JPH01321470A - Thick film hologram - Google Patents

Abstract

PURPOSE:To put the hologram which has a large film thickness and high diffraction efficiency into practicability by using a specific transparent resin as an essential material and adding a sensitizer and a photoreaction initiator to this essential material, thereby constituting the hologram. CONSTITUTION:The essential material of the hologram constituted by using the transparent resin as the essential material and adding the sensitizer and the photoreaction initiator to this essential material is constituted of the polymer which has a carbazole ring and to which a polycarbonate resin having 25,000-100,000 weight average mol.wt. is added. The hologram is required to be formed by adding a crosslinking agent and the photoreaction initiator (sensitizer) to this resin. A basic dye such as thioflavin, org. peroxide such as benzoyl peroxide, halogen-contg. compd. such as carbon tetrabromide, etc., are used for the crosslinking agent and rubrene, merocyanine compd., etc., are used for the photoreaction initiator. The reflection type hologram which has excellent transparency, exhibits high diffraction efficiency and has the film thickness as large as about 10mum is obtd. in this way.

Description

[Detailed Description of the Invention] [Summary] Regarding thick film holograms, the purpose is to put into practical use holograms with a thick film thickness and high diffraction efficiency. In the hologram formed by adding a polymer agent, the main agent is a polymer having a carbazole ring, and a polycarbonate resin having an average weight molecular weight of 25,000 to 10,000 is added to the polymer to form an organic plastic hologram.

[Industrial application field]

The present invention relates to improvements in thick film holograms using organic plastics.

A hologram is a recording of the interference wavefront of coherent light such as a laser as a refractive index distribution on photographic film.
In addition to being used for displays, practical use as optical elements is being considered by utilizing wavelength separation, light focusing, and incident angle selection functions.

Beam scanners for bar code reading and beam scanners for laser printers have already been put into practical use using transmission holograms.

Furthermore, the use of reflective holograms with large film thicknesses in applications such as mixing windows for head-up displays is being considered.

[Conventional technology]

It is necessary for the hologram that the diffraction efficiency and transmittance do not decrease due to humidity, and that the hologram does not change color or decrease the transmittance due to light.

Conventionally, bleached silver salts, dichromate gelatin, and the like have been used as window optical materials for hologram recording.

These silver salts and dichromate gelatin have high sensitivity over the entire visible light range, but the hologram formation process is complicated, and because they use gelatin film as a binder, they are not moisture resistant. Heat-resistant.

There is a problem that environmental resistance such as light resistance is poor.

Therefore, in order to solve this problem, hologram materials mainly made of organic plastics have been proposed. (JP-A-53-15153, JP-A-56-1620, etc.) In JP-A-53-15153, polystyrene, poly-P-methylstyrene, poly-P-divinylbenzene, polyvinylaniline, polyvinylpyrrolidone, More than 100 types of organic compounds are listed, including polyvinyl carbazole, polycarbonate resin, polyurethane resin, and epoxy resin.

However, as a result of studies, the inventors have found that polymers containing carbazole rings, such as polyvinylcarbazole, have a large refractive index modulation.

■ Excellent environmental resistance.

■ Excellent transparency.

It has been found that this method is the best in terms of the following points, and that it is possible to form a hologram with high diffraction efficiency.

Hologram materials are made by adding a photoreaction initiator and aggravating dye to a base resin, and holograms are made by dissolving these materials in a solvent, coating it on a glass substrate, and printing it on a dry plate. make.

Then, after holographic exposure, using two types of solutions,
It is made by developing a dry plate.

That is, benzene is a good solvent with solubility that can swell a polymer containing a carbazole ring.

After the membrane is swollen by treatment with a first solution such as toluene, xylene, dichlorobenzene, benzyl alcohol, etc.
Pentane, which is a poor solvent for polymers containing carbazole rings,
When treated with a second solution such as hexane, heptane, octane, methyl alcohol, ethyl alcohol, acetone, methyl ethyl ketone, ethyl acetate, etc., shrinkage occurs and a refractive index change occurs according to the exposure pattern, forming a phase-type hologram. has been done.

Now, in a reflection hologram, a periodic structure of interference fringes is formed in the film thickness direction, so the thicker the film, the more interference fringes contributing to diffraction.

Therefore, in order to obtain high diffraction efficiency, it is necessary that the film thickness be large.

However, since the carbazole ring-containing polymer is brittle, it is possible to form a good film without cranks when producing a dry plate, but there is a problem that cranks are likely to occur in the film due to solvent shock during development.

These cracks do not occur when the film thickness is about 6 μm or less, but they begin to occur when the film is thicker than this, which poses a problem in that a thick hologram suitable for a reflective type cannot be formed.

[Problem to be solved by the invention]

As described above, in order to obtain high diffraction efficiency in a reflective hologram with a thick film thickness, a film thickness of 6 μm or more is required, but the problem is that cranking occurs due to development shock.

[Means to solve the problem]

The above-mentioned problem is that in a hologram constructed by using a transparent resin as a main material and adding a sensitizer and a photoreaction initiator to this main material, the main material is a polymer having a carbazole ring, and this polymer has an average weight molecular weight. This can be solved by adding a polycarbonate resin having a molecular weight of 25,000 to 100,000.

[Effect]

The inventors created a hologram by adding small amounts of various resins to a material having a carbazole ring that can obtain high diffraction efficiency as a base resin, and investigated the relationship between the added resin and the occurrence of cracks.

As a result, it was found that by adding polyester resin and polycarbonate resin, a hologram could be formed without cracking even when the film thickness was as thick as 10 μm.

However, when polyester resin is used, the solubility in the first solution used in the development process is too high, resulting in devitrification of the film, making it impossible to obtain a transparent hologram with high light transmittance. There wasn't.

The same result was obtained when a polycarbonate resin with a low molecular weight was used.

In general, the solubility of polymers in solutions decreases as their molecular weight increases, so the inventors created a hologram by adding a polycarbonate resin with a high molecular weight.As a result, they were able to create a hologram with excellent transparency and no defects such as clutter. I was able to make it.

As a result of experiments, it has been found that the average weight molecular weight of the polycarbonate resin to be added is preferably 25,000 to 100,000, and that the weight ratio of the added polycarbonate resin to the polymer having a carbazole ring is 0.1 to 10% by weight.

Note that in order to form a hologram, it is necessary to add a crosslinking agent and a photoreaction initiator (sensitizer) to the above resin, and the names of materials suitable for this are listed below.

Crosslinking agents: Basic dyes such as thioflavin and crystal violet, organic peroxides such as benzoyl peroxide, di-t-butylshiba-oxyisophthalate, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane. , halogen-containing compounds such as carbon tetrabromide, iodoform, tetraiodomethane, photoinitiators nilpurine, acridine orange, thioflavin.

Carotene orange, crystal violet, pyrylium salts, thiopyrylium salts, thiazole compounds, oxazole compounds, merocyanine compounds, etc. are used.

〔Example〕

Example 1: BoIJ-N-vinylcarbazole (weight average molecular weight 70
10,000, ■ Made by Sasame Fragrance)... 10.00 g Polycarbonate resin (polystyrene equivalent weight average molecule ffi,
77000, @Otodai Kasei)... 0.10 g Iodoform (crosslinking agent)... 1.00 g Rubrene (photoreaction initiator)... 0.20 g, Monochlorobenzene... 41. 2 go-
Dichlorobenzene ... Tetrahydrofuran ... // Dissolved in a mixed solution and filtered through a filter paper with a bore diameter of 2 μm to prepare a photosensitive solution.
A dry plate for hologram recording was prepared by spin coding on a glass substrate with a 0 fin angle so that the film thickness after drying was 10 μm.

This dry plate was irradiated with Ar laser light from both sides to perform three-beam interference exposure (spatial frequency of interference fringes: 2500 lines/dragon).

After exposure, toluene 20% by weight, xylene 80% by weight
After being immersed for 6 minutes in a mixed solution consisting of:

The sample was immersed in a mixed solution containing 80% by weight of xylene for 1 minute, then pulled out and slowly immersed in pentane, and then pulled out after 10 seconds for development.

As a result, we were able to obtain a transparent hologram with no defects such as cranks.

When this hologram was reproduced using an Ar laser, the diffraction efficiency was 62%.

In addition, as a result of measurement using a He-Ne laser, the light transmittance was 9
It was 6%.

Next, this hologram was placed in a constant temperature and humidity chamber at a temperature of 70° C. and a relative humidity of 95%, and a humidity test was conducted, but no decrease in diffraction efficiency and light transmittance was observed even after 10 days.

Example 2: In Example 1, the amount of polycarbonate resin added was O.
A photosensitive solution was prepared by changing the amount to 1.5% by weight, and a hologram was made in the same manner as in Example 1.

Table 1 shows the presence or absence of a crank and the diffraction efficiency value for this hologram. When polycarbonate was not added, cracks occurred and the diffracted light was distorted, but 0.
When 3 to 1.5% by weight was added, crack-free holograms could be obtained.

Table 1 [Effects of the Invention] According to the present invention, it exhibits excellent transparency and high diffraction efficiency,
It is possible to obtain a reflective hologram with excellent environmental resistance and a film thickness as thick as about 10 μm.

゛・-12-y

Claims (1)

[Scope of Claim] A hologram composed of a transparent resin as a main material and a sensitizer and a photoreaction initiator added to the main material, wherein the main material is a polymer having a carbazole ring, and an average amount of A thick film hologram comprising a polycarbonate resin having a weight molecular weight of 25,000 to 100,000.