JPS6137482A - Optical recording element - Google Patents

Abstract

PURPOSE:To obtain optical recording elements having high reliability and high packing density by laminating a layer A of color-forming compound and a layer B of assistant color-forming compound with a light-absorbing layer provided and making up the light-absorbing layer of either a monomolecular film or its accumulated film of light-absorbing material. CONSTITUTION:A layer-A 2 of color-forming compound and a layer-B 4 of assistant color-forming compound are laminated. Further a light-absorbing layer 3 is provided on the layer-B 4. The light-absorbing layer 3 is a laminate of either a monomolecular film or its accumulated film, and the layer-A 2 and the layer-B 4 are laminates of laminated films. The light-absorbing layer 3 is supported on a substrate 1, and the substrate, light-absorbing layer, layer B and layer A are laminated in that order. For these reasons, compared to the conventional optical recording element, the titled element has higher packing density and higher signal/noise ratio, thus improving recording reliability.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an optical recording element using an organic material, and more particularly to an optical recording element capable of highly reliable and high-density recording using a highly molecularly oriented organic thin film. [Prior Art] Recently, optical disks have been attracting attention as a central recording device for 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 expected that it will bring In addition, organic materials, which have characteristics such as low cost, ease of manufacture, and high-density recording properties, are attracting attention as recording materials for optical disks. Among the conventional techniques using such organic recording materials, a two-component optical recording element that utilizes a coloring reaction caused by contact between a coloring agent and a periodizing agent has been reported (Nikkei Sangyo Shimbun, 1972).
October 18th, 2016). One example of the conventional optical recording element will be explained based on the drawings. As shown in FIG. It has a structure in which the substrate 1 is laminated on a substrate 1. The coloring agent (leuco body) and the stabilizing agent are colorless or light-colored when each exists alone. When recording on the recording element, a laser beam 8 is irradiated onto a desired position of the light absorption layer 6 as shown in FIG. 2(b).
The portion of the light-absorbing layer that is irradiated with the laser beam absorbs the laser beam, melts, and rips, leaving 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 layer 6, mix through the small holes 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-mentioned optical recording element, in order to achieve high recording density, it is desirable that the light absorption layer 6 be as thin as possible, flat, and without unevenness in film 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 you try to thin it to less than 0 to 500, pinholes tend to occur frequently, and the two components, the coloring agent and the preservative, come into contact at these pinholes and develop color, resulting in a lack of reliability. . Furthermore, 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, each light irradiation The degree of chemical reaction that occurs differs each time. Furthermore, the above-mentioned coating method has drawbacks such as unevenness in film thickness and uneven recording quality when the substrate of an optical disk has a large area. 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 capable of highly reliable and high-density recording. It is an object of the present invention 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 [Operation] That is, the present invention consists of a layer A consisting of a color-forming compound that is usually colorless or light-colored, and a layer Be consisting of an auxochrome compound that develops a color when brought into contact with the color-forming compound. an optical recording layer comprising: a layer of a monomolecular film of a light-absorbing substance or a cumulative film thereof; It is element. The present invention will be explained in detail below. The optical recording element according to the present invention has a structure in which a layer A consisting of a normally colorless or light-colored color-forming compound and an auxochromic compound that develops color when in contact with the 170 color-forming compound are laminated, and a light-absorbing layer is further provided. Basically, it is required to use a combination of substances that develop color when they come into contact with and mix with each other in the A layer and B layer. Specific examples of the normally colorless to light-colored color-forming compound in layer A and the auxochrome compound that develops color when they come into contact with the color-forming compound in layer B, which have such a relationship, are as follows: (a) Acidic substance (layer B) and the leuco form of the dye (dye precursor) that develops color when it comes into contact with the acidic substance (layer A) (b) The leuco form of the dye that develops color when it comes into contact with the oxidizing agent (layer B) and the oxidizing agent (layer A) Layer) (c) A reducing agent (layer B) and a leuco form of a dye that develops color when it comes into contact with the reducing agent (Aff) (d) A reducing agent (layer B) that is reduced like ferric stearate The oxidizing agent (layer A) that develops color (
e) An oxidizing agent (layer B) and a reducing agent (layer A) that develops color when oxidized, such as gallic acid. To give a more detailed example of the case (a) above, the acidic substance in layer B that reacts with the leuco form of the dye to develop color is an aromatic sulfonic acid compound such as benzenesulfonic acid, or an aromatic acid such as benzoic acid. Group carboxylic acids, palmitic acid (CI, H,, C00H), stearic acid ((+v
+13yCOOH), Araxin (CI? H3y)
Examples include higher fatty acid carboxyl compounds such as C00H), phenolic compounds such as pt-butylphenol, α-naphthol, β-naphthol, phenolphthalein, bisphenol A, 4-hydroxydiphenoxide, and 4-hydroxyacetophenone. Next, examples of the leuco dyes in the A layer that react with the acidic substance include triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran. The details of the compounds are shown in Table 1. In the present invention, the A layer and the B layer may be any film as long as it is formed by a conventional coating method, and among them, for example, a layer made of a deposited film such as a vapor deposited film, a coating film, a dipping film, or a laminate. preferable. Note that the thickness of the A layer and the B layer is preferably in the range of 200 Å to 10 μm, and preferably in the range of 1.000 Å to 1 μm. Next, the light-absorbing material used in the formation of the light-absorbing layer in the present invention may be any light-absorbing dye that absorbs infrared rays, such as a melting light-absorbing dye that melts by absorbing infrared rays, or Sublimable light-absorbing dyes that absorb infrared rays and sublimate can also be used, but non-melting dyes and non-sublimating dyes are particularly preferred. Examples of such light-absorbing dyes include metal phthalocyanines such as copper phthalocyanine and vanadium phthalocyanine;
There are xanthine dyes such as fluorescein. Since the light-absorbing layer is formed from a monomolecular film or a layer consisting of a cumulative film thereof, the light-absorbing substance has a parent group, a hydrophobic group, or both groups introduced at appropriate sites within the molecule. It is necessary to use derivatives. Any commonly used hydrophobic group and hydrophilic group can be used, but particularly preferred hydrophobic groups include long-chain alkyl groups having 5 to 30 carbon atoms;
As the parent group, carboxyl groups and metal salts thereof (eg, cadmium salts) are desirable. The thickness of the light absorption layer is desirably in the range of 30 to 1,000 A, preferably in the range of 50 to 200 A. In addition, materials used for the substrate in the present invention include:
Semiconductor materials such as silicon, metal materials such as aluminum, preferably tempered glass, more preferably acrylic (PMMA),
Plastic materials such as polycarbonate (PC), polypropylene, polyvinyl chloride (PVC), polystyrene, and ceramic materials are preferred. One feature of the optical recording element according to the present invention is that the light absorption layer is composed of a monomolecular film of a light-absorbing substance or a layer consisting of a cumulative film thereof. A method for producing a monomolecular film or a cumulative film thereof having such high molecular order and orientation is as follows. For example 1. The Langmuir-Prodgett method (LB method) developed by Lang Uir et al. is used. langmuir
For example, in a molecule with a structure that has a hydrophilic group and a hydrophobic group in the molecule, when the balance between the two (balance of amphiphilicity) is maintained appropriately, the molecule lowers the parent group on the water surface. This is a method of creating and forming a monomolecular film or a cumulative film of monomolecular molecules by utilizing the fact that they form a monomolecular layer. The monomolecular layer on the water surface has the characteristics of a two-dimensional system.When the molecules are sparsely dispersed, the area per molecule is A and the surface pressure is
The two-dimensional ideal gas equation, rIA=kT, holds between , 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 will be strengthened, resulting in a two-dimensional solid "condensed film (or solid 1!J)". Condensed films can be formed on the surface of supports of various materials and shapes, such as plastic substrates and glass substrates. Can be grafted layer by layer. Next, a method for forming a monomolecular film of an organic molecule having a parent group and a hydrophobic group, which is a light-absorbing substance used in the present invention, or a cumulative film thereof will be described in more 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 461O 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 are developed on the water phase 11 with the parent wood 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 aggregation fQ of the membrane material, thereby obtaining a surface pressure (2) proportional to the aggregation state. By moving the partition plate 14, the developed area can be reduced to control the aggregation state of the film material, and the surface pressure can be gradually increased to set a surface pressure n suitable for producing a cumulative film. By gently vertically moving the clean substrate 14 up and down while maintaining this surface pressure, the monomolecular film 16 is transferred onto the substrate. The monomolecular layer 18 is manufactured as described above, and the monomolecular layer cumulative film 17 is formed by repeating the above-mentioned operations to form a desired cumulative number of monomolecular layer cumulative films. For example, when a substrate 15 with a hydrophilic surface is pulled out of water in a direction transverse to the water surface, parent wood groups of the organic molecules are removed from the substrate 15.
A side-facing monolayer 18 is formed on the substrate 15 . 1
When the substrate 15 is moved up and down as described in 11. The monomolecular layer 1B is stacked one by one in each process, and the direction of the film-forming molecules is reversed between the pulling process and the dipping process, so according to this method, between each layer, the parent tree base of the organic molecule and the parent base , a so-called Y-type film is formed in which the hydrophobic groups of 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)'), whereas the opposite A cumulative film in which parent wood groups in all layers face the substrate 15 side is called a Z-type film (FIG. 4(c)). The Z-type membrane

Only when lifting from [1],
Obtained by transferring organic molecules onto the surface of a substrate. 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 Accordingly, it is possible to obtain a recording element having a high-density and high-resolution recording function capable of performing digital recording. Further, as can be seen from the principle, these film forming methods are very simple methods, and a recording element having the excellent recording device 1 as described above can be provided at low cost. The substrate on which the monomolecular film or monomolecular cumulative film is formed in the above-mentioned case 1) 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. Since the monomolecular film is disturbed and a good monomolecular film or monomolecular layer stack cannot be formed, 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 deposit 11A of layer A or layer B is to grind and mix a water mixture obtained by adding a binder and water to the color-forming compound or auxochrome compound using a ball mill or the like, and then apply the mixture to the substrate, etc. The procedure is carried out in the conventional and usual manner after 4 examinations. The binder used in the present invention includes gelatin,
Natural polymers such as starch, cellulose nitrate, cellulose derivatives such as carboxymethyl cellulose, chlorinated rubber,
Semi-synthetic polymers such as natural rubber plastics such as cyclized rubber, polyisobutylene, polystyrene, terpene resins,
Polyacrylic acid, polyacrylic ester, polymethacrylic ester, polyacrylonitrile, polyacrylamide, polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacetal resin, polyvinyl chloride, polyvinylpyridine, polyvinyl carbazole, polybutadiene, polystyrene - Polymerizable synthetic polymers such as butadiene, butyl rubber, polyoxymethylene, polyethyleneimine, polyethyleneimine hydrochloride, poly(2-acryloxyethyldimethylsulfonium chloride), phenolic resins, amine resins, toluene resins, alkyd resins, Condensation polymerization type synthetic polymers such as unsaturated polyester resin, allyl resin 11fi, polycarbonate, polyamide resin, polyether resin, silicone resin, furan resin, thiocol rubber, etc., addition polymerization type resins such as polyurethane, polyurea, epoxy resin, etc. An example of the structure of the optical recording element according to the present invention manufactured by the method described above is as shown in ft51 diagram (a), which includes a layer A 2 made of a color-forming compound and an auxochrome compound. A light absorption layer 3 is further formed on the B layer 4.
The light absorption layer 3 is a monomolecular film or a cumulative film thereof,
The A-layer 2 and the 8-layer 4 are laminates made of deposited films, in which the light-absorbing layer 3 is supported on the substrate 1 and are laminated in the order of substrate/light-absorbing layer/B-layer/A-layer. In this case AW2 and 8 layers 4
The order of substrate/light absorption layer/A layer/B layer may be reversed and the layers may be stacked in this order. Furthermore, to show another example, as shown in FIG. 1(b), A
The layer 2 and the 8 layer 4 are formed into 11i layers, and the light absorption layer 3 is further provided on the A52 to form a laminate, the 8 layer 4 is supported on the substrate l, and the substrate/B layer/A layer/ It is formed by laminating light absorption layers in this order. In this case, as above, A layer 2 and 8 layer 4
Alternatively, the order of substrate/layer A/layer B/light absorption layer may be reversed. Furthermore, in any of the configurations shown in FIGS. 1(a) and 1(b), the laminate may be stacked in two stages and supported on the substrate. Further, since the optical recording element according to the present invention is constructed by laminating the A layer and the B layer in close contact with each other and further providing a light absorption layer on the outside, the light absorption layer is heated by infrared irradiation.
Due to the heat conduction, the color-forming compound in the A layer and the auxochrome compound in the B layer come into contact with each other under heat, and a color-forming reaction progresses, forming a color-forming point at a predetermined position so that information can 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 disk. 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 28. Therefore, the input information is converted into an optical signal by the control circuit 27 and the semiconductor laser 26. The optical signal 28 passes through the optical pickup optical system shown in FIG. 5, forms an image on the recording layer of the optical disc 18 which is rotating synchronously, and is recorded in color by the coloring mechanism described above. Reading is performed as follows. Low-output continuous wave light emitted from the semiconductor laser 26 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 increase the contrast of the reproduced signal and improve 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 preferably 1,000 to 2,000 Å. In addition, a dielectric mirror 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. Materials for such a protective layer include dielectrics such as 5i07, plastic resins, etc. , other polymerizable LB films, etc. are suitable. [Example] Hereinafter, the present invention will be explained in more detail by showing examples. In the following, unless otherwise specified, "part" means "part by weight" and "%" means "% by weight." Synthesis Example 1 (Synthesis example of light-absorbing substance) After mixing and dissolving 10 parts of urea of henadium phlocyanine 1- and 1 part of 10-15% phosphoric acid aqueous solution, 2 parts of phthalic anhydride and VOGI 2 (vanadyl salt) were added. 10 parts and 8 parts of anhydrous phthalcyanine derivative represented by formula (I),
It was heated at 100°C for 5 hours. After cooling, 2% dilute Na
100 parts of an OH aqueous solution is added, hydrolyzed, and then separated by chromatography to obtain the target substance (vanadium phthalocyanine derivative) represented by formula (II) [in formula (2), R represents cmo-c2ude0H(CH2)7fGH3] 0.1 part was obtained. Example 1 (1) Method for forming a light absorption layer A glass (disk) substrate on a disk with a thickness of 10 layers and a diameter of 180 layers was prepared using the above-mentioned single molecule accumulator which had been thoroughly cleaned. A monomolecular cumulative film of a vanadium phthalocyanine derivative, which is a light-absorbing substance, was formed. The monomolecular cumulative film of the vanadium 7-talocyanine derivative was formed as follows. After submerging the substrate in water so that it is perpendicular to the water surface, add vanadium phthalocyanine derivative to a concentration of 2X.
A chloroform solution of 10' mol/31 is dropped onto the water surface to spread a monomolecular film on the water surface, with a surface pressure of 30
dyne/am, and move the substrate up and down at a speed of 2c++/win to form a two-layer monomolecular cumulative film (Y-type Wjt
)It was created. By the same method, samples were obtained in which monomolecular cumulative films of 1 layer, 4 layers, 6 layers, and 8 layers were respectively created. (2) Method for Forming Layer B Next, a deposited film of araxic acid, which is an auxochrome compound, was formed on the light absorption layer formed on the glass substrate of each sample obtained in (1) above. The formation method is to mix 7 parts of alexic acid, 1 part of polyvinyl alcohol as a binder, and 40 parts of water, and then grind and mix for several hours using a ball mill.Then, spin-coat the light-absorbing layer on the substrate to form a binder. A deposited film (thickness: 1 JL) of dispersed alexic acid was obtained. (3) Formation method of A layer Next, the B layer formed on the glass substrate of each sample in (2) above.
A deposited film of crystal violet lactone, a color-forming compound, was formed on top of the layer. 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 using a ball mill for several hours, spin coat on 8 layers of the substrate, and disperse in the binder. Deposition of crystal violet lactone! (Film thickness IJL) was obtained. (4) Performance test An optical recording element according to the present invention manufactured by the above-mentioned method and a conventional optical disk having a similar structure (all constructed without using a monomolecular film or a composite film thereof) were used as a comparative example. 5
After recording under the following recording conditions using the information storage device shown in the figure, the performance of both was compared by reading and reproducing. (Recording conditions) Semiconductor laser wavelength: 830n layer laser output: 6 to 9 mW Recording frequency: 5 MHz Optical disk rotation speed: 1. Reading was performed with a laser output of 1 mW under conditions of 800 rp or more, and the result of determining the signal/noise ratio was Shown in the table. From the results in Table 2, when comparing No. 1 (when the light absorption layer is made of a monomolecular film) and No. 006, it is recognized that No. 1 is significantly superior in signal/noise ratio. No. 1 and No. 8 have almost the same IIA thickness, but
This difference in performance appears to be due to the fact that No. 1 and No. 1 have fewer defects such as pinholes. Similarly, in comparing No. 2 to No. 5 (when the light absorption layer is composed of a monomolecular cumulative film) and No. 017, No. 12
It is recognized that No. 5 is superior in signal/noise ratio. [Effects of the Invention] As explained above, in the optical recording element according to the present invention, the light absorption layer is a monomolecular film or a layer thereof! Layers consisting of li film, layer A and layer B
Since the layer is composed of a deposited film, 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) Since the light absorption layer is not interposed between the A layer and the B layer, coloring efficiency and fidelity are improved. (6) Since the light absorption layer is not interposed between the A layer and the B layer, the recording layer can be made thinner, and higher density recording is possible. (7) Chemically changing (synthesizing) a material that has good coloring efficiency and is excellent as a coloring agent, etc., but is difficult to form a monomolecular film or its cumulative film, or a derivative that easily forms a monomolecular film or its cumulative film. An advantage is that materials that are economically difficult to perform can be used for the deposition 1112. (8) Since a deposited film is used in a part of the laminate, 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 during reading is improved. It has the effect of improving optical properties such as easy adhesion.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are schematic cross-sectional views of an embodiment of an optical recording element according to the present invention, and FIGS. 2(a) to 2(C) are Figures 1 and 3, which illustrate the recording process of a conventional optical recording element, are a diagram of a monomolecular cumulative film forming apparatus.
FIG. 4(a) to FIG. 4(C) are a sectional view of the llfl structure, FIG. 4(a) to FIG. 4(C) are manufacturing process diagrams of a monomolecular cumulative v1 film, and FIG. 5 is a block diagram of an information storage device.

Claims (1)

[Claims] (1) Layer A consisting of a normally colorless or light-colored color-forming compound and layer B consisting of an auxochrome compound that develops color when in contact with the color-forming compound are laminated, and a light-absorbing layer is further provided, and (a) An optical recording element characterized in that the light absorbing layer is composed of a monomolecular film of a light absorbing substance or a layer consisting of a cumulative film thereof.