JPS6137484A - Optical recording element - Google Patents

Abstract

PURPOSE:To obtain highly reliable and densely recordable optical recording elements by providing a layer A of pale leuco dye, a layer B of phenol compound which develops the color of said leuco dye and a light-absorbing layer existing between the layer A and the layer B, and making up both layer A and light- absorbing layer of either a monomolecular film or an accumulated film of the former respectively. CONSTITUTION:An optical recording element is composed of a layer-A 2 of leuco dye, a layer-B 4 of phenol compound and a light-absorbing material existing between the layer A and the layer B. The layer A and the light-absorbing layer 3 are laminates of either a monomolecular film or an accumulated film of the former. The layer B 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. Consequently, the titled optical recording element has higher packing density and also higher signal/noise ratio than the conventional element, 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 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, a two-component one-light recording element that utilizes a coloring reaction caused by contact between a coloring agent and a periodizing agent has been reported (Nikkei Sangyo Shimbun, 1932).
(October 18, 2008).

An example of the conventional optical recording element will be explained based on a drawing.As shown in ffs 2 IN (a), a color forming agent layer 7 and a moderating agent layer 5 are separated by a light absorbing layer 6 and are formed on a substrate 1. 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, as shown in FIG. 2(b), when a laser beam 8 is irradiated to a desired position of the light absorption N6,
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 these 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 was made to reduce the thickness to 0 to 500 A or less, pinholes would occur frequently, and the two components, the coloring agent and the time-setting agent, would 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 in the film be uniform, that there are no pinholes or uneven film thickness, and that the film thickness be as thin as possible to achieve high recording density and high performance. The present invention has been made in view of the demand for reliability, 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.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. (b) The light-absorbing layer is a monomolecular film of a light-absorbing substance or a cumulative film thereof; This is an optical recording element characterized in that it is composed of a layer consisting of.

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 in contact with the leuco form of the dye, and an AH and a layer B. It basically consists of a light absorbing layer that is interposed between the layers and 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 the A layer is formed from a monomolecular film or a layer consisting of a cumulative film thereof, the leuco form of the dye described above has parent wood groups, a* groups, or both groups at appropriate sites within the molecule. It is necessary to use the introduced derivative.

Any commonly used hydrophobic group and parent tree 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.

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-hydroxycyphenophenol. cyto, 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'-sec-1y-butylidene diphenol, 2,2'-dihydroxydiphenyl, 2
．． 2'-methylenebis(4-methyl-6-tert-
butylphenol), 2,2'-bis(4'-oxydiphenyl)propane, 4,4'-isopropylidene bis(
2-tert-butylphenol), 4,4'-secondary-butylidene diphenol, pyrogallol, phloroglucin, phloroglucin carboxylic acid, and the like.

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

The thickness of the A layer and the B layer is desirably in the range of 200 A to Ig, and preferably in the range of 1,000 A 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.

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 parent tree group can be used, but particularly preferred hydrophobic groups include long-chain alkyl groups having 5 to 3 degrees of carbon atoms;
The parent group is preferably a carboxyl group and its metal IM (eg, cadmium salt).

The thickness of the light absorption layer is preferably in the range of 30A to 1.00OA, preferably in the range of 50 to 200A.

In addition, the materials used for the substrate in the present invention include:
Semiconductor materials such as silicon, metal materials such as aluminum, preferably reinforced glass, and plastic materials such as acrylic (PMMA), polycarbonate (PC), polypropylene, polyvinyl chloride (PVC), polystyrene, etc.
Ceramic materials and the like are preferred.

In the optical recording element according to the present invention, the A layer is composed of a monomolecular film of a leuco dye or a cumulative film thereof, and the light absorption layer is composed of a monomolecular film of a light absorbing substance or a cumulative film thereof. This is one of its characteristics.

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 (La method) developed by Langmuir et al. is used. langmuir
For example, in the Prodget method, when a molecule has a parent wood group and a hydrophobic group within the molecule, and the balance between the two (amphipathic balance) is maintained appropriately, the molecule will hold the parent wood group on the water surface. This is a method of creating a monomolecular film or a cumulative film of monomolecular molecules by utilizing the fact that the monomolecular layer forms 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 true, 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 the "a contraction" of a two-dimensional solid ( 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 thereof of an organic molecule having a leuco form of a dye or a light-absorbing substance which is a parent wood group and a hydrophobic group used in the present invention 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 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 molecule develops on the aqueous phase 11 with the -hydrophilic group 12 directed toward the aqueous phase and the hydrophobic group 13 directed toward 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.
1 to control the aggregation state of membrane materials by limiting the development area by setting
Then, a surface pressure n proportional to the aggregate state is obtained. The partition plate 14 is moved to reduce the developed area, control the aggregation state of the film material, gradually increase the surface pressure 1, and set the surface pressure 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 1B is transferred onto one substrate. The monomolecular film 1B is manufactured in the above manner, but the monomolecular layer stack v1 film 17
By repeating the above operations, a monomolecular layer cumulative film having a desired number of layers is formed.

For example, when the substrate 15 whose surface is woody is pulled out of water in a direction across the water surface, the woody groups of the organic molecules are transferred to the substrate I5.
A side-facing monolayer I6 is formed on the substrate 15. As mentioned above, when the plate 15 is moved up and down, 1
The monomolecular layers 16 are stacked one by one, and the direction of the dimolecules is reversed in the pulling process and dipping process, so in this method, between each layer, the parent wood group of the organic molecule and the parent wood group of the organic molecule, A so-called Y-shaped film is formed in which the hydrophobic groups face each other (Fig. 4(a)).

The Y-type film is strong because the parent groups and hydrophobic groups of 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 formed JIQ 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)). A cumulative film in which all the layers have parent wood groups facing the substrate 15 side is called a Z-type film (FIG. 4(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 stack formed on the substrate by the above method have high density and a high degree of order and orientation. , a recording element having a high-density and high-resolution recording a-moat usable for photothermal recording 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 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 is to grind and mix a water mixture obtained by adding a binder and water to the phenolic compound using a ball mill, etc., and then coat it on a substrate etc. using a conventional method. Wear it and do it.

The binder used in the present invention includes gelatin,
Natural polymers such as starch, cellulose nitrate, cellulose derivatives such as carboxymethyl cellulose, pentachloride rubber,
Semi-synthetic polymers such as natural rubber plastics such as cyclized rubber, polyisobutylene, polystyrene, terpene resins,
Polyacrylic acid, polyacrylic S 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 the optical recording element according to the present invention manufactured by the method described above is shown in FIG. 1, as shown in FIG. 4 and a light absorbing layer 3 made of a light absorbing substance interposed between the A layer and the B layer, the A layer 2 and the light absorbing layer 3 are monomolecular films or their cumulative films, and the 8 layer 4 is a deposited film. It is a laminate, in which a B layer 4 is supported on a substrate 1, and the substrate/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 or more stages to form the bottom layer. A layer or B
The layer may be supported on a 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 reaction progresses, forming a color point at the position and recording information.

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 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 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. Materials for such a protective layer include dielectrics such as 5i02, plastic resins, and other materials. A polymerizable LB film or the like is suitable.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. In addition, unless otherwise stated below, "Department" means "
"Gravity part" and "%" represent "gravity 1%".

Synthesis example 1 (synthesis example of light-absorbing substance) Muftalocyanine 1゛ Heurea 10 parts and 1
After mixing and dissolving 1 part of 0-15% phosphoric acid aqueous solution, 2 parts of phthalic anhydride and 'V2C statement.

(/henadyl salt) 10 parts and 8 parts of anhydrous phthalcyanine conductor represented by formula (1) were added,
It was heated at 100°C for 5 hours. After cooling, 2%'R3
100 parts of NaOH aqueous solution was added, hydrolyzed, and separated by chromatography to form the formula (II) K" NN △7(・)I(CHL), CH.

0.1 part of the target substance (/<nadium phthalocyanine derivative) represented by ] was obtained.

Synthesis Example 2 (Synthesis example of leuco form of dye) One part of the aminobenzoic acid derivative represented by the formula (III) and the leuco-aminobenzoic acid derivative represented by the formula (1) Mix 111 parts of Michlage dihydro-1 with oN (nitrobenzene) solvent and add % SOH (as para-toluene sulfonate) I.

Add 1 part of acid) and reflux for 8 hours. Formula (Vl (CH2), 70H3° A triphenylmethane derivative represented by was produced.

Next, the triphenylmethane derivative of the product was converted into lead dioxide (
After heating in sulfuric acid for 3 hours in the presence of part 1), a Xosta J Shiba-iorezomulactone derivative of the formula (Vl) (C:Hz)z7CH3 was obtained.

Next, by adding a caustic soda aqueous solution to this and cyclizing it, the formula (■) ■ (CH,), 7CH was obtained.

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

Example 1 (1) Method for Forming Layer B A well-cleaned glass (disc) substrate on a disk with a thickness of 10 mm and a diameter of 180 nm was prepared by adding 7 parts of phenolphthalein, a zero-order phenolic compound, and a binder. 1 part of polyvinyl alcohol and 40 parts of water were mixed together 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 pine goo (IIQ thickness of 1 lumen). ) were obtained.

(2) Method of forming a light-absorbing layer Next, a light-absorbing substance is coated on the B layer formed on the glass substrate of each sample obtained in (1) above using the monomolecular accumulator described above. A monomolecular cumulative film of a certain vanadium phthalocyanino derivative was formed.

The monomolecular cumulative film of the vanadium phthalocyanine 5f5 conductor was formed as follows.

After layer B was formed, the substrate was submerged in water so that the plate was perpendicular to the water surface, and then a vanadium phthalocyanine derivative was made into a chloroform solution with a concentration of 2 × 10° 3 mol/9.0% and dropped onto the water surface. 0 Spreading a monomolecular film on the water surface
The surface pressure was set to 30 dyne/am, and the speed was 2 cm/
Single molecules accumulated in each layer shown in Table 2 by moving the substrate up and down at min 11! J (Y type membrane) was prepared for each sample.

(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 of pH 4 so that the plate on which the B layer and light absorption layer were formed is perpendicular to the water surface, crystal violet lactone derivative was added at a concentration of 2 x 10.
” Make a chloroform solution of mol/4 and drop it onto the water surface to spread a monomolecular film on the water surface.
/c+w, and the substrate was moved up and down at a speed of 2 cm/m:n 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 The optical recording element according to the present invention manufactured by the above-mentioned method and the conventional optical disc having the same structure (all constructed without using monomolecular Hi or its cumulative film) 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 na + Laser output: 6 to 91 Recording frequency: 5 MHz Optical disk rotation speed: 1.80 Orpm or higher, readout was performed with a laser output of 1 + nW, and the signal/noise ratio was determined. Table 2 shows the results. show.

The second table shows comparative examples, and each layer was formed by a spin coating method.

Comparing No. 1 (when the A layer and light absorption layer are made of monomolecular film) and No. 8 from the results in Table 2, No. 1
It is recognized that the signal/lone ratio is significantly better. No. 1 and No. 016 have approximately the same thickness as the turning film, but
This difference in performance appears to be due to the fact that N001 has fewer defects such as pinholes.

Similarly, in comparing No. 2 to No. 5 (when the A layer and the light absorption layer are composed of monomolecular cumulative films) and No. 67, N.
It is recognized that No. o, 2 to No. 5 are 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 and the light absorption layer are composed of a monomolecular film or a cumulative film thereof, and the B layer is composed of a deposited film. , it has the following excellent effects.

(1) Conventional monolayer or its cumulative aF! The signal/noise ratio is higher than that of an optical recording element that does not use an optical recording element, and recording reliability 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) Among phenolic compounds, chemical changes (chemical changes) to materials that are excellent as seasoning agents, but which are difficult to form Qi molecules or their cumulative layers, or to derivatives that are easy to form single molecules or their cumulative layers ( This has the advantage that materials that are economically difficult to synthesize can be used in the deposited film.

(6) Since the deposited material is used in a part of the laminate, the sensitivity is improved, there is a wide range of material selection during manufacturing, and manufacturing is easy. It has effects on optical properties such as easy contrast differences.

[Brief explanation of drawings]

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, f? Figure 14 (a) - 4th
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 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. (b) 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; .