JP2567272B2 - Photosensitive resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photosensitive resin composition, and more specifically to a poly (N-) having a high molecular weight and a narrow molecular weight distribution 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 drawbacks of the dichromated gelatin-based recording medium as described above, 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.

In the case of a PVCz-based recording medium, compared to a dichromated gelatin-based recording medium, due to the properties of this PVCz, fine cracks are more likely to occur throughout the hologram during hologram development, and the transmittance is 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.

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 contains 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, and has a viscosity at 20 ° C. Is in the range of 50 to 5,000 cps.

(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.

Further, in the solution of PVCz, the storage stability can be improved by simultaneously adding a sensitizer and a stabilizer to prepare a photosensitive solution.

(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.

In molecular weight fractionation, as a good solvent for PVCz,
For example, pyridine, quinoline and derivatives thereof, cyclic ethers such as dioxane and tetrahydrofuran, benzene, toluene, xylene (ortho, meta, para and mixtures thereof), ethylbenzene, n-propylbenzene, cumene, phenol, cresol , Chlorobenzene, dichlorobenzene, nitrobenzene, benzyl alcohol, benzyl chloride, benzyl bromide,
Benzene and naphthalene derivatives such as α-methylnaphthalene and α-chloronaphthalene, halogen-substituted saturated or unsaturated hydrocarbons such as pyran, dichloromethane, chloroform, trichloroethylene, trichloroethane, dichloroethane and bromoform, acetone, methyl ethyl ketone, methyl Ketones such as isobutyl ketone and cyclohexanone; esters such as ethyl acetate and ethyl formate;
Other amines, amides and the like can be mentioned, and an appropriate one is selected or used in combination from these.

The non- or poor solvent used for molecular weight fractionation includes, for example, n-pentane, n-hexane, n-heptane, n-heptane,
Alkanes such as octane, isooctane and cyclohexane, cycloalkanes, alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, n-amyl alcohol and isoamyl alcohol; Ethers such as diethyl ether, methyl ethyl ether, diisopropyl ether and the like can be mentioned, and appropriate ones are selected or used in combination.

A good solvent and a poor solvent as described above, when the mixture is heated, PVCz is sufficiently dissolved, and when cooled, it is mixed with a ratio at which PVCz of a high molecular weight range is precipitated to obtain a purified solvent,
The PVCz is dissolved therein by heating and then cooled. At this time, PVCz of high molecular weight is precipitated and low molecular weight is in a dissolved state, so that by separating the solution phase, the weight average molecular weight is 10
The ones with abundance of 10,000 or more PVCz are obtained, and these operations are performed by changing the type of the solvent, the mixing ratio, and the like as necessary, so that the content of the low-molecular-weight PVCz is small and the molecular weight distribution is narrow. PVCz is obtained.

According to a detailed study by the present inventor, when the weight average molecular weight of the purified PVCz is 1,000,000 or more and the molecular weight distribution thereof is 3 or less, it is used as a volume phase hologram recording medium, and It has been found that various problems such as these 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 ml 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.

Further, if a high boiling point organic solvent is used, the evaporation of the solvent during film formation is slow, high temperature is required for evaporation, and bubbles are generated in the film, which is not preferable. Therefore, it is preferable to select the organic solvent having a boiling point of about 50 to 150 ° C., for example.

Considering solubility and boiling point for PVCz, preferred organic solvents include benzene, xylene, chlorobenzene, chloroform, dichloroethane, among the above good solvents.
Examples thereof include dichloroethylene, trichloroethylene, pyridine, dioxane, tetrahydrofuran, 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
It is added to PVCz in a weight ratio of 1 to 0.5, for example.

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.

Further, the stabilizer added to the solution has an action of suppressing the reaction of PVCz in the solution and preventing the thickening of the solution, for example, benzophenone-based, triazole-based, quinone-based, hydroquinone-based, diphenylpicryl. Any known stabilizer such as luhydrazyl can be used, and more specifically, thiobenzophenone, floranyl, chloranil, bromanil, dichlorodicyanoquinone, diphenylpicrylhydrazyl and the like can be mentioned. Although these stabilizers cannot be generally specified depending on the kind of the stabilizer used, they are generally in the range of about 0.1 to 5 parts by weight per 100 parts by weight of PVCz.

Furthermore, in the present invention, it is better not to use a plasticizer in the preparation of the recording medium.For example, when the plasticizer is mixed, the plasticizer remaining without being eluted in the swelling / shrinking step during development swells like PVCz. This is because it must be subjected to a contraction action, and after the contraction, a refractive index distribution other than the modulation of the refractive index satisfying the plug condition may occur in the recording medium. Of course, it cannot be said that it cannot always be used within the range where the above-mentioned inconvenience does not occur.

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, not only the PVCz constituting the recording layer but also the unreacted halogen in the recording layer was immersed in a solvent that hardly elutes the cross-linked product of PVCz generated by the photoreaction. Only the compound is eluted almost completely to remove the color. This step can also serve as the swelling step described below.

The subsequent developing step consists of two steps, a swelling step and a shrinking step, and can be performed, for example, in the same manner as the method described in JP-B-62-014831.

It is natural that the hologram film obtained above can be used while being 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, The peeled hologram film can be sufficiently used for various purposes.

(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 including the stabilizer, it is possible to prevent thickening and form a hologram recording layer having a uniform film thickness even after long-term storage.

Further, the volume phase hologram obtained by using the hologram recording layer described above is improved to 99.9% compared to the maximum diffraction efficiency of 98% of the conventional volume phase hologram using PVCz. The transmittance of 80% at 600 nm was improved to 92%, and the haze of 12% at a thickness of 10 μm was improved to 2% or less. Further, the film was blue-shifted by 20 nm after being left at 140 ° C for 2 hours. Was within 1 nm.

(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 l, heat to 80 ° C to dissolve and homogenize
Cooled to ° C.

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

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

Weight average molecular weight 1.43 million Molecular weight distribution 1.73 Content of PVCz with a molecular weight of 200,000 or less 0.3% by weight Content of PVCz with a molecular weight of 1 million or more 52% by weight 5.2 g of this sample, 0.402 g of carbon tetraiodide and 4,4'-tetra Methyldiaminothiobenzophenone (0.21 g) was added to chlorobenzene (120 ml), and dissolved by stirring in a dark place to completely dissolve it to 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 dioxane / isopropyl alcohol mixed solution (weight ratio 100/30) was used as a purification solvent in Example 1,
Others were the same as in Example 1 and the following results were obtained.

Weight average molecular weight 1.59 million Molecular weight distribution 1.89 Content of PVCz with molecular weight of 200,000 or less 62% by weight Content of PVCz with molecular weight of 1 million or more 0.1% by weight This sample 5.2g, carbon tetraiodide 0.402g and diphenylpicrylhydrazyl 0.3 g was added to 120 ml of chlorobenzene, and dissolved by stirring to completely dissolve it to 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 3 The following results were obtained in the same manner as in Example 1 except that a pyridine / methyl alcohol mixed liquid (weight ratio 100/70) was used as the purification solvent in Example 1.

Weight average molecular weight 1.41 Molecular weight distribution 2.40 PVCz content with molecular weight of 200,000 or less 0.9 wt% PVCz content with molecular weight of 1 million or more 58 wt% This sample 5.2 g, carbon tetraiodide 0.402 g and chloranil
0.19 g was added to 120 ml of chlorobenzene and dissolved by stirring to completely dissolve it to 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.

Use Example 1 The photosensitive resin composition of the above Example 1 was applied onto a washed glass plate using a spinner (Mikasa 1M) and dried.
A recording layer of 7.2 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.

When the reflection diffraction efficiency of the above hologram was measured with a reflection spectrophotometer (Hitachi u-3400), the maximum reflection diffraction efficiency was 99% at 518 nm light, and the transmittance at 600 nm light was 87%.
Furthermore, the haze (total haze value) was measured with a haze meter (manufactured by Nippon Denshoku Co., Ltd.) based on JIS K7105.
It was 1.7%.

Next, after the hologram was held at 140 ° C. for about 5 hours in a nitrogen atmosphere, the characteristics of the hologram were measured by the above optical system. As a result, no peak shift of the maximum diffraction efficiency was observed, and no change in the maximum diffraction efficiency and the haze value was observed. There wasn't.

Use Example 2 A recording layer was formed in the same manner as in Use Example 1 except that the photosensitive resin composition of Example 2 was used in place of the photosensitive resin composition of Use Example 1 described above, and exposure and development were similarly performed. The volume phase hologram obtained by the reflection has a reflection diffraction efficiency of 99.9%, a transmittance of 92% and a haze of 1.6%.
Despite increasing by 0%, haze was comparable. or,
Also in the heat storage test, the same results as in Use Example 1 were obtained.

Comparative Example 1 PVCz (Rubican M-170) before purification in Example 1
A recording layer was formed, exposed to light and developed in the same manner as in Use Example 1 except that, to obtain a volume phase hologram of Comparative Example. When this hologram was measured in the same manner as in Use Example 1, the diffraction efficiency was only 4% and the transmittance was 68%, which was clearly cloudy and there was no need to measure the haze value. Further, after the same heating test as in Use Example 1, diffraction was completely lost.

Further, in the above, the developing conditions were as follows: immersion in toluene at 20 ° C. for 2 minutes, immersion in xylene at 25 ° C. for 2 minutes, then immersion in heptane at 20 ° C. for 2 minutes, and development at low temperature,
The diffraction efficiency was 12% and the transmittance was 77%, and the diffraction efficiency disappeared after the heating test at 140 ° C. for 5 hours.

When the above PVCz before purification was measured under the same conditions as in Example 1, the weight average molecular weight was 920,000 and the molecular weight distribution was 5.
Was 4.

Comparative Example 2 In place of the purified PVCz used in Example 1, 2.5 g of unpurified PVCz (Tubicor 210SP, manufactured by Anan Fragrance Co., Ltd.) was used, and the other processes were performed in the same manner as in Example 1 except for forming a recording layer, exposing and Development was performed to obtain a volume phase hologram of Comparative Example. This hologram also has a maximum diffraction efficiency of 23% (520 nm), a transmittance of 73% and a haze of 21%, and the peak wavelength shifts to 501 nm after the heating test at 140 ° C for 5 hours, and the maximum diffraction efficiency becomes 6%. Fell.

When the above PVCz before purification was measured under the same conditions as in Example 1, the weight average molecular weight was 780,000 and the molecular weight distribution was 4.
Was 6.

Comparative Example 3 A photosensitive resin composition of Comparative Example was prepared in the same manner as in Example 1 except that the stabilizer was not used, and the change in viscosity with time of the solution was measured equally. Got The solution thickened to over 5,500 cps was difficult to homogenize even if diluted with a solvent, which made it difficult to use.

[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.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shogo Taniguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-49-6914 (JP, A) JP-A-SHO 54-101343 (JP, A) JP-A-2-3082 (JP, A) JP-A-53-15153 (JP, A) JP-A-60-258579 (JP, A) JP-A-60-222882 (JP, A) A) JP-A-62-275283 (JP, A) JP-B-45-24606 (JP, B1)

Claims (3)

(57) [Claims] 1. 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 are contained in an organic solvent at 20 ° C.
A photosensitive resin composition having a viscosity in the range of 50 to 5,000 cps. 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 stabilizer is one or more selected from the group consisting of benzophenone, quinone, hydroquinone, diphenylpicrylhydrazyl and derivatives thereof.