JPS62149484A - Optical recording medium - Google Patents

Abstract

PURPOSE:To provide an optical recording medium capable of high-speed recording with high density and high resolution, by providing a recording layer comprising a mixed monomolecular film or built-up film of a diacethylene derivative compound having a hydrophilic part and a hydrophobic part and at least one of two specified compounds. CONSTITUTION:An optical recording medium has a recording layer which comprises a mixed monomolecular film or built-up film of a diacethylene derivative compound having at least at hydrophilic part and a hydrophobic part and at least one of compounds of general formulas (1) and (2), wherein R<1> is an alkyl or substd. or unsubstd. phenyl or styryl, each of R<2> and R<6> is an arylene which may have substituent groups for forming a conjugated double bond system with the two adjacent -CH=CH- groups, each of R<3> and R<7> is a substd. or unsubstd. phenyl or naphthyl, R<1> is an alkoxyl, R<5> is an alkyl and A is an anion residue. With this optical recording medium, uniform recording can be performed with high density, recording can be performed by using a small-type lightweight semiconductor laser, and optical recording can be performed at high speed with high sensitivity and high density.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium (in particular, 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
Organize and manage documents, etc. in the office efficiently. Various types of recording elements are being considered as recording elements 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 by focusing on the thermochromic properties of these compounds, a recording technology for use in laser recording elements was disclosed in JP-A-56-147807. I'm here. However, this specification does not describe what kind of laser was used or should be used, but merely states that recording was performed using a laser.

The inventors? ! As a result of examining laser recording of this diacetylene derivative compound using various lasers, we found that
It was confirmed that although thermochromic recording is possible using a large, high-power laser such as an argon laser, laser recording is not possible when using a small and relatively low-power semiconductor laser (wavelength 800-850 nm). did.

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-59-84248 and JP-A-84249 disclose organic coatings containing a salt of a diene compound having a specific structure with good thermal stability, and these organic coatings are resistant to radiation in the semiconductor laser radiation wavelength range. absorbs and generates heat,
It is disclosed that so-called heat mote recording, in which pits are formed by laser energy, can be carried out. However, when recording is performed by forming physical bits on the surface of a recording medium, the surface of the initial recording layer must be sufficiently smooth and the surface of the recording medium will not be scratched even after recording. However, it is relatively difficult to perform high-density, high-speed recording.

Furthermore, the recording layer of these recording media is made up of microcrystals of diacetylene derivative compounds or salts of the above-mentioned diene compounds dispersed in a binder, and the orientation of these compounds within the recording layer is random. Phenomena occurred in which the absorption and reflectance of light varied depending on the location, and the degree of chemical reaction varied, making it 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 monomer mixture of a diacetylene derivative compound having at least a lignophilic site and a hydrophobic site, and one or more compounds represented by the following general formula (1) or (2). It is characterized by having a recording layer comprising a film or a cumulative film thereof.

General formula (1) General formula (2) (wherein, R1 represents an alkyl group, a phenyl group or a styryl group which may have a substituent, and R2 and Rh are
Represents an arylene group that may have a substituent that forms a military double bond system with two adjacent 10H=CH- groups, and R
:' and R7 represent a phenyl group or a naphthyl group which may have a substituent, R4 represents an alkoxy group, R'= represents an alkyl group, and A represents an anion residue. ) The diacetylene derivative compound (hereinafter abbreviated as OA compound) that has both a lignophilic site and a hydrophobic site used in the present invention is defined as It is a compound capable of 1.4-addition polymerization reaction, and is typically represented by the following general formula 8 (wherein, X is a hydrophilic group forming a hydrophilic part, m and n are integers) ).

Examples of the wood-philic group X in the above OA compound include a carboxyl group, an amine 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(CH2)m 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 1 to 30.

On the other hand, the compound represented by the general formula (1) or (2) used in the present invention (hereinafter abbreviated as diene compound salt)
is a compound that has an absorption peak in a wavelength range of 750 nm or more and generates heat when exposed to infrared light of this wavelength.

To explain this diene compound salt more specifically, in general formulas (1) and (2), R1 is an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, hexyl, or a phenyl group that may have a substituent. Or it represents a styryl group. Here, substituents include methoxy, ethoxy,
Examples include alkoxy groups such as butoxy, halogen atoms such as chlorine, bromine, and iodine, alkyl groups such as methyl, ethyl, brohydryl, and isopropyl, and nitro groups. R2 and R1 (y) represent an arylene group that may have a substituent that forms a conjugated double bond system with two adjacent -CH=CH- groups such as p-phenylene and 1,4-naphthylene. Examples of substituents include halogen atoms such as chlorine, bromine and iodine, alkyl groups such as methyl and ethyl, and alkoxy groups such as methoxy and ethoxy.

R: 4 and R7 represent a phenyl group or a naphthyl group which may have a substituent. Examples of M substituents include substituted amino groups such as dimethylamino, diethylamino, dipropylamino, dibutylamino, diphenylamino, phenylamino, phenylhensylamine, and noenylethylamino;
Examples include cyclic amino groups such as morpholino, piperidinyl, and pyrrolidino, and alkoxy groups such as methoxy, ethoxy, and butoxy. R'' represents an alkoxy group such as methoxy, ethoxy, butoxy, etc. R5 represents an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, hexyl, etc. A is an anionic residue, for example (→
(→ ←)CbHI:4 SO3,
CthCHCISO: < , ClCH2CH25Oa
, CH3 is generated.

Specific examples of this diene compound are illustrated below.

A typical configuration of the optical recording medium of the present invention is shown in FIGS. 1 and 2.
An example is shown in the figure. In the example shown in FIG. 1, a recording layer 2 made of a mixed monomolecular film of the OA compound 3 and the diene compound salt 4 is formed on a substrate 1, and in FIG. It is something that 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, or a fully flexible material may be used, or radiation may be irradiated from the substrate side. When recording is performed using a recording medium, one 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, 1. Langmu
The Langmuir-Prodgett method (hereinafter abbreviated as the La method) developed by ir et al. is used.

In the La 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 at an appropriate level, 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, A=kT, holds between the area per molecule and the surface pressure, resulting in a gas film. , k is Boltzmann's constant, and ■ is the absolute temperature.If A is made small enough, the intermolecular interaction becomes stronger, resulting in a two-dimensional solid "condensed film (or solid film)".A condensed film is formed on a substrate such as glass. It can be transferred layer by layer to the surface.

Also, a so-called mixed monomolecular film or mixed monomolecular cumulative film made of the compound on a plate can be obtained by the same method as described above. At this time, it is sufficient that at least one of the compounds on the plate constituting the mixed monomolecular film or the mixed monomolecular cumulative film has both a hydrophilic site and a hydrophobic site;
It is not necessarily required that all compounds contain both a hydrophilic site and a hydrophobic group. In other words, if the amphipathic balance is maintained in at least one compound, a monomolecular layer will be formed on the water surface, and the other compounds will be sandwiched between the amphipathic compounds, resulting in a molecularly ordered structure as a whole. A certain monolayer is formed.

Using this method, a mixed monomolecular film or a mixed monomolecular cumulative film of an OA compound and a diene compound salt constituting the recording layer of the present invention is produced, for example, as follows. First, OA
A compound and a diene compound salt 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 in the form of a film. Next, to prevent the spread layer from spreading too much on the aqueous phase, a partition plate (or float) is provided to limit the area of the spread layer and control the aggregation state of these compounds. Obtain a proportional surface pressure. By moving this partition plate, the developed area can be reduced to control the aggregation state of the membrane material, gradually increasing the surface pressure, and setting a surface pressure opening through which the cumulative membrane can be produced. By gently moving the clean substrate up and down vertically while maintaining this surface pressure, a mixed monomolecular film of the OA compound and diene compound salt 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-mentioned operations.

In order to transfer the monomolecular film onto the substrate, in addition to the above-mentioned vertical immersion method, methods such as a horizontal deposition method and a rotating cylinder method can be employed. The horizontal deposition method is a method in which the substrate is brought into contact with the water surface horizontally 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 first layer is formed on the parent wood group of the DA compound or a monomolecular layer facing the substrate. .

As the substrate is raised and lowered, one layer of the mixed 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 between each layer in which parent wood groups face each other, and hydrophobic groups face each other.

On the other hand, the horizontal deposition method is a method in which the substrate is brought into contact with the water surface horizontally and transferred, and a monomolecular layer of the hydrophobic group of the OA compound 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 are directed toward the substrate in all layers. On the other hand, a cumulative film in which all layers face either the parent wood base or the substrate side is called an X-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 degree of uniformity and order, so variations in light absorption due to location are extremely small. Once upon a time, by configuring the recording layer with such a film, it was possible to create a recording medium with high-density, high-resolution recording functions capable of optical recording and thermal recording, depending on the functions of the OA compound and diene compound salt. 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, or 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 has a maximum absorption wavelength in the range of 620 to 660 nm, and its color changes from blue to dark.

The change in hue due to this 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 carried out 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 4 in the recording layer polymerizes and changes into a polyacetylene derivative compound, thereby changing the recording layer 2 into a blue film. Next, as shown in FIG.
When irradiated with a semiconductor laser beam 6 of 0 to 850 nm, the polyacetylene derivative compound is exposed to this laser beam 6.
The diene compound salt 4 in the recording layer absorbs this laser beam and generates heat. The heat generated by this diene compound 1 to 4 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 region 5 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 an OA compound and a diene compound salt or a cumulative film thereof, it has a high density and a high degree of order, and therefore can achieve high density and homogeneous recording. 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 a diene 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 00 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-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+, H7b- [:= C-C3C-CoH+6
-1 part by weight of the diacetylene derivative compound represented by GO Kano and the diene compound 11 represented by the above compound No. 1
Parts by weight were dissolved in chloroform at a concentration of 1X10-' mol/l and developed on an aqueous phase having a pH of 6.5 and a concentration of cadmium chloride of 1X10-' mol/It. After removing the solvent chloroform, while keeping the surface pressure constant, the glass substrate, which has been thoroughly washed and whose surface has become hydrophilic, was gently moved up and down in the direction across the water surface at a vertical speed of 1.0 cm/min. , a mixed monomolecular film of a DA compound and a diene compound salt was transferred onto a substrate, and the mixed monomolecular film and 21
Optical recording media were prepared in which mixed monomolecular cumulative films of 41 layers and 81 layers were formed on a substrate.

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

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 diene compound salt.

Example 4 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 15 parts by weight per 1 part by weight of the diene compound salt.

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 diene compound salt.

Comparative Example 2 A film with a thickness of 1500 mm was formed on a glass substrate by sputtering.
A radiation absorption layer made of human Gd/Tb-Fe 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 Examples 1.2. were uniformly and sufficiently irradiated with 254 nm ultraviolet rays to make the recording layer a blue film. Next, the output is 3mW, the wavelength is 830nm,
A semiconductor laser beam with a beam diameter of 1 μm was used as input information and was irradiated at a predetermined position on the surface of each optical recording medium (irradiation time 200 ns/I pit) to form a red recorded image on the blue recording layer.

The evaluation of the recording results 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 0, and those that could not be recorded or were poor were evaluated as ×.

Table 1 Comparative Example 3 Same as in Example] without using the diacetylene derivative compound, but using a solution prepared by dissolving 11 parts by weight of a diene compound and 1 part by weight of nitrocellulose in 4 parts by weight of methylene chloride as the coating solution. An optical recording medium with a recording layer thickness of 2,500 mm was prepared by the method described above.

Recording Test 2 The irradiation time of the semiconductor laser beam was variously changed for the optical recording medium having the 41-layer mixed monomolecular cumulative film prepared in Example 3 (irradiation time 100 to 800 ns/1 chip).
Recording was performed in the same manner as in Recording Test 1, except for the following.

Moreover, regarding the optical recording medium of Comparative Example 3, ultraviolet irradiation! )
Alternatively, the semiconductor laser beam may be directly used as input information without performing t, or the laser beam may be irradiated onto the surface of the recording layer with the same output at a predetermined position on the surface of the recording medium with various irradiation times (irradiation time: 500
recording was performed by forming bits.

Regarding the optical recording medium of Example 3, the irradiation time was 200
Were you able to perform especially good recording in the case of ns or more?
Regarding the optical recording medium prepared in Comparative Example 3''C, as a result of observation with a microscope, it was found that it takes 2.5 to clearly form one bit.
It was found that an irradiation time of ns or more was required.

Example 5 General formula C+2H?・, CEC-CEC-CoHz, -
Instead of the diacetylene derivative compound represented by COOH, the general formula Cl1H+, -C:C-CEC-C7Hn-C
An optical recording medium was prepared in the same manner as in Example 2 except that a diacetylene derivative compound represented by OOH was used.

Example 6~;0 Compound Notification Same as Example 5 except that the diene compound salts represented by Compounds 3.8, 12.15 and 20 were used in place of the diene compound salt represented by 1. An optical recording medium was prepared by the method.

Recording Test 3 A recording test was conducted in the same manner as Recording Test 1 using the optical recording media prepared in Examples 5 to 10. 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. Diene compound salt

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 represents an alkyl group or a substituent. Represents a phenyl group or styryl group that may have R^2 and R^
6 represents an arylene group which may have a substituent that forms a conjugated double bond system with two adjacent -CH=CH- groups, and R^3 and R^7 have a substituent. R^4 represents an alkoxy group, R^5 represents an alkyl group, and A represents an anionic residue. )