JPS62151387A - Optical recording medium - Google Patents

Abstract

PURPOSE:To provide an optical recording medium capable of performing high- density and high-sensitivity recording at a high speed using semiconductor laser, by providing a layer having a monomolecular film mixture consisting of a diacetylene derivative compound having both of a hydrophilic area and a hydrophobic area and one or more of a compound represented by a specific formula or a built-up film thereof. CONSTITUTION:A diacetylene derivative compound (DA compound) having both of a hydrophilic area and a hydrophobic area is represented by formula H(CH2)m-CidenticalC-CidenticalC-(CH2)n-X [wherein X is a hydrophilic group and H(CH2)m- is a hydrophobic group]. A polymethylene compound represented by formula 1 or 2 has an absorption peak in a wavelength region of 750nm or more and generates heat with infrared rays having said wavelength. In order to form a recording layer composed of a monomolecular film mixture of the DA compound and the polymethylene compound on a substrate, for example, a Langmuir-Blodgett's method is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium, and particularly to an optical recording medium suitable for optical writing using an infrared laser.

[Conventional technology]

Recently, optical discs have been attracting attention as a central player in office automation. Optical discs can store large amounts of documents, literature, etc. on a single disc, so
Ability to organize and manage documents, etc. in the office efficiently. 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. Focusing on the thermochromic properties of these compounds, a recording technique for use in laser recording elements was disclosed in Japanese Patent Laid-Open No. 56-147807. There is. 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 It was confirmed that laser recording could not be performed when a low-output semiconductor laser (wavelength: 800 to 850 nm) was used. However, for practical recording media such as optical discs, it is required that optical writing be possible using a small, low-output semiconductor laser.

On the other hand, JP-A-59-40648, JP-A-59-40649 and JP-A-JP-A-40650 disclose organic coatings containing a polymethylene compound having a specific structure with good thermal stability. It is disclosed that since radiation is absorbed and heat is generated, so-called heat mode recording in which pits are formed using laser energy can be performed in practice. However, when recording is performed by forming physical pits on the surface of a recording medium, the surface of the initial recording layer must be sufficiently smooth and at the same time the surface of the recording medium will not be damaged even after recording. In addition, it is relatively difficult to perform high-density, high-speed recording.

Furthermore, the recording layer of these recording media is composed of microcrystals of a diacetylene derivative compound or the polymethylene compound dispersed in a binder, and the orientation of these compounds within the recording layer is random, so that the orientation of these compounds varies depending on the location. Phenomena such as differences in light absorption and reflectance, and differences in the degree of chemical reactions occurred, making them not necessarily suitable for high-density recording.

[Problem that the invention seeks to solve]

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.

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.

[Means for solving problems]

That is, the optical recording medium of the present invention comprises a mixed monomolecular film of a diacetylene derivative compound having at least a hydrophilic site and a hydrophobic site, and one or more compounds represented by the following general formula (+) or (2). or a recording layer having a cumulative film thereof.

General formula (1) General formula (2) (in the formula, R1, R2, and R3 each independently represent an aryl group that may have a substituent, and R4 and R5 represent adjacent two groups) represents an arylene group that may have a substituent that forms a conjugated double bond system with two -GIl=GH- groups, R6 represents hydrogen or an aryl group that may have a substituent, and A is an anion. ) The diacetylene derivative compound (hereinafter abbreviated as DA compound) having both a hydrophilic site and a hydrophobic site used in the present invention is defined as c=c-c=c-c in adjacent molecules. It is a compound capable of 1.4-addition polymerization reaction between functional groups, and is typically represented by the following general formula 8% (wherein, X is a hydrophilic group forming a hydrophilic site,
m and n represent integers. ) Compounds represented by:

Examples of the hydrophilic group X in the above DA compound include a carboxyl group, an amino group, a hydroxy group, a nitrile group,
Examples include 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(Gf12)i- forming the hydrophobic site is preferably a long-chain alkyl group having 1 to 30 carbon atoms. Further, n+m is preferably an integer of 10 to 30.

On the other hand, the general formula (+, ) or (2
) (hereinafter abbreviated as polymethylene compound) is a compound that has an absorption peak in a wavelength range of 750 nm or more and generates heat by infrared light of this wavelength.

To explain this polymethylene compound salt more specifically, in general formulas (+) and (2), R1, R2 and R
3 each independently represents an aryl group such as a phenyl group or a naphthyl group which may have a substituent.

Examples of substituents include substituted amino groups such as dimethylamino, diethylamino, dipropylamino, dibutylamino, diphenylamino, phenylbenzylamino, and phenylethylamino, cyclic amino groups such as morpholino, piperidinyl, and pyrrolidino, methoxy, ethoxy, and butoxy. Examples include alkoxy groups such as. R4 and R5 are two adjacent -G groups such as P-phenylene and 1,4-naphthylene.
H= represents an arylene group which may have a substituent that forms a conjugated double bond system with the ell- group. Examples of the substituent include halogen atoms such as chlorine, bromine, and iodine, alkyl groups such as methyl and ethyl, and alkoxy groups such as methoxy and ethoxy. R6 represents hydrogen or an aryl group such as a phenyl group or a naphthyl group which may have a substituent.

Examples of the substituent include the same substituents as those exemplified for R1 to R3. For example, BF?
,clF? ,, cF3clla1. −1 hunting i, P, etc.

2. Galley atom, yeah. 3. Sei 13. . 3,eee
e eC2H5S03. C3H
,S03. C4H9SO3,C5H,,503,C,H
, 3So3, θ lCH2503, etc., (D
←c H2s R5cr%cn2sF? , rt tonohensesensur*nM compound! o3scH2sop,”
03SCH7co2s Nada scolding (CH2) 6s2,”03
SC) I2(:R2-0-CH2CH7So!?, etc.) Specific examples of this polymethylene compound are illustrated below.

At 0
Q surprise ◇ surprise 8 -＋
8th grade Kan CJ (J tsur 〆1 6 pieces 5 +
e − (pu εyu
ε8e Q
−δ g3g
3 2 5
89 Sa
0 6Q
66-
13 Kyogusu-j A typical configuration of the optical recording medium of the present invention is illustrated in FIGS. 1 and 2. In the example shown in FIG. 1, a recording layer 2 is formed of a mixed monomolecular film of the OA compound 3 and the polymethylene compound 4 on a substrate 1.
Figure 2 shows a mixed monomolecular cumulative film of these. 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.

In order to form the recording layer 2 made of such a monomolecular film or a phosphor molecule cumulative film on the substrate 1, for example,
The Langmuir-Prodgett method (hereinafter abbreviated as LB method) developed by Uir et al. is used.

In the LB method, when a molecule has a parent wood group and a hydrophobic group in its molecule, and the balance between the two (amphipathic balance) is maintained appropriately, this molecule lowers the parent wood group on the water surface. This is a method of creating a monomolecular film or a film made up of monomolecular layers by taking advantage of the fact that the monomolecular layer becomes a layer directed toward the molecule. 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 nA=kT holds true between the area per molecule A and the surface pressure ■, 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.

In addition, a so-called mixed monomolecular film or mixed monomolecular cumulative film composed of two or more compounds can also be obtained by the same method as described above. At this time, it is sufficient that at least one of the two or more compounds constituting the mixed monomolecular film or the mixed monomolecular cumulative film has both a hydrophilic site and a hydrophobic site,
Not all compounds are necessarily required to have both a hydrophilic site and a hydrophobic group in a hydrophobic portion. In other words, if the amphipathic balance of at least one compound is maintained, a monomolecular layer will be formed on the water surface, and the other compounds will be sandwiched between the amphipathic compounds, resulting in a well-ordered molecular layer as a whole. A monolayer is formed.

Using this method, a mixed monomolecular film or a mixed monomolecular cumulative film of a DA compound and a polymethylene compound constituting the recording layer of the present invention is produced, for example, as follows. First, a DA compound and a polymethylene compound are 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 into a film. Next, a partition plate (
(or a float) is provided to limit the area of the developed layer to control the state of aggregation of these compounds, and to obtain a surface pressure (2) proportional to the state of aggregation. By moving this partition plate, the developed area is reduced to control the aggregation state of the membrane material, and the surface pressure is gradually increased.
It is possible to set a surface pressure (2) suitable for producing a cumulative film. By gently moving the clean substrate vertically up and down while maintaining this surface pressure, a mixed monomolecular film of a DA compound and a polymethylene compound is transferred onto the substrate. A mixed monomolecular layer film is produced in this manner, and a mixed monomolecular layer cumulative film having a desired degree of accumulation is formed by repeating the above 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 described above, when a substrate with a hydrophilic surface is lifted out of water in a direction transverse to the water surface, an m molecular layer is formed on the substrate in which the parent group of the OA compound faces the substrate in the first layer. .

As the substrate is moved up and down, one layer of mixed monomolecular film 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 between each layer in which a hydrophilic group and a parent group, and a hydrophobic group and a hydrophobic group face each other.

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 all the layers have parent groups facing the substrate 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 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 orientation of the aforementioned parent wood group and hydrophobic group toward the substrate is a general rule, and can be changed by surface treatment of the substrate, etc.

Details of these monomolecular film transfer operations are already known and are described, for example, in "New Experimental Chemistry Course 18 Interfaces and Colloids", pages 498-507, published by Maruzen.

In this way, the mixed monomolecular film and its cumulative film formed on the substrate have a high density and a high degree of order, so variations in light absorption depending on location are extremely small. Therefore, by configuring the recording layer with such a film, a recording medium having a high-density, high-resolution recording function capable of optical recording and thermal recording can be created depending on the functions of the D compound and the polymethylene compound. can get.

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.

The DA compound is initially almost colorless and transparent, but when the recording layer is irradiated with ultraviolet rays, it polymerizes and changes into a polyacetylene derivative compound. This polymerization occurs by irradiation with ultraviolet rays, etc., and cannot be caused by simply applying thermal energy. As a result of this polymerization, the recording layer is 620 to 660111+
It has a maximum absorption wavelength at , and the color changes from blue to dark. This change in hue due to polymerization is an irreversible change, and once the recording layer changes from blue to dark, it does not return to a colorless transparent film. Furthermore, when this polyacetylene derivative compound that has changed color from blue to dark is heated to about 50° C. or higher, it now has a maximum absorption wavelength of about 540 nm and changes to a red film. This change is also an irreversible change.

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 2 in the recording layer polymerizes and changes into a polyacetylene derivative compound, thereby changing the recording layer into a blue to dark-colored film. Next, when a predetermined position of this recording medium is irradiated with a semiconductor laser beam with a wavelength of 800 to 850 nm that blinks in response to an information signal, the polyacetylene derivative compound does not absorb this laser beam, but the polymethylene compound 3 in the recording layer absorbs this laser beam. Absorbs laser beams and generates heat. The heat generated by the polymethylene compound 3 is transmitted to the adjacent polyacetylene derivative compound, and the color changes to red. In this way, optical recording is performed by changing the color of the recording area on the recording layer in accordance with the input information.

〔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 mixed monomolecular film of a DA compound and a polymethylene compound or a cumulative film thereof, it has a high density and a high degree of order, thus enabling high density and homogeneous recording. be.

(2) A highly homogeneous recording layer can be manufactured at low cost even on a large-area support.

(3) Since the recording layer contains a polymethylene compound that absorbs infrared rays in the wavelength range of 800 to 850 nm and generates heat, recording is performed using a small and lightweight semiconductor laser that emits infrared rays in the wavelength range of 800 to 850 r++n. can.

(4) Since it is possible to record using changes in the hue of the recording layer due to light irradiation, high-speed, high-sensitivity, and high-density optical recording can be performed.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples.

Example 1 General formula c, 2H75-C=C-C=C-CBH, 6-C
1 part by weight of a diacetylene derivative compound represented by 0OH and 1 part by weight of a polymethylene compound represented by the above compound AIIL5 were mixed in chloroform at 1 x 10-3 mol/
The solution dissolved at a concentration of 1 was developed on an aqueous phase with a pH of 6.5 and a cadmium chloride concentration of txio=mol/1.

After removing the solvent chloroform, while keeping the surface pressure constant, the glass substrate, which has been thoroughly washed and has a hydrophilic surface, was gently moved up and down in the direction across the water surface at a vertical speed of 1.0 cm/min. , an optical recording medium in which a mixed monomolecular film of a DA compound and a polymethylene compound is transferred onto a substrate, and a mixed monomolecular film and a mixed monomolecular cumulative film of 21 layers, 41 layers, and 81 layers are formed on the substrate. It was created.

Example 2 An optical recording medium was produced in the same manner as in Example 1, except that the diacetylene derivative compound was used in an amount of 2 parts by weight per 1 part by weight of the polymethylene compound.

Example 3 An optical recording medium was prepared in the same manner as in Example 1, except that the diacetylene derivative compound was used in an amount of 10 parts by weight per 1 part by weight of the polymethylene compound.

Example 4 An optical recording medium was prepared in the same manner as in Example 1, except that the diacetylene derivative compound was used in an amount of 15 parts by weight per 1 part by weight of the polymethylene compound.

Comparative Example 1 An optical recording medium was produced in the same manner as in Example 1, except that only a diacetylene derivative compound was used without using a polymethylene compound.

Comparative Example 2 A film with a thickness of 1500 mm was formed on a glass substrate by sputtering.
A radiation absorbing layer of human Gd-Tb1'e was provided. Using this substrate, an optical recording medium was prepared in which a monomolecular film or a monomolecular cumulative film of a diacetylene derivative compound was formed on the radiation absorbing layer in the same manner as in Comparative Example 1.

Recording Test 1 The optical recording media prepared in Examples 1 to 4 and Comparative Example 1.2 were uniformly and sufficiently irradiated with 254 nm ultraviolet rays to turn the recording layer into a blue film. Next, a semiconductor laser beam with an output of 3 mW, a wavelength of 830 nm, and a beam diameter of l- is irradiated to a predetermined position on the surface of each optical recording medium according to the input information (irradiation time is 20
0 ns/1 bit), and a red recorded image was formed on the blue recording layer.

The evaluation of the recording results is shown in Table 1. Evaluation is based on recording sensitivity, image resolution, and image density.
Particularly good results were marked as ◎, and those that were good and those that were unable to perform O1 recording or poor were marked as ×.

Table 1 Comparative Example 3 A solution prepared by dissolving 3 parts by weight of a polymethylene compound and 1 part by weight of nitrocellulose in 210 parts by weight of methidium chloride was used as a coating liquid without using a diacetylene derivative compound,
An optical recording medium with a recording layer thickness of 2,000 layers was prepared in the same manner as in Example 1.

Recording Test 2 The optical recording medium having the 41-layer mixed monomolecular cumulative film prepared in Example 2 was subjected to the same procedure as Recording Test 1 except that the irradiation time of the semiconductor laser beam was varied (irradiation time 100 to 800 ns/bit). Recording was performed using the same procedure. Also,
Regarding the optical recording medium of Comparative Example 3, the semiconductor laser beam was directly applied according to the input information without performing ultraviolet irradiation.
Recording was performed by irradiating Q4 (irradiation time 500 ns/bit to 5 μS/bit) on the surface of the recording layer at a predetermined position on the recording medium surface with the same output and varying the irradiation time to form bits.

For the optical recording medium of Example 2, the irradiation time was 200n.
Particularly good recording was achieved when the optical recording medium produced in Comparative Example 2 was observed under a microscope and found that an irradiation time of 2.5 μs or more was required to clearly form one bit. It turned out that it required.

Example 5 General formula C,2,H2s-CE to -C3C-C3H16
Instead of the diacetylene derivative compound represented by -C0OH, the general formula C3H17-CEC-(jC-C,H4-C
An optical recording medium was prepared in the same manner as in Example 2 except that a diacetylene derivative compound represented by 0OH was used.

Examples 6 to 9 Instead of the polymethylene compound represented by compound A14,
Optical recording media were prepared in the same manner as in Example 5, except that polymethylene compounds represented by compounds Al1LI, 5.18, and 26 were used, respectively.

Recording Test 3 Using the optical recording media prepared in Examples 5 to 9, a recording test was conducted in the same manner as Recording Test 1. The evaluation of this recording result is shown in Table 2.

Table 2

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic cross-sectional views illustrating the structure of the optical recording medium of the present invention. 1: Substrate 2 Diacetylene derivative compound 3: Polymethylene compound

Claims (1)

[Scope of Claims] 1) A mixed monomolecular film of a diacetylene derivative compound having at least a hydrophilic site and a hydrophobic site and one or more compounds represented by the following general formula (1) or (2), or a mixed monomolecular film thereof. An optical recording medium characterized by having a recording layer having a cumulative film. General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) General formula (2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) (In the formula, R^1, R^2, R^ 3 represents an aryl group that may each independently have a substituent, and R^4 and R^5 are substituents that form a conjugated double bond system with two adjacent -CH=CH- groups. represents an arylene group which may have a substituent, R^6 represents hydrogen or an aryl group which may have a substituent, and A represents an anion residue.)