JPH0475837B2 - - 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-power laser such as an argon laser, it is possible to record thermochromic changes using a small and relatively low-power laser. Output 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-56-14708 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 provides an optical recording medium characterized by having a monomolecular film of a diacetylene derivative compound or a cumulative film thereof, and a monomolecular film of a compound having a skeleton represented by the following general formula (1) or a cumulative film thereof. It is. [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-addition in the C≡C-C≡C functional period. It is a compound capable of polymerization reaction, and typically has the following general formula H(CH ₂ )m-C≡C-C≡C-(CH ₂ )n-X (wherein, X represents a hydrophilic moiety). It is a hydrophilic group to form, m and n represent integers). The hydrophilic group X in the above DA compound is
For example, carboxy group, amino group, hydroxy group,
Examples include a nitrile group, a thioalcohol group, an imino group, a sulfonic acid group, a sulfinyl group, or a metal or amine salt 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 10 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 engaged through a double bond, for example, and derivatives thereof. Z represents an anionic residue, such as perchlorate, fluoroborate, p-toluenesulfonate, periodide, chloride,
Bromide or iodide, etc. 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 the substituent may be a halogen atom or a monovalent organic residue. can be mentioned. 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. In this example, a B layer 4 made of a monomolecular film of the AZ compound or a cumulative film thereof is formed on the substrate 1, and an A layer 3 made of a monomolecular film of the DA compound or a cumulative film thereof is laminated thereon, These two layers constitute the recording layer 2. A layer 3 and B
The stacking order with layer 4 is not limited to the embodiments shown in these figures, but may be stacked in the reverse order,
It is preferable to stack the recording layer 2 so that the A layer 3 consisting of a monomolecular film of a DA compound or a cumulative film thereof appears on the surface side of the recording layer 2. Furthermore, other layers such as a transparent protective layer may be provided on the recording layer 2, if necessary. The thickness of both A layer 3 and B layer 4 is 100 Å ~
The thickness is preferably 2μ, more preferably 500Å to 5000Å. As the substrate 1 of the optical recording medium of the present invention, various supporting materials such as glass, plastic plates such as acrylic resin, plastic films 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 a monomolecular film of an AZ compound or a cumulative film thereof on the substrate 1, or a monomolecular film or a monomolecular cumulative film of a DA compound on the substrate 1, for example, the Langmiur-Blodget method (hereinafter referred to as the LB method) developed by I. Langmiur et al. ) is used. In the LB method, in molecules with a structure that has a hydrophilic group and a hydrophobic group in the molecule,
When the balance between the two (balance of amphiphilic properties) is maintained appropriately, this molecule forms a monomolecular layer on the water surface with the hydrophilic groups facing downward, forming a monolayer or monolayer. This is a method of creating a film with a cumulative amount of 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 ΠA=kT holds true between the area per molecule A and the surface thickness 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, for example, a monomolecular film or a monomolecular cumulative film of a DA compound is produced as follows. First, a DA compound is dissolved in a solvent such as chloroform, and this is spread on an aqueous phase to form a spread layer in which these compounds are spread in the form of a film. Next, to prevent this spread layer from spreading freely on the aqueous 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 the DA compound. Obtain proportional surface pressure. By moving this partition plate, the developed area can be reduced to control the aggregation state of the film material, and the surface pressure can be gradually increased to set a surface pressure suitable for producing a cumulative film. By vertically moving a clean substrate or a substrate on which the B layer is formed while maintaining this surface pressure vertically, a monomolecular film of the DA compound is transferred onto the substrate or the B layer. Although a monomolecular film is produced in this way, a monomolecular cumulative film having a desired degree of accumulation is formed by repeating the above-mentioned operations. 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 mentioned 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 first layer of hydrophilic groups of the DA compound facing the substrate. 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 the hydrophilic and hydrophilic groups and the 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 side in all layers. On the contrary, 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 a water surface and a monomolecular layer is transferred onto the surface of the substrate.
The method of transferring the monomolecular layer onto the substrate is not limited to these methods, and 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 hydrophilic groups and hydrophobic groups described above toward the substrate are in principle, and can be changed by surface treatment of the substrate. The details of these monolayer transfer operations are already publicly known, for example, in ``New Experimental Chemistry Course 18''.
"Interfaces and Colloids", pp. 498-507, published by Maruzen. A monomolecular film of an AZ compound or a cumulative film thereof can also be formed by the same method as described above. 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 this way, the cumulative layer of monomolecular film formed on the substrate has a high density and a high degree of order, so that variations in light absorption depending on the location are extremely small. In addition, since the AZ compound itself has film-forming properties,
The formed cumulative film has particularly excellent film formability,
During the accumulation process, there is almost no peeling or peeling of the film. Furthermore, by separating the layer containing the AZ compound and the layer containing the DA compound, the density of the AZ compound molecules was substantially increased, resulting in improved sensitivity to light. 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 can carry out optical recording using various methods. The function of recording using a semiconductor laser will be briefly explained. 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°C or higher, the color changes to about 540nm.
It has a maximum absorption wavelength at , and turns into a red film. This change is also an irreversible change. Therefore, optical recording using the recording medium of the present invention is carried out by the following mechanism, as shown in FIGS. 2a and 2b. First, when the entire recording layer of the optical 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.
When irradiated with a semiconductor laser beam 7 of 800 to 850 nm, the polydiacetylene derivative compound does not absorb this laser beam 7, but the AZ compound salt 4 in the recording layer absorbs this laser beam 7 and generates heat. The heat generating portion 5 of this AZ compound salt 4 is transmitted to the adjacent layer 6 containing the polydiacetylene derivative compound, and the color changes to red. In this way, optical recording is performed by changing the color of the recording region 6 on the recording layer in accordance with the input information. [Examples] Hereinafter, the present invention will be explained in more detail based on Examples. Example 1 The apparatus shown in FIG. 3 was used to form a monomolecular film. One part by weight of the AZ compound No. 5 was dissolved in chloroform at a concentration of 5 x 10 ^-3 mol/, and then spread on the aqueous phase 10. After removing the solvent chloroform by evaporation, the surface pressure was
Increased to 20dyn/cm. Using a glass substrate with a sufficiently clean surface as a carrier while keeping the surface pressure constant,
The AZ compound is transferred onto the carrier 11 by gently moving it up and down in the direction across the water surface at a vertical speed of 1.0 cm/min, and the monomolecular film and the monomolecular cumulative films accumulated in 7 layers, 41 layers, and 101 layers are formed respectively. formed on a substrate. Next, calcium chloride concentration 1× at another pH6.5
On the aqueous phase of 10 ^-3 mol/C ₁₂ H ₂₅ -C≡C-C≡
A solution prepared by dissolving a diacetylene derivative compound represented by C- _C8H16 - _COOH in chloroform at a concentration of 3 x ^10-3 mol/was developed. A monomolecular film of a DA compound, 7 layers, 41 layers,
An optical recording medium of the present invention was produced by forming a monomolecular cumulative film of 101 layers. Example 2 In Example 1, No. 5 AZ compound was replaced with No.
An optical recording medium was prepared in the same manner as in Example 1 except that No. 16 AZ compound was used. Example 3 In Example 1, C ₁₂ H ₂₅ −C≡C−C≡C
-C ₈ H ₁₆ -C ₈ H ₁₇ instead of DA compound of -COOH
An optical recording medium was prepared in exactly the same manner as in Example 1 except that -C≡C-C≡C-C ₂ H ₄ -COOH was used. Example 4 In Example 2, C ₁₂ H ₂₅ −C≡C−C≡C
-C ₈ H ₁₆ -C ₈ H ₁₇ instead of DA compound of -COOH
An optical recording medium was prepared in exactly the same manner as in Example 2 except that -C≡C-C≡C-C ₂ H ₄ -COOH was used. Comparative Example 1 In Example 1, light was applied in the same manner as in Example 1, except that 2 parts by weight of arachidic acid and 1 part by weight of AZ compound represented by the following formula were used in place of AZ compound No. 5. Created a recording medium. Comparative Example 2 The same procedure as in Example 3 was carried out, except that 2 parts by weight of arachidic acid and 1 part by weight of the AZ compound represented by the following formula were used in place of AZ compound No. 5. An optical recording medium was created. Recording Test The optical recording media prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were uniformly and sufficiently irradiated with 254 nm ultraviolet rays to make the recording layer a blue film. Next, the output is 3mW,
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 1. Evaluation was made based on the quality of recording sensitivity, image resolution, and image density. Particularly good results were evaluated as ◎, good results were evaluated as ○, and those that could not be recorded or were poor were evaluated as ×. In addition, film forming properties were evaluated in terms of film forming rate and film surface unevenness. The film formation rate is calculated by performing an operation of accumulating a monomolecular film on a circular glass substrate of 20 mmφ for each cumulative number of times on 50 glass substrates, and peeling off the monomolecular film during the cumulative process of the 50 operations. , based on the percentage of times the film was successfully transferred onto the substrate without peeling. 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 △.
If peeling occurred over a wide range and the surface had sharp irregularities, it was rated as ×.

【table】

〔Effect 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 monomolecular film stack of a DA compound and an AZ salt compound, it has a high density and a high degree of order, making it possible to perform high-density and homogeneous recording. be. (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 rays in the wavelength range of 800 to 850 nm. can be implemented. (4) Since it is possible to perform recording using the change in hue of the recording layer due to light irradiation, high-speed, high-resolution, and high-density optical recording can be performed. (5) Both DA and AZ compounds have excellent film-forming properties, so there is no peeling or peeling of the film during the accumulation process, resulting in excellent productivity and recording on the formed optical recording medium. has very high reliability. (6) Since it substantially improves the density of the AZ compound,
Highly sensitive optical recording is possible.

[Brief explanation of the drawing]

FIG. 1 is an exemplary schematic cross-sectional view showing the optical recording medium of the present invention, FIGS. 2 a and b are diagrams showing a recording process using the optical recording medium of the present invention, and FIGS. 3 a and b
1 is a schematic diagram showing an example of a film forming apparatus used in the present invention. 1: Substrate, 2: Recording layer, 3: DA compound-containing layer, 4: AZ compound-containing layer, 5: Exothermic site, 6:
Recording site, 7: Laser beam.

Claims (1)

[Scope of Claims] 1. A light characterized by having a monomolecular film of a diacetylene derivative compound or a cumulative film thereof and a monomolecular film of a compound having a skeleton represented by the following general formula (1) or a cumulative film thereof. recoding media. [However, in the formula, l is an integer that satisfies the relational expression of 6≦l≦20. ]