JPS6137489A - Optical recording element - Google Patents

Abstract

PURPOSE:To obtain an optical recording element capable of performing high density recording with high reliability, by providing an A-layer comprising a leuco dye, a B-layer comprising a phenolic compound forming a color upon the contact with the leuco dye and the light absorbing layer interposed between the layers A, B and forming the B-layer from a monomolecular or built-up film layer. CONSTITUTION:An A-layer 2 comprising a leuco dye, a B-layer 4 comprising a phenolic compound and the light absorbing layer 3 comprising a light absorbing substance interposed between both layers 2, 4 to form a laminate wherein the B-layer 4 comprises a monomolecular or built-up film and each of the A-layer 2 and the light absorbing layer 3 comprises an accumulation film and the B- layer 4 is supported by a substrate 1 while substrate/B-layer/light absorbing layer/A-layer are laminated in this order. By this optical recording element, higher density recording is enabled as compared with a conventional optical recording element. A signal/noise ratio is high and the reliability of recording can be enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical recording element using an organic material, and in particular to a usable optical recording device with high reliability and high density recording using a highly molecularly oriented organic thin film. This relates to recording elements.

[Background Art] Recently, optical disks have been attracting attention as a central player in office automation (OA).

The reason for this is that a single optical disc can record (or store) a large amount of documents, literature, etc. Therefore, introducing an information storage device using this optical disc will revolutionize the organization and management of documents and literature in offices. It is something that brings. In addition, the recording element for the optical disk is inexpensive;
2. Description of the Related Art Elements made of organic materials that have features such as ease of manufacture and high-density recording are attracting attention.

Among the conventional techniques using such organic recording materials, a two-component optical recording device that utilizes a coloring reaction caused by contact between a coloring agent and a preservative has been reported (Nikkei Sangyo Shimbun, 1972).
(October 18, 2016).

An example of the conventional optical recording element will be explained based on the drawings. As shown in FIG. It consists of a laminated structure.

The coloring agent (leuco body) and the stabilizing agent are colorless or light-colored when each exists alone.

When recording on the recording element, light absorption F! is performed as shown in FIG. 2(b). When a laser beam 8 is irradiated onto a desired position of the layer 6, the portion of the light absorption layer irradiated with the laser beam absorbs the laser beam, melts, and ruptures, creating a small hole.

As a result, as shown in FIG. 2(C), the coloring agent and the time-setting agent, which were separated by the light absorption M6, mix through this small hole and develop a color. Information is recorded or stored in the form of coloring points 9, and reading is performed by scanning the recording element with another light source and detecting changes in reflectance, transmittance, etc. due to the coloring points.

[Problems to be Solved by the Invention] In the above optical recording element, in order to achieve high recording density, it is desirable that the light absorption layer 6 be extremely thin, flat, and without uneven thickness. However, in conventional optical recording elements, the light absorption layer is coated on the substrate by, for example, a vacuum evaporation method or a spin coating method, so the thickness is reduced to 20%.
If an attempt was made to reduce the thickness to 0 to 500 A, many bottle balls would occur, and the two components, the coloring agent and the preservative, would come into contact with each other at the pinholes and develop color, resulting in a lack of reliability. Moreover, since the molecular distribution and orientation within the film of each layer formed by the above-mentioned conventional coating method is random, light scattering occurs within the film with light irradiation, and when viewed microscopically,
The degree of chemical reaction that occurs with each light irradiation differs.

Furthermore, the above-mentioned coating method has the disadvantage that when the substrate of the optical disk is made large in area, the S thickness becomes uneven and the recording quality becomes uneven.

Therefore, as an optical recording element, it is desirable that the molecular distribution and orientation within the film be uniform, that there are no pinholes, and that the film thickness is uniform, and that the film thickness be as thin as possible to achieve high recording density and high reliability. The present invention has been made in view of these demands, and an object of the present invention is to provide an optical recording element that can perform highly reliable and high-density recording. Another object of the present invention is to provide an optical recording element that is easy to manufacture and inexpensive.A further object of the present invention is to provide an optical recording element with a large area.

[Means for solving the problems] and [Action 1, that is, the present invention is directed to A, which is composed of a leuco form of a normally colorless or light-colored dye.
a layer B made of a phenolic compound that develops color when it comes into contact with the leuco form of the dye; and a light absorption layer interposed between the layer A and the layer B, and (a) the layer B is made of phenol. An optical recording element characterized in that it is composed of a monomolecular film of a chemical compound or a cumulative film thereof.

The present invention will be explained in detail below.

The optical recording element according to the present invention utilizes a two-component coloring reaction, and more specifically, it utilizes a coloring reaction between a leuco dye and a phenolic compound that develops a color when it comes into contact with the leuco dye. It is.

Therefore, the optical recording element according to the present invention has a layer A consisting of a leuco form of a normally colorless or light-colored dye, a layer B consisting of a phenolic compound that develops color when it comes into contact with the leuco form of the dye, and a layer A and a layer B. It basically consists of a light-absorbing layer that is interposed between the light-absorbing layer and the light-absorbing layer that absorbs light and heats up to 9i to melt or sublimate itself.

Examples of the leuco type of the usually colorless to light-colored dye of the A layer used in the present invention include triphenylmethane type, fluoran type, phenothiazine type, auramine type, spiropyran type, etc., and specific compounds contained in them include The details are listed in Table 1.

In the present invention, AF! - is formed by conventional coating method n! Any film may be used as J, and among these, a layer consisting of a deposited film such as a vapor deposited film, a coating film, a dipping film, a laminate, etc. is preferable.

Next, examples of the phenolic compounds in the B layer that develop color upon contact with the leuco form of the dye include pt-butylphenol, α-naphthol, β-naphthol, phenolphthalein, bisphenol A, and 4-hydroxydiphenoxide. , 4-hydroxyacetophenone, 3.
5-xylenol, thymol, hydroquinone, 4-tert-butylphenol, α-naphthol, 4-hydroxyphenoxide, β-naphthol, methyl-4-
Hydroxybenzoate, catechol, 4-hydroxyacetophenone, resorcinol, 4-tert-octylcatechol, 4,4'-secondary-butylidenediphenol, 2,2'-dihydroxydiphenyl, 2
．． 2'-methylenebis(4-methyl6-tert-butylphenol), 2,2'-bis(4'-oxyphenyl)propane, 4,4'-isopropylidenebis(2
-tertiary-butylphenol), 4,4'-secondary-butylidene diphenol, pyrogallol, phloroglucin, phloroglucin carboxylic acid, and the like.

In the present invention, since layer B is formed from a layer consisting of a single molecule n9 or its cumulative mn1N, the phenolic compound has a hydrophilic group at an appropriate site within the molecule.

It is necessary to use a derivative into which a hydrophobic group or both groups are introduced.

Any commonly used hydrophobic group and parent tree group can be used.

Particularly preferably, the hydrophobic group is a long-chain alkyl group having 5 to 30 carbon atoms, and the parent group is preferably a carboxyl group and its metal in (for example, cadmium salt).

Note that the thickness of the A layer and the B layer is preferably in the range of 200 Å to 101 L, and preferably in the range of 1,000 Å to Ig.

Next, as the light-absorbing substance used for forming the light-absorbing layer in the present invention, a meltable light-absorbing dye that absorbs infrared rays and melts, or a sublimable light-absorbing dye that absorbs infrared rays and sublimates is suitable. .

Examples of such light-absorbing dyes include copper phlocyanine,
Examples include metal phthalocyanines such as vanadium phthalocyanine, metal-containing azo dyes, acidic azo dyes, and xanthine dyes such as fluorescein.

The light-absorbing layer may be any film formed by conventional coating methods, including, for example, vapor-deposited films,
A layer consisting of a deposited film such as a coated film, a dipping film, or a laminate is preferred.

The thickness of the light absorption layer is desirably in the range of 1110A to 1,000A, preferably in the range of 140A to 400A.

In addition, the materials used for the substrate in the present invention include:
Semiconductor materials such as silicon, metal materials such as aluminum, preferably tempered glass, and acrylic (PMMA), Ho! ,
Preferred are plastic materials such as J Carpone (PC), polypropylene, polyvinyl chloride (PVC), and polystyrene, and ceramic materials.

One feature of the optical recording element according to the present invention is that the eight layers are composed of a monomolecular film of a phenolic compound or a cumulative film thereof.

As a method for producing a monomolecular film or a cumulative film thereof having such high orderliness and orientation of molecules, for example, 1. La
The Langmuir-Prodgett method (CLB method) developed by Ngmuir et al. The Langmuir-Prodgett method uses, for example, a molecule with a structure that has a parent wood group and a hydrophobic group in the molecule, and when the balance between the two (balance of amphiphilicity) is maintained moderately, one molecule will reach the parent tree on the water surface. This is a method of creating a monomolecular film or a monomolecular cumulative film by using the fact that the monomolecular layer is formed with the group facing downward. The monomolecular layer on the water surface has the characteristics of a two-dimensional system.0 When the molecules are sparsely dispersed, the equation for a two-dimensional ideal gas exists between the area per molecule A and the surface pressure ■.

nA=kT holds, resulting in a "° gas film", where k is Portzmann's constant and T is the absolute temperature. If A is made sufficiently small, the intermolecular interaction becomes strong and a two-dimensional solid becomes a condensed film (or solid film). The condensed film can be transferred layer by layer onto the surface of carriers having various materials and shapes, such as plastic substrates and glass substrates.

Next, the method for forming a monomolecular film or a cumulative film of an organic molecule having a parent group and a hydrophobic group, which is a phenolic compound used in the present invention, will be described in further detail.

First, the organic molecule is dissolved in a volatile solvent such as benzene, chloroform, etc., and spread on the aqueous phase 11 in the water tank 10 of the monomolecular cumulative film forming apparatus schematically shown in FIG. 3 using a cylinder or the like.

As the solvent evaporates, the organic molecules develop on the water phase 11 with the parent tree groups 12 facing the water phase and the hydrophobic groups 13 facing the gas phase.

Next, a partition plate (or float) 14 is installed to prevent this precipitate (organic molecules) from freely diffusing and spreading too much on the aqueous phase 11.
is provided to limit the developed area and control the state of aggregation of the membrane material, thereby obtaining a surface pressure n proportional to the state of aggregation. By moving this partition plate 14, it is possible to reduce the developed area, control the agglomeration state of the film material, gradually increase the surface pressure 1, and set the surface pressure 2 suitable for producing a cumulative film. By gently vertically moving the clean substrate 14 up and down while maintaining this surface pressure, monomolecular B5Ite is transferred onto the substrate.

The monomolecular film 16 is manufactured in the above manner, but the monomolecular layer cumulative
! In step 117, a desired cumulative number of monomolecular layers is formed by repeating the above operations.

For example, when the substrate 15 whose surface is hydrophilic is pulled out of water in a direction across the water surface, the hydrophilic groups of the organic molecules are removed from the substrate 15.
A side facing monolayer 1B is formed on the substrate 15. When the substrate 15 is moved up and down as described above, the monomolecular layer 16 is stacked one by one in each process.The direction of the film-forming molecules is reversed in the pulling process and the dipping process, so this method In this case, a so-called Y-type film is formed in which the parent wood groups of the organic molecules and the parent wood groups, and the hydrophobic groups of the organic molecules face each other (Fig. 4(a)).

The Y-type film is strong because the hydrophilic groups and hydrophobic groups of the organic molecules face each other.

In contrast, only when lowering the substrate 15 into the water,
There is also a method of transferring the organic molecules onto the substrate surface.

In this method, there is no change in the direction of the film-forming molecules even if they are accumulated, and an X-shaped film is formed in which the hydrophobic groups face the substrate 15 in all layers (Fig. 4(b)). The cumulative film in which the parent wood base faces the substrate 15 in all cases is called an X-type film (FIG. 4(c)).

The X-type film is obtained by transferring organic molecules to the substrate surface only when the core plate 15 is lifted out of the water.

The monomolecular film and monomolecular layer cumulative film formed on the substrate by the above method have high density and a high degree of order and orientation, and by configuring the recording layer with these films, photothermal A recording element having a high-density and high-resolution recording function can be obtained. Further, as can be seen from the principles thereof, these film forming methods are very simple methods, and a recording element having the above-mentioned excellent recording function can be provided at low cost.

The substrate on which the undeveloped monomolecular film or monomolecular cumulative film described above is formed is not particularly limited, but if a surfactant is attached to the surface of the substrate.

When the monomolecular layer is transferred from the water surface, the monomolecular film is disturbed and a good monomolecular film or monomolecular layer accumulation film cannot be formed, so it is necessary to use a substrate with a clean surface.

The monomolecular film or monomolecular layer accumulation film on the substrate is sufficiently strongly fixed and rarely peels or peels off from the substrate. An adhesive layer can also be provided between the layer stacks. Furthermore, the adhesion force can be strengthened by selecting the monomolecular layer formation conditions, such as the hydrogen ion concentration of the aqueous phase, the ion species, the water temperature, the rate of raising and lowering the carrier, or the surface pressure.

Next, the method for forming the deposited film of layer A or light absorption layer is to pulverize and mix a water mixture obtained by adding a binder and water to the leuco form of the dye or the light absorption substance using a ball mill or the like.
This is done by applying it onto a substrate or the like using a conventional method.

The binder used in the present invention includes gelatin,
Natural polymers such as starch - 1 cellulose nitrate, la fibril derivatives such as carboxymethyl cellulose, semi-synthetic polymers such as natural rubber plastics such as chlorinated rubber and cyclized rubber, polyisobutylene, polystyrene, and terpenes Resin, polyacrylic acid, polyacrylic ester, polymethacrylic ester, polyacrylonitrile, polyacrylamide, polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacetal resin, polyvinyl chloride, polyvinylpyridine, polyvinylcarbazole, polybutadiene, polystyrene - Polymerizable synthetic polymers such as butadiene, butyl rubber, polyoxymethylene, polyethyleneimine, polyethyleneimine hydrochloride, poly(2-acryloxyethyldimethylsulfonium chloride), phenolic resins, amino resins, toluene resins, alkyd resins, Examples include condensation polymerization type synthetic polymers such as saturated polyester resin, allyl resin, polycarbonate, polyamide resin, polyether resin, silicone resin, furan resin, thiocol rubber, etc., and addition polymerization type resins such as polyurethane, polyurea, epoxy resin, etc. .

An example of the structure of an optical recording element according to the present invention manually manufactured by the method explained above is shown in FIG. 1, as shown in FIG. A laminate consisting of a light absorbing layer 3 made of a light absorbing substance interposed between the A layer and Be, the third layer 4 being a monomolecular film or a cumulative film thereof, and the A layer 2 and the light absorbing layer 3 being a deposited film. Three layers 4 are supported on a substrate l, and are laminated in the order of substrate/B layer/light absorption layer/A layer.

Furthermore, as another example, the AFJ of the laminate is supported on a substrate, and the substrate/Am/light absorption F! )/B layer may be laminated in this order, or two of the above laminates may be stacked and the lowest layer A or B layer may be supported on the substrate.

Since the optical recording element according to the present invention is constructed by separating the A layer and the B layer by a light absorption layer, by melting or sublimating the light absorption layer by infrared irradiation and making holes at desired positions, The color-forming compound in layer A and the time-setting compound in layer B come into contact and a color-forming reaction progresses, and a color-forming point is engraved at the corresponding position, allowing information to be recorded.

Therefore, the optical recording element according to the present invention can be mainly used as an optical disc. FIG. 5 shows an example of an information storage device having an optical pickup optical system for writing or reading information from the optical disc.

The information storage device is composed of a writing means consisting of a control circuit 27 and an optical pickup optical system, an optical recording element according to the present invention, and a reading means consisting of an output circuit 28 and an optical pickup optical system.

Writing is performed as follows. The control circuit 27 controls the oscillation of the semiconductor laser 2B. Therefore, the input information is converted into an optical signal by the control circuit 27 and the half-quad laser 2B. The optical signal 29 passes through the optical pickup optical system shown in FIG. 5, forms an image on the recording layer of the optical disk 1B which is rotating synchronously, and is recorded in color by the coloring mechanism described above.

Reading is carried out as follows. A low-output continuous wave light emitted from the semiconductor laser 2B is used as the reading light. Since the output is low, color recording is not performed during reading. Alternatively, another visible light source may be used as the reading light source.

The reading light beam forms an image on the substrate surface of the optical disk 18 and is reflected, but since the reflectance differs between the coloring point and the non-coloring point, this reflected light is applied to the light receiving surface of the photodiode 25 through the optical pickup optical system. This converts the signal into an electrical signal and reproduces and reads it.

In order to improve the contrast of the reproduced signal and the image quality, it is preferable to provide a reflective layer of metal such as aluminum on the substrate of the optical recording element.

The thickness of the metal reflective layer is 1. (100 Am2,000 A is suitable. Other dielectric mirrors may be used as necessary.

Furthermore, a protective layer may be provided on the surface of the outermost layer to protect the A layer, B layer, light absorption layer, etc.11. Suitable materials for such a protective layer include dielectrics such as 5i02, plastic resins, and other polymerizable LB films.

[Example] Hereinafter, the present invention will be explained in more detail by showing examples. In the following, unless otherwise specified, "part r" means "part by weight J," and "%" means "% by weight."

Synthesis Example 1 (Synthesis Example of Phenolic Compound) One part of the ortho-xylene derivative represented by the phenol Freinz formula (I) (CHz) /7''j was heated with hot air (400°C) using V2O5 (vanadium pentoxide) as a catalyst. -5
00°C), a phthalic anhydride derivative represented by the formula (It) was obtained.

Next, 2 parts of phenol, H and SOa (approx.

Example 1 (1) Method for Forming Layer B A glass (disk) substrate on a disc with a thickness of ioms and a diameter of 180 mm was thoroughly cleaned and then a phenolic compound was prepared using the monomolecular accumulator described above. A monomolecular film mn* of a phenolphthalein derivative was formed.

The monomolecular cumulative film of the phenolphthalein derivative was formed as follows.

After submerging the substrate in water so that it is perpendicular to the water surface, 1 substance of phenolphthalein was added at a concentration of 2 x 10
A 3 mol/4 chloroform solution is dropped onto the water surface to spread a monomolecular film on the water surface.

The surface pressure was set to 30 dyne/cm, and the speed was 2 cm/
A monomolecular cumulative film (Y-type film) of 27 layers was created by moving the substrate up and down with a sin.

By the same method, 1M, 50M, 200 ml, 4
Each sample was obtained by forming a monomolecular cumulative film of 00 layers.

(2) Method for Forming Light-Absorbing Layer Next, 1. A deposited film of vanadium phthalocyanine, which is a light-absorbing substance, was formed on the B layer formed on the glass substrate of each sample obtained in the above (1).

The formation method is to mix 7 parts of vanadium phthalocyanine, 1 part of polyvinyl alcohol as a binder, and 40 parts of water.
Further, the mixture was pulverized and mixed using a ball mill for several hours, and spin-coated onto the B layer of the substrate to obtain a deposited film (M thickness: 0.015 l) of vanadium phthalocyanine dispersed in the binder.

(3) Method for Forming Layer A Next, a deposited film of crystal violet lactone, which is a leuco dye, was formed on the light absorption layer formed on the glass substrate of each sample in (2) above.

The formation method is to mix 7 parts of crystal violet lactone, 1 part of polyvinyl alcohol as a binder, and 100 parts of water, then grind and mix for several hours using a ball mill, and then spin-coat it on the light absorption layer of the substrate and disperse it in the binder. Deposited film of crystal violet lactone (thickness: 1
) was obtained.

(4) Performance test The optical recording element according to the present invention manufactured by the above-mentioned method and the conventional optical disk having the same structure (all constructed without using a monomolecular film or a cumulative film thereof) were used as a comparative example. After recording under the following recording conditions using the information storage device shown in FIG. 5, performance was compared between the two by reading and reproducing.

Recording conditions> Semiconductor laser wavelength: 830 layers m Laser output: 6 to 9 mW Recording frequency: 5 M) Iz Optical disk rotation speed: 1.80 Orpm or higher, reading was performed with a laser output of 1 mW, and the signal/noise ratio was determined. Table 2 shows: Notes to Table 2: The umbrella indicates a comparative example, and each layer was formed by a spin coating method.

From the results in Table 2, when comparing No. 1 (when the B layer consists of a single molecule) and No. 096, it is recognized that No. 1 is significantly superior in signal/noise ratio.
, No. 1 and No. 8 have almost the same film thickness, but this difference in performance occurs in No. 6! This is probably because there are fewer defects such as pinholes.

Similarly, when comparing No. 2 to No. 5 (when 8, 5 consists of a monomolecular cumulative film) and No. 007, No. 12 to No.
It is recognized that 005 is superior in signal ZIa sound ratio.

[Effects of the Invention] As explained above, in the optical recording element according to the present invention, the eight layers are composed of monomolecular films or cumulative films thereof, and the A layer and the light absorption layer are composed of deposited films. , it has the following excellent effects.

(1) Compared to optical recording elements that do not use conventional monomolecular films or their cumulative films, the signal/noise ratio is higher, and the reliability of recording can be improved.

(2) Physical defects such as pinholes in optical recording elements can be significantly reduced.

(3) Higher density recording is possible than with conventional optical recording elements.

(4) It is possible to increase the area of the optical recording element.

(5) Chemical change (synthesis) to a material that has good coloring efficiency and is excellent as a coloring agent, but is difficult to form a monomolecular film or its cumulative Mi layer, or to a derivative that easily forms a monomolecular film or its cumulative layer. There is an advantage that materials which are economically difficult to produce can be used in the deposited film.

CG>81 Since a deposited film is used for a part of the layer body, sensitivity is improved, there is a wide range of material selection during manufacturing, and manufacturing is easy, and the difference between contrast and non-contrast is reduced during reading. It has effects on optical properties such as easy adhesion.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the optical recording element according to the present invention, FIGS. 2(a) to 2(c) are explanatory diagrams showing the recording process of a conventional optical recording element, and FIG. The figure is a schematic cross-sectional view of the monomolecular cumulative film forming apparatus, Is4 (a) to 4 (c) are process diagrams for producing the monomolecular cumulative film, and FIG. 5 is a block diagram of the information storage device.

Claims (1)

[Claims] (1) A usually consists of a leuco form of a colorless or light-colored dye
a B layer made of a phenolic compound that develops color when in contact with the leuco form of the dye; and a light absorption layer interposed between the A layer and the B layer, and (a) the B layer is An optical recording element comprising: a monomolecular film of a phenolic compound or a layer consisting of a cumulative film thereof.