JPH0868907A - Difraction grating and its forming method - Google Patents

Abstract

PURPOSE: To obtain stable spaces among particles with good reproducibility, to make the distribution of diameters uniform, and to obtain excellent transparency, moisture resistance and storage stability by preparing hollow particles to have the diameter of the max. cross section smaller than the wavelength of visible light. CONSTITUTION: This grating is a hologram comprising a high refractive index layer and a low refractive index layer. The high refractive index layer and the low refractive index layer are formed by changing the density of hollow particles. The diameter of the max. cross section of hollow particles is smaller than the wavelength of visible light. These hollow particles are hollow polymer particles having a submicron-order particle size and prepared by emulsion polymn. The diameter of the max. cross section is smaller than the wavelength of visible light. If the diameter is larger than the wavelength of visible light, it is not preferable because particles reflect visible light. By densely dispersing hollow particles the inside of which are filled with air, the layer is made to have lower refractive index. In the obtd. layer, good modulation intensity of the refractive index is obtd. compared to the high refractive index layer having a sparse state of particles. Thus, a higher diffraction efficiency can be obtd. By preparing the particles with uniform particle size not to reflect visible light, good transparency can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram diffraction grating composed of a high refractive index layer and a low refractive index layer, or a diffraction grating composed of a multilayer film composed of a high refractive index film and a low refractive index film,
The present invention relates to a transparent diffraction grating having high diffraction efficiency, and to a diffraction grating used for automobile displays, heat ray reflective films, and the like.

[0002]

2. Description of the Related Art A diffraction grating having interference fringes formed thereon,
That is, there is a hologram and a method in which two kinds of substances having different refractive indexes are alternately laminated.

In the case of a diffraction grating using a hologram, conventionally,
Many materials such as bleached silver salts, dichromated gelatin, photopolymers, photoresists, thermoplastics, inorganic glasses, and ferroelectrics have been proposed as hologram materials. Of these, bleached silver salts and dichromated gelatin have reached the level of practical use to some extent, but bleached silver salts still have a lot of noise in the hologram, and bleaching is required in addition to normal processing. . Further, the bleached silver salt has a problem that it is inferior in durability such as moisture resistance and light resistance. In addition, dichromated gelatin has excellent hologram characteristics such as high refractive index modulation, that is, high diffraction efficiency, high resolution, and high transparency, but the hologram has poor moisture resistance and storage. Defects in stability and manufacturing stability have been pointed out.

Therefore, recently, many materials using organic materials have been proposed. The material using an organic material can be roughly classified into a material utilizing a photocrosslinking reaction and a material utilizing a photopolymerization reaction. As a material utilizing a photocrosslinking reaction, a material composed of a polymer containing a carbazole ring and a halogen-containing compound has been proposed in JP-A-53-15153.
For example, a hologram film is exposed to a photosensitive film made of poly-N-vinylcarbazole and carbon tetraiodide and having a thickness of 4 μm, and then a solvent treatment is performed to obtain a high diffraction efficiency of 90%.

Many materials have been proposed as materials utilizing photopolymerization reaction. For example, JP-A-2-2161
In Japanese Patent Publication No. 80, a material composed of poly-N-vinylcarbazole, a polyfunctional monomer and a photopolymerization initiator is proposed. For example, tris (acryloyloxyethyl) isocyanurate as a polyfunctional monomer and 3 as a polymerization initiator. , 3 ′, 4,4 ′-[Tetra (t-butylperoxycarbonyl) benzophenone] and 3,3′-carbonibis (7-diethylaminocoumarin) were subjected to hologram exposure of a photosensitive film having a thickness of 9 μm, and subjected to solvent treatment. By doing so, a diffraction efficiency of about 80% is obtained.

In Japanese Patent Publication No. 60-502125,
A material composed of an ethylenically unsaturated monomer, a sensitizer and a branched polyethyleneimine has been proposed.
A film thickness of poly-N-vinylpyrrolidone as a binder, Li acrylate as an unsaturated monomer, branched polyethyleneimine and methylene blue as a photosensitizer, etc. 5
After the hologram exposure of the photosensitive film having a thickness of μm, a solvent treatment is performed to obtain a diffraction efficiency of about 60%.

[0007] For these materials, a wet development process called immersion in a solvent is indispensable in order to realize the refractive index modulation, but on the other hand, materials which do not require a step of immersion in a solvent have been proposed. U.S. Pat. No. 3,694,218 proposes a material comprising an ethylenically unsaturated monomer such as a metal acrylate and a photopolymerization initiator. Barium acrylate is used as the metal acrylate and toluene sulfone is used as the polymerization initiator. Liquid materials using sodium acid salt, etc.
By enclosing it between glass plates of 20 μm and hologram-exposing it, a diffraction efficiency of about 3% is obtained.

US Pat. No. 3,658,526 proposes a material using an ethylenically unsaturated monomer having a boiling point of 100 ° C. or higher, a binder and a free radical polymerization initiator. A hologram is produced by exposing a material using triethylene glycol diacrylate as an unsaturated monomer, cellulose acetate butyrate as a binder, and an imidazoyl dimer compound as a polymerization initiator.

Further, in JP-A-2-3081, a binder is cellulose acetate butyrate, and an ethylenically unsaturated monomer is 2-phenoxyethyl acrylate and N.
As a mixture of vinylcarbazole, a photosensitive film having a film thickness of 10 μm has a diffraction efficiency of 53%.

Further, in Japanese Patent Laid-Open No. 3-36582,
A material consisting of allyl diglycol carbonate, 2,2-bis [3,5-dibromo-4- (2-methacryloyloxyethoxy) phenyl] propane and a photopolymerization initiator is sandwiched between glass plates and exposed after heating. The diffraction efficiency is about 40%.

As described above, although various hologram materials have been proposed, at present, materials exhibiting characteristics comparable to those of dichromated gelatin in terms of hologram characteristics such as refractive index modulation strength and transparency of hologram film. However, the conventional hologram material still has some points to be improved.

Further, in the case of a diffraction grating obtained by alternately laminating two kinds of material layers having different refractive indexes, a fluorine-containing resin [eg, a product name of Asahi Kasei Co., Ltd. CYTOP, etc., refractive index 1.34]
Compounds such as magnesium fluoride (MgF ₂ , refractive index 1.38) and the like are used, but the refractive index is at most about 1.3, and it was not possible to obtain a lower one.

Further, in the ultrafine particle dispersed material in which the ultrafine particles are dispersed in the resin, the refractive index thereof can take only a value between the refractive index of the magnesium material and the refractive index of the ultrafine particles, Even if ultrafine particles of magnesium fluoride are used, a value of 1.38 or less cannot be obtained.

[0014]

In the case of a hologram diffraction grating, conventional wet materials (bleached silver salt, dichromated gelatin or futopolymer requiring a developing step) are
Although it has the advantage that the refractive index modulation intensity is large, it is difficult to control the stability of the size of voids, reproducibility, and the diameter distribution, and there is a lot of noise, and the transparency of the hologram film is poor, or heavy chromium gelatin. Has good transparency, but has a problem of poor moisture resistance and storage stability. Conventional dry materials (which do not require a development process and can obtain a refractive index distribution by diffusing a monomer) have excellent transparency, moisture resistance, and storage stability. There is a problem that the rate modulation intensity is small.

Further, in the case of a diffraction grating formed of a multilayer film,
The larger the difference in refractive index between the low refractive index film and the high refractive index film, the higher the diffraction efficiency, and the lower the refractive index film, the higher the refractive index of air (= 1).
The closer to, the greater the effect. For that purpose, a material having a low refractive index which has never been obtained is required.

The present invention is, firstly, a system utilizing a photopolymerization reaction, in which the size of voids is stable, the reproducibility is good, the diameter distribution can be made uniform, the refractive index modulation strength is large, and the transparency is high. ,
It is an object of the present invention to provide a hologram diffraction grating having excellent moisture resistance and storage stability.

A second object of the present invention is to provide a diffraction grating having a multilayer film which is transparent and has a high diffraction efficiency which has never been obtained.

[0018]

According to the present invention, in the case of a hologram diffraction grating, a non-polymerized monomer is removed by development to obtain a refractive index difference (wet type), or a refractive index distribution is obtained by diffusion of a monomer during polymerization. The present invention was completed by discovering that a hollow particle is present in the dark part or the bright part of the interference fringes instead of the obtained (dry) method, and that a diffraction grating that is more transparent and has higher diffraction efficiency than conventional holograms can be obtained. It was done.

The present invention is also applicable to a diffraction grating formed of a multilayer film. By dispersing hollow particles instead of ultrafine particles in the matrix material of the low refractive index film, a refractive index lower than that of the matrix material can be obtained. The inventors have found that a transparent diffraction grating having a high diffraction efficiency can be obtained by obtaining a large difference in refractive index from the high refractive index film, thus completing the present invention.

That is, the first diffraction grating of the present invention is a hologram composed of a high refractive index layer and a low refractive index layer, and the high refractive index layer and the low refractive index layer are formed by sparse and dense hollow particles. The diameter of the maximum cross-sectional area of the hollow particles is equal to or less than the visible light wavelength.

Further, the low refractive index layer is a portion where the interference lights at the time of hologram recording are weakened.

Further, the low refractive index layer is a portion where the interference lights during hologram recording are mutually strengthened.

The second diffraction grating of the present invention is a multilayer film in which a high refractive index film and a low refractive index film are laminated, wherein the low refractive index film contains hollow particles and the maximum cutoff of the hollow particles. The diameter of the area is less than or equal to the visible light wavelength.

Further, the high refractive index film is characterized by being laminated on the low refractive index film by coating.

Further, the high refractive index film is characterized by being laminated on the low refractive index film by extrusion molding.

Further, the above-mentioned first and second diffraction grating pitches are characterized in that they are 200 to 700 nm.

Further, the hollow particles in the first and second diffraction gratings have a shape of a flat sphere, and the minor axis direction thereof is present in the same direction as the film thickness direction of the diffraction grating.

In the first method for forming the first diffraction grating of the present invention, laser light interference fringes are formed on a recording medium composed of hollow particles, a photopolymerizable monomer, a binder polymer and a photopolymerization initiator. As such, the photopolymerizable monomer in the portion where the interference light strengthens is polymerized to cause the hollow particles to diffuse and move to the portion where the interference light weakens, after-exposure, and the portion where the interference light weakens is polymerized, The high refractive index layer is a portion where the interference light is strengthened, and the low refractive index layer is a portion where the interference light is weakened.

The second method for forming the first diffraction grating of the present invention comprises hollow particles, a photopolymerizable monomer, a binder polymer, and a photopolymerization initiator, and the hollow particles are photopolymerizable on the outside. The recording medium is a hollow particle having a functional group,
Irradiate laser light so as to form interference fringes, polymerize the photopolymerizable monomer in the area where the interference light strengthens with the photopolymerizable functional group in the hollow particles, and diffuse and move the hollow particles to the area where the interference light strengthens. After that, post-exposure to polymerize the photopolymerizable monomer in the part where the interference light weakens, and make the part where the interference light strengthens a low refractive index layer, and the part where the interference light weakens a high refractive index layer. Is characterized by.

The third method of forming the first diffraction grating of the present invention comprises hollow particles, a binder polymer and a photopolymerization initiator, the hollow particles having a photopolymerizable functional group on the outside thereof. The recording medium is irradiated with laser light so as to form interference fringes, and the photopolymerizable functional groups in the hollow particles are polymerized at the portions where the interference lights are strengthened, and the hollow particles are diffused and moved to the portions where the interference lights are strengthened. It is characterized in that the portion where the interference light is strengthened is a low refractive index layer and the portion where the interference light is weakened is a high refractive index layer.

In the above first method for forming a diffraction grating, the hollow particles have a filling material therein, and after the diffraction grating is formed, the filling material in the hollow particles is selectively removed,
It can be a hollow particle.

The first diffraction grating of the present invention and the method for forming the same will be described.

The hollow particles in the present invention are hollow polymer particles having a particle size of submicron order obtained by emulsion polymerization, and the diameter of the maximum cross-sectional area thereof is below the visible light wavelength, that is, below 300 nm, preferably below 10 nm. ~
It is 100 nm. If the diameter of the maximum cross-sectional area of the hollow particles is not less than the visible light wavelength, visible light is reflected, which is not preferable.

Such hollow particles are disclosed, for example, in JP-A-2-
Which is obtained by seed emulsion polymerization described in Japanese Patent No. 300204, using polystyrene emulsion as seed particles and a mixed monomer of methyl methacrylate / divinylbenzene as a polymerization monomer.
It is obtained by allowing the seed particles to absorb a monomer before the initiation of polymerization to form an aqueous dispersion of seed particles / monomer solution, and then polymerizing with a water-soluble polymerization initiator.

The hollow portion inside the hollow particles may be a single hollow type (one hollow portion exists inside the resin particle) or a multi-hollow type (a plurality of hollow portions exist inside the resin particle). However, the single hollow type is preferable from the viewpoint of increasing the air portion. The hollow diameter is 1/10 to 3/4 of the particle diameter.

Examples of the polymer forming the hollow particles include styrene-acrylic copolymer resin and styrene resin. The shell portion of the resin particles may be non-porous type having no fine pores, but may have fine pores. With the porous type, it is possible to remove the filling material inside the hollow particles after forming the hologram or the multilayer film.

The recording medium used in the first forming method is
It is composed of the hollow particles, the photopolymerizable monomer, the binder polymer, and the photopolymerization initiator described above.

Examples of the photopolymerizable monomer include monomers having at least one ethylenically unsaturated double bond in one molecule, oligomers, prepolymers and mixtures thereof. Specific examples thereof include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids with aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids with aliphatic polyhydric amine compounds. Specifically, as the unsaturated carboxylic acid, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and halogen-substituted unsaturated carboxylic acids thereof, for example, chlorinated unsaturated carboxylic acid, brominated Examples thereof include unsaturated carboxylic acid and fluorinated unsaturated carboxylic acid. Examples of the salts of unsaturated carboxylic acids include sodium salts and potassium salts of the above-mentioned acids.

As the ester of the aliphatic polyhydric alcohol compound and the unsaturated carboxylic acid, ethylene glycol diacrylate, triethylene glycol diacrylate,
1,3-butanediol diacrylate, tetramethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl)
Ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, diether Pentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer, 2-hydroxy Propyl acrylate, tetrahydrofurfuryl acrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, tetramethylene glycol dimethacrylate, propylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane Trimethacrylate, trimethylolethane trimethacrylate, hexanediol dimethacrylate, 1,4-cyclohexanediol dimethacrylate, tetraethylene glycol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate,
Dipentaerythritol dimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, sorbitol pentamethacrylate, sorbizol hexamethacrylate, bis- [p- (3- Methacryloxy-2-hydroxypropoxy) phenyl] dimethylmethane, bis- [p- (acryloxyethoxyphenyl] dimethylmethane], 2-hydroxypropyl methacrylate and the like can be mentioned.

As the itaconic acid ester, ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol itaconate, 1,4
-Butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate, sorbitol tetritaconate and the like.

As the crotonic acid ester, ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate,
And sorbitol tetracrotonate.

Examples of the isocrotonic acid ester include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate and sorbitol tetraisocrotonate.

Examples of the maleic acid ester include ethylene glycol dimaleate, pentaerythritol dimaleate and sorbizole tetramaleate.

As the halogenated unsaturated carboxylic acid,
2,2,3,3-tetrafluoropropyl acrylate, 1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 1H, 1H, 2H, 2H-heptadeca Examples thereof include fluorodecyl methacrylate.

Examples of amides of unsaturated carboxylic acid and aliphatic polyvalent amine compound include methylenebisacrylamide, methylenebismethacrylamide, 1,6-hexamethylenebisacrylamide, 1,6-hexamethylenemethacrylamide, Diethylenetriamine tris acrylamide, xylylene bis acrylamide, xylylene bis methacrylamide, acrylamido butyraldehyde dimethyl acetal and the like can be mentioned.

Other examples include Japanese Examined Patent Publication No. 48-417.
Polyisocyanate compound having two or more isocyanate groups in one molecule described in JP-A-08, the following general formula CH ₂ ═C (R) COOCH ₂ CH (R ₁ ) OH (wherein R and R ₁ are hydrogen A vinyl urethane compound having two or more polymerizable vinyl groups in one molecule to which a vinyl monomer having a hydroxyl group represented by an atom or a methyl group) is added.

Further, urethane acrylates described in JP-A-51-37193, JP-A-52-304
No. 90, Japanese Patent Publication No. 49-43191, and Japanese Patent Laid-Open No. 4
Polyester acrylates, epoxy resins and (meth) as described in JP-A 8-64183, respectively.
Mention may be made of polyfunctional acrylates such as acrylics and methacrylates.

Halides of epoxy acrylates such as fluorides and bromides can also be used. Furthermore, the Journal of Adhesion Society of Japan, Vol. 20, No7, 300-
Those introduced as photocurable monomers and oligomers on page 308 can also be used. For example, tribumophenoxyethyl acrylate, tribromophenol acrylate, tribromophenol methacrylate, tetrabromophenol acrylate, tetrabromobisphenol A di (meth) acrylate and the like can also be used. For example, Dai-ichi Kogyo Co., Ltd., trade name, New Frontier BR-31, Toa Gosei Chemical Co., Ltd., trade name, Aronix M-315 and M-
325, 2,2'-bis (4-acryloxydiethoxyphenyl) propane (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name, NK ester A-BPE-4), tetramethylolmethane tetraacrylate (Shin-Nakamura Chemical) Manufactured by
Trade names, NK ester A-TMMT) and the like can also be used.

As the binder polymer, polymethacrylic acid ester or its partial hydrolyzate, polyvinyl acetate or its hydrolyzate, polystyrene, polyvinyl butyral, polychloroprene, polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, poly- N-vinylcarbazole or a derivative thereof, poly-N-vinylpyrrolidone or a derivative thereof, a copolymer of styrene and maleic anhydride or a half ester thereof, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, acrylamide, acrylic Copolymers having a monomer selected from the group of copolymerizable monomers such as nitrile as a polymerization component, vinylcarbazole-styrene copolymers, vinylcarbazole-vinyl chloride copolymers, vinylcarbazole-methylmethacryl Rate copolymer, vinylcarbazole-vinylanthracene copolymer, vinylcarbazole-vinylpyridine copolymer, vinylcarbazole-acrylate copolymer, vinylcarbazole-ethylacrylate copolymer, vinylcarbazole-acrylonitrile copolymer, vinyl Carbazole-butyl acrylate copolymer, vinylcarbazole-nitrovinylcarbazole copolymer, nitrated poly-N-vinylcarbazole, polyvinylaminocarbazole, vinylcarbazole-N-methylaminovinylcarbazole copolymer, halogen-substituted poly-N- Vinylcarbazole, vinylcarbazole-dibromovinylcarbazole copolymer, polyiodovinylcarbazole, polybenzylidenevinylcarbazole, polypropenylcarbazo Le, and the like.

Examples of the photopolymerization initiator include triazines, benzoin alkyl ethers, ketals, oxime esters, benzophenones, thioxanthone derivatives, quinones, aromatic ketones such as thioacridone, and 1,3-
Alkyl or alkyl borate such as di (t-butyldioxycarbonyl) benzene, iodonium salts, dianine, rhodamine, safranine, malite green, methylene blue, iron-arene complex, bisimidazoles, N-arylglycine, etc. are used. be able to.

In order to increase the sensitivity of the photopolymerization initiator, it is desirable to use a system containing a visible light sensitizing dye. Examples of visible light sensitizing dyes include squarylium dyes, aromatic amines such as Michler's ketone, xanthene dyes, thiopyrylium salts, merosinin / quinoline dyes, coumarin / ketocoumarin dyes, acridine orange, benzoflavin, dianine, phthalocyanine, Porphin, rhodamine, safranine, malachite green, methylene glycol and the like are used.

Particularly preferred is the following general formula

[0053]

Embedded image

(Wherein R ₄ , R ₅ and R ₆ are each a hydrogen atom, or a chlorine atom, a lower dialkylamino group, a lower dialkenylamino group or an alicyclic amino group, and X is a total number of hydrogen atoms and heteroatoms. 5 to 9 heterocyclic groups or -COY
Indicates a group. Here, Y represents a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, a lower alkoxy group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted steryl group, or a substituted or unsubstituted 3'-coumarino group. . Z represents a hydrogen atom or a cyano group. ) Is a polymerization initiator system consisting of a coumarin compound and an organic peroxide.

In the above formula, R ₄ , R ₅ and R ₆ are preferably hydrogen atoms, chlorine atoms, lower alkoxy groups such as methoxy, ethoxy and butoxy, lower groups such as dimethylamino, diethylamino and N-methyl-N-propylamino. Examples thereof include dialkylamino groups, alicyclic amino groups such as N-monophorino and N-piperidino, and lower dialkenylamino groups such as dipropenylamino, di, (α-methylpropenyl) amino groups.

The heterocyclic group for X is 2-imidazole, 2-N-methylimidazole, 2-benzimidazole, 2- (4-phenyl) imidazole, 2-oxazole, 2-benzoxazole, 2- (4-phenyl). ) Oxazole, 2-thiazole, 2-benzthiazole, 2- (4-phenyl) thiazole, 2- (5-phenyl) thiadiazole, 2- (5-tolyl) thiadiazole, 2- (5-biphenyl) thiadiazole, 2-
Examples thereof include residues such as (5-phenyl) oxadiazole, 2-p-methoxyphenyl) oxadiazole, and 2- (5-p-chlorophenyoxadiazole).

As Y in the --COY group, methyl, ethyl, propyl, hexyl, β-cyanoethyl,
A substituted or unsubstituted C ₁ -C ₆ alkyl group such as ethoxycarbonylmethyl, butoxycarbonylmethyl, phenyl, p-cyanophenyl, p-methylphenyl, p-
A substituted or unsubstituted phenyl group such as methoxyphenyl and m-hydroxycarbonylphenyl, a steryl group such as steryl, p-methoxysteryl, p-cyanosteryl, and m-chlorsteryl, and the following general formula

[0058]

Embedded image

The 3-coumarino group represented by the formula (wherein R ₄ , R ₅ , R ₆ and Z are the same as those in the above chemical formula 1) can be mentioned.

Specific examples of the coumarin compound include 3-acetyl-7-dimethylaminocoumarin and 3-benzoyl-
7-dimethyl-aminocoumarin, 3-benzoyl-5,
7-dimethoxycoumarin, methyl 7-diethylamino-
3-coumarinoyl acetate, 3-cinnamoyl-7-
Diethylaminocoumarin, 3,3'-carbonylbis (7-diethylamino) coumarin, 3,3'-carbonylbis (5,7-dimethoxyamino) coumarin, 7-diethylamino-5,7'-dimethoxy-3,3'- Biscoumarin, 3- (2'-benzimidazoyl) -7-diethylaminocoumarin, 3- (2'-benzoxazoyl) -7-diethylaminocoumarin, 3- (5'-phenylthiadiazoyl-2 ')- 7-diethylaminocoumarin, 3- (2'-benzthiazoyl) -7-diethylaminocoumarin, 3,3'-carbonylbis (4-cyano-7-diethylamino) coumarin and the like can be mentioned.

The ratio of the triazine compound to the squarylium compound is 1 part by weight to 100 parts by weight, preferably 1 part by weight, relative to 1 part by weight of the squarylium compound.
It is used in the proportion of 50 parts by weight to 50 parts by weight.

The composition ratio of each component constituting the record carrier is such that 100 parts by weight of the binder polymer and 10 hollow particles are used.
Parts by weight to 1000 parts by weight, preferably 50 parts by weight to 20
0 parts by weight, 300 parts by weight or less of the photopolymerizable monomer, preferably 30 parts by weight to 150 parts by weight, 1 part by weight to 100 parts by weight, preferably 1 part by weight, including the photopolymerization initiator and the visible light sensitizing dye. -30 parts by weight is recommended.

In addition to the above composition, components such as an oxygen scavenger, a thermal polymerization inhibitor, a plasticizer and an ultraviolet absorber may be added to the recording medium.

Examples of the solvent include benzene, chlorobenzene, tetrahydrofuran, 1,4-dioxane,
1,2-dichloroethane, dichloromethane, chloroform and the like are used, but as a coating liquid, a binder polymer, a photopolymerizable monomer and the like are dissolved in these solvents and hollow particles are dispersed, and a glass plate, transparent A resin plate or a transparent resin film is applied by spinner coating, blade coating, roll coating, etc. and dried to a film thickness of 0.1 μm to 100 μm.
m, preferably 5 μm to 50 μm. The film thickness is adjusted by the concentration of the composition in the solvent, the film thickness at the time of coating, and the like. In some cases, coating and drying may be repeated several times to form a thick film. Furthermore, the support itself of the binder polymer itself may be used to form a film itself.

If the surface of the recording medium that is in contact with air is coated with an aqueous solution of polyvinyl alcohol or the like to block the contact with air, polymerization inhibition by oxygen does not occur and the sensitivity of the hologram is increased. Can be done.

The record carrier thus obtained is, for example, 457.9 nm, 488 nm, 514.7 nm, 52.
It is sensitive to laser light having emission lines at 8.7 nm, 647.1 nm, etc., and is 1 to 500 m for a krypton ion laser having a wavelength of 647.1 nm, for example.
The energy of J / cm ² gives diffraction efficiency in a practical range.

The diffraction grating pitch is 0.2 μm to 0.
If it is 7 μm, it can be used as a heat ray reflective film, and
A color hologram can also be formed by performing color recording.

According to this first forming method, when the recording medium is irradiated with laser light to form interference fringes, the monomer is polymerized in the bright portion of the interference fringes (the portion where the interference light is intensified), and at that time, hollow There is a phenomenon that particles are pushed out to a dark part (a part where interference light is weakened). Then, by heating, post-exposure with ultraviolet rays or electron beams, the remaining monomer is polymerized in the form of taking in the hollow fine particles that have become dense in the dark portion, whereby a hologram can be formed. That is, in the first forming method,
A high refractive index layer in which a photopolymerizable monomer is polymerized is obtained in the bright portion of the interference fringe, and a low refractive index layer filled with hollow particles is obtained in the dark portion of the interference fringe.

Further, a coating liquid comprising a photopolymerizable monomer and hollow particles can be used as a recording medium without using a binder polymer. In this case, hologram recording may be performed after the recording medium is sandwiched between two glass plates.
When the binder polymer is not used, as the recording medium, 1 part by weight to 1000 parts by weight, preferably 1 part by weight to 100 parts by weight of hollow particles, 100 parts by weight of the photopolymerizable monomer, a photopolymerization initiator and visible light are used. 1 part by weight to 100 parts by weight, preferably 1 part by weight to 5 parts by weight including the sensitizing dye.
It is recommended to set it to 0 parts by weight.

Next, the second method of forming the first diffraction grating will be described. The recording medium used in the second forming method is hollow particles having a photopolymerizable group on the outside of the shell,
A hollow polymer particle consisting of a photopolymerizable monomer, a binder polymer, and a photopolymerization initiator, which uses a hollow polymer particle having a photopolymerizable group on the outside of the shell forming the hollow particle, instead of the hollow particle used in the first forming method. Is.

The hollow particles are (1) a polymerizable vinyl monomer such as methyl methacrylate or methacrylate,
From a crosslinkable polymer having two or more vinyl groups such as divinylbenzene and ethylene glycol diacrylate,
Forming seed particles having a terminal vinyl group on the particle surface,
Then, a monomer such as methyl methacrylate or divinylbenzene is added and absorbed in the seed particles to form an aqueous dispersion of the seed polymer / monomer solution, and then the monomer is polymerized using a water-soluble polymerization initiator. A method of forming hollow particles having a terminal vinyl group on the particle surface, (2) adding an epoxy compound such as glycidyl methacrylate to a polymerizable vinyl-based monomer such as styrene and methyl methacrylate or methacrylate, and polymerizing it An aqueous dispersion of a seed polymer / monomer solution is formed by forming seed particles having a vinyl group on the particle surface, and then adding a monomer such as methyl methacrylate or divinylbenzene and absorbing the seed particles in the same manner as in (1) above. And then polymerize the monomers using a water-soluble polymerization initiator The terminal vinyl group can be produced by the method to form hollow particles having the particle surface or the like. Examples of the photopolymerizable group on the surface of the hollow particles include a vinyl group, an acryl group and a methacryl group.

Among the photopolymerizable monomers described in the first forming method, those having photopolymerizability with the photopolymerizable group bonded to the surface of the hollow particles are used. Further, as the binder polymer, the photopolymerization initiator and the like, those described in the above-mentioned first forming method are used in the same manner, and the same recording medium can be used, and the same recording conditions can be applied. .

According to the second forming method, when the recording medium is irradiated with laser light to form interference fringes, the monomer is polymerized while drawing in the photopolymerizable group bonded to the hollow particles in the bright portion of the interference fringe. The hollow fine particles are drawn into the bright part of the interference fringes. Next, heating, post-exposure with ultraviolet rays or electron beams is performed to cure the monomer in the dark portion of the interference fringes, and a hologram can be obtained.

Also in this second forming method, like the first forming method, a recording medium can be formed without using a binder polymer, and a hologram can be formed by sandwiching it between two glass plates. it can. The component ratio in the recording medium in that case is the same as that in the first forming method.

Next, a third method of forming the first diffraction grating of the present invention will be described. The recording medium used in the third forming method is composed of hollow particles having a photopolymerizable group on the outside of the shell, a binder polymer, and a photopolymerization initiator.

This method does not require the photopolymerizable monomer used in the second forming method, and the other components in the recording medium are the same as those in the recording medium used in the second forming method.

The composition ratio of each component constituting the record carrier is 1 part by weight to 1000 parts by weight, preferably 10 parts by weight to 200 parts by weight of hollow particles to 100 parts by weight of the binder polymer.
1 part by weight to 100 parts by weight, preferably 1 part by weight to 50 parts by weight, in combination with the photopolymerization initiator and the visible light sensitizing dye.

In this forming method, when the interference fringes are formed on the recording medium by laser light, the photopolymerizable groups attached to the outside of the hollow fine particles can be polymerized by photoreaction, and the hollow particles are formed in the bright portion of the interference fringes. Hollow particles can be drawn in, and hollow particles become coarse in the dark portion of the interference fringes to form a high refractive index layer made of a binder polymer, and a hologram can be obtained.

In this forming method, the hollow fine particles remaining in the dark portion of the interference fringes can be destroyed by heating after the laser exposure, and the refractive index can be further increased.

Next, the second diffraction grating of the present invention and the method for forming the same will be described. The second diffraction grating is a multilayer film in which a high refractive index film and a low refractive index film made of hollow particles are laminated.

As the low refractive index film in the second diffraction grating, a film obtained by uniformly exposing the recording medium used in the method for forming the first diffraction grating can be used, but the proportion of hollow particles can be increased. The composition of the low refractive index film is required to be 1 part by weight to 1000 parts by weight of hollow particles, preferably 10 parts by weight to 200 parts by weight, and 30 parts by weight of a photopolymerizable monomer to 100 parts by weight of the binder polymer. 300
The amount of the photopolymerization initiator and the visible light sensitizing dye is 1 part by weight to 100 parts by weight, preferably 1 part by weight to 30 parts by weight, preferably 30 parts by weight to 150 parts by weight.

As the low refractive index film when the binder polymer is not used, the photopolymerizable monomer 10 is used.
1 part by weight to 1000 parts by weight, preferably 10 parts by weight to 200 parts by weight, and 1 part by weight to 100 parts by weight of the photopolymerization initiator and the visible light sensitizing dye together, preferably 0 part by weight. It may be 1 to 50 parts by weight.

The second method for producing the diffraction grating is as follows. A low-refractive-index film coating liquid is applied onto a support, dried, and uniformly exposed to form a low-refractive-index film. On the film, after the photopolymerizable monomer and / or binder polymer used in the first diffraction grating is appropriately dissolved in a solvent, spinner coating, blade coating, roll coating or the like is applied, or after extrusion molding, A high refractive index film may be formed by curing or forming a film.

The film thickness of the low refractive index film and the film thickness of the high refractive index film are
After drying, the thickness can be adjusted to 0.2 μm to 0.7 μm, but it is preferable to stack 5 to 50 layers of a low refractive index film and a high refractive index film to form a multilayer film, for example, a diffraction grating pitch. Is 0.2 μm to 0.7 μm, only infrared rays can be reflected and visible light can be transmitted.
The hologram can be a multilayer film that is useful as a heat-reflecting film used for window glass of buildings and windshields of automobiles and as a greenhouse for agriculture. Further, it can be configured and used as a lens or a prism.

The first and second diffraction gratings have been described above. However, in any diffraction grating, if the diffraction grating is pressurized at a pressure of 5 Kg / cm ² to 50 Kg / cm ² in its film thickness direction. The hollow particles can be flattened with the minor axis direction as the film thickness direction, and the diffraction grating can be made more transparent.

When the hollow particles used for forming the diffraction grating contain a filling material in the hollow portion, after forming the diffraction grating, the filling material is removed by utilizing the porosity of the shell to remove the hollow portion. By using air, the refractive index of the low refractive index layer can be brought close to that of air (n = 1), and the diffraction efficiency can be further improved.

For example, when the packing is a photopolymerizable monomer, the diffraction grating is immersed in a solvent or the like to remove the photopolymerizable monomer, and then the solvent is removed by a drying treatment or the like to replace the inside with air or the like. Good.

When the filler is silica fine particles or a composite latex such as metal salt fine particles of copper sulfate, magnesium chloride, etc., after forming a diffraction grating, for example, in the case of silica fine particles, an aqueous ammonia solution is used. , Elute by immersing in an alkaline aqueous solution such as triethylamine, or in the case of metal salt fine particles, immerse in water to elute, and further remove the solvent by a drying treatment or the like to replace the inside with air etc. to form hollow particles. Good to do.

[0089]

The present invention has found that the high-refractive index layer and the low-refractive index layer in the diffraction grating can be formed by sparse and dense hollow particles filled with air inside. By densely dispersing the hollow particles filled with air to, the refractive index can be lowered, and the hollow particles have a higher refractive index modulation strength than the high refractive index layer in a coarse state,
It is possible to improve the diffraction efficiency. In addition, the hollow particles have a diameter equal to or less than the visible light wavelength and have a size that does not reflect visible light,
In addition, by making the particle diameters uniform, haze 1
When it is less than%, the transparency can be improved.

As described above, the diffraction grating of the present invention is opaque due to the disturbance of the film generated during development even if the high diffraction efficiency of the conventional wet material is obtained, and the transparency of the dry material is high. It is possible to solve the problem that the difference in refractive index cannot be obtained even if the property is obtained, a heat ray reflective film used for a window glass of a building or a windshield of an automobile, an agricultural vinyl house, and a high diffraction efficiency and It can be used as an optical component that requires transparency.

Examples of the diffraction grating of the present invention will be described below.

[0092]

Example 1 Poly-N-vinylcarbazole (manufactured by Anan Fragrance Industry Co., Ltd., Tubicor 210, Mw = 500,000 to 800,000, refractive index = 1.68) ... 1.0 g Tribromophenoxy Ethyl acrylate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., New Frontier BR-31) ... 1.0 g-Trichloro-s-triazine (Midori Kagaku Co., Ltd., TAZ-101) ... 0.07 g-squalilium -Based dye (NK-2990, λmax = 650 nm, manufactured by Nippon Senshoku Co., Ltd.) ... 0.002 g-Hollow particles (particle diameter 250 μm, inner pore diameter 50 μm) 1.4504 g in chlorobenzene 13.0536 g To obtain a hollow particle dispersion liquid, which was used as a photosensitive liquid.

This photosensitive solution was applied to a PET film
-7 W, 50 μm thick) A film was formed on a substrate with an applicator to a thickness of 0.1 mm (4 mils), and after standing still for 1 minute,
Dry in an oven, 70 ° C for 10 minutes, thickness: 7 μm
The recording medium of

Then, polyvinyl alcohol [PVA205, manufactured by Kuraray Co., Ltd., saponification degree: 88] was applied on the surface of the recording medium.
%, The degree of polymerization of 500], a 5% by weight pure aqueous solution was applied by a spinner (500 rpm / 5 sec → 1000 rpm /
Air dried for 20 sec).

Then, using the optical system shown in FIG. 4, krypton laser [647.1 nm] light was irradiated so that the exposure energy was 10 mJ / cm ² .

After exposure, ultraviolet rays were irradiated at 50 mJ / cm ² to polymerize the residual monomer.

The diffraction efficiency of the obtained hologram is 80%,
The reproduction wavelength was 1000 nm, the haze was about 1%, and the diffraction grating was transparent and had high diffraction efficiency.

[0098]

Example 2 Poly-N-vinylcarbazole (manufactured by Anan Fragrance Industry Co., Ltd., Tubicor 210, Mw = 500,000 to 800,000, refractive index = 1.68) ... 1 g Hollow particles (particle diameter 250 μm, inner pore diameter 50 μm) 1 g Trichloro-s-triazine 0.07 g Ketocoumarin dye (manufactured by Kodak Co., λ _max = 460 nm) 0.003 g in 14.51 g chlorobenzene Then, a hollow particle dispersion liquid was added to obtain a photosensitive liquid, and a recording medium having a thickness of 7 μm was similarly obtained.

Then, a polyvinyl alcohol film was provided on the surface of the recording medium in the same manner as in Example 1, and then an argon laser [488 nm] light was used to obtain an exposure energy of 200 mJ / cm ² using the optical system shown in FIG. It was irradiated so that

After the exposure, the residual monomer was polymerized by irradiating with ultraviolet rays at 500 mJ / cm ² .

The diffraction efficiency of the obtained hologram was 70%,
The reproduction wavelength was 514 nm, the haze was about 1%, and the diffraction grating was transparent and had high diffraction efficiency.

[0102]

Example 3 Poly-N-vinylcarbazole (manufactured by Anan Fragrance Industry Co., Ltd., Tubicor 210, Mw = 500,000 to 800,000, refractive index = 1.68) ... 1 g Tribromophenoxyethyl acrylate (Daiichi Kogyo Seiyaku Co., Ltd., New Frontier BR-31) ... 0.2 g-Trichloro-s-triazine (Midori Kagaku Co., Ltd., TAZ-101) ... 0.07 g-Hollow particles ( 0.8 g was charged into 41.4 g of chlorobenzene to obtain a hollow particle dispersion liquid, which was used as a photosensitive liquid.

This photosensitive solution was applied to a PET film
-7W, 50μm thick) on a spinner (500r
pm / 5 sec and 1000 rpm / 20 sec) and then dried for 3 minutes with a drier and then exposed to ultraviolet rays (F
USION JAPAN K. K. Made) 100 mJ /
cm ^{2 was} irradiated to form a low refractive index film having a thickness of 0.367 μm.

Then, poly-N was formed on the surface of the low refractive index film.
-Vinylcarbazole (Tsubicol 210, manufactured by Anan Fragrance Industry Co., Ltd., Mw = 500,000 to 800,000, refractive index = 1.6)
5% by weight chlorobenzene solution of 8) was applied with a spinner (500 rpm / 5 sec and 1000 rpm / 20 s).
ec) and then dried for 3 minutes with a drier to give a film thickness of 0.3
The layers were laminated with a thickness of 67 μm to provide a high refractive index film.

The low refractive index film and the high refractive index film were laminated 15 times to obtain the second diffraction grating of the present invention.

The diffraction efficiency of the obtained hologram is 90%.
Then, when I put this film on the window glass, it was 1100
Reflecting the infrared rays of sunlight in the vicinity of nm, a decrease in temperature near the window glass was observed.

[0107]

Comparative Example 1 As the photosensitive liquid in Example 1, the photosensitive liquid was prepared by removing the hollow particles, and a recording medium was prepared in the same manner as in Example 1, and then similarly exposed.

After the exposure, the recording medium was dipped in methyl isobutyl ketone to swell mainly in the bright part of the interference fringes of the film, and the monomer (oligomer) in the dark part was dissolved in the developing solution and then dipped in heptane. The swelling liquid in the monomer elution region was replaced with heptane and dried to form a hologram.

The voids in the obtained hologram are TE
In the M photograph observation, even the smallest one is several 100 nm,
The diffraction efficiency of the hologram was 90%, but the haze was 3%, and only an opaque film was obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a Lippmann type exposure optical system for exposing a mirror hologram that reflects a specific visible ray.

FIG. 2 is a schematic diagram of a Denishuke type exposure optical system for exposing a mirror hologram that reflects a specific visible ray.

FIG. 3 is a schematic diagram of a Lippmann type exposure optical system for exposing a mirror hologram that reflects a specific infrared ray.

FIG. 4 is a schematic diagram of a Denishuke type exposure optical system for exposing a mirror hologram that reflects a specific infrared ray.

[Explanation of symbols]

1 ... Argon laser, 2 ... Half mirror, 3 ... Mirror, 4 ... Special filter, 5 ... Record carrier, 6 ... Lens, 7 ... Matching solution, 8 ... Glass block

Claims (12)

[Claims] 1. A hologram comprising a high-refractive index layer and a low-refractive index layer, wherein the high-refractive index layer and the low-refractive index layer are formed by sparse and dense hollow particles, and the maximum cutoff of the hollow particles. A diffraction grating characterized in that the diameter of the area is not more than the wavelength of visible light. 2. The diffraction grating according to claim 1, wherein the low-refractive-index layer is a portion where interference lights are weakened during hologram recording. 3. The diffraction grating according to claim 1, wherein the low-refractive-index layer is a portion where interference lights during hologram recording are mutually strengthened. 4. A multilayer film in which a high refractive index film and a low refractive index film are laminated, wherein the low refractive index film contains hollow particles, and the diameter of the maximum cross-sectional area of the hollow particles is the visible light wavelength. A diffraction grating characterized in that: 5. The diffraction grating according to claim 4, wherein the high refractive index film is laminated on the low refractive index film by coating. 6. The diffraction grating according to claim 4, wherein the high refractive index film is laminated on the low refractive index film by extrusion molding. 7. The diffraction grating according to claim 1, wherein the diffraction grating pitch is 200 to 700 nm. 8. The hollow particle has a flat spherical shape, and its minor axis direction is present in the same direction as the film thickness direction of the diffraction grating. Diffraction grating. 9. A recording medium composed of hollow particles, a photopolymerizable monomer, and a photopolymerization initiator is irradiated with laser light so as to form interference fringes, and the photopolymerizable monomer in the portion where the interference lights are intensified is polymerized. After diffusing and moving the hollow particles to the part where the interference light weakens, post-exposure is performed to cure the part where the interference light weakens, and the part where the interference light strengthens is a high refractive index layer,
A method of forming a diffraction grating, characterized in that a portion where the interference light is weakened is a low refractive index layer. 10. A recording medium comprising hollow particles, a photopolymerizable monomer and a photopolymerization initiator, wherein the hollow particles are hollow particles having a photopolymerizable functional group on the outside thereof, to form interference fringes with laser light. As such, the interference light is polymerized with the photopolymerizable monomer in the portion where the interference light strengthens and the photopolymerizable functional group in the hollow particles to diffuse and move the hollow particles to the portion where the interference light strengthens, and then post-exposed, A method of forming a diffraction grating, characterized in that a photopolymerizable monomer in a portion where interference light is weakened is cured, a portion where interference light is strengthened is a low refractive index layer, and a portion where interference light is weakened is a high refractive index layer. . 11. A recording medium comprising hollow particles, a binder polymer and a photopolymerization initiator, the hollow particles being hollow particles having a photopolymerizable functional group on the outside thereof, is irradiated with laser light so as to form interference fringes. Then, the photopolymerizable functional groups in the hollow particles are polymerized with each other in the portion where the interference light is strengthened, and the hollow particles are diffused and moved to the portion where the interference light strengthens,
A method of forming a diffraction grating, characterized in that a portion where interference light is strengthened is a low refractive index layer and a portion where interference light is weakened is a high refractive index layer. 12. A hollow particle having a filling material therein, and after forming the diffraction grating, the filling material in the hollow particle is selectively removed to form a hollow particle.
11. The method for forming a diffraction grating according to any one of 11.