JPS6137487A - 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 phonolic compound forming a color upon the contact with the leuco dye and a light absorbing layer interposed between the layers A, B and forming the A-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 the light absorbing layer 3 comprising a light absorbable substrance interposed between both layer A, B are provided to form a laminate wherein the A-layer 2 comprises a monomolecular or built-up film and each of the B-layer 4 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 an optical recording device capable of highly reliable and high-density recording using a highly molecularly oriented organic thin film. It is related to the element.

[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.

In particular, a two-component optical recording element that utilizes a color-forming reaction caused by contact between a color former and a periodizing agent has been reported (Nikkei Sangyo Shimbun
(18th October 1981).

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, 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 an attempt is made to reduce the thickness to 0 to 500 A or less, pinholes are likely to occur frequently, and the two components, the coloring agent and the time-setting agent, come into contact with each other 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 upon irradiation with light.

When viewed microscopically, the degree of chemical reaction that occurs each time the light is irradiated differs. 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 is directed to A, which is composed of a leuco form of a normally colorless or light-colored dye.
a layer B consisting 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 layer A and the layer B, and (a) the layer A is made of a dye. An optical recording element characterized in that it is comprised of a monomolecular film of a leuco substance or a layer consisting of a II5I layer 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, generates heat, and melts or sublimates 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, since layer A is formed from a monomolecular film or a layer consisting of a cumulative film thereof, the leuco form of the dye described above has a hydrophilic 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 hydrophilic group, carboxyl groups and metal salts thereof (eg, cadmium salts) are desirable.

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-octyl Catechol, 4.4'-Secondary-butylidene diphenol, 2,2'-dihydroxydiphenyl, 2.
2'-methylenebis(4-methyl6-tert-butylphenol), 2,2'-bis(4'-oxydiphenyl)furopane, 4,4'-isopropylidenebis(2-
Tertiary-butylphenol), 4,4'-secondary-butylidene diphenol, pyrogallol, phloroglucin, phloroglucin carbonate, and the like.

In the present invention, layer B may be any film formed by a conventional coating method, and among these, for example, a layer consisting of a vaporized M film, a coating film, a dipping film, a deposited film such as a laminate, etc. preferable.

The thickness of the A layer and the B layer is desirably in the range of 200 Å to 10 JL, preferably in the range of 1,000 Å to 11 L.

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 single layer 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 90 Å to 1.00 OA, preferably in the range of 14 OA to 40 OA.

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, plastic materials such as acrylic (PMMA), 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 A layer is composed of a monomolecular film of a leuco dye or a layer consisting of fnM layers 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 (La method) developed by ng+5uir et al. The Langmuir-Prodgett method uses, for example, a molecule with a structure that has a hydrophilic group and a hydrophobic group within the molecule, and when the balance between the two (balance of amphiphilicity) is maintained at an appropriate level, the molecule has a parent group on the water surface. This is a method to create a monomolecular film or a cumulative film of monomolecules by using the fact that the monomolecular material turns downward into a monomolecular calendar. When the monomolecular layer on the water surface has the characteristics of a two-dimensional system and zero molecules are sparsely dispersed, the two-dimensional ideal gas equation, nA = kT, is established between the area per molecule A and the surface pressure ■. This results in a ``gas film''. Here, k is Portzmann's constant and T is absolute temperature. If A is made sufficiently small, the intermolecular interaction will be strengthened, resulting in a two-dimensional solid condensation 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, a method for forming a monomolecular film of an organic molecule having both a hydrophilic group and a hydrophobic group, which is a leuco dye used in the present invention, or a cumulative film thereof 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 io 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 hydrophilic groups 12 facing the water phase and the hydrophobic groups 13 facing the gas phase.

Next, in order to prevent the precipitates (organic molecules) from freely diffusing on the aqueous phase 11 and spreading too much, a partition plate (or float) 14 is provided to limit the spread area and control the aggregation state of the membrane substance.
A surface pressure n proportional to the aggregate state is obtained. This partition plate 1
4, the developed area can be reduced to control the aggregation state of the membrane material, and the surface pressure can be gradually increased to set the surface pressure (2) suitable for producing the cumulative (2)q. 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 film 18 is manufactured in the above manner, and the monomolecular layer cumulative film 17 is formed by repeating the above-mentioned operations to form a desired cumulative number of monomolecular layer films fJ1111.

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 1B is formed on the substrate 15. When the substrate 15 is moved up and down as described above.

One monolayer 1B is stacked in each process.
, '~11, Go, - Since the orientation of the film-forming molecules is reversed between the pulling process and the dipping process, according to this method, between each layer, the hydrophilic group and the parent group of the organic molecule, and the hydrophobic group and the hydrophobic group of the organic molecule. A so-called Y-shaped film is formed in which the two sides 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 orientation of the film-forming molecules even if they are accumulated, and in all cases, the hydrophobic group is the substrate! An X-type film is formed that faces the substrate 15 side (Fig. 4(b)).On the other hand, a cumulative film in which the parent bases of all layers face the substrate 15 side is called a Z-type film (Fig. 4(b)). C) ).

The Z-type film is obtained by transferring organic molecules onto the surface of the substrate only when the substrate 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 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 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 monomolecular film or monomolecular cumulative film in the present invention is formed as described above 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 Since the 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 deposited film of layer B or light absorption layer is to grind and mix a water mixture in which a binder and water are added to the phenolic compound or light absorption substance using a ball mill, etc. This is done by applying it on top using the conventional method.

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, polyvinylcarbazole,
Polymerizable synthetic polymers such as polybutadiene, polystyrene-butadiene, butyl rubber, polyoxymethylene, polyethyleneimine, polyethyleneimine hydrochloride, poly(2-acryloxyethyldimethylsulfonium chloride), phenolic resins, amino resins, toluene resins, alkyds Condensation polymerization type synthetic polymers such as resins, unsaturated polyester resins, allyl resins, polycarbonates, polyamide resins, polyether resins, silicone resins, furan resins, thiokol rubber, etc., addition polymerization type resins such as polyurethane, polyurea, epoxy resins, etc. can be mentioned.

An example of the structure of an optical recording element according to the present invention manufactured by the method described above is shown in FIG. 1, as shown in FIG. 8 layers consisting of phenolic compounds 4 and a light-absorbing substance interposed between layer A and layer B 1
The A layer 2 is a monomolecular film or a cumulative film thereof, and the 8 layers 4 and the light absorption layer 3 are stacked films made of deposited films. /B layer/light absorption layer/A layer are laminated in this order.

Furthermore, as another example, the A layer of the laminate may be supported on a substrate, and the laminate may be laminated in the order of substrate/A layer/light absorption layer/B layer, or the laminate may be stacked in two layers. The bottom A layer or BW 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 BW by a light absorption layer, the AW The color-forming compound contacts the eight layers of time-setting compounds, a color-forming reaction progresses, a color-forming point is formed at the position, and 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 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 semiconductor 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 18 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 passed through the optical pickup optical system to the light receiving surface of the photodiode 25. It is converted into an electrical signal by applying it to the electrical signal, and then read out and reproduced.

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 A to 2,000 A. 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, the 8th layer, the light absorption layer, etc. Calendar materials include dielectrics such as 5i02, plastic resins,
Other polymerizable LB films and the like are suitable.

[Example] Hereinafter, the present invention will be explained in more detail by showing examples. In the following, unless otherwise specified, "1 part" means "part by weight" and "%" means "% by weight."

Synthesis Example 1 (Synthesis example of leuco form of dye) One part of m-aminobenzoic acid derivative represented by crystal biolate lactone (formula (I)) and formula (II)
1 part of Michler's hydrol represented by H ) was added to 1 part of acid) and refluxed for 8 hours to produce a triphenylmethane derivative represented by formula (II) (C) 12), CH3.

Next, the triphenylmethane derivative of the product was treated with lead dioxide (
1 part) after heating in the presence of sulfuric acid for 3 hours.

A crystal violet lactone derivative represented by formula 1) % formula % was obtained.

Next, by adding an aqueous solution of caustic soda to this and cyclizing it, formula (V) (C)I, ), C)l is obtained.

A crystal violet lactone derivative represented by 0.
Got 2 copies.

Example 1 (1) Method for forming 3 layers A glass (disc) substrate on a circular plate with a thickness of 10mm-1 and a diameter of 180+a+++ was thoroughly cleaned.Next, 7 parts of phenolphthalein, a phenolic compound, As a binder, 1 part of polyvinyl alcohol and 40 parts of water were mixed, and the mixture was ground and mixed using a ball mill for several hours, and the mixture was spin-coated onto a substrate to form a deposited film of phenolphthalein dispersed in the binder with a thickness of Cn=2. Each sample in which IJL) was formed was obtained.

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

The formation method includes 7 parts of vanadium phthalocyanine and 1 part of polyvinyl alcohol as a binder. Mix 4 parts of water,
The mixture was pulverized and mixed using a ball mill for several hours, and spin-coated onto 8 layers of a substrate to obtain a deposited film of vanadium phthalocyanine dispersed in a binder (thickness: 0.015 l).

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

The method for forming a monomolecular cumulative film of the crystal violet lactone derivative was performed as follows.

After submerging the substrate in an acidic solution with a pH of 4 so that the substrate on which the three layers and the light absorption layer were formed is perpendicular to the water surface, a crystal violet lactone derivative was added at a concentration of 2 x 10''.
mol/f1. A chloroform solution of 0 is added dropwise onto the water surface, and a monomolecular film is developed on the water surface at a surface pressure of 30 dyne.
/crs, and the substrate was moved up and down at a speed of 2 cm/win to measure the cumulative amount of single molecules accumulated in each layer shown in Table 2 (Y
A mold film) was prepared for each sample.

(0 performance test) The optical recording element according to the present invention manufactured by the above-mentioned method and the optical disk according to the conventional similar structure (all constructed without using a monomolecular film or a cumulative film thereof) as a comparative example were tested in the fifth test. 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: 830+s+s Laser output: 6 to 9I Recording frequency: a5MHz Optical disk rotation speed: Reading was performed at a laser output of llllw under conditions of 1,800rpra or higher, and the signal/noise ratio was determined. Table 182 shows this.

Notes to Table 2...Pig 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 A layer is made of a monomolecular film) and No. B, it is recognized that No. 1 is significantly superior in signal/noise ratio. N
O, 1 and No, B have almost the same film thickness, but this difference in performance appears to be because No, 1 has fewer defects such as pinholes.

Similarly, in the comparison between No. 2 to No. 5 (when the A layer consists of a monomolecular cumulative film) and No. 087, No. 2 to No.
, 5 is found to be superior in signal/noise ratio.

[Effects of the Invention] As explained above, in the optical recording element according to the present invention, the A layer is composed of a monomolecular film or a cumulative film thereof, and the B layer and the light absorption layer are composed of a salt m film. Therefore, it has the following excellent effects.

(1) The signal/noise ratio is higher than that of optical recording elements that do not use conventional monomolecular films or their cumulative films.

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) A material that is excellent as a preservative among phenolic compounds and as a light absorbing agent among light-absorbing substances, but is difficult to form a monomolecular film or a cumulative layer thereof, or a monomolecular film or a cumulative layer thereof. There is an advantage that materials that are difficult to chemically change (synthesize) into derivatives that can easily form layers can be used in the deposited film due to cost considerations.

(6) Since a deposited film is used as a part of the laminate, the 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, and Fig. 4(a) to Fig. 4(
C) is a manufacturing process diagram of a monomolecular cumulative a film, and FIG. 5 is a block diagram of an information storage device.

Claims (1)

[Claims] (1) A usually consists of a leuco form of a colorless or light-colored dye
a layer B consisting 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 layer A and the layer B, and (a) the layer A is made of a dye. An optical recording element comprising: a monomolecular film of a leuco substance or a layer consisting of a cumulative film thereof.