JPH0529101B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical recording medium that is capable of multiplex recording on the same location of the same material using light of different wavelengths by utilizing the photochemical hole burning phenomenon. .

[Conventional technology] The photochemical hole burning phenomenon is a method in which monochromatic light is irradiated onto a material that undergoes a photochemical reaction at an extremely low temperature similar to the temperature of liquid helium, and only guest molecules that absorb the light are selectively excited. ,
It causes photochemical changes. At this time,
Since sharp holes are formed in the absorption spectrum of the material, recording is possible depending on the presence or absence of holes. Furthermore, by sequentially recording while changing the wavelength of the irradiated light, wavelength multiplexing recording can be performed at the same location on the same material. Using this method,
It has the potential to improve recording density by approximately 1000 times compared to conventional optical digital recording media such as compact discs and laser discs.

Such a recording medium is composed of guest molecules, which are photoreactive compounds, and a host that disperses the guest molecules. In order to increase the wavelength multiplicity of recording, an amorphous host with diverse guest dispersion states is used. For example, there are materials in which the guest is tetraphenylporphine and the host is polymethyl methacrylate (Optics. 14 (4) 263-269), and the guest tetraphenylporphin is pendant on poly(t-butylmethacrylamide). Type (second
(Figure) (Japanese Unexamined Patent Publication No. 188405/1983)
etc. are known.

[Problems to be Solved by the Invention] However, the photochemical hole burning phenomenon has the disadvantage that it becomes unstable at temperatures higher than the liquid helium temperature, making writing, saving, and reading of records uncertain. . This is because the guest tetraphenylporphin changes its position and orientation in the host polymethyl methacrylate when the temperature is higher than the liquid helium temperature. In an attempt to suppress this change, JP-A-60-
Publication No. 188405 develops a material in which a host and a guest are bonded in a pendant shape, but since there is only one bonding point, this change cannot be sufficiently suppressed.

The present invention aims to solve the drawbacks of the prior art, and by making porphine, which is a photoreactive guest, into a cross-linked type that bonds with the host polymer at two or more points, it can be heated at temperatures higher than the temperature of liquid helium. The purpose of the present invention is to provide a cross-linked porphine-based PHB optical recording medium that suppresses irreversible changes and has high recording stability.

[Means for Solving the Problems] The present invention has the following configuration to achieve the above object.

"A porphyne derivative having two or more olefinic double bonds and represented by the following general formula [A],
A crosslinked porphyrin system characterized by being copolymerized with a compound having an olefinic double bond.
PHB optical recording medium.

(However, at least two of R ₁ to _{R 4} in the formula have an olefinic double bond.) First, as a porphyne derivative represented by the general formula [A], among R ₁ to _{R 4} , At least two are
Any compound having an olefinic double bond may be used, but from the viewpoint of reactivity with a compound having an olefinic double bond, at least two of R ₁ to _{R 4} are -NHCOC( It is preferable that it is at least one selected from _CH2 )= _{CH2 - CO2CH2PhCH} = _CH2 . This porphin derivative has two to
Since it has four olefinic double bonds, it acts as a crosslinking agent when copolymerized with a compound having an olefinic double bond by radical polymerization or cationic polymerization. In this polymer, since the porphin molecules are bonded to the polymer main chain at 2 to 4 points, rotation and changes in orientation of the porphin molecules, which are photoisomerizable molecules, are suppressed. Therefore, the thermal stability of the formed holes is improved.

Examples of methods for synthesizing such porphin derivatives include reactions represented by the following formulas (B) and (C).

Next, as the compound having an olefinic double bond, methacrylic esters and styrene are preferable since the resulting polymer has excellent transparency and moldability, and acrylic esters,
Any material that can be copolymerized with a porphine derivative such as vinyl acetate, acrylonitrile, vinylidene chloride, N-vinylpyrrolidone, and vinylpyridine may be used.

In this copolymer, the concentration of porphine, which is a crosslinked structure, is determined by the molar ratio of monomers, that is,
The molar ratio of the porphyne derivative to the compound having an olefinic double bond is preferably 1:100 to 1:1,000,000. This is because if the concentration is too high, the hole generation characteristics will deteriorate due to energy transfer between porphin molecules, and if the concentration is too low, the S/N ratio during recording and reading will become small.

[Example] The present invention will be described in more detail based on Examples below, but the present invention is not limited thereto.

Example 1 25 g (0.15 mol) of p-acetaminobenzaldehyde and 10.3 g (0.15 mol) of p-acetaminobenzaldehyde and 10.3 g (0.15 mol) of pyrrole were added to 600 ml of refluxed propionic acid. After further refluxing for 30 minutes, the precipitate precipitated was filtered and -acetaminophenyl)porphin was obtained. The yield is
The yield was 4.2% at 2.7g.

After refluxing 1.55 g of the obtained product in 200 ml of concentrated hydrochloric acid for 6.5 hours, it was neutralized with aqueous ammonia, and further,
Extracted with chloroform. The product was purified by column chromatography to obtain 0.62 g of tetra(p-aminophenyl)porphine in a yield of 51%. In the infrared absorption spectrum, 3600 is the characteristic absorption of amino groups.
The structure was confirmed by showing an absorption of ~3300 cm ^-1 .

Tetra(p-aminophenyl) obtained from the above reaction
Dissolve 0.2 g of porphyne in 50 ml of dry acetone, add 1 ml of methacryloyl chloride and 1 ml of pyridine.
was added and reacted at room temperature for 1.5 hours. It was purified by chloroform extraction and column chromatography to obtain tetra(p-methacryloylaminophenyl)porphin. Yield is 15 mg, yield is 5.3
It was %. The structure was confirmed by an infrared absorption spectrum showing absorption at 1660 cm ^-1 , which is the characteristic absorption of an amide group.

Furthermore, a tetrahydrofuran solution containing 5 x 10 ^-1 mol of tetra(p-methacryloylaminophenyl)porphine, 20 g of methyl methacrylate
(0.2 mol), 100 mg of azobisisobutylnitrile and 20 ml of methyl ethyl ketone were degassed and heated at 60°C.
Polymerization was carried out for 20 hours. Porufin has a cross-linked structure
PMMA was obtained in a yield of 10.9 g and a yield of 55%. The presence of a crosslinked structure in this polymer was confirmed from the fact that the highly polymerized component contained a large amount of porphine skeleton.

At a temperature of 4.2 K, this polymer has a power output of 1 mw/cm ² ,
Photochemical holes were formed by irradiation with laser light with a wavelength of 650 nm for 1.5 minutes. When this hole was subjected to the temperature cycle shown in FIG. 3, the half width of the hole showed an increase as indicated by the circle in FIG. 4. In FIG. 3, the x mark indicates laser irradiation, and the ○ mark indicates half-width measurement of the hole. The graph in Figure 4 shows the half-width (〓 _T ) of the hole measured after heating up to the heating temperature TK and then recooling.
The value obtained by subtracting the half-width of the hole at the time of hole formation (〓 _4.2 ) is plotted. Measurements were continued until the holes disappeared.

Comparative example 1 Polymethyl methacrylate (degree of polymerization = 400000)
After dissolving 10g in 120ml of toluene, 5, 10,
61 mg of 15,20-tetraphenylpolyphine was added. By drying this solution in a shear dish, a film having a guest concentration of 10 ^-2 M and a thickness of 0.5 mm was prepared, which was used as a control sample. The temperature dependence of the increase in the half-width of the hole measured in the same manner as in Example 1 is shown by the black circle in FIG.

Comparing Example 1 and Comparative Example 1 in FIG. 4, the half width of the hole increases as the heating temperature increases, whereas in Comparative Example 1, the hole disappears at 45K or higher. In Example 1, the amount of increase in half width was small, and holes were observed up to 80K. That is, it can be seen that the crosslinked structure improved the thermal stability of the holes.

Example 2 30 g (0.2 mol) of p-carboxybenzaldehyde and 13.4 g of pyrrole in 750 ml of refluxed propionic acid
(0.2 mol) was added, the mixture was refluxed for an additional 30 minutes, and then filtered to obtain 6.9 g (yield: 4.3%) of tetra(p-carboxyphenyl)porphine. The structure was confirmed by an infrared absorption spectrum showing absorption at 3600-2500 and 1690 cm ^-1 , which is characteristic of carboxylic acids.

1 g (1.27 mol) of this tetra(p-carboxyphenyl)porphin was added to 20 ml of dimethylformamide.
1.5g of chloromethylstyrene dissolved in
(10.5 mmol) and triethylamine 10.5 g
(10.5 mmol) was added and reacted at 90°C for 7 hours. The reaction mixture was extracted with chloroform to give 0.83 g (yield
52%) of tetra(p-(vinylbenzyloxycarbonyl)phenyl)porphine crystals were obtained.
Infrared absorption spectrum of 1720 cm ^-1 , which is unique to esters.
The structure was identified from the absorption of .

33 mg (0.026 mmol) of this porphyne derivative having an olefinic double bond, 20 ml of styrene
(0.17mol) Neazobisisobutyronitrile 150mg
After mixing and 100ml of benzene, degas and heat at 60℃.
Polymerization was carried out for 20 hours to obtain 6.7 g (36.8%) of polystyrene having a crosslinked structure of porphine. The presence of a crosslinked structure in this polymer was confirmed from the fact that the highly polymerized component contained a large amount of porphine skeleton.

At a temperature of 4.2 K, this polymer has a power output of 1 mw/cm ² ,
Photochemical holes were formed by irradiating laser light with a wavelength of 650 nm for 1.5 minutes. When this hole was subjected to the temperature cycle shown in FIG. 3, the half width of the hole increased as shown by the curve connecting the black circles in FIG. 5.

Example 3 A tetrahydrofuran solution containing 5 x 10 ^-5 mol of tetra(p-methacryloylaminophenyl)porphine synthesized according to the same method as in Example 1,
15 g of bornyl methacrylate, 100 mg of azobisisobutyronitrile, and 20 ml of methyl ethyl ketone were mixed and polymerized at 60° C. for 20 hours. Polybornyl methacrylate having porphyne at the crosslinking point,
Obtained in a yield of 12.1 g and a yield of 81%. The presence of a crosslinked structure in this polymer was confirmed from the fact that the highly polymerized component contained a large amount of porphine skeleton.

At a temperature of 4.2 K, this polymer has a power output of 1 mw/cm ² ,
Laser light with a wavelength of 650 nm was irradiated for 1.5 minutes to form photochemical holes. When this hole was subjected to the temperature cycle shown in FIG. 3, the half width of the hole showed an increase as shown by the curve connecting the circles in FIG.

Example 4 A tetrahydrofuran solution containing 5 x 10 ^-5 mol of tetra(p-methacryloylaminophenyl)porphine synthesized according to the same method as in Example 1,
15 g of octyl methacrylate, 100 mg of azobisisobutyronitrile and 20 ml of methyl ethyl ketone were mixed and polymerized at 60° C. for 20 hours. Polyoctyl methacrylate having porphyne at the crosslinking point,
Obtained in a yield of 12.5 g and a yield of 83%. The presence of a crosslinked structure in this polymer was confirmed from the fact that the highly polymerized component contained a large amount of porphine skeleton.

At a temperature of 4.2 K, this polymer has a power output of 1 mw/cm ² ,
Laser light with a wavelength of 650 nm was irradiated for 1.5 minutes to form photochemical holes.

[Effects of the Invention] Since the wavelength multiplexing recording medium of the present invention has photoisomerizable molecules at the crosslinking points of the polymer, it has increased thermal stability compared to conventional wavelength multiplexing recording media, and the hole resistance after increasing the temperature increases. The recovery rate will be very high.

[Brief explanation of the drawing]

FIG. 1A shows a model of a polymer having a porphine having four olefinic double bonds at a crosslinking point according to the present invention. FIG. 1B shows a model of a polymer having porphine having three olefinic double bonds at the crosslinking point of the present invention. FIG. 1C shows a model of a polymer having a porphine having two olefinic double bonds at a crosslinking point according to the present invention. FIG. 2 shows a model of one embodiment of a polymer in which a porphine derivative having one olefinic double bond is used. In the drawings, 1 represents porphin and 2 represents the main chain. FIG. 3 shows a temperature cycle for evaluating the thermal stability of the sample. The solid line indicates the change in sample temperature, the x mark indicates laser irradiation, and the ○ mark indicates the half-width measurement of the hole. FIG. 4 shows the amount of increase in the half-width of holes when a temperature cycle is applied to evaluate thermal stability for Example 1 and Comparative Example 1. FIG. 5 shows the amount of increase in the half-width of holes when temperature cycles were applied to the samples of Examples 2 and 3 to evaluate thermal stability.

[Claims]

1. Photopolymerizable printing elements or printing plates for flexographic printing containing thermoplastic elastomeric block copolymers with polymer blocks of polystyrene and polyisoprene and/or polybutadiene or copolymers thereof as elastomeric binder. The printing plate is subjected to a step of imagewise exposure of said photopolymerizable printing element, removal of unexposed areas, optional chemical post-treatment, and subsequent non-imagewise post-exposure to join the edges of the printing plate together. and (a) making smooth and precise corresponding diagonal cuts in the photopolymerizable printing elements or printing plates to be joined together at the edges to be joined together, and b making the cuts to be joined together. a linear polystyrene-polybutadiene-polystyrene and/or polystyrene-polyisoprene-polystyrene block copolymer having a weight average molecular weight (w) of at least 80,000, at least one photopolymerizable ethylenically unsaturated monomer; , photoinitiator or photoinitiator system, and as a single solvent.

Claims (1)

has an olefinic double bond. ) 2 At least two of R ₁ to R ₄ are at least one selected from -NHCOC(CH ₃ )=CH ₂ —CO ₂ CH ₂ PhCH=CH ₂ 2. The crosslinked porphyrin-based PHB optical recording medium according to item 1. 3. The crosslinked porphin-based PHB optical recording medium according to claim 1, wherein the porphin derivative has four olefinic double bonds. 4. The crosslinked porphyrin-based PHB optical recording medium according to claim 1, wherein the compound having an olefinic double bond is a methacrylic acid ester or styrene. 5 The molar ratio of the porphyne derivative to the compound having an olefinic double bond is 1:100 to 1:
1,000,000. The crosslinked porphyrin-based PHB optical recording medium according to claim 1, wherein the optical recording medium has a molecular weight of 1,000,000.