JPH058537A - Optical record medium and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an optical record medium capable of recording with excellent contrast and high reliability, and performing recording and deleting repeatedly without fail. CONSTITUTION:On a support 1, a heat mode optical record layer 3 is provided. The heat mode optical record layer 3 is constituted of at least electron donative coloring compound and electron acceptive compound, reversibly having a coloring state to be obtained by heating it to a temperature higher than a coloring temperature and cooling it, and a decoloring state to be obtained by heating it to a temperature lower than the coloring temperature and cooling it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat mode optical recording medium for recording and erasing information by utilizing heat applied by light irradiation and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a so-called heat mode recording system has been put into practical use in which information is applied in the form of thermal energy and recorded as a change in shape or a change in physical properties of a recording material.
As such a heat mode recording medium, Te, B
An inorganic recording medium using a metal material containing i, Se, Tb, In as a main component, or a polymethine dye such as cyanine, a macrocyclic azaannulene dye such as phthalocyanine, naphthalocyanine, and porphyrin, naphthoquinone, anthraquinone Recording media using organic dyes such as dyes and dithiol metal complex dyes are known. When heat energy is applied to these recording media by irradiation with focused laser light, the recording layer in the irradiated portion is melted or evaporated to form holes (pits) and information is recorded. However, these recording media do not have the reversibility of erasing recorded information and recording new information again.

With the development of the read-only and write-once type heat mode optical recording medium as described above, the need for a reversible recording medium capable of recording, reproducing and erasing is increasing.

As such a reversible recording medium, for example, G
There is a magneto-optical recording medium using an alloy thin film composed of a rare earth metal such as d, Tb and Dy and a transition metal such as Fe, Ni and Co. In this, recording is performed by using heating by irradiation of laser light and an externally applied magnetic field in combination, and reproduction is performed by utilizing the difference in the rotation direction of the vibrating surface of light depending on the direction of magnetization. Information is erased by heating with a laser and applying an external magnetic field in the opposite direction to that during recording. But,
This magneto-optical recording medium does not have sufficient sensitivity during reproduction and the S / N
It has drawbacks such as poor recording ratio and deterioration of recording sensitivity and recording stability due to oxidation.

As reversible recording media, Ge, Te,
There is one utilizing a phase transition between crystal and amorphous of a recording layer formed of an inorganic material thin film containing an element such as Se, Sb, In and Sn as a main component. This recording medium has the advantage that recording and erasing can be performed in heat mode only by irradiation with laser light, but the contrast between the recording and non-recording areas and the recording stability are not sufficient, and the stability of the material of the recording layer It has drawbacks such as problems. In addition, JP-A-61-2
No. 37684 discloses a rewritable optical recording medium using a compound such as phenolphthalene, thymolphthalene or bisphenol as a developer. This product can be decolored by heating it and gradually cooling it to form a color-forming material, while heating the color-forming material once to a temperature higher than the color density and then rapidly cooling it. However, in the case of this optical recording medium, the process of coloring and erasing is complicated, and some color is still seen in the erasable body obtained by erasing the chromophore, and recording with good contrast is obtained. I can't.

[0006]

As described above, the conventional optical recording medium has various problems such as recording sensitivity, erasing speed, recording stability, and recording contrast. In particular, the contrast of recording is related to the recording speed and the reliability at the time of reproduction, and high contrast is required.

From this point of view, the present invention provides an optical recording medium capable of high-contrast recording utilizing the color development of an electron-donating color-forming compound and an electron-accepting compound as a material for a recording layer, and a method for producing the same. To do.

[0008]

The inventors of the present invention have studied the color development by an electron-donating color-forming compound and an electron-accepting compound utilizing heat accompanying light irradiation for the above-mentioned purposes, and as a result, It has been found that reversible recording and erasing can be performed by combining materials and controlling heating conditions, and the above object can be achieved.

That is, according to the present invention, a support is composed of at least an electron-donating color-forming compound and an electron-accepting compound, and the color-developing state and the temperature lower than the color-developing temperature obtained by heating to or above the color-developing temperature. There is provided an optical recording medium comprising a heat mode optical recording layer capable of reversibly taking a decolored state obtained by heating to an erasing temperature and cooling.

In the above structure, an electron-accepting compound is used.
Use an organophosphate compound represented by the following general formula
Preferably. R₁-PO (OH)₂ (However, R₁Is a straight or branched chain having 8 to 30 carbon atoms
Represents an alkyl group or an alkenyl group. ) Also on
In the above constitution, as the electron-accepting compound, the following general formula
Use an organic acid with a hydroxyl group at the α-position carbon
It is preferable. R₂-CH (OH) COOH (However, R₂Is a linear or branched chain having 6 to 28 carbon atoms
Represents an alkyl group or an alkenyl group. ) Also on
In the above constitution, the electron accepting compound is represented by the following general formula.
It is preferred to use the indicated thiomalic acid. (However, R₃Is a linear or branched chain having 6 to 28 carbon atoms
Represents an alkyl group or an alkenyl group. ) Also on
In the above structure, a halogen compound is used as the electron-donating color developing compound.
With or without an electron-donating color-forming compound
It is preferable to use the compound represented by the general formula 1.
Yes.

[Chemical 1] (However, R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₂ is a hydrogen atom or an optionally substituted amino group, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenylamino group. , M is an integer of 1 or 2, Y is an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 2 carbon atoms, and n is an integer of 1 or 2.)

Furthermore, according to the present invention, there is provided a method for producing the above optical recording medium, wherein a mixed melt of an electron-donating color-forming compound and an electron-accepting compound is held on a support and then rapidly cooled. There is provided a method for producing an optical recording medium, which is characterized in that the entire surface is once brought into a color-developed state, and then the entire surface is heated to a decoloring temperature lower than the color-developing temperature, and then cooled to obtain the entire surface-decolored state.

The recording layer of the present invention is a layer composed of an electron-donating color-forming compound and an electron-accepting compound. When heated and cooled to a temperature not lower than the color-developing temperature, the color-developing state is kept stable and the color-erasing temperature is lower than the color-developing temperature. When heated and cooled, the decolored state is kept stable.

The relationship between the recording / erasing and the temperature will be described with reference to FIG. The vertical axis in FIG. 1 represents the color density and the horizontal axis represents the temperature. The solid line 1 shows the recording formation process by heating and the broken line 3 shows the recording erasing process by heating. A is the concentration in the completely erased state, and B is T ₁
The density in a completely colored state when heated to the above temperature, C is the density at a temperature of T ₀ or less in the completely colored state, and D is the density when heat-erased at a temperature between T _{0 and} T _1. Shows.

The recording layer in the present invention is in a colorless state (A) at a temperature of T ₀ or lower, for example. At the time of recording, the color is developed (B) by heating to a temperature of T ₁ or higher by the heat accompanying light irradiation to form a record. Even if this recording is returned to the temperature of T ₀ or less according to the solid line 2, the state (C) is kept as it is and the memory property of the recording is not lost.

Next, in order to erase the record, the formed record is heated to a temperature between T _{0 and} T _{1 which} is lower than the color development temperature, and the state becomes colorless (D). In this state, the colorless state (A) is maintained as it is even when the temperature is returned to T ₀ or lower. That is, the process of forming the record reaches C by the path of the solid line ABC and the record is held. Next, in the erasing process of recording, the erasing state is maintained by reaching A by the path of the broken line CDA. The recording and erasing behavior characteristics are reversible and can be repeated many times.

Recording in the present invention is performed by irradiation with light energy. Specifically, a laser beam focused in a small amount is applied to the recording layer while moving relatively according to information. When the recording layer absorbs the light used for recording, the light absorbed in the recording layer becomes thermal energy and heats the recording layer. When the recording layer does not absorb light, it may be in contact with the recording layer or a separate light absorbing layer may be provided near the recording layer. This layer functions as a light-heat conversion layer, the generated heat is transmitted to the recording layer, and the recording layer is heated. Recording can be performed in the same manner by adding a photothermal conversion substance that absorbs light and changes into heat into the recording layer.

FIG. 2 shows the basic structure of the optical recording medium of the present invention. In (a), the heat mode optical recording layer 3 is provided on the support 1, and in this case, a photothermal conversion substance is added to the heat mode optical recording layer 3 as needed.
In (b), the photothermal conversion layer 2 is provided on the support 1, and the heat mode optical recording layer 3 is further provided thereon. Further, (c) shows that the protective layer 4 is further provided on the optical recording medium of (b).

The photothermal conversion layer of the optical recording medium used in the present invention may be a metal or semimetal layer such as platinum, titanium, silicon, chromium, nickel, germanium or aluminum, and reflects a part of light. It can also be used as a reflection layer, and is particularly advantageous in terms of configuration when reproducing using reflected light.

Examples of the light absorber used for photothermal conversion include azo dyes, cyanine dyes, naphthoquinone dyes, anthraquinone dyes, squarylium dyes, phthalocyanine dyes, naphthalocyanine dyes, naphthoquinone dyes, A porphyrin type dye, an indigo type dye, a dithiol complex type dye, an azurenium type dye, a quinone imine type dye, a quinone dimiine type dye, etc. can be used, and the light absorber is selected according to the wavelength of light used for recording and erasing.

Among the materials used for the heat mode optical recording layer of the present invention, the following compounds can be used as the electron-donating color developing compound. These are compounds exhibiting an electron donating property, and are themselves colorless or light-colored dye precursors, and are not particularly limited, and conventionally known compounds such as triphenylmethanephthalide compounds, fluoran compounds, and phenothiazine compounds. There are compounds, leuco auramine-based compounds, rhodamine lactam-based compounds, spiropyran-based compounds, indolinophtalide-based compounds and the like, and specific examples thereof include the following. 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide 3,3-bis (p
-Dimethylaminophenyl) -6-chlorophthalide,
3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-
Diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np
-Tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino } -6-Diethylaminofluorane, 2- {3,6-bis (diethylamino) -6- (o
-Chloranilino) xanthyl benzoate lactam}, 3
-Diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7
-(O-chloranilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-N
-Methyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- Anilino Fluoran, 3
-(N, N-diethylamino) -5-methyl-7-
(N, N-dibenzylamino) fluorane, benzoleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-2'-
Methoxy-benzoindolino-spiropyran, 3-
(2'-hydroxy-4'-dimethylaminophenyl)
-3- (2'methoxy-5'-chlorophenyl) phthalide, 3- (2'hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- ( 2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4 '
-Dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methoxyphenyl) phthalide,
3-morpholino-7- (N-propyl-trifluoromethylaniline) fluorane, 3-diethylamino-5-
Chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenyl Ethylamino) fluorane, 3- (N-ethyl-p-toluidino)
-7- (α-phenylethylamino) fluorane, 3-
Diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3
-Diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methoxytoluidino) -7- (pn
-Butylanilino) fluorane, 3- (N-methyl-N)
-Isopropylamino) -6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorene spiro (9,3 ')- 6'-Dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4 '
-Bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2
-Ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane,
3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane, 3-N-methyl-N-
Isobutyl-6-methyl-7-anilinofluorane, 3
-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7
-(2 ', 4'-dimethylanilino) fluorane and the like.

Particularly preferred color formers used in the present invention are those containing halogen as a substituent. Examples of such a thing include the following. 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3-cyclohexylamino-6-chlorofluorane, 3-cyclohexylamino-6-bromofluorane, 3-diethylamino-7-chlorofluorane, 3 -Diethylamino-7-bromofluorane, 3-
Dipropylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-phenylamino-fluorane, 3-pyrrolidino-6-chloro-7-phenylamino-fluorane, 3-diethylamino-6-chloro-7-
(M-Trifluoromethylphenyl) amino-fluorane, 3-cyclohexylamino-6-chloro-7- (o
-Chlorophenyl) amino-fluorane, 3-diethylamino-6-chloro-7- (2 ', 3'dichlorophenyl) amino-fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-dibutylamino -6
-Chloro-7-ethoxyethylamino-fluorane, 3
-Diethylamino-7- (o-chlorophenyl) amino-fluorane, 3-diethylamino-7- (o-bromophenyl) amino-fluorane, 3-diethylamino-
7- (o-chlorophenyl) amino-fluorane, 3-
Dibutylamino-7- (o-fluorophenyl) amino-fluorane, 6'-bromo-3'-methoxybenzoindolino-pyrrilospirane, 3- (2'-methoxy-
4'-Dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2 '-Methoxy-5'-chlorophenyl) phthalide, 2- {3,6-bis (diethylamino)}-9- (o-chlorophenyl) amino-xanthyl lactam benzoate and the like.

A preferred color former for use in the present invention is a compound represented by the following general formula 1.

[Chemical 1] (However, R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₂ is a hydrogen atom or an optionally substituted amino group, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenylamino group. , M is an integer of 1 or 2, Y is a carbon number 1
An alkyl group having 4 to 4 or an alkoxy group having 1 to 2 carbon atoms,
n represents an integer of 1 or 2. )

Specific examples of the compound represented by the general formula 1 include the followings. 3- (N-methyl-N-phenylamino) -7-amino-fluorane, 3- (N-ethyl-N-phenylamino) -7-amino-fluorane, 3- (N-propyl-)
N-phenylamino) -7-amino-fluorane, 3-
{N-methyl-N- (p-methylphenyl) amino}-
7-amino-fluorane, 3- {N-ethyl-N- (p
-Methylphenyl) amino} -7-amino-fluorane, 3- {N-propyl-N- (p-methylphenyl)
Amino} -7-amino-fluorane, 3- {N-methyl-N- (p-ethylphenyl) amino} -7-amino-
Fluorane, 3- {N-ethyl-N- (p-ethylphenyl) amino} -7-amino-fluorane, 3- {N-
Propyl-N- (p-ethylphenyl) amino} -7-
Amino-fluorane, 3- {N-methyl-N- (2 ',
4'-Dimethylphenyl) amino} -7-amino-fluorane, 3- {N-ethyl-N- (2 ', 4'-dimethylphenyl) amino} -7-amino-fluorane, 3-
{N-propyl-N- (2 ', 4'-dimethylphenyl)
Amino} -7-amino-fluorane, 3- {N-methyl-N- (p-chlorophenyl) amino} -7-amino-
Fluorane, 3- {N-ethyl-N- (p-chlorophenyl) amino} -7-amino-fluorane, 3- {N-
Propyl-N- (p-chlorophenyl) amino} -7-
Amino-fluorane, 3- (N-methyl-N-phenylamino) -7-methylamino-fluorane, 3- (N-
Ethyl-N-phenylamino) -7-methylamino-fluorane, 3- (N-propyl-N-phenylamino)-
7-methylamino-fluorane, 3- {N-methyl-N
-(P-methylphenyl) amino} -7-ethylamino-fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -7-benzylamino-fluorane,
3- {N-methyl-N- (2 ', 4'-dimethylphenyl) amino} -7-methylamino-fluorane, 3-
{N-ethyl-N- (2 ', 4'-dimethylphenyl) amino} -7-ethylamino-fluorane, 3- {N-methyl-N- (2', 4'-dimethylphenyl) amino}-
7-benzylamino-fluorane, 3- {N-ethyl-
N- (2 ', 4'-dimethylphenyl) amino} -7-benzylamino-fluorane, 3- (N-methyl-N-phenylamino) -7-dimethylamino-fluorane, 3
-(N-ethyl-N-phenylamino) -7-dimethylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -7-diethylamino-fluorane, 3- {N-ethyl- N- (p-methylphenyl) amino} -7-diethylamino-fluorane, 3- (N-
Methyl-N-phenylamino) -7-dipropylaminofluorane, 3- (N-ethyl-N-phenylamino)-
7-dipropylaminofluorane, 3- {N-methyl-
N- (p-methylphenyl) amino} -7-dibenzylamino-fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -7-dibenzylamino-fluorane, 3- {N- Ethyl-N- (p-methylphenyl) amino} -7-di (p-methylbenzyl) amino-
Fluoran, 3- {N-methyl-N- (p-methylphenyl) amino} -7-acetylamino-fluorane, 3
-{N-ethyl-N- (p-methylphenyl) amino}
-7-benzoylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -7- (o-
Methoxybenzoyl) amino-fluorane, 3- {N-
Ethyl-N- (p-methylphenyl) amino} -6-methyl-7-phenylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -6-methyl-7-phenylamino -Fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -6-ter
t-Butyl-7- (p-methylphenyl) amino-fluorane, 3- {N-ethyl-N-phenylamino) -6
-Methyl-7-ethyl-N- (p-methylphenyl) amino-fluorane, 3- {N-propyl-N- (p-methylphenyl) amino} -6-methyl-7- {N-methyl-N- (P-Methylphenyl) amino} -fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -5-methyl-7-benzylamino-fluorane, 3- {N-ethyl-N- ( p-methylphenyl) amino} -5-chloro-7-dibenzylamino-fluorane, 3- {N-methyl-N- (p-methylphenyl) amino} -5-methoxy-7-dibenzylamino-fluorane, 3- {N-ethyl-N- (p-methylphenyl)
Amino} -6-methyl-fluorane, 3- {N-ethyl-N- (p-methylphenyl) amino} -5-methoxy-fluorane and the like.

Among the materials used for the heat mode recording layer of the recording medium of the present invention, the following compounds can be used as the electron accepting compound. (1) Organic phosphoric acid compound R ₁ —PO (OH) ₂ (1) represented by the following general formula (1) (wherein R ₁ is a linear or branched alkyl group or alkenyl having 8 to 30 carbon atoms) Represents a group.) Specific examples of the organic phosphoric acid compound include the following. Octylphosphonic acid, nonylphosphonic acid,
Decylphosphonic acid, dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid.

(2) An organic acid having a hydroxyl group at the α-position carbon represented by the following general formula (2). R ₂ —CH (OH) COOH (2) (wherein R ₂ represents a linear or branched alkyl group or alkenyl group having 6 to 28 carbon atoms) Specific examples of the organic acid having a hydroxyl group at the α-position carbon For example, for example,
The following are listed. α-hydroxyoctanoic acid, α-hydroxydodecanoic acid, α-hydroxytetradecanoic acid,
α-Hydroxyhexadecanoic acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid, α-hydroxyeicosanoic acid, α-hydroxydocosanoic acid and the like.

(3) Thiomalic acid represented by the following general formula (3). (However, R ₃ represents a linear or branched alkyl group having 6 to 28 carbon atoms or an alkene group.) Specific examples include octadecyl thiomalic acid, eicosyl thiomalic acid, and docosyl thiomalic acid. , Tetracosyl thiomalic acid, etc.

In the production of the recording medium of the present invention, there are the following methods for forming the recording layer. When the recording layer is protected with an electron-donating color-forming compound and an electron-accepting compound by using a resin binder, they can be provided by dissolving them in a suitable solvent and coating and drying. Further, these materials can be dispersed and applied in a resin solution using a ball mill or the like. These methods are advantageous in manufacturing because ordinary coating methods such as spin coating and dipping can be used.

As the resin, various conventional resins can be appropriately used, and examples thereof include polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, methoxy cellulose, carboxymethyl cellulose, methyl cellulose, cellulose acetate, gelatin, casein, starch and polyacrylic acid. Soda, polyvinylpyrrolidone, polyacrylamide, maleic acid copolymer,
Acrylic acid copolymer, polystyrene, polyvinyl chloride, polyvinyl acetate, polyacrylic acid esters, polymethacrylic acid esters, vinyl chloride / vinyl acetate copolymer, styrene copolymer, polyester, polyurethane and the like.

When the recording layer is formed without using a resin, the following method can be adopted. A recording layer can be formed by holding a melt obtained by mixing and melting an electron-donating color-forming compound and an electron-accepting compound on a heated support in a thin film form and cooling from that state. Since the recording layer thus formed is not a dispersed state but a crystalline film, it is suitable for high density recording.

The recording method using the optical recording medium of the present invention is as follows.
Color development using an electron-donating color-forming compound and an electron-accepting compound is used, but there are two cases. One is to form and record spots in the color-developed state on the recording layer in the color-erased state, and the other is to form and record spots in the color-erased state to the recording layer in the color-developed state.

When the recording in the color-developed state is used, the entire surface of the recording layer can be erased in the initial state as follows. When the color is developed in the melt-mixed state and gradually cooled, the erasing temperature is slowly passed, so that a state in which the entire surface is decolored is obtained. In addition, quenching from the state of color development in the melt mixed state,
Once the entire surface is in a color-developed state, and then the temperature is raised to the decoloring temperature and cooled, the fully-decolored state is obtained. The latter method is easy to obtain a uniform state on the entire surface and is preferable for high density recording.

When the recording in the decolored state is used, the state in which the color is developed in the melt-mixed state may be rapidly cooled so that the entire surface is in the colored state.

As can be seen from the relationship between color development and color erasure of the recording layer of the present invention and temperature (FIG. 1), color development may be carried out by heating and cooling above a certain temperature, and the color erasing will occur within a certain temperature range lower than this. It needs to be heated and cooled. Therefore, as for the irradiation condition, it is more permissible to create a colored state, and generally high speed is required. It is easier to set up the system when the recording is formed by forming the coloring state.

As the substrate of the optical recording medium of the present invention, a commonly used glass plate or plastic plate such as acrylic resin or polycarbonate resin can be used. The protective layer is
A transparent layer for recording light, reproducing light, erasing light such as glass or resin can be used.

[0035]

EXAMPLES The present invention will now be described in more detail by way of examples. In addition, "part" in an Example is a weight part.

Example 1 A Cr layer serving as a photothermal conversion layer was provided by vacuum evaporation on an optically polished glass disk having a diameter of 101.6 mm and a thickness of 1.2 mm. The thickness was 950Å. This board 1
A Cr layer was placed on a hot plate controlled at 50 ° C., powders of an electron-donating color-developing compound and an electron-accepting compound, which had been pulverized and mixed with the following composition, were placed thereon and melted. 3-dibutylamino-7- (o-chlorophenyl) aminofluorane 25 parts Octadecylphosphonic acid 30 parts Next, cover the melt with a 0.1 mm glass plate, spread the melt evenly over the entire surface, and then scissor it. Complicated. The melt layer was in a uniform color-developed state at this temperature. Next, this disk was put into ice water and rapidly cooled to solidify the melt layer in a colored state. After the glass plate was peeled off, a 5 wt% aqueous solution of polyvinyl alcohol was applied onto this color-developing layer and dried to form a protective layer. Next, this disk is evenly heated to 70 in a constant temperature bath.
The recording layer was heated to 0 ° C., kept for 5 minutes, and then allowed to cool to bring the entire recording layer into a substantially transparent decolored state to obtain an optical recording medium according to the present invention.

The optical recording medium prepared in this way is
While moving at mm / s, laser light having a wavelength of 780 nm focused on a diameter of 5 μm was irradiated. The intensity of the laser beam was set to 8 mW on the surface of the optical recording medium. After recording, when the recorded portion was observed with an optical microscope, it was confirmed that a black line-shaped recording was formed. Next, the recorded optical recording medium was heated to 70 ° C. in a constant temperature bath, immediately taken out, and when the recorded portion was observed, it was confirmed that the recording was completely erased.

Example 2 One glass disk provided with the same Cr vapor deposition film as in Example 1 was used.
The mixture was heated to 25 ° C., a powder having the same composition as in Example 1 was placed thereon, and a cover glass was put on it to form a layer in a colored state, and then the whole was gradually cooled to form a layer in a decolored state. A 5 wt% aqueous solution of polyvinyl alcohol was applied onto this recording layer,
It was dried to form a protective layer. When the optical recording medium thus prepared was irradiated with laser light in the same manner as in Example 1, it was confirmed that black line-shaped recording was formed on the recording portion. Further, the heat treatment at 70 ° C. made it possible to erase the record.

Example 3 An optical recording medium was prepared in the same manner as in Example 1 except that the combination of the electron-donating color developing compound and the electron-accepting compound used in Example 1 was changed to the one having the following composition. did. 3-Dibutylamino-7- (o-chlorophenyl) aminofluorane 25 parts Eicosylthiomalic acid 30 parts This optical recording medium was irradiated with laser light in the same manner as in Example 1 to confirm the formation of recording. Also, it was confirmed that erasing was possible in the same manner.

Example 4 An optical recording medium was prepared in the same manner as in Example 2 using the combination of the electron-donating color developing compound and the electron-accepting compound used in Example 3. This optical recording medium was irradiated with laser light in the same manner as in Example 1 to confirm the formation of recording. Also, it was confirmed that erasing was possible in the same manner.

Example 5 The following composition was stirred and dissolved to prepare a recording layer coating solution. 3- {N-ethyl-N- (p-methylphenyl) amino} -7-phenylaminofluorane 10 parts Octadecylphosphonic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH: Union Carbide) 45 parts Tetrahydrofuran 450 The coating liquid was applied onto a glass disk provided with a Cr vapor deposition film and dried to form a recording layer, as in Example 1, to obtain an optical recording medium according to the present invention. Example 1 was applied to this optical recording medium.
The formation of recording was confirmed by irradiating the same with laser light. Also, it was confirmed that erasing was possible in the same manner.

Example 6 The following composition was stirred and dissolved to prepare a recording layer coating liquid.   3-dibutylamino-7- (o-chlorophenyl) aminofluorane 10 parts   Eicosyl thiomalic acid 30 parts   Naphthalocyanine dye (the following structural formula 2) 3 parts   Vinyl chloride-vinyl acetate copolymer (VYHH: Union Carbide) 45 parts   Tetrahydrofuran 450 parts

[Chemical 2] This coating solution was applied onto the same glass disk as in Example 1 as it was and dried to form a recording layer, which was used as an optical recording medium according to the present invention. The formation of recording was confirmed by irradiating the optical recording medium with laser light in the same manner as in Example 1 except that the intensity was set to 12 mW. Also, it was confirmed that erasing was possible in the same manner.

Example 7 The following composition was stirred and dissolved to prepare a recording layer coating liquid. 3- {N-ethyl-N- (p-methylphenyl) amino)}-7-phenylaminofluorane 10 parts α-hydroxydocosanoic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH: Union Carbide Co.) 45 parts Tetrahydrofuran 450 parts This coating solution was applied onto a glass disk provided with a Cr vapor deposition film and dried to form a recording layer, as in Example 1, to obtain an optical recording medium according to the present invention. Example 1 was applied to this optical recording medium.
The formation of recording was confirmed by irradiating the same with laser light. Also, it was confirmed that erasing was possible in the same manner.

Comparative Example An optical recording medium was prepared in the same manner as in Example 1 except that the combination of A or B shown below was used instead of the electron-donating color developing compound and the electron-accepting compound used in Example 1. ,
I tried to record and erase. As a result, the record was formed,
It could not be erased. [A] 3- (N-cyclohexyl-N-methylphenyl) amino-7-phenylaminofluorane 25 parts octadecylphosphonic acid 30 parts [B] 3-diethylamino-6-methyl-7-phenylaminofluorane 25 parts octadecyl Phosphonic acid 30 parts

[0045]

According to the optical recording medium of the present invention, it is possible to realize a system in which high-contrast and high-reliability recording can be performed, and repetitive recording and erasing can be reliably performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a color density and a temperature of a recording layer used in the present invention, and a diagram for explaining a color developing and erasing principle. The solid line A → B → C indicates the recording formation process, and the broken line C → D → A.
Indicates the erasing process.

FIG. 2 is a diagram showing a basic configuration of an optical recording medium of the present invention.

[Explanation of symbols]

1 support 2 Photothermal conversion layer 3 recording layers 4 protective layer

Claims (6)

[Claims] 1. A support, which comprises at least an electron-donating color-forming compound and an electron-accepting compound, is heated to a coloration temperature or higher, and a coloring state obtained by cooling and heating to a decoloring temperature lower than the coloring temperature. An optical recording medium provided with a heat mode optical recording layer capable of reversibly obtaining a decolored state obtained by cooling. 2. The electron-accepting compound is represented by the following general formula.
An organic phosphoric acid compound
1. The optical recording medium according to 1. R₁-PO (OH)₂ (However, R₁Is a straight or branched chain having 8 to 30 carbon atoms
Represents an alkyl group or an alkenyl group. ) 3. The optical recording medium according to claim 1, wherein the electron-accepting compound is an organic acid having a hydroxyl group at the α-position carbon represented by the following general formula. R ₂ —CH (OH) COOH (wherein R ₂ represents a linear or branched alkyl group having 6 to 28 carbon atoms or an alkenyl group). 4. The electron-accepting compound is thiomalic acid represented by the following general formula:
The optical recording medium according to any one of 1. (However, R ₃ represents a linear or branched alkyl group or alkenyl group having 6 to 28 carbon atoms.) 5. The electron-donating color-forming compound is a halogen-containing electron-donating color-forming compound or a compound represented by the following general formula (1). An optical recording medium according to item. [Chemical 1] (However, R ₁ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₂ is a hydrogen atom or an optionally substituted amino group, X is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a phenylamino group. , M is an integer of 1 or 2, Y is an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 2 carbon atoms, and n is an integer of 1 or 2.) 6. The method for producing an optical recording medium according to claim 1, wherein a mixed melt of an electron-donating color-forming compound and an electron-accepting compound is held on a support. After that, it is rapidly cooled to once bring the entire surface into a color-developed state, and subsequently, the whole is heated to a decoloring temperature lower than the coloring temperature and then cooled to bring the entire surface into a decolored state.