JPH11133841A - Hydrophilic hologram recording composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel hydrophilic hologram recording material having an excellent adhesion property to a hydrophilic surface, holding stability of a hologram and excellent handling quality. SOLUTION: This recording medium compsn. contains (A) polyethylene glycol of a mol.wt. of 5,000 to 30,000, (B) at least one of an oligomer and monomer having a refractive index of >=1.50 and having a (meth)acryloyl group as a photopolymerizable group and (C) a photoinitiator, in which the weight ratio of the component (A) and the component (B) is 1:9 to 3:7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel hologram recording material composition, and more particularly to a hologram recording material composition capable of real-time recording.

[0002]

2. Description of the Related Art A hologram is obtained by recording an interference pattern of coherent light of a laser on a photosensitive material or the like. These are used as three-dimensional image creation and optical elements. The characteristics required for hologram recording materials are He
-Ne (wavelength 633 nm), Ar (wavelength 515,488 nm), He-Cd (wavelength
442 nm), the hologram has high diffraction efficiency, high resolution, and easy development processing.

[0003] As typical conventional light-sensitive materials, there have been known those obtained by subjecting dichromated gelatin and silver salt dry plates used for ordinary photographic materials to bleaching treatment (for example, Masato Nakajima and Kazuo Hanano). Display Hologram Handbook, p.66-67, Akatsuki Shokan (1985), edited by Teruyuki Kose, Hiroyoshi Saito, Shunichi Tanaka, Junpei Tsujiuchi, Takeshi Haoka, "Optical Engineering Handbook" p.351-353, Asakura Shoten (1986) . However, although dichromated gelatin has high diffraction efficiency, and silver salt dried plate that has been subjected to bleaching treatment has high sensitivity, all of these are complicated in the process of hologram production, and particularly require wet development processing. There was a disadvantage that it was done.

[0004] As a method for overcoming this drawback, a photopolymerizable recording material containing cyclohexyl methacrylate and N-vinylcarbazole as photopolymerizable monomers and a photoinitiator as main components or 1 as an inert component not involved in polymerization is used. A method using a phenylnaphthalene, a photopolymerizable recording material containing butyl methacrylate and ethylene glycol dimethacrylate as photopolymerizable monomers and a photoinitiator as main components is known (WJ Tomlinson et al., Appl. Op.
t., vol 15, 534 (1976)) and are nowadays commonly known as liquid and solid photopolymers. However, such a photopolymer has a drawback that it is not hydrophilic, and thus has poor adhesion to a hydrophilic surface such as a glass plate. The use of an organic solvent has the disadvantage of poor handling.

On the other hand, as a hydrophilic hologram recording material, for example, a recording material in which a photopolymerizable monomer such as lithium acrylate and a photoinitiator are mixed with poly-N-vinylpyrrolidone is known. However, this photopolymer has the disadvantage that it requires a moisture activation step.

Therefore, there has not been known a hydrophilic hologram recording material which does not require the above-mentioned activation step and has good adhesion to a hydrophilic surface such as a glass plate.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel hydrophilic hologram recording material having excellent adhesion to a hydrophilic surface, excellent storage stability of a hologram, and excellent handleability. It is in.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned state of the art, the present inventors have considered that polyethylene glycol has a low refractive index and is advantageous from the viewpoint of selecting a photopolymerizable oligomer / monomer to be combined. Focusing on polyethylene glycol as an inert component, furthermore, it should be a transparent film after polymerization, and processing such as development and fixing should be simple,
In order to satisfy various conditions such as being able to perform hologram recording with excellent practical performance such as laser sensitivity, diffraction efficiency, and resolution, the above-mentioned inactive components, oligomer / monomer and photoinitiator composition were studied diligently. . As a result, the above object can be achieved by a polyethylene glycol having a specific molecular weight, an oligomer / monomer having a specific refractive index having a specific photopolymerizable group, and a photopolymerizable material having a photoinitiator as a constituent. And completed the present invention.

That is, the present invention relates to (A) a polymer having a molecular weight of 5,000
0 to 30,000 polyethylene glycol; (B) at least one of oligomers and monomers having a refractive index of 1.50 or more and having a (meth) acryloyl group as a photopolymerizable group; and (C) a photoinitiator. The present invention relates to a hydrophilic hologram recording material composition, wherein the composition has a weight ratio of the component (A) to the component (B) of 1: 9 to 3: 7.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each component of the hydrophilic hologram recording material composition of the present invention will be described in detail.

[0011] In the present invention the material composition, for use as an inert ingredient serving base resin (A) polyethylene glycol has a molecular weight consisting of -CH ₂ -CH ₂ -O- repeat units of linear backbone is 5,000 It is a solid substance of about 30,000. A particularly preferred molecular weight is around about 20,000. If the molecular weight is less than 5,000, the storage stability of the hologram decreases, while if it exceeds 30,000, (B)
It is not preferable because the compatibility with the oligomer / monomer tends to decrease. Further, since this polyethylene glycol usually has a low refractive index of about 1.45 to 1.48, it has an advantage that the diffraction efficiency of the hologram is high.

In the composition of the present invention, the oligomer and monomer (B) used as an auxiliary agent have a role of radically photopolymerizing and entanglement of a polyethylene glycol chain to form a polymer. Use at least one. The component (B) is at least one of an oligomer and a monomer having a refractive index before polymerization of 1.50 or more and having a (meth) acryloyl group as a photopolymerizable group. Here, the (meth) acryloyl group of the photopolymerizable group means an acryloyl group, a methacryloyl group or both, and usually has at least one at the molecular terminal. It is necessary that this has a refractive index of 1.50 or more. When used as a mixture of two or more, it is necessary that the mixture has this refractive index. If the refractive index is less than this value, it is difficult to obtain a hologram with high diffraction efficiency, which is not preferable. A preferred refractive index is about 1.51 to 1.59. Refractive index is 1.60
The above are not preferred because the compatibility with the component (A) often becomes insufficient.

Specific examples of such oligomers include:
For example, polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate and the like can be mentioned.

Among these oligomers, polyester (meth) acrylates include, for example, at least one (meth) acrylate at the end of an esterified product of a polybasic acid such as terephthalic acid or isophthalic acid and a polyol such as ethylene glycol or propylene glycol. It has an acryloyl group. Also, epoxy (meth) acrylate, for example,
It is obtained by reacting (meth) acrylic acid with a bisphenol A type epoxy resin, a phenol novolak type epoxy resin or the like. In addition, urethane (meth) acrylate,
For example, a polyisocyanate obtained by a reaction between a diisocyanate and a polyol is reacted with a hydroxyl group-containing (meth) acrylate.

These polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth)
Preferred oligomers such as acrylates have about 1 to 6 phenyl groups in the molecule and have a molecular weight of 40.
It is about 0 to 5,000. When the molecule has a phenyl group, there is obtained an advantage that, with the progress of photopolymerization, phase separation easily occurs with (A) polyethylene glycol, and the diffraction efficiency is further improved.

Specific examples of the above-mentioned monomer include, for example, pentaerythritol tri (meth) acrylate,
3-phenoxy-2-hydroxypropyl (meth) acrylate, polyethylene glycol di (meth) acrylate, hexanediol mono (meth) acrylate,
(Meth) acryloylmorpholine and the like can be mentioned. These monomers having a refractive index of 1.50 or more can be used alone as the component (B), but are preferably used in combination with the oligomer as a diluent for the oligomer.

The weight ratio of the component (A) to the component (B) is 1: 9 to 3: 7 in the composition of the present invention.
It is necessary to be. Outside this range, the diffraction efficiency of the obtained hologram becomes low, and the base material becomes difficult to dissolve, making it difficult to withstand practical use.

As the photoinitiator (C) in the composition of the present invention, He-Ne (wavelength 633 nm), Ar (wavelength 515,488 nm), He-Ne
What absorbs laser light, such as Cd (wavelength 442 nm), and generates a radical is used. Preferred examples of such a photoinitiator include a carbonyl compound alone and a combination of a carbonyl compound and a dye. Further, a combination of an amine compound and a dye, a combination of a borate compound and a dye, and the like are also effective as a photoinitiator.

Examples of the carbonyl compound include benzyl, benzoin ethyl ether, benzophenone, and diethoxyacetophenone. Examples of the dye include Michler's ketone, acridine yellow, merocyanine, methylene blue, camphorquinone, eosin, and decarboxylated rose bengal. it can. Examples of the amine compound include triethanolamine, triisopropanolamine, and 2-dimethylaminobenzoic acid.
Examples of the borate compound include triphenyl-n-butyl borate and the like.

Specific examples of the carbonyl compound-dye combination include benzyl-Michler's ketone and benzyl-acridine yellow. Further, as the dye to be combined with the amine compound, eosin, methylene blue or the like is preferable, and as the dye to be combined with the borate compound, decarboxylated rose bengal or the like is preferable.

The amount of the photoinitiator (C) in the composition of the present invention, when a carbonyl compound is used, is usually about 0.3 to 5% by weight based on the oligomer monomer of the component (B). . When a dye is combined with a carbonyl compound, an amine compound or a borate compound, the former compound and the dye are each added to the component (B) in an amount of 0.1%.
About 3 to 5% by weight is used.

The composition of the present invention comprises the above-mentioned component (A),
The components (B) and (C) are essential components, but additives such as a thermal polymerization inhibitor, water, and a hydrophilic organic solvent can be added as necessary.

In the composition of the present invention, the essential components of the components (A), (B) and (C) and, if necessary, other optional components are stirred in a glass container or the like. Can be suitably prepared. At this time, in order to promote the dissolution, for example, the mixture may be heated to about 40 to 60 ° C., or a small amount of water or ethyl alcohol may be added.

When a hologram is formed using the recording material composition of the present invention, for example, it can be performed as follows. As an example, the recording material composition is applied on a surface material such as glass or plastic, and a surface material for a cover is applied thereon to form a three-layer structure. Place it on the striped pattern created by the interference of object light. In this state, an interference fringe that normally becomes a hologram after several seconds to several minutes can be recorded.

Here, the light amount is preferably about 100 to 1,000 mJ / cm ^{2 as} a product of the light intensity and the irradiation time. If it is less than this range, recording is difficult, and if it is more than this range, the diffraction efficiency of the hologram tends to decrease, which is not preferable. Further, post-processing such as development and fixing after recording the interference fringes is not particularly required, but the entire surface may be irradiated with light or subjected to heat treatment just in case.

Further, a hologram can be suitably copied using the material composition of the present invention. That is, as an example, the material of the present invention is placed on a hologram plate serving as an original through a thin polyethylene terephthalate film having a thickness of about 10 μm, and a 100 W high-pressure mercury lamp is irradiated from above on the hologram plate at a distance of about 10 μm. As a result, interference occurs between the reference light that enters the material layer without diffracting and the diffracted light of the original image (that is, the object light), and the copied hologram is obtained, which is fairly faithful to the original image. The diffraction efficiency is defined by the ratio of the intensity of the first-order diffracted light to the intensity of the illumination light for reproduction incident on the hologram, and the diffraction efficiency of the copied hologram is affected by that of the original.

In the recording material composition of the present invention, the component (A) of the main component and the component (B) of the sub-agent are completely dissolved before exposure, but the photo-polymerization of the sub-agent occurs upon irradiation with laser light. It becomes a polymer, and finally becomes a hologram recording film.

That is, when an interference pattern is exposed on the recording material composition of the present invention, first, oligomers and
The monomer polymerizes, causing volume shrinkage of that portion. The unpolymerized material flows into the dent from the portion where the amount of light is small, and due to the phase separation of the components (A) and (B), the polyethylene glycol is diffused to the portion where the amount of light is small, and the oligomer / monomer is changed to the portion where the amount of light is large. Diffusion moves, and polymerization proceeds further. On the other hand, the polymerization progresses in the portion where the light amount is small, although a little delay occurs compared to the portion where the light amount is large.
As a result, a polymer having a high refractive index accumulates in a portion having a large amount of light, and a polymer containing a large amount of polyethylene glycol having a low refractive index accumulates in a portion having a small amount of light. Therefore,
An interference pattern based on the composition distribution according to the amount of light, that is, the difference in the refractive index between the portion having a large amount of polyethylene glycol and the portion having a large amount of the oligomer / monomer polymer can be stably recorded in real time. The recording material composition of the present invention is hydrophilic and does not use a harmful organic solvent, so that it is easy to handle. Since both the component (A) and the component (B) have a sufficiently high molecular weight, they have excellent storage stability. Also, there is no disadvantage that both components are re-diffused after recording and the recording becomes unclear.

[0029]

The present invention will now be described more specifically with reference to examples and comparative examples.

Example 1 20 g of polyethylene glycol having a molecular weight of 20,000 (refractive index: 1.47; hereinafter, referred to as "PEG 20000")
And epoxy acrylate (Osaka Organic Chemical Industry Co., Ltd.)
"Viscort 540", molecular weight 480, viscosity 20,
2,000 cps / 25 ° C.), a mixture of 20 g of 3-phenoxy-2-hydroxypropyl acrylate and 20 g of pentaerythritol triacrylate (refractive index 1.5
2) and benzoin ethyl ether (2% by weight based on the above mixture) were added, and a resin layer having a thickness of about 10 μm was placed between a 50 × 60 × 1.5 mm glass plate and a 10 μm thick polyethylene terephthalate film. To form a three-layer structure. Another hologram plate on which 70 lines / mm lines were recorded (diffraction efficiency about 60%, resolution about 2000
Book / mm) and a 100 W high-pressure mercury lamp (365 nm, 410 n) at a distance of about 10 cm from above
m having a peak wavelength around 430 nm). In 2-3 minutes, a bright hologram with no coloring and excellent transparency and a diffraction efficiency of about 30% could be reproduced. The fact that a good hologram can be obtained by the copying method in this way means that
This proves that holograms can be produced by laser interference. The obtained hologram maintained a stable image for a long period of 3 months or more even when the cover film was peeled off.

Comparative Examples 1 and 2 Instead of PEG 20000, the molecular weight was 400 or 2,0.
00 and two types of polyethylene glycol (refractive index 1.4)
6 or 1.47, hereinafter “PEG400” or “PEG2”
000 "), the same procedure as in Example 1 was carried out on a recording material composition comprising the same components as in Example 1 except that 20 g of the recording material composition was used. However, when the cover film was peeled off and left to stand, it took several minutes when PEG 400 was used.
One day after using 00, the hologram disappeared.

With respect to the holograms obtained in Example 1 and Comparative Examples 1 and 2, the hologram forming properties and hologram stability when the kind of polyethylene glycol was changed are shown in Table 1. The hologram-forming property was good when the diffraction efficiency was 20% or more. The hologram stability was evaluated based on the time (hr) until no interference color was generated when the hologram was held over an electric lamp.

[0033]

[Table 1]

Example 2 A resin having the same composition as in Example 1 (PEG 20000
0 g and the oligomer-monomer mixture of Example 1
g), 2% by weight of benzoin ethyl ether, based on the mixture, and 2% by weight of benzyl and Michler's ketone, respectively, based on the mixture are added.
A two-layer glass plate having a three-layer structure was sandwiched between two glass plates having a thickness of 10 μm to prepare a photosensitive plate for hologram recording. Next, an interference pattern was formed using a He-Cd laser beam, and the photosensitive plate was exposed (150 mJ / cm ² ). With this operation alone, the interference pattern could be recorded in a few minutes. No development or fixing operation is required. Since the recording layer is sandwiched between two glass plates, the thickness of the resin film is uniform even after exposure,
Since there is no unevenness between the portion where the light hits the film surface strongly and the portion where the light hits the film surface weakly, it is understood that the recording is performed by the refractive index modulation. Transparent and bright hologram with little absorption in the visible part (diffraction efficiency 60%, resolution 2000)
Book / mm or more). A stable image was maintained even when the glass plate was peeled off.

Example 3 Epoxy acrylate ("Biscoat 540", manufactured by Osaka Organic Chemical Industry Co., Ltd.) was added to 30 g of PEG 20000,
A mixture (40 g of molecular weight 480, viscosity 20,000 cps / 25 ° C.) and 30 g of 3-phenoxy-2-hydroxypropyl acrylate (refractive index 1.53), and 2% by weight of benzyl and Michler's ketone were added to the mixture. Thus, a recording material composition was prepared. This was carried out in the same manner as in Example 1 to a thickness of about 8 μm between a glass plate of 50 × 60 × 1.5 mm and a polyethylene terephthalate film having a thickness of 10 μm.
m, to produce a photosensitive plate. Next, He-C
An interference pattern (200 mJ / cm ² ) was created using d-laser light and applied to a photosensitive plate. With this operation alone, the interference pattern could be recorded with good reproducibility in a few seconds to several minutes by photopolymerization. No development or fixing operation was required, and a stable hologram (diffraction efficiency 60% or more, resolution 3000 or more / mm) was obtained.

Example 4 To 25 g of PEG 20000 was added urethane acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., "Biscoat 823").
Molecular weight 1,350) 30 g, acryloyl morpholine 2
5 g and pentaerythritol triacrylate 20 g
(With a refractive index of 1.51) and 2% by weight of benzoin ethyl ether based on the mixture to prepare a recording material composition. This was sandwiched between a glass plate of 50 × 60 × 1.5 mm and a polyethylene terephthalate film having a thickness of 10 μm so that the resin layer had a thickness of about 10 μm to form a three-layer structure. A refractive index change type hologram plate on which 100 lines / mm were recorded was closely adhered thereon, and the same high-pressure mercury lamp of 100 W as in Example 1 was used thereon.
Irradiation was performed from a distance of 0 μm. In about 2 minutes, a bright hologram with no coloring and excellent transparency and a diffraction efficiency of about 30% could be reproduced. As a result, a stable image was maintained for a long period of 3 months or more even when the cover film was peeled off.

[0037]

According to the hologram recording material composition of the present invention, by simply exposing the interference fringes based on the laser beam, the hologram recording material composition diffuses into the portion containing a large amount of polyethylene glycol and the portion containing a large amount of the oligomer / monomer polymer. A hologram having a refractive index modulation that has been separated can be recorded, and the hologram can be easily copied. Further, since it is hydrophilic, it has excellent adhesion to a hydrophilic surface, and does not use a harmful organic solvent, can omit post-processing such as development, is easy to perform various operations, and is excellent in handleability. In addition, since polyethylene glycol has a low refractive index, there are abundant oligomers and monomers to be selected, and it is widely applied and industrially advantageous. Further, since polyethylene glycol having a specific range of molecular weight is used, the stability of the image itself is excellent.

Claims (1)

[Claims] (A) a molecular weight of 5,000 to 30,000
And (B) at least one of oligomers and monomers having a (meth) acryloyl group as a photopolymerizable group having a refractive index of 1.50 or more, and (C) a photoinitiator, and ( A) Component: (B)
A hydrophilic hologram recording material composition, wherein the weight ratio of the components is 1: 9 to 3: 7.