JPH0219942B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel optical recording medium and its material,
More specifically, the present invention relates to an optical recording medium using a photosensitive polymer having a cinnamylidene group in its side chain, its material, and a method for forming an optical recording medium from the material. Phase-type optical recording bodies, particularly phase-type hologram memory bodies, which record optical signals by utilizing a change in refractive index caused by light irradiation, have high light utilization efficiency because there is little loss due to absorption of light during readout. Taking advantage of this excellent property, many applications have been proposed for general memories, hologram displays, etc. Examples include single crystals such as lithium niobate, amorphous inorganic thin film materials such as chalcogenite films, and photopolymer materials such as gelatin, sensitized polymethyl methacrylate, or photopolymerizable acrylate compositions. Among these, since photopolymer films can be made to have a large area, there is a strong desire to develop phase-type optical recording materials using photopolymers. However, since there is no optical recording material that satisfactorily combines basic characteristics such as sensitivity, resolution, diffraction efficiency, and storage stability, it has not yet been put into practical use. The present inventors focused on the fact that cinnamic acid-based polymers, which have been put into practical use as photosensitive resins for resists and lithography, crosslink due to photodimerization reactions, and as a result of intensive research to apply them as optical recording materials, they discovered that polyvinyl thinner By crosslinking mylidene acetates by irradiation with ultraviolet and visible laser beams,
The present invention was achieved by discovering that a phase-type optical recording image can be formed while the refractive index changes with high sensitivity and the transparency is maintained as a whole. That is, the present invention has the following general formula [] [However, in the formula, R ₁ represents a hydrogen atom, a methyl group, a phenyl group, a phenoxy group or a cyano group,
R ₂ represents a hydrogen atom, a methyl group or a phenyl group. X is

[Formula] or

Represents a group represented by [Formula]. ] A phase-type optical recording material comprising a photosensitive polymer having a cinnamylidene group in its side chain, which is represented by the following formula, laminated on a substrate as a refractive index distribution recording layer, 2. [However, in the formula, R ₁ represents a hydrogen atom, a methyl group, a phenyl group, a phenoxy group or a cyano group,
R ₂ represents a hydrogen atom, a methyl group or a phenyl group. X is

[Formula] or

Represents a group represented by [Formula]. ] A photosensitive polymer having a cinnamylidene group in its side chain represented by is crosslinked non-uniformly or in a distributed manner,
A phase-type optical recording medium formed with a crosslinked polymer layer having a refractive index distribution, and 3. The following general formula [] [However, in the formula, R ₁ represents a hydrogen atom, a methyl group, a phenyl group, a phenoxy group or a cyano group,
R ₂ represents a hydrogen atom, a methyl group or a phenyl group. X is

[Formula] or

Represents a group represented by [Formula]. ] A phase characterized in that a polymer having a cinnamylidene group represented by the following in its side chain is used as a refractive index distribution recording layer, the layer is crosslinked by laser irradiation, and a refractive index distribution corresponding to the irradiated laser intensity distribution is recorded. This is a method for manufacturing a molded optical recording medium. In the present invention, R ₁ of the cinnamylidene group represented by the above formula [] is a hydrogen atom, a methyl group, a phenyl group, a phenoxy group, or a cyano group, and R ₂
is a hydrogen atom, a methyl group or a phenyl group, and
teeth

[Formula] or

[Formula]. X is

In the case of [Formula], cinnamylidene acetyl groups and

In the case of [Formula], it becomes a cinnamylidenepyruvyl group. Among these, cinnamylidene acetyl group (R ₁ = H, R ₂ = H,

[Formula]), α-methylcinnamylideneacetyl group (R ₁ = CH ₃ , R ₂ = H,

[Formula]), α,γ-dimethylcinnamylideneacetyl group (R ₁ = CH ₃ , R ₂ = CH ₃ ,

[Formula]), α-phenylcinnamylideneacetyl group (

[Formula] R ₂ = H,

[Formula]), α-cyanocinnamylideneacetyl group ((R ₁ = CN,
R ₂ =H,

[Formula]) and cinnamylideneacetyl groups and cinnamylidenepyruvyl groups (R ₁ =
H, R ₂ = H,

[Formula]), γ-methylcinnamylideneacetyl group (R ₁ = H, R ₂ = CH ₃ ,

[Formula]) is preferably used, and cinnamylideneacetyl group, α-cyanocinnamylideneacetyl group and cinnamylidenepyruvyl group are particularly preferably used. Examples of the backbone polymer of the photosensitive polymer in the present invention, that is, the polymer to which the group represented by the formula [] is bonded include polyvinyl alcohol, phenoxy resin, polyvinylphenol, polyvinylbenzyl alcohol, polyhydroxyethyl vinyl ether, polyhydroxyethyl It is a polymer having a hydroxyl group such as (meth)acrylate or polyhydroxypropyl (meth)acrylate. Suitable polymers include polyvinyl alcohol, phenoxy resin, polyhydroxyethyl vinyl ether, and the like. Of course, the cinnamylidene group represented by the above formula [] in the side chain is bonded to the hydroxyl group of the backbone polymer through an ester bond. Such photosensitive polymers can be produced industrially by dehydrochlorination reaction of the corresponding active derivatives of cinnamylidene acetic acids or cinnamylidene pyruvic acids, such as acid chloride, and the backbone polymer in pyridine, or by Schotten-Baumann reaction. is possible. It is also possible to obtain the monomer by introducing a side chain group represented by the above formula [] into the monomer in advance and then polymerizing it by a radical polymerization method or a cationic polymerization method. In principle, the phase-type optical recording material of the present invention is one in which the above-mentioned polymer is laminated on a substrate as a refractive index distribution recording layer, but of course, in a special form, only the above-mentioned polymer itself is used without using a substrate. It is also possible. The refractive index distribution recording layer can be made of only the above polymer, but a sensitizer may be added for the purpose of improving sensitivity or expanding the sensitive wavelength range to the long wavelength visible laser range. preferable. Such sensitizers include acridone sensitizers such as N-phenylthioacridone and N-phenyl-3-nitrothioacridone; xanthene dyes such as rhodamine B, erythrosin, and eosin; thiomihirazketone, Michler's ketones such as Michler's ketone; 2,4,6-triphenylpyrylium perchlorate, 4-anisyl-
2,6-biphenylpyrylium perchlorate,
4-(4-amyloxyphenyl)-2,6-bisanisylpyrylium perchlorate, 4-(4-
pyrylium salts such as amyloxyphenyl)-2,6-bisanisylthiapyrylium perchlorate;
In addition, rose bengal, 9,10-phenanthroquinone, 5-nitroacenaphthene, benzanthracene and the like are preferably used. Among these, N-phenylthioacridone, rose bengal, erythrosin, eosin, benzanthracene, 4-(4-amyloxyphenyl)-2,6-bisanisylpi Particularly preferred are lylium perchlorate, 4-(4-amyloxyphenyl)-2,6-bisanisylthiapyrylium, and perchlorate. Of course, these may be used alone or in combination. The amount of sensitizer used depends on the purpose of sensitization, compatibility with the photosensitive polymer, and solubility in the solvent used when forming a film using a solvent. 0.01% by weight for combined
It is used in a range of 20% by weight, preferably 0.1% by weight to 15% by weight. If it is less than that, the sensitizer will not be effective and its addition will be meaningless, and if it is more than that, the sensitizer will precipitate, causing undesirable scattering, or absorption in the surface layer will prevent light from reaching the interior. Undesirable. The substrate on which the above materials are laminated is preferably an organic or inorganic film, sheet, or plate substrate, such as an organic polymer film, sheet, or glass plate, and a transparent substrate is preferable for holographic applications. preferable. The thickness of the refractive index distribution recording layer varies depending on the purpose of use, but it is required to be 0.01 μm or more in order to obtain an effective phase change as a phase-type optical recording material, and to further increase the S/N ratio during readout. The film thickness is preferably 1 μm or more. There is no particular upper limit to the film thickness, but generally about 1 mm is sufficient. As for the lamination method of such a refractive index distribution recording layer, any conventionally known lamination method may be selected and adopted as appropriate; for example, the material may be dissolved in a suitable solvent, applied onto a substrate, and the solvent removed by drying. This can be easily achieved. The solvent used is not particularly limited as long as it dissolves the polyvinyl cinnamylidene acetate and the sensitizer added if necessary. High-boiling polar solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, hexamethylphoforamide, and tetramethylurea, cyclohexanone,
Ketones such as methyl ethyl ketone and methyl isobutyl ketone, ethers such as ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, and dioxane,
and mixtures thereof are preferred. The coating method and drying conditions are not particularly limited. The novel phase-forming optical recording material of the present invention causes a refractive index change of about 1/1000 when optical information is written.
This change is a sufficient property to store information in the form of a phase change. Surprisingly, in the optical recording material of the present invention, almost no increase in scattering noise is observed even when optical information is written. This characteristic indicates that it has an excellent signal-to-noise ratio (S/N) as a phase-type optical recording material. Considering the fact that the polymethyl methacrylate material sensitized with p-benzoquinone exhibits a decrease in S/N due to a large increase in scattering noise as the exposure amount increases, it is effective as a phase forming material for the optical recording material of the present invention. The gender is obvious. It is thought that the reaction that occurs when optical information is written is due to light dimerization, and that the above characteristics are obtained because distortion in the medium that causes scattering noise is less likely to occur. This characteristic suggests that an extremely excellent S/N ratio can be obtained when the multiplicity of the volume hologram using the information capacity in the thickness direction of the medium is increased. The phase-forming optical recording material of the present invention exhibits excellent properties for use in general optical memories, hologram displays, hologram interference measurements, and the like. The optical signal is provided in bit, high bit or holographic form. The novel phase recording material of the present invention has sensitivity in the wavelength range from ultraviolet to visible. In particular, depending on the combination with a sensitizer, it has high sensitivity to light of 600 mμ or less. Sensitive to various lasers such as dye lasers, _N2 lasers, Kr ion lasers, He-Cd lasers, Ar ion lasers, He-Ne lasers, harmonics of Nd glass lasers, and Rupee lasers, especially Kr ion lasers and Ar ion lasers. By using an etalon such as a laser, it has high sensitivity to laser light, which is suitable for storing holographic information. For example, by combining with an appropriate sensitizer, the 514 mμ light of an Ar ion laser can be
It has more than 10 times the sensitivity of polymethyl methacrylate sensitized with p-benzoquinone. As described above, the phase-type optical recording material described in detail can cause a crosslinking reaction depending on the irradiation intensity by irradiating the refractive index distribution recording layer with laser light, regardless of the presence or absence of a substrate. , thereby making it possible to obtain a phase-type optical recording medium having a distribution in refractive index. Polycinnamylidene acetate itself is used, for example, in photoresists, and it is known that it crosslinks when irradiated with light. It was not known that the refractive index could change enough to form a body.
Furthermore, since the phase-type optical recording medium of the present invention uses a specific crosslinked polymer, it is characterized by low noise during reading. For example, as can be understood from FIGS. 3 to 6 of the accompanying drawings, the phase-type optical recording medium of the present invention has a sharper readout compared to the polymethyl methacrylate-based phase-type optical recording medium. Although it is difficult to clearly specify the structure of the crosslinking reaction caused by laser irradiation of the polymer constituting the phase-type optical recording material of the present invention, as mentioned above, cinnamylidene represented by the above formula [] It is presumed that the groups undergo a photodimerization reaction and are crosslinked. The phase recorder may be irradiated with an optical signal. Even if the entire surface is irradiated as such post-processing, the initially formed refractive index distribution record will not disappear. The present invention will be further explained below with reference to Examples. Example 1 9.1 parts of erythrosine was added as a dye sensitizer to 100 parts of polyvinyl cinnamylidene acetate corresponding to R ₁ =H, R ₂ =H in the above formula [].
Dissolve in 1000 parts of dimethylacetamide. The solution was applied onto a 2 mm thick glass plate using a doctor knife to form a film. Drying at 40℃ under 1mmHg vacuum.
I went there for 10 hours. The film thickness was 150 μm. An Ar ion laser with a wavelength of 514.5 mμ was incident perpendicularly to the film surface at an incident angle of ±6° using two-beam interferometry to create a phase-type diffraction grating in the film. The Ar ion laser was used with a beam diameter of 2 mm and an output adjusted to 5 mW. For reading, the diffraction efficiency was measured using 632.8 mμ light from a He--Ne laser, which was incident at a black angle. The beam diameter was 0.8 mm and the output was adjusted to 0.05 mW. By irradiation with an exposure dose of 100mJ/ ^cm2 , 1%,
A diffraction efficiency of 5% was obtained at an exposure dose of 500 mJ/cm ² and 20% at an exposure dose of 1 J/cm ² . Although the exposure amount was further increased to 250 J/cm ² , no increase in scattering noise was observed. Example 2 In the above formula [], 100 parts of polyvinyl cinnamylidene acetate corresponding to R ₁ = H, R ₂ = H and 5 parts of erythrosine as a dye sensitizer were added to 1000 parts.
of dimethylformamide. The solution was applied using a doctor knife onto a biaxially stretched polyethylene terephthalate film having a thickness of 75 μm.
Drying at 100℃ for 30 minutes under reduced pressure of 1 mmHg, followed by 40 minutes
℃ for 15 hours. The film thickness was 50 μm. A diffraction grating was written on the film in the same manner as in Example 1, and the diffraction efficiency was measured. A diffraction efficiency of 1% was obtained at an exposure dose of 150 mJ/cm ² and 7% at an exposure dose of 1 J/cm ² . Example 3 In the above formula [], 100 parts of polyvinyl cinnamylidene acetate corresponding to R ₁ =H, R ₂ =H and 1.1 parts of eosin yellow as a dye sensitizer were added.
Dissolved in 1000 parts of dimethylacetamide. The solution was applied onto a 2 mm thick glass plate using a doctor knife to form a film. Drying at 100℃30 under a reduced pressure of 1mmHg
The temperature was then maintained at 40°C for 10 hours. Film thickness is 400μm
It was hot. Using a Kr ion laser with a wavelength of 530.9 mμ, the resolution pattern of the photograph was recorded as a Raunhofer-shaped hologram. The diffraction efficiency was 1%. Next, the reference beam was shifted by 1° and 20 multiplexed holograms were recorded in the film. Even with this multiplexing, no increase in scattering noise was observed. Example 4 In the above formula [], 100 parts of polyvinyl (α-cyano-cinnamylidene acetate) corresponding to R ₁ =CN, R ₂ =H and 4-(4-amyloxyphenyl)-2,6- 8 parts of bisanisylthiapyrylium perchlorate were dissolved in 1000 parts by weight of dimethylacetamide. Film formation and drying were performed in the same manner as in Example 1. The film thickness was 100 μm. A diffraction grating was prepared using the same method as in Example 1, and the diffraction efficiency was measured. As a result, a diffraction efficiency of 1% at 90 mJ/cm ² and 25% at 2.5 J/cm ² was obtained. Example 5 In the above formula [], 100 parts of polyvinyl (α-methyl-cinnamylidene acetate) corresponding to R ₁ =CH ₃ , R ₂ =H and 8 parts of N-phenylthioacridone were added to 1000 parts of dimethylacetamide. Dissolved. Film formation and drying were performed in the same manner as in Example 1.
The film thickness was 80 μm. A phase-type diffraction grating was prepared in the same manner as in Example 1, and the diffraction efficiency was measured. As a result, a diffraction efficiency of 1% at 250 mJ/cm ² and 7% at 2.5 J/cm ² was obtained. Example 6 The backbone polymer shown in the following formula was composed of 100 parts of a photosensitive polymer in which a cinnamylidene pyribyl group was introduced into the hydroxyl group of a phenoxy resin obtained from bisphenol-A diglycidyl ether and 4-(4-acyloxyphenyl ether). A film was formed from 10 parts of enyl)-2,6-bisanisylthiapyrylium perchlorate in accordance with the method of Example 1. The film thickness was 100 μm. Using this material, a phase-type diffraction grating was created in the same manner as in Example 1, and the diffraction efficiency was measured.
A diffraction efficiency of 1% at 400 mJ/cm ² and 7% at 1 J/cm ² was obtained. Example 7 A coating film of 100 parts of a pinyloxyethyl, α-cyanocinnamylidene acetate polymer represented by the following formula and 10 parts of thiomihirazketone was prepared according to the method of Example 1. The film thickness was 100 μm. A phase-type diffraction grating was created using this material in the same manner as in Example 1, and the diffraction efficiency was measured.
Diffraction efficiencies of 0.7% at 400 mJ/cm ² and 6% at 1 J/cm ² were obtained. Example 8 A phase type optical recording material was prepared in which a 100 μm film of polyvinylcinnamylidene acetate-erythrosine and a 200 μm film of PMMA-p-benzoquinone were respectively provided on glass plates. (A) Using these, writing was performed by uniform exposure as shown in FIG. 1a. Writing is Ar ⁺
Ion laser (uses 10mW light with a wavelength of 514.5nm, beam diameter is 2mm, and is approximately 1.5° from the axis perpendicular to the sample)
It was incident at an angle. Exposure time was 300 seconds. Thus, using the written sample, the first
As shown in Figure b, a He-Ne laser (wavelength
632.8 nm) was incident perpendicularly to the sample, readout was performed, and a photograph was taken. The beam diameter is 0.8mm.
On the other hand, a sample that had not been exposed or written with the Ar ⁺ ion laser was similarly irradiated with the He--Ne laser and photographed. Figure 3 shows the results for PMMA-p-benzoquinone samples, with (a) being a photograph of a sample that has not been exposed (written), and (b) being a photograph of a sample that has been written. FIG. 4 shows similar results for polyvinylcinnamylidene acetate-erythrosine based samples according to the present invention. (B) Using the sample described above, a diffraction grating was prepared by the method shown in FIG. 2a. Writing is performed using two-beam interferometry (5 mW x 2, incident angle ±6°) using an Ar ⁺ ion laser (wavelength 514.5 nm), and the exposure time is
It was hot in 60 seconds. Using the thus recorded sample, reading was carried out in the manner shown in FIG. 2b. Reading is
A He--Ne laser (wavelength: 632.8 nm) was incident on the diffraction grating at a Bragg angle. The 0th order light (directly traveling light) and the 1st order diffracted light were projected onto a screen and photographed.
FIG. 5 shows the photographic results of a PMMA-p-benzoquinone-based sample, and FIG. 6 shows the photographic results of a polyvinylcinnamylidene acetate-erythrosine-based sample. In both cases, the left side is the 0th-order light, and the right side is the 1st-order diffracted light.

[Brief explanation of drawings]

FIG. 1 shows an optical system for uniform exposure/writing and reading thereof, and FIG. 2 shows an optical system for producing a diffraction grating and reading it. Figures 3 to 6 show the microstructures (microstructures) of PMMA-p-benzoquinone-based and polycinnamylidene acetate-erythrosine-based phase-based optical recording materials that have been subjected to phase-based optical recording to produce a refractive index distribution. ), which is expressed by uniform exposure and readout and holographic diffraction grating readout. Figure 3 shows PMMA - p-benzoquinone type, Figure 4 shows polycinnamylidene acetate -
FIG. 3 is a diagram of uniform exposure and readout of erythrosine. FIG. 5 is a read-out diagram of a PMMA-p-benzoquinone-based diffraction grating, and FIG. 6 is a read-out diagram of a polycinnamylidene acetate-erythrosine-based diffraction grating.

Claims (1)

[Claims] 1. The following general formula [] [However, in the formula, R ₁ represents a hydrogen atom, a methyl group, a phenyl group, a phenoxy group or a cyano group,
R ₂ represents a hydrogen atom, a methyl group or a phenyl group. X represents [Formula] or a group represented by [Formula]. ] A phase type optical recording material comprising a photosensitive polymer having a cinnamylidene group in its side chain, which is laminated on a substrate as a refractive index distribution recording layer. 2 General formula below [] [However, in the formula, R ₁ represents a hydrogen atom, a methyl group, a phenyl group, a phenoxy group or a cyano group,
R ₂ represents a hydrogen atom, a methyl group or a phenyl group. X represents [Formula] or a group represented by [Formula]. ] A phase characterized in that a polymer having a cinnamylidene group represented by the following in its side chain is used as a refractive index distribution recording layer, and the layer is crosslinked by laser irradiation to record a refractive index distribution corresponding to the irradiated laser intensity distribution. A method for manufacturing a molded optical recording medium.