JP4466140B2 - 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, a holographic recording method, and a holographic information medium on which information is recorded.

  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 discs and HD DVD discs is expected. 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 unattended.

  Among these next-generation recording media, page-type memory systems, especially holographic recording, have been proposed as an alternative to conventional memory devices, and are high-capacity and high-speed transfer systems that allow random access. That has attracted attention in recent years. Details of the holographic recording are described in several reviews (for example, see Non-Patent Document 1).

  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 a holographic recording layer. A recording method using a holographic recording medium provided with a reflecting surface arranged on one side of the recording medium (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 producing the recording layer forming composition, and therefore the thickness of the recording layer is about 150 μm at the maximum. Limited. 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-mentioned drawbacks, there have been proposed holographic recording layer forming compositions (for example, see Patent Document 6) that use cationic polymerization with no solvent and relatively little system shrinkage. However, since the recording layer forming composition is a liquid substance other than the monomer that causes photocationic polymerization, the island-shaped portion formed by photopolymerization of the monomer in the recording layer may move due to holographic exposure. And the volume of the liquid material expands due to the change of the environmental temperature in the apparatus.

  In order to improve such disadvantages, radical polymerization is used for recording in holographic exposure, and a composition is formed by forming a binder after media formation in order to retain the monomer capable of radical polymerization before the exposure (for example, patent documents) 7), etc., and by using such a composition, the film thickness of the holographic recording layer can be increased and the volume shrinkage can be reduced.

On the other hand, when forming a holographic recording medium, it is essential that there is no minute defect in the recording layer. However, when polyvalent isocyanate and polyhydric alcohol are used as the binder forming compound (for example, see Patent Documents 8 and 9). )), There are cases where carbon dioxide is generated by the reaction between isocyanate and water due to moisture in the polyhydric alcohol or moisture taken in from the outside during the preparation of the recording layer forming composition. In the case of harshness or harshness, air bubbles that can be discriminated with sight may be mixed, so it is necessary to pay attention to the mixing of moisture.
Hans J.H. Coufar et al., "Holographic Data Storage (Springer Series in Optical Sciences, Vol 76)" (Springer-Verlag GmbH & Co. KG, August 2000). US Pat. No. 5,719,691 JP 2002-123949 A British patent 9,929,953 JP 10-340479 A US Pat. No. 4,942,112 US Pat. No. 5,759,721 US Pat. No. 6,103,454 International Publication No. 03/014178 Pamphlet International Publication No. 03/023519 Pamphlet

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a holographic recording medium free from defects due to bubbles in the holographic recording layer, a holographic recording method, and holographically recorded holographic information. To provide media.

  The above object of the present invention can be achieved by the following configuration.

( 1 )
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 comprises a compound having two or more isocyanate groups in the molecule and an intramolecular A binder-forming compound containing at least a compound having two or more hydroxyl groups, 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, respectively. And containing 0.01 to 1.00 parts by mass of a compound represented by the following general formula (1) with respect to 100 parts by mass of the binder-forming compound to be contained. Holographic recording media.

General formula (1) M (OCOR) _n
(In the formula, M represents lead or bismuth, R represents a linear or branched alkyl group, cycloalkyl group, or substituted or unsubstituted aromatic group, n represents 1 when M is lead, and 1 represents bismuth. 3)
(Claim 2)
The holographic recording medium according to claim 1, wherein M represented by the general formula (1) is bismuth.

( 3 )
The photopolymerization initiator contained in the holographic recording layer is at least one compound selected from a bisimidazole compound, a metal π complex, and a compound represented by the following general formula (2). the holographic recording medium of the 1, wherein the.

(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 _{1 to} R ₄ may be bonded to each other to form a ring.
( 4 )
It further comprises a sensitizing dye capable of spectrally sensitizing a photopolymerization initiator capable of initiating a polymerization reaction of a compound having an ethylenically unsaturated bond contained in the holographic recording layer. The holographic recording medium according to any one of claims 1 to 3 .

( 5 )
5. The compound according to any one of 1 to 4 , wherein the compound having an ethylenically unsaturated bond contained in the holographic recording layer contains at least a compound having a (meth) acryloyl group in the molecule. Holographic recording media.

( 6 )
As a compound having an ethylenically unsaturated bond contained in the holographic recording layer, a compound having a refractive index of at least 1.55 or more is contained in an amount of 50 to 100% by mass based on the entire compound having an ethylenically unsaturated bond. The holographic recording medium according to any one of claims 1 to 5 , wherein:

( 7 )
In the holographic recording medium, when the thickness of the first base material is D1, the thickness of the second base material is D2, and the thickness of the holographic recording layer is Dh, 0.15 ≦ Dh / (D1 + D2) ≦ 2. holographic recording medium according to any one of the 1-6 characterized by satisfying the relation of 2.0.

( 8 )
In the holographic recording medium, the holographic thickness Dh of the recording layer is 200μm or more, the holographic recording medium of the 7, wherein a is 2.0mm or less.

( 9 )
In the holographic recording medium, the holographic recording medium of the 8 wherein the relationship between the thickness D2 of the thickness D1 of the first substrate the second substrate is characterized by a D1 ≦ D2.

( 10 )
In the holographic recording medium, a first substrate is transparent, one of the 1-9 holographic recording layer, characterized in that the antireflection treatment on the opposite side has been made from the laminated surface 1. A holographic recording medium according to item 1.

( 11 )
In the holographic recording medium, wherein the 1 to 1 0 holographic recording medium according to any one of, wherein the material of the first substrate is glass.

( 12 )
In the holographic recording medium, wherein the 1 to 1 1 the reflective layer reflectance of 70% or more to the surface second substrate holographic recording layer is laminated or opposite surface thereof, characterized in that it is laminated The holographic recording medium according to any one of the above.

( 13 )
The holographic recording medium according to any one of claims 1 to 12 , wherein the holographic recording medium has a disk shape.

( 14 )
The holographic recording medium according to any one of claims 1 to 12 , wherein the holographic recording medium has a card shape.

( 15 )
In the above method of recording the 1 to 1 4 holographic recording medium described in any one of after forming the binder was previously reacting the binder forming compounds holographic exposure to the holographic recording medium, the recording information desired 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.

( 16 )
16. The holographic recording method according to claim 15, wherein after the information recording on the holographic recording medium is completed, the entire holographic recording medium is further stabilized by heat and light irradiation.

( 17 )
A method of recording a holographic recording medium according to any one of the 1 to 1 4, performs holographic exposure based on information to be recorded on the holographic recording medium, activate the photoinitiator, Information is recorded on the holographic recording medium by diffusion polymerization of a compound having an ethylenically unsaturated bond with the active species. After the information recording on the holographic recording medium is completed, heat and heat are further applied to the entire holographic recording medium. A holographic recording method comprising stabilizing information recorded by irradiating light.

( 18 )
A holographic information recording layer is sandwiched between the first substrate and the second substrate, and the holographic information recording layer comprises two or more compounds having two or more isocyanate groups in the molecule and two or more in the molecule. a compound having a hydroxyl group, and a region mainly composed of urethane compound represented by crosslinked form as catalyst under following general formula (1), an ethylenically unsaturated bond having a refractive index of 1.55 or more A holographic information medium comprising: a region mainly composed of a radical polymer formed by radical polymerization containing at least a compound having a monomer as a monomer unit.
General formula (1) M (OCOR) _n
(In the formula, M represents lead or bismuth, R represents a linear or branched alkyl group, cycloalkyl group, or substituted or unsubstituted aromatic group, n represents 1 when M is lead, and 1 represents bismuth. 3)

  According to the present invention, it is possible to provide a holographic recording medium, a holographic recording method, and a holographic information medium on which holographic recording is performed, which has high sensitivity and excellent storage stability and is free from defects due to bubbles.

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

  The holographic recording medium of the present invention comprises a compound in which a holographic recording layer is sandwiched between a first substrate and a second substrate, and the holographic recording layer has two or more isocyanate groups in the molecule. A binder-forming compound containing at least a compound having two or more hydroxyl groups in the molecule, 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 And the holographic recording layer further contains at least the compound represented by the general formula (1), and by adding the compound of the general formula (1), two or more A binder having a urethane bond formed from a compound having an isocyanate group and a compound having two or more hydroxyl groups in the molecule; Not only can it be formed under mild conditions, but it can also prevent bubbles due to foaming and defects due to microscopic voids seen when using a tin-based catalyst such as butyltin dilaurate. It can be formed as a layer.

  In the general formula (1), R is preferably a linear or branched alkyl group or cycloalkyl group having 4 to 20 carbon atoms. The substituted or unsubstituted aromatic group is preferably a linear or branched alkyl group having 1 to 18 carbon atoms, and the aromatic group is preferably an aryl group or a naphthyl group. Moreover, what is represented by M is lead or bismuth, and bismuth is more preferable in consideration of the influence on the environment.

The compound represented by the general formula (1) has an addition amount of the compound represented by the general formula (1) of 0.01 parts by mass or more and 1.00 when the binder-forming compound is 100 parts by mass. It added in parts by weight or less of the range, further 0.01 parts by mass or more, more preferably below 0.50 parts by weight. If the amount added is less than 0.01 parts by weight with respect to the binder-forming compound, it is too small to induce a catalytic reaction, so it takes time to form urethane bonds, and the reaction cannot be performed under mild conditions. It is not preferable. In addition, when the addition amount is more than 1.00 parts by mass, the reaction becomes abrupt and heat is generated during the preparation of the recording layer forming composition, and further, the composition itself is thickened, making it impossible to produce a recording medium. That is not preferable.

  Next, a compound having two or more isocyanate groups in the molecule and a compound having two or more hydroxyl groups in the molecule, which are added as essential components to the recording layer of the holographic recording medium of the present invention, will be described in detail.

  A compound having two or more isocyanate groups in the molecule and a compound having two or more hydroxyl groups in the molecule are added to form a binder described in detail in the method for producing a holographic recording medium described later. Specific examples of the compound having two or more isocyanate groups in the molecule include 1,8-diisocyanate-4-isocyanatomethyl-octane, 2-isocyanatoethyl-2,6-diisocyanate caproate, benzene- 1,3,5-triisocyanate, 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, diphenylmethane-2,4,4'- Triisocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate, bis (i Cyanatotolyl) phenylmethane, dimethylene diisocyanate, tetramethylene diisocyanate, hexanemethylene diisocyanate, 2,2-dimethylpentane diisocyanate, 2,2,4-trimethylpentane diisocyanate, decane diisocyanate, ω, ω'-diisocyanate-1 , 3-dimethylbenzene, ω, ω′-diisocyanate-1,2-dimethylcyclohexane 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'-dimethyldiphenylmethane-4,4'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 3,3 '-Dimethoxydiphenylmethane-4,4'-diisocyanate, 4,4'-diethoxydiphenylmethane-4,4'-diisocyanate, tolylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, tetramethylene xylylene Diisocyanates and the like, and dimer or trimer adducts of each of the above isocyanate compounds (for example, 2 moles of hexamethylene diisocyanate, 3 moles of hexamethylene diisocyanate, 2,4-tolylene diisocyanate 2) Molar adducts, 2,4-tolylene diisocyanate, 3 molar adducts, etc.), adducts of two or more different isocyanates selected from these isocyanates, and these isocyanates and divalent or trivalent poly Adducts (eg, tolylene diisocyanate) with alcohols (eg, diethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolpropane, etc.) Adduct of trimethylol propane, etc. adduct of hexamethylene diisocyanate and trimethylolpropane) and the like. In addition, you may use these isocyanate compounds individually by 1 type or in combination of 2 or more types.

  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 used in a state where the recording is completed. As with CDs and DVs, the media may have a variety of ambient temperatures under fluorescent lamps, windows, or left. 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.

  Also, to record all information on a holographic recording medium in which a recording layer composed of a holographic recording composition, which will be described in detail later, is laminated, and to suppress coloring of the holographic information medium used in the state where the recording is completed The compound having two or more hydroxyl groups in the molecule is preferable as the compound capable of reacting with the isocyanate compound, and more preferably a compound having two or more aliphatic alcoholic hydroxyl groups in the molecule.

  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-propane. Diol, 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-decandio , 1,4-cyclohexanediol, glycerin, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc., and two alcoholic hydroxyl groups in the molecule Examples thereof include alcohols modified with divalent alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, and polytetramethylene glycol. In addition, these compounds having two or more alcoholic hydroxyl groups in the molecule may be used alone or in combination of two or more.

  In addition, the molecular weight of a compound having two or more aliphatic alcoholic hydroxyl groups in the molecule is the compound itself having volatility, a compound having an ethylenically unsaturated bond, a compound having a cationically polymerizable functional group, or photopolymerization. In consideration of the compatibility and solubility with the initiator, it is usually preferable that the molecular weight is 100 or more and 2,000 or less, and the addition amount of the compound having two or more aliphatic alcoholic hydroxyl groups in the molecule is as follows. The number of moles of isocyanate groups in the composition for holographic recording possessed by the compound having an isocyanate group is N [mol], although it cannot be generally defined by the type and amount of the isocyanate compound that is the essential component described above. The number of moles of hydroxyl group in the composition for holographic recording of the alcoholic hydroxyl group is defined as M [mol]. In a usually 0.5 ≦ N / M ≦ 2.0, more preferably more preferable from the viewpoint of the control of the compatibility or cross-linking reaction to the range of 0.7 ≦ N / M ≦ 1.5.

  As the compound having an ethylenically unsaturated bond in the molecule used in the present invention, a compound having an ethylenically unsaturated bond, for example, a styrene derivative, a compound having an allyl group, an unsaturated olefin, or the like does not impair the object of the present invention. Can be used without any particular limitation, but in consideration of adhesion to the substrate when used as a recording medium and compatibility with a binder-forming compound, a compound having an acyloxy group or acylamide group in the molecule is preferred. Further, a compound having a (meth) acryloyl group is more preferable from the viewpoint of steric hindrance during radical polymerization. In addition, the (meth) acryloyl group said by this invention represents an acryloyl group or a methacryloyl group.

  In the present invention, it is formed by reacting a compound represented by the general formula (1) described above as a catalyst with a compound having two or more isocyanate groups in the molecule and a compound having two or more hydroxyl groups in the molecule. In order to make the refractive index difference between the binder and the polymer of the compound having an ethylenically unsaturated bond obtained by diffusion polymerization more prominent, the refractive index of the compound having the ethylenically unsaturated bond is It is preferable to use a material higher or lower 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 having a high refractive index of ethylenically unsaturated bond is used as a compound having an ethylenically unsaturated bond. This is preferable because a polymer of the compound is obtained.

  As such a compound having a (meth) acryloyl group having a refractive index of 1.55 or more, generally a hetero atom such as nitrogen, oxygen, sulfur and phosphorus, a halogen atom such as chlorine, bromine and iodine in the molecule, or Specific examples of such compounds include paracumylphenoxyethylene glycol acrylate, paracumylphenoxyethylene glycol methacrylate, hydroxyethylated o-phenylphenol acrylate, hydroxyethyl, and the like. Β-naphthol acrylate, tribromomophenyl acrylate, tribromophenyl methacrylate, triiodophenyl methacrylate, polyethylene oxide modified tetrabromobisphenol A diacrylate, polyethylene oxa Modified 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. Can be mentioned.

  Further, when preparing a holographic recording layer 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, viscosity, and 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 having an ethylenically unsaturated bond in the molecule described above may be used alone or in combination of two or more, and usually 1.0% by mass or more in the composition for holographic recording. 50% by mass or less, and preferably 4.0% by mass or more and 40% by mass or less, when a compound having an ethylenically unsaturated bond is subjected to diffusion polymerization to form a polymer having a high refractive index. Preferably contains 50 to 100% by mass of the compound having a refractive index of 1.55 or more, more preferably 60 to 100% by mass, based on the whole compound having an ethylenically unsaturated bond in the molecule. More preferably.

  The photopolymerization initiator for photopolymerizing the compound having an ethylenically unsaturated bond of the present invention is not particularly limited as long as it can generate a radical by light, and conventionally known benzoin and its derivatives, benzophenone, etc. Carbonyl compounds, 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, onium compounds such as substituted or unsubstituted diphenyliodonium salts and triphenylsulfonium salts, and bisimidazole compounds such as 2,2-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole , Iron arene complexes and titanocene complexes A photopolymerization initiator such as a genus π complex can be selected and used in a timely manner, and among these, at least selected from a bisimidazole compound, a metal π complex, and a compound represented by the following general formula (2). One type of compound is more preferable from the viewpoint of sensitivity and stability, and among the metal π complexes, an iron arene complex is more preferable.

  Specific examples of such bisimidazole compounds include, for example, 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-bromo) Phenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (p-carboxyphenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2, 2'-bis (p- Anophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole, 2,2'-bis (2,4-dichlorophenyl) -4,4', 5,5'-tetraphenylbi Imidazole, 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-hexyl Enyl) -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- (betaphenoxy-ethoxyphenyl)] biimidazole, 2,2'-bis (2,6-dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-methoxyphenyl) -4,4', 5,5'-tetraphenylbiimidazole 2,2'-bis (p-methoxyphenyl) -4,4'-bis (o-methoxyphenyl) -5,5'-diphenylbiimidazole, 2,2'-bis (o-nitrophenyl)- 4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (p-phenylsulfonylphenyl) -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 -Phenanthryl) -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'-tetraphenylbiimidazole, 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'-tetraphenylbiimidazole 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'-tetraphenyl Biimidazole, 2,2′-bis (o-nitrophenyl) -4,4 ′, 5,5′-tetrakis (m-methoxyphenyl) biimidazole, 2,2′-bis (2-chloro-5-sulfone) Phophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, and the like, and “Photoinitiators or Free-Radical-Initiated Photoimaging Sy”. tems ", Chem. Rev. , 93, p. 435-448 (1993), S.A. P. P. Of Papas, “Radiation Curing: Science and Technology, Plenum Press, New York, (1992)”. 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+) hexafluorophosphate, (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+) pentafluorohydroxy Antimonate, (η6-toluene) (η5-cyclopentadienyl) iron (1+) hexafluoroarsenate, (η6-toluene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6- Naphthalene) (η5-cyclopentadienyl) iron (1+) tetrafluoroborate, (Η6-pyrene) (η5-cyclopentadienyl) iron (1+) triflate, (η6-fluorene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-hexamethylbenzene) ( η5-cyclopentadienyl) iron (1+) pentafluorohydroxyantimonate, (η6-perylene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-benzene) (η5-cyclopentadiene) Enyl) iron (1+) hexafluoroantimonate, (η6-mesitylene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimonate, (η6-mesitylene) (η5-cyclopentadienyl) iron (1+) Hexafluorophosphate, (η6-mesitylene) (η5-cyclopentadienyl) iron 1+) pentafluoro-hydroxy antimonate and (Ita6- cumene) (eta. @ 5 -cyclopentadienyl), and the like iron (1+) butyl triphenyl borate.

  Furthermore, it does not absorb the wavelength of the exposure light source used for holographic exposure, which will be described later, or does not absorb the wavelength of the laser light source used for the holographic exposure of the photopolymerization initiator. 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, coumarin derivatives, and 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, pyromethene derivatives and 2,5-thiofezyl (5-t-butyl-1) 3-benzoxazole) various dyes such as optical brightening agents, such as if individually or required may be used in combination of two or more.

  Specific examples of such photopolymerization initiators or sensitizing dyes include, for example, U.S. Pat. Nos. 5,027,436, 5,096,790, 5,147,758, and 5,204. No. 467, No. 5,256,520, No. 6,011,180, European Patent Nos. 255,486, 256,981, No. 277,915, No. 318,893, No. 401,165 Nos. 565,488, 1,349,006, JP-A-2-236553, 5-46061, 5-216227, 5-247110, 5-257279, 6- 175554, 6-175562, 6-175563, 6-175656, 6-186899, 6-195015, 6-202540, 6-202541, 6-2 2543, 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, 2002-296664, and the like. Can be selected and used at the appropriate time.

  Furthermore, the photopolymerization initiator represented by the above general formula (2) 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 present 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 general formula (2), in order to efficiently generate radicals from the 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 or 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 (2), 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 (3) are preferable.

Formula (3) Me _a ⁺ (L) _b
In the formula, Me 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 (3) is a dye that can be chelated at a bidentate or higher with respect to a 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, These carbocycles or heterocycles 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 ₅ and R ₆ 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 .

In addition, as the metal ion represented by Me _a ⁺ in the general formula (4), 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 capable of coordination in a tetradentate or hexadentate form In the case of a tridentate dye, a metal ion capable of coordinating at a 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 photopolymerization initiator for photopolymerizing the above-mentioned compound having an ethylenically unsaturated bond is generally determined by the molecular weight of the photopolymerization initiator and the proportion of the ethylenically unsaturated bond in the compound having an ethylenically unsaturated bond. However, it is usually preferable to use in the range of 0.01 to 25 parts by mass with respect to the compound having an ethylenically unsaturated bond. The addition amount of the sensitizing dye is preferably 0.01 to 25 parts by mass with respect to the photopolymerization initiator.

  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.

  The first base material and the second base material used in the recording medium of the present invention are transparent and do not cause expansion and contraction or bending at the use environment temperature, and are inactive 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 It may be a base material made of resin instead of a base material such as glass with suppressed fluctuations.

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 substrate. 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 containing fluorine atoms, modified polymers modified with functional groups containing fluorine atoms, etc. than those detailed above as substrates It is preferable because the refractive index is lowered.

  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.

  Further, for a recording medium used in a holographic recording / reproducing apparatus such as Japanese Patent Application Laid-Open No. 2002-123949 and International Publication No. 99/57719, a surface on which a second holographic recording layer is laminated. Alternatively, it is preferable that a reflective layer is provided on 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 more preferably 80% or more. More preferably.

  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 produced 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 film thickness of the holographic recording layer cannot be increased, or even if the film 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. Further, 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 the recording media, unevenness of the recording layer at the operating environment temperature, variation of the recording layer thickness when unexpected stress is applied, and further, the first base material and the second base material Is not preferable because it may shift.

  Further, 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, etc. of the recording layer, but is usually preferably 200 μm or more and 2.0 mm or less. When a recording medium having a capacity cannot be obtained and is thicker than 2.0 mm, it is not preferable because unevenness in the thickness of the recording layer may occur at the surface accuracy of the recording medium and the use environment temperature.

  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-A-2002-123949 If it is used for the apparatus described in No. etc., the disk-shaped thing is preferable, and if the apparatus described in the international publication 99/57719 etc. is used, a card-like thing is preferable.

  As a method for producing the recording medium described in detail above, a holographic recording layer forming composition is prepared by mixing the holographic recording composition by heating at room temperature or as necessary under a safelight. , After deaeration to suppress polymerization inhibition during holographic exposure, a holographic recording layer forming composition heated to room temperature or as necessary is applied on the first substrate, and then the second substrate Can be manufactured by sealing the end portion after the pasting so that bubbles do not enter so as to have a predetermined recording layer thickness. 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 produce a recording medium by filling between the first base material and the second base material by injection molding or suctioning 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 producing a recording medium by bonding, the holographic recording layer forming composition may be applied not on the first base material described above but on the second base material. You may attach to both of a 2nd base material. 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 a 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 two holographic recording layers are present in the molecule. Initiating a polymerization reaction of a binder-forming compound containing at least a compound having an isocyanate group and a compound having two or more hydroxyl groups in the molecule, a compound having an ethylenically unsaturated bond, and the compound having an ethylenically unsaturated bond In a method for holographic recording on a holographic recording medium on which a recording layer containing at least a photopolymerization initiator and a compound represented by the above general formula (1) is laminated, A compound having two or more isocyanate groups and a compound having two or more hydroxyl groups in the molecule are represented by the above general formula ( ) Is used as a catalyst to form a binder, and then a holographic exposure based on the information to be recorded is performed to activate the photopolymerization initiator. Information is recorded on a holographic recording medium by diffusion polymerization of a compound having a bond in the holographic recording layer.

  In general, when a thick film layer is attached, a recording layer forming 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 preparation of the composition. Removal becomes difficult. Therefore, fluidity is required at normal temperature or in a heated state when the recording layer forming composition is prepared. When this recording layer forming composition is liquid at room temperature and has a low viscosity, it is difficult to ensure flatness as a recording medium, or the ethylenically unsaturated bond after information is recorded by holographic exposure. It is not preferable because the polymer formed by the compound having the above may be displaced in the recording layer.

  Therefore, a compound having two or more isocyanate groups in the molecule and a compound having two or more hydroxyl groups in the molecule are essential for holographic recording media containing the above-mentioned essential components before holographic exposure. A holographic polymer formed by diffusion polymerization of a compound having an ethylenically unsaturated bond at the time of ensuring planarity and holographic exposure is obtained by crosslinking a binder-forming compound as a component. Movement within the recording layer can be prevented.

  After the binder is formed as described above, holographic exposure based on the information to be recorded is performed to activate the photopolymerization initiator, and this active species diffuses the compound having an ethylenically unsaturated bond. By doing so, information can be recorded on the holographic recording medium.

  The crosslinking reaction for forming the above-mentioned binder in the present recording method may be performed by crosslinking all combinations of functional groups capable of reacting, or may be partially crosslinked within a range that does not cause any practical problems. . Furthermore, after information is recorded on the holographic recording medium, the ethylenically unsaturated bond remaining in the recording layer by light and heat applied as necessary for the purpose of fixing the recorded holographic information. It is preferable to photopolymerize a compound having a photopolymerization initiator with a photopolymerization initiator and to thermally crosslink uncrosslinked functional groups of the remaining binder-forming compound. In this case, it is preferable that the light used for exposure is exposed all over the recording medium. When heating is performed, the exposure may be performed before the batch exposure, at the same time as the batch exposure, or after the batch exposure. You may combine.

  In a 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 two or more holographic recording layers are present in the molecule. A polymerization reaction of a compound having an isocyanate group and a binder-forming compound containing at least a compound having two or more hydroxyl groups in the molecule, a compound having an ethylenically unsaturated bond, and a compound having the ethylenically unsaturated bond Holographic recording method based on information to be recorded in a method for holographic recording on a holographic recording medium in which a recording layer containing at least a photopolymerization initiator and a compound represented by the above general formula (1) is laminated Exposure is performed to activate the photopolymerization initiator, and the active species expands the compound having an ethylenically unsaturated bond. Information is recorded on the holographic recording medium by polymerization, and after the information recording on the holographic recording medium is completed, the recorded information is stabilized by further applying heat and light to the entire holographic recording medium. It has a feature.

  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 layer forming composition is prepared, or a gel at room temperature unless shear stress is applied. Or a holographic recording medium in which a recording layer is formed by a recording layer forming composition having thixotropic properties.

  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. In order to further improve the storage stability of recorded information, a compound having an ethylenically unsaturated bond remaining in the recording layer by light and heat after recording information on the holographic recording medium can be obtained. It is preferable that the photopolymerization initiator and the uncrosslinked functional groups of the remaining binder-forming compound are thermally crosslinked. 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 US Pat. Nos. 5,719,691, 5,838,467, 6,163,391, 6,414,296, US Publication No. 2002-136143, JP-A-9-305978, JP-A-10-124872, JP-A-11-219540, JP-A-2000-98862, JP-A-2000-2988837, JP-A-2001-23169, JP-A-2002-83431. No., No. 2002-123949, No. 2002-123948, No. 2003-43904, International Publication No. 99/57719, No. 02/05270, it may be mentioned those described in the 02/75727 Patent like.

  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 substrate and a second substrate, and the holographic information recording layer has a compound having two or more isocyanate groups in the molecule. And a compound having a urethane as a main component and a compound having two or more hydroxyl groups in the molecule as a catalyst, and a refractive index of 1.55 or more. And a region mainly composed of a radical polymer formed by radical polymerization containing at least a compound having an ethylenically unsaturated bond as a monomer unit. This holographic information medium is normally handled. There is almost no coloration of the information recording layer on which the information is recorded under the conditions, so that there is almost no deterioration in reading with the reproduction 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 compound (A-1 to 6), the urethane curing catalyst (B-1 to 4), and the compound having an ethylenically unsaturated bond (C-1) used in preparing the holographic recording layer forming composition To 4), photopolymerization initiator (D-1 to 6), and sensitizing dye (E-1 to 11) are shown below.

<Binder forming compound>
(A-1) 2-isocyanatoethyl-2,6-diisocyanate caproate (A-2) polyisocyanate of hexamethylene disiciocyanate (Duranate D-101, manufactured by Asahi Kasei Corporation)
(A-3) Polyisocyanate of hexamethylene disiciocyanate (Asahi Kasei Co., Ltd., Duranate TSE-100)
(A-4) Polypropylene oxide adduct of glycerin (average molecular weight 1000: manufactured by NOF Corporation, Uniol TG-1000)
(A-5) Polypropylene glycol (average molecular weight 400: manufactured by NOF Corporation, Uniol D-400)
(A-6) Polypropylene glycol (average molecular weight 1000: manufactured by NOF Corporation, Uniol D-1000)
<Urethane curing catalyst>
(B-1) Dibutyltin dilaurate (B-2) Lead octylate (B-3) Bismuth tris (2-ethylhexanoate)
(B-4) Bismuth trislaurate <Compound having an ethylenically unsaturated bond>
(C-1) EO-modified tribromophenyl acrylate (refractive index * 1 = 1.564: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., New Frontier BR-31)
(C-2) Hydroxyethylated β-naphthol acrylate (refractive index = 1.583: manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester А-NP-1E)
(C-3) 9,9-bis (4- (2-acryloyloxyethoxy) phenyl) fluorene (refractive index = 1.615: manufactured by Osaka Gas Co., Ltd., BPEFA)
(C-4) 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 (D-1 to 6) and sensitizing dyes (E-1 to 11) are shown below.

(D-1) Titanocene photopolymerization initiator (manufactured by Ciba Specialty Chemicals Co., Ltd., Irgacure-784)
(D-2) (η6-cumene) (η5-cyclopentadienyl) iron (1+) hexafluorophosphate (D-3) (η6-cumene) (η5-cyclopentadienyl) iron (1+) hexafluoroantimony Nate (D-4) 2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole (D-5) (η6-cumene) (η5-cyclopentadienyl) Iron (1+) butyl triphenyl borate

<< Preparation of holographic recording layer forming composition >>
(Holographic recording layer forming composition 1)
Under safelight, 36.0 mg 2,6-di (t-butyl) -4-methylphenol and 67.1 mg urethane curing catalyst (above) were added to 57.82 g binder-forming compound (above A-4). Solution 1 was prepared by mixing and dissolving B-1). Separately, 7.92 g of binder-forming compound (above A-1), 23.75 g of binder-forming compound (above A-2), 8.00 g of compound having an ethylenically unsaturated bond (above C-1) And 2.00 g of the compound having an ethylenically unsaturated bond (supra C-4) were mixed and dissolved to prepare solution A, and then 0.500 g of photopolymerization initiator (supra C-1 ) Is added and dissolved, then added to the solution 1 described above, the composition prepared at the end is degassed with nitrogen, and then the gas components contained in the ultrasonic cleaner are removed, The following holographic recording layer forming composition 1 was prepared.

(Holographic recording layer forming composition 2 to 27)
In the holographic recording layer forming composition 1 described above, the solution 1 was added with the binder-forming compound and urethane curing catalyst in the addition amount shown in Table 1, and further with the sensitizing dye and 2-mercaptobenzthiazole (2MBT) shown in Table 1. ), And the holographic recording layer forming composition 1 except that the solution A was changed to the additive-forming amount of the binder-forming compound, the compound having an ethylenically unsaturated bond and the photopolymerization initiator described in Table 1. Holographic recording layer forming compositions 2 to 27 were prepared in the same manner.

<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. For the holographic recording described in Table 1, a polyethylene terephthalate sheet is used as a spacer so that the thickness (Dh) of the recording layer described in Table 2 is formed on the surface of the first base material that is not subjected to antireflection treatment. The composition is applied to the first substrate, and then the non-reflective surface of the second substrate is bonded to the holographic recording composition so as not to entrain the air layer and through a spacer. The first base material and the second base material were bonded together. Finally, the end portion was sealed with a moisture-curing adhesive, and heat-treated under the heat treatment conditions described in Table 2 to produce holographic recording media 1 to 16.

(Production method 2)
An antireflection treatment is performed on one surface of glass having a thickness of 0.5 mm (d1) 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. A second substrate was prepared by performing aluminum deposition on one side of a glass of 5 mm (d2) so that the reflectance by incident light perpendicular to the wavelength of 532 nm was 90%. Next, the holographic recording material described in Table 1 is formed by using a polyethylene terephthalate sheet as a spacer so that the thickness (Dh) of the recording layer described in Table 3 is provided on the surface of the first base material not subjected to the antireflection treatment. The recording layer forming composition is applied to the first substrate, and then the aluminum-deposited 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 first base material and the second base material were bonded together. Finally, the ends were sealed with a moisture-curing adhesive, and heat-treated under the heat treatment conditions described in Table 3 to produce holographic recording media 17 to 36.

<Recording and evaluation on holographic recording media>
(Recording on holographic recording media and evaluation 1)
A series of multiple holograms are written on the holographic recording medium manufactured as described above in accordance with the procedure described in US Pat. No. 5,719,691, and the recording layer of the holographic recording medium manufactured in accordance with the following method is used. Table 4 shows the results obtained by measuring and evaluating the uniformity, sensitivity (recording energy), and refractive index contrast.

(Uniformity within the recording layer)
The holographic recording medium immediately after the formation of the binder was observed with a night vision and a digital microscope, and the bubbles present in the recording layer were evaluated according to the following criteria.

(Visual evaluation)
Holographic recording media were observed with sight and evaluated according to the following criteria.

4: Bubbles are not visually recognized 3: Fine bubbles are visually observed 2: Bubbles having a diameter of 1.0 mm or less are visually observed 1: Bubbles having a diameter larger than 1.0 mm are visually observed (Digital microscope evaluation)
With a digital microscope (manufactured by Keyence Co., Ltd., Digital HF microscope VH-8000), the magnification is changed in several places from 1 to 3000 times, and the focal point is variably shifted from the first base material side to the second base material side. Was observed, the maximum value was measured and evaluated.

(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 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 is less mixed with bubbles and has a good sensitivity and refractive index contrast as compared with the comparative example.

(Recording on holographic recording media and evaluation 2)
Uniformity and refraction in the recording layer of the produced holographic recording medium by writing a series of multiple holograms on the produced holographic recording medium according to the procedure described in US Pat. No. 5,719,691. The ratio contrast was measured and evaluated in the same manner as in Evaluation 1 described above. Sensitivity (recording energy) was evaluated by the following method, and uniformity in the recording layer and refractive index contrast were evaluated in the same manner as in Evaluation 1. . The obtained results 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 the recording medium of the present invention is less mixed with bubbles and has a good sensitivity and refractive index contrast as compared with the comparative example.

(Recording on holographic recording media and evaluation 3)
A series of multiplexed holograms are written on the holographic recording medium produced as described above according to the procedure described in JP-A-2002-123949, and the sensitivity (recording energy) is measured and evaluated according to the following method. The uniformity in the recording layer was evaluated by the same method as in 1. The obtained results 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 (S2). As measured.

  From the above table, it can be seen that the recording medium of the present invention is less mixed with bubbles and has a good sensitivity and refractive index contrast as compared with the comparative example.

(Recording on holographic recording media and evaluation 4)
Uniformity and refraction in the recording layer of the produced holographic recording medium by writing a series of multiple holograms on the produced holographic recording medium according to the procedure described in US Pat. No. 5,719,691. The measurement and evaluation of the rate contrast were performed in the same manner as in Evaluation 1 described above, and the sensitivity (recording energy) was evaluated by the following method. The results obtained are shown in Table 7.

(Measurement of sensitivity)
A digital pattern is displayed on a holographic recording medium with a blue-violet semiconductor laser (405 nm) on a holographic recording medium under safe light, and this digital pattern is 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, a semiconductor laser (405 nm) in the blue-violet region is used as reference light, and the generated reproduction light is read by a CCD, and the minimum exposure amount at which a good digital pattern can be reproduced is determined with sensitivity ( Measured as S3).

  From the above table, it can be seen that the recording medium of the present invention is less mixed with bubbles and has a good sensitivity and refractive index contrast as compared with the comparative example.

(Recording on holographic recording media and evaluation 5)
A series of multiple holograms is written on the holographic recording medium produced as described above according to the procedure described in JP-A-2002-123949, and the sensitivity (recording energy) is evaluated in the same manner as in Evaluation 1 by the following method. The uniformity in the recording layer was evaluated. The obtained results are shown in Table 8.

(Measurement of sensitivity)
A digital pattern is displayed on a holographic recording medium with a blue-violet semiconductor laser (405 nm) on a holographic recording medium under safe light, and this digital pattern is 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, a semiconductor laser (405 nm) in the blue-violet region is used as reference light, and the generated reproduction light is read by a CCD, and the minimum exposure amount at which a good digital pattern can be reproduced is determined with sensitivity ( Measured as S4).

  From the above table, it can be seen that the recording medium of the present invention is less mixed with bubbles and has a good sensitivity and refractive index contrast as compared with the comparative example.

(Evaluation of holographic information media)
The holographic information media of the present invention produced by fixing the recorded information was stored under the following conditions, and a digital pattern was reproduced and evaluated by a method suitable for each information medium before and after the storage, and a good digital pattern could be reproduced. The difference in the minimum exposure amount before and after storage was evaluated by the following method, and the obtained results are shown in Table 9. 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 10.

(Heat resistant storage stability)
The holographic information media was stored at 50 ° 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 sunshine fade meter of 70,000 lux at a temperature of 25 ° 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)
(Evaluation of coloring degree)
The produced holographic recording media were treated for 5 minutes under a sunshine fade meter of 70,000 lux without holographic exposure, and then heated 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 little coloring and no reduction in sensitivity for reproduction.

Claims (18)

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 comprises a compound having two or more isocyanate groups in the molecule and an intramolecular A binder-forming compound containing at least a compound having two or more hydroxyl groups, 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, respectively. And containing 0.01 to 1.00 parts by mass of a compound represented by the following general formula (1) with respect to 100 parts by mass of the binder-forming compound to be contained. Holographic recording media.
General formula (1) M (OCOR) _n
(In the formula, M represents lead or bismuth, R represents a linear or branched alkyl group, cycloalkyl group, or substituted or unsubstituted aromatic group, n represents 1 when M is lead, and 1 represents bismuth. 3 represents a.) The holographic recording medium according to claim 1, wherein M represented by the general formula (1) is bismuth. The photopolymerization initiator contained in the holographic recording layer is at least one compound selected from a bisimidazole compound, a metal π complex, and a compound represented by the following general formula (2). holographic recording medium according to claim 1 Symbol mounting to.

( 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 _{1 to} R ₄ may be bonded to each other to form a ring. It further comprises a sensitizing dye capable of spectrally sensitizing a photopolymerization initiator capable of initiating a polymerization reaction of a compound having an ethylenically unsaturated bond contained in the holographic recording layer. The holographic recording medium according to any one of claims 1 to 3 . 5. The compound according to claim 1 , wherein the compound having an ethylenically unsaturated bond contained in the holographic recording layer contains at least a compound having a (meth) acryloyl group in the molecule. The holographic recording medium described. As a compound having an ethylenically unsaturated bond contained in the holographic recording layer, a compound having a refractive index of at least 1.55 or more is contained in an amount of 50 to 100% by mass based on the entire compound having an ethylenically unsaturated bond. The holographic recording medium according to claim 1, wherein: In the holographic recording medium, when the thickness of the first base material is D1, the thickness of the second base material is D2, and the thickness of the holographic recording layer is Dh, 0.15 ≦ Dh / (D1 + D2) ≦ 2. The holographic recording medium according to claim 1, wherein a relationship of 0.0 is satisfied . 8. The holographic recording medium according to claim 7 , wherein a thickness Dh of the holographic recording layer is 200 μm or more and 2.0 mm or less . 9. The holographic recording medium according to claim 8 , wherein the relationship between the thickness D1 of the first base material and the thickness D2 of the second base material satisfies D1 ≦ D2 . In the holographic recording medium, a first substrate is transparent, one of the claims 1 to 9 holographic recording layer, characterized in that the antireflection treatment on the opposite side has been made from the laminated surface holographic recording medium of one of claims. The holographic recording medium according to claim 1, wherein the material of the first base material is glass . 12. The holographic recording medium, wherein a reflective layer having a reflectance of 70% or more is laminated on a surface of the second substrate on which the holographic recording layer is laminated or on the opposite surface. The holographic recording medium according to any one of the above. The holographic recording medium according to claim 1, wherein the holographic recording medium has a disk shape . Holographic recording medium of any one of claims 1 to 1 2, characterized in that the shape of the holographic recording medium is card-shaped. 15. The method for recording on a holographic recording medium according to claim 1, wherein the information to be recorded after reacting a binder forming compound to form a binder before holographic exposure to the holographic recording medium. 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. 16. The holographic recording method according to claim 15 , wherein after the information recording on the holographic recording medium is completed, the entire holographic recording medium is further stabilized by heat and light irradiation . The method for recording on a holographic recording medium according to any one of claims 1 to 14, wherein holographic exposure based on information to be recorded on the holographic recording medium is performed, and a photopolymerization initiator is activated, Information is recorded on the holographic recording medium by diffusion polymerization of a compound having an ethylenically unsaturated bond with the active species. After the information recording on the holographic recording medium is completed, heat and heat are further applied to the entire holographic recording medium. features and sulfo ii graphic recording method to stabilize the information recorded by performing light irradiation. A holographic information recording layer is sandwiched between the first substrate and the second substrate, and the holographic information recording layer comprises two or more compounds having two or more isocyanate groups in the molecule and two or more in the molecule. A region mainly composed of urethane formed by crosslinking using a compound represented by the following general formula (1) as a catalyst, and an ethylenically unsaturated bond having a refractive index of 1.55 or more. A holographic information medium comprising a region mainly composed of a radical polymer formed by radical polymerization containing at least a compound having a monomer unit as a monomer unit.
General formula (1) M (OCOR) _n
(In the formula, M represents lead or bismuth, R represents a linear or branched alkyl group, cycloalkyl group, or substituted or unsubstituted aromatic group, n represents 1 when M is lead, and 1 represents bismuth. 3)