JP2000264962A - Photoreactive polyester, its production and optical recording medium using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject polyester having a rapid optical recording velocity without damaging optical recording characteristics, excellent in memory, modulation factor, and the like, and useful as a material for holographic recording media by using an alkyl having a specific carbon number in its main chain. SOLUTION: This invention is to obtain a photoreactive polyester expressed by formula I [(m) is 2-18; (l) is 8 or 10; W is an ether bond, a thioether bond, a substituted imino bond, or the like; (n) is 5-500]. The polyester expressed by formula I is obtained by reacting a photoresponsive dicarboxylic acid monomer expressed by formula II (X is a lower alkyloxy, benzyloxyy, or the like) with a diol compound expressed by formula III in the presence of a suitable catalyst. E.g. a polyester of formula IV in which (m) is =6, is synthesized from diethyl (5- 6-[4'-4"-cyano-phenylazo)phenoxy}hexyloxy)-isophthalate and 4,4'-bis[8- hydroxyoctyloxy]-diphenyl ether.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a photoreactive resin suitable as an optical recording medium material for recording a large amount of data information,
And a method of manufacturing the same, and an optical recording medium manufactured using the same.

[0002]

2. Description of the Related Art Rewritable optical disk storage devices of the phase change type, the magneto-optical type and the like are already widely used. These optical disk devices achieve high-capacity storage by increasing the recording density by at least one order of magnitude compared to general magnetic disk devices.However, the capacity of operating systems (OS) and application software has become higher due to higher functionality. It has sufficient performance for future large-capacity recording requirements such as increase in capacity, huge capacity due to multi-media of various documents and presentation data, digital recording of high-definition, high-density, long-time moving image video signal etc. I can not say.

In the current high-density and large-capacity optical disk storage device, in order to increase the recording density, a device such as reducing the beam spot diameter and shortening the distance between adjacent tracks or adjacent bits is used. However, since the above-mentioned optical disc records data in a plane,
Physical limit of high-density recording limited by the diffraction limit of light (5 Gbit
/ in ² ) is approaching, and in order to further increase the capacity, three-dimensional (volume type) recording including the depth direction is required.

[0004] As the above-mentioned volume type optical recording medium, a wavelength division multiplexing storage medium using a laminated body which is independently sensitive to a plurality of wavelengths, or a photorefractive material medium (photorefractive material) capable of volume recording a hologram grating. Material media) are promising. Some photorefractive materials, which have a high sensitivity and absorb a relatively weak light of a solid-state laser level and cause a change in the refractive index, are known. It is expected to be used.

[0005] As this photorefractive material,
Conventionally, inorganic ferroelectric crystals such as barium titanate, lithium niobate, and BSO have been widely used. Although these materials exhibit high sensitivity and high efficiency photo-induced refractive index change effect (photorefractive effect), it is difficult to grow crystals in many cases.Because there are many hard and brittle materials, they cannot be processed into any shape. There were drawbacks such as difficulty in adjusting the sensitive wavelength.

In recent years, a photorefractive material (hereinafter, sometimes referred to as a PR material) made of an organic material has been proposed to overcome these disadvantages. Compounds A to D represented by the following structures are components of a typical organic photorefractive material.

In general, organic photorefractive materials are:
i) a charge-generating material that receives light to generate charges, ii) a charge-transfer material that facilitates the transfer of the generated charges in a medium, iii) a dichroic organic dye that is sensitive to an electric field induced by charge transfer, iv) a polymer base material (binder) that supports these materials, and v) an additive (plasticizer,
Compatibilizer, etc.). Some of these components play multiple roles, such as a charge transfer material / polymer substrate and a charge transfer material / plasticizer. Here, compound A (2,4,7-trinitrofluorenone (TNF)) is a charge generating material and compound B (poly
(Vinyl carbazole) (PVK)) is a charge transfer material and polymer base material (binder), compound C (N-ethyl carbazole (ECz)
Is a charge transfer material and plasticizer, compound D (2,5-dimethyl-4- (4 '
-Nitrophenyl) -azoanisole (DMNPAA)) functions as a dichroic organic dye.

Embedded image Figure 1 shows the mechanism of refractive index change induced by light irradiation
Shown in The principle of the photorefractive effect is to irradiate a PR material with two coherent light waves to form interference fringes I (x).
At a place where the light intensity is high, electrons at the donor level are excited into the conduction band, move by diffusion or drift, and are captured at a place where the light intensity is weak. Positive charges remain in places where the light intensity is strong, and negative charges accumulate in places where the light intensity is weak. This forms a charge distribution ρ (x), producing an electrostatic field E (x). As a result of the electro-optic effect due to this electrostatic field, the refractive index change Δn
(x) results. The period of this refractive index change is the same as the period of the interference fringes, and this refractive index grating acts as a hologram diffraction grating. By such an action, positive and negative charges are generated from the charge generating material that has absorbed the light, and are separated into positive and negative by the charge transfer agent by the action of an external field where the charge is present, thereby generating an internal electric field. Due to this internal electric field, the orientation of the dichroic dye changes, and the distribution of the refractive index in the substrate changes.

By using this method, Meerholz et al. Of the University of Arizona have succeeded in developing a material exhibiting diffraction efficiency [Nature, 371, 497 (1994)]. It was thought that, by applying such a material, volume hologram storage with a high storage density was possible in principle.

On the other hand, since this material essentially uses the orientation of the dye due to an external electric field and its change due to light irradiation as a recording mechanism, there is a problem that the application of an external electric field is indispensable at the time of use. is there. This electric field is as large as several hundred V · mm ⁻¹ in the previous study by Meerholz et al., Which is a major device restriction when actually using this system as a storage device. Furthermore, in this material system, several kinds of different materials such as a charge generating material, a charge transfer agent, and a polymer substrate are mixed and used, so that a decrease in stability due to phase separation during recording or storage is a major problem. Become.

In order to avoid the above problems, for example, S.
Hvilsted et al. Have proposed using a polymer material represented by the following compound E having liquid crystal forming properties to achieve recording by writing a refractive index grating here [Opt. Let
t., 17 [17], 12 (1992)]. Figure 3 shows the material system they use. In this material, for example, it has been revealed that 330 gratings with high and low refractive indexes can be written in 1 mm, and it is expected that high storage density will be achieved.

Embedded image Further, as a material capable of inducing refractive index dichroism to perform hologram recording, a polymer compound represented by the following general formula (α) [M. Sato, M. Hayakawa, K. Nakagawa, H.
Fujiwara, Macromol. Rapid Commun., 15, 21 (1994)]
It has been known.

Embedded image It is known that this polymer compound causes a liquid crystal-non-liquid crystal phase transition phenomenon to occur only in a very narrow region. For example, when two coherent laser beams are irradiated on a material made of this polymer compound to form an interference pattern in the material, the liquid crystal-non-liquid crystal is formed only in a region where the two laser beams strengthen each other. A refractive index modulation structure accompanying the transition is formed. In this modulation structure, the distance between the two refractive index maxima, that is, the period of the modulation structure should be compared with the wavelength region of the irradiation laser light, and it can be seen that this modulation structure is extremely fine. Further, this modulation structure is maintained even after the laser beam irradiation is stopped. This is because the rate of change between the liquid crystal structure and the non-liquid crystal structure thus formed is sufficiently low at room temperature. Unless the light is newly heated entirely or locally by laser light irradiation in a thermal mode, the modulation structure is not changed. Is not lost.

Materials capable of recording holograms as described above are required to satisfy at least the following requirements.

That is, the material used as a whole has liquid crystallinity in an appropriate temperature range, and has a molecular structure in which aromatic atomic groups are uniaxially arranged in the direction of the main chain. Refractive index dichroism is induced, and the main chain contains a flexible molecular chain, and the arrangement of the main chain molecule changes due to a change in the molecular structure of the photoisomerizable atomic group. A material known to date has an azobenzene structure as a light-sensitive atomic group, and the atomic group containing a cyano group in the azobenzene skeleton with good linearity functions as a mesogen during liquid crystal formation. Aromatic-
There are aliphatic polyesters.

[0013] The main measures of the performance of an optical recording medium include the storage capacity, the transfer speed of data to be read and written, and the stability of recording. Conventionally, as the characteristics of optical recording media, various studies have been made on increasing the storage capacity as described above, but there is little systematic knowledge on the recording speed of these organic material-based optical recording materials. You can say.

Considering that the recording mechanism of the photoresponsive resin is related to the motion of the polymer, since these polymers take a liquid crystal state, the recording speed is determined by the phase transition point of the polymer (liquid crystal). -Amorphous transition point, glass transition point, melting point, etc.). Therefore, if simply considered, it seems that a molecular design that increases the mobility of the molecule, that is, lowers the thermal phase transition temperature, is effective for improving the recording speed. However, it must be sufficiently considered that a decrease in the phase transition temperature of the polymer leads to instability of the recording state, which may significantly impair the storage stability of the optical recording medium.

As described above, generally, recording stability and response speed have opposite characteristics, and it has been difficult to improve the recording speed while maintaining the recording capacity and the recording stability.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and a first object of the present invention is to provide a novel compound useful as an optical recording material. The second object of the present invention is that the optical recording speed is high, and
An object of the present invention is to provide an optical recording medium which is excellent in memory system, modulation degree, multiplicity and record retention without impairing optical recording characteristics. A third object of the present invention is to provide an optical recording medium suitable for hologram recording, especially for polarization hologram recording.

[0017]

Means for Solving the Problems The present inventors have searched for a material having a liquid crystal phase transition point and a glass transition point on a low temperature side without impairing various conditions required for an optical recording medium, and have achieved the present invention. Done More specifically, for a polymer having a chemical structure represented by the general formula (α), which is an atomic group that is photoisomerizable and can function as a mesogen, without changing the side chain cyano-substituted azobenzene structure. By changing the main chain structure, which is considered to have a greater effect on the thermal properties of polymers, we conducted research on the idea that a more suitable material as a hologram storage material could be obtained. It has been found that the use of an alkyl chain having 8 or 10 carbon atoms in the main chain provides a particularly excellent material as a hologram storage medium, thereby completing the present invention.

That is, the photoreactive polyester of the present invention is characterized by having a structure represented by the following general formula (1).

Embedded image In the formula, m represents an integer of 2 to 18, and 1 represents an integer of 8 or 10. W represents an ether bond, a thioether bond, a substituted imino bond, a ketone bond, a sulfone bond or a sulfoxide bond.

N represents an integer of 5 to 500.

The photoreactive polyester represented by the general formula (1) can be obtained by appropriately combining a photoresponsive dicarboxylic acid monomer represented by the following general formula (2) and a diol compound represented by the general formula (3). It can be produced by reacting in the presence of a catalyst.

Embedded image In the general formula (2), X represents a lower alkyloxy group, a substituted or unsubstituted benzyloxy group, a substituted or unsubstituted phenyloxy group, an acid residue of a lower fatty acid, or an acid residue of a substituted or unsubstituted benzoic acid. , A halogen atom, and m is from 2
Indicates an integer of 18.

Embedded image In the general formula (3), 1 represents an integer of 8 or 10. W represents an ether bond, a thioether bond, a substituted imino bond, a ketone bond, a sulfone bond or a sulfoxide bond.

An optical recording medium according to a third aspect of the present invention is an optical recording medium which performs recording by utilizing a change in absorption or a change in refractive index of the optical recording material caused by irradiating light or applying heat to the optical recording material. A medium, wherein a photoreactive polyester represented by the general formula (1) is used as the optical recording material.

The recording is a hologram recording, and the hologram recording is a hologram recording capable of independently recording when the polarization directions of the incident object light and the reference light are horizontal polarization and vertical polarization. Is a preferred embodiment.

In the polyester represented by the above general formula (1), which is a novel compound of the present invention, the cyanoazobenzene structure present in the side chain serves as a mesogen in the formation of liquid crystals, and the oxyhesamethylene structure leading to this serves as a tail. ). On the other hand, since the main chain structure of this polymer contains a flexible aliphatic carbon chain, it does not hinder liquid crystal formation due to association of side chains, and the polymer as a whole exhibits liquid crystallinity. Furthermore, a partial change in the orientation of the main chain itself is induced with the formation of the liquid crystal in the side chain, and
Since the main chain contains a large amount of p-phenylene structure that raises the refractive index, a large dichroic refractive index is induced in the alignment direction of the liquid crystal and in the direction perpendicular thereto.

On the other hand, the azo group of this polymer causes cis-trans photoisomerization by light absorption. Cisated azobenzene no longer functions as a mesogen because of its bent structure. Therefore, this polymer functions as a photosensitive polymer whose liquid crystallinity is lost by light irradiation. At this time, various properties due to the liquid crystallinity of the polymer, for example, dichroism of the refractive index in the main axis direction of the liquid crystal and in the direction perpendicular thereto are also lost.

From the above properties, the polyester represented by the general formula (1), which is a novel compound of the present invention, has suitability as an optical storage medium.

Further, the polyester represented by the general formula (1), which is a novel compound of the present invention, has a glass transition temperature of about 20 ° C. compared to a similar polyester having a known glass transition temperature, for example, a polyester represented by the general formula (α). Low, the temperature at which the liquid crystal is displayed is low. This is presumably because the main chain alkyl chain in the repeating structure is long and flexible.

This indicates that the mobility of the polymer is higher than that of a known similar polyester. As a result, in the polyester represented by the general formula (1), which is a novel compound of the present invention, it is possible to operate at a higher speed in the process of optical writing and erasing.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied various polyester-based liquid crystal polymers containing a cyanoazobenzene derivative which is known to have photoreactivity in the side chain. The photoresponsive polyester shown in 1) has the same optical memory properties as existing liquid crystal polymers, and has a lower phase transition point than conventional ones, and enables faster optical writing. And completed the present invention.

First, a photoresponsive polyester represented by the following general formula (1), which is a novel compound that can be used as an optical recording material of the optical recording medium of the present invention, will be described.

Embedded image In the general formula (1), m is an integer of 2 to 18,
It preferably represents an integer of 4 to 12.

1 represents an integer of 8 or 10. In the present invention, this numerical value is characteristic, and as described above, this specific chain length is considered to contribute to the response speed.

W represents an ether bond, a thioether bond, a substituted imino bond, a ketone bond, a sulfone bond or a sulfoxide bond. Among them, an ether bond or a ketone bond is preferable.

Further, n represents an integer of 5 to 500, more preferably an integer of 10 to 100.

Next, a method for producing the photoresponsive polyester represented by the general formula (1) will be specifically described.

The polyester can be synthesized as shown in the following chemical reaction formula.

Embedded image

Embedded image First, p-cyanoaniline represented by the above chemical formula (Chemical formula 12) is diazotized by the action of nitrite and an acid (Chemical formula 13), and this is coupled with phenol represented by the above chemical formula (Chemical formula 14) to give 4′-. Synthesize hydroxy-4 ''-cyanoazobenzene (Formula 15). This was reacted with 1,6-dibromohexane represented by the above formula (formula 16) under the reaction conditions for the synthesis of Williamson's ether to give 4 ′-(6-bromohexyl) oxy- represented by the above formula (formula 17). Synthesize 4 ''-cyanoazobenzene. This is reacted with diethyl ester of 3-hydroxyisophthalic acid (Chemical formula 18) also under the reaction conditions of Williamson's ether synthesis to synthesize an azobenzene-bonded isophthalic acid derivative represented by the above chemical formula (Chemical formula 19). The reaction conditions for Williamson's ether synthesis include reaction conditions in a protic polar solvent (methanol, ethanol, etc.), reaction conditions in an aprotic polar solvent (dimethylformamide, dimethylsulfoxide, etc.), phase transfer reaction Reaction conditions using the above can be selected.

The azobenzene-bonded isophthalic acid derivative thus synthesized can be condensed with various aliphatic diols, diols containing an aromatic ring, and bisphenol under appropriate conditions in the same manner as ordinary diesters of aromatic dicarboxylic acids. By doing so, it is possible to lead to an azobenzene-bonded polyester. For example, (Formula 2
By reacting with a diol derived from the bisphenol compound represented by 1) by a high-temperature polycondensation method by transesterification, a polyester represented by the following general formula (1) can be obtained. Here, the polyester represented by the general formula (1) is described separately for a case where l is 8 and a case where l is 10.

Embedded image (In the formula, W represents an ether bond, a thioether bond, a substituted imino bond, a ketone bond, a sulfone bond or a sulfoxide bond.)

Here, as the reaction conditions, standard reaction conditions described in the literature can be selected. [Polymer Synthesis, edited by The Chemical Society of Japan (Experimental Chemistry Lecture 28, Maruzen (1992)) p22
0, Otsu / Kinoshita "Experimental method for polymer synthesis" (Chemical Doujin (197
2)) p320]. At this time, as a catalyst used for performing the reaction, a better result can be obtained by using a known reaction catalyst such as calcium acetate, zinc acetate, and antimony oxide which is effective in a high-temperature polycondensation method by transesterification.

In the following, specific examples of the photoresponsive polyester represented by the general formula (1) include the exemplary compounds (1) to (14), but the present invention is not limited to these specific examples.

Embedded image

Embedded image

Embedded image

Embedded image Next, the optical recording medium of the present invention will be described.

The optical recording medium of the present invention is an optical recording medium capable of optical recording utilizing an absorption change or a refractive index change caused by irradiating light or applying heat to the optical recording material. Wherein the photoresponsive polyester represented by the general formula (1) is used.

The optical recording medium of the present invention may have a laminated structure in which a photosensitive layer made of the optical recording material is formed on a substrate, and the entire optical recording medium is formed of the optical recording material. It may be an integral type.

As a substrate which can be used for an optical recording medium in which a photosensitive layer is formed on a substrate, a substrate which is transparent and robust in a wavelength range to be used and which does not cause remarkable deterioration and dimensional change in a normal temperature and humidity range is widely used. be able to. Specifically, soda glass, borosilicate glass, potash glass, acrylic plate,
Examples include a polyester (PET) sheet.

In the optical recording medium of the present invention, the thickness of the photosensitive layer is preferably about 1 μm to 5 mm, preferably 50 to 300 μm, in order to realize good optical recording. If the thickness of the photosensitive layer is less than 1 μm, the optical path is too short, the induced birefringence is not enough to perform data recording, and if it exceeds 5 mm, the loss due to light absorption is large, making it unsuitable as a recording medium. Neither is preferred.

From a practical point of view, in addition to the thickness of the photosensitive layer, the optical recording material may be used to obtain optical properties such as light transmittance, flatness and refractive index, and physical properties such as strength and dimensional stability. It is preferred that the values be in the preferred ranges.

As described above, the optical recording medium of the present invention is used for optical recording utilizing a change in absorption or a change in refractive index which occurs in an optical recording material upon irradiation with light or application of heat.

Examples of the optical recording include hologram recording, optical absorptivity modulation recording, and optical reflectance modulation recording. Among them, the optical recording suitable for the optical recording medium of the present invention is hologram recording.

In hologram recording, hologram recording in which a plurality of holograms can be recorded at a single location by changing the angle between the normal to the recording surface and the incident object light, and changing the position of the incident light on the recording surface A hologram recording in which a plurality of holograms can be recorded in an overlapping area by causing the hologram recording to be performed can be given, but a hologram recording suitable for the optical recording medium of the present invention is performed by changing a position of incident light with respect to a recording surface. This is a hologram recording in which a plurality of holograms can be recorded. Further, according to the material of the present invention, it is possible to record a hologram independently when the polarization directions of the incident object light and the reference light are horizontal polarization and vertical polarization.

Hereinafter, the principle of hologram recording will be briefly described together with the apparatus used for the hologram recording.

FIG. 2 is a schematic diagram showing an optical system of a digital hologram memory to which the optical recording medium of the present invention can be applied. This figure shows an optical system of a digital hologram memory described in Science Vol. 265 p (749) (1994).
In this example, lithium niobate (LiNO ₃ ) is used as a recording medium.
15 is used. Light emitted from the light source 6 is split by the beam splitter 12 into two light waves. The light transmitted through the beam splitter 12 becomes parallel light having a large diameter by the lens 10 and enters the spatial modulator 4. The spatial modulator 4 is controlled by a computer 11 and generates a signal light 1 having a two-dimensional intensity distribution. The signal light 1 is Fourier-transformed by the lens 7 and is incident on lithium niobate (LiNO ₃ ) 15. This is the reference light 2. As described above, the hologram recording is performed by simultaneously inputting the signal light 1 and the reference light 2 to the lithium niobate (LiNO ₃ ) 15. To read the hologram, use only the reference beam 2 as lithium niobate (LiNO ₃ )
15, the reference light 2 is diffracted on the optical path of the signal light 1 as if the signal light 1 passed through lithium niobate (LiNO ₃ ) 15, and this was reflected on the camera 9 by the lens 8. Make an image.

In the hologram recording and digital hologram recording apparatuses described above, a spatial light modulator is used for data input, and a differential code method is used for displaying bit data. In the data notation by the differential code method as shown in FIG. 3, two pixels are used as a pair, for example, 0 represents dark and light and 1 represents light and dark. When such a differential code method is used, the number of light and dark is always constant, so that the amount of object light passing through the spatial modulator is also constant. Therefore, it is not necessary to adjust the intensity of the reference light for each page. Further, in the reproduction of the hologram, unevenness in the amount of light is likely to occur, and it is difficult to make a uniform division between the black and white levels.

In the differential coding method, since one-bit data is displayed using at least two pixels, the pixel utilization efficiency is as low as 0.5. Therefore, there is a problem that the data density that can be recorded on one page is reduced. Furthermore, when the differential code method is used, a hologram reproduced image is captured by a two-dimensional optical element such as a CCD, converted into a serial electric signal, and then the edges are read electrically and converted into bit data. There is also a problem that the transfer speed is reduced. That is, even if a plurality of bit information can be read in parallel from the hologram, a high transmission speed cannot be achieved as a result by performing the electrical data processing serially.

Therefore, the present inventors use a material capable of recording independently with S and P polarized light, thereby controlling the polarization direction of the signal light applied to the material to perform recording on one optical recording medium. We proposed this and named it a polarization hologram recording method.
According to this method, digital hologram recording can be performed at a high S / N ratio without using the above-described differential coding method, and the substantial recording density can be improved about twice as compared with the conventional method. .

An important indicator of the performance of these materials is the speed of reading and writing. That is, no matter how large a recording capacity is achieved, it is not practical as a storage medium if reading and writing data takes unrealistic time.

Regarding the data reading speed, not only the polarization hologram recording method but also a recording method using a hologram is excellent in principle. Because the normal recording method treats the data as a one-dimensional point sequence, its reading is sequential (serial),
Hologram recording uses data as a two-dimensional matrix
This is because they can be handled in parallel at a time. It is also advantageous for high-speed data reading that data reading is a non-contact and non-delaying process of light refraction by a substance.

On the other hand, the hologram recording method has an advantage that data processing is performed in parallel for data writing, but the recording mechanism is based on a physical change of the medium such as writing of a refractive index grating in the medium. As a result, the rate depends on the material constant of the substance used.

Although the details of the mechanism of writing the refractive index grating in the polymer medium have not been fully elucidated until now, the phase structure such as the glassy state, crystal state, and liquid crystal state of the polymer has been described. Plays an important role, and it is presumed that the thermal properties of the polymer play an important role.

Therefore, the present inventors have studied using the glass transition point, which indicates the thermal properties of a polymer, as the first index. A material system which is about 20 degrees lower than that of the above material.

That is, when the recording characteristics when the photoresponsive polyester of the present invention was used as an optical recording material were evaluated, it took only about 120 milliseconds to write one frame (about 1 megabit) of data. It turned out to be. The present inventors have previously found a photoresponsive polymer having an excellent optical recording capacity and proposed it as Japanese Patent Application No. 10-284629. Considering that it took about 300 milliseconds to write data of a frame (about 1 megabit), the new resin of the present invention achieved a speedup of about 2.5 times.

The optical recording medium of the present invention has a two-dimensional shape such as a sheet shape, a tape shape, a film shape, a disc shape or the like.
Regardless of the shape of the dimensional shape, the characteristics can be suitably exhibited. As a specific method of forming the optical recording medium, a suitable solvent for the optical recording material, for example, chloroform, methylene chloride, o-dichlorobenzene, tetrahydrofuran, anisole, an aliphatic or aromatic halogenated solvent such as acetophenone, It is dissolved in an ether-based solvent, and the solution is molded into a transparent and tough film-like shape on a substrate such as glass, or the powder, pellet or flake-like solid of an optical recording material is heated and compressed by a hot press method. Then, a method of forming a transparent and tough film-like shape on a substrate such as glass can be given. These films may be used in a state of being laminated on a substrate, or may be used after being formed into a film shape and peeled from the substrate (free-standing state).

Preferred embodiments of the optical recording medium of the present invention include the following optical recording media (1) to (5).

(1) An optical recording medium having a disk shape and capable of rotating and scanning a write / read head over a moving radius to perform recording / reproduction.

(2) An optical recording medium having a sheet-like shape, on which a read / write head can two-dimensionally scan to perform recording and reproduction.

(3) An optical recording medium having a tape-like shape and capable of recording and reproducing by scanning a predetermined portion with a read / write head while winding the tape.

(4) A frame (stage) having a three-dimensional bulk shape, which can be fixed or movable.
An optical recording medium fixed on the optical recording medium and capable of performing recording and reproduction by scanning the surface or inside thereof with a movable or fixed read / write head.

(5) A film-like material is appropriately laminated to have a two-dimensional shape such as a disk shape, a sheet shape, a card shape, a drum shape, or another three-dimensional shape. An optical recording medium capable of performing recording and reproduction by scanning with a read / write head by the method described in (1) to (4) or a method combining these methods.

As the optical recording apparatus using the optical recording medium of the present invention, a known apparatus can be used.
For example, there is an optical system shown in FIG. Instead of the lithium niobate (LiNO ₃ ) 15 in the optical system shown in FIG. 2, an optical recording medium of the present invention which is appropriately shaped is provided, and hologram recording / reproduction can be performed.

[0065]

EXAMPLES The present invention will be specifically described below with reference to examples, but is not limited to the examples unless it exceeds the gist of the present invention.

(1) Synthesis of diethyl 5-hydroxyisophthalate 5-hydroxyisophthalic acid 18 was placed in a two-liter three-necked flask.
2 g (1 mol), 1500 ml of ethanol and 10 ml of concentrated sulfuric acid are taken and reacted by heating under reflux for 24 hours. After completion of the reaction, the system is concentrated to about 1/2 by a rotary evaporator. When the obtained colorless viscous solution is poured into a cold sodium hydrogencarbonate solution of about 20%, the droplets first float in the solution, but immediately solidify to obtain a white bulky crude product. This is filtered off and dried under reduced pressure. Yield 229g (96
%). This was recrystallized from ethanol to obtain 190 g of diethyl 5-hydroxyisophthalate. 80% yield.

(2) Synthesis of 4′-hydroxy-4 ″ -cyano-azobenzene) In a 3 liter beaker, 750 ml of 6N hydrochloric acid was added, and 118 g (1 mol) of finely crushed 4-cyanoaniline was added thereto, followed by stirring. Then, add about 300 g of ice and cool the system. On the other hand, 80 g (1.16 mol) of sodium nitrite is dissolved in 500 ml of water. 400m of sodium nitrite solution in suspension
is added over about 20 minutes, and after completion of the dropwise addition, the solution is stirred at about 5 ° C. for 1 hour. 94 g (1 mol) of phenol is added to this solution.
The solution dissolved in 1 liter of 2N potassium hydroxide solution is gradually added, and the mixture is allowed to react overnight after mixing. After the completion of the reaction, the formed precipitate is separated by filtration and dried under reduced pressure to obtain 214 g (96%) of crude 4′-hydroxy-4 ″ -methyl-azobenzene. This was used for the next reaction without purification.

(3) 4 '-(6-bromohexyl) oxy-4''-
Synthesis of cyano-azobenzene In a 2 l three-necked flask equipped with a mechanical stirrer,
45 g (0.2 mol) of 4'-hydroxy-4 ''-methyl-azobenzene synthesized as described above, 448 g of 1,6-dibromohexane (2 mol
l), take anhydrous potassium carbonate 212 g (1.5 mol), acetone 80
Add 0 ml and stir to suspend. The reaction system is heated until acetone is refluxed to react hydroxyazobenzene with bromoalkane. After reacting for 20 hours, insoluble salts are removed by filtration, and the system is concentrated to about 1/3 with a rotary evaporator. 4 '-(6-bromohexyl) oxy-4''-produced by cooling this system in a refrigerator
Cyano-azobenzene crystallizes out. After filtering the product, a small amount of cold acetone, cold ether, washed sequentially with n-hexane and then dried under reduced pressure to give crude 4 '-(6-bromohexyl)
38.1 g of oxy-4 ″ -methyl-azobenzene are obtained. Yield 39g
(50.5% yield). This was recrystallized from ethanol to give 4 '-(6-
(Bromohexyl) oxy-4 ''-cyano-azobenzene 34 g
(44% yield). Melting point ° C. According to the analysis by high performance liquid chromatography, the purity was 98.6% or more.

(4) Synthesis of diethyl 5- [6- [4 ′-(4 ″ -cyano-phenylazo) phenoxy] hexyloxy] -isophthalate Diethyl 5-hydroxyisophthalate was placed in a 1-liter three-necked flask. Take 16.6 g (0.07 mol), 27.0 g (0.07 mol) of 4 '-(6-bromohexyl) oxy-4''-cyano-azobenzene, 15.1 g (0.11 mol) of anhydrous potassium carbonate, and place 300 ml of acetone here.
Add. The system is heated at reflux for 24 hours to allow both to react. After completion of the reaction, the system was poured into cold water (1500 ml), and the resulting 5- [6
The diethyl [-[4 ′-(4 ″ -cyano-phenylazo) phenoxy] hexyloxy] -isophthalate is filtered off and dried under reduced pressure.
Yield 35.1 g (83%). This was recrystallized twice from acetone to give 28.9 g of the target substance, diethyl 5- [6- [4 '-(4''-cyano-phenylazo) phenoxy] hexyloxy] -isophthalate (75.
Obtain 9). Melting point ° C. According to the analysis by high performance liquid chromatography, the purity was 98.3% or more.

(5) Synthesis of 4,4'-bis- [8-hydroxyoctyloxy] -diphenyl ether In a 300 ml eggplant flask, 20.2 g (0.1 mol) of 4,4'-dihydroxy-diphenyl ether, 8-bromo-1- Hexanol 46g
(0.22 mol) and 41.4 g (0.3 mol) of potassium carbonate were added, and 100 ml of N, N-dimethylformamide was added thereto, and the mixture was stirred and suspended. The system is heated to 150 ° C in an oil bath and reacted for 24 hours. After completion of the reaction, the system was poured into 1 liter of water containing a small amount of hydrochloric acid, and the generated white powdery substance was filtered off and dried to obtain a crude 4,4 ′.
38 g of -bis- [6-hydroxyoctyloxy] -diphenyl ether are obtained. 83% yield. This was recrystallized from water-N, N-dimethylformamide to give 29 g of purified 4,4′-bis- [6-hydroxyoctyloxy] -diphenyl ether.

(6) Synthesis of 4,4'-bis- [8-hydroxyoctyloxy] -diphenyl ketone 21.4 g (0.1 mol) of 4,4'-dihydroxy-diphenyl ketone, 8-bromo- 46 g of 1-hexanol (0.
22 mol) and 41.4 g (0.3 mol) of potassium carbonate, 100 ml of N, N-dimethylformamide is added, and the mixture is stirred and suspended.
The system is heated to 150 ° C in an oil bath and reacted for 24 hours. After completion of the reaction, the system was poured into 1 liter of water containing a small amount of hydrochloric acid,
The resulting white powder is filtered off and dried to give crude 4,4'-bis- [8-hydroxyoctyloxy] -diphenyl ether
Get 43g. 90.3% yield. This was recrystallized from water-N, N-dimethylformamide to obtain 34 g of purified 4,4′-bis- [8-hydroxyoctyloxy] -diphenyl ketone. (7) Synthesis of 4,4'-bis- [10-hydroxydecyloxy] -diphenyl ether

In a 300 ml eggplant flask, 4,4'-dihydroxy
-Take 10.1 g (0.05 mol) of diphenyl ether, 23 g (0.11 mol) of 10-chloro-1-decanol and 20.7 g (0.15 mol) of potassium carbonate, add 70 ml of N, N-dimethylformamide, stir and suspend. The system is heated to 150 ° C in an oil bath and reacted for 24 hours. After completion of the reaction, the system was diluted with 1 l of water containing a small amount of hydrochloric acid
The resulting white powdery substance was filtered off and dried to obtain 19 g of crude 4,4′-bis- [10-hydroxydecyloxy] -diphenyl ether. 75% yield. This was recrystallized from water-N, N-dimethylformamide and purified to give 4,4'-bis- [10-
15.5 g of [hydroxydecyloxy] -diphenyl ether are obtained. (8) Synthesis of 4,4'-bis- [10-chlorodecyloxy] -diphenyl ketone

In a 300 ml eggplant flask, 4,4'-dihydroxy
-Take 10.7 g (0.05 mol) of diphenyl ether, 23 g (0.11 mol) of 10-chloro-1-decanol and 20.7 g (0.15 mol) of potassium carbonate, add 70 ml of N, N-dimethylformamide, stir and suspend. The system is heated to 150 ° C in an oil bath and reacted for 24 hours. After completion of the reaction, the system was diluted with 1 l of water containing a small amount of hydrochloric acid.
The resulting white powdery substance was filtered off and dried to obtain 22 g of crude 4,4′-bis- [10-hydroxydecyloxy] -diphenyl ether. Yield 83.5%. This was recrystallized from water-N, N-dimethylformamide to give 4,4′-bis- [6
[Chlorohexyloxy] -diphenyl ether 17 g is obtained.

Example 1 (Diethyl 5- [6- [4 '-(4 ″ -cyano-phenylazo) phenoxy] hexyloxy] -isophthalate and 4,4'-bis- [8-
Synthesis of polyester from hydroxyoctyloxy] -diphenyl ether) 5.43 g (0.1 mol) of diethyl 5- [6- [4 ′-(4 ″ -cyano-phenylazo) phenoxy] hexyloxy] -isophthalate,
4.59 g (0.1 mol) of 4'-bis- [8-hydroxyoctyloxy] -diphenyl ether and 0.1 g of anhydrous zinc acetate were placed in a 100 ml three-necked flask equipped with a vacuum depressurizing device and a stirring device, and stirred under a nitrogen atmosphere. While heating, at 140 ° C for 2 hours,
The reaction is performed under a reduced pressure of about 10 Torr for 20 minutes. The system is then slowly depressurized to 2 Torr over 30 minutes. Finally, the temperature of the reaction system is raised to 180 ° C. while maintaining the degree of vacuum, and the reaction is performed for 4 hours. After completion of the reaction, the system is dissolved in chloroform and poured into hot water to take out a crude polymer. This is dissolved in chloroform,
It is poured into methanol to reprecipitate and take out the target polymer. The yield was 6.21 g (64.3% yield). The obtained polymer is a polyester having the above-mentioned exemplary compound (1) and m = 6.

Example 2 (5- [6- [4 ′-(4 ″ -cyano-phenylazo) phenoxy] hexyloxy] -isophthalic acid diethyl ester and 4,4′-bis- [8-
Synthesis of Polyester from [Hydroxyoctyloxy] -diphenylketone)

As a monomer, 4,4′-bis- [8-hydroxyoctyloxy] -diphenyl ether is used instead of 4,4′-
A desired polyester is obtained in the same manner as in Example 1 except that a considerable amount of bis- [8-hydroxyoctyloxy] -diphenyl ketone is used. Yield 6.51 g (67% yield). The obtained polymer is a polyester of the exemplified compound (3) with m = 6.

Example 3 Diethyl 5- [6- [4 '-(4 ″ -cyano-phenylazo) phenoxy] hexyloxy] -isophthalate and 4,4′-bis- [10-
Synthesis of polyester from hydroxydecyloxy] -diphenyl ether

As a monomer, instead of 4,4′-bis- [8-hydroxyoctyloxy] -diphenyl ether, 4,4′-
The desired polyester is obtained in the same manner as in Example 1 except that a considerable amount of bis- [10-hydroxyoctyloxy] -diphenyl ether is used. Yield 7.11 g (69.5% yield).
The obtained polymer is the polyester of the exemplified compound (2) with m = 6.

Example 4 Diethyl (5- [6- [4 '-(4 ″ -cyano-phenylazo) phenoxy] hexyloxy] -isophthalate and 4,4′-bis- [10-
Synthesis of Polyester from [Hydroxydecyloxy] -diphenylketone)

As a monomer, instead of 4,4'-bis- [8-hydroxyoctyloxy] -diphenyl ether, 4,4'-
The desired polyester is obtained in the same manner as in Example 1 except that a considerable amount of bis- [10-hydroxydecyloxy] -diphenyl ketone is used. Yield 6.99 g (67.6% yield). The obtained polymer is a polyester of the exemplified compound (4) with m = 6. [Example 5]

(Evaluation of Response Speed as Optical Storage Medium) The photoreactive polyester resin obtained in Example 2 and the photoreactive polyester resin represented by the above-mentioned known general formula (α) were subjected to light The irradiation time and the degree of birefringence induced by the light irradiation were measured. Here, a sample having a film thickness of 12 μm was used. The light intensity used was 8 W / cm ² . The results are shown in the graph of FIG.

As is clear from the graph of FIG. 4, when the photoreactive polyester of the present invention was used, the birefringence formation speed was high especially in the low irradiation region, and it was difficult to obtain the same photoinduced birefringence. It was found that the light irradiation time was as short as about 18% and the light response speed was excellent.

[0083]

The novel photoresponsive polyester of the present invention is suitable as a polymer recording medium for holograms having high-speed recording characteristics while maintaining excellent polarization recording characteristics. In addition, the optical storage medium of the present invention using this novel compound has excellent effects such as excellent recording capacity and a high recording speed.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a photorefractive effect, that is, a mechanism of a refractive index change induced by light irradiation.

FIG. 2 is a schematic diagram showing an optical system of a digital hologram memory applicable to the optical recording medium of the present invention.

FIG. 3 is a diagram showing a concept of recording by a differential code method.

FIG. 4 is a graph showing the relationship between the light irradiation time and the degree of birefringence induced by the light irradiation in the photoreactive polyester resin.

[Explanation of symbols]

 Reference Signs List 1 signal light 2 reference light 3 diffracted light 4 spatial light modulator 5 optical recording medium 6 light source 7 Fourier transform lens 8 Fourier transform lens 9 two-dimensional light receiving element 10 collimating lens 11 computer 12 beam splitter 13 mirror 14 mirror

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsunori Kono 430 Nakaicho Sakai, Ashigara-gun, Kanagawa Prefecture Inside Green X-Tech Fuji Xerox Co., Ltd. F term (reference) 2H111 EA04 EA12 EA25 EA32 EA33 EA37 EA39 EA43 FB42 FB50 2H123 AA00 AA51 2K008 AA04 DD12 FF07 FF17 4J029 AA03 AB04 AC01 AE04 BB08A BH01 BH02 BH07 5C09A CH01A

Claims (5)

[Claims] 1. A photoreactive polyester having a structure represented by the following general formula (1). Embedded image In the formula, m represents an integer of 2 to 18, and 1 represents an integer of 8 or 10. W represents an ether bond, a thioether bond, a substituted imino bond, a ketone bond, a sulfone bond or a sulfoxide bond. n represents an integer of 5 to 500. 2. A photoresponsive dicarboxylic acid monomer represented by the following general formula (2) is reacted with a diol compound represented by the following general formula (3) in the presence of a suitable catalyst to obtain the compound represented by the above general formula (1).
A method for producing a photoreactive polyester which obtains a polyester represented by the formula: Embedded image In the general formula (2), X represents a lower alkyloxy group, a substituted or unsubstituted benzyloxy group, a substituted or unsubstituted phenyloxy group, an acid residue of a lower fatty acid, or an acid residue of a substituted or unsubstituted benzoic acid. , A halogen atom, and m is from 2
Indicates an integer of 18. Embedded image In the general formula (3), 1 represents an integer of 8 or 10. W represents an ether bond, a thioether bond, a substituted imino bond, a ketone bond, a sulfone bond or a sulfoxide bond. 3. An optical recording medium for performing recording by utilizing an absorption change or a refractive index change of the optical recording material caused by irradiating light or applying heat to the optical recording material, wherein the optical recording material has the general formula An optical recording medium using the photoreactive polyester represented by (1). 4. The optical recording medium according to claim 3, wherein the recording is a hologram recording. 5. The optical recording medium according to claim 4, wherein the hologram recording is a hologram recording capable of recording independently when the polarization directions of the incident object light and the reference light are horizontal polarization and vertical polarization.