JP4821068B2 - Photosensitive composition for volume hologram recording and photosensitive medium for volume hologram recording - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a novel photosensitive composition capable of recording a volume hologram, a volume hologram recording medium using the same, and a volume hologram produced using the recording medium.
[0002]
[Prior art]
The DuPont Omnidex series is the only commercially available photosensitive composition for producing volume holograms at the mass production level. This material mainly contains a radical polymerization monomer and a binder polymer, a photo radical polymerization initiator, and a sensitizing dye, but utilizes a difference in refractive index between the radical polymerization monomer and the binder polymer. That is, when the photosensitive composition formed into a film is subjected to interference exposure, radical polymerization is started in a portion where light is strong, and accordingly, a concentration gradient of the radical polymerization monomer is generated, and radicals are generated from a portion where light is weak to a portion where light is strong. The diffusion transfer of the polymerization monomer occurs. As a result, the density of the radical polymerization monomer can be increased or decreased according to the intensity of the interference light, which appears as a difference in refractive index. Although this material system has the best performance as a photopolymer for volume holograms currently reported, problems have been pointed out in heat resistance and transparency.
[0003]
A material system using both radical polymerization and cationic polymerization has been reported. For example, Japanese Patent No. 2873126 discloses a system using a monomer having a diallyl fluorene skeleton as a high refractive index radical polymerizable monomer and a cationic polymerizable monomer having a refractive index smaller than that of the radical polymerizable monomer. In this system, a high refractive index component is polymerized by radical polymerization at the time of hologram exposure, and then an image is fixed by cationic polymerization at fixing exposure.
[0004]
Moreover, a material system using cationic polymerization is disclosed in, for example, USP 5759721. This material system has an advantage that there is no oxygen inhibition in the radical polymerization system, but there is a problem that the sensitivity of the cationic polymerization is poor and it is difficult to provide sensitivity in a long wavelength region.
[0005]
Japanese Patent No. 2953200 discloses a material system in which an inorganic substance network and a photopolymerizable monomer are used in combination. When an inorganic material that can form a network is used as a binder, this material has the advantages of being excellent in heat resistance, environmental resistance and mechanical strength, and having a large difference in refractive index from a photopolymerizable organic monomer. The hologram recording film formed by the system is rather fragile, and it is inferior in flexibility, processability and coating suitability, and the compatibility between the inorganic binder and the organic monomer is not good, so a uniform coating material is prepared. There is a problem that it is difficult to do.
[0006]
In addition, in Japanese translations of PCT publication No. 2000-508783, a material in which ultrafine metal particles are dispersed in a solid matrix is disclosed as a hologram recording material. However, the matrix needs to have fluidity and has a problem of poor solidity. .
[0007]
Further, as publicly known examples using a combination of a high refractive index aromatic ring-containing binder polymer and a low refractive index fluorine-containing monomer, there are JP-A-5-210343, JP-A-5-210344, and JP-A-5-257416. However, in this combination, since the polymerization reactivity is not sufficient, the sensitivity at the time of interference exposure is not so high. Although the addition of a polyfunctional acrylate to increase the polymerizability of the fluorine-containing monomer is also described, this method impairs the low refractive index inherent in the fluorine-containing monomer. Furthermore, in this combination, there is a problem that the strongly exposed portion where the polymer of the fluorine-containing monomer is present in a high ratio is mechanically fragile, and yellowing easily occurs due to the use of the aromatic ring-containing binder polymer. is there.
[0008]
JP-A-6-67588 discloses a known example in which a low refractive index binder polymer comprising a fluorine-containing acrylic monomer and an acrylic monomer containing no fluorine and a high refractive index aromatic ring-containing monomer are used in combination. However, even in this example, the low refractive index property of the fluorine-containing acrylic monomer is impaired by copolymerization with an acrylic monomer that does not contain fluorine, and further, yellowing is likely to occur due to the aromatic ring of the aromatic ring-containing monomer. There is.
[0009]
[Problems to be solved by the invention]
As an index indicating the performance of the volume hologram, there is a refractive index modulation amount (Δn). This value is calculated by Kogelnik's coupled wave theory. As described above, various volume hologram recording materials are known, but the refractive index modulation amount (Δn) showing the hologram performance is about 0.06 at the maximum, and is applied to a new optical element or the like. At the same time, further improvement of Δn is desired.
[0010]
Also, considering the application to a wide range of fields such as optical elements, not only hologram recording performance such as refractive index difference, sensitivity, transparency, but also various performances including physical properties such as film strength and heat resistance. There is a need for a fully satisfactory material system.
[0011]
The present invention has been accomplished in consideration of the above-mentioned actual situation, and a first object thereof is a volume hologram recording material, a volume hologram recording medium, and a volume hologram having a refractive index modulation amount (Δn) larger than that of the conventional one. It is to obtain a hologram.
[0012]
The second object of the present invention is not only hologram recording performance such as refractive index difference, sensitivity and transparency, but also volume hologram recording material and volume type excellent in physical properties such as film strength and heat resistance. It is to obtain a hologram recording medium and a volume hologram.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a volume hologram recording photosensitive composition provided by the present invention comprises a binder polymer having an alicyclic structure, a fluorine-containing polymerizable compound having two or more photopolymerizable groups, and It contains a photopolymerization initiator, and the binder polymer and the fluorine-containing polymerizable compound have a functional group that can be covalently bonded to each other.
[0014]
The photosensitive medium for volume hologram recording provided by the present invention is characterized in that a film of the photosensitive composition for volume hologram recording is provided on a substrate.
[0015]
The binder polymer having an alicyclic structure generally has a high refractive index, and the polymer of one fluorine-containing polymerizable compound generally has a very low refractive index. Therefore, when the photosensitive composition for hologram recording combined with both is subjected to interference exposure, a large difference in refractive index can be obtained. In the present invention, since a fluorine-containing polymerizable compound having two or more photopolymerizable groups in one molecule is used, the reactivity during interference exposure is good. Therefore, a photosensitive composition for volume hologram recording and a photosensitive medium for volume hologram recording with high sensitivity and a large refractive index modulation amount can be obtained.
[0016]
A polymer having an alicyclic structure as a binder polymer is excellent in transparency because it hardly causes deterioration due to light or heat, for example, yellowing.
[0017]
Furthermore, in the present invention, since a covalent bond can be formed between the alicyclic binder polymer and the fluorine-containing polymerizable compound as the refractive index modulation component, the film strength and heat resistance of the hologram layer can be improved.
[0018]
As the fluorine-containing polymerizable compound, 1,4-bis (2 ′, 3′-epoxypropyl) perfluoro-n-butane as a fluorine-containing monomer is preferably used. Since this compound is excellent in compatibility with the binder polymer and can be blended in a high proportion in the photosensitive composition for volume hologram recording, a hologram recording material having a particularly large refractive index modulation effect can be obtained.
[0019]
Furthermore, when the functional group of the alicyclic binder polymer can be photopolymerized with the photopolymerizable group of the fluorine-containing polymerizable compound at the time of interference exposure, the fluorine-containing polymerizable compound also polymerizes with the binder polymer and reacts in the strongly exposed area. Therefore, the refractive index modulation amount and sensitivity can be further improved.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The photosensitive composition for volume hologram recording provided by the present invention contains a binder polymer having an alicyclic structure, a fluorine-containing polymerizable compound having two or more photopolymerizable groups, and a photopolymerization initiator, The binder polymer and the fluorine-containing polymerizable compound have a functional group capable of being covalently bonded to each other.
[0021]
Δn calculated from Kogelnik's theory indicates the difference in refractive index in the refractive index distribution formed according to the interference light incident on the light-sensitive material. The larger this Δn, the better the hologram. In the present invention, a binder polymer having an alicyclic structure and a fluorine-containing polymerizable compound as a refractive index modulation component are used in combination, but the binder polymer having an alicyclic structure generally has a large refractive index, Polymers of these fluorine-containing polymerizable compounds generally have a very low refractive index.
[0022]
Therefore, when the photosensitive composition for hologram recording combined with both is subjected to interference exposure, the weakly exposed portion is rich in the alicyclic binder polymer and the refractive index is increased, and the strongly exposed portion is exposed to the fluorine-containing polymerizable compound or a polymer thereof. The rich refractive index becomes very small, and the refractive index difference can be increased.
[0023]
In the present invention, a polymer having a part of an alicyclic structure and a functional group capable of reacting with a functional group of a fluorine-containing polymerizable compound to form a covalent bond is used as the binder polymer.
[0024]
The binder polymer used in the present invention has an alicyclic structure portion. A binder polymer having an aromatic ring structure is conventionally known as a high-refractive index binder polymer for hologram recording materials. However, a binder polymer having an aromatic ring structure is easily yellowed by light or heat and has insufficient transparency. . On the other hand, polymers having an alicyclic structure in the molecule generally have a large refractive index. For example, a polymer having a refractive index of 1.55 or more can be used, and it is difficult to cause yellowing and is transparent. Since it is excellent, it is suitable as a high refractive index type binder polymer.
[0025]
Examples of the alicyclic structure of the binder polymer include a cycloalkyl group such as cyclohexyl and a cycloalkylene group such as cyclohexylene. These alicyclic structures can provide a high refractive index when present in any part of the molecule, for example, as a cycloalkylene group in the main chain linkage, and a cycloalkyl group or cycloalkylene group in the side chain. Alternatively, it may be introduced as a cycloalkyl group pendant on the main chain.
[0026]
The binder polymer used in the present invention has a functional group that can react with a functional group of the fluorine-containing polymerizable compound to form a covalent bond. In the present invention, the polymer of the fluorine-containing polymerizable compound used as the refractive index modulation component is mechanically fragile, which causes the film strength and heat resistance of the hologram layer to be impaired. On the other hand, after performing interference exposure using a combination of a binder polymer that can form a covalent bond with the fluorine-containing polymerizable compound and the fluorine-containing polymerizable compound as a refractive index modulation component, unreacted fluorine-containing compounds By covalently bonding a polymerizable compound or a polymer of a fluorine-containing polymerizable compound to a binder polymer by a predetermined reaction mode, a stable bond is generated between the fluorine-containing polymerizable compound and the binder polymer, thereby improving film strength and heat resistance. An excellent hologram layer can be obtained.
[0027]
A functional group copolymerizable with the photopolymerizable group of the fluorine-containing polymerizable compound can be introduced into the binder polymer. In addition, a functional group for covalently bonding the binder polymer to the fluorine-containing polymerizable compound is introduced separately from the photopolymerizable group for interference exposure, and the binder polymer is photopolymerizable to the fluorine-containing polymerizable compound. In addition to the group, a functional group that can be covalently bonded to the introduced functional group may be introduced. In that case, a combination of the functional group of the binder polymer and the functional group of the fluorine-containing polymerizable compound is arbitrarily selected. be able to.
[0028]
The binder polymer satisfying such requirements depends on the covalent bond of hydroxyl group, epoxy group, carboxyl group, acryloyl group, methacryloyl group, etc. Examples of the introduced cyclohexyl resin (for example, EHPE-3150 (manufactured by Daicel Chemical Industries) and ST-1000 (manufactured by Tohto Kasei)), alicyclic imide resins, and the like can be given.
[0029]
It is preferable to introduce into the binder polymer a functional group capable of being photopolymerized or thermally polymerized with the photopolymerizable group of the fluorine-containing polymerizable compound as the covalent bond functional group. The photopolymer type hologram recording material layer is often subjected to uniform exposure or heating over the entire surface after the interference exposure process in order to promote refractive index modulation or complete the polymerization reaction. When the functional group of the binder polymer can be photopolymerized or thermally polymerized with the photopolymerizable group of the fluorine-containing polymerizable compound, the binder polymer and the fluorine-containing polymerizable compound are subjected to post-treatment such as uniform exposure over the entire surface. The covalent bond of can also be completed.
[0030]
Particularly preferably, the binder polymer is introduced with a photopolymerizable group of the fluorine-containing polymerizable compound and a photopolymerizable functional group. For example, when the fluorine-containing polymerizable compound has an ethylenically unsaturated double bond capable of addition polymerization as a photopolymerizable group, the binder polymer is similarly ethylenically unsaturated such as an acryloyl group or a methacryloyl group. Those having a double bond are used. When the fluorine-containing polymerizable compound has a cationic photopolymerizable group such as an epoxy group, a binder polymer having a functional group polymerizable with the cationic photopolymerizable group at the time of interference exposure is used. The functional group capable of polymerizing with the cationic photopolymerizable group at the time of interference exposure includes, for example, a functional group such as a hydroxyl group and a carboxyl group in addition to the cationic photopolymerizable group itself such as an epoxy group and a vinyl ether group.
[0031]
In the case of the particularly preferable combination described above, the fluorine-containing polymerizable compound is not only polymerized with the other adjacent fluorine-containing polymerizable compound in the strongly exposed portion when the hologram recording material layer is subjected to interference exposure, but also the surrounding binder polymer. Since both are polymerized, the reactivity is increased and the sensitivity and refractive index difference of interference exposure are improved. Also in this case, after the interference exposure, the entire surface is uniformly exposed or heated to promote refractive index modulation or complete the polymerization reaction to form a hologram, and the binder polymer and the fluorine-containing polymerizable compound. The covalent bond is further advanced to bring excellent film strength and heat resistance to the hologram recording material layer.
[0032]
In the present invention, other resins may be mixed and used as an auxiliary binder polymer, if necessary, together with the essential binder polymer satisfying the above requirements.
[0033]
As a process of promoting refractive index modulation caused by interference exposure or stabilizing a recorded hologram, there is a process of moving a polymerizable component by heating, etc. For this purpose, these matrix polymers are not completely cured before being cured. Preferably, the glass transition temperature should be relatively low and facilitate the monomer movement. Specifically, the glass transition temperature is preferably 180 ° C. or lower.
[0034]
In the present invention, the component (refractive index modulation component) for modulating the refractive index in the strong exposure part of interference exposure to form interference fringes (refractive index modulation component) has two or more photopolymerizable groups, and the alicyclic type. A fluorine-containing polymerizable compound having a functional group capable of reacting with a functional group of the binder polymer to form a covalent bond is used.
[0035]
A fluorine-containing polymerizable compound has a fluorine atom in its molecular structure and generally has a very low refractive index, and is therefore suitable as a low refractive index type refractive index modulation component. In addition, since the fluorine-containing polymerizable compound used in the present invention has two or more photopolymerizable groups, the polymerization reactivity at the time of interference exposure is large, and excellent sensitivity and refractive index modulation action can be obtained. Therefore, a large refractive index difference can be obtained by using a combination of a fluorine-containing polymerizable compound having two or more photopolymerizable groups and a binder polymer having an alicyclic structure.
[0036]
The fluorine-containing polymerizable compound used in the present invention has a functional group that can react with a functional group of the binder polymer to form a covalent bond. As described above, a binder polymer that can be covalently bonded to each other and a fluorine-containing polymerizable compound are used in combination, and after performing interference exposure, an unreacted fluorine-containing polymerizable compound or a polymer of the fluorine-containing polymerizable compound is predetermined. By covalently bonding to the binder polymer according to the reaction mode, a stable bond is generated between the fluorine-containing polymerizable compound and the binder polymer, and a hologram layer having excellent film strength and heat resistance can be obtained.
[0037]
Further, when the photopolymerizable group of the fluorine-containing polymerizable compound also functions as a functional group capable of reacting with the functional group of the binder polymer to form a covalent bond, as described above, the strong exposure part of interference exposure is used. , The fluorine-containing polymerizable compound not only polymerizes with other adjacent fluorine-containing polymerizable compounds, but also with the surrounding binder polymer, so that the reactivity is increased and the sensitivity and refractive index difference of interference exposure are improved. The effect is obtained.
[0038]
Examples of the fluorine-containing polymerizable compound having two or more photopolymerizable groups include monomers having an ethylenically unsaturated double bond capable of addition polymerization such as acryloyl group and methacryloyl group, and cationic polymerizable groups such as vinyl ether group and epoxy group. Monomers having can be used.
[0039]
As the fluorine-containing polymerizable compound, an oligomer or polymer of a fluorine-containing monomer can be used, but at the time of interference exposure, the smaller the molecular weight of the refractive index modulation component, the easier it is to move to the strongly exposed area in the hologram recording material layer. In view of this, a fluorine-containing monomer is preferred.
[0040]
A fluorine-containing polymerizable compound having an ethylenically unsaturated double bond capable of addition polymerization causes refractive index modulation by radical polymerization during interference exposure, and also polymerizes with a binder polymer having a similar radical polymerizable group for stable sharing. Bonds can be formed. In addition, the fluorine-containing polymerizable compound having a cationically polymerizable group causes refractive index modulation by photocationic polymerization during interference exposure, and also polymerizes with a binder polymer having an epoxy group, a vinyl ether group, a hydroxyl group, a carboxyl group, or the like, and is stable. Covalent bonds can be formed.
[0041]
Specific examples of the fluorine-containing polymerizable compound include 1,4-bis (2 ′, 3′-epoxypropyl) perfluoro-n-butane (produced by Daikin Industries) as a fluorine-containing monomer. This exemplary compound is excellent in compatibility with the binder polymer, and can be blended in a high proportion in the photosensitive composition for volume hologram recording according to the present invention, so that a hologram recording material having a particularly large refractive index modulation effect can be obtained. can get.
[0042]
The photopolymerization initiator is used for initiating or accelerating the polymerization of the fluorine-containing polymerizable compound by interference exposure, and is appropriately selected from a photoradical polymerization initiator and a photocationic polymerization initiator according to the type of polymerization reaction. Select and use.
[0043]
As radical photopolymerization initiators, 1,3-di (t-butyldioxycarbonyl) benzophenone, 3,3 ′, 4,4′-tetrakis (t-butyldioxycarbonyl) benzophenone, N-phenylglycine, 2, Examples include 4,6-tris (trichloromethyl) -s-triazine, 3-phenyl-5-isoxazolone, 2-mercaptobenzimidazole, and imidazole dimers.
[0044]
Photocationic polymerization initiators include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, aromatic phosphonium salts, mixed ligand metal salts such as (η ⁶ -Benzene) (η ^Five -Cyclopentadienyl) iron (II), silanol-aluminum complex, etc. can be illustrated.
[0045]
The photopolymerization initiator is preferably decomposed after hologram recording from the viewpoint of stabilization of the recorded hologram. For example, organic peroxides are preferred because the initiator is easily decomposed by irradiation with ultraviolet rays.
[0046]
Visible laser light, for example, laser light from an argon ion laser (458 nm, 488 nm, 514.5 nm), a krypton ion laser (647.1 nm), a YAG laser (532 nm), etc. is used for recording the hologram. For the purpose of improving the sensitivity at the laser beam wavelength, a sensitizing dye can be added.
[0047]
Sensitizing dyes include thiopyrylium salt dyes, merocyanine dyes, quinoline dyes, styrylquinoline dyes, ketocoumarin dyes, thioxanthene dyes, xanthene dyes, oxonol dyes, cyanine dyes, rhodamine dyes, pyrylium Examples thereof include salt dyes. Sensitizing dyes having an absorption wavelength in the visible light region, when high transparency like an optical element is required, cause changes such as decomposition by heating or ultraviolet irradiation in the post-process after hologram recording and are colorless. Is preferred.
[0048]
The fluorine-containing polymerizable compound is used in a proportion of 10 to 1000 parts by weight, preferably 10 to 100 parts by weight, based on 100 parts by weight of the binder polymer.
[0049]
A photoinitiator is used in the ratio of 1-10 weight part with respect to 100 weight part of binder polymers, Preferably it is 5-10 weight part.
[0050]
The sensitizing dye is used in an amount of 0.01 to 1 part by weight, preferably 0.01 to 0.5 part by weight, based on 100 parts by weight of the binder polymer.
[0051]
Each material as described above is acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl acetate, 1,4- A coating liquid as a photosensitive composition for volume hologram recording according to the present invention is prepared by dissolving in dioxane, 1,2-dichloroethane, dichloromethane, chloroform, methanol, ethanol, isopropanol, or a mixed solvent thereof. be able to. However, when the fluorine-containing polymerizable compound is liquid at room temperature, the amount of coating solvent used can be reduced, and the coating solvent may not be required at all.
[0052]
The hologram recording material layer is formed by applying the coating solution to an appropriate substrate film by a method such as a spin coater, gravure coater, comma coater, bar coater, and the like, and a volume hologram recording photosensitive medium is formed. can get. The thickness of the volume hologram recording material layer is 1 to 100 μm, preferably 10 to 40 μm.
[0053]
As the base film of the photosensitive medium for volume hologram recording, it has transparency, polyethylene film, polypropylene film, polyethylene fluoride film, polyvinylidene fluoride film, polyvinyl chloride film, polyvinylidene chloride film, Polyethylene films such as ethylene-vinyl alcohol film, polyvinyl alcohol film, polymethyl methacrylate film, polyether sulfone film, polyether ether ketone film, polyamide film, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer film, polyethylene terephthalate film, polyimide A resin such as a film is exemplified, and the film thickness is 2 to 200 μm, preferably 10 to 50 μm.
[0054]
Moreover, when the volume hologram recording material layer after drying has adhesiveness, the film illustrated by the said base film can be laminated as a protective film. In this case, the contact surface of the laminate film with the volume hologram recording material layer may be subjected to a release treatment so that it can be easily peeled off later.
[0055]
The volume hologram recording photosensitive medium thus obtained has a hologram recording material layer provided on a base film, and the hologram recording material layer has a binder polymer having a cycloaliphatic structure and a photopolymerizable group. It contains two or more fluorine-containing polymerizable compounds and a photopolymerization initiator.
[0056]
The volume hologram recording photosensitive medium according to the present invention can be subjected to interference exposure by a conventionally known method to form a volume hologram.
[0057]
For example, a hologram original plate is brought into close contact with the hologram recording material layer of a volume type hologram recording photosensitive medium, and interference exposure is performed from the transparent substrate film side using visible light, or ionizing radiation such as ultraviolet rays or electron beams. By doing so, a volume hologram is formed.
[0058]
Further, in order to promote the refractive index modulation by interference exposure or complete the polymerization reaction, it is possible to appropriately perform a process such as full exposure with ultraviolet rays or heating after the interference exposure.
[0059]
The volume hologram recording mechanism of the photosensitive composition for volume hologram recording in the present invention is considered to be the same as a conventionally-known mechanism. That is, when the photosensitive composition formed into a film is subjected to interference exposure, photopolymerization is started in a portion where light is strong, and accordingly, a concentration gradient of the photopolymerizable compound is formed, and from a portion where light is weak to a portion where light is strong. The diffusion transfer of the photopolymerizable compound occurs. As a result, the photopolymerizable compound can be densely and densely according to the intensity of the interference light, which appears as a difference in refractive index. This refractive index difference becomes interference fringes, and a volume hologram is formed.
[0060]
Thus, the hologram recording material layer of the photosensitive medium for volume hologram recording according to the present invention produces interference fringes by interference exposure to form a hologram layer, and a volume hologram is obtained.
[0061]
Further, as apparent from the above, the hologram recording material layer of the photosensitive medium for volume hologram recording in the present invention has a binder polymer at any point in the hologram forming process, usually in post-treatment after interference exposure. And a fluorine-containing polymerizable compound or a polymer thereof, and more preferably, the same covalent bond is generated not only in the post-processing step but also in the interference exposure.
[0062]
That is, when the volume-type hologram recording photosensitive medium according to the present invention is subjected to interference exposure, the fluorine-containing polymerizable compound is preferentially photopolymerized in the strongly irradiated portion of the hologram recording material layer, and accordingly the fluorine-containing polymerizable compound. Diffusion movement occurs, and interference fringes are generated. When the functional group of the binder polymer is photopolymerizable with the photopolymerizable group of the fluorine-containing polymerizable compound at the time of interference exposure, the photopolymerization reaction between the fluorine-containing polymerizable compounds and the fluorine-containing polymerizable compound in the strongly exposed portion Since the photopolymerization of the binder polymer and the binder polymer occur simultaneously, the reactivity of the fluorine-containing polymerizable compound as the refractive index modulation component is increased, and the sensitivity of interference exposure and the difference in refractive index between the strong and weakly exposed portions are increased.
[0063]
Further, the strongly exposed portion of interference exposure is likely to be mechanically brittle because the fluorine-containing polymerizable compound or polymer thereof is present in a high concentration, but the fluorine-containing polymerizable compound or polymer thereof and the binder polymer are not easily exposed during interference exposure. Covalent bonding by photopolymerization also has an effect of improving the film strength and heat resistance of the strongly exposed portion.
[0064]
Further, after the interference exposure, the binder polymer and the fluorine-containing polymerizable compound or the polymer thereof in the hologram recording material layer are exposed to the entire surface, heated, or other suitable means, and limited to the strong exposure portion or the weak exposure portion. The film strength and heat resistance of the entire hologram recording material layer can be improved by uniformly covalently bonding without being performed. In this case, if the binder polymer and the fluorine-containing polymerizable compound or the polymer thereof can be polymerized by whole surface exposure or heating, the hologram recording material layer is used to promote refractive index modulation or fix the hologram after interference exposure. And a process of copolymerizing a binder polymer and a fluorine-containing polymerizable compound or a polymer thereof in order to improve the film strength and durability of the hologram layer. Since it can be put together into a process, it is preferable.
[0065]
【Example】
Next, this invention is demonstrated based on an Example.
[0066]
Example 1
(1) Preparation of photosensitive composition solution for volume hologram recording
The following components and solvent were mixed to prepare a photosensitive composition solution for volume hologram recording.
<Composition of photosensitive composition solution for volume hologram recording>
Alicyclic epoxy resin (EHPE-3150, manufactured by Daicel Chemical Industries, Ltd.): 100 parts by weight
1,4-bis (2 ′, 3′-epoxypropyl) -perfluoro-n-butane (E-7432, manufactured by Daikin Industries, Ltd.): 60 parts by weight
1-hydroxycyclohexyl phenyl ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals): 2 parts by weight
3-ethyl-5-[(3-ethyl-2 (3H) -benzothiazolylidene) ethylidene] -2-thioxo-4-oxazolidinone (NK-1473, manufactured by Hayashibara Biochemical Laboratories): 0 .02 parts by weight
・ Methanol: 30 parts by weight
・ Methyl ethyl ketone: 30 parts by weight
(2) Production of photosensitive medium for volume hologram recording
The above solution was applied onto a 38 μm polyethylene terephthalate (PET) film (Toray Lumirror T-60) using a bar coater so as to have a dry film thickness of 20 μm, thereby producing a photosensitive medium for volume hologram recording. .
[0067]
Next, the hologram recording material layer side of the photosensitive medium for volume type hologram recording was laminated on a mirror, and 514.5 nm argon ion laser light was incident from the PET side to perform interference exposure to record the volume type hologram.
[0068]
Next, the interference fringes were fixed by heating and ultraviolet polymerization to obtain a volume hologram. As a result of calculation from the spectral evaluation result, the refractive index modulation amount Δn was 0.048.
[0069]
【The invention's effect】
According to the present invention, a polymer having an alicyclic structure can be used as a binder polymer, and a refractive index difference can be increased by using a fluorine-containing polymerizable compound as a refractive index modulation component. A photosensitive composition for volume hologram recording and a volume type which has two or more photopolymerizable groups in one molecule and has good sensitivity and high refractive index modulation amount because of good reactivity during interference exposure. A photosensitive medium for hologram recording is obtained.
[0070]
A polymer having an alicyclic structure as a binder polymer is excellent in transparency because it hardly causes deterioration due to light or heat, for example, yellowing.
[0071]
Therefore, a volume hologram recording material, a volume hologram recording medium, and a volume hologram that are excellent in hologram recording performance such as refractive index modulation amount, sensitivity, and transparency are provided.
[0072]
Furthermore, in the present invention, since a covalent bond can be formed between the alicyclic binder polymer and the fluorine-containing polymerizable compound as the refractive index modulation component, the hologram layer is used in spite of the use of the fluorine-containing polymerizable compound. The film strength and heat resistance can be improved.
[0073]
Therefore, it is possible to provide a volume hologram recording material, a volume hologram recording medium, and a volume hologram that are excellent not only in hologram recording performance such as refractive index difference, sensitivity, and transparency, but also in physical properties, Application to a wide range of fields such as optical elements is expected.
[0074]
Furthermore, when the functional group of the alicyclic binder polymer can be photopolymerized with the photopolymerizable group of the fluorine-containing polymerizable compound at the time of interference exposure, the fluorine-containing polymerizable compound also polymerizes with the binder polymer and reacts in the strongly exposed area. Therefore, the refractive index modulation amount and sensitivity can be further improved.

Claims (9)

Contains a binder polymer having an alicyclic structure, a fluorine-containing polymerizable compound having two or more photopolymerizable groups, and a photopolymerization initiator, and the binder polymer and the fluorine-containing polymerizable compound can be covalently bonded to each other. A photosensitive composition for volume hologram recording, which has a functional group. The photosensitive composition for volume hologram recording according to claim 1, further comprising a sensitizing dye. The fluorine-containing polymerizable compound has an ethylenically unsaturated double bond capable of addition polymerization as a photopolymerizable group, and the photopolymerization initiator is a photoradical polymerization initiator. Or the photosensitive composition for volume type hologram recording of 2. The volume type according to claim 1 or 2, wherein the fluorine-containing polymerizable compound has a cationic polymerizable group as a photopolymerizable group, and the photopolymerization initiator is a photocationic polymerization initiator. Photosensitive composition for hologram recording. 5. The fluorine-containing polymerizable compound having a cationic polymerizable group is 1,4-bis (2 ′, 3′-epoxypropyl) perfluoro-n-butane as a fluorine-containing monomer. 2. The photosensitive composition for volume hologram recording described in 1. 6. The binder polymer according to claim 1, wherein the functional group capable of covalent bonding has a photopolymerizable group of a fluorine-containing polymerizable compound and a functional group capable of photopolymerization or thermal polymerization. A photosensitive composition for volume hologram recording. The binder polymer and the fluorine-containing polymerizable compound both have addition-polymerizable ethylenically unsaturated double bonds, and the photopolymerization initiator is a photoradical polymerization initiator. Item 7. A photosensitive composition for volume hologram recording according to Item 6. The binder polymer has a functional group polymerizable with a cationic polymerizable group, the fluorine-containing polymerizable compound has a cationic polymerizable group, and the photopolymerization initiator is a photocationic polymerization initiator. The photosensitive composition for volume hologram recording according to claim 6. 9. A volume hologram recording photosensitive medium, wherein a film of the volume hologram recording photosensitive composition according to claim 1 is provided on a substrate.