to the first substrate, and then the second substrate is pre-determined. After pasting so that bubbles do not enter so as to have the thickness of the recording layer, the recording medium can be manufactured by finally sealing the end. In addition, the first base material and the second base material are fixed to a mold under a safelight so as to have a predetermined gap, and bubbles do not enter the holographic recording composition heated at room temperature or as necessary. Thus, it is possible to create a recording medium by filling between the first base material and the second base material by injection molding or sucking under reduced pressure so that bubbles do not enter, and finally sealing the end portion. . The term “under safe light” as used herein refers to an operation in a state in which the wavelength of light at which the photopolymerization initiator becomes active is cut.

  Further, when creating a recording medium by bonding, the holographic recording composition may be applied on the second substrate instead of the above-described first substrate, You may attach to both of two base materials. Furthermore, when sealing the edge part of a 1st base material, a holographic recording layer, and a 2nd base material, the liquid sealing material represented by the moisture hardening type adhesive which can be sealed May be cross-linked and sealed, or the holographic recording layer may be sealed in advance using an end sealing material on a ring for ensuring a predetermined film thickness.

  Next, a method for recording information on the holographic recording medium will be described in detail.

In the first aspect of the holographic recording method of the present invention, a holographic recording layer is sandwiched between a first substrate and a second substrate, and the binder forming compound, ethylenic compound is used as the holographic recording layer. It contains at least a photopolymerization initiator capable of initiating a polymerization reaction of a compound having an unsaturated bond and the compound having an ethylenically unsaturated bond, and the proportion of isocyanate groups in the compound is 30 in the compound. It contains at least a compound having 3 or more isocyanate groups in the molecule of not less than 65% by mass and a compound having 2 or more hydroxyl groups in the molecule, and the proportion of the isocyanate group is 30% in the compound. % Or more and 65% by mass or less of a compound having 3 or more isocyanate groups in the molecule forms a binder. In the method 100 wt% or less der Ru recording layer more than 5% by weight, based on the total compound having an isocyanate group contained is the holographic recording on a holographic recording medium which are stacked as a compound, prior to holographic exposure After the binder-forming compounds react with each other to form a binder, holographic exposure based on the information to be recorded is performed, the photopolymerization initiator is activated, and the compound having an ethylenically unsaturated bond is holoed by this active species. Information is recorded on a holographic recording medium by diffusion polymerization in the graphic recording layer.

  In general, when a thick film layer is added, a recording composition is prepared without a solvent for dilution. For a solid or high viscosity composition, a uniform film thickness is obtained or air bubbles are involved during the preparation of the composition. Removal becomes difficult. For this reason, fluidity is required at normal temperature or when the recording composition is prepared. When this recording composition is liquid at room temperature and has a low viscosity, it is difficult to ensure flatness as a recording medium, or has an ethylenically unsaturated bond after information is recorded by holographic exposure. Since the polymer formed of the compound may be displaced in the recording layer, it is not preferable.

  Therefore, the holographic recording medium containing the above-mentioned essential components is made into a binder by crosslinking a binder-forming compound before holographic exposure, and an ethylenically unsaturated bond is formed at the time of ensuring flatness and holographic exposure. The movement of the polymer formed by the diffusion polymerization of the compound having it in the holographic recording layer can be prevented.

  Next, after the binder is formed, holographic exposure based on the information to be recorded is performed, the photopolymerization initiator is activated, and the compound having an ethylenically unsaturated bond in the molecule is diffused by this active species. By doing so, information can be recorded on the holographic recording medium.

  The crosslinking reaction for forming the binder in this recording method may be performed by crosslinking all combinations of functional groups capable of reacting the isocyanate group of the compound having an isocyanate group and the hydroxyl group of the compound having a hydroxyl group, You may bridge | crosslink only a part in the range which does not cause trouble practically. Furthermore, after recording information on the holographic recording medium, the isocyanate group and hydroxyl group of the remaining isocyanate group are generated by light and heat applied as necessary for the purpose of fixing the recorded holographic information. It is preferable to polymerize with a photopolymerization initiator that can crosslink a hydroxyl group of a compound having a compound and a compound having an ethylenically unsaturated bond in the molecule. In this case, it is preferable that the light used for the exposure is collectively exposed to the entire recording medium. When heating is performed, it may be before the batch exposure, at the same time as the batch exposure or after the batch exposure, or a plurality of heat treatments. You may combine.

In the second aspect of the holographic recording method of the present invention, a holographic recording layer is sandwiched between a first substrate and a second substrate, and the binder forming compound, ethylenic compound is used as the holographic recording layer. It contains at least a photopolymerization initiator capable of initiating a polymerization reaction of a compound having an unsaturated bond and the compound having an ethylenically unsaturated bond, and the proportion of isocyanate groups as the binder-forming compound is 30% by mass. A compound having 3 or more isocyanate groups in a molecule that is not less than 65% by mass and not more than 65% by mass , and the proportion of the isocyanate group is 30 to 65% by mass in the compound. Compound having an isocyanate group is contained as a binder-forming compound. Or less to 100 mass% to 5 mass% for a method of further holographic recording on a holographic recording medium having a recording layer are laminated which contains at least a compound having two or more hydroxyl groups in a molecule, recorded information desired Holographic exposure is performed based on the photopolymerization initiator, the photopolymerization initiator is activated, and a compound having an ethylenically unsaturated bond is diffusion-polymerized by the active species to record information on the holographic recording medium. after the information recording to the media has been completed, and further characterized in that to stabilize the recorded information by performing heat and light irradiation to the entire holographic recording medium.

  Unlike the first embodiment described above, this embodiment is a composition that flows in a heated state but does not flow at room temperature when a recording composition is prepared, or gels at room temperature unless shear stress is applied. Alternatively, the recording method is effective for a holographic recording medium in which a recording layer is formed from a thixotropic recording composition.

  In such a recording medium, the level of the recording medium should be at a level that does not cause any practical problem with respect to ensuring the flatness of the recording medium and preventing migration of a polymer formed by diffusion polymerization of a compound having an ethylenically unsaturated bond. However, for the purpose of further improving the storage stability of recorded information, after recording information on the holographic recording medium, the hydroxyl group of the compound having the isocyanate group and the hydroxyl group of the compound having the remaining isocyanate group is retained by light and heat. And a photopolymerization initiator that can crosslink a compound having an ethylenically unsaturated bond, and is preferably polymerized. In this case, as in the first aspect described above, it is preferable that the light used for exposure is exposed all over the recording medium, and when the recording medium is heated, either before the batch exposure, simultaneously with the batch exposure or after the batch exposure. It may be present or some heat treatments may be combined.

  In addition, as an apparatus for recording / reproducing holographic recording media used in the recording methods of the first and second aspects of the present invention, any apparatus capable of recording / reproducing with respect to the recording medium of the present invention can be used. There are no limitations, and examples of such recording / reproducing apparatuses include, for example, US Pat. Nos. 5,719,691, 5,838,467, 6,163,391, and 6,414,296. No. 2002-136143, JP-A-9-305978, JP-A-10-124872, JP-A-11-219540, JP-A-2000-98862, JP-A-2000-29883, 2001-23169, 2002-83431, 2002-123949, 2002-123948, 2003-43904 WO 99/57719, the 02/05270 Patent, may be mentioned those described in the pamphlets of Nos. 02/75727.

  As a light source as a laser used in the recording / reproducing apparatus described above, a laser light source capable of holographic recording by activating a photopolymerization initiator in a recording medium and reading a recorded hologram can be used. The light source can be used without limitation, such as blue-violet semiconductor laser, argon laser, He-Cd laser, double-frequency YAG laser, He-Ne laser, Kr laser, near-infrared semiconductor laser, etc. Can be mentioned.

  In addition, a holographic recording medium before recording and a holographic recording medium with a small amount of recorded information that may be additionally recorded are (λ + 100) nm or less when the wavelength of a light source usually used for holographic recording is λ nm. Preferably, it is stored and placed in a case or cassette that can at least block light with respect to (λ + 200) nm or less, and is taken out from the case or cassette only when the recording medium is exposed and recorded with a laser beam. Information is recorded by irradiating light.

  Furthermore, the recording medium on which information is recorded by the holographic recording method of the present invention can be taken out from the above-described case or cassette that can be shielded from light and used as a holographic information medium that can be handled in a bright room like a CD or DVD. Can be used. In this holographic information medium, a holographic information recording layer is sandwiched between a first base material and a second base material, and the proportion of isocyanate groups in the holographic information recording layer is 30% by mass or more in the compound. A region mainly composed of a urethane compound formed by the reaction of a compound having 3 or more isocyanate groups in the molecule and a compound having 2 or more hydroxyl groups in the molecule, and having an ethylenic concentration of 65% by mass or less; And a region mainly composed of a radical polymer formed by radical polymerization of a compound having a saturated bond. This holographic information medium is an information recording layer on which information is recorded under normal use conditions. Since there is almost no coloring, there is almost no reading failure in the reproducing apparatus over time.

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

  The binder-forming compounds (A-1 to 2, B-1 to 6, C-1 to 5) and compounds having an ethylenically unsaturated bond (D-1) used in preparing the holographic recording composition To 7), photopolymerization initiator (E-1 to 5), and sensitizing dye (F-1 to 7) are shown below.

<Binder forming compound>
A: Compound having 3 or more isocyanate groups in the molecule in which the proportion of isocyanate groups is 30% by mass or more and 65% by mass or less in the compound (A-1) 1,8-diisocyanate-4-isocyanatomethyl-octane ( NCO content: 50.2 mass%, molecular weight: 251.3)
(A-2) 2-isocyanatoethyl-2,6-diisocyanate caproate (NCO content: 49.8 mass%, molecular weight: 253.2)
B: Compound having two or more isocyanate groups in the molecule other than A (B-1) Hexamethylene diisocyanate 3 mol adduct (NCO content: 21.0% by mass: Nippon Polyurethane Industry Co., Ltd., Coronate HX )
(B-2) Hexamethylene diisocyanate (NCO content: 50.0% by mass)
(B-3) Polyisocyanate of hexamethylene disiciocyanate (NCO content: 19.7% by mass: manufactured by Asahi Kasei Corporation, Duranate D-101)
(B-4) Hexamethylene disiciocyanate polyisocyanate (NCO content: 12.1% by mass: manufactured by Asahi Kasei Corporation, Duranate TSE-100)
(B-5) Methylsilane triisocyanate (NCO content: 74.5% by mass)
(B-6) Diphenylmethane-4,4'-diisocyanate (NCO content: 33.6% by mass)
C: Compound having two or more hydroxyl groups in the molecule (C-1) Polypropylene oxide adduct of glycerin (average molecular weight 330: Uniol TG-330, manufactured by NOF Corporation)
(C-2) Polypropylene oxide adduct of glycerin (average molecular weight 1000: manufactured by NOF Corporation, Uniol TG-1000)
(C-3) Polypropylene glycol (average molecular weight 1000: manufactured by NOF Corporation, Uniol D-1000)
(C-4) Triethylene glycol (molecular weight 150.2)
(C-5) 1,12-dodecanediol (molecular weight 202.3)
<Compound having an ethylenically unsaturated bond>
(D-1) Hydroxyethylated o-phenylphenol acrylate (refractive index = 1.576: manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester А-L4)
(D-2) Paracumylphenoxyethylene glycol acrylate (refractive index = 1.553: manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester А-CMP-1E)
(D-3) 9,9-bis (3-phenyl-4-acryloylpolyoxyethoxy) fluorene (refractive index = 1.597: manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester А-BPFL-4E)
(D-4) Tribromophenyl acrylate (refractive index * 1 = 1.567: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., New Frontier BR-30)
(D-5) EO-modified tribromophenyl acrylate (refractive index * 1 = 1.564: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., New Frontier BR-31)
(D-6) EO-modified tetrabromobisphenol A dimethacrylate (refractive index * 1 = 1.564: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., New Frontier BR-42M)
(D-7) Phenoxyethyl acrylate (refractive index = 1.519)
The refractive index * 1 was measured at 25 ° C. as a 50% styrene solution.

<Photopolymerization initiator, sensitizing dye>
Photopolymerization initiators (E-1 to 5) and sensitizing dyes (F-1 to 7) are shown below.

<< Preparation of composition for holographic recording >>
A compound having an ethylenically unsaturated bond was dissolved in the isocyanate compound shown in Table 1, and then a photopolymerization initiator was dissolved in this solution. Separately, a solution in which a sensitizing dye and a urethane curing catalyst (manufactured by Nitto Kasei Co., Ltd., Neostan U-100) are dissolved in a compound having two or more hydroxyl groups in the molecule is used as a solution in which this photopolymerization initiator is dissolved. After the composition prepared at the end was deaerated with nitrogen, the gas components contained therein were removed by vacuum deaeration to prepare compositions 1 to 35 for holographic recording. The composition 35 was prepared by dissolving a sensitizing dye and a urethane curing catalyst in a compound having two or more hydroxyl groups in the molecule, and then adding 0.150 g of 2-mercaptobenzthiazole.

<Production of holographic recording media>
(Production Method 1)
As the first base material and the second base material, one side of glass having a thickness of 0.5 mm (d1, d2) is reflected so that the reflectance by incident light perpendicular to the wavelength of 532 nm is 0.1%. Prevented treatment. The composition for holographic recording described in Table 1 using a polyethylene terephthalate sheet as a spacer on the surface of the first base material that has not been subjected to antireflection treatment so as to have the thickness of the recording layer described in Table 2. Is attached to the first substrate, and then the non-reflective surface of the second substrate is bonded so as not to entrain the air layer on the holographic recording composition, and through a spacer. The 1st base material and the 2nd base material were bonded. Finally, the end was sealed with a moisture-curing adhesive, and heat-treated under the heat treatment conditions described in Table 2 to produce a holographic recording medium.

(Production method 2)
An antireflection treatment is performed on one surface of a glass having a thickness of 0.5 mm so that the reflectance by incident light perpendicular to the wavelength of 532 nm is 0.1%, whereby the first substrate has a thickness of 0.5 mm. A second substrate was prepared by performing aluminum deposition on one side of the glass so that the reflectance by incident light perpendicular to the wavelength of 532 nm was 90%. Next, on the surface of the first base material that has not been subjected to antireflection treatment, a polyethylene terephthalate sheet is used as a spacer so as to have the thickness of the recording layer described in Table 3, and the holographic recording described in Table 1 The composition for application is applied to the first substrate, and then the aluminum-deposited surface of the second substrate is bonded to the holographic recording composition so as not to entrain the air layer, and the first substrate is passed through the spacer. One substrate and a second substrate were bonded together. Finally, the end was sealed with a moisture-curing adhesive, and heat-treated under the heat treatment conditions described in Table 3 to produce a holographic recording medium.

<Recording and evaluation on holographic recording media>
(Recording on holographic recording media and evaluation 1)
A series of multiple holograms is written on the holographic recording medium manufactured as described above according to the procedure described in US Pat. No. 5,719,691, and sensitivity (recording energy) and shrinkage resistance are determined according to the following methods. And, the contrast of the refractive index was measured and evaluated, and the obtained results are shown in Table 4.

(Measurement of sensitivity)
A digital pattern was displayed on a holographic recording medium under a safe light with a holographic production apparatus equipped with an Nd: YAG laser (532 nm), and this digital pattern was formed with an energy of 0.1 to 30 mJ / cm ² . Holograms were obtained by holographic exposure. Next, using a Nd: YAG laser (532 nm) as a reference light, the generated reproduction light was read by a CCD, and the minimum exposure amount at which a good digital pattern could be reproduced was measured as sensitivity (S1).

(Evaluation of shrinkage resistance)
The shrinkage resistance is displayed as a shrinkage rate measured by the following method.

  FIG. 1 is a schematic diagram showing the principle of a measuring apparatus for measuring the shrinkage rate. That is, the emission point of the white illumination light source that illuminates the hologram 3 is 01, and the observer's viewpoint is 02. In the measuring apparatus, the white illumination light source 4 is installed at the light emission point 01 and the spectroscope 5 is installed at the viewpoint 02. The spectroscope 5 is connected to a personal computer 6, and a moving pinhole plate 7 is provided on the upper surface of the hologram 3 for measuring the spectral wavelength luminance distribution. Has been. The moving pinhole plate 7 is attached to an XY stage (not shown) and can move to an arbitrary position.

  That is, when the moving pinhole plate 7 is at the point P (I, J), the angle from the center of the pinhole 8 to the white illumination light source 4 is θc, and the angle from the spectroscope 5 is θi. The area of the point P (I, J) of the hologram 3 is illuminated with the illumination light 9 from the angle θc, and the reproduction light 11 is emitted in the direction θi. The reproduction light 11 is split by the spectroscope 5 and the wavelength at which the luminance reaches a peak is the reproduction wavelength λc at P (I, J). Using this relationship, θc, θi, and λc at each position of the hologram 3 are measured while moving the moving pinhole plate 7.

  Further, if the shrinkage ratio of the hologram at the point P (I, J) is M (I, J), the shrinkage ratio M (I, J) of the hologram is the average refractive index of the optical image recording material before recording nr. If the average refractive index of the hologram after development processing is nc, it can be expressed by the following equation.

M (I, J) = − nc / nr · λr / λc · (cos θc−cos θi) / (cos θo−cos θr)
In the above equation, θo is the incident angle to the holographic recording medium, λr is the wavelength of the laser beam, and θr is the incident angle of the reference light to the holographic recording medium.

(Evaluation of refractive index contrast)
The refractive index contrast was determined from the diffraction efficiency measured according to the following method. For the measurement of diffraction efficiency, an ART25C spectrophotometer manufactured by JASCO Corporation was used, and a photomultimeter having a slit with a width of 3 mm was placed on a circumference with a radius of 20 cm centered on the sample. Monochromatic light having a width of 0.3 mm was incident on the sample at an angle of 45 degrees, and diffracted light from the sample was detected. The ratio of the largest value other than the specularly reflected light and the value when directly receiving incident light without placing a sample was taken as the diffraction efficiency, and the refractive index contrast (Δn) was determined from the diffraction efficiency of the obtained hologram.

  From the above table, it can be seen that the recording medium of the present invention has a high sensitivity, a low shrinkage ratio, and a high contrast with respect to the comparative example, and shows good results.

(Recording on holographic recording media and evaluation 2)
The holographic recording medium manufactured as described above is written with a series of multiple holograms according to the procedure described in US Pat. No. 5,719,691, and sensitivity (recording energy) and evaluation are performed according to the following methods. 1, the shrinkage resistance and the refractive index contrast were measured and evaluated, and the results obtained are shown in Table 5.

(Measurement of sensitivity)
A digital pattern was displayed on a holographic recording medium under a safe light with a holographic production apparatus equipped with an Nd: YAG laser (532 nm), and this digital pattern was formed with an energy of 0.1 to 30 mJ / cm ² . Holograms were obtained by holographic exposure. Next, the holographic recording medium was treated for 5 minutes under a 70,000 lux sunshine fade meter and then heated at 100 ° C. for 5 minutes. Using this processed recording medium under a safe light, an Nd: YAG laser (532 nm) is used as a reference light, the generated reproduction light is read by a CCD, and the minimum exposure amount at which a good digital pattern can be reproduced is sensitivity (S1). As measured.

  From the above table, it can be seen that evaluation 1 is reproduced, and the recording medium of the present invention has high sensitivity, low shrinkage ratio, and high contrast with respect to the comparative example, and shows good results.

(Recording on holographic recording media and evaluation 3)
The holographic recording medium produced as described above is written according to the procedure described in JP-A-2002-123949, a series of multiple holograms is written, and the sensitivity (recording energy) is measured and evaluated according to the following method. The results obtained are shown in Table 6.

(Measurement of sensitivity)
A digital pattern was displayed on a holographic recording medium under a safe light with a holographic production apparatus equipped with an Nd: YAG laser (532 nm), and this digital pattern was formed with an energy of 0.1 to 30 mJ / cm ² . Holograms were obtained by holographic exposure. Next, the holographic recording medium was treated for 5 minutes under a 70,000 lux sunshine fade meter and then heated at 100 ° C. for 5 minutes. Using this processed recording medium under a safe light, an Nd: YAG laser (532 nm) is used as a reference light, the generated reproduction light is read by a CCD, and the minimum exposure amount at which a good digital pattern can be reproduced is sensitivity (S1). As measured.

  From the above table, evaluations 1 and 2 are reproduced, and it can be seen that the recording medium of the present invention is highly sensitive and shows good results compared to the comparative example.

(Evaluation of holographic information media)
The holographic information media created in Table 7 and Table 8 with the recorded information fixed are stored under the following conditions, and the digital pattern is reproduced and evaluated by a method suitable for each information medium before and after storage. The difference in the minimum exposure amount that could be reproduced before and after storage was evaluated by the following method, and the results obtained are shown in Table 7. In addition, the degree of coloring of the holographic information media was evaluated by the following method, and the obtained results are shown in Table 8.

(Heat resistant storage stability)
The holographic information media was stored at 80 ° C. for 2 weeks, and the minimum exposure sensitivity difference (ΔSh) before and after storage was determined.

Minimum exposure sensitivity difference (ΔSh) = Minimum exposure sensitivity after storage (S2h) −Minimum exposure sensitivity before storage (S1h)
(Light-resistant storage stability)
The sample was stored for 1 week under a 70,000 lux sunshine fade meter at a temperature of 35 ° C., and the minimum exposure sensitivity difference (ΔSw) before and after storage was determined.

  Minimum exposure sensitivity difference (ΔSw) = Minimum exposure sensitivity after storage (S2w) −Minimum exposure sensitivity before storage (S1w)

  From the above table, it can be seen that the holographic information medium of the present invention shows a good result with no decrease in sensitivity for reproduction compared to the comparative example.

(Evaluation of coloring degree)
The holographic recording media used in Table 5 were treated for 5 minutes under a sunshine fade meter of 70,000 lux without holographic exposure, and then heat treated at 100 ° C. for 5 minutes to produce holographic information media. Subsequently, it preserve | saved on the following conditions, the transmittance | permeability of each information media was measured with the Hitachi Ltd. make and Hitachi spectrophotometer U-4100 before and after preservation | save, and the following method evaluated.

(Heat resistant storage stability)
The holographic information media was stored at 80 ° C. for 2 weeks, and the transmittance difference (ΔTh) at 400 nm before and after storage was determined.

Transmittance difference (ΔTh) = Transmittance before storage (T1h) −Transmittance after storage (T2h)
(Light-resistant storage stability)
The sample was stored for 1 week under a 70,000 lux sunshine fade meter at a temperature of 35 ° C., and the transmittance difference (ΔTh) at 400 nm before and after storage was determined.

  Transmission difference (ΔTw) = Transmission before storage (T1w) −Transmission after storage (T2w)

  From the above table, it can be seen that the holographic information medium of the present invention shows good results with less coloring compared to the comparative example.

It is the schematic which shows the principle of the measuring apparatus used for the measurement of shrinkage | contraction rate.

Explanation of symbols

01 Light emission point of white illumination light source 02 Observer's viewpoint 3 Hologram 4 White illumination light source 5 Spectrometer 6 Personal computer 7 Moving pinhole plate 8 Pinhole 9 Illumination light 11 Reproduction light

Claims (20)

A holographic recording composition comprising at least a binder-forming compound, a compound having an ethylenically unsaturated bond, and a photopolymerization initiator capable of initiating a polymerization reaction of the compound having an ethylenically unsaturated bond. As a forming compound, a compound having 3 or more isocyanate groups in the molecule in which the proportion of the isocyanate group is 30% by mass or more and 65% by mass or less in the compound is contained , and the proportion of the isocyanate group is 30% by mass in the compound above 65 wt% or less is within the molecular compound having three or more isocyanate groups, the der Rukoto 100 mass% to 5 mass% or less with respect to the entire compound having an isocyanate group contained as a binder forming compounds A holographic recording composition. The molecular weight of a compound having 3 or more isocyanate groups in a molecule in which the proportion of the isocyanate group is 30% by mass or more and 65% by mass or less in the compound is 200 or more and 500 or less. Holographic recording composition. The holographic recording composition according to claim 1, further comprising a compound having two or more hydroxyl groups in the molecule as the binder-forming compound. The holographic recording composition according to claim 3, wherein the compound having two or more hydroxyl groups in the molecule has a molecular weight of 100 or more and 2000 or less. The composition for holographic recording according to any one of claims 1 to 4, wherein the compound having an ethylenically unsaturated bond contains a compound having a (meth) acryloyl group in the molecule. The holographic recording composition according to any one of claims 1 to 5, wherein the compound having an ethylenically unsaturated bond in the molecule contains a compound having a refractive index of 1.55 or more. . The photopolymerization initiator is at least one compound selected from a bisimidazole compound, a metal π complex, and a compound represented by the following general formula (1). 2. The composition for holographic recording according to item 1.

(Where Dye ⁺ Represents a cationic dye, R ₁ ~ R ₄ Each represents a substituted or unsubstituted alkyl group, aryl group, aralkyl group, alkenyl group, alkynyl group, heterocyclic group or cyano group, and R ₁ ~ R ₄ May be bonded to each other to form a ring. ) In a holographic recording medium in which a holographic recording layer is sandwiched between a first substrate and a second substrate, the holographic recording layer has a binder-forming compound, a compound having an ethylenically unsaturated bond, and the ethylene Composed of a layer containing a photopolymerization initiator capable of initiating a polymerization reaction of a compound having a polymerizable unsaturated bond, and the proportion of the isocyanate group as the binder-forming compound is 30% by mass or more and 65% by mass or less in the compound A compound having a compound having three or more isocyanate groups in a certain molecule and having a proportion of the isocyanate group of 30% by mass or more and 65% by mass or less in the compound having three or more isocyanate groups in the molecule, 5% by mass based on the whole compound having an isocyanate group contained as a binder-forming compound The holographic recording medium, characterized in that at the upper 100 mass% or less. When the thickness of the first substrate is d1, the thickness of the second substrate is d2, and the thickness of the holographic recording layer is Dh, the relationship of 0.15 ≦ Dh / (d1 + d2) ≦ 2.0 is satisfied. The holographic recording medium according to claim 8, wherein the holographic recording medium is satisfied. The holographic recording medium according to claim 9, wherein a thickness Dh of the holographic recording layer is 200 μm or more and 2.0 mm or less. 11. The holographic recording medium according to claim 9, wherein a relationship between the thickness d1 of the first base material and the thickness d2 of the second base material satisfies d1 ≦ d2. The antireflection treatment is performed on the surface opposite to the surface on which the first base material is transparent and the holographic recording layer is laminated. Holographic recording media. The holographic recording medium according to any one of claims 8 to 12, wherein a material of the first base material is glass. 14. The reflection layer having a reflectance of 70% or more is laminated on the surface of the second base material on which the holographic recording layer is laminated or on the opposite surface thereof. Holographic recording medium as described in 1. The holographic recording medium according to any one of claims 8 to 14, wherein the holographic recording medium has a disk shape. The holographic recording medium according to claim 8, wherein the holographic recording medium has a card shape. A holographic recording layer is sandwiched between a first substrate and a second substrate, and the holographic recording layer has a binder-forming compound, a compound having an ethylenically unsaturated bond, and the ethylenically unsaturated bond It contains at least a photopolymerization initiator capable of initiating a polymerization reaction of the compound, and the proportion of the isocyanate group as the binder-forming compound is 30% by mass or more and 65% by mass or less in the molecule. A compound having a group and a compound having two or more hydroxyl groups in the molecule, and the proportion of the isocyanate group is 30% by mass to 65% by mass in the compound; 5 to the whole compound having an isocyanate group contained as a binder-forming compound Information to be recorded after forming a binder by reacting binder forming compounds with each other before holographic exposure in a method for holographic recording on a holographic recording medium having a recording layer laminated in an amount of 100% by mass or less. The photopolymerization initiator is activated by holographic exposure based on the holographic recording medium, and the active species is used to diffusely polymerize a compound having an ethylenically unsaturated bond in the holographic recording layer, thereby transferring information to the holographic recording medium. A holographic recording method characterized by recording. 18. The holographic recording method according to claim 17, wherein after the information is recorded on the holographic recording medium, the recorded information is further stabilized by performing heat and light irradiation on the entire holographic recording medium. . A holographic recording layer is sandwiched between a first substrate and a second substrate, and the holographic recording layer has a binder-forming compound, a compound having an ethylenically unsaturated bond, and the ethylenically unsaturated bond It contains at least a photopolymerization initiator capable of initiating a polymerization reaction of the compound, and the proportion of the isocyanate group as the binder-forming compound is 30% by mass or more and 65% by mass or less in the molecule. An isocyanate group containing a compound having a group, and a compound having 3 or more isocyanate groups in the molecule in which the proportion of the isocyanate group is 30% by mass to 65% by mass in the compound is contained as a binder-forming compound 5% by mass to 100% by mass with respect to the total compound having In a holographic recording method on a holographic recording medium in which a recording layer containing a compound having two or more hydroxyl groups is laminated, holographic exposure based on information to be recorded is performed to activate a photopolymerization initiator. The compound having an ethylenically unsaturated bond is diffusion-polymerized by the active species to record information on the holographic recording medium. After the information recording on the holographic recording medium is completed, the entire holographic recording medium is further heated. And a holographic recording method comprising stabilizing information recorded by light irradiation. A holographic recording layer is sandwiched between the first base material and the second base material, and the holographic recording layer has a proportion of 30% by mass to 65% by mass of the isocyanate group in the compound. A compound having three or more isocyanate groups in the molecule containing a compound having three or more isocyanate groups, and the proportion of the isocyanate groups being 30% by mass or more and 65% by mass or less in the compound is a binder-forming compound. The region containing 5% by mass or more and 100% by mass or less of the entire compound having an isocyanate group, and mainly comprising a urethane compound formed by a reaction with a compound having two or more hydroxyl groups in the molecule. And a region mainly composed of a radical polymer formed by radical polymerization of a compound having an ethylenically unsaturated bond. Holographic information media to be characterized.

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