JP3491509B2 - Hologram recording material - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to 350-420n
High sensitivity to m light, especially argon laser light and krypton laser light, excellent weather resistance, heat resistance and storage stability, and excellent hologram characteristic values such as resolution, diffraction efficiency and transparency. The present invention relates to a hologram recording material used for forming a volume phase hologram.

[0002]

2. Description of the Related Art Conventionally, since holograms can reproduce three-dimensional stereoscopic images, they have been used for books, covers for magazines, displays for POPs, gifts, etc. because of their excellent design and decorative effects. . Since holograms can be said to be equivalent to the recording of information in submicron units, they are also used for counterfeit prevention marks such as securities and credit cards.

Particularly, the volume phase hologram modulates the phase without absorbing the light beam passing through the image by forming spatial interference fringes having different refractive indexes in the hologram recording medium, not by optical absorption. Therefore, in recent years, application to a hologram optical element (hereinafter, referred to as HOE) represented by a head-up display (HUD) mounted on an automobile is expected in addition to a display application.

By the way, the volume phase hologram recording material constituting the volume phase hologram is required to be highly sensitive to a laser beam having a visible oscillation wavelength and exhibit a high resolution. Further, when actually used for forming a hologram, it is required that characteristics such as diffraction efficiency of hologram, wavelength reproducibility of reproduced light, band width (half-value width of reproduced light peak) and the like are suitable for the purpose. In particular, the hologram recording material of the reflection flag hologram for HOE has a diffraction efficiency of 90% or more at a spatial frequency of 5000 to 6000 lines / mm, and a half value width (band width) of the peak of reproduced light of 20 to 30.
nm, the peak wavelength of the reproduction wavelength is preferably within 5 nm from the photographing wavelength. On the other hand, the hologram recording material of the transmission hologram has a spatial frequency of 800 to 2000.
The number of lines / mm may be sufficient, but the transmittance of the hologram is preferably 80% or more in the visible region, and even if the transmittance is 80% or more, coloring of the hologram with a sensitizing dye or the like causes a problem in appearance. Further, these holograms are also required to have excellent storage stability for a long period of time.

Hitherto, as a recording material for such a volume phase hologram, a bleached silver salt and a dichromate gelatin type photosensitive material have been generally used. This dichromated gelatin-based photosensitive material is most widely used for recording volume phase holograms because of its high diffraction efficiency and low noise characteristics, but this photosensitive material has a short shelf life,
Problems that must be adjusted each time a hologram is made, and problems that hologram reproducibility is poor due to deformation of the hologram during the swelling and shrinking process of gelatin that is required when making a hologram by wet development It also has points. Further, the silver salt sensitive material requires complicated processing after recording, and is not a photosensitive material which is satisfactory from the viewpoint of stability and workability. Furthermore, all of these above-mentioned light-sensitive materials have a problem that they are inferior in environmental resistance characteristics such as moisture resistance and weather resistance.

To solve these problems, a solvent-soluble, cation-polymerizable ethylene oxide ring is used as a material having excellent environmental resistance and having the characteristics that a hologram recording material should have, such as high resolution and high diffraction efficiency. A hologram recording material comprising a thermosetting resin having at least one in the structural unit and a radically polymerizable ethylenic monomer (JP-A-8-1676, JP-A-8-1677,
JP-A-8-1678 and JP-A-8-1679).

[0007]

However, all of these hologram recording materials are sensitive to the visible region, in particular, argon laser light (488 nm) and laser light having a longer wavelength than that of the laser light. For this purpose, various sensitizing dyes are added. In the case of a reflection type hologram, it becomes equivalent to a mirror that reflects only light in the vicinity of a specific wavelength (generally a recording wavelength) according to black reflection, so that its complementary color appears, and coloring of the hologram cannot be avoided unless it is made full color. In the case of a transmission hologram where the coloring due to the dye remaining in the hologram is somewhat inconspicuous, the effect of the remaining dye is large even if the transmittance in the visible region is around 80%, and it is necessary that the appearance be colorless and transparent. Will be a problem. Therefore, the present invention is a volume phase which is excellent in weather resistance, heat resistance, chemical stability, and storage stability, and has high resolution, high diffraction efficiency, high transparency, and reproduction wavelength reproducibility by dry processing. An object of the present invention is to provide a hologram recording material capable of forming a type hologram.

[0008]

The present invention has been made to solve the above problems, and the invention according to claim 1 is
(A) Thermosetting resin having at least one solvent-soluble, cationically polymerizable ethylene oxide ring in a structural unit and having a melting point of 60 ° C. or higher, (B) radically polymerizable ethylenic monomer, (C) chemical action A photoinitiator that activates radical and cationic polymerization upon exposure to radiation,
In a hologram recording material comprising (D) (C) a sensitizing dye that sensitizes a photoinitiator, (D) the sensitizing dye has an absorption wavelength of 350 to 420 nm, and (C) the photoinitiator can be spectrally sensitized. A hologram recording material comprising a compound.

According to a second aspect of the invention, in the hologram recording material according to the first aspect, (A) the thermosetting resin is
It is characterized by being represented by the general formula (1).

[0010]

[Chemical 4]

(In the formula, R ₁ and R ₂ are each a hydrogen atom,
Alternatively, it represents a functional group selected from a methyl group, an ethyl group and a trifluoro group, and n = 1 to 20. )

According to a third aspect of the invention, in the hologram recording material according to the first aspect, the thermosetting resin (A) is
It is characterized by being represented by the general formula (2).

[0013]

[Chemical 5]

(In the formula, n = 1 to 20)

According to a fourth aspect of the invention, in the hologram recording material according to the first aspect, (A) the thermosetting resin is
It is represented by the general formula (3) and has an epoxy equivalent of 400 to 6000.

[0016]

[Chemical 6]

According to a fifth aspect of the present invention, in the hologram recording material according to the first aspect, the photoinitiator is any one of trihalogenomethyl-substituted s-triazine and diaryliodonium salt.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
FIG. 1 is a schematic diagram illustrating the configuration of a hologram recording medium 1 made of the hologram recording material of the present invention, and FIG. 2 is a schematic explanatory diagram illustrating an optical system for hologram imaging.

The component (A) constituting the hologram layer of the hologram recording material of the present invention is a solvent-soluble thermosetting resin having at least one cationically polymerizable ethylene oxide ring in its structural unit, such as bisphenol A, Bisphenol AD, bisphenol B, bisphenol AF, bisphenol S, brominated bisphenol A, novolac, o-cresol novolac, p-alkylphenol novolac, hydrogenated bisphenol A,
The following chemical formula is generated by the condensation reaction of various phenol compounds such as hydrogenated bisphenol AD, hydrogenated bisphenol B, hydrogenated bisphenol AF, hydrogenated bisphenol S, and hydrogenated brominated bisphenol A with epichlorohydrin. An epoxy compound may be used. However, it is not limited to these.

[0020]

[Chemical 7]

(Wherein R ₁ and R ₂ are each a hydrogen atom,
Alternatively, it represents a functional group selected from a methyl group, an ethyl group and a trifluoro group, and n = 1 to 20. )

[0022]

[Chemical 8]

(In the formula, n = 1 to 20)

[0024]

[Chemical 9]

The thermosetting resin as the component (A) preferably has a molecular weight in the range of 900 to 6000. When the molecular weight is smaller than this range, the film-forming property is deteriorated and uniform coating is difficult. When the molecular weight is larger than this range, it is generally difficult to synthesize. Further, this thermosetting resin preferably has an epoxy equivalent of 400 to 6700, and there is a problem that good cationic polymerization does not proceed outside this range.

The radical-polymerizable aliphatic monomer of the component (B) has at least one ethylenically unsaturated bond in the structural unit, and is a polyfunctional monomer other than the monofunctional vinyl monomer. It contains a functional vinyl monomer and may be a mixture thereof. Further, those having a large difference in refractive index from the thermosetting resin of the component (A) are preferable, and when the thermosetting resin of the component (A) is aromatic, an aliphatic monomer is preferable. In particular,
(Meth) acrylic acid, itaconic acid, maleic acid, (meth) acrylamide, diacetone acrylamide, 2-
High-boiling-point vinyl monomers such as hydroxyethyl (meth) acrylate, and aliphatic polyhydroxy compounds such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, neopentyl glycol, 1,3-
Propanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,1
Examples thereof include di- or poly (meth) acrylic acid esters such as 0-decanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol and mannitol. However, it is not limited to these.

Further, the chemical action of the above component (C) is exposed to radiation.
Photolysis that activates radical and cationic polymerization when exposed to light
Examples of the initiator include J.I. Photochem. Sci. Te
chnol. , 2,283 (1987). Described in
There are compounds such as iron arene complexes and trihalogenomes.
Cyl-substituted s-triazine, sulfonium salt, diazoni
Umium salt, phosphonium salt, selenonium salt, arso
Examples thereof include a aluminum salt and an iodonium salt. This iodine
As a sodium salt, Macromolecules,1
0, 1307 (1977). The compound described in
For example, diphenyliodonium, ditolyl iododon
Um, phenyl (p-anisyl) iodonium, bis
(M-nitrophenyl) iodonium, bis (p-te
rt-Butylphenyl) iodonium, bis (p-chloro)
Chloride of iodonium such as (rophenyl) iodonium
, Bromide, borofluoride, hexafluoro
Phosphate salt, hexafluoroarsenate salt, fragrance
Examples thereof include group sulfonates. In addition, the above
If it satisfies the characteristics, it is not limited to these
There is no.

Further, the sensitizing dye of the component (D) of the present invention has absorption at a wavelength of 350 to 420 nm, and (C)
It is an organic dye compound capable of spectrally sensitizing photoinitiators. In addition, "Dye Handbook" (Shin Okawara et al., Kodansha 1
986), "Chemistry of Functional Dyes" (Nobu Okawara et al., CMC 1986), "Special Functional Materials" (Tadasaburo Ikemori et al., CMC 1986), and use of dyes and sensitizers. You can However, it is not limited to these. Further, if necessary, these dyes and sensitizers can be used in combination of two or more kinds at any ratio. Specifically, butyl p- (N, N-dimethylamino) benzoate, ethyl p- (N, N-dimethylamino) benzoate, ethyl o- (N, N-dimethylamino) benzoate, 2-chloro Thioxanthone, 2,
4-diethylthioxanthone, bis (N, N-dimethylamino) benzophenone (Michler's ketone), bis (N, N-dimethylamino) benzophenone, thioflavin T, diethyl 2- [p- (N-dimethylaminophenyl) enitel] malonate , 2-cyano-3-indolylethyl acrylate, 2-benzoyl-3-indolyl-2-propenenitrile and the like dialkylaminobenzylidene compounds. However, it is not limited to these.

The hologram recording material having the above composition is obtained by mixing 20 to 200 parts by weight of the (B) ethylenic monomer with 100 parts by weight of the (A) thermosetting resin, and preferably , 30 to 100 parts by weight. The amount of the (C) photoinitiator is the same as that of the (A).
The amount is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the thermosetting resin. Further, the amount of the (D) sensitizing dye is 100% of the (A) thermosetting resin.
0.1 to 5 parts by weight, preferably 0.2
To 0.5 parts by weight. Since the amount used is limited by the optical density of the hologram recording layer to be formed and its thickness, it is preferable to use the optical density within a range not exceeding 2. If it deviates from this range, it becomes difficult to obtain a high diffraction efficiency and the sensitivity characteristic deteriorates.

Thus, the photosensitive liquid of the hologram recording material obtained by appropriately selecting each of these components and mixing them at an arbitrary ratio is used as a bar coater, applicator, doctor blade, spin coater, roll coater, die coater,
Using known coating means such as comma coater, comma reverse coater, gravure coater, microgravure coater, lip coater, lip reverse coater, fountain reverse coater, glass plate, polycarbonate, polymethylmethacrylate, polyethylene terephthalate, polymethylpentene, A hologram layer 3 is formed by coating the base material 2 made of various resins such as cellulose triacetate and polyester film in a film form, and further, a protective layer 4 is attached if necessary, laminating by an extruder or the like, coating of a solution. The hologram recording medium 1 shown in FIG. 1 is manufactured by forming the hologram recording medium 1.

Although it is possible to dilute the hologram recording material with an appropriate solvent when applying the hologram layer 3, it is necessary to dry the hologram recording material after applying it to the base material 2, and as described above, at the time of photographing. It is desirable to adjust the transmittance of the irradiation light to 1% or more. Specifically, as the solvent, dichloromethane, chloroform, acetone, 2-
Butanone, cyclohexanone, ethyl acetate, 2-
Methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethoxyethyl acetate, 2
-Butoxyethyl acetate, 2-methoxyethyl ether, 2-ethoxyethyl ether, 2- (2-ethoxyethoxy) ethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethyl acetate, 2- (2-Butoxyethoxy) ethyl acetate, tetrahydrofuran, 1,4-dioxane and the like can be mentioned.

The protective layer 4 is a non-stretched film (film thickness: 50) made of, for example, polyvinyl alcohol resin.
〜100μm) ・ Biaxially stretched film (film thickness: 12-25
μm), a polyvinyl alcohol resin, a coating solution containing a polyvinyl alcohol resin as a main component, and dried to form a coating film, or on any film-shaped support material such as polyethylene terephthalate, polymethacrylate, cellulose triacetate, polypropylene, or polyethylene. Polyvinyl alcohol resin aqueous solution, for example, saponification degree 87-89%, medium degree of polymerization (viscosity of 4% aqueous solution at 20 ° C. is 20-30 cp.
The polyvinyl alcohol resin of s) is preferable, and 5 to
A 10% aqueous solution is especially preferred. Using this, a laminated material formed of polyvinyl alcohol resin (PVA) with a dry film thickness of 0.5 to 5 μm may be provided.

If desired, various additives such as known binders, plasticizers, thermal polymerization inhibitors, chain transfer agents and antioxidants may be added to the hologram recording material constituting the hologram layer 3 of the present invention. Good.

Further, when producing a hologram by an optical duplication method, the hologram recording medium 1 may use an intermediate liquid between the hologram master and the mirror in order to improve the adhesion thereof. Specifically, it is preferable that the hologram master and the hologram recording medium 1 (hologram recording material) do not invade and have a relatively high boiling point with a refractive index of about 1.4 to 1.6. Examples thereof include saturated hydrocarbons such as n-heptane, n-octane, isooctane, n-nonane, and n-decane, and isoper, which is a mixture thereof, or aromatic hydrocarbons such as toluene and xylene, but are not limited thereto. Not something.

The process of holographically exposing the hologram recording medium 1 using the hologram recording material to form a latent image is shown in FIG. The laser beam 6 oscillated from 5 enters the hologram recording medium 1 through the mirror 7, the beam splitter 10, the lens 8 and the spatial filter 9, and the light transmitted through the hologram recording medium 1 is a hologram master or a mirror. Then, the hologram image is recorded by being reflected by and entering the hologram recording medium 1 again to form interference fringes. Further, in the present invention, after the hologram is photographed by exposure, the fixing process is performed by a dry process.

When a hologram image is recorded on the hologram recording medium 1, laser irradiation is applied to the hologram layer 3 in accordance with a desired image, so that a portion of the laser irradiation portion having a strong optical interference action is (A). When the (B) radically polymerizable ethylenic monomer uniformly dispersed in the thermosetting resin is exposed to laser (laser interference light) irradiation, (C) the photopolymerization initiator acts to polymerize and polymerize. Therefore, the (B) radically polymerizable ethylenic monomer around it moves. Therefore, the concentration of the (B) radical-polymerizable aliphatic monomer is high at the laser-irradiated portion where the optical interference is strong, and the (B) radical-polymerizable ethylenic monomer concentration is weak at the portion where the light interference action is weak. Is decreased, the refractive index modulation due to the difference in the refractive index occurs due to the difference in density between the portion of the hologram recording medium 1 having strong optical interference and the portion having weak optical interference,
Thereby, hologram image recording is performed.
Here, since the (D) sensitizing dye has an absorption wavelength of 350 to 420 nm and (C) is a compound capable of spectrally sensitizing the photoinitiator, the hologram recording material is colored because it does not include the visible light wavelength range. It is not affected by the dye remaining after the hologram is formed, and the appearance is colorless and transparent, and has high transparency. Further, the protective layer 4 laminated on the hologram layer 3 of the holographic recording medium 1 functions as an oxygen blocking film when the ethylenic monomer is polymerized by radical species generated by hologram exposure, and functions as a hologram master or a mirror. In order to improve the adhesion with the hologram recording medium 1 of the invention, the hologram layer 3 is removed from the intermediate liquid.
Function as a protective film that protects the hologram layer 3
Can have high diffraction efficiency. Furthermore, by the whole surface exposure treatment of ultraviolet rays and the heat treatment after the hologram exposure,
The residual (B) monomer is fixed by polymerization, and the thermosetting resin (A) as a support has a crosslinked structure due to cationic polymerization, so that the hologram recording medium 1 has weather resistance, heat resistance, and chemical stability. The property is improved.

In the exposure process of the interference pattern,
As a light source suitable for the hologram recording material of the present invention, a helium-cadmium laser, an argon laser, a krypton laser, or the like can be used, but the light source is not limited thereto.

Further, the hologram recording material of the present invention is more excellent in reproducibility of the peak wavelength of reproduction light and its bandwidth than the conventional hologram recording material, and further has transparency in the visible range, and Since it has excellent environmental resistance and can be mass-produced, it can be applied to a hologram optical element (HOE).

[0039]

EXAMPLES The present invention will be described in detail below based on specific examples. <Example 1-4> 100 parts by weight of bisphenol epoxy resin (trade name "Epicoat 1007" degree of polymerization n = 10.8 epoxy equivalent: 1750 to 2100 manufactured by Yuka Shell Epoxy Co., Ltd.), triethylene glycol diacrylate (TEGDA). 50 parts by weight and 5 parts by weight of diphenyliodonium hexafluorophosphate, 2-
0.5 parts by weight of diethyl [p- (N-dimethylaminophenyl) ethenyl] malonate was mixed and dissolved in 100 parts by weight of 2-butanone to prepare a hologram recording material, which was used as a photosensitive solution. This sensitizing solution was applied to soda lime glass (1.1 mm thick, 5 inch square) with a doctor blade so that the film thickness would be about 20 μm, and dried to form a hologram layer.
An aqueous polyvinyl alcohol solution was applied to the application surface of this hologram recording material and dried to form a protective layer, to prepare a hologram recording medium.

This hologram recording medium was exposed using a krypton laser (409 nm) as a light source by the hologram photographing optical system shown in FIG. 2 to produce a two-beam transmissive diffraction grating. 80 after this holographic exposure
Heat treatment was performed at 30 ° C. for 30 minutes, and the hologram recording medium was entirely irradiated with a high pressure mercury lamp to fix the hologram.

The diffraction efficiency of the obtained hologram was measured by using a spectrophotometer (UV2400PC) manufactured by Shimadzu Corporation.
The measurement was performed while changing the angle (θ) of the hologram. For the measurement, the transmittance obtained by the angle at which the monochromatic light is incident on the sample and the transmittance becomes the lowest when the diffracted light from the sample is detected is 1
The value obtained by subtracting from 00 was defined as the diffraction efficiency. The visible light transmittance was measured in the same manner using the same spectrophotometer, and was 400 to 7
It was set to the minimum value of the transmittance in the range of 00 nm excluding the absorption of the reproduction light. The evaluation results are shown in Table 1.

<Example 2-6> Diethylene glycol diacrylate (DEGDA) in place of the triethylene glycol diacrylate (TEGDA) of Example 1 above,
Neopentyl glycol diacrylate (NPGD
A), ethyl carbitol acrylate (EKA),
1,6-hexanediol diacrylate (HDD
A), triethylene glycol methacrylate (TE
A hologram was prepared and fixed in the same manner as in Example 1 except that GDMA) was used, and its diffraction efficiency and visible light transmittance were measured. The evaluation results are shown in Table 1.

[0043]

[Table 1]

TEGDA; triethylene glycol diacrylate DEGDA; diethylene glycol diacrylate NPGDA; neopentyl glycol diacrylate EKA; ethyl carbitol acrylate HDDA; 1,6-hexanediol diacrylate TEGDMA; triethylene glycol methacrylate

<Examples 7-12> The bisphenol epoxy resin of the above Examples 1-6 (trade name "Epicoat 10
07 "degree of polymerization n = 10.8 epoxy equivalent: 1750
2100 manufactured by Yuka Shell Epoxy Co., Ltd.), except that a brominated epoxy resin (trade name “Araldite XAC8101” manufactured by Ciba Geigy) was used instead of the brominated epoxy resin, and a hologram was prepared and fixed in the same manner as in Example 1-6. The diffraction efficiency was measured. The evaluation results are shown in Table 2.

[0046]

[Table 2]

<Example 13-17> 2- [p- (N-dimethylaminophenyl) ethenyl] of Example 1-6 above.
A hologram was prepared and fixed in the same manner as in Example 1-6 except that thioflavin T was used instead of diethyl malonate, and the diffraction efficiency was measured. The evaluation results are shown in Table 3.

[0048]

[Table 3]

[0049]

As described above, the present invention is a thermosetting resin having at least one solvent-soluble cationically polymerizable ethylene oxide ring in a structural unit as described above,
A hologram recording material comprising a hologram layer composed of a radical-polymerizable ethylenic monomer, a photoinitiator that activates radical polymerization and cationic polymerization when exposed to actinic radiation, and a sensitizing dye.
It has a wavelength of 420 nm, and has excellent sensitivity, resolution, diffraction efficiency and transparency in the absorption wavelength of this sensitizing dye, and also has excellent heat resistance and weather resistance, is chemically stable, and is excellent in storage stability, especially in light. Since it is a compound that can spectrally sensitize the initiator, it does not contain the visible light wavelength range, so the hologram recording material is not colored, there is almost no effect of the dye remaining after hologram formation, and the appearance is colorless. It becomes transparent and has high transparency.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating the configuration of a hologram recording medium 1 made of the hologram recording material of the present invention.

FIG. 2 is a schematic explanatory diagram illustrating an optical system for hologram imaging.

[Explanation of symbols]

1 Hologram recording medium 2 base materials 3 Hologram layer 4 protective layer 5 laser 6 laser light 7 mirror 8 lenses 9 Spatial filter 10 Beam splitter

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-62169 (JP, A) JP-A-8-297455 (JP, A) JP-A-59-95531 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03H 1/00-1/32

Claims (5)

(57) [Claims] 1. A thermosetting resin (A) which has at least one solvent-soluble, cationically polymerizable ethylene oxide ring in a structural unit and has a melting point of 60 ° C. or higher, (B) a radically polymerizable ethylenic monomer, (C) A hologram recording material comprising a photoinitiator that activates radical polymerization and cationic polymerization upon exposure to actinic radiation, and (D) a sensitizing dye that sensitizes the photoinitiator. The sensitizing dye has an absorption wavelength of 350 to 420 nm, and the (C)
A hologram recording material comprising a compound capable of spectrally sensitizing a photoinitiator. 2. The thermosetting resin (A) is represented by the general formula (1)
The hologram recording material according to claim 1, wherein [Chemical 1] (In the formula, R ₁ and R ₂ each represent a hydrogen atom or a functional group selected from a methyl group, an ethyl group and a trifluoro group, and n = 1 to 20.) 3. The thermosetting resin (A) is represented by the general formula (2):
The hologram recording material according to claim 1, wherein [Chemical 2] (In the formula, n = 1 to 20.) 4. The thermosetting resin (A) has the general formula (3):
And the epoxy equivalent is 400 to 6000. 3. The hologram recording material according to claim 1, wherein [Chemical 3] 5. The hologram recording material according to claim 1, wherein the photoinitiator is any one of trihalogenomethyl-substituted s-triazine and diaryliodonium salt.