JPH0475836B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an optical recording medium, and particularly to an optical recording medium suitable for optical writing using an infrared laser. [Prior Art] Recently, optical disks have been attracting attention as a central part of office automation. Optical disks can store a large amount of documents, documents, etc. on a single disk, so documents, etc. can be organized and managed efficiently in an office. Various types of recording elements have been studied for this optical disk, but those using organic materials are attracting attention because of their cost and ease of manufacture. Diacetylene derivative compounds are known as organic materials for such recording elements, and a recording technology for use as a laser recording element was disclosed in Japanese Patent Laid-Open No. 147807/1983, focusing on the thermochromic properties of these compounds. ing. However, this specification does not mention what kind of laser was used or should be used, and merely states that recording was performed using a laser. The present inventors investigated laser recording of this diacetylene derivative compound using various lasers, and found that although thermochromic recording is possible using a large, high-output laser such as an argon laser, a small and relatively Low power semiconductor laser (wavelength
It was confirmed that laser recording cannot be performed when using a wavelength of 800 to 850 nm). However, for practical recording media such as optical disks, it is required that optical writing be possible using a small, low-output semiconductor laser. Furthermore, the recording layer of the recording medium disclosed in JP-A-56-147807 is composed of microcrystals of diacetylene derivative compounds dispersed in a binder, and the orientation of these compounds within the recording layer is random. Therefore, phenomena such as light absorption and reflectance differing depending on the location and the degree of chemical reaction occur, making it not necessarily suitable for high-density recording. [Problems to be Solved by the Invention] The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide an optical recording medium that can be optically written with a small and lightweight semiconductor laser. It is about providing. Another object of the present invention is to provide an optical recording medium capable of high-density, high-sensitivity, and high-speed recording. Still another object of the present invention is to provide an optical recording medium with excellent stability and high quality. Another object of the present invention is to provide an optical recording medium having a recording layer that has particularly excellent film formability and does not easily peel or peel off. [Means for Solving the Problems] The above object is achieved by the following present invention. That is, the present invention comprises a monomolecular film of a diacetylene derivative compound or a cumulative film thereof (film A), and a monomolecular film of a compound having a skeleton represented by the following general formula (1) or a cumulative film thereof (film B). The optical recording medium is characterized in that it is laminated and has two or more bonding surfaces between the A film and the B film. [However, in the formula, l is an integer that satisfies the relational expression of 6≦l≦20. ] [Function] The diacetylene derivative compound (hereinafter abbreviated as DA compound) used in the present invention has both a hydrophilic site and a hydrophobic site, and has a 1.4- It is a compound capable of addition polymerization reaction, and typically has the following general formula H( _CH2 )m-C≡C-C≡C-( _CH2 )n-X (wherein, X is a hydrophilic moiety (where m and n represent integers). The hydrophilic group X in the above DA compound is
For example, carboxyl group, amino group, hydroxy group, nitrile group, thioalcohol group, imino group,
Examples include sulfonic acid groups, sulfinyl groups, and metal or amine salts thereof. The alkyl group represented by H(CH ₂ )m forming the hydrophobic site is preferably a long-chain alkyl group having 10 to 30 carbon atoms. Furthermore, m+n is preferably an integer of 1 to 30. On the other hand, the compound having the skeleton represented by the general formula (1) (hereinafter referred to as AZ compound) used in the present invention has an absorption spectrum peak in a wavelength range of 750 nm or more, and is sensitive to infrared light of this wavelength. It is a compound that generates heat. The AZ compounds can be roughly classified into the following three types. In the above formulas (2) to (4), A represents a divalent organic residue bonded via a double bond, for example, and derivatives thereof. Z represents an anionic residue, such as perchlorate, fluoroborate, p-toluenesulfonate, periodide, chloride, bromide or iodide. l is an integer that satisfies the relational expression 6≦l≦20. In addition, the hydrogen atom of the condensed ring of the compound represented by general formulas (2) to (4) may be substituted with a substituent, and examples of the substituent include a halogen atom or a monovalent organic residue. I can do it. Monovalent organic residues can be selected from a wide variety, but especially alkyl groups (methyl,
ethyl, n-propyl, isopropyl, n-butyl, etc.), alkoxy groups (methoxy, ethoxy, etc.), substituted or unsubstituted aryl groups (phenyl, tolyl, xylyl, etc.), substituted or unsubstituted amino groups (amino, dimethylamino), ), nitro group, hydroxy group, cyano group, etc. Examples of the compounds represented by the above general formulas (2) to (4) are shown below. A typical configuration of the optical recording medium of the present invention is illustrated in FIG. FIG. 1 shows a recording layer 2 formed on a substrate 1 by alternately laminating (accumulating) layers A consisting of a monomolecular film of the DA compound 3 and layers B consisting of a monolayer of the AZ compound 4. It is. Note that a protective layer (not shown) may be provided on the recording layer 2 if necessary. As the substrate 1 of the optical recording medium of the present invention, various supporting materials such as glass, a plastic plate such as acrylic resin, a plastic film such as polyester, paper, and metal can be used. When performing recording, a material that transmits recording radiation of a specific wavelength is used. To form the recording layer 2 made of such a monomolecular film or a monomolecular cumulative film on the substrate 1, for example, the Langmiur-Blodget method (hereinafter abbreviated as the LB method) developed by I. Langmiur et al. is used. The LB method is a molecule with a structure that has a hydrophilic group and a hydrophobic group within the molecule, and when the balance between the two (amphiphilic balance) is maintained appropriately, the molecule faces the hydrophilic group downward on the water surface. This is a method of creating a monomolecular film or a film made of accumulated monomolecular layers by utilizing the fact that the monomolecular layer forms a monomolecular layer. 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, ΠΑ=kT, holds between the area A per molecule and the surface pressure Π, resulting in a "gas film." Here, k is Boltzmann's constant and T is absolute temperature. If A is made sufficiently small, the intermolecular interaction will become stronger, resulting in a two-dimensional solid "condensed film (or solid film)". The condensed film can be transferred layer by layer to the surface of a substrate such as glass. Using this method, a monomolecular film of a DA compound or a cumulative film thereof constituting the recording layer according to the present invention is formed.
A monomolecular film of AZ compound salt or a hetero film with a cumulative film thereof is produced, for example, as follows. First, on one side of the liquid surface where the two types of monomolecular films spread on the liquid surface do not mix with each other, a DA compound previously dissolved in a solvent such as chlorofilm is spread on the liquid surface, and this compound is formed into a film. A developed layer is formed. Next, to prevent this spread layer from spreading freely on the water phase and spreading too much, a partition plate (or float) is provided to limit the area of the spread layer and control the aggregation state of these compounds. Proportional surface pressure Π
get. By moving this partition plate, the developed area can be reduced to control the state of aggregation of the film material, and the surface pressure can be gradually increased to set a surface pressure Π suitable for producing a cumulative film. By gently raising and lowering a clean substrate vertically while maintaining this surface pressure,
A monolayer of DA compound is transferred onto the substrate. Next, this substrate was moved onto the surface of the liquid on which the AZ compound had been developed by dissolving the AZ compound in a solvent such as chloroform, and the same operation as above was performed.
Transfer a monolayer of AZ compound onto a substrate. By repeating the above operations, a hetero film with a desired degree of accumulation is formed. Note that, depending on the case, the AZ compound may be formed into a film on the substrate first. In addition to the above-mentioned vertical dipping method, methods such as a horizontal deposition method and a rotating cylinder method can be used to transfer the monomolecular film onto a substrate. The horizontal deposition method is a method in which the substrate is brought into horizontal contact with the water surface and transferred, and the rotating cylinder method is a method in which a cylindrical substrate is rotated on the water surface to transfer a monomolecular layer onto the surface of the substrate. In the vertical immersion method described above, when a substrate with a hydrophilic surface is lifted out of water in a direction transverse to the water surface, a monomolecular layer is formed on the substrate with the hydrophilic groups of the DA compound or AZ compound facing the substrate as the first layer. be done. As the substrate is moved up and down, one layer of monolayer is deposited with each step. Since the direction of the film-forming molecules is reversed between the pulling process and the dipping process, according to this method, a Y-shaped film is formed in which hydrophilic groups and hydrophilic groups and hydrophobic groups face each other between each layer. On the other hand, the horizontal deposition method is a method in which the substrate is brought into horizontal contact with the water surface and transferred, and a monomolecular layer of the DA compound with the hydrophobic group facing the substrate is formed on the substrate. In this method, there is no change in the orientation of the DA compound molecules even if they are accumulated, and an X-type film is formed in which the hydrophobic groups face the substrate in all layers. On the other hand, a cumulative film in which the hydrophilic groups in all layers face the substrate side is called a Z-type film. The rotating cylinder method is a method in which a cylindrical substrate is rotated on the water surface to transfer a monomolecular layer onto the surface of the substrate.
The method of transferring a monomolecular layer onto a substrate is not limited to these methods, but when using a large-area substrate,
A method of extruding the substrate from a substrate roll into an aqueous phase may also be used. Furthermore, the directions of the aforementioned hydrophilic groups and hydrophobic groups toward the substrate are in principle, and can be changed by surface treatment of the substrate. The details of these monomolecular film transfer operations are already publicly known, for example, "New Experimental Chemistry Course 18
"Interfaces and Colloids", pp. 498-507, published by Maruzen. Normally, when creating a monolayer, the methods for creating a monolayer (LB film) of molecules with unbalanced amphiphilic properties are to sandwich the molecules between molecules with balanced amphiphilic properties, Alternatively, a method can be considered in which a hydrophilic site or a hydrophobic site is introduced so that the above molecule has a balanced amphipathic property, and the LB film is formed using the above molecule alone. The monomolecular film of the AZ compound used in the present invention was formed by adopting the latter method, and the present inventors have discovered through research that this method is particularly superior from the viewpoint of film formability. It was. The mixing ratio of the DA compound and the AZ compound is preferably 20/1 to 1/20, preferably 10/1 to 1/10. In addition, the total thickness of the layer consisting of the DA compound and the layer consisting of the AZ compound is 100 Å to 2 μ.
is preferable, and more preferably 200 Å to 5000 Å. In this way, the hetero-cumulative layer formed on the substrate has a high density and a high degree of order, so variations in light absorption depending on location are extremely small. In addition, since the AZ compound itself has film-forming properties,
The formed hetero-cumulative film has particularly excellent film formability, and peeling or flaking of the film hardly occurs during the cumulating process. Furthermore, since the density of the AZ compound was substantially increased, it became possible to record with higher sensitivity. Therefore, by configuring the recording layer with such a film, high density, high resolution, high precision, and high density optical recording and thermal recording are possible depending on the functions of the DA compound and the AZ compound salt. A recording medium having a highly sensitive recording function can be obtained. The optical recording medium of the present invention allows various types of optical recording to be performed; however, by applying light or heat, the absorption wavelength of the recording layer changes and the apparent color changes. The recording mechanism using a semiconductor laser will be briefly explained below. Initially, DA compounds are almost colorless and transparent, but upon irradiation with ultraviolet light, they polymerize and transform into polydiacetylene derivative compounds. This polymerization occurs only by irradiation with ultraviolet light and not by the application of other physical energy such as heat. As a result of this polymerization, the recording layer has a maximum absorption wavelength in the range of 620 to 660 nm and turns blue. This change in hue due to polymerization is an irreversible change, and once the recording layer changes to blue, it does not return to a colorless transparent film. In addition, when this polydiacetylene derivative compound that has changed to blue color is heated to about 50℃ or higher, it turns to about 540N.
It has a maximum absorption wavelength at m, and turns into a red film. This change is also an irreversible reaction. Therefore, optical recording using the recording medium of the present invention is performed by the following mechanism. First, when the entire recording layer of the recording medium of the present invention is irradiated with ultraviolet rays, the DA compound 3 in the recording layer polymerizes and changes into a polydiacetylene derivative compound, thereby changing the recording layer 2 into a blue film. Next, as shown in FIG. 3, a light beam with a wavelength of 800 to 850 nm that blinks in response to the information signal is placed at a predetermined position on this recording medium.
When the polydiacetylene derivative compound is irradiated with a semiconductor laser beam 6 of
However, the AZ compound salt 4 in the recording layer absorbs this laser beam 6 and generates heat. This AZ
The heat generated by compound salt 4 is transmitted to the adjacent polydiacetylene derivative compound, and the color changes to red. In this way, optical recording is performed by changing the color of the recording region 5 on the recording layer in accordance with the input information. [Examples] Hereinafter, the present invention will be explained in more detail based on Examples. Examples 1 to 5 The apparatus shown in FIG. 4 was used to form a monomolecular film. A solution in which 1 part by weight of the AZ compound No. 5 was dissolved in chloroform at a concentration of 5 x 10 ^-3 mol/was developed on the aqueous phase 10. After removing the solvent chloroform, while keeping the surface pressure constant, the glass substrate 1, which has been thoroughly washed and has a hydrophilic surface, is gently moved in a direction across the water surface at a vertical speed of 1.0 cm/min. Move it up and down,
A monomolecular film of an AZ compound or a cumulative film thereof was transferred onto a substrate. Next, C ₁₂ H ₂₅ was added onto an aqueous phase with a pH of 6.5 and a cadmium chloride concentration of 1×10 ⁻³ mol/separate from the aqueous phase.
A solution prepared by dissolving 1 part by weight of a diacetylene derivative compound represented by -C≡C- _C≡C - _C8H16 -COOH in chloroform at a concentration of 1×10 ^-3 mol/was developed. By the same method as described above, a monomolecular film of a DA compound or a cumulative film thereof was transferred onto a substrate having a monomolecular film of an AZ compound or a cumulative film thereof. By repeating this operation, optical recording media shown in Table 1 were created. The meanings of symbols etc. shown in the media configuration are as follows. G/10*(DA/AZ) Monomolecular film of AZ compound and AZ on glass substrate (G)
A structure in which a monomolecular film of a compound is alternately stacked (accumulated) 10 times. G/30DA/20AZ/30DA 20 monolayers of DA compound on a glass substrate
The structure consists of laminating layers, then laminating 20 layers of a monomolecular film of an AZ compound, and then laminating 30 layers of a DA compound. Comparative Examples 1-2 In Examples 1-2, except that 2 parts by weight of arachidic acid and 1 part by weight of the compound represented by the following formula were used instead of 1 part by weight of compound No. 5. An optical recording medium was prepared in the same manner as in Example 1. Examples 6 to 10 In Examples 1 to 5, C ₁₂ H ₂₅ −C≡C−C
C ₈ H ₁₇ −C≡ instead of ≡C−C ₈ H ₁₆ −COOH
Except for using C-C≡C-C ₂ H ₄ -COOH and using compound No. 16 instead of compound No. 5,
Optical recording media were produced in the same manner as in Examples 1 to 5. It is shown in Table-2. Comparative Examples 3-4 In Examples 6-7, instead of using compound No. 16, 2 parts by weight of arachidic acid (hereinafter referred to as AR compound) and a compound represented by the following formula (hereinafter referred to as AR compound) were used.
Optical recording media were prepared in the same manner as in Examples 5 and 6, except that 1 part by weight (referred to as AZ ^* compound) was used. It is shown in Table-2. Recording Test The optical recording media prepared in Examples 1 to 10 and Comparative Examples 1 to 4 were uniformly and sufficiently irradiated with 254 nm ultraviolet rays to turn the recording layer into a blue film. Next, the output is 2mW,
A semiconductor laser beam with a wavelength of 830 nm and a beam diameter of 1 μm is irradiated at a predetermined position on the surface of each optical recording medium according to the input information (irradiation time 200 ns/1 bit),
A red recorded image was formed on the blue recording layer. The evaluation of this recording result is shown in Table 3. The evaluation was based on the quality of the image resolution, with a particularly good image being rated ◎, a good image being rated ◯, and an image that could not be recorded or was defective being rated ×. Furthermore, the recording sensitivity was evaluated based on the minimum irradiation time required to make a readable color change record when the irradiation time of the laser beam was changed with the same output. For reading, visible light of 500 to 750 nm was irradiated and the reflected light was detected. In addition, film forming properties were evaluated in terms of film forming rate and film surface unevenness. The film formation rate was determined by performing the operation of accumulating a monomolecular film on 20 mmφ circular glass substrates on 50 glass substrates, and calculating the rate at which the monomolecular film peeled off or peeled off during the accumulation process out of the 50 operations. was based on the percentage of times the film was successfully transferred onto the substrate. 50% or less
Observe the film surface condition under a magnification of 500 times). If the film surface is uniform, mark it as ○. If there is partial peeling, mark it as △.
A sample with peeling over a wide area and marked unevenness on the surface was rated as "×".

【table】

【table】

【table】

[Table] [Effects of the Invention] The effects of the recording medium of the present invention are listed below. (1) Since the recording layer is formed of a hetero monomolecular film of DA compound and AZ compound salt or a cumulative film thereof, it has a high density and a high degree of order. Therefore, high density and homogeneous recording is possible. It is possible. (2) It is possible to produce a highly homogeneous recording layer at low cost even on a large-area support. (3) Since the recording layer contains an AZ compound salt that absorbs infrared rays in the wavelength range of 800 to 850 nm and generates heat,
Recording can be performed using a small and lightweight semiconductor laser that emits infrared radiation in the wavelength range of 800 to 850 nm. (4) Since it is possible to record using changes in the hue of the recording layer due to light irradiation, high-speed, high-density optical recording can be performed. (5) Since both the DA compound and the AZ compound have excellent film-forming properties, the recording layer composed of these compounds will not peel or peel off, resulting in extremely high recording reliability. (6) Since a single LB film of AZ compound can be created, AZ
Since the density of the compound is substantially increased and the AZ compound and the DA compound can be accumulated alternately one layer at a time, recording with very high sensitivity and high resolution is possible.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional views illustrating the structure of the optical recording medium of the present invention, FIG. 3 is a diagram showing the optical recording process according to the present invention, and FIG.
Figures a and b are schematic diagrams showing an example of a film forming apparatus used in the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Recording layer, 3... Monomolecular film of DA compound, 4... Monomolecular film of AZ compound, 5...
... Recording site, 6... Laser beam.

Claims (1)

[Scope of Claims] 1. A monomolecular film of a diacetylene derivative compound or a cumulative film thereof (film A), and a monomolecular film of a compound having a skeleton represented by the following general formula (1) or a cumulative film thereof (film B) An optical recording medium characterized in that the A film and the B film are laminated and have two or more bonding surfaces between the A film and the B film. [However, in the formula, l is an integer that satisfies the relational expression of 6≦l≦20. ]