JPH05341702A - Hologram recording material - Google Patents

Abstract

PURPOSE:To provide the material of a new type having high diffraction efficiency, high light transmittance and excellent moisture resistance. CONSTITUTION:This hologram recording material is constituted by using a resin contg. a carbazole ring in its unit structure as a binder polymer and uniformly dispersing polymerizable monomers of a phosphazene system and acrylic system having the refractive index lower than the refractive index of this binder polymer, a photopolymn. initiator and a sensitizer into the binder polymer. The polymerizable monomer of the phosphazene system and the polymerizable monomer of the acrylic system of a photoirradiated part are polymerized by photoirradiation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to improvements in hologram recording materials. A hologram is a technique in which interference patterns of a plurality of coherent lights are recorded, and one light beam at the time of recording is applied to reproduce the other light beam at the time of recording.

Holograms initially developed as stereoscopic photography technology, but since the functions of conventional optical components such as lenses, prisms, and mirrors can be integrated into hologram films, recently new optical elements such as bar code readers and laser printers have been developed. It can be applied to laser scanning systems and combiners for head-up displays.

Here, the requirements for the hologram recording material are that it can be recorded by a visible light laser, that it has high sensitivity, that it has high diffraction efficiency, that it is colorless and transparent and that it has high light transmittance, and that it has excellent environmental resistance. That there is no crack in the film.

[0004]

2. Description of the Related Art As a light-sensitive material for hologram recording, a silver salt used in an ordinary photographic material, which has been subjected to a bleaching treatment, or dichromated gelatin is used.

These silver salts and dichromated gelatin have high sensitivity over the entire visible light range. Since the gelatin film is used as a binder, the moisture resistance, heat resistance, light resistance, etc. There is a problem of low environmental resistance.

In order to solve this problem, a polymer hologram recording material has been proposed in which a polymer containing a carbazole ring is used as a main component and an organic halogen compound is used as a photoreaction initiator. (For example, Japanese Examined Patent Publication No. 55-31453 etc.) Here, an organic halogen compound is used as a photoreaction initiator, but an organic iodine compound such as carbon tetraiodide (CI ₄ ) is used.
When gel is used, gelation easily occurs, and iodoform (C
When HI ₃ ) is used, there is a problem that the photosensitive region becomes the ultraviolet region and the sensitivity to visible light is low.

Further, when an organic iodine compound is used, decomposition occurs as the light irradiation amount increases and a green color is exhibited, which causes a problem that the transparency of the hologram decreases.

[0008]

A recording material containing a polymer having a carbazole ring, such as polyvinylcarbazole, as a main component and an organic halogen compound as a photoreaction initiator is a hologram recording material having excellent environmental resistance. There is a problem in terms of reliability due to gelation or coloring.

Therefore, it is an object to put into practical use a hologram recording material that does not have such drawbacks.

[0010]

[Means for Solving the Problems] The above-mentioned problem is that a resin containing a carbazole ring in a unit structure is used as a binder polymer, and a phosphazene-based or acrylic-based polymerizable monomer having a refractive index lower than that of the binder polymer and a photopolymerization initiator are used. A sensitizer is uniformly dispersed, and by using a hologram recording material characterized by polymerizing the phosphazene-based polymerizable monomer and the acrylic-based polymerizable monomer in the light-irradiated portion by light irradiation. Can be resolved.

[0011]

In the conventional carbazole-based hologram recording material, cross-linking is caused by light irradiation, and the density of the cross-linking is increased, so that the refractive index is increased as compared with the unexposed portion, and a difference in refractive index is generated between the two. It is believed that the hologram is formed by utilizing the.

However, it is difficult to obtain such a large difference in refractive index with this method. Therefore, the inventor previously found that a polymer containing a carbazole ring in the unit structure had a refractive index of 1.65 to
As high as 1.70, it is a material with excellent light transmission and also has excellent moisture resistance, so this is used as a binder polymer,
A holographic recording material, in which a phosphazene-based polymerizable monomer having a low refractive index and good light transmittance, a photopolymerization initiator and a sensitizer are dispersed, is proposed and filed. (Japanese Patent Application No. 03-3
29361, filed on Dec. 13, 1991) This hologram recording material is characterized by the fact that when irradiated with light, the monomer in the irradiated area polymerizes to form a polymer with a low refractive index, and a mixture with a polymer containing a carbazole ring in its unit structure is used. By making it, a hologram having a larger difference in refractive index than before can be realized.

The reason why the addition of the sensitizer is necessary is that a visible light laser such as an argon (Ar) laser (having a wavelength of 488 nm) is used as a light source for forming a hologram.
This is because it is necessary to expose and polymerize with visible light.

As a result of selecting a monomer satisfying the above conditions, the inventor has found that the phosphazene type monomer has a refractive index of 1.5.
It was used as a result of the fact that it was a material having a low degree of compatibility and good compatibility with the binder polymer and was a suitable material.

Although the phosphazene compound is known as a coating material having excellent heat resistance and light transmittance,
Conventional applications are coating agents for wood, plastics, cloth, etc., and their use in combination with organic compounds is not known. (For example, JP-A-63-241075) Now, as a result of further research, the inventor mainly made a dispersion of a mixture of a phosphazene type monomer and an acrylic type monomer in a binder polymer containing a carbazole ring in its unit structure. It was found that when the hologram recording material was constituted as a component, the photoreactivity was improved as compared with the case where the phosphazene monomer alone was used.

That is, it has been found that the interference exposure forms a copolymer of a phosphazene type monomer and an acrylic type monomer in the exposed portion or a mixture of polymers to form a higher refractive index difference.

As a specific processing method, a hologram is obtained by decolorizing to remove the photopolymerization initiator and sensitizer, and then developing to remove unreacted phosphazene monomer and acrylic monomer. be able to.

As the phosphazene-based monomer, it is preferable to use hexachlorocyclotriphosphazene represented by the following general formula (1) in which the chlorine moiety is substituted with an acrylate group, a methacrylate group, a vinyl group, an allyl group or the like.

[0019]

[Chemical 1] As the acrylic monomer, it is effective to use a polyfunctional acrylate monomer such as pentaerythritol triacrylate, trimethylolpropane triacrylate, isocyanuric acid ethylene oxide triacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. ..

Next, as a result of investigating a photopolymerization initiator capable of photopolymerizing a mixture of a phosphazene type monomer and an acrylic type monomer, benzoin ether type well known as a compound capable of generating a radical by light, It was found that ketal-based, acetophenone-based, benzophenone-based, thioxanthone-based initiators, organic peroxides, N-phenylglycine, triazine-based compounds, and allene iron complexes are effective.

Specific examples of the benzoin ether type include isopropyl benzoin ether and isobutyl benzoin ether. Also, as a ketal system
1-hydroxycyclohexyl phenyl ketone and benzyl dimethyl ketal can be mentioned.

As the acetophenone type, 2-hydroxy-2-methyl-propiophenone, 4-isopropyl-2
-Hydroxy-2-methyl-propiophenone. Further, as a benzophenone type, benzophenone, O
Examples of the thioxanthone-based compound include 2-methylthioxanthone and 2-chlorothioxanthone.

Further, as the organic peroxide, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxydicarbonate and the like are effective.

The triazine-based compound is 2,4,6-
Tris (trichlomethyl) -1,3,5-triazine and 2,4-Bis (trichl
Compounds having a 1,3,5-triazine structure and at least one trichloromethyl group in the molecule such as omethyl) -6-phenyl-1,3,5-triazine are effective.

As the allene iron complex, (η ⁶ -benzene) (η ⁵ -cyclopentagenyl) iron (11) hexafluorophosphate, (η ⁶ -pyrene) (η ⁵ -cyclopentagenyl) iron (11) Hexafluoroantimonate and (η ⁶ -naphthalene) (η ⁵ -cyclopentagenyl) iron (11) hexafluorophosphate are effective. Further, these radical generators alone do not absorb visible light, and it is not possible to record a hologram with Ar laser light that is visible light, but by adding a sensitizer as described above. It can be made highly sensitive to laser light.

Here, the dye acting as a sensitizer is 4-
(Dicyanomethylene) -2-methyl-6- (p-dimethylaminostyr
yl) -4H-pyran and aromatic thiopyrylium compounds and 3- (2´-B
enzothiazolyl) -7-N, N-diethylaminocoumarin, 3,3´-C
arbonylbis (7-diethylaminocoumarin), 3- (2´-Benzimi
dazolyl) -7-N, N-diethylaminocoumarin, etc., a dye composed of a compound having a coumarin structure represented by the following general formula (2) in the molecule,

[0027]

[Chemical 2] 2,6-Bis (p-dimethylaminobenzylidene) cyclohexanone, 4
-t-Butyl-2,6-bis (4´-dimethyminobenzylidene) cycloh
2,6-Bis shown in the following general formula (3), such as exanone.
A dye composed of a compound having a (benzylidene) cyclohexanone structure in the molecule,

[0028]

[Chemical 3] Like 2 ', 7'-Dichlorofluorescein, Fluorescein,
It was found that a dye composed of a compound having a Fluorescein structure represented by the following general formula (4) in the molecule is effective.

[0029]

[Chemical 4]

[0030]

Examples Example 1: Binder polymer: Poly-N-vinylcarbazole: 10.0 g Phosphazene monomer: 3PNC-HEMA6 substitution product: 3.0 g (2-hydroxyethyl methacrylate 6 substitution product) Acrylic monomer : Isocyanuric acid EO modified (n = 3) triacrylate 3.0g Photoinitiator: 3,3 ', 4,4'-Tetra- (t-butylperoxycarbonyl) -benzo phenone ・ ・ ・ ・ ・1.0g Sensitizer: 4- (Dicyanomethylene) -2-methyl-6- (p-dimethylamino styryl) -4H-pyran: 0.2g Solvent: Monochlorobenzene: 40.0g Tetrahydrofuran:・ ・ ・ 40.0 g The photosensitive solution having the composition above was spin-coated on a glass substrate having a size of 70 × 70 mm and a thickness of 1 mm to prepare a hologram recording dry plate having a thickness of 5 μm after drying.

Using this dry plate, Ar laser light (wavelength 488 nm)
Was irradiated from both sides, and a transmission hologram was recorded with an exposure amount of 48 mJ / cm ² using a two-beam interference exposure optical system. next,
After removing the photopolymerization initiator and sensitizer by immersing them in a tetrahydrofuran / xylene / isopropanol mixed solution for 3 minutes (decolorization treatment), leave them in an atmosphere with a humidity of less than 20% for 2 hours, and then with a humidity of 20%. In an atmosphere of less than 1, first, it was dipped in a xylene / toluene mixed solution for 60 seconds, pulled up, slowly dipped in n-pentane, and after 20 seconds, pulled up and developed.

As a result, a transparent hologram without defects such as cracks could be formed. Next, copy this hologram to He-N
When reproduced with e laser light (wavelength 633 nm), the transmission diffraction efficiency was 75%.

When the light transmittance was measured with He-Ne laser light, a value of 94% was obtained. In order to examine the humidity resistance, the sample was left in a constant temperature bath at 70 ° C and 95% RH, but no decrease in diffraction efficiency or light transmittance was observed even after 10 days. Example 2: (Example in which the photopolymerization initiator was changed in Example 1) 3,3 ′, 4,4′-Tet as the photopolymerization initiator in Example 1
A hologram was prepared in exactly the same manner except that the following seven types of photopolymerization initiators were used instead of ra- (t-butylperoxycarbonyl) -benzophenone, and the diffraction efficiency was measured to give the following value. It was No. 1 (isopropyl benzoin ether, 1.20 g added) ・ ・ ・ Diffraction efficiency 61% No. 2 (benzyl dimethytyl ketal, 1.50 g added) ・ ・ ・ 〃65% No. 3 (2-hydroxy-2- Methyl propiophenone, 1.60 g added ・ 〃 67% No. 4 (benzoyl peroxide, 1.00 g added) ・ ・ ・ ・ ・ 72% No. 5 (2,4,6-Tris (trichloromethyl) -1, 3,5-triazine, 1.20 g added) 〃 65% No. 6 (η ⁶ -benzene) (η ⁵ -cyclopentaenyl) iron (11) hexafluorophosphate, 1.50 g added)・ ・ ・ ・ ・ ・ ・ ・ Diffraction efficiency 60% No. 7 (with addition of 1.50 g of N-phenylglycine) ・ ・ ・ ・ ・ 62%, which was a good result. Example 3: (Example in which the sensitizer was changed in Example 1) In Example 1, 4- (Dicyanomethyl) was used as the sensitizer.
A hologram was prepared in the same manner except that the following four types of sensitizers were used instead of ene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran, and the diffraction efficiency was measured.
I got the following values. No. 1 [3- (2'-Benzothiazolyl) -7-N, N-diethylaminocoumarin, 0.15g added] ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Diffraction efficiency 73% No. 2 [4-t-Butyl- 2,6-bis (4'-dimethylaminobenzylidene) cyclohexanone, 0.2g added] ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Diffraction efficiency 72% No. 3 (2 ', 7'-Dichlorofluorescein, 0.15g 64% No. 4 (4-butoxyphenyl-2,6-diphenylthiopyrylium perchlorate, 0.25g added) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Diffraction efficiency We were able to obtain a good result of 71%. Example 4: (Example in which acrylic monomer was changed in Example 1) Except for using the following three types of acrylic monomers instead of using isocyanuric acid EO-modified (n = 3) triacrylate in Example 1 When holograms were formed in the same manner and the diffraction efficiency was measured, the following values could be obtained. No. 1 (Pentaerythritol acrylate, 3.0 g added) ・ ・ Diffraction efficiency 73% No. 2 (Trimethylolpropane triacrylate, 4.0 g added) ・ ・ ・ ・ ・ ・ ・ Diffraction efficiency 71% No. 3 (Di Pentaerythritol hexaacrylate, 3.0 g added) ・ ・ ・ ・ ・ ・ Diffraction efficiency of 68% and good results were obtained.

[0034]

EFFECTS OF THE INVENTION The hologram recording material according to the present invention is chemically stable and excellent in moisture resistance as compared with the conventional hologram recording materials, and the use of this material provides excellent sensitivity and light transmittance. A hologram can be obtained.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03F 7/028 7/033

Claims (4)

[Claims] 1. A binder polymer is a resin containing a carbazole ring in its unit structure, and a phosphazene-based or acrylic-based polymerizable monomer having a lower refractive index than the binder polymer, a photopolymerization initiator, and a sensitizer are uniformly dispersed. And a phosphazene-based polymerizable monomer and an acrylic-based polymerizable monomer in the light irradiation portion are polymerized by light irradiation. 2. The hologram recording material according to claim 1, wherein the polymer containing a carbazole ring in its unit structure is polyvinylcarbazole, halogenated polyvinylcarbazole or vinylcarbazole copolymer. 3. The phosphazene-based polymerizable monomer is a compound in which the chlorine moiety of hexachlorocyclotriphosphazene is substituted with an acrylate group, a methacrylate group, a vinyl group, or an allyl group.
The hologram recording material described. 4. The hologram recording material according to claim 1, wherein the acrylic polymerizable monomer is a polyfunctional monomer.