JPS6137475A - Optical recording element - Google Patents

Abstract

PURPOSE:To obtain highly reliable and densely recordable optical recording element by providing constituent layers such as a layer A of color-forming compound, layer B of assistant color-forming material and a light-absorbing layer existing between the layer A and the layer B and making up both layers A, B of either a monomolecular film or an accumulated film. CONSTITUTION:The titled optical recording element is composed of a layer-A 2 of color-forming compound, a layer-B 4 of assistant color-forming compound and a light-absorbing layer 3 of light-absorbing material existing between the layers A and B. The layer-A 2 and layer-B 4 are laminates of monomolecular film or accumulated film of the former, and the light-absorbing layer 3 is a laminate of laminated films. The layer-B 4 is supported on a substrate 1 and the substrate, layer B, light-absorbing layer and layer A are laminated in that order. As a result, as compared to the conventional optical recording element, the titled element has the higher packing density and higher signal/noise ratio thus improving recording reliability.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an optical recording element using organic materials, 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.

[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 large amount of documents, literature, etc. can be recorded (or recorded) on a single optical disc, and 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 this will bring about In addition, as recording materials for optical discs, organic materials are attracting attention because they have characteristics such as low cost, ease of manufacture, and high-speed recording performance.

Among the conventional techniques using such organic recording materials, a two-component optical recording element that utilizes a color reaction caused by contact between a color former and an auxiliary has been reported (Nikkei Sangyo Shimbun, 1972).
IO month 18th].

Optical recording; (Explaining one example of triplets based on the I:2 plane, as shown in FIG. It has a structure in which the substrate 1 is laminated on the substrate 1.

The coloring agent (leuco substance) and the auxiliary colorant are light or pale in color 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 color forming agent and the auxiliary color agent, which were separated by the light absorbing 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 auxiliary colorant, come into contact with each other at these 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 drawbacks such as unevenness in film thickness and poor recording quality when the substrate area of an optical disk is increased.

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 there is no unevenness in the film thickness, and that the film thickness be as thin as possible to achieve high-pressure thinning 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. Another object of the present invention is to provide an optical recording element that is easy to manufacture and inexpensive. Yet another object of the present invention is to provide a large-area optical recording element.

[Means for Solving the Problems] and [Operations] In other words, the present invention consists of a layer A consisting of a color-forming compound that is usually colorless or light-colored, and a layer B consisting of an auxochrome compound that develops a color when it comes into contact with the color-forming compound. and a light absorption layer interposed between the A layer and the B layer, and (a) the A layer is a monomolecular film of a color-forming compound or a cumulative film thereof, and (b) the B layer. is an optical recording element characterized by comprising a monomolecular film of an auxochrome compound or a layer consisting of a cumulative N thereof.

The present invention will be explained in detail below.

The optical recording element according to the present invention has a layer B between an AH composed of a color-forming compound that is usually colorless or light-colored, and a layer B composed of an auxochromic compound that develops a color when brought into contact with the color-forming compound.
It consists of a structure in which a light absorption layer is interposed, and the A
Layer and B layer are in contact with each other,! Basically, it is required to use a combination of substances that develop color when added. 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 B) A layer) (c) Reducing agent (B
layer) and a leuco form of dye that develops color when it comes into contact with the reducing agent (layer A) (d) reducing agent (layer B) and an oxidizing agent (layer A) that develops color when reduced, such as #2 stearic acid. layer)
(e) An oxidizing agent (layer B) and a reducing agent (layer A) which develops a color when thickened, such as gallic acid.

To give a more detailed example of the case (a) above, the acidic substances in the B layer that react with the leuco form of the dye and develop color include aromatic sulfonic acid compounds such as benzenesulfonic acid, aromatic acids such as benzoic acid, etc. group carboxylic acids, palmitic acid (
C:,,H,,C00)I), stearic acid (C1?H
15COOH), araxic acid (C,9H,fcOOH)
), 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. Details of the compounds are shown in Table 1.

In the present invention, both the A layer and the B layer are formed from a monomolecular film or a layer consisting of a cumulative film thereof. It is necessary to use a derivative into which a group, a hydrophobic group, or both groups are introduced.

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 A layer and the B layer is desirably in the range of 200 Å to 100 Å, preferably in the range of 1,000 Å to 1 p.

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 metal phthalocyanines such as copper phthalocyanine and vanadium phthalocyanine, and xanthine dyes such as fluorescein.

The light-absorbing layer may be any film formed by a conventional coating method, and among these, a layer made of a deposited film such as a vapor-deposited film, a coating film, a dipping film, or a laminate film is preferable.

The thickness of the light absorption layer is preferably in the range of 90A to 1000A, preferably in the range of 140A to 40OA.

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, more preferably acrylic (PMMA),
Plastic materials such as polycarbonate (PC), polypropylene, polyvinyl chloride (PVC), polystyrene, and ceramic materials are preferred.

In the optical recording element according to the present invention, layer A is composed of a monomolecular film of a color-forming compound or a cumulative film thereof, and layer B is composed of a monomolecular film of an auxochrome compound or a cumulative film thereof. This is one of its characteristics.

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 (LB method) developed by Ngmuir et al. is used. The Langmuir-Prodgett method is based on the Langmuir-Prodgett method. For example, when a molecule has a parent tree group and a hydrophobic group in its molecule, and the balance between the two (balance of amphiphilicity) is maintained appropriately, the molecule will react to 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. A monolayer on the water surface has the characteristics of a two-dimensional system. When the molecules are sparsely dispersed, the two-dimensional ideal gas equation, rlA=kT, holds true between the area A per molecule and the surface pressure n, resulting in a "gas film'°. Here, k is Portzmann's constant, T, is the absolute temperature. If A is made sufficiently small, the intermolecular interaction becomes strong, resulting in a two-dimensional solid "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, a method for forming a monomolecular film or a cumulative film thereof of an organic molecule having both a parent group and a hydrophobic group, which is a color-forming compound or an auxochrome compound used in the present invention, will be described in more detail.

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

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, to prevent the precipitates (organic molecules) from freely diffusing and spreading on the aqueous phase 11, a partition plate (or float) 14 is provided to limit the spread area and control the Hλ film material aggregate m1. , obtain a surface pressure ■ proportional to its collective state. By moving the partition plate 14 of No. 9 to reduce the developed area and gradually increase the surface pressure from the 11th point I onwards, it is possible to set the 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.

Although the monomolecular film 16 is manufactured in the above manner, the monomolecular layer cumulative film 1
In step 7, by repeating the above operations, a desired cumulative number of monomolecular layers are formed.

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 . 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 allows each living room to be In this case, a so-called Y-type film is formed in which the hydrophilic and parent groups of the organic molecules and the hydrophobic groups of the organic molecules face each other (Fig. 4(a)).

The Yyrn mouth 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 the films are accumulated, and an X-type film is formed in which the hydrophobic groups face the substrate 15 in all layers (FIG. 4(b)). On the other hand, a cumulative film in which all parent groups face the substrate 15 side 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 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 principle, 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, Since the molecular film is disturbed and a good monomolecular film or monomolecular layer stack cannot be formed, it is necessary to use a substrate whose surface is III-level clean.

A monomolecular film or a monomolecular layer stack on a substrate is sufficiently strongly fixed and rarely peels or peels off from the substrate.
An adhesive layer can also be provided between one or monolayer stacked films. 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 the light absorption layer is to grind and mix a water mixture in which a binder and water are added to the light absorbing substance using a ball mill or the like, and then apply it on a substrate, etc. using a conventional conventional method. Paint it with.

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

An example of the structure of the optical recording element according to the present invention manufactured by the method described above is shown in FIG. 1, as shown in FIG. and Bq, the A layer 2 and 3 layer 4 are a monomolecular film or a laminate thereof, and the light absorption layer 3 is a laminate consisting of a deposited film. Three layers 4 are supported on a substrate 1 and are laminated in the order of substrate/B layer/light absorption layer/A layer.

Further, as another example, the A layer of the laminate may be supported on a substrate and laminated in the order of substrate/AA layer light absorption W/BF3, or two laminates may be stacked on top of each other to form the lowest layer A. The layer or B) W 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 of layer A and the auxochrome compound of BB come into contact, a color-forming reaction progresses, and a color-forming point is formed at the 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 and 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 26. 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-power continuous wave light emitted from the semiconductor laser 26 is used as reading light. This is because, 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 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, B layer, light absorption layer, etc. 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" means "part by weight" and "%" means "15%".

Synthesis Example 1 (Synthesis Example of Color-Forming Compound) Synthesis Example of Crystal Violet I Lactone, Conductor One part of the m-7 minobenzoic acid derivative represented by the formula (I), and one part of the m-7 minobenzoic acid derivative represented by the formula (II)
) CHK with 1 part of Michler's Hydrol indicated by H as
Add 1 part of H (para-toluenesulfonic acid) and reflux for 8 hours to obtain the formula (ffI) (CH2), 7CH.

A triphenylmethane derivative represented by was produced.

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

A crystal violet lactone derivative represented by the formula (W) CH3 (OH2), 7CH3 was obtained.

Next, a caustic soda aqueous solution was added to this and cyclized to obtain the formula (V) (C:)12), 7CH.

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

Example 1 (1) Method for Forming Layer B A glass (disk) substrate on a disk with a thickness of 10 mm and a diameter of 180 mm was thoroughly cleaned. Next, the monomolecular group Jj mentioned above
A monomolecular cumulative film of araxic acid, an auxochrome compound, was formed using the 'i device.

The method for forming the monomolecular cumulative film of alaxic acid was performed as follows.

After submerging the substrate in water so that it is perpendicular to the water surface, add 7 rachidic acid at a concentration of ? A chloroform solution of ×10°3 mol/liter is dropped onto the water surface to spread a monomolecular film on the water surface. Set the surface pressure to 30 dyne/cm,
The substrate was moved up and down at a speed of 2 cm/min to create a monomolecular cumulative film (Y-type film) having 27 layers.

By the same method, samples of monomolecular cumulative films of 1 layer, 50 layers, 200 layers, and 400 layers were obtained.

(2) Method for forming a light-absorbing layer Next, a deposited film of vanadium phthalocyanine, which is a light-absorbing substance, was formed on the B5 formed on the glass substrate of each sample prepared in step (1) above. .

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 ground and mixed for several hours using a ball mill, and then spin-coated onto the B layer of the substrate to form a deposited film of vanadium phthalocyanine (7) dispersed in the binder (thickness: 0.015
g) Obtained.

(3) Method for Forming Layer A Next, on the light absorption layer formed on the glass substrate of each sample in (2) above, a crystal violet lactone derivative, which is a color-forming compound, was deposited on the light absorption layer formed on the glass substrate of each sample 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 is described in 5. It was done as follows.

After submerging the substrate in an acidic solution of PH4 so that the substrate on which the B layer 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'.
A chloroform solution of mol/u is dropped onto the water surface to spread a monomolecular film on the water surface. Surface pressure 30dyne/
cm, and the substrate was moved up and down at a speed of 2 cm/+sin to create a monomolecular cumulative film (Y-type film) for each sample, which was accumulated in each layer shown in Table 2.

(4) Performance test An optical recording element according to the present invention manufactured by the above-mentioned method and an optical disc according to a conventional similar structure r&, (all constructed without using a monomolecular film or a layer thereof) as a comparative example was recorded under the following recording conditions using the information storage device shown in FIG. 5, and then read and reproduced to compare the performance of the two.

<Recording conditions> Semiconductor laser wavelength 830n layer laser output 6 to 9+oW Recording frequency 5 MHz Optical disk rotation speed 1.80 Orpm or higher, readout was performed with a laser output of 1+mW, and the results of calculating the signal/noise ratio are shown in Table 2. Shown below.

Notes to Table 2: This book shows comparative examples, and each layer was formed by a spin coating method.

From the results in Table 2, when comparing No. 1 (a famous bathhouse where the A layer and the free layer are made of a single monomolecular film) and No. 8, there was a difference in performance despite the fact that This is probably because N001 has fewer defects such as pinholes.

Similarly, in comparing No. 2 to No. 5 (A layer and Makuei - when one layer consists of a monomolecular cumulative film) and No. 7,
No, 2 to No, 5 is the signal/! It is recognized that the I tone ratio is excellent.

[Effects of the Invention] As explained above, in the optical recording element according to the present invention, the A layer and the third layer are composed of a monomolecular film or a cumulative film thereof, and the light absorption layer is composed of a layer 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) Sensitivity is improved, there is a wide range of materials to choose from during manufacturing, manufacturing is easy, and there are effects in terms of optical properties such as the difference between contrast and non-contrast being easily discernible during reading.

[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 shows a single molecule cumulative M
Schematic cross-sectional view of the n'2 forming device, FIGS. 4(a) to 4
Figure (c) is a manufacturing process diagram of a monomolecular cumulative film, and Figure 5 is a block diagram of an information storage device.

Claims (1)

[Claims] (1) A layer consisting of a normally colorless or light-colored color-forming compound, a B layer consisting of an auxochrome compound that develops color when in contact with the color-forming compound, and light absorption interposed between the A layer and the B layer. (a) the A layer is a monomolecular film of a color-forming compound or a cumulative film thereof; and (b) the B layer is a monomolecular film of an auxochrome compound or a cumulative film thereof. An optical recording element comprising: .