JP2005055636A - Optical recording medium, recording method therefor, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium superior in sensitivity and proper contraction resistance and contrast, and to provide its recording method and its manufacturing method. <P>SOLUTION: The optical recording medium contains a compound, having cation polymerizable group as an iron arene complex compound expressed by a general formula: [A-Fe-B]<SP>+</SP>×X<SP>-</SP>as a polymerization initiator is regarded as a polymerization substance and a compound having a radical polymerizable group. In the formula, A represents cyclopentadienyl group or alkyl substituted cyclopentadienyl group, B represents arene, and X<SP>-</SP>represents anion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel optical recording medium, a recording method thereof and a manufacturing method thereof, and more particularly to an optical recording medium suitable as a holographic recording medium, a recording method thereof and a manufacturing method thereof.

  Developers of information storage devices and methods continue to seek to increase storage capacity. As part of this development, page-based memory systems, particularly holographic systems, have been proposed as an alternative to conventional memory devices. A page-based system relates to storage and retrieval of entire two-dimensional pages of data. In particular, the recording light passes through a two-dimensional array of dark transparent regions representing a page of data, and the holographic system converts the holographic representation of the page into a varying refractive index and / or absorption pattern imprinted on the storage medium. As a three-dimensional memory.

  The holographic system is described in D.C. Pholtis et al., “Holographic Memory” (Scientific American, November 1995) generally describe. One method of holographic storage is phase correlation multiplex holography, which is described in US Pat. No. 5,719,691. In phase correlation multiplex holography, a reference light beam passes through a phase mask and intersects with a signal beam that has passed through an array representing data in a recording medium to form a hologram in the medium. The relationship between the phase mask and the reference beam is adjusted for each successive page of data, thereby modulating the phase of the reference beam and allowing data to be stored in overlapping areas in the medium. Later, this data is reconstructed by passing the reference beam through the original storage location with the same phase modulation used during data storage.

  The functionality of the holographic storage system is limited in part by the storage medium. As a storage medium for research purposes, iron-doped lithium niobate has been used for many years. However, lithium niobate is expensive and insensitive and tends to generate noise during the reading of stored information.

  Accordingly, alternatives have been sought in particular in the field of photosensitive polymer films. For example, W.W. K. The materials described by Smothers et al., "Photopolymers for Holography" (SPIE OE / Laser Conference, 1212-03, Los Angeles, CA, 1990) provide a matrix that is substantially inert to exposure light. Among the organic polymers is a photoimaging system of a liquid monomer material and a photoinitiator that promotes monomer polymerization when exposed to light. While writing information to the material (by passing the recording light through an array representing the data), the monomer polymerizes in the exposed areas. As a result, the monomer concentration is low so that the monomer in the dark unexposed areas of the material diffuses into the exposed areas. The resulting concentration gradient resulting from polymerization and the resulting refractive index changes forms a hologram containing data. However, since the deposition of the pre-formed matrix material including the photoimaging system requires the use of a solvent, the thickness of the material is limited to only about 150 μm, for example, to allow proper vaporization of the solvent. . Furthermore, the 4-10% material shrinkage caused by polymerization has a detrimental effect on the reliability of data retrieval.

  JP-A-11-352303 relates to a polymer holographic medium. The medium is formed by mixing a monomer, oligomer matrix precursor and a photoactive monomer and curing the mixture, (a) the matrix is formed from the monomer, oligomer, and (b) the monomer. At least a portion remains unreacted so that it can be used for holographic recording. Since no solvent is required for the welding of these materials (since the mixture is a liquid), it is possible to increase the thickness to, for example, 1 mm or more.

  Attempts have also been made to provide photoimaging systems that include monomers within a glass matrix. For example, a photoimage forming system including a glassy hybrid inorganic organic three-dimensional matrix and including one or more photoactive organic monomers therein has been proposed (see, for example, Patent Document 1). The medium is manufactured by providing a hybrid inorganic organic matrix precursor, mixing the matrix precursor with a photoimaging system, and curing the matrix precursor to form the matrix in situ. Glass matrices provide the desired structural integrity, as opposed to media containing polymer matrices, and allow the formation of relatively thick (eg, greater than 1 mm) optical recording media useful for holographic storage systems. To do.

  In any of the above, the optical recording material is a radical polymerization material, and the shrinkage of the material accompanying the polymerization is particularly a problem. For this problem, proposals have been made to use a cationic polymerizable optical recording material (for example, patents). Reference 2). However, this system loses merits such as less recording energy required for optical recording, which is a merit of the radical polymerization system.

Thus, while the development of optical recording media suitable for use in holographic storage systems has progressed, further improvements are required. In particular, it is chemically and structurally excellent, can form a relatively thick layer (for example, more than 1 mm) without complicated chemical treatment, can be recorded with relatively low optical recording energy, and can be used for optical recording. There is a demand for a medium that does not cause problems such as material shrinkage.
JP-A-11-344917 JP-T-2001-523842

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical recording medium excellent in sensitivity, excellent in shrinkage resistance and contrast, a recording method thereof, and a manufacturing method thereof.

Based on various studies, the present inventors have used a composition comprising a cyclic ether having a specific structure as a composition for use in an optical recording medium, while a matrix-forming substance is a monomer or oligomer composition prior to welding. The present invention has been completed by finding that the above problems can be solved when a composition for forming a matrix is used for an optical recording medium by being used as a matrix precursor and cured after welding. That is, the above object of the present invention is achieved by the following configuration.
(Claim 1)
An iron arene complex compound represented by the following general formula (A) as a polymerization initiator contains both a compound having a group capable of cationic polymerization and a compound having a group capable of radical polymerization as a polymerizable substance. Optical recording medium.

Formula (A) [A-Fe- B] + · X -
In the formula, A represents a cyclopentadienyl group or an alkyl-substituted cyclopentadienyl group, B represents an arene, and X ⁻ represents an anion.
(Claim 2)
2. The optical recording medium according to claim 1, wherein the compound having a group capable of cationic polymerization is a compound having 1 to 4 oxetane rings.
(Claim 3)
Cationic epoxy polymerization, cationic vinyl ether polymerization, cationic alkenyl ether polymerization, cationic allene ether polymerization, cationic ketene acetal polymerization, epoxy-amine step polymerization, epoxy-mercaptan step polymerization, unsaturated ester-amine step polymerization, unsaturated ester-mercaptan step polymerization 3. The optical recording medium according to claim 1, wherein the matrix is formed by at least one polymerization reaction selected from vinyl-silicon hydride step polymerization, isocyanate-hydroxyl step polymerization, and isocyanate-amine step polymerization.
(Claim 4)
4. The optical recording medium according to claim 3, wherein the matrix is formed by curing an inorganic or organic matrix precursor.
(Claim 5)
5. The optical recording medium according to claim 4, wherein the matrix precursor is derived from a compound represented by the following general formula (P).

Formula (P) R _n M (OR ′) _4-n
In the formula, M represents a metal element having a valence of 3 or more, R represents an alkyl group or an allyl group, R ′ represents a lower alkyl group having 4 or less carbon atoms, and n represents an integer of 1 or 2. Represent.
(Claim 6)
6. The optical recording medium according to claim 5, wherein M in the general formula (P) is a metal element selected from silicon, titanium, germanium, zirconium, vanadium and aluminum.
(Claim 7)
7. A recording method for an optical recording medium, wherein holographic recording is performed by irradiating the optical recording medium according to any one of claims 1 to 6 with an actinic ray.
(Claim 8)
A method for producing an optical recording medium according to any one of claims 1 to 6, comprising a step of mixing a matrix-forming substance and a step of curing the matrix precursor to form a matrix. A method for manufacturing an optical recording medium.

  Hereinafter, the present invention will be described in order with respect to components of an optical recording medium, a recording method thereof, and a manufacturing method thereof.

(Iron arene complex compound)
In the general formula (A), examples of the arenes represented by B include benzene, toluene, xylene, cumene, naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, biphenyl, fluorene soot and the like. Examples of the anion represented by X ⁻ include PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , AlF ₄ ⁻ , CF ₃ SO ₃ ^{− and the} like.

  Although the example of a preferable specific compound is given to the following, it is not limited to these.

  The iron arene complex compound is preferably contained in a proportion of 0.1 to 20% by mass, more preferably based on the total amount of the compound having a group capable of cationic polymerization and the compound having a group capable of radical polymerization. It is 0.1-10 mass%.

(Compound having a group capable of cationic polymerization)
As the compound having a cationically polymerizable group used in the present invention, a compound having an oxetane (trimethylene oxide) ring is preferable. In particular, those having 1 to 4 oxetane rings are advantageous. If a compound having 5 or more oxetane rings is used, the fluidity of the composition may be lost and may not be suitable for printing.

  Any compound having 1 to 4 oxetane rings can be used. Specific examples of the compound having one oxetane ring include compounds represented by the following general formula (1).

In the formula, R ¹ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, or furyl. Represents a group or a thienyl group. R ² is an alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group or butyl group, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl- Such as 2-propenyl group, 1-butenyl group, 2-butenyl group or 3-butenyl group, such as alkenyl group having 2 to 6 carbon atoms, phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group, phenoxyethyl group, etc. A group having an aromatic ring, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethylcarbonyl group, a propylcarbonyl group or a butylcarbonyl group, an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethoxycarbonyl group, a propoxycarbonyl group or a butoxycarbonyl group; Alkoxycarbonyl group, ethylcarbamoyl group, propylcarbamoyl group, butylcarbamo It represents an N- alkylcarbamoyl group having a carbon number 2-6 such as Le group or pentyl carbamoyl group.

  Next, examples of the compound having two oxetane rings include a compound represented by the following general formula (2).

Wherein, R ¹ has the same meaning as R ¹ in the general formula (1). R ³ is a linear or branched alkylene group such as an ethylene group, a propylene group or a butylene group, or a linear or branched poly (alkyleneoxy) such as a poly (ethyleneoxy) group or a poly (propyleneoxy) group. ) Group, a propenylene group, a methylpropenylene group or a butenylene group or a linear or branched unsaturated hydrocarbon group, a carbonyl group, an alkylene group containing a carbonyl group, an alkylene group containing a carboxyl group, or a carbamoyl group Represents an alkylene group. R ³ may be a polyvalent group represented by the following general formulas (3), (4) and (5).

In the formula, R ⁴ is an alkyl group having 1 to 4 carbon atoms such as a hydrogen atom, a methyl group, an ethyl group, a propyl group, or a butyl group, a C 1 to C 1 such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group. 4 alkoxy groups, a halogen atom such as a chlorine atom or a bromine atom, a nitro group, a cyano group, a mercapto group, a lower alkyl carboxyl group, a carboxyl group or a carbamoyl group.

In the formula, R ⁵ represents an oxygen atom, a sulfur atom, a methylene group, —NH—, —SO—, —SO ₂ —, —C (CF ₃ ) ₂ — or —C (CH ₃ ) ₂ —.

In the formula, R ⁶ represents an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, or an aryl group, and n represents an integer of 0 to 2,000. R ⁷ represents an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, or an aryl group. R ⁷ may be a polyvalent group represented by the following general formula (6).

In the formula, R ⁸ represents an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, or an aryl group, and m represents an integer of 0 to 100.

  Specific examples of the compound having two oxetane rings include the following compounds.

Exemplary compound OX-1 is a compound in which R ¹ is an ethyl group and R ³ is a carboxyl group in the general formula (2). OX-2 is a compound in which R ¹ is an ethyl group, R ³ is a general formula (5), R ⁶ and R ⁷ are methyl groups, and n is 1 in the general formula (2).

As a compound having two oxetane rings, a preferred example other than the above compound is a compound represented by the following general formula (7). R ¹ in the general formula (7) are the same as R ¹ in the general formula (1).

  Examples of the compound having 3 to 4 oxetane rings include compounds represented by the following general formula (8).

Wherein, R ¹ has the same meaning as R ¹ in the general formula (1). R ⁹ represents, for example, a branched alkylene group having 1 to 12 carbon atoms such as groups represented by the following A to C, a branched poly (alkyleneoxy) group such as a group represented by the following D, or the following E And branched polysiloxy groups such as the above-mentioned groups. j represents an integer of 3 or 4.

In the above A, R ¹⁰ represents a lower alkyl group such as a methyl group, an ethyl group or a propyl group. In D, p represents an integer of 1 to 10.

  As an example of a compound having 3 to 4 oxetane rings, the following OX-3 may be mentioned.

  Furthermore, examples of the compound having 1 to 4 oxetane rings other than those described above include compounds represented by the following formula (9).

Wherein, R ⁸ has the same meaning as R ⁸ in the general formula (6). R ¹¹ represents an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, or a trialkylsilyl group, and r represents an integer of 1 to 4.

  Preferred examples of the oxetane compound used in the present invention also include the following compounds.

  The method for synthesizing each compound having an oxetane cocoon described above is not particularly limited, and may be based on a conventionally known method. For example, Pattison (DB Patson, J. Am. Chem. Soc., 3455, 79 ( 1957)), and a method for synthesizing oxetane soot from a diol.

  In addition to these, compounds having 1 to 4 oxetane rings having a high molecular weight of about 1,000 to 5,000 are also exemplified. Specific examples thereof include the following compounds.

  Examples of the other compound having a group capable of cationic polymerization include a compound having an epoxy group and a compound having a vinyl ether group.

  Various compounds having an epoxy group can be used. For example, examples of the epoxy compound having one epoxy group include phenyl glycidyl ether and butyl glycidyl ether, and examples of the epoxy compound having two or more epoxy groups include hexanediol diglycidyl ether, tetraethylene glycol diglycidyl ether, and trimethylol. Examples thereof include propane triglycidyl ether, bisphenol A diglycidyl ether, and a novolac type epoxy compound. In particular, in the present invention, it is preferable to use an alicyclic epoxy compound, and examples thereof include the following compounds.

  These epoxy compounds can further improve the curing rate of the composition when used in combination with the compounds having 1 to 4 oxetane rings. In this case, the mixing ratio of the compound having an epoxy group is preferably 5 to 95 parts by mass with respect to 100 parts by mass in total of the compound having 1 to 4 oxetane rings and the compound having an epoxy group.

  Various compounds having a vinyl ether group can be used. Examples of the compound having one vinyl ether group include hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, dodecyl vinyl ether, propenyl ether propylene carbonate, cyclohexyl vinyl ether, and the like. Examples of the compound having two or more vinyl ether groups include cyclohexane dimethanol divinyl ether, triethylene glycol divinyl ether, and novolak divinyl ether.

  These compounds having a vinyl ether group can further improve the curing rate of the composition when used in combination with the compounds having 1 to 4 oxetane rings. In this case, the mixing ratio of the compound having a vinyl ether group is preferably 5 to 95 parts by mass with respect to a total of 100 parts by mass of the compound having 1 to 4 oxetane rings and the compound having a vinyl ether group.

(Compounds having radically polymerizable groups)
As the compound having a radical polymerizable group used in the present invention, various compounds having a (meth) acryloyl group can be used. For example, examples of the compound having one (meth) acryloyl group include (meth) acrylates of phenol, nonylphenol and 2-ethylhexanol, and (meth) acrylates of alkylene oxide adducts of these alcohols. Examples of the compound having two (meth) acryloyl groups include di (meth) acrylate of bisphenol A, isocyanuric acid, ethylene glycol and propylene glycol, and di (meth) acrylate of an alkylene oxide adduct of these alcohols. Examples of 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. Moreover, conventionally known acrylic monomers / oligomers such as urethane acrylate having a urethane bond as the main chain, polyester acrylate having an ester bond as the main chain, and epoxy (meth) acrylate obtained by adding acrylic acid to an epoxy compound are also included.

  By adjusting the compounding ratio of the compound having a (meth) acryloyl group, adjustment of the composition viscosity, modification of the coating film hardness of the composition, adjustment of the refractive index contrast, and the like can be performed.

  The blending ratio of the compound having a (meth) acryloyl group is preferably 5 to 95 parts by mass with respect to a total of 100 parts by mass of the compound having a cationic polymerizable group and the compound having a (meth) acryloyl group.

(Other compounds)
In addition to the above essential components, other components can be blended in the optical recording medium of the present invention as necessary.

  In addition to the iron arene complex compound, various photocationic polymerization initiators can be used in combination. Preferred examples of the photocationic polymerization initiator include diaryl iodonium salts and triarylsulfonium salts. It is a compound shown by the following general formula [a]-[d].

In the formula, R ¹² represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms or an alkoxy group having 1 to 18 carbon atoms, R ¹³ represents a hydrogen atom, a hydroxyalkyl group or a hydroxyalkoxy group, preferably a hydroxyethoxy group It is. M represents a metal atom, preferably antimony. X represents a halogen atom, preferably fluorine, and k is a valence of a metal atom, for example, 5 in the case of antimony.

  In addition to the iron arene complex compound, various radical photopolymerization initiators can be used in combination. Preferred are benzophenone and its derivatives, benzoin alkyl ether, 2-methyl [4- (methylthio) phenyl] -2-morpholino-1-propanone, benzyldimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2- Examples include methyl-1-phenylpropan-1-one, alkylphenylglyoxylate, diethoxyacetophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, and acylphosphine oxide. be able to.

  In the optical recording medium, in addition to the above components, inerts such as inorganic fillers, dyes, viscosity modifiers, treating agents, organic solvents and ultraviolet light blocking agents in amounts up to 100 parts by weight per 100 parts by weight of curable component Ingredients can be blended.

  Inorganic fillers include metals / non-metals such as zinc oxide, aluminum oxide, antimony oxide, calcium oxide, chromium oxide, tin oxide, titanium oxide, iron oxide, copper oxide, lead oxide, bismuth oxide, magnesium oxide and manganese oxide. Oxides, hydroxides such as aluminum hydroxide, ferrous hydroxide and calcium hydroxide, salts such as calcium carbonate and calcium sulfate, silicon compounds such as silicon dioxide, natural pigments such as kaolin, bentonite, clay and talc, Examples thereof include minerals such as natural zeolite, Oya stone, natural mica and ionite, synthetic inorganic materials such as artificial mica and synthetic zeolite, and various metals such as aluminum, iron and zinc.

  In addition to the photocationic polymerization initiator and / or the photoradical polymerization initiator, a photosensitizer can be added to match the wavelength of the light source used for recording. Known sensitizers are used, and specific examples include pyrene, perylene, acridine orange, thioxanthone, 2-chlorothioxanthone, benzoflavin, eosin, rose bengal, erythrosine, and methylene blue.

  In the present invention, examples of the polymerization reaction for forming the matrix polymer include cationic epoxy polymerization, cationic vinyl ether polymerization, cationic alkenyl ether polymerization, cationic allene ether polymerization, cationic ketene acetal polymerization, epoxy-amine step polymerization, epoxy-mercaptan step polymerization. Unsaturated ester-amine step polymerization (by Michael addition), unsaturated ester-mercaptan step polymerization (by Michael addition), vinyl-silicon hydride step polymerization (hydrosilylation), isocyanate-hydroxyl step polymerization (urethane formation) and isocyanate- There is an amine step polymerization (urea formation).

The above reaction is enabled or facilitated by a suitable catalyst. For example, cationic epoxy polymerization occurs fast at room temperature using a catalyst based on BF ₃ , other cationic polymerization proceeds in the presence of protons, and the epoxy-mercaptan reaction and Michael addition are promoted by a base such as an amine, Hydrosilylation proceeds rapidly in the presence of a transition metal catalyst such as platinum, and urethane and urea formation proceeds rapidly when a tin catalyst is used. It is also possible to use a photogenerating catalyst for matrix formation if measures are taken to prevent polymerization of the photoactive monomer during photogeneration.

  Another matrix formation typically occurs by known mechanisms of alkoxide sol-gel chemistry. For example, C.I. J. et al. See Brinker et al., "Sol-gel science-physics and chemistry of sol-gel processing" (Academic Press, 1990). In accordance with standard alkoxide sol-gel chemistry, the curing of the trifunctional oligomer precursor includes further condensation, whereby the precursor forms a three-dimensional network. The organic portion applied to the base of the final cured matrix affects the properties of the media (flexibility, impact resistance, thermal shock resistance, refractive index, density, wear resistance, etc.). A combination of organic moieties (eg both methyl and phenyl) can be used to provide the desired properties. For example, methyl increases the compatibility of the matrix precursor with the photoimaging system and allows the use of a mild cure state. Phenyl groups also provide this compatibility, although the rate of cure is reduced. Due to the large size of the phenyl, the phenyl group increases the free volume and lowers the network density of the matrix compared to a matrix with only methyl moieties. Low net density facilitates diffusion of photoactive organic monomers during data writing and gives the matrix some flexibility (if the matrix precursor is derived from hydrolysis and condensation of trifunctional organoalkoxysilanes) Incorporation of dimethylsilyl groups in the matrix base also enhances diffusion, which also improves thermal shock resistance but decreases the matrix condensation rate). Organic moieties that are removed in the condensation reaction typically affect the rate of matrix formation. For example, following the known tendency of slower reaction times for larger alkoxy groups, precursors with methoxy groups typically react faster than precursors with larger ethoxy groups.

  As an option, the matrix precursor is pre-cured prior to mixing with the photoimaging system, ie further condensed in the case of oligomeric matrix precursors. If precuring is used to promote the condensation of the matrix precursor, a more gradual final cure of the matrix precursor / photoimaging system mixture is generally required, which is substantially This is because it is carried out with an oligomer condensed to the above. A more moderate cure is advantageous in that damage to the photoimaging system, such as heat-induced premature polymerization of photoactive monomers, is generally reduced. Early cure is performed to the extent that allows substantial diffusion of the photoimaging system in the early cure precursor, but the conditions for early cure will vary depending on the particular hybrid matrix precursor. In addition, an organic solvent such as acetone can be added to dilute the precursor after premature curing. Typically, the early cure is performed at a temperature in the range of 100-200 ° C. for less than 1 hour. The control sample easily provides information about acceptable conditions for early cure.

  Prior to mixing the matrix precursor (whether precured or not) and the photoimaging system, the viscosity of the precursor is typically adjusted to about 0.1 Pa · s or less by the addition of a solvent. Encourage mixing. It is possible to adjust the viscosity by applying heat or using a solvent.

  Suitable solvents for the present invention include alkanols having up to 4 carbon atoms and ketones having up to 4 carbon atoms. Here, the alkanol and ketone can be vaporized from the matrix precursor material / photoimaging system mixture at a temperature of less than about 80 ° C. Acetone is particularly useful for a wide variety of matrix precursor materials, particularly those having a siloxane-based foundation. If a solvent is used, the solvent is typically first mixed with the matrix precursor to reduce the viscosity of the precursor, and then the photoimaging system is mixed with the solvated precursor. Solvents are particularly useful when the matrix precursor is precured because precuring increases the viscosity of the matrix material. When mixed, the matrix precursor and the photoimaging system effectively form a solution of the photoimaging system in the solvated matrix precursor. Solvent lumps are removed by heating slowly under vacuum, which further encourages matrix condensation. This process is discontinued when the desired mass is obtained.

Examples of the active energy rays include ultraviolet rays, visible rays, X-rays, and electron beams. As a light source that can be used for curing by ultraviolet rays or visible rays, various light sources can be used, for example, pressurized or high-pressure mercury lamp, metal halide lamp, xenon lamp, electrodeless discharge lamp, carbon arc lamp, laser, or LED. Etc. In the case of curing with an electron beam, various irradiation devices can be used, such as a cockloftwaldsin type, a bandegraph type, or a resonance transformer type. An electron beam having an energy of 50 to 1000 eV is preferable. More preferably, it is 100-300 eV. In the present invention, for example, GaN-based ultraviolet laser (400 to 415 nm), Ar ⁺ (458, 488, 514 nm) and He—Cd laser (442 nm) blue and green rays, frequency doubled YAG laser (532 nm), He − It is preferable to use Ne (633 nm), Kr ⁺ laser (647 and 676 nm) or the like.

  Next, the basic configuration of the holography system according to the recording method of the present invention will be described.

  FIG. 1 is a schematic diagram showing a basic configuration of a holography system 10. System 10 includes a modulator 12, an optical recording medium 14, and a sensor 16. The modulation device 12 may be any device as long as it can optically represent data in two dimensions. Device 12 is typically a spatial light modulator attached to an encoding unit that encodes data on the modulator. Based on the encoding, the device 12 selectively passes or blocks a portion of the signal beam 20 that passes through the device 12. In this way, the signal beam 20 is encoded with the data image. The image is stored at some location on or in the optical storage medium 14 by interfering with the encoded signal beam 20 and the reference beam 22. This interference creates an interference pattern (ie, a hologram) and is stored as a pattern of refractive index that changes within the optical recording medium 14. It is also possible to store one or more holographic images in one place, or to store a plurality of holograms in an overlapping state by changing the angle, wavelength or phase of the reference beam 22 with the reference beam used. . The signal beam 20 typically passes through the lens 30 before intersecting the reference beam 22 within the optical recording medium 14. It is possible for the reference beam 22 to pass through the lens 32 before this intersection. Once the data is stored in the optical recording medium 14, it is possible to retrieve the data by crossing the reference beam 22 at the same location on the optical recording medium 14 at the same angle, wavelength or phase as during data storage. is there. The reconstructed data passes through the lens 34 and is detected by the sensor 16. The sensor 16 is, for example, a charge coupled device or an active pixel sensor. The sensor 16 is typically attached to a unit that demodulates data.

  According to the present invention, it is possible to provide an optical recording medium excellent in sensitivity, excellent in shrink resistance and contrast, a recording method thereof, and a manufacturing method thereof.

  Examples Hereinafter, the present invention will be described more specifically by way of examples. However, embodiments of the present invention are not limited to these examples. In the examples, “%” indicates “mass%”.

<Preparation of optical recording medium 1>
Preparation liquid 1 comprising the following composition was poured onto a glass slide surrounded by a Teflon (R) spacer having a thickness of about 500 μm and a diameter of 25 mm, and another glass slide was then placed thereon. After leaving at room temperature for about 24 hours, an optical recording medium 1 of the present invention was obtained.
(Preparation solution 1)
"Optical recording material"
Oxetane compound (OX-5) 5%
Epoxy compound (EP-1) 5%
Urethane methacrylate 5%
Polymerization initiator: Irgacure 261 (manufactured by Ciba Specialty Chemicals)
1%
Sensitizer: Ethyleosin 0.06%
"Matrix precursor"
Diisocyanate-terminated polypropylene glycol (molecular weight = 247)
68.6%
α, ω-dihydroxypolypropylene glycol (molecular weight = 425)
13.08%
Catalyst: Dibutyltin dilaurate 0.1%
Irgacure 261: η ⁵ -cyclopentadienyl-η ⁶ -cumene iron hexafluorophosphate (same as A-1)

<Preparation of optical recording medium 2>
An optical recording medium 2 of the present invention was obtained in the same manner as the optical recording medium 1 except that the preparation liquid 2 having the following composition was used instead of the preparation liquid 1.
(Preparation solution 2)
"Optical recording material"
Oxetane compound (OX-4) 5%
Epoxy compound (EP-1) 5%
Urethane methacrylate 5%
Polymerization initiator: Irgacure 261 (supra) 1%
Sensitizer: Ethyleosin 0.06%
"Matrix precursor"
Polypropylene glycol diglycidyl ether (molecular weight = 380)
47.5%
Pentaerythritol tetrakis (mercaptopropionate) 30.7%
Catalyst: Tris (2,4,6-dimethylaminomethyl) phenol 3.58%
<Preparation of optical recording medium 3>
An optical recording medium 3 of the present invention was obtained in the same manner as the optical recording medium 1 except that the preparation liquid 1 was replaced with the preparation liquid 3 having the following composition.
(Preparation solution 3)
"Optical recording material"
Oxetane compound (OX-7) 5%
Triethylene glycol divinyl ether 5%
Pentaerythritol tetramethacrylate 5%
Polymerization initiator: Irgacure 261 (supra) 1%
Sensitizer: Ethyleosin 0.06%
"Matrix"
Poly (methylphenylsiloxane) [Dow 710 silicone
fluid: Dow Chemical] 81.78%
<Preparation of optical recording medium 4>
An optical recording medium 4 of Comparative Example was obtained in the same manner as the optical recording medium 1 except that the preparation liquid 4 having the following composition was used instead of the preparation liquid 1.
(Preparation solution 4)
"Optical recording material"
Oxetane compound (OX-5) 10%
Epoxy compound (EP-1) 5%
Polymerization initiator: Irgacure 261 (supra) 1%
Sensitizer; ethyl eosin 0.06%
"Matrix precursor"
Polypropylene glycol diglycidyl ether (molecular weight = 380)
47.5%
Pentaerythritol tetrakis (mercaptopropionate) 30.7%
Catalyst: Tris (2,4,6-dimethylaminomethyl) phenol 3.58%
<Preparation of optical recording medium 5>
An optical recording medium 5 of Comparative Example was obtained in the same manner as the optical recording medium 4 except that the preparation liquid 5 having the following composition was used in place of the preparation liquid 4.
(Preparation solution 5)
"Optical recording material"
Pentaerythritol tetramethacrylate 15%
Polymerization initiator: Irgacure 261 (supra) 1%
Sensitizer; ethyl eosin 0.06%
"Matrix precursor"
Polypropylene glycol diglycidyl ether (molecular weight = 380)
47.5%
Pentaerythritol tetrakis (mercaptopropionate) 30.7%
Catalyst: Tris (2,4,6-dimethylaminomethyl) phenol 3.58%
<Preparation of optical recording medium 6>
An optical recording medium 6 of Comparative Example was obtained in the same manner as the optical recording medium 4 except that the preparation liquid 6 having the following composition was used instead of the preparation liquid 4.
(Preparation solution 6)
"Optical recording material"
Oxetane compound (OX-5) 5%
Epoxy compound (EP-1) 5%
Urethane methacrylate 5%
Polymerization initiator: Diphenyliodonium hexafluorophosphate 1%
Sensitizer; ethyl eosin 0.06%
"Matrix precursor"
Polypropylene glycol diglycidyl ether (molecular weight = 380)
47.5%
Pentaerythritol tetrakis (mercaptopropionate) 30.7%
Catalyst: Tris (2,4,6-dimethylaminomethyl) phenol 3.58%
A series of multiple holograms are written in accordance with the procedure described in US Pat. No. 5,719,691 using each of the produced optical recording media, and sensitivity (recording energy), shrinkage resistance, and refractive index contrast are adjusted according to the following method. Measurement and evaluation.

  The obtained results are summarized in Table 1.

"sensitivity"
A digital pattern is displayed on the hologram image forming apparatus shown in FIG. 1 equipped with an Nd: YAG laser (532 nm) on each optical image recording material of the produced hologram, and this digital is generated with an energy of 0.5 to ²⁰ mJ / cm ^2. The patterned hologram was exposed to obtain a hologram. 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.

<Shrink resistance>
The shrinkage resistance was expressed as a shrinkage rate measured by the following method.

  FIG. 2 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.

  If the shrinkage rate of the hologram at the point P (I, J) is M (I, J), the shrinkage rate 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)
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 obtained from the diffraction efficiency of the obtained hologram.

  As is apparent from Table 1, the optical recording medium of the present invention containing an iron arene complex compound as a polymerization initiator and a compound having a group capable of cationic polymerization and a compound having a group capable of radical polymerization as a polymerizable substance. The optical recording medium of the comparative example was excellent in sensitivity, low in shrinkability, and excellent in refractive index contrast.

It is the schematic which shows the basic composition of the holography system used by this invention. 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 Spectroscope 6 Personal computer 7 Moving pinhole plate 8 Pinhole 9 Illumination light 10 Holography system 11 Reproduction light 12 Modulator 14 Optical image recording material 16 Sensor 20 Signal beam 22 Reference beam 30, 32, 34 Lens

Claims (8)

An iron arene complex compound represented by the following general formula (A) as a polymerization initiator contains both a compound having a group capable of cationic polymerization and a compound having a group capable of radical polymerization as a polymerizable substance. Optical recording medium.
Formula (A) [A-Fe- B] + · X -
[Wherein, A represents a cyclopentadienyl group or an alkyl-substituted cyclopentadienyl group, B represents an arene, and X ⁻ represents an anion. ] 2. The optical recording medium according to claim 1, wherein the compound having a group capable of cationic polymerization is a compound having 1 to 4 oxetane rings. Cationic epoxy polymerization, cationic vinyl ether polymerization, cationic alkenyl ether polymerization, cationic allene ether polymerization, cationic ketene acetal polymerization, epoxy-amine step polymerization, epoxy-mercaptan step polymerization, unsaturated ester-amine step polymerization, unsaturated ester-mercaptan step polymerization 3. The optical recording medium according to claim 1, wherein the matrix is formed by at least one polymerization reaction selected from vinyl-silicon hydride step polymerization, isocyanate-hydroxyl step polymerization, and isocyanate-amine step polymerization. 4. The optical recording medium according to claim 3, wherein the matrix is formed by curing an inorganic or organic matrix precursor. 5. The optical recording medium according to claim 4, wherein the matrix precursor is derived from a compound represented by the following general formula (P).
Formula (P) R _n M (OR ′) _4-n
[In the formula, M represents a metal element having a valence of 3 or more, R represents an alkyl group or an allyl group, R ′ represents a lower alkyl group having 4 or less carbon atoms, and n represents an integer of 1 or 2. Represents. ] 6. The optical recording medium according to claim 5, wherein M in the general formula (P) is a metal element selected from silicon, titanium, germanium, zirconium, vanadium and aluminum. 7. A recording method for an optical recording medium, wherein holographic recording is performed by irradiating the optical recording medium according to any one of claims 1 to 6 with an actinic ray. A method for producing an optical recording medium according to any one of claims 1 to 6, comprising a step of mixing a matrix-forming substance and a step of curing the matrix precursor to form a matrix. A method for manufacturing an optical recording medium.

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