JP4351940B2 - Hologram recording material, hologram recording method, and optical recording medium - Google Patents

Description

  The present invention relates to a hologram recording material and a hologram recording method applicable to a high-density optical recording medium, a three-dimensional display, a holographic optical element, and the like.

  General principles relating to hologram production are described in chapter 2 of several literatures and technical books such as “Holographic Display” (Junpei Uchinai, Sangyo Tosho [Non-Patent Document 1]). According to these, the photosensitive hologram recording material is placed at a position where one of the two light fluxes of the coherent laser light is irradiated onto the recording object and the total reflection light from the recording object can be received. The hologram recording material is directly irradiated with the other coherent light in addition to the reflected light from the object without hitting the object. Reflected light from the object is referred to as object light, and light directly applied to the recording material is referred to as reference light, and interference fringes between the reference light and object light are recorded as image information. Next, when the processed recording material is irradiated with the same light (reproduction illumination light) as the reference light, it is diffracted by the hologram so as to reproduce the wavefront of the reflected light that first reaches the recording material from the object during recording. As a result, an object image substantially the same as the real image of the object can be observed three-dimensionally.

A hologram formed by causing the reference light and the object light to enter the hologram recording material from the same direction is called a transmission hologram. The interference fringes are formed at intervals of about 1000 to 3000 per 1 mm in a form perpendicular or nearly perpendicular to the recording material film surface direction.
On the other hand, holograms formed by being incident on opposite sides of the hologram recording material are generally called reflection holograms. The interference fringes are formed at intervals of about 3000 to 7000 per 1 mm in a shape parallel or nearly parallel to the recording material film surface direction.
The transmission hologram can be created by a known method as disclosed in, for example, JP-A-6-43634 [Patent Document 1]. The reflection hologram can be created by a known method disclosed in, for example, JP-A-2-3082 [Patent Document 2] and JP-A-3-50588 [Patent Document 3].

On the other hand, a hologram whose film thickness is sufficiently thick with respect to the interference fringe interval (usually a thickness of about 5 times the interference fringe interval or about 1 μm or more) is called a volume hologram.
On the other hand, a hologram whose film thickness is about 5 times or less of the interference fringe interval or about 1 μm or less is called a planar type or a surface type.

  Further, a hologram that records interference fringes by absorption of a dye or silver is called an amplitude hologram, and a hologram that is recorded by surface relief or refractive index modulation is called a phase hologram. Amplitude holograms are not preferred in terms of light utilization efficiency because light diffraction efficiency or reflection efficiency is significantly reduced due to light absorption, and phase holograms are usually preferred.

In a volume phase hologram, the phase of light can be modulated without absorbing light by forming many interference fringes with different refractive indexes in the hologram recording material instead of optical absorption.
In particular, reflective volume phase holograms, also called Lippmann holograms, are capable of full color, white reproduction and high resolution with high diffraction efficiency due to wavelength selective reflection by black diffraction, and high resolution full color 3D display. Can be provided.
Recently, taking advantage of the wavelength selective reflection, a hologram optical element represented by a head-up display (HUD) mounted on an automobile, a pickup lens for an optical disk, a head-mounted display, a color filter for liquid crystal, a reflective liquid crystal reflector, and the like. (HOE) has been widely put into practical use.
In addition, for example, practical use or application is being studied for lenses, diffraction gratings, interference filters, optical fiber couplers, facsimile light polarizers, architectural window glass, and the like.

By the way, in the recent trend of advanced information society, networks such as the Internet and high-definition TVs are rapidly spreading. In addition, HDTV (High Definition Television) will soon be broadcast, and there is an increasing demand for a high-density recording medium for easily and inexpensively recording image information of 100 GB or more in consumer use.
Furthermore, in the trend of increasing computer capacity, there is a need for ultra-high-density recording media that can record large volumes of information of about 1 TB or more at high speed and low cost for business use such as computer backup and broadcast backup. It has been.
Under such circumstances, a compact, inexpensive optical recording medium that is replaceable and randomly accessible has attracted more attention than a magnetic tape medium that cannot be randomly accessed and a hard disk that is not replaceable and easily failed. However, an existing two-dimensional optical recording medium such as a DVD-R has a recording capacity of about 25 GB at most even if the recording / reproducing wavelength is shortened on the physical principle, and has a sufficiently large recording capacity to meet future requirements. The situation cannot be expected.

  Therefore, a three-dimensional optical recording medium that performs recording in the film thickness direction has attracted attention as the ultimate ultra-high density recording medium. As a promising method, there are a method using a two-photon absorption material and a method using holography (interference). Therefore, a volume phase hologram recording material has recently attracted attention as a three-dimensional optical recording medium (holographic memory). It became so.

  In a holographic memory using a volume phase hologram recording material, two-dimensional digital information (referred to as signal light) using a spatial light modulation element (SLM) such as DMD or LCD instead of object light reflected from a three-dimensional object. Will be recorded a lot. At the time of recording, multiplex recording such as angle multiplexing, phase multiplexing, wavelength multiplexing, and shift multiplexing is performed, so that the capacity can be increased to 1 TB. In addition, a CCD, CMOS, or the like is usually used for reading, and the parallel transfer and reading thereof can increase the transfer rate up to 1 Gbps.

However, the requirements for hologram recording materials used for holographic memories are more severe than those for three-dimensional displays and HOE applications as described below.
(1) High sensitivity (2) High resolution (3) High hologram diffraction efficiency (4) Recording process is dry and quick (5) Multiple recording is possible (Wide dynamic range)
(6) Shrinkage after recording is small (7) Hologram storage stability is good

  In particular, (1) high sensitivity, (3) high diffraction efficiency, (4) dry processing, (6) low shrinkage after recording, and (7) good storage stability. These are physical properties that are contradictory in chemical terms, and it is extremely difficult to achieve both.

  Here, as a known volume phase hologram recording material, a dichromate gelatin method, a bleached silver halide salt method, a photopolymer method, and the like are known as a write-once method, and a photorefractive method and a photochromic polymer as a rewritable method. Methods are known.

However, in these known volume phase hologram recording materials, particularly in the application to high-sensitivity optical recording media, materials that satisfy all of the required requirements are still desired and improvements are desired.
Specifically, for example, the dichromated gelatin method has the advantages of high diffraction efficiency and low noise characteristics, but has extremely poor storage stability, requires wet processing and has low sensitivity, and is suitable for holographic memory applications. Not suitable.
The bleached silver halide method has the advantage of high sensitivity, but it requires wet processing, is complicated in bleaching processing, has problems of large scattering and poor light resistance, and is used for holographic memory applications. After all it is not generally suitable.
The photorefractive material has the advantage that it can be rewritten, but has a problem that a high electric field needs to be applied at the time of recording, and the recording storability is poor.
Although the photochromic polymer system represented by azobenzene polymer material has the advantage that it can be rewritten, it has a problem that the sensitivity is very low and the storage stability is poor. For example, WO9744365A1 [Patent Document 4] presents a rewritable hologram recording material using refractive index anisotropy and orientation control of an azobenzene polymer (photochromic polymer). Although the yield is low and the system is accompanied by a change in orientation, the sensitivity is extremely low, and there is a problem in that the record storability is poor due to the contradiction of being rewritable, which is far from practical use.

Under such circumstances, the dry-processed photopolymer method disclosed in Patent Documents 1 to 3 described above has a binder, a radical polymerizable monomer, and a photopolymerization initiator as a basic composition, and a binder or We have devised a difference in refractive index by using a compound having an aromatic ring or chlorine or bromine on one of the radically polymerizable monomers, and as a result, in the bright part of the interference fringes formed during hologram exposure The monomer can form a refractive index difference by polymerization while the binder gathers in the dark part. Therefore, it can be said that it is a relatively practical method that can achieve both high diffraction efficiency and dry processing.
However, compared with the bleached silver halide method, the sensitivity is about 1/1000, the heat fixing treatment is required for nearly 2 hours in order to increase the diffraction efficiency, and radical polymerization, so that the polymerization inhibition by oxygen is inhibited. In addition, there is a problem that the diffraction wavelength and angle at the time of reproduction change due to the shrinkage of the recording material after exposure and fixing, the lack of storage stability due to the soft film, etc. Therefore, it cannot withstand use as a holographic memory application.

Here, in general, cationic polymerization, particularly cationic polymerization accompanied by ring opening of an epoxy compound or the like with respect to radical polymerization has little shrinkage after polymerization and is not subjected to polymerization inhibition by oxygen, and gives a rigid film. Therefore, some point out that cationic polymerization is more suitable for holographic memory applications.
For example, in JP-A-5-107999 [Patent Document 5] and JP-A-8-16078 [Patent Document 6], a cationically polymerizable compound (monomer or oligomer) is used instead of a binder, and further a sensitizing dye, radical A hologram recording material in which a polymerization initiator, a cationic polymerization initiator, and a radical polymerizable compound are combined is disclosed.
Further, JP-A-2001-523842 [Patent Document 7], JP-A-11-512847 [Patent Document 8] and the like disclose that a sensitizing dye, a cationic polymerization initiator, a cationic polymerizable compound, and a binder are used without using radical polymerization. A hologram recording material using only is disclosed.
However, although these cation polymerization methods show improvement in shrinkage rate compared to radical polymerization methods, the contradiction is that the sensitivity is lowered, and it is considered that this will be a big problem in terms of transfer speed in practical use. . In addition, the diffraction efficiency is lowered, which is considered to be a problem in terms of S / N ratio and multiple recording.

As described above, since the photopolymer method is a method involving mass transfer, when considering application to a holographic memory, if the storage property is good and the shrinkage is reduced, the sensitivity decreases (cation polymerization method). On the other hand, if the sensitivity is improved, storage stability and shrinkage deteriorate (radical polymerization method). Further, in order to improve the recording density of the holographic memory, multiplex recording exceeding 50 times and preferably exceeding 100 times is essential. However, in the photopolymer method, since polymerization with mass transfer is used for recording. In general, a time lag from the start of exposure to the start of recording of about ²⁰ to 50 mJ / cm ² is observed at the beginning of recording. This phenomenon causes a reduction in sensitivity, and it is necessary to control it to adjust the exposure amount, which is a serious problem in practical use.

Such problems of high sensitivity, good storage stability, low shrinkage, dry processing dilemma, and multiple recording characteristics are unavoidable in terms of physical laws as long as conventional photopolymer systems are used. In addition, it is theoretically difficult to satisfy the requirements for holographic memory using a silver halide method, particularly in terms of dry processing.
Therefore, in order to apply hologram recording materials to holographic memory, such a problem has been drastically solved, and in particular, it is completely new that can achieve both high sensitivity and low shrinkage, good storage, dry processing, and multiple recording characteristics. Development of a recording system has been strongly desired.
"Holographic Display", Junpei Uchiuchi, Industrial Books JP-A-6-43634 JP-A-2-3082 Japanese Patent Laid-Open No. 3-50588 International Publication No. 97 / 44365A1 Pamphlet Japanese Patent Laid-Open No. 5-107999 JP-A-8-16078 Special table 2001-523842 Special table 11-512847

  Therefore, the object of the present invention is to achieve both high sensitivity and high diffraction efficiency, good storability, low shrinkage, dry processing, and multiple recording characteristics applicable to high-density optical recording media, three-dimensional displays, holographic optical elements, and the like. It is to provide a hologram recording material and a hologram recording method that can be performed.

As a result of intensive studies by the inventors, the object of the present invention has been achieved by the following means .
In addition, although this invention has the following (2)-(6) and (19) and these and reference relation, other matters were also described for reference of an understanding of this invention.

(1) A hologram recording method characterized by performing hologram recording by refractive index modulation using a polymerization reaction in combination with either a coloring reaction or a decoloring reaction.
(2) It has at least a sensitizing dye, a polymerization initiator, a polymerizable compound, a dye precursor group, and a binder, and can perform hologram recording by refractive index modulation using the coloring reaction and polymerization reaction described in (1) together. A hologram recording material characterized by the above.
(3) In (2), the absorption spectrum of the coloring dye has λmax that is 10 to 200 nm shorter than the hologram reproduction wavelength, ε is 10,000 or more, and the molar extinction coefficient at the hologram reproduction wavelength is 100. The hologram recording material according to (1) or (2), wherein:
(4) The hologram recording material according to (2) or (3), wherein, in (2), the refractive index at the hologram reproduction wavelength is larger for the polymerizable compound than for the binder.
(5) In (4), the polymerizable compound contains at least one aryl group, aromatic heterocyclic group, chlorine atom, bromine atom, iodine atom, or sulfur atom, and the binder does not contain them. The hologram recording material according to (4), characterized in that it is characterized.
(6) Using the hologram recording material according to any one of (2) to (5), a sensitizing dye excited state generated by absorbing light by irradiation with hologram recording light is changed from a dye precursor group by electron transfer or energy transfer. When a reaction that generates a coloring dye and activates the polymerization initiator to cause polymerization of the polymerizable compound occurs in the hologram recording material, more coloring reaction occurs in a bright interference area where light is stronger and the refractive index is increased. Polymerization occurs mainly due to the movement of the polymerizable compound having a higher refractive index than that of the binder, and polymerization occurs, and the binder having a lower refractive index is mainly driven away by the interference dark part where the light is weaker. The hologram recording method according to (1), wherein the interference fringes are recorded by a refractive index modulation method in which the refractive index of the bright part is high and the refractive index of the interference dark part is low.
(7) It has at least a sensitizing dye, a polymerization initiator, a polymerizable compound, a decolorizable dye, a decoloring agent precursor, and a binder, and has a refractive index by combining the decoloring reaction and the polymerization reaction described in (1). A hologram recording material capable of performing hologram recording by modulation.
(8) In (7), the absorption spectrum of the decolorizable dye has λmax that is 10 to 200 nm shorter than the hologram reproduction wavelength, ε is 10000 or more, and the molar extinction coefficient at the hologram reproduction wavelength The hologram recording material according to (1) or (7), wherein
(9) The hologram recording material according to (1), (7) or (8), wherein the refractive index at the hologram reproduction wavelength is smaller in the polymerizable compound than in the binder.

(10) In (9), the binder contains at least one aryl group, aromatic heterocyclic group, chlorine atom, bromine atom, iodine atom, or sulfur atom, and the polymerizable compound does not contain them. The hologram recording material according to (9).
(11) Using the hologram recording material described in (7), the excited state of the sensitizing dye generated by absorbing light by irradiation with hologram recording light activates the decolorizer precursor by electron transfer or energy transfer. When a reaction that erases the decolorizable dye and activates the polymerization initiator to cause polymerization of the polymerizable compound occurs in the hologram recording material, more decoloring reaction occurs in the bright light interference area. As a result, the polymerizable compound having a lower refractive index and a refractive index lower than that of the binder moves mainly to cause polymerization, and the binder is mainly driven into a dark interference area where light is weaker. The hologram recording method according to (1), wherein the interference fringes are recorded by a refractive index modulation method in which the refractive index of the bright part is low and the refractive index of the interference dark part is high.
(12) In (2) to (5) and (7) to (10), at least one of the polymerizable compounds is a liquid having a boiling point of 100 ° C. or higher, (2) to (5), The hologram recording material according to any one of (7) to (10).
(13) The hologram recording method according to (1), (6), or (11), wherein the polymerization reaction is any one of radical polymerization, cationic polymerization, and anionic polymerization in (1).
(14) When the polymerizable group of the polymerizable compound described in (2) or (7) is radical polymerization, ethylenically unsaturated groups such as acryloyl group, methacryloyl group, styryl group, and vinyl group are used as the polymerizable group. (6), (11) having a group portion, and having a oxirane ring, oxetane ring, vinyl ether group, or N-vinylcarbazole moiety as a polymerizable group when polymerization is cationic polymerization or anionic polymerization. ), (13) The hologram recording method.
(15) In (2) and (7), the polymerization initiator is 1) a ketone polymerization initiator, 2) an organic peroxide polymerization initiator, 3) a bisimidazole polymerization initiator, 4) trihalomethyl substitution Triazine polymerization initiator, 5) Diazonium salt polymerization initiator, 6) Diaryliodonium salt polymerization initiator, 7) Sulfonium salt polymerization initiator, 8) Triphenylalkylborate polymerization initiator, 9) Diaryl Iodonium organic boron complex polymerization initiator, 10) sulfonium organic boron complex polymerization initiator, 11) cationic dye organic boron complex polymerization initiator, 12) anionic dye onium salt complex polymerization initiator, 13) metal arene (2) to (5), (7) to (10), (12) hologram, which is any one of a complex polymerization initiator and 14) a sulfonate ester polymerization initiator Non-recording material.

(16) In (15), the polymerization initiator is a radical polymerization initiator that generates radicals, 1) a ketone polymerization initiator, 2) an organic peroxide polymerization initiator, and 3) a bisimidazole polymerization start. 4) Trihalomethyl-substituted triazine polymerization initiator, 5) Diazonium salt polymerization initiator, 6) Diaryliodonium salt polymerization initiator, 7) Sulfonium salt polymerization initiator, 8) Triphenylalkylborate salt Polymerization initiator, 9) diaryliodonium organic boron complex polymerization initiator, 10) sulfonium organic boron complex polymerization initiator, 11) cationic dye organic boron complex polymerization initiator, 12) anionic dye onium salt complex polymerization The hologram recording material according to (15), wherein the hologram recording material is any one of an initiator and a metal arene complex polymerization initiator.
(17) In (15), the polymerization initiator is a cationic polymerization initiator that generates an acid, 4) a trihalomethyl-substituted triazine-based polymerization initiator, 5) a diazonium salt-based polymerization initiator, and 6) a diaryliodonium salt-based The hologram recording material according to (15), which is any one of a polymerization initiator, 7) a sulfonium salt polymerization initiator, 13) a metal arene complex polymerization initiator, and 14) a sulfonate ester polymerization initiator .
(18) The hologram recording method according to (13), wherein when the polymerization is anionic polymerization in (13), a photobase generator is included.
(19) The hologram recording material according to any one of (2) to (5), (12), and (15) to (17), wherein the dye precursor group includes an acid coloring dye precursor and an acid generator.
(20) The decolorizer precursor is any one of an acid generator, a base generator and a radical generator. (7) to (10), (12), (15) to (17) The hologram recording material as described.
(21) In (20), the decolorizer precursor is an acid generator, and the decolorizable dye is a dissociable arylidene dye dissociator, dissociable oxonol dye dissociator, dissociable azo dye dissociator, dissociable xanthene The hologram recording material according to (20), which is any one of a dye dissociator.
(22) In (2) and (7), the molar extinction coefficient at the hologram recording wavelength of the sensitizing dye is 1 or more and 2000 or less, (2) to (5), (7) to (7) 10), (12), (15) to (17), and (19) to (21).
(23) In (2) and (7), a sensitizing dye is added so that the film thickness of the hologram recording material is 100 μm or more and the light transmittance of the hologram recording wavelength is 10% or more and 99% or less. (2) to (5), (7) to (10), (12), (15) to (17), and (19) to (22).
(24) The hologram recording method according to (1), (6), (11), (13), (14), or (18), wherein the hologram recording wavelength and the reproduction wavelength are the same.

(25) The hologram recording method according to (24), wherein the hologram recording / reproducing wavelength is 532 nm.
(26) The hologram recording method according to (24), wherein the hologram recording / reproducing wavelength is in a range of 405 to 415 nm.
(27) A volume phase hologram recording method comprising performing volume phase hologram recording using the hologram recording material or hologram recording method according to any one of (1) to (26).
(28) The hologram recording material or hologram recording method according to any one of (1) to (27), wherein the hologram recording cannot be rewritten in (1) to (27).
(29) 10 times or more using the hologram recording material described in (2) to (5), (7) to (10), (12), (15) to (17), (19) to (23) (1), (6), (11), (13), (14), (18), (24), and (25).
(30) The hologram recording according to any one of (1) to (29), characterized in that the multiple exposure can be performed with the exposure amount during multiple recording being constant throughout the multiple recording in any one of (1) to (29) Method and hologram recording material capable of such recording.

(31) The hologram recording method according to any one of (1) to (30) and a hologram recording material capable of such processing, wherein a wet treatment after hologram exposure is not performed in (1) to (30) .
(32) (2) to (5), (7) to (10), (12), (15) to (17), (19) to (23), (28), (30), (31) The hologram recording material described is equipped with a light-shielding filter capable of cutting a part of the wavelength range of ultraviolet light, visible light and infrared light other than recording light and reproduction light on the front surface, back surface or both surfaces of the hologram recording material. (2) to (5), (7) to (10), (12), (15) to (17), (19) to (23), (28), (30) The hologram recording material according to (31).
(33) (2) to (5), (7) to (10), (12), (15) to (17), (19) to (23), (28), (30), (31) An optical recording medium using the hologram recording material described.
(34) A recording / reproducing method for an optical recording medium using the hologram recording / reproducing method described in (1) to (32).
(35) (2) to (5), (7) to (10), (12), (15) to (17), (19) to (23), (28), (30) to (33) An optical recording medium, wherein the hologram recording material described above is stored in a light-shielding cartridge at the time of storage.
(36) (2) to (5), (7) to (10), (12), (15) to (17), (19) to (23), (28), (30) to (32) Three-dimensional display holograms using the hologram recording material described above and holograms described in (1), (6), (11), (13), (14), (18), (24), (25) to (31) A method of manufacturing a three-dimensional display hologram using a recording method.
(37) (2) to (5), (7) to (10), (12), (15) to (17), (19) to (23), (28), (30) to (32) Holographic optical element using the hologram recording material described above and holograms described in (1), (6), (11), (13), (14), (18), (24), (25) to (31) A method of manufacturing a holographic optical element using a recording method.

  By using the hologram recording material and recording method in which the coloring reaction or decoloring reaction and polymerization reaction of the present invention are used in combination, a hologram recording material and recording method excellent in sensitivity and multiple recording suitability compared to known hologram recording materials. Can be given.

The hologram recording method and hologram recording material of the present invention will be described in detail below.
The present invention is characterized in that it has at least a sensitizing dye, a polymerization initiator, a polymerizable compound, a dye precursor group, and a binder, and can perform hologram recording by refractive index modulation by using a coloring reaction and a polymerization reaction in combination. And a hologram recording method for performing hologram recording by refractive index modulation using the hologram recording material in combination with a coloring reaction and a polymerization reaction, for the purpose of understanding the present invention. In addition, other matters were also described.

The hologram recording material of the present invention is preferably not subjected to wet processing.
The hologram recording material of the present invention is preferably a system that cannot be rewritten. Here, the non-rewritable method is a method of recording by irreversible reaction, and indicates a method in which once recorded data can be stored without being rewritten even if it is overwritten and recorded. Therefore, it is suitable for storing important data that requires long-term storage. However, of course, it is possible to newly record in an area that has not been recorded yet. In that sense, it is generally called “write-once type” or “write-once type”.

The light used for hologram recording of the present invention is preferably any of ultraviolet light, visible light, and infrared light having a wavelength of 200 to 2000 nm, more preferably ultraviolet light or visible light having a wavelength of 300 to 700 nm, and still more preferably. It is visible light of 400 to 700 nm.
Furthermore, the actinic radiation of the present invention is preferably a coherent laser beam (having the same phase and wavelength). The laser used may be any of a solid laser, a semiconductor laser, a gas laser, and a liquid laser. Preferred laser beams include, for example, a 532 nm YAG laser double wave, a 355 nm YAG laser triple wave, and a wavelength around 405 to 415 nm. GaN laser, 488 or 515 nm Ar ion laser, 632 or 633 nm He—Ne laser, 647 nm Kr ion laser, 694 nm ruby laser, 636, 634, 538, 534, 442 nm He—Cd laser, etc. .
It is also preferable to use a nanosecond or picosecond order pulse laser.
When the hologram recording material of the present invention is used for an optical recording medium, it is preferable to use a 532 nm YAG laser double wave or a GaN laser near 405 to 415 nm.
The wavelength of light used for hologram reproduction is preferably the same or longer than the wavelength of light used for hologram exposure (recording), and more preferably the same.

In the hologram recording material of the present invention, after the hologram exposure, a fixing step may be performed by light, heat, or both.
In particular, when an acid proliferating agent or a base proliferating agent is used in the hologram recording material of the present invention, it is preferable to use heating for fixing in order to make the acid proliferating agent or the base proliferating agent function effectively.
In the case of light fixing, the entire area of the hologram recording material is irradiated with ultraviolet light or visible light (non-interference exposure). Preferably, the light source used includes a visible light laser, an ultraviolet light laser, a carbon arc, a high-pressure mercury lamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, a tungsten lamp, an LED, an organic EL, and the like.
In the case of thermal fixing, the fixing step is preferably performed at 40 ° C to 160 ° C, more preferably 60 ° C to 130 ° C.
When both photofixing and heat fixing are performed, light and heat may be applied simultaneously, or light and heat may be added separately.

  The refractive index modulation amount at the time of interference fringe recording is preferably 0.00001 to 0.5, and more preferably 0.0001 to 0.3. In addition, it is preferable that the refractive index modulation amount is smaller as the film thickness of the hologram recording material is larger, and it is preferable that the refractive index modulation amount is larger as the film thickness of the hologram recording material is thinner.

The (relative) diffraction efficiency η of the hologram recording material is given by the following equation.
η = Idiff / Io (Formula 1)
Here, Io is the intensity of transmitted light that is not diffracted, and Idiff is the intensity of light that is diffracted (transmitted) or reflected (reflected). The diffraction efficiency takes any value from 0 to 100%, preferably 30% or more, more preferably 60% or more, and most preferably 80% or more.

The sensitivity of the hologram recording material is generally expressed by the exposure amount per unit area (mJ / cm ² ), and it can be said that the smaller the value, the higher the sensitivity. However, the exposure amount at which time is taken as sensitivity varies depending on documents and patents. When the exposure amount starts recording (refractive index modulation), the exposure amount gives the maximum diffraction efficiency (refractive index modulation). In some cases, the exposure amount giving a diffraction efficiency that is half of the maximum diffraction efficiency may be the exposure amount at which the gradient of the diffraction efficiency is maximum with respect to the exposure amount E.
Further, from the Kugelnick's theoretical formula, the refractive index modulation amount Δn for giving a certain diffraction efficiency is inversely proportional to the film thickness d. That is, the sensitivity for giving a certain diffraction efficiency varies depending on the film thickness, and the smaller the refractive index modulation amount Δn is, the thicker the film thickness d is. Therefore, unless conditions such as film thickness are matched, the sensitivity cannot be generally compared.
In the present invention, sensitivity is defined as “exposure amount giving half the maximum diffraction efficiency (mJ / cm ² )”. The sensitivity of the hologram recording material of the present invention is preferably 1 J / cm ² or less, more preferably 500 mJ / cm ² or less, and 200 mJ / cm ² or less, for example, when the film thickness is about 10 to 200 μm. More preferably, it is most preferably 100 mJ / cm ² or less.

  When the hologram recording material of the present invention is used as an optical recording medium in a holographic memory, a large amount of two-dimensional digital information (referred to as signal light) is recorded using a spatial light modulation element (SLM) such as DMD or LCD. Is preferred. In order to increase the recording density, it is preferable to use multiplex recording. The multiplex recording method includes multiplex recording such as angle multiplex, phase multiplex, wavelength multiplex, and shift multiplex. It is preferable to use shift multiple recording. Also, CCD and CMOS are preferably used for reading the reproduced two-dimensional data.

  When the hologram recording material of the present invention is used in a holographic memory as an optical recording medium, it is essential to perform multiplex recording in order to improve the capacity (recording density). At that time, it is more preferable to perform multiplex recording 10 times or more, more preferably to perform multiplex recording 50 times or more, and most preferably to perform multiplex recording 100 times or more. Furthermore, it is more preferable from the viewpoints of simplifying the recording system, improving the S / N ratio, etc. that the exposure amount in the multiple recording can be kept constant throughout the multiple recording.

  When the hologram recording material of the present invention is used for an optical recording medium, it is preferable that the hologram recording material during storage is stored in a light shielding cartridge. In addition, a light shielding filter capable of cutting a part of the wavelength range of ultraviolet light, visible light, and infrared light other than the recording light and reproduction light wavelengths may be provided on the front surface, back surface, or both surfaces of the hologram recording material. preferable.

  When the hologram recording material of the present invention is used for an optical recording medium, the optical recording medium may be disk-shaped, card-shaped, tape-shaped, or any shape.

  Hereinafter, each hologram recording method of the present invention and each component of the hologram recording material capable of such a recording method will be described in detail.

  The hologram recording method of the present invention is a hologram recording method characterized in that hologram recording by refractive index modulation is performed by using either a coloring reaction or a decoloring reaction in combination with a polymerization reaction.

  In the case of performing hologram recording by refractive index modulation using both a coloring reaction and a polymerization reaction, it is preferable to have at least a sensitizing dye, a polymerization initiator, a polymerizable compound, a dye precursor group, and a binder.

  In the hologram recording method of the present invention in which hologram recording by refractive index modulation is performed using both a coloring reaction and a polymerization reaction, the sensitizing dye excited state generated by absorbing light by irradiation of hologram recording light is caused by electron transfer or energy transfer. When a reaction for generating a coloring dye from the dye precursor group and activating the polymerization initiator to cause polymerization of the polymerizable compound occurs in the hologram recording material, more coloring reaction occurs in the bright interference light portion. Occurs when the refractive index increases and the polymerizable compound having a higher refractive index than that of the binder moves mainly to cause polymerization, and the binder having a lower refractive index is mainly driven away by the dark interference part where light is weaker. A hologram that records interference fringes by a refractive index modulation method in which the refractive index of the interference bright portion is high and the refractive index of the interference dark portion is low at the reproduction wavelength Lamb is a recording method.

At that time, it is important that the refractive index is different between the interference bright part and the interference dark part. In the hologram recording material of the present invention in the case of using the color development reaction and the polymerization reaction, it is preferable that the refractive index is large in the bright interference part. Accordingly, it is preferable that the coloring dye has a higher refractive index at the hologram reproduction wavelength than that of the binder.
In general, the refractive index of a dye takes a high value in the region where the wavelength is longer than that near the absorption maximum wavelength (λmax), and particularly takes a very high value in a region where the wavelength is about 200 nm longer than λmax to λmax. It takes a high value exceeding 2 and even exceeding 2.5.
On the other hand, an organic compound that is not a pigment such as a binder polymer usually has a refractive index of about 1.4 to 1.6.
Therefore, the hologram recording material of the present invention is advantageous in terms of increasing sensitivity because coloring of a dye having a large refractive index is used for refractive index modulation. In order to increase sensitivity, the coloring dye preferably has a λmax that is 10 to 200 nm shorter than the hologram reproduction wavelength in the absorption spectrum, and more preferably has a λmax that is 30 to 130 nm shorter. Ε is 10000 or more, more preferably 20000 or more.
Furthermore, for high diffraction efficiency, the molar extinction coefficient at the hologram reproduction wavelength is preferably 100 or less, more preferably 10 or less, and most preferably 0.

  First, the sensitizing dye of the present invention, which absorbs light by hologram exposure and generates an excited state in the hologram recording material of the present invention that uses both a color development reaction and a polymerization reaction, will be described in detail.

  The sensitizing dye of the present invention preferably generates an excited state by absorbing any of ultraviolet light, visible light, and infrared light having a wavelength of 200 to 2000 nm, more preferably ultraviolet light having a wavelength of 300 to 700 nm. It absorbs light or visible light to generate an excited state, and more preferably absorbs visible light of 400 to 700 nm to generate an excited state.

The sensitizing dye of the present invention is preferably a cyanine dye, squarylium cyanine dye, styryl dye, pyrylium dye, merocyanine dye, arylidene dye, oxonol dye, azurenium dye, coumarin dye, ketocoumarin dye, styrylcoumarin dye, pyran dye, xanthene dye. Thioxanthene dye, phenothiazine dye, phenoxazine dye, phenazine dye, phthalocyanine dye, azaporphyrin dye, porphyrin dye, condensed aromatic dye, perylene dye, azomethine dye, anthraquinone dye, metal complex dye, metallocene dye, etc. And more preferably cyanine dyes, squarylium cyanine dyes, pyrylium dyes, merocyanine dyes, oxonol dyes, coumarin dyes, ketocoumarin dyes, styryl coumarin dyes. Pyran dyes, xanthene dyes, thioxanthene dyes, condensed aromatic dyes, metal complex dyes, include metallocene dyes, more preferred are cyanine dyes, merocyanine dyes, oxonol dyes, metal complex dyes, metallocene dyes. The metal complex dye is particularly preferably a Ru complex dye, and the metallocene dye is particularly preferably a ferrocene.
In addition, "Dye Handbook" (Shin Okawara et al., Kodansha 1986), "Chemistry of Functional Dye" (Shin Okawara et al. CMC 1981), "Special Functional Materials" (Chemical Icmori Taro Saburo et al. CMC 1986) The dyes and dyes described in 1) can also be used as the sensitizing dye of the present invention. The sensitizing dye of the present invention is not limited to these, and any dye and dye that absorbs visible light can be used. These sensitizers can be selected in accordance with the wavelength of the radiation used as a light source according to the purpose of use, and two or more sensitizing dyes may be used in combination depending on the application.

Here, the hologram recording material of the present invention is preferably used for an optical recording medium, that is, a holographic memory. In the holographic memory, in order to increase the recording density, multiple recording is performed over 50 times, and preferably over 100 times. At that time, the film thickness of the hologram recording material is generally required to be at least 100 μm or more, more preferably 500 μm or more in order to generate severe angle dependency due to severe black conditions. Therefore, it is preferable that the hologram recording light passes through the hologram recording material, preferably 10% to 99%, more preferably 20% to 90%.
Therefore, when a sensitizing dye having a high molar extinction coefficient is used, it is necessary to considerably reduce the amount of the sensitizing dye in order for the recording light to pass through such a thick hologram recording material. This is a problem because it causes a significant decrease. Therefore, as a sensitizing dye for holographic memory, it is preferable in terms of sensitivity and multiple recording characteristics that ε is as low as possible and the amount added can be increased.
The molar extinction coefficient of the sensitizing dye at the hologram exposure wavelength is preferably from 1 to 10,000, more preferably from 1 to 5000, further preferably from 5 to 2000, and more preferably from 10 to 1000. Most preferred.

  Specific examples of the sensitizing dye of the present invention are given below, but the present invention is not limited thereto.

  Other preferred examples of the sensitizing dye of the present invention are described in Japanese Patent Application No. 2003-300059. The sensitizing dye of the present invention is a commercial product, or can be synthesized by a known method.

  The polymerization reaction in the present invention is preferably radical polymerization, cationic polymerization or anionic polymerization, and is preferably radical polymerization or cationic polymerization.

  In the hologram recording material of the present invention using both a color reaction and a polymerization reaction, the polymerization initiator is preferably a ketone, an organic peroxide, a trihalomethyl-substituted triazine, a diazonium salt, a diaryl iodonium salt, or a sulfonium salt. , Borate, diaryliodonium organic boron complex, sulfonium organic boron complex, cationic sensitizing dye organic boron complex, anionic sensitizing dye onium salt complex, metal arene complex, sulfonate ester These radical polymerization initiators (radical generators) and cationic polymerization initiators (acid generators), or those having both functions can be mentioned.

In the hologram recording material of the present invention in which a color development reaction and a polymerization reaction are used in combination, the refractive index at the hologram reproduction wavelength is preferably larger for the polymerizable compound than for the binder.
In that case, it is more preferable that the polymerizable compound contains at least one aryl group, aromatic heterocyclic group, chlorine atom, bromine atom, iodine atom, or sulfur atom, and the binder does not contain them.
Furthermore, at least one of the polymerizable compounds is preferably a liquid having a boiling point of 100 ° C. or higher.

Specific examples of preferred polymerization initiators, polymerizable compounds, and binders include those described in Japanese Patent Application No. 2003-300057.
It is also preferable to use an acid proliferating agent from the viewpoint of increasing sensitivity. Specific examples of preferred acid proliferating agents include those described in Japanese Patent Application No. 2003-182849.

  Further, it is also preferable to use anionic polymerization and an anionic polymerization initiator (base generator). In that case, it is also preferable to use a base proliferating agent from the viewpoint of high sensitivity. In these cases, specific examples of preferable examples include those described in Japanese Patent Application No. 2003-178083.

  At that time, when the polymerization is radical polymerization, the polymerizable compound has an ethylenically unsaturated group such as acryloyl group, methacryloyl group, styryl group, vinyl group as the polymerizable group, preferably acryloyl group or methacryloyl group. When the polymerization is cationic polymerization or anionic polymerization, the polymerizable compound has any of an oxirane ring, an oxetane ring, a vinyl ether group, and an N-vinylcarbazole moiety as a polymerizable group, preferably an oxirane ring or It preferably has an oxetane ring.

  Specific examples of preferred polymerization initiators in the present invention are listed below, but the present invention is not limited thereto.

  Next, the color reaction in the present invention in the hologram recording material of the present invention using both the color reaction and the polymerization reaction will be described.

  In the present invention, the color development reaction means a reaction in which the shape of the absorption spectrum changes in the ultraviolet light, visible light, and infrared light regions of 300 to 2000 nm, and more preferably λmax has a longer wavelength in the absorption spectrum. , Indicates a reaction in which either increase in ε occurs, and more preferably indicates a reaction in which both occur. Further, it is more preferable that the color development reaction occurs in a wavelength region of 330 to 700 nm, and most preferable that it occurs in a wavelength region of 400 to 700 nm. In that case, the molar extinction coefficient in the region is preferably 5000 or more, more preferably 10000 or more, and most preferably 20000 or more.

  Here, the dye precursor group is a compound group capable of generating a coloring dye by electron transfer or energy transfer from a sensitizing dye excited state and recording interference fringes using refractive index modulation.

  As the dye precursor group, the following combinations are preferable. About these, the example described in Japanese Patent Application No. 2003-298936 is mentioned preferably as a specific example.

i) A combination comprising at least an acid color-forming dye precursor as a dye precursor and an acid generator. A combination further containing an acid proliferating agent if necessary.
As the acid generator, diaryl iodonium salts, sulfonium salts and sulfonic acid esters are preferable, and the above-mentioned acid generator (cationic polymerization initiator) can be preferably used.
The color former generated from the acid color-formable dye precursor is preferably a xanthene dye, a fluorane dye or a triphenylmethane dye. Particularly preferred specific examples of the acid coloring dye precursor are listed below, but the present invention is not limited thereto.

ii) A combination including at least a base color-forming dye precursor as a dye precursor, a base generator, and, if necessary, a base proliferating agent.
As the base generator, the aforementioned base generator (anionic polymerization initiator) is preferably mentioned, and as the base color-forming dye precursor, a dissociation azo dye, a dissociation azomethine dye, a dissociation oxonol dye, a dissociation xanthene dye , Dissociated fluorane dyes, and non-dissociated isomers of dissociated triphenylmethane dyes.
Here, the dissociation type dye has an active hydrogen having a pKa in the range of about 2 to 14 such as —OH group, —SH group, —COOH group, —NHSO ₂ R group, —CONHSO ₂ R group, etc. Is a general term for dyes whose absorption becomes longer in wavelength or higher in ε due to dissociation.
Therefore, the dissociative dye can be colored with a base.
Particularly preferred specific examples of the base color-forming dye precursor are listed below, but the present invention is not limited thereto.

iii) an organic compound moiety having a function of cleaving a covalent bond by electron transfer or energy transfer with a sensitizing dye excited state, and an organic compound moiety having a feature that becomes a color former when covalently bonded and released When the compound contains a covalently bonded compound (dissociation type dye releasing agent method). A combination further containing a base if necessary. Particularly preferred specific examples are listed below, but the present invention is not limited thereto.

iV) When a compound that reacts by electron transfer with an excited state of a sensitizing dye to change the absorption form is included. So-called electrochromic compounds can be preferably used.

In the hologram recording method using both the coloring reaction and the polymerization reaction of the present invention, the following combinations are preferred.
1) Acid coloring type dye precursor + acid generator cation polymerizable compound as dye precursor group, acid generator as cation polymerization initiator (common)
2) Acid coloring type dye precursor + acid generator radical polymerizable compound as radical precursor group, radical polymerization initiator 3) Base coloring type dye precursor + base generator anion polymerizable compound, anion polymerization as dye precursor group Base generator as initiator (common)
4) Base color-forming dye precursor + base generator radical polymerizable compound as radical precursor group, radical polymerization initiator 5) Dissociative dye releasing agent as dye precursor group,
Anionic polymerizable compound, base generator as anionic polymerization initiator 6) dissociative dye releasing agent as dye precursor group,
Radical polymerizable compound, radical polymerization initiator

  On the other hand, when performing hologram recording by refractive index modulation using a combination of decoloring reaction and polymerization reaction, at least a sensitizing dye, a polymerization initiator, a polymerizable compound, a decoloring dye, a decoloring agent precursor, and a binder. It is preferable to have.

  The hologram recording method of the present invention, which performs hologram recording by refractive index modulation using a decoloring reaction and a polymerization reaction in combination, is the sensitizing dye excited state generated by absorbing light by irradiation of hologram recording light, the electron transfer or energy transfer When the holographic recording material undergoes a reaction that activates the decolorizer precursor to decolorize the decolorable dye, and activates the polymerization initiator to cause polymerization of the polymerizable compound, the light has a stronger interference. More decolorization reaction occurs in the part, the refractive index decreases, and a polymerizable compound having a refractive index lower than that of the binder moves mainly to cause polymerization, and the binder is mainly driven to the interference dark part where light is weaker. And recording interference fringes by a refractive index modulation method in which the refractive index of the interference bright portion is low and the refractive index of the interference dark portion is high at the hologram reproduction wavelength. It is a recording method.

At that time, it is important that the refractive index is different between the interference bright part and the interference dark part. In the hologram recording material of the present invention in the case of using the decoloring reaction and the polymerization reaction, it is preferable that the refractive index is large in the interference dark part. In the interference dark part, since the decolorizable dye remains without being decolored, it is preferable that the decolorizable dye has a higher refractive index at the hologram reproduction wavelength than the binder.
In general, the refractive index of a dye takes a high value in the region where the wavelength is longer than that near the absorption maximum wavelength (λmax), and particularly takes a very high value in a region where the wavelength is about 200 nm longer than λmax to λmax. It takes a high value exceeding 2 and even exceeding 2.5.
On the other hand, an organic compound that is not a pigment such as a binder polymer usually has a refractive index of about 1.4 to 1.6.
Therefore, the hologram recording material of the present invention is advantageous in terms of increasing the sensitivity because decoloring of a dye having a large refractive index is used for refractive index modulation. For high sensitivity, the decolorizable dye preferably has a λmax that is 10 to 200 nm shorter than the hologram reproduction wavelength, more preferably λmax that is 30 to 130 nm shorter in the absorption spectrum. And ε is 10000 or more, more preferably 20000 or more.
Furthermore, for high diffraction efficiency, the molar extinction coefficient at the hologram reproduction wavelength is preferably 100 or less, more preferably 10 or less, and most preferably 0.

Furthermore, in the hologram recording material of the present invention in the case of using a decoloring reaction and a polymerization reaction, it is preferable that the refractive index at the hologram reproduction wavelength is larger in the binder than in the polymerizable compound.
In that case, it is more preferable that the binder contains at least one aryl group, aromatic heterocyclic group, chlorine atom, bromine atom, iodine atom, or sulfur atom, and the polymerizable compound does not contain them.

  Furthermore, at least one of the polymerizable compounds is preferably a liquid having a boiling point of 100 ° C. or higher.

Specific examples of preferred polymerization initiators, polymerizable compounds, and binders include those described in Japanese Patent Application No. 2003-300057.
It is also preferable to use an acid proliferating agent from the viewpoint of increasing sensitivity. Specific examples of preferred acid proliferating agents include those described in Japanese Patent Application No. 2003-182849.

  Further, it is also preferable to use anionic polymerization and an anionic polymerization initiator (base generator). In that case, it is also preferable to use a base proliferating agent from the viewpoint of high sensitivity. In these cases, specific examples of preferable examples include those described in Japanese Patent Application No. 2003-178083.

  Next, the erasing reaction in the present invention in the hologram recording material of the present invention using both the decoloring reaction and the polymerization reaction will be described.

  In the present invention, the decoloring reaction means a reaction in which either λmax is shortened or ε is decreased in the absorption spectrum in the ultraviolet light, visible light, and infrared light regions of 300 to 2000 nm. More preferably, the reaction is such that both of them occur. Further, it is more preferable that the decoloring reaction occurs in a wavelength region of 330 to 700 nm, and most preferable that it occurs in a wavelength region of 400 to 700 nm. At that time, the molar extinction coefficient before decoloration of the decolorizable dye in the region is preferably 5000 or more, more preferably 10,000 or more, and most preferably 20000 or more.

In the hologram recording material of the present invention using both a decoloring reaction and a polymerization reaction, the decoloring agent of the present invention is preferably any one of radical, acid, base, nucleophile, electrophile, and singlet oxygen, Therefore, the decolorizer precursor is preferably any one of a radical generator, an acid generator, a base generator, a nucleophile generator, an electrophile generator, and a triplet oxygen. The decoloring precursor is more preferably any of a radical generator, an acid generator and a base generator.
When the decolorizer precursor is an acid generator, preferred examples include the above-described cationic polymerization initiators. In the case of a radical generator, preferred examples include the aforementioned radical polymerization initiators. In the case of a base generator, preferred examples include the aforementioned anionic polymerization initiators.

  In the hologram recording material of the present invention that uses a decolorization reaction and a polymerization reaction in combination, the decolorizable dye is preferably a cyanine dye, squarylium cyanine dye, styryl dye, pyrylium dye, merocyanine dye, arylidene dye, oxonol dye, Coumarin dye, pyran dye, xanthene dye, thioxanthene dye, phenothiazine dye, phenoxazine dye, phenazine dye, phthalocyanine dye, azaporphyrin dye, porphyrin dye, condensed aromatic dye, perylene dye, azomethine dye, azo dye, anthraquinone A dye or a metal complex dye, and more preferably a cyanine dye, a styryl dye, a merocyanine dye, an arylidene dye, an oxonol dye, a coumarin dye, a xanthene dye, an azomethine dye, an azo dye, a gold It is one of the complex dye.

In particular, when the decolorizer is an acid, the decolorizable dye is preferably a dissociated arylidene dye, a dissociated oxonol dye, a dissociable xanthene dye, a dissociated form of a dissociable azo dye, More preferred is a dissociated oxonol dye or dissociated azo dye. Here, the dissociation type dye has an active hydrogen having a pKa in the range of about 2 to 14 such as —OH group, —SH group, —COOH group, —NHSO ₂ R group, —CONHSO ₂ R group, etc. Is a general term for dyes whose absorption becomes longer in wavelength or higher in ε due to dissociation. Therefore, if the dissociation type dye is treated with a base in advance to obtain a dissociation type, it is possible to prepare a dye having a long wavelength or a high ε in advance, and it is changed to a non-dissociation type by photoacid generation and is decolored (short wavelength Or low ε).

  In particular, when the decolorizer is a base, if an acid color-developing dye color former such as triphenylmethane dye, xanthene dye, or fluorane dye previously treated with an acid as a color former is used as the decoloring dye, It becomes possible to change to an aprotic adduct by generating a base and decolorize (shorter wavelength or lower ε).

  Specific examples of the decolorizable dye of the present invention are given below, but the present invention is not limited thereto.

  In addition, Preferably, the example described in Japanese Patent Application No. 2004-88790 is mentioned as a specific example of dye decoloring reaction.

In the hologram recording method using both the decoloring reaction and the polymerization reaction of the present invention, the following combinations are preferable.
1) Dissociative dye dissociator + acid generator cationic polymerizable compound, acid generator as a cationic polymerization initiator (common)
2) Dissociation type dye dissociation body + acid generator radical polymerizable compound, radical polymerization initiator 3) Acid coloring dye coloring body + base generator Anion polymerizable compound, base generator as anion polymerization initiator (common)
4) Acid color-forming dye color former + base generator radical polymerizable compound, radical polymerization initiator 5) Radical generator radical polymerizable compound, radical polymerization initiator as decoloring dye + decolorizer precursor (common)

  In addition to the sensitizing dye, the dye precursor group, the polymerization initiator, the polymerizable compound, the binder, the decoloring dye, the decoloring agent precursor, etc. In addition, additives such as an electron donating compound, an electron accepting compound, a chain transfer agent, a crosslinking agent, a heat stabilizer, a plasticizer, and a solvent can be used.

The electron-donating compound has the ability to reduce the radical cation of the sensitizing dye or color former, and the electron-accepting compound has the ability to oxidize the radical anion of the sensitizing dye or color former. It has a function to regenerate the body. Specifically, for example, an example described in Japanese Patent Application No. 2003-298936 can be given as a preferable example.
In particular, the electron donating compound is useful for high sensitivity because it can quickly regenerate the sensitizing dye radical cation after the electron transfer to the dye precursor group. As the electron donating compound, those having an oxidation potential lower than that of the sensitizing dye and the color former are preferable. Preferred specific examples of the electron donating compound are listed below, but the present invention is not limited thereto.

Especially as an electron-donating compound, a phenothiazine type compound (for example, 10-methylphenothiazine, 10- (4′-methoxyphenyl) phenothiazine), a triphenylamine type compound (for example, triphenylamine, tri (4′-methoxyphenyl) amine) , TPD compounds (eg, TPD) are preferred, and phenothiazine compounds are most preferred.
Specific examples of the chain transfer agent, the crosslinking agent, the heat stabilizer, the plasticizer, the solvent, and the like are preferably described in Japanese Patent Application No. 2003-300057.

When the hologram recording material of the present invention is used for holographic optical memory applications, it is more preferable that the hologram recording material does not shrink before and after hologram recording from the viewpoint of improving the S / N ratio during signal reproduction.
Therefore, for example, an expansion agent described in JP-A-2000-86914 is used for the hologram recording material of the present invention, or a shrink-resistant binder described in JP-A-2000-250382, 2000-172154, and JP-A-11-344917 is used. It is also preferable to use it.
In addition, it is also preferable to adjust the interference fringe interval by using a diffusing element described in JP-A-3-46687, 5-204288, JP-A-9-506441 and the like.

In known ordinary photopolymers such as Patent Documents 1 to 3 and 5 to 8, since polymerization with mass transfer is used for recording, in general, from the start of exposure of about ²⁰ to 50 mJ / cm ² to the start of recording at the beginning of recording. The time lag is observed. This phenomenon causes a decrease in sensitivity, and it is necessary to control it to adjust the exposure amount, which is a serious problem in practical use. In particular, when performing multiple recording, since the exposure time is different even if the same signal is recorded, it has been a serious problem in system design. That is, there is a problem that the range in which the refractive index modulation amount increases linearly with respect to the exposure amount is narrow.
On the other hand, since the color development reaction and decoloration reaction of the present invention are reactions that do not involve mass transfer, by using this together with the polymerization reaction, the time lag is eliminated and the recording sensitivity is improved. Since multiple recording can be performed while the refractive index modulation amount increases linearly with respect to the recording amount, it is advantageous in terms of suitability for multiple recording.
This is preferable in terms of increasing the capacity, simplifying the recording system, improving the S / N ratio, and the like.

  As described above, the hologram recording material of the present invention provides a completely new recording system that can solve both the above-mentioned problems, particularly high sensitivity and good storage stability, dry processing, and multiple recording characteristics. In particular, it is preferably used for an optical recording medium (holographic optical memory).

  In addition to the optical recording medium, the hologram recording material of the present invention includes a three-dimensional display hologram, a holographic optical element (HOE, for example, a head-up display (HUD) mounted on an automobile, a pickup lens for an optical disk, a head mount, etc. Displays, color filters for liquid crystals, reflective liquid crystal reflectors, lenses, diffraction gratings, interference filters, optical fiber couplers, optical polarizers for facsimiles, architectural window glass), covers for books, magazines, displays such as POPs, It can be preferably used for credit cards, banknotes, packaging and the like for security purposes for preventing gifts and counterfeiting.

In the following, specific examples of the present invention have been described based on experimental results. Of course, the present invention is not limited to these examples. In addition, Example 2 shall be read as a reference example.

[Example 1]
[Hologram recording method using both coloring reaction and polymerization reaction]

  Under a red light, the sensitizing dye, the dye regeneration donor, the dye precursor group + the polymerization initiator, the polymerizable compound and the binder shown in Table 1 were added in an amount of 2 to 5 times methylene chloride (acetone, acetonitrile or Hologram recording materials 101 to 103 and comparative sample 1 were prepared. % Represents mass%.

  The hologram recording materials 101 to 103 and the comparative sample 1 are applied to a glass substrate with a blade so that the thickness is about 100 μm (overcoated if necessary) to form a photosensitive layer, and then heated at 40 ° C. for 3 minutes. It dried and the solvent was distilled off. Furthermore, the hologram recording material 101-103 and the comparative sample 1 were produced by covering the photosensitive layer with a TAC film.

The hologram recording material was exposed and recorded using a YAG laser double wave (532 nm, output 2 W) as a light source by the two-beam optical system for transmission hologram recording shown in FIG. The angle between the object beam and the reference beam is 30 degrees. The beam has a diameter of 0.6 cm and an intensity of 12 mW / cm ² , and the holographic exposure time varies from 0.1 to 50 seconds (irradiation energy ranges from 0.12 to 600 mJ / cm ² ). Then, a He—Ne laser beam of 632 nm was passed through the center of the exposure region at a black angle, and the ratio of the diffracted light to the transmitted light (relative diffraction efficiency) was measured in real time.
As a result, in Comparative Sample 1 (Comparative 1), a time lag between the start of exposure and recording start of 30 mJ / cm ² was observed, whereas no time lag was observed in the hologram recording materials 101 to 103 of the present invention. The diffraction efficiency increased linearly with the quantity. Further, when the exposure energy when the value of half of the maximum diffraction efficiency was shown in the comparative sample 1 was 1, the exposure energies in 101 to 103 were all small, 0.52, 0.61, and 0.65, and high sensitivity. Thus, it was found that the hologram recording material of the present invention has higher sensitivity than a known photopolymer system.
From the above, it can be seen that the hologram recording material of the present invention using both the coloring reaction and the polymerization reaction of the present invention is superior in sensitivity and multiple recording suitability to known photopolymer systems.

In Examples 101 to 103, the sensitizing dyes were S-1, S-4, S-9, S-10, S-11, S-19, S-23, S-31, S-36, S-39, S-41, S-42, S-45, S-50, S-58, S-67, S-71, S-73, S-76, S-77, S-80, S- Even if it is changed to 82, the acid generator (cum cation or radical polymerization initiator) of the dye precursor group is further changed to I-3, I-4, I-6, I-7, I in Samples 101 to 103. Even if it is changed to -8, I-9, or I-10, or the acid coloring type dye precursor of the dye precursor group is changed to L-1 or L-3 in the samples 101 to 103, the same effect is obtained. Is obtained.
Moreover, even if the radical polymerization initiator is changed to I-1, I-11 to I-20 or the like in Samples 101 and 103, the same effect can be obtained.
Further, even if the electron donor is changed to A-2, A-3, A-4, A-5, A-6, A-10, or A-11 in the sample 102, the same effect can be obtained.
Further, the same effect can be obtained even if the binder is changed to polymethyl methacrylate, poly (methyl methacrylate-butyl methacrylate) copolymer, poly (methyl methacrylate-ethyl acrylate) copolymer, polyvinyl acetate or the like in samples 101 to 103. can get.

[Example 2]
[Hologram recording method using both decolorization reaction and polymerization reaction]

  Under a red lamp, the sensitizing dye, the dye regeneration donor, the decoloring dye, the decoloring agent precursor, the polymerization initiator, the polymerizable compound and the binder shown in Table 2 were added in an amount of 2 to 5 times the amount of methylene chloride ( A part of acetone, acetonitrile, or methanol was used if necessary) to prepare hologram recording materials 201 to 203 and comparative sample 2 (Comparative 2). % Represents mass%.

  The hologram recording materials 201 to 203 and the comparative sample 2 are applied to a glass substrate with a blade so that the thickness is about 100 μm (overcoated if necessary) to form a photosensitive layer, and then heated at 40 ° C. for 3 minutes. It dried and the solvent was distilled off. Furthermore, the hologram recording material 201-203 and the comparative sample 2 were produced by covering the photosensitive layer with a TAC film.

The hologram recording material was exposed and recorded using a YAG laser double wave (532 nm, output 2 W) as a light source by the two-beam optical system for transmission hologram recording shown in FIG. The angle between the object beam and the reference beam is 30 degrees. The beam has a diameter of 0.6 cm and an intensity of 12 mW / cm ² , and the holographic exposure time varies from 0.1 to 50 seconds (irradiation energy ranges from 0.12 to 600 mJ / cm ² ). Then, a He—Ne laser beam of 632 nm was passed through the center of the exposure region at a black angle, and the ratio of the diffracted light to the transmitted light (relative diffraction efficiency) was measured in real time.
As a result, in Comparative Sample 1, a time lag between the start of exposure and recording start of 20 mJ / cm ² was observed, whereas in the hologram recording materials 201 to 203 of the present invention, no time lag was observed and the exposure dose was linear. The diffraction efficiency increased. Further, when the exposure energy when the value of half of the maximum diffraction efficiency is shown in the comparative sample 2 is 1, the exposure energy in 201 to 203 is as small as 0.42, 0.52, 0.60, and high sensitivity. Thus, it was found that the hologram recording material of the present invention has higher sensitivity than a known photopolymer system.
From the above, it can be seen that the hologram recording material of the present invention using both the coloring reaction and the polymerization reaction of the present invention is superior in sensitivity and multiple recording suitability to known photopolymer systems.

In Examples 201 to 203, the sensitizing dyes were S-1, S-4, S-9, S-10, S-11, S-19, S-23, S-31, S-36, Change to S-39, S-41, S-42, S-50, S-58, S-67, S-71, S-73, S-76, S-77, S-80, S-82 Even further, in samples 201 to 203, the decolorizer precursor (sometimes a polymerization initiator) was changed to I-1, I-3, I-4, I-6, I-7, I-8, I. The same effect can be obtained by changing to -9, I-10, I-11, I-12, and I-23.
Further, in samples 201 to 203, the acid-decoloring dyes are G-13, G-14, G-15, G-17, G-18, G-19, G-21, G-22, G-23, G Similar effects can be obtained by changing to -24, G-25, and G-26.
Furthermore, even if the electron donor is changed to A-2, A-3, A-4, A-5, A-6, A-10, or A-11 in the sample 203, the same effect can be obtained.

It is the schematic explaining the two-beam optical system for hologram exposure.

Explanation of symbols

10 YAG laser 12 Laser beam 14 Mirror 20 Beam splitter 22 Beam segment 24 Mirror 26 Spatial filter 40 Beam expander 30 Hologram recording material 28 Sample 32 He-Ne laser beam 34 He-Ne laser 36 Detector 38 Rotating stage

Claims (14)

At least, a sensitizing dye, a polymerization initiator, a polymerizable compound, a dye precursor group, have a binder, the hologram recording material characterized by capable of performing hologram recording by the refractive index modulation in combination with polymerization reaction color development reaction . The absorption spectrum of the coloring dye produced by the coloring reaction has λmax that is 10 to 200 nm shorter than the hologram reproduction wavelength, ε is 10000 or more, and the molar extinction coefficient at the hologram reproduction wavelength is 100 or less. The hologram recording material according to claim 1 . The refractive index in the hologram reproducing wavelength, the hologram recording material according to claim 1 or 2, wherein the larger the polymerizable compound than the binder. The polymerizable compound according to claim 3 , wherein the polymerizable compound contains at least one aryl group, aromatic heterocyclic group, chlorine atom, bromine atom, iodine atom, or sulfur atom, and the binder does not contain them. The hologram recording material according to claim 3 . By using a hologram recording material according to claim 1 to 4, a holographic recording method for hologram recording according to combination with the refractive index modulation color reaction with the polymerization reaction, generated by absorbing light by the hologram recording light irradiation When the sensitizing dye excited state is generated in the hologram recording material, a reaction is caused to generate a coloring dye from the dye precursor group by electron transfer or energy transfer, and to activate the polymerization initiator to cause polymerization of the polymerizable compound. More coloring reaction occurs in the interference bright part where the light is stronger, the refractive index rises, and the polymerizable compound having a higher refractive index than the binder moves mainly to cause polymerization, and the interference dark part where the light is weaker Refractive index modulation in which the refractive index of the bright interference part is high and the refractive index of the dark interference part is low at the hologram reproduction wavelength, mainly due to the low refractive index binder being driven away. By law, features and sulfo program recording method to record the interference fringes. Similar claims 1 to 4, the hologram recording material according to claim 1, at least one polymerizable compound is characterized by a boiling point of 100 ° C. or more liquids. The polymerization reaction is radical polymerization, cationic polymerization, a hologram recording method according to claim 5 Symbol mounting, characterized in that any one of anionic polymerization. The polymerization initiator is 1) a ketone polymerization initiator, 2) an organic peroxide polymerization initiator, 3) a bisimidazole polymerization initiator, 4) a trihalomethyl-substituted triazine polymerization initiator, and 5) a diazonium salt polymerization. Initiator, 6) diaryl iodonium salt polymerization initiator, 7) sulfonium salt polymerization initiator, 8) triphenylalkyl borate polymerization initiator, 9) diaryl iodonium organic boron complex polymerization initiator, 10) sulfonium Organic boron complex polymerization initiators, 11) Cationic dyes Organic boron complex polymerization initiators, 12) Anionic dye onium salt complex polymerization initiators, 13) Metal arene complex polymerization initiators, 14) Sulfonate esters The hologram recording material according to claim 1, wherein the hologram recording material is a polymerization initiator. At claims 1-4, hologram recording material according to any one of claims 1～4,6,8, characterized in that the dye precursor group comprises an acid color-forming dye precursor and an acid generator. The hologram recording material according to any one of claims 1 to 4, 6, and 8 to 9, wherein the hologram recording is a system that cannot be rewritten. The hologram recording method according to claim 5 or 7 , wherein multiplex recording is performed 10 times or more using the hologram recording material according to any one of claims 1 to 4, 6 , and 8 to 10. At 11. The hologram recording method according to claim 11, wherein the can multiplex recording remains even throughout a certain time of multiple recording exposure amount of any of the time of multiple recording. An optical recording medium comprising the hologram recording material according to any one of claims 1 to 4, 6, and 8 to 10. An optical recording medium, wherein the hologram recording material according to any one of claims 1 to 4, 6, and 8 to 10 is stored in a light-shielding cartridge at the time of storage.

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