JP2567273B2 - Photosensitive resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photosensitive resin composition, and more particularly to a poly (N-) having a high molecular weight and a narrow molecular weight molecule useful as a material for a volume phase hologram recording medium. Vinylcarbazole) (hereinafter abbreviated as PVCz).

(Prior Art) It has long been said that a volume phase hologram is a new optical element, and in recent years, for example, its usefulness as a coupling element of a head-up display has been noted, and its status is being established.

Conventionally, gelatin sensitized with dichromic acid has been widely known and used as a recording medium capable of recording a high-performance volume phase hologram.

Although this dichromated gelatin-based recording medium is an excellent recording medium in that a high-performance hologram can be recorded, it is inferior in heat resistance and environmental resistance, particularly in moisture resistance, and recording is easily lost due to moisture absorption. Problem. Therefore, sufficient measures are required to make the hologram moisture-proof, and for example, when applied to laser protective eyeglasses for protecting the eyes from laser, head-up display devices for automobiles, etc., the hologram is a glass plate or It is necessary to seal with various sealants, which improves workability, safety,
There was a practical difficulty in terms of weight and the like.

In order to solve the above-mentioned drawbacks of the dichromate gelatin-based recording medium, a hologram recording technique using a iodine compound as a sensitizer in a polymer having an aromatic compound as a molecular chain constituent unit such as PVCz as a new recording medium. Has been proposed (see, for example, Japanese Patent Publication No. 62-14831). Furthermore, a technique for improving these to obtain a high-performance hologram has also been proposed (see, for example, JP-A-54-101343).

(Problems to be Solved by the Invention) The above PVCz-based recording medium can provide a volume phase hologram having extremely excellent moisture resistance, light resistance and the like. However, in the dichromated gelatin-based recording medium, a volume phase hologram having a diffraction efficiency of 99.9% and a transmittance of 90% or more is prepared, whereas the PVCz-based recording medium In this case, the maximum diffraction efficiency is usually 90%, and even if it is improved, it is only 98%. Moreover, stable performance is not always obtained and there is a problem in productivity.

Also, in the case of PVCz-based recording media, fine cracks are more likely to occur on the whole of the hologram during hologram development due to the properties of PVCz, as compared with dichromated gelatin-based recording media, and the transmittance is high. Tends to decrease. In particular, when forming a black lattice image of a type with a narrow diffraction peak width, the thickness of the recording medium inevitably becomes thick as theoretically suggested, so the above-mentioned problem of cracking becomes more remarkable, and There is a problem that the transmittance decreases.

Also, when a volume phase hologram recorded on a PVCz-based recording medium is exposed to a high temperature (even at a temperature below the glass transition point) for a long time, the diffracted light peak tends to irreversibly shift to the short wavelength side. However, there is a difficulty in that the peak shift associated with the thermal history must be taken into consideration in design in order to match the wavelength of the diffracted light with the specific light.

The present inventors have previously proposed PVCz having a high molecular weight and a narrow molecular weight distribution as a means for solving the above problems.

In making a recording medium using such a high molecular weight PVCz, PVCz is dissolved in an organic solvent to form a film,
It is necessary to add a sensitizer to make it photosensitive, but even if the solution sensitized in this way is stored in a dark place, a dark reaction easily occurs and the viscosity increases and it becomes unusable. Many. In particular, such thickening is caused by the larger the molecular weight of PVCz in the solution,
The higher the sensitivity of the sensitizer, the more prominent it tends to be.

Therefore, if a photosensitive solution is prepared each time it is made into a film, the productivity will be poor, and a subtle lot difference will occur between the prepared photosensitive solutions each time, and the viscosity will increase with the passage of time. There is a problem in that the film thickness becomes non-uniform due to the change in the property and unevenness in the flow. In the hologram, the uniformity of the film is required to be 10% or less, and the nonuniformity of the film is not only the difference in the diffraction efficiency,
Since it also affects the half-value width of the diffraction peak, the quality of the hologram also deteriorates.

Therefore, it is an object of the present invention to provide a PVCz-containing photosensitive resin composition which can be handled and provided with a uniform film thickness and can be stably stored.

(Means for Solving Problems) The above object is achieved by the present invention described below.

That is, the present invention provides a photosensitive resin composition containing a poly (N-vinylcarbazole) having a weight average molecular weight of 1,000,000 or more and a molecular weight distribution of 3 or less, a sensitizer and a stabilizer in an organic solvent. The above-mentioned stabilizer is N-vinylcarbazole or a derivative thereof, which is a photosensitive resin composition.

(Operation) By using poly (N-vinylcarbazole) having a weight average molecular weight of 1,000,000 or more and a molecular weight distribution of 3 or less as a material for forming a hologram recording medium, high diffraction efficiency, high transparency, The volume phase hologram with low haze and suppressed shift of the diffraction peak wavelength is provided with high productivity, and the problems of the conventional techniques are solved.

On the other hand, PVCz conventionally used as a hologram recording medium has a polystyrene-equivalent weight average molecular weight of at least 70 to 950,000, and its molecular weight distribution is 4.5 to 5.5.
The above-mentioned various problems occur due to the weight average molecular weight and the molecular weight distribution.

When conventional PVCz as described above is used as a photosensitive solution,
It is relatively stable against thickening, and the cause of its stability is
This was due to the vinylcarbazole monomer contained in PVCz. On the other hand, since PVCz used in the present invention has been refined, it has almost no vinylcarbazole content as described above, and thus has high sensitivity but is easily thickened.

Therefore, when a vinylcarbazole monomer was added to purified PVCz to prepare a photosensitive solution, the thickening resistance and storage stability of the resulting photosensitive solution were improved.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

The PVCz in the present invention is obtained by polymerization of N-vinylcarbazole, and PVCz obtained by a usual method or PVCz commercially available has the above-mentioned weight average molecular weight and molecular weight distribution. Conventional PVCz can be purified, for example, by molecular weight fractionation with a solvent, and low molecular weight fractions can be removed to obtain PVCz having a specific weight average molecular weight and molecular weight distribution, which is the object of the present invention.

The weight average molecular weight referred to in the present invention is a polystyrene-equivalent molecular weight, and is a value obtained by gel permeation chromatography (Gel Permeation Chrromatograph) at a column temperature of 27 ° C. using tetrahydrofuran as a solvent (the column used. Is Showdex KF-807, KF80
M, exclusion limit 2 × 10 ⁸ , 3 × 10 ⁷ are connected, and 2 × 10 ^{7 to} 1.
Calibrated up to 2 x 10 ³ polystyrene).

As the molecular weight fractionation, any conventionally known fractionation method such as a method of using various solvents having different solubility in PVCz or a method of changing the concentration may be used. As an example, fractionation was performed by changing the mixing ratio of a good solvent and a poor or non-solvent to PVCz, and changing the solubility of the mixed solvent to PVCz to remove low molecular weight.

Molecular weight fractionation, as a good solvent for PVCz, for example,
Organic solvents such as dioxane are preferable, and examples of non- or poor solvents include isopropyl alcohol,
When the temperature of the mixture is raised, PVCz is sufficiently dissolved, and when this is cooled, it is mixed in such a ratio that PVCz in the high molecular weight range is precipitated to obtain a purified solvent, in which PVCz is heated and dissolved, and then cooled. At this time, PVCz of high molecular weight is precipitated and low molecular weight is in a dissolved state, so by separating the solution phase,
A weight-average molecular weight rich in PVCz of 1,000,000 or more is obtained, and by performing these operations by changing the type of solvent, the mixing ratio, etc., if necessary, the content of low-molecular weight PVCz is low and PVCz with a narrow molecular weight distribution can be obtained.

According to a detailed study of the present invention, when the purified PVCz has a weight average molecular weight of 1,000,000 or more and a molecular weight distribution of 3 or less, it is used as a volume phase hologram recording medium to obtain the above-mentioned results. It has been found that various problems are advantageously solved. In particular, those having a molecular weight distribution of 2 or less, those having a content of PVCz having a weight average molecular weight of 200,000 or less of 1% by weight or less, and PVCz having a weight average molecular weight of 1 million or more are 50% by weight or more of the total polymer. Can further advantageously achieve the object of the present invention.

Although one example of the fractionation method for obtaining the PVCz of the present invention has been described above, it is obvious that the PVCz of the present invention can be easily obtained by any purification method other than the above-mentioned fractionation method.

The PVCz-containing photosensitive resin composition having the above specific weight average molecular weight and molecular weight distribution contains the PVCz, the sensitizer and the stabilizer as PV.
It is obtained by dissolving it in a good solvent for Cz, and the solution viscosity obtained at 20 ° C. is in the range of 50 to 5,000 cps, preferably 300 to 2,000 cps. These viscosities vary depending on the type of organic solvent used, but for example, the amount of PVCz added to the organic solvent is preferably about 2 to 14 g per 100 cc of the organic solvent. Also, from the viewpoint of coatability, 2,000 cps
Since the viscosity up to that is preferable, if the viscosity is higher than this, it is preferable to dilute with a suitable solvent to reduce the viscosity to a suitable value before use.

Considering the solubility for PVCz and the stability for the sensitizer used, preferred organic solvents are benzene, xylene, chlorobenzene, chloroform, dichloroethane,
Examples include dichloroethylene, trichloroethylene, or a mixture thereof.

The dissolution of PVCz may be carried out by a normal dissolution operation such as putting PVCz in an organic solvent, heating it as necessary, filtering to remove insoluble matter, and removing air bubbles, and is not particularly limited.

As a sensitizer added to the above solution, PVCz is 400 nm
Since it has no light absorption band on the longer wavelength side, it must be previously activated by a halogen compound, preferably an iodine compound and / or a bromine compound, for radiation when used as a hologram recording medium. .

Such a halogen compound coexists in PVCz to form a recording layer having sufficient sensitivity in the visible wavelength region, and preferable examples thereof include carbon tetraiodide, iodoform, and tetraiodoethylene. , Iodine compounds such as triiodoethane, tetraiodoethane, pentaiodoethane, hexaiodoethane, carbon tetrabromide and ethylene tetrabromide, and bromine compounds. These halogen compounds are
100 to 1 part by weight is added to 100 parts by weight of PVCz.

If the addition amount of the halogen compound is too small as described above, the sensitivity of the obtained recording medium is low, and it takes a long time for exposure, which is not preferable.
Undecomposed halogen compounds remain in the recording medium, and it is necessary to remove all of them later, which is not preferable because it causes voids in the recording medium.

The stabilizer added to the solution has an action of suppressing the reaction of PVCz in the solution and preventing thickening of the solution. In the present invention, for example, N-vinylcarbazole and its alkyl-substituted Body, a halogen-substituted compound, specifically, 3-chlorovinylcarbazole, 3-bromovinylcarbazole, 3-iodovinylcarbazole, 3-
Methyl vinyl carbazole, 3-ethyl vinyl carbazole and the like are used.

Although these stabilizers cannot be generally specified depending on the kind of the stabilizer to be used, they are generally 10 to 0.01 mol, preferably 2 to 0.1 mol, relative to 1 mol of the sensitizer. If it is used in excess of the range, the sensitivity of the recording layer formed from the photosensitive solution will be lowered, while if it is too small, suppression of thickening will be insufficient, leading to deterioration in workability during film formation and hologram quality, which is not preferable.

Further, the N-vinylcarbazoles in the present invention hardly flow into the solvent at the time of development within the above-mentioned addition amount range, and
It was confirmed that the above monomers did not remain in the hologram film, and there was no difference in hologram performance from the case of no addition.

A case where the photosensitive resin composition of the present invention is used for hologram recording is described as an example.

A recording medium comprising the photosensitive resin composition of the present invention is prepared by appropriately adjusting the viscosity of the above-mentioned photosensitive resin composition and forming a coating film on a suitable substrate such as a glass plate or a plastic film. Obtained by

The recording medium formed as described above is exposed by an optical system as shown in FIG. 1 by using a coherent laser having two light beams of coherent visible light up to 560 nm, that is, object light and reference light.

Subsequent to the exposure step, the recording layer is immersed in a solvent that hardly elutes the PVCz forming the recording layer and the cross-linked product of PVCz generated by the photoreaction.

The developing process to be performed next consists of two steps, a swelling process and a shrinking process.

That is, a recording layer on which a hologram latent image is formed and a halogen compound is removed by the exposure step is treated with a swelling liquid which is a first solvent to cause swelling according to the formed hologram pattern. In the subsequent treatment with the second solvent, the recording layer in the swollen state is shrunk to amplify and immobilize the hologram according to the swollen state.

The swelling solution, which is the first solvent in the hologram development step, is a solvent that hardly elutes in a short time with respect to the crosslinked and uncrosslinked products of PVCz generated as a result of the photoreaction between PVCz and the halogen compound. is there. As such a solvent, one having an appropriate swelling power is selected or combined from the good solvents mentioned as the purification solvent in the present invention.

Further, the contraction liquid as the second solvent does not have a swelling or dissolving action on the recording layer, and any solution compatible with the swelling liquid can be used. An appropriate solvent is selected or used in combination from the solvents.

Also, the processing conditions such as temperature and time of each process vary depending on the type of recording layer and the type of solvent used and cannot be specified unconditionally.
A sufficient effect can be obtained by treating at a temperature of about 70 to 70 ° C. for a few seconds to a few minutes.

The hologram film obtained as described above can, of course, be used as it is adhered to the substrate, and since PVCz used in the present invention has a high molecular weight, it has sufficient strength even when peeled from the substrate. Since it has the hologram film, it can be sufficiently used in various applications even as a hologram film separated from the substrate.

(Effect) By using the photosensitive resin composition of the present invention having the specific weight average molecular weight and molecular weight distribution as described above and having the viscosity in the specific range, a hologram recording layer having a uniform thickness of 3 to 20 μm can be obtained. It is formed. Further, by containing the stabilizer, it is possible to prevent thickening and form a hologram recording layer having a uniform thickness even after storage for a long time.

(Examples) Next, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1 30 g of PVCz (Rubican M-170, manufactured by BASF) is mixed with dioxane / isopropyl alcohol mixed solution (weight ratio 100/40) 600 m
In addition to the l part, heat to 80 ° C to dissolve and homogenize, then 2
Cooled to 5 ° C.

Precipitated PVCz was separated by decantation and separated
PVCz was added to 200 ml of dioxane / isopropyl alcohol mixed solution (weight ratio 100/40) and stirred to wash the polymer to obtain purified PVCz.

Dissolve part of the above sample in tetrahydrofuran,
Using a gel permeation chromatograph at a column temperature of 27 ° C, the column was connected to Shodex (Showa Denko KF-807, KF80M), and the weight average molecular weight and molecular weight distribution were determined based on polystyrene, It was as follows.

Weight average molecular weight 1.52 million Molecular weight distribution 1.48 PVCz content with a molecular weight of 200,000 or less 0.8 wt% PVCz content with a molecular weight of 1 million or more 62 wt% This sample 5.2 g, carbon tetraiodide 0.402 g and N-vinylcarbazole 0.15 g Was added to 120 cc of chlorobenzene, and dissolved by stirring in a dark place to completely dissolve and obtain a photosensitive resin composition of the present invention.

When this solution was measured at 25 ° C. with an E-type viscometer (VISCONIC ED, manufactured by Tokyo Keiki Co., Ltd.) using a 3 ° cone, the results shown in FIG. 2 were obtained.

Example 2 A photosensitive resin composition of the present invention was obtained in the same manner as in Example 1, except that the same amount of N-vinylethylcarbazole was used as the stabilizer.

When this solution was measured at 25 ° C. with an E-type viscometer (VISCONICED, manufactured by Tokyo Keiki Co., Ltd.) using a 3 ° cone, the results shown in FIG. 2 were obtained.

Use Example 1 The photosensitive resin composition of the above Example 1 was mixed, stirred and demixed, and after 3.5 hours, a glass plate washed was coated with a spinner (manufactured by Kyowa Semiconductor Co., Ltd.) and dried.
A recording layer of 9.8 μm was formed. The uniformity of the thickness of this recording layer was measured by a spectrophotometer using a monitor wavelength of 350 nm and a mask having a hole of 5 mmφ.
It was within 5 μm.

This recording layer was exposed with the optical system shown in FIG. 1 using an Ar laser (488 nm) to record a hologram.

After the exposure, it was dipped in toluene at 35 ° C. for 2 minutes and dipped in xylene at 35 ° C. for 2 minutes, further dipped in heptane at 20 ° C. for 2 minutes and dried to obtain a volume phase hologram.

The reflection diffraction efficiency of the hologram was measured and found to be 51
The maximum reflection diffraction efficiency is 92% with 8 nm light, the transmittance with 600 nm light is 85%, and the haze (total haze value) is
Haze meter based on JIS K7105 (manufactured by Nippon Denshoku Co., Ltd.)
It was 1.2% when measured by.

Comparative Example 1 A photosensitive resin composition of Comparative Example was prepared in the same manner as in Example 1 except that N-vinylcarbazole was not used, and the change in viscosity with time of the solution was measured equally. Got the result. A solution thickened to 5,000 cps or more was difficult to use because it was difficult to homogenize it even when diluted with a solvent.

[Brief description of drawings]

FIG. 1 shows the hologram recording optical system used in the examples.
FIG. 2 shows the change with time of the viscosity of the PVCz solution.

Front Page Continuation (72) Inventor Tetsuro Kuwayama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroyoshi Kishi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-49-6914 (JP, A) JP-A-54-101343 (JP, A) JP-A-2-3082 (JP, A) JP-A-53-15153 (JP, A) Kai 60-258579 (JP, A) JP 60-222882 (JP, A) JP 62-275283 (JP, A) JP 45-24606 (JP, B1)

Claims (3)

(57) [Claims] 1. A photosensitive resin composition comprising a poly (N-vinylcarbazole) having a weight average molecular weight of 1,000,000 or more and a molecular weight distribution of 3 or less, a sensitizer and a stabilizer in an organic solvent. A photosensitive resin composition, wherein the stabilizer is N-vinylcarbazole or a derivative thereof. 2. The photosensitive resin composition according to claim 1, wherein the sensitizer is a halogenated carbon. 3. The photosensitive resin composition according to claim 1, wherein the amount of the stabilizer is 10 to 0.01 mol per mol of the sensitizer.