JP5665165B2 - Composition for volume hologram recording material and volume hologram recording medium - Google Patents

Description

  The present invention relates to a photosensitive composition capable of forming a pattern in which movement of each component in the composition is caused by pattern exposure and the spatial distribution of each component is changed, and a pattern forming method using the composition. . The present invention also relates to a composition for a hologram recording material for a hologram recording layer on which the photosensitive composition records a volume phase hologram, and the hologram recording layer and a volume phase hologram recording medium including the hologram recording layer.

A holographic diffraction grating (hologram) is a light-dark (interference) pattern recorded on a photosensitive material or the like as a pattern of refractive index or absorptivity. Since it has multiple functions, it is a diffractive optical element, holographic optical memory, Many applications have been reported in a wide range of fields, such as photonics and information displays, such as band wavelength filters, photonic crystals, optical waveguide couplers, optical interconnections, stereoscopic image displays, and head-up displays.
In these applications, a high refractive index change and recording sensitivity are usually required. Furthermore, low polymerization shrinkage is required in order to prevent deterioration of reproduction light quality caused by mechanical distortion of the recorded hologram due to polymerization shrinkage accompanying polymerization that occurs during holographic exposure.

As conventional typical hologram recording material compositions, dichromated gelatin photosensitive materials and bleached silver salt photosensitive materials have been used. These have high diffraction efficiency, but have a drawback in that the processing at the time of hologram production is complicated, and in particular, wet development processing is necessary.
As a dry hologram photosensitive material that overcomes these disadvantages, the DuPont Omnidex series is widely known. This material has a radical polymerization monomer, a binder polymer, a photo radical polymerization initiator, and a sensitizing dye as main components, and records a hologram using 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, depending on the intensity of the interference light, the density of the radical polymerization monomer and the density of the polymerized polymer can be made dense, and a hologram is formed as the difference in refractive index between them and the binder polymer. Although this material system has high performance as a currently reported hologram photopolymer, it is limited to a thickness of about 30 μm, and problems are pointed out in heat resistance and transparency.

  In addition, a material system using radical polymerization and cationic polymerization in combination (see Patent Document 1) and a material system using cationic polymerization (see Patent Document 2) have been reported. Since they are not compatible with each other, the hologram recording film formed of this material system has problems such as a decrease in transparency due to phase separation and an increase in scattering loss based thereon. Furthermore, mechanical strength and environmental stability are still insufficient.

  Moreover, the material system which used the inorganic substance network and the photopolymerizable monomer together is disclosed (refer patent document 3). 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 brittle and has problems of poor flexibility, workability, coating suitability, and poor compatibility between the inorganic binder and the organic monomer. There is a problem that it is difficult to adjust.

  A material in which ultrafine metal particles are dispersed in a solid matrix is disclosed as a hologram recording material (see Patent Document 4). However, in the present invention, it is necessary to give the matrix fluidity, not only the solidity is bad, but also the interface adhesion between the metal particle interface and the solid matrix is bad, brittle, and water penetrates into the interface. is there.

  Further, a hologram recording material using an organic-inorganic hybrid polymer and organometallic fine particles having a photopolymerization reactive group is disclosed (see Patent Document 5). However, in the present invention, heating and ultraviolet polymerization are required to fix the interference fringes, and there is a problem as an industrial process.

  As a material for performing hologram recording by a simpler method, a hologram recording material in which inorganic fine particles are dispersed in a photopolymerizable monomer is disclosed (see Patent Document 6, Patent Document 7, and Non-Patent Document 1). However, in the present invention, there is a problem that the light scattering loss is large because the inorganic fine particles used have a large particle size, a wide particle size distribution, and the inorganic fine particles tend to aggregate.

By the way, multiplex recording is indispensable for ultra high density optical recording of volume holograms, and volume shrinkage must be made as small as possible in order to achieve this multiplex recording. That is, if the shrinkage caused by the polymerization is large, the distortion that occurs during the multiple recording of the initially written recording gradually increases with the recording, and eventually the recording cannot be read (error occurs).
Non-Patent Document 2 poses a serious problem that, in a normal photopolymer system, an error occurs during data input / output due to distortion of recording interference fringes due to volume shrinkage during monomer polymerization.
On the other hand, development of compounds with small volume shrinkage accompanying polymerization has been performed. As examples of compounds that suppress volume shrinkage, Non-Patent Documents 3 and 4 disclose polymerizable monomers that expand in volume during polymerization. However, since the compound is a solid at room temperature in the monomer state, it does not make practical sense from the viewpoint of a low volume shrinkable monomer required in various industrial fields.

  As a monomer suitably used for a volume hologram recording medium, a vinylcyclopropane compound is known. For example, Patent Document 8 discloses an example in which vinylcyclopropane is used as a recording monomer for a composition for hologram recording. However, in this example, since a large amount of a urethane matrix was used in the composition, a sufficient recording capacity could not be obtained.

As a volume hologram recording material composition, a composition composed of a polyfunctional monomer is generally known. When the polyfunctional monomer is a radical polymerization system, the volume shrinkage is generally 10%. It is extremely difficult to achieve polymerization shrinkage of less than 5% by itself. This is explained by the difference between the distance between the monomers and the bond distance between the repeating units of the monomer in the polymer compound, and the monomer is less susceptible to the weak attractive force (van der Waals bond) acting between the monomer molecules before the polymerization reaction. This is because they are superposed on each other to form a covalent bond distance. That is, the shrinkage of the volume occurs due to the very short covalent bond distance from the weakly interacting van der Waals bond due to the polymerization reaction.
When this polyfunctional monomer is a cationic polymerization system such as epoxy or oxetane, bond breakage occurs due to ring opening accompanying polymerization, so the shrinkage rate is lower than that of radical polymerization systems, but the polymerization shrinkage is the smallest. However, it is very difficult to achieve 3% or less.
Under such circumstances, rapid development of a holographic recording composition that can achieve both a high recording capacity and a small polymerization shrinkage ratio is desired.

Japanese Patent Laid-Open No. 5-107999 US Pat. No. 5,759,721 JP-A-6-019040 JP 2000-508883 gazette JP 2002-236440 A JP 2003-084551 A Japanese Patent Laying-Open No. 2005-099612 JP 2007-291056 A

Applied Physics Letters (Appl. Phys. Lett.), 2002, Vol. 81, p. 4121-4123 Journal of the Japan Printing Society, 2004, 41, 279 pages Macromolecules, 1994, 27, pp. 5543-5546 Macromolecules, 1996, 29, pp. 1943-1950

  The object of the present invention is to achieve low shrinkage and diffraction by dispersing fine particles in a mixture of an ene compound having an ethylenically unsaturated group and a thiol compound having a mercapto group (hereinafter also referred to as “ene / thiol polymerization compound”). An object of the present invention is to provide a composition for volume hologram recording material in which a highly efficient hologram is permanently formed.

As a result of intensive studies to achieve the above object, the present inventors have found the present invention.
That is, as a first aspect, there is provided a volume hologram recording material composition for recording interference fringes generated by interference of coherent light by a difference in refractive index, and (a) having at least two ethylenically unsaturated groups Ene compound (hereinafter also referred to as “ene compound”), (b) thiol compound having at least two mercapto groups (hereinafter also referred to as “thiol compound”), and (c) fine particles having a particle diameter of 1 nm or more and 100 nm or less A composition for volume hologram recording material comprising:
As a second aspect, the difference between the refractive index of the polymer of the (a) ene compound and the (b) thiol compound and the refractive index of the (c) fine particles is 0.01 or more and 1.3 or less. The composition for a volume hologram recording material according to the first aspect.
As a third aspect, the composition for volume hologram recording material according to the first aspect or the second aspect, wherein the fine particles (c) are inorganic fine particles.
As a fourth aspect, the composition for volume hologram recording material according to the third aspect, wherein (c) the fine particles are silica fine particles.
As a fifth aspect, the composition for volume hologram recording material according to the first aspect or the second aspect, wherein the fine particles (c) are organic fine particles.
As a sixth aspect, the composition for volume hologram recording material according to the fifth aspect, wherein the fine particles (c) are hyperbranched polymers.
As a seventh aspect, the proportion of the (c) fine particles in the total volume of the (a) ene compound, the (b) thiol compound and the (c) fine particles is 3% by volume or more and 50% by volume or less. The composition for a volume hologram recording material according to any one of the first aspect to the sixth aspect.
As an eighth aspect, there is provided a volume hologram recording material composition for recording interference fringes caused by interference of coherent light by a difference in refractive index, and (a) an ene compound having at least two ethylenically unsaturated groups And (b) a thiol compound having at least two mercapto groups, and (d) a branched polymer having a weight average molecular weight (Mw) measured in terms of polystyrene by gel permeation chromatography of 500 to 5000000. Composition.
As a ninth aspect, the difference between the refractive index of the polymer of the (a) ene compound and the (b) thiol compound and the refractive index of the (d) branched polymer is 0.01 or more and 1.3 or less. The composition for volume hologram recording material according to the eighth aspect.
As a tenth aspect, the proportion of the (d) branched polymer in the total volume of the (a) ene compound, the (b) thiol compound and the (d) branched polymer is 3% by volume or more and 50% by volume. The composition for volume hologram recording material according to the eighth aspect or the ninth aspect, which is the following.
As an eleventh aspect, a volume hologram recording layer comprising the composition according to any one of the first aspect to the tenth aspect.
As a twelfth aspect, a volume hologram recording medium including the volume hologram recording layer according to the eleventh aspect.
As a thirteenth aspect, the volume hologram recording medium according to the twelfth aspect, wherein the volume hologram recording layer has a structure arranged between two transparent substrates.
Further, the present invention is a volume hologram recording material composition that records interference fringes caused by interference of coherent light as a particularly preferred embodiment of the first aspect, by using a difference in refractive index, (A) an allyl alcohol derivative having at least two allyl groups, (b) a thiol compound having at least two mercapto groups, and (c) fine particles having a particle size of 1 nm or more and 100 nm or less, by light interference exposure, The present invention relates to a composition for a volume hologram recording material in which fine particles of component (c) move from a bright part to a dark part as polymerization of component (a) and component (b) proceeds to form interference fringes having different refractive indexes.

  According to the present invention, by dispersing the fine particles in the ene / thiol polymerization compound, the various functions of the fine particles and the ease of workability and moldability of the polymer, low shrinkage and high diffraction efficiency. It is possible to provide a composition for a volume hologram recording material in which a hologram is permanently formed, and a volume hologram recording medium.

1 is a ¹ H NMR spectrum diagram of HB-TFA29 obtained in Reference Example 1. FIG. FIG. 2 is a conceptual diagram of two-beam interference exposure for a volume hologram recording medium. FIG. 3 is a graph showing a change in exposure time of the diffraction efficiency of the volume hologram recording medium in the first embodiment. FIG. 4 is a graph showing a change in exposure time of diffraction efficiency of the volume hologram recording medium in Example 3. FIG. 5 is a graph showing a change in exposure time of diffraction efficiency of the volume hologram recording medium in Example 4. FIG. 6 is a graph showing a change in exposure time of diffraction efficiency of the volume hologram recording medium in Example 5. FIG. 7 is a graph showing a change in the exposure time of the diffraction efficiency of the volume hologram recording medium in Reference Example 6. FIG. 8 is a graph showing a change in exposure time of the refractive index modulation amount of the volume hologram recording medium in Reference Example 6. FIG. 9 is a graph showing a change in the exposure time of the diffraction efficiency of the volume hologram recording medium in Reference Example 7. FIG. 10 is a graph showing the exposure time change of the refractive index modulation amount of the volume hologram recording medium in Reference Example 7. FIG. 11 is a graph showing the exposure time change of the diffraction efficiency of the volume hologram recording medium in Reference Example 8. FIG. 12 is a graph showing the exposure time change of the refractive index modulation amount of the volume hologram recording medium in Reference Example 8. FIG. 13 is a graph showing the change in exposure time of the diffraction efficiency of the volume hologram recording medium in Reference Example 9. FIG. 14 is a graph showing a change in exposure time of the refractive index modulation amount of the volume hologram recording medium in Reference Example 9.

Hereinafter, the present invention will be described in detail.
The composition for volume hologram recording material of the present invention comprises (a) an ene compound having at least two ethylenically unsaturated groups, (b) a thiol compound having at least two mercapto groups, and (c) a particle size of 1 nm or more. It consists of fine particles of 100 nm or less.

  Next, a volume hologram recording method for a volume hologram recording medium using the composition for volume hologram recording material will be described. The recording principle is not clear, but it is presumed as follows.

First, when two laser beams are simultaneously irradiated onto the medium, interference fringes are formed on the medium in which bright portions and dark portions are arranged in stripes. Then, in the bright part of the medium, the monomer (a) ene compound and (b) thiol compound start to polymerize, and the monomer concentration in the bright part decreases. Accordingly, a concentration gradient of the monomer is generated in the dark part and the bright part, and the monomers (ene compound and thiol compound) are moved and supplied from the dark part to the bright part, and further polymerization proceeds.
Instead, the fine particles move from the bright part to the dark part. In addition, the distribution of fine particles is biased between the bright part and the dark part. When a certain amount of time has passed, the polymerization of the monomer finally proceeds even in the dark part, and the entire recording layer of the medium becomes a polymer. In this manner, a fine stripe distribution corresponding to the dark portion is formed in the monomer polymer. Since the refractive index of the fine particles is different from that of the monomer polymer, a refractive index distribution is formed in the recording layer, and a hologram is recorded. At the time of reproduction, when the region where the interference fringes are formed is irradiated with reproduction light, diffraction occurs and a hologram image is reproduced.

  Hereinafter, the configuration of the volume hologram recording material composition of the present invention will be described in detail.

[(A) Ene compound having at least two ethylenically unsaturated groups]
The ene compound having at least two ethylenically unsaturated groups in the present invention is not particularly limited as long as it is a polyfunctional compound having two or more ethylenically unsaturated groups in one molecule. It may be a polymer. Here, the ethylenically unsaturated group includes, but is not limited to, a vinyl group, an allyl group, a (meth) acryloyl group, and the like. The (meth) acryloyl group refers to an acryloyl group and a methacryloyl group.
Examples of the ene compound used in the present invention include allyl alcohol derivatives, ester compounds of (meth) acrylic acid and polyhydric alcohol, urethane acrylate, divinylbenzene, and the like. Of these, allyl alcohol derivatives are particularly preferable.

  Specific examples of the allyl alcohol derivatives include triallyl isocyanurate, triallyl cyanurate, diallyl maleate, diallyl adipate, diallyl phthalate, triallyl trimellitate, tetraallyl pyromellitate, glyceryl diallyl ether, trimethylolpropane diallyl Examples include ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, glyoxal bis (diallyl acetal), and the like.

  In the ester compound of (meth) acrylic acid and polyhydric alcohol, specific examples of the polyhydric alcohol that forms the ester compound with (meth) acrylic acid include ethylene glycol, propylene glycol, 1,4-butanediol, , 6-hexanediol, glycerin, trimethylolpropane, pentaerythritol, sorbitol and the like.

  The above-mentioned ene compounds may be used alone or in combination of two or more as necessary.

[(B) Thiol compound having at least two mercapto groups]
The thiol compound having at least two mercapto groups in the present invention is not particularly limited as long as it is a polyfunctional compound having two or more, preferably 2 to 4 mercapto groups in one molecule. It may be aromatic, monomer or polymer.

  The classification of thiol compounds used in the present invention includes polyols and terminal thiol-substituted carboxylic acids (or esters or acyl halogens) including α- or β-mercaptocarboxylic acids such as thioglycolic acid and β-mercaptopropionic acid. And those obtained by esterification with a derivative such as a compound).

  Examples of the compound obtained as described above include ethylene glycol bis (thioglycolate), ethylene glycol dimercaptopropionate, pentaerythritol tetrakis (3-mercaptopropionate), trimethylolpropane tris (thioglycolate). ), Trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (thioglycolate), pentaerythritol tetrakis (3-mercaptopropionate), and the like. Among these, trimethylolpropane triesters or pentaerythritol tetraesters are particularly preferable.

  The said thiol compound may be used independently and may be used in combination of 2 or more type as needed.

  In the composition for volume hologram recording material of the present invention, the amount ratio of the ene compound and the thiol compound is not particularly limited. However, when one is excessively large, factors such as insufficient curing at the time of exposure and a decrease in diffraction efficiency. It becomes. Therefore, the ratio of the number of functional groups, that is, the ratio of the number of ethylenically unsaturated groups to the number of mercapto groups is preferably 1: 5 to 5: 1, and more preferably 1: 2 to 2: 1.

  The composition for volume hologram recording material according to the present invention may contain at least one reactive diluent. Reactive diluents can be used to adjust the viscosity of the composition. Thus, reactive diluents are low viscosity monomers that contain at least one functional group that is capable of polymerizing when exposed to actinic radiation. For example, vinyl reactive diluents and (meth) acrylate monomer diluents may be used.

  The above reactive diluents may be used alone or in combination of two or more as required.

[(C) Fine particles]
The particle diameter of the fine particles is 100 nm or less. This is because if it is too large, light scattering tends to occur. More preferably, it is 50 nm or less. The smaller the particle size, the better. However, the smaller the particle size, the more the viscosity of the composition increases. From the viewpoint of workability and moldability, the particle size is actually limited to 1 nm or more.

Further, since the refractive index in the volume hologram composition is determined by the volume ratio of the constituent components, the achievable refractive index difference increases as the volume ratio of the inorganic fine particles to the volume of the resin component increases.
Therefore, the ratio of (c) fine particles to the total volume of (a) ene compound, (b) thiol compound and (c) fine particles is preferably 3% by volume or more, more preferably 5% by volume or more.
However, there is a limit to the amount of fine particles that can be dispersed in the volume hologram composition, and if it is too large, diffusion becomes difficult, so 50 volume% or less is preferable, and more preferably 40 volume% or less.

  Here, the resin component is, for example, (a) an ene compound and (b) a thiol compound, but when the volume hologram material composition contains an organic compound such as a binder resin or a reactive diluent, It refers not only to a) ene compounds and (b) thiol compounds, but also binder resins and reactive diluents.

  In the composition for a volume hologram recording material of the present invention, the difference between the refractive index of the polymer of the (a) ene compound and the (b) thiol compound and the refractive index of the (c) fine particles is 0.01 or more. 1.3 or less, more preferably 0.03 or more and 1.1 or less. This is because when the difference in refractive index is less than 0.01, the final refractive index modulation amount decreases, so that the recording capacity decreases. On the other hand, when it exceeds 1.3, light scattering may occur. Because.

  The fine particles are not particularly limited as long as they can achieve the object of the present invention, and can be freely selected from organic fine particles and inorganic fine particles.

  Specific examples of the organic fine particles include hyperbranched polymers, dendrimers, starburst polymers, fullerenes, and nanodiamonds. Preferred are polymers having a highly branched main chain, such as dendrimers, starburst polymers, and hyperbranched polymers. Of these, hyperbranched polymers are particularly preferred from the viewpoints of dispersibility, transparency, and economy. Examples of the hyperbranched polymer include the hyperbranched polymer described in US Pat. No. 2,0081,76146.

  Specific examples of the inorganic fine particles include titanium oxide, silicon oxide, zinc oxide, aluminum oxide, antimony oxide, chromium oxide, cerium oxide, yttrium oxide, zirconium oxide, tin oxide, copper oxide, iron oxide, magnesium oxide, and manganese oxide. , Metal oxides such as holmium oxide, bismuth oxide, cobalt oxide, erbium oxide, gadolinium oxide, indium oxide, nickel oxide, strontium oxide, ytterbium oxide, nitrides such as silicon nitride, titanium nitride, zirconium nitride, niobium nitride, carbonization Dielectric fine particles such as carbides such as silicon, titanium carbide, molybdenum carbide, tungsten carbide, IV group semiconductors such as Si and Ge, II-VI group semiconductor fine particles such as CdS, CdSe, ZnSe, CdTe, ZnS, HgS, HgSe, GaAs, In III-V group semiconductor particles such as InSb, IV-VI group semiconductor particles such as PbS and PbSe, metal particles such as gold, silver, copper, nickel, aluminum, iron, cobalt, tungsten, molybdenum and niobium, etc. If it can disperse | distribute uniformly to a functional monomer, it will not specifically limit.

  In order to uniformly disperse the inorganic fine particles, it is preferable to perform a treatment such as chemical modification of the surface at the time of fine particle preparation or addition of a dispersant after the fine particle preparation. As the treatment, any compound and treatment method may be used as long as the dispersibility of the inorganic fine particles is improved. For example, methods such as encapsulation, surface treatment, and hybridization can be mentioned. Modification using a surface treatment agent is preferable because it is industrially simple. The fine particles can be used alone, in a mixture, or in a complex.

[(D) Branched polymer]
In another aspect of the present invention, in the composition for a volume hologram recording material, a branched polymer can be used as the component (d) instead of the fine particles as the component (c).
Here, examples of the branched polymer include a branched polymer having a structural unit represented by the following formula (1) or the following formula (2), and a branched polymerization having a structure represented by the following formula (3). Things.

The branched polymer has a weight average molecular weight (Mw) of 500 to 5000000 measured in terms of polystyrene by gel permeation chromatography. Preferably 1000 to 1
000000, more preferably 2000 to 500000.

  In the above formula (3), n is the number of repeating unit structures and represents an integer of 2 or more.

Further, as in the above component (c), the proportion of (d) branched polymer in the total volume of (a) ene compound, (b) thiol compound and (d) branched polymer is preferably 3% by volume or more. More preferably, it is 5% by volume or more.
However, there is a limit to the amount of the branched polymer that can be dispersed in the volume hologram composition, and if it is too much, it becomes difficult to diffuse. Therefore, it is preferably 50% by volume or less, more preferably 40% by volume or less.

  Furthermore, the difference between the refractive index of the polymer of the (a) ene compound and the (b) thiol compound and the refractive index of the (d) branched polymer is also 0.01 or more and 1.3 or less. It is preferable that it is 0.03 or more and 1.1 or less.

  In addition to the above components (a) to (c) or (d), the recording layer in the volume hologram recording medium of the present invention may include a polymerization initiator, a sensitizer, a chain transfer agent, and a plasticizer as necessary. An additive such as a colorant may be added. Further, a binder resin may be added as a binder in order to have a uniform film thickness and allow an interference film formed by polymerization by light irradiation to exist stably.

  The photopolymerization initiator as an optional component is not particularly limited as long as it is a compound having a function capable of initiating polymerization of the ene / thiol polymerization compound by pattern exposure.

Examples of the pattern exposure method include photomask exposure, phase mask exposure, interference exposure, and the like. Among these, when performing volume hologram recording, interference exposure is preferable.
The light source for the interference exposure is generally a laser beam having a high coherence, and may be a high sensitivity to the photopolymerization initiator. For example, an argon ion laser (458 nm, 488 nm, 514.5 nm), a krypton ion laser (647. 1 nm), Nd: YAG laser (532 nm), Nd: YVO ₄ laser (532 nm), InGaN laser (405 nm)
, He-Cd laser (325 nm, 442 nm) or the like is used.

  The radical photopolymerization initiator is not particularly limited as long as it is a compound that generates an active radical at the time of pattern exposure. For example, a benzoin compound, an α-aminoalkylphenone compound, a thioxanthone compound, an azo compound, an azide compound , Acylphosphine oxide compounds, oxime ester compounds, organic peroxides, benzophenones, biscoumarins, bisimidazole compounds, titanocene compounds, trichloromethyltriazine compounds, or onium salt compounds such as iodonium salt compounds and sulfonium salt compounds. Used. Of these, titanocene compounds are preferred.

  The said photoinitiator may be used independently and may mix and use 2 or more types as needed.

The titanocene compound is not particularly limited. Specifically, bis (cyclopentadienyl) dichlorotitanium, bis (cyclopentadienyl) diphenyltitanium, bis (cyclopentadienyl) bis (2,3,4) , 5,6-pentafluorophenyl) titanium, bis (cyclopentadienyl) bis (2,3,5,6-tetrafluorophenyl) titanium, bis (cyclopentadienyl) bis (2,4,6-tri Fluorophenyl) titanium, bis (cyclopentadienyl) bis (2,6-difluorophenyl) titanium, bis (cyclopentadienyl) bis (2,4-difluorophenyl) titanium, bis (methylcyclopentadienyl) bis (2,3,4,5,6-pentafluorophenyl) titanium, bis (methyl) Cyclopentadienyl) bis (2,3,5,6-tetrafluorophenyl) titanium, bis (2,6-difluorophenyl) bis (methylcyclopentadienyl) titanium, bis (cyclopentadienyl) bis (2 , 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium and the like.

  Examples of the benzoin compound include benzoin ethyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane- 1-one etc. can be mentioned.

  Examples of the α-aminoalkylphenone compounds include 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- ( 4-morpholinophenyl) butan-1-one and the like.

  Examples of the thioxanthone compound include thioxanthone, 1-chlorothioxanthone, 2-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, and 2,4-diethylthioxanthone. Can do.

  Examples of the azo compound include 2,2′-azobis (2-aminodipropane) hydrochloride, 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (N- (2 -Carboxyethyl) -2-methylpropionamidine), dimethyl 2,2'-azobisisobutyrate, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile) ), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methyl-N- (2- (1 -Hydroxybutyl)) propionamide), 2,2'-azobis (2-methyl-N- (2-hydroxyethyl) -propionamide), 2,2'-azobis (2- (5-methyl-2-imidazo) N-2-yl) propane) hydrochloride, 2,2′-azobis (2- (2-imidazolin-2-yl) propane) hydrochloride, 2,2′-azobis (2- (2-imidazoline-2-) Yl) propane) sulfate, 2,2′-azobis (2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane) hydrochloride, 2,2′-azobis (2- (1- ( 2-hydroxyethyl) -2-imidazolin-2-yl) propane) hydrochloride, 2,2′-azobis (2- (2-imidazolin-2-yl) propane) and the like.

  Examples of the azide compounds include p-azidobenzaldehyde, p-azidoacetophenone, p-azidobenzoic acid, p-azidobenzalacetophenone, 4,4′-diazidochalcone, 4,4′-diazidodiphenyl sulfide. 2,6-bis (4′-azidobenzal) -4-methylcyclohexanone, 4,4′-diazidostilbene, and the like.

  Examples of the acylphosphine oxide compound include bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

Examples of the oxime ester compound include 2- (O-benzoyloxime) -1- [4- (phenylthio) phenyl] -1,2-octanedione, 1- (O-acetyloxime) -1- [9. And -ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] ethanone.

  Examples of the organic peroxide include acetyl peroxide, benzoyl peroxide, lauroyl peroxide, and di-tert-butyl peroxide.

  Examples of the benzophenones include benzophenone, 4,4′-bis (diethylamino) benzophenone, 1,4-dibenzoylbenzene, 10-butyl-2-chloroacridone, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4 -Benzoyl diphenyl ether, 3,3 ', 4,4'-tetra (tert-butylperoxycarbonyl) benzophenone, etc. can be mentioned.

  Examples of the biscoumarin include 3,3′-carbonylbis (7- (diethylamino) -2H-chromen-2-one) and the like, which is a product of BC (CAS [63226-13-3- 1]).

  Examples of the bisimidazole compound include 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetrakis (3,4,5-trimethoxyphenyl) -1,2′-bi. Examples thereof include imidazole and 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole.

  The binder resin is preferably compatible with (a) an ene compound and (b) a thiol compound. Specific examples thereof include chlorinated polyethylene, polymethyl methacrylate, methyl methacrylate, and other (meth) acrylic compounds. Examples include copolymers with acid alkyl esters, copolymers of vinyl chloride and acrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, ethyl cellulose, and acetyl cellulose.

  In order to produce a volume hologram recording medium using the composition for volume hologram recording material of the present invention, (a) an ene compound, (b) a thiol compound and (c) fine particles or (d) a branched polymer are required. Depending on the condition, it is mixed with a sensitizer and / or a binder resin, and is applied as it is on a transparent substrate without solvent, or a solvent or additive is added to the mixture and mixed, and this is applied onto a transparent substrate and dried. Thus, a recording medium having a volume hologram recording layer formed on a transparent substrate is obtained. Furthermore, a transparent substrate or a protective layer for blocking oxygen may be provided on the recording layer, and the volume hologram recording layer may be arranged between two transparent substrates or between the transparent substrate and the protective layer.

The solvent is not particularly limited as long as it has sufficient solubility for the components used and gives good coating properties. For example, cellosolve such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, etc. Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol dimethyl ether and other propylene glycol solvents, acetic acid Butyl, amyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, ethyl pyruvate, ethyl 2-hydroxy Ester solvents such as sibutyrate, ethyl acetoacetate, methyl lactate, ethyl lactate, methyl 3-methoxypropionate, alcohol solvents such as butanol, heptanol, hexanol, diacetone alcohol, furfuryl alcohol, methyl isobutyl ketone, cyclohexanone, methyl Ketone solvents such as amyl ketone, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-
Examples thereof include highly polar solvents such as pyrrolidone, mixed solvents thereof, and those obtained by adding aromatic hydrocarbons thereto.

  The ratio of the amount of the solvent used is usually in the range of about 1 to 20 times in terms of mass ratio with respect to the total amount of the volume hologram material composition of the present embodiment.

  As the transparent substrate, a transparent glass plate, an acrylic plate, a polyethylene terephthalate film, a polyethylene film, or the like is used. As a coating method, conventionally known methods such as spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, curtain coating and the like can be used.

  As the protective layer, a known technique for preventing adverse effects such as a decrease in sensitivity due to oxygen and deterioration in storage stability, for example, application of a water-soluble polymer or the like can be used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these Examples at all.

<Reference Example 1>
[Production of branched polymer (HB-TFA29) having a structural unit represented by the following formula (1)]

Under air, 5.90 g (17 mmol) of 9,9-bis (4-aminophenyl) fluorene (manufactured by Aldrich) was charged into a 200 mL four-necked flask, and 80 mL of dimethylacetamide was added and dissolved. Thereafter, this solution was heated to 100 ° C. in an oil bath, and 3.69 g of 2,4,6-trichloro-1,3,5-triazine (manufactured by Tokyo Chemical Industry Co., Ltd.) separately dissolved in 20 mL of dimethylacetamide ( 20 mmol) was added to initiate the polymerization. After 5 minutes, 3.35 g (36 mmol) of aniline was added to the reaction solution, and the mixture was further stirred for 10 minutes. Then, after allowing to cool to room temperature, this reaction solution was added to 1 L of an aqueous solution in which 15 g (0.11 mol) of potassium carbonate was dissolved, and reprecipitated. The precipitate was filtered, redissolved in 50 mL of tetrahydrofuran (THF), and then reprecipitated with a mixed solution of 540 mL of hexane and 60 mL of ethanol. The obtained precipitate was filtered and dried under reduced pressure at 40 ° C. for 6 hours to obtain 10.8 g of the intended HB-TFA29. The ¹ H NMR spectrum of the obtained HB-TFA29 is shown in FIG. Moreover, the weight average molecular weight Mw measured by polystyrene conversion by the gel permeation chromatography of the obtained compound was 2,900, and dispersion degree: Mw / Mn was 1.68. Here, Mn represents a number average molecular weight.

[Gel permeation chromatography (GPC) conditions]
Equipment: HLC-8200 GPC manufactured by Tosoh Corporation
Column: Shodex KF-804L + KF-805L
Column temperature: 40 ° C
Solvent: Tetrahydrofuran Detector: UV (254 nm)
Calibration curve: Standard polystyrene

<Example 1>
[Preparation of composition for volume hologram recording material]
To 1.05 g of silica dispersion (methyl isobutyl ketone dispersion, silica fine particle concentration 30.5% by mass, product name MIBK-ST, manufactured by Nissan Chemical Industries, Ltd.), (a) ene compound, trimethylolpropane diallyl ether ( Aldrich 0.16 g, and bis (cyclopentadienyl) bis (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium (Ciba Japan Co., Ltd., trade name Irgacure 784) ) 7.2 mg and benzoyl peroxide 9 mg were added and dissolved. Next, 0.2 g of trimethylolpropane tris (3-mercaptopropionate) (manufactured by Aldrich) is added to this solution as a thiol compound and sufficiently stirred at room temperature to obtain a composition for volume hologram recording material. Prepared.

At a wavelength of 546 nm, the refractive index of the silica fine particles was 1.46, the refractive index of the polymer of the ene compound and the thiol compound was 1.52, and the refractive index difference between the two was 0.06.
The density of the ene compound is 0.955 g / cm ³ and the density of the thiol compound is 1.21 g.
/ Cm ³ , and the density of the silica fine particles is 2.22 g / cm ³ , so that the volumes are the ene compound 0.16 / 0.955 = 0.168 cm ³ and the thiol compound 0.2 / 1.21 =
It was 0.165 cm ³ and silica fine particles 1.05 × 0.305 / 2.22 = 0.144 cm ³ .
Therefore, the volume fraction of the silica fine particles in the total volume of the ene compound, the thiol compound and the silica fine particles was 0.144 / (0.168 + 0.165 + 0.144) = 0.30, that is, 30% by volume.

[Production of volume hologram recording medium]
A polyethylene terephthalate film having a thickness of 50 μm was pasted on both ends of the slide glass as a spacer, and the composition for volume hologram recording material was dropped onto the center of the slide glass (region sandwiched between the spacers). Then, it dried for 20 minutes at 50 degreeC in oven, and formed the volume hologram recording layer. Thereafter, another slide glass was placed so as to sandwich the formed volume hologram recording layer, thereby producing a volume hologram recording medium.

[Measurement of physical properties during volume hologram recording]
The volume hologram recording medium of the present invention was subjected to two-beam interference exposure using the apparatus shown in FIG. ^Two- beam interference exposure (grating spacing 1 μm) was performed on the volume hologram recording medium with an exposure power density of 5 mW / cm ² using an Nd: YVO ₄ laser with a wavelength of 532 nm. The light emitted from the Nd: YVO ₄ laser passes through a beam expander and is divided into two by a half mirror and is irradiated to the volume hologram recording medium through each mirror, and interference fringes of both lights are recorded to form a volume hologram. .
At the same time, the volume hologram recording medium is irradiated with a helium-neon (He-Ne) laser with a wavelength of 632.8 nm, which is not exposed to light, and the hologram formation process is monitored and detected by detecting the diffracted light with a photodetector. Efficiency was evaluated. Further, the angle dependency of the diffraction efficiency after exposure was measured, and the film thickness after exposure of the sample was calculated. Further, the refractive index modulation amount (Δn) was evaluated from the obtained diffraction efficiency and film thickness.

The volume hologram recording medium after exposure was irradiated with a helium-neon (He—Ne) laser having a wavelength of 632.8 nm, and the scattering loss was evaluated from the ratio of incident light and (diffracted light + transmitted light).
Furthermore, a Bragg angle when a plurality of volume holograms are recorded while the perpendicular of the hologram recording medium surface is tilted by a finite angle from the bisector of the angle formed by the two light beams to be recorded, and the recorded holograms are read out. From the detuning, the volume shrinkage of the hologram recording layer was evaluated. Details of this shrinkage measurement method are described in Dhar, Applied Physics Letters 73, 1337-1339 (1998). The above results are shown in Table 1.

<Example 2>
A sample having a volume fraction of 5% by volume of silica fine particles was prepared in the same manner as in Example 1, and the volume shrinkage rate was evaluated. The results are shown in Table 1.

<Example 3>
Samples having a volume fraction of 10% by volume of silica fine particles were prepared in the same manner as in Example 1, and each physical property value was evaluated. The results are shown in Table 1.

<Example 4>
Samples having a volume fraction of silica fine particles of 20% by volume were prepared in the same manner as in Example 1, and each physical property value was evaluated. The results are shown in Table 1.

<Example 5>
Samples with a volume fraction of silica fine particles of 40 volume% were prepared in the same manner as in Example 1, and the physical property values were evaluated. The results are shown in Table 1.

< Reference Example 6>
[Preparation of composition for volume hologram recording material]
75 parts by mass of tetrahydrofuran was added to 25 parts by mass of HB-TFA29 produced in Reference Example 1, and the mixture was stirred at room temperature until a uniform solution was obtained. To 0.33 g of the obtained HB-TFA29 dispersion (branched polymer concentration 25.0 mass%), (a) 63 mg of pentaerythritol allyl ether (technical grade 70%, manufactured by Aldrich) as ene compound, and bis (cyclo Pentadienyl) bis (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium (Ciba Japan Co., Ltd., trade name Irgacure 784) 3.2 mg and benzoyl peroxide 4.1 mg Added and dissolved. Next, 0.1 g of trimethylolpropane tris (3-mercaptopropionate) (manufactured by Aldrich) is added to this solution as a thiol compound, and the mixture is sufficiently stirred at room temperature to obtain a volume hologram recording material composition. Prepared.

At a wavelength of 546 nm, the refractive index of HB-TFA29 was 1.73, the refractive index of the polymer of the ene compound and the thiol compound was 1.53, and the refractive index difference between the two was 0.20.
The density of the ene compound is 0.985 g / cm ³ and the density of the thiol compound is 1.21 g.
/ Cm ³ , and the density of HB-TFA 29 is 1.29 g / cm ³ , so that the volumes thereof are the ene compound 0.063 / 0.985 = 0.064 cm ³ and the thiol compound 0.1 / 1.
21 = 0.083 cm ³ , HB-TFA29 0.33 × 0.250 / 1.29 = 0.0
It was 64 cm ³ .
Therefore, the volume fraction of HB-TFA29 in the total volume of the ene compound, thiol compound and HB-TFA29 was 0.064 / (0.064 + 0.083 + 0.064) = 0.30, that is, 30% by volume. .

[Production of volume hologram recording medium]
Using the volume hologram recording material composition obtained in Reference Example 6, a volume hologram recording medium was produced in the same manner as in Example 1.

[Measurement of physical properties during volume hologram recording]
The physical property values of the volume hologram recording medium produced using the composition for volume hologram recording material obtained in Reference Example 6 were evaluated in the same manner as in Example 1. The results are shown in Table 2. In addition, FIG. 7 shows a change in the exposure time of the diffraction efficiency, and FIG. 8 shows a change in the exposure time of the refractive index modulation amount.

< Reference Example 7>
A sample having a volume fraction of 35% by volume of HB-TFA29 was prepared in the same manner as in Reference Example 6, and each physical property value was evaluated. The results are shown in Table 2. Further, FIG. 9 shows a change in the exposure time of the diffraction efficiency, and FIG. 10 shows a change in the exposure time of the refractive index modulation amount.

< Reference Example 8>
[Preparation of composition for volume hologram recording material]
To 0.33 g of the HB-TFA29 dispersion (branched polymer concentration 25.0% by mass) prepared in Reference Example 6, (a) 69 mg of pentaerythritol allyl ether (technical grade 70%, manufactured by Aldrich) as the ene compound, and Bis (cyclopentadienyl) bis (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium (trade name Irgacure 784, manufactured by Ciba Japan Ltd.) and benzoyl peroxide 4 .2 mg was added and dissolved. Next, 0.1 g of pentaerythritol tetrakis (3-mercaptopropionate) (manufactured by Aldrich) is added to this solution as a thiol compound and sufficiently stirred at room temperature to prepare a volume hologram recording material composition. did.

At a wavelength of 546 nm, the refractive index of HB-TFA29 was 1.73, the refractive index of the polymer of the ene compound and the thiol compound was 1.54, and the refractive index difference between the two was 0.19.
The density of the ene compound is 0.985 g / cm ³ and the density of the thiol compound is 1.28 g.
/ Cm ³ , and the density of HB-TFA 29 is 1.29 g / cm ³ , so that the volumes thereof are the ene compound 0.069 / 0.985 = 0.070 cm ³ and the thiol compound 0.1 / 1.
28 = 0.078 cm ³ , HB-TFA29 0.33 × 0.250 / 1.29 = 0.0
It was 64 cm ³ .
Therefore, the volume fraction of HB-TFA29 in the total volume of the ene compound, the thiol compound and HB-TFA29 was 0.064 / (0.070 + 0.078 + 0.064) = 0.30, that is, 30% by volume. .

[Production of volume hologram recording medium]
Using the volume hologram recording material composition obtained in Reference Example 8, a volume hologram recording medium was produced in the same manner as in Example 1.

[Measurement of physical properties during volume hologram recording]
The physical property values of the volume hologram recording medium produced using the composition for volume hologram recording material obtained in Reference Example 8 were evaluated in the same manner as in Example 1. The results are shown in Table 2. In addition, FIG. 11 shows a change in the exposure time of the diffraction efficiency, and FIG. 12 shows a change in the exposure time of the refractive index modulation amount.

< Reference Example 9>
A sample having a volume fraction of 35% by volume of HB-TFA29 was prepared in the same manner as in Reference Example 8, and each physical property value was evaluated. The results are shown in Table 2. FIG. 13 shows the change in the exposure time of the diffraction efficiency, and FIG. 14 shows the change in the exposure time of the refractive index modulation amount.

<Comparative example>
[Preparation of composition for volume hologram recording material]
To 10.0 g of silica dispersion (methyl isobutyl ketone dispersion, solid content concentration 30.5% by mass, product name MIBK-ST, manufactured by Nissan Chemical Industries, Ltd.), bis (cyclopentadienyl) bis (2,6- 32 mg of difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium (Ciba Japan Co., Ltd., trade name Irgacure 784) was added and dissolved. Next, 3.19 g of p-bis (β-methacryloyloxyethylthio) xylylene was added as a polymerizable compound to the solution to prepare a uniform solution, thereby preparing a photosensitive composition.

Since the density of the polymerizable compound is 1.13 g / cm ³ , the volume is 3.19 / 1.13.
= 2.82 cm ³ . On the other hand, the density of the silica fine particles because it is 2.22 g / cm ^3, the volume was ^{10.0 × 0.305 / 2.22 = 1.37cm 3} .
Therefore, the volume fraction of the silica fine particles in the total volume of the polymerizable compound and the silica fine particles was 1.37 / (2.82 + 1.37) = 0.33, that is, 33% by volume.

[Production of volume hologram recording medium]
A volume hologram recording medium was produced in the same manner as in Example 1 except that the drying conditions were changed to 80 ° C. for 30 minutes.

[Measurement of physical properties during hologram recording]
Each physical property value was evaluated in the same manner as in Example 1 except that the exposure intensity was changed to 100 mW / cm ² . The results are shown in Table 1.

  As shown in Table 1, when the volumetric shrinkage of the composition for volume hologram recording material of the present invention is extremely low and the volume fraction of the fine particles is about the same (Example 1 vs. Comparative Example), The volume shrinkage is about 1/8.

As shown in Table 2, the volume shrinkage ratio of the composition for volume hologram recording material of the present invention is extremely low, which is about 1/10 of the volume shrinkage ratio of the conventional composition ( Reference Example 6 vs. Comparative Example).

  The composition for volume hologram recording material of the present invention and the volume hologram recording medium obtained from them can be used for three-dimensional image display, large-capacity memory for images and bit information, diffractive optical elements, and the like.

1 hologram recording medium 2 Nd: YVO ₄ laser 3 beam expander 4 the He-Ne laser 5,6,7,8,9,10,11 mirror 12 the beam sampler 13 half mirrors 14 and 15 half-wave plates 16 and 17 polarizing prism 18, 19, 20 Photodetector

Claims (10)

A volume hologram recording material composition for recording interference fringes caused by coherent light interference by a difference in refractive index, wherein (a) an allyl alcohol derivative having at least two allyl groups, (b) a mercapto group thiol compound having at least two and (c) a particle size of 1nm or more, viewed contains fine particles is 100nm or less, the interference exposure of light, with the progress of polymerization of components (a) and component (b) (c) A composition for volume hologram recording material , in which fine particles move from a bright part to a dark part to form interference fringes having different refractive indexes .   The difference between the refractive index of the polymer of the (a) allyl alcohol derivative and the (b) thiol compound and the refractive index of the (c) fine particles is 0.01 or more and 1.3 or less. The composition for volume hologram recording materials described in 1.   The composition for a volume hologram recording material according to claim 1, wherein the fine particles (c) are inorganic fine particles.   The composition for a volume hologram recording material according to claim 3, wherein the fine particles (c) are silica fine particles.   The composition for a volume hologram recording material according to claim 1, wherein the fine particles (c) are organic fine particles.   The composition for a volume hologram recording material according to claim 5, wherein the fine particles (c) are hyperbranched polymers. The proportion of the (c) fine particles in the total volume of the (a) allyl alcohol derivative, the (b) thiol compound and the (c) fine particles is 3% by volume or more and 50% by volume or less.
The composition for a volume hologram recording material according to any one of claims 1 to 6. A volume hologram recording layer comprising the composition according to any one of claims 1 to 7 . A volume hologram recording medium comprising the volume hologram recording layer according to claim 8 . The volume hologram recording medium according to claim 9 , wherein the volume hologram recording layer has a structure in which the volume hologram recording layer is disposed between two transparent substrates.

Images