JPH0999641A - Reversible thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermal recording medium holding stable color forming and erasing properties and capable of corresponding to a wide range of use conditions and environmental conditions. SOLUTION: In a reversible thermal recording medium wherein a recording layer containing a color former and a couper as main components and capable of relatively forming a developed color state and an erased color state by the difference between heating temp. and cooling temp. after heating and a display member, the amt. of a binder resin is 3.0-8.0 pts.wt. per 1 pts.wt. of the sum of the dye being the color former and the coupler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording medium utilizing a color-forming reaction between an electron-donating color-forming compound and an electron-accepting compound, more specifically, a color-developed image by controlling heat energy. The present invention relates to a reversible thermosensitive recording medium capable of forming and erasing data.

[0002]

2. Description of the Related Art Conventionally, an electron-accepting color-forming compound (hereinafter, referred to as an electron-accepting color-forming compound)
Thermal recording media utilizing a color development reaction between a color former or a leuco dye and an electron-accepting compound (hereinafter also referred to as a developer) are widely known, such as facsimile machines, word processors, and scientific measuring instruments. Used in printers. However, these conventional recording media that have been put into practical use all have irreversible color development, and once recorded images cannot be erased and used repeatedly. On the other hand, according to the patent publication, a recording medium capable of reversibly developing and erasing color is also proposed, for example, JP-A-60-193691 which uses a combination of gallic acid and phloroglucinol as a developer. JP-A-61-237684, which uses a compound such as phenolphthalein or thymolphthalein as a color developer, and JP-A-61-237684, which contains a homogenous solution of a color developer, a color developer, and a carboxylic acid ester in a recording layer. 62-138556, JP-A-62-138568.
And JP-A-62-140881, JP-A-63-17368 using an ascorbic acid derivative as a color developer.
No. 4, JP-A-2-188293 and JP-A-2-18829 in which a salt of bis (hydroxyphenyl) acetic acid or gallic acid and a higher aliphatic amine is used as a color developer.
No. 4, etc. are disclosed. However, the conventional reversible thermosensitive recording medium described above has a problem in terms of compatibility between color stability and decoloration, or stability in color density and repetition, and practical recording. It is not satisfactory as a medium.

The applicant of the present invention has previously filed Japanese Patent Application Laid-Open No. 5-124360.
In the publication, an organic phosphoric acid compound having a long-chain aliphatic hydrocarbon group, an aliphatic carboxylic acid compound or a phenol compound is used as a color developing agent, and by combining this with a leuco dye which is a color developing agent, color development and decolorization can be achieved. Reversible coloring that can be easily performed under heating and cooling conditions, and that the colored and decolored states can be maintained stably at room temperature, and that coloring and decoloring can be repeated stably. A composition and a reversible thermosensitive recording medium using the same as a recording layer have been proposed. This has practical performance in terms of the balance between color stability and color erasure and color density, but it is also improved in terms of compatibility with a wider range of usage environments and the range of application of color erasure conditions. There was room to be. Since then, it has been proposed to use a specific structure for a phenol compound having a long-chain aliphatic hydrocarbon group (Japanese Patent Laid-Open Publication No. H6 (1994) -6 (1980)).
-210954), which had the same problem.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reversible thermosensitive recording medium which maintains stable coloring and decoloring properties and can be used in a wide range of use conditions and environmental conditions.

[0005]

As a result of intensive studies, the present inventors have found that the reversible color-forming composition and reversible thermosensitive recording medium have a reversible color-forming composition and a reversible thermosensitive recording medium in which the weight part ratio of the sum of dye and color developer as a color-forming material and the binder resin is reversible. It was found that it affects storage conditions such as properties and heat resistance, and that the weight part ratio of the dye and the developer, which is the color forming material of the reversible recording medium, is the repetitive property of the reversible color forming composition and the reversible thermosensitive recording medium. It has been found that it affects storage conditions such as heat resistance. Then, the inventors have further studied the conditions for optimizing such characteristics and completed the present invention.
That is, the present invention includes (1) a recording which contains a color former and a developer as main components and can form a relatively colored state and a decolored state depending on a difference in heating temperature and / or cooling temperature after heating. In the reversible recording medium in which the layer is provided on the support, the binder resin is present in an amount of 3.0 parts by weight to 8.0 parts by weight with respect to 1 part by weight of the sum of the dye as the color former and the developer. Characteristic reversible recording medium.

(2) In the reversible thermosensitive recording medium of the above (1), the developing agent is added to 1 part by weight of the dye which is a coloring agent.
It relates to a reversible recording medium, characterized in that it is between 5 parts by weight and 5.0 parts by weight. As shown in the above (1), if the binder resin is present in the range of 3.0 to 8.0 parts by weight per 1 part by weight of the sum of the color-forming component, the dye and the developer, the film will be damaged by repeated tests. Good results in storage stability such as heat resistance can be obtained. Further, in addition to the above conditions, if the developer is 2.5 parts by weight to 5.0 parts by weight with respect to 1 part by weight of the dye, which is the coloring material of the reversible recording medium, the repetitive characteristics, heat resistance, etc. are preserved. Conditions are improved.

If the binder resin is between 3.0 parts by weight and 8.0 parts by weight with respect to 1 part by weight of the sum of the dye which is a color forming component and the microscopic coloring agent, the heat resistance is not impaired by the repeated test without damaging the film. Good results are obtained in terms of storage stability.
In particular, the value is preferably between 2.5 parts by weight and 3.5 parts by weight. When the value is less than 3.0 parts by weight, dents are remarkably generated due to repeated printing, and storage characteristics and repeatability are deteriorated. On the contrary, when the value is larger than 8.0 parts by weight, the thermal sensitivity is deteriorated and a sufficient color density cannot be obtained. Further, in addition to the above conditions, if the developer is 2.5 parts by weight to 5.0 parts by weight with respect to 1 part by weight of the dye, which is the coloring material of the reversible recording medium, the repetitive characteristics, heat resistance, etc. are preserved. Conditions are improved. Particularly, the value is preferably between 3.5 parts by weight and 4.5 parts by weight. Its value is 2.
If it is less than 5 parts by weight, the color density of printing is too low, and it becomes difficult for the machine to recognize it by a bar code reader or the like. On the contrary, when the value is larger than 5.0 parts by weight, the fineness of the printed image is lacked and the storage characteristics and the repeating characteristics are deteriorated. The color developer used in the reversible thermosensitive recording medium of the present invention will be described.

In the reversible thermosensitive recording medium of the present invention, the color developing agent used in combination with the color developing agent has a structure showing a color developing ability capable of developing the color developing agent in the molecule and a cohesive force between the molecules. It is a compound that also has a long-chain structure part to control, and is an organic phosphoric acid compound having an aliphatic group having 12 or more carbon atoms, an aliphatic carboxylic acid compound having an aliphatic group having 12 or more carbon atoms, and an aliphatic compound having 12 or more carbon atoms. It is a phenol compound having a group. The aliphatic group includes linear or branched alkyl groups and alkenyl groups, halogen,
It may have a substituent such as an alkoxy group or an ester group. In the reversible thermosensitive recording medium of the present invention, an organic phosphoric acid compound having an aliphatic group having 12 or more carbon atoms is particularly preferable among the developers. Hereinafter, the color developer will be specifically exemplified. (A) Organic phosphoric acid compound, a compound represented by the following general formula (1) is used.

[0009] Specific examples of R ₁ -PO (OH) ₂ (1) (where, R ₁ represents a number of 12 or more aliphatic groups carbons) organic phosphoric acid compound represented by the general formula (1) may, for example, The following are listed. Dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid, hexacosylphosphonic acid, octacosylphosphonic acid and the like.

(B) Aliphatic carboxylic acid compounds and α-hydroxy fatty acids represented by the following general formula (2) are preferably used. R ₂ —CH (OH) —COOH (2) (where R ₂ represents an aliphatic group having 12 or more carbon atoms) Examples of the α-hydroxyaliphatic carboxylic acid compound represented by the general formula (2) include: One.
α-hydroxydodecanoic acid, α-hydroxytetradecanoic acid, α-hydroxyhexadecanoic acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid, α-
Hydroxy eicosanoic acid, α-hydroxy docosanoic acid,
α-hydroxytetracosanoic acid, α-hydroxyhexacosanoic acid, α-hydroxyoctacosanoic acid and the like.

The aliphatic carboxylic acid compound is an aliphatic carboxylic acid compound having an aliphatic group having 12 or more carbon atoms substituted with a halogen element, and having a halogen element at at least the α-position or β-position carbon. Is also preferably used. Specific examples of such a compound include the followings. 2-bromohexadecanoic acid, 2-bromoheptadecanoic acid, 2-bromooctadecanoic acid, 2-bromoeicosanoic acid, 2-bromodocosanoic acid, 2-bromotetracosanoic acid, 3-bromooctadecanoic acid, 3-bromoeicosanoic acid 2,2-dibromooctadecanoic acid, 2-fluorododecanoic acid, 2-fluorotetradecanoic acid, 2-fluorohexadecanoic acid, 2-fluorooctadecanoic acid, 2-fluoroeicosanoic acid, 2-
Fluorodocosanoic acid, 2-iodohexadecanoic acid, 2-
Iodooctadecanoic acid, 3-iodohexadecanoic acid, 3
-Iodooctadecanoic acid, perfluorooctadecanoic acid and the like.

The aliphatic carboxylic acid compound is an aliphatic carboxylic acid compound having an oxo group having 12 or more carbon atoms in the carbon chain, and at least the carbon at the α-position, β-position or γ-position is oxo. The underlying one is also used. Specific examples of such a compound include the followings. 2-oxododecanoic acid, 2
-Oxotetradecanoic acid, 2-oxohexadecanoic acid,
2-oxooctadecanoic acid, 2-oxoeicosanoic acid,
2-oxotetracosanoic acid, 3-oxododecanoic acid, 3
-Oxotetradecanoic acid, 3-oxohexadecanoic acid,
3-oxooctadecanoic acid, 3-oxoeicosanoic acid,
3-oxotetracosanoic acid, 4-oxohexadecanoic acid, 4-oxoheptadecanoic acid, 4-oxooctadecanoic acid, 4-oxodocosanoic acid and the like. As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (5) is also preferably used.

[0013]

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(Wherein R ₃ represents an aliphatic group having 12 or more carbon atoms, X represents an oxygen atom or a sulfur atom, and n represents 1 or 2) of the dibasic acid represented by the general formula (3). As a specific example,
For example, the following are mentioned. Dodecyl malate, tetradecyl malate, hexadecyl malate, octadecyl malate, eicosyl malate, docosyl malate, tetracosyl malate, dodecyl thiomalate, tetradecyl thiomalate, hexadecyl thiomalate,
Octadecylthiomalic acid, eicosylthiomalic acid,
Docosylthiomalic acid, tetracosylthiomalic acid, dodecyldithiomalic acid, tetradecyldithiomalic acid,
Hexadecyldithiomalic acid, octadecyldithiomalic acid, eicosyldithiomalic acid, docosyldithiomalic acid, tetracosyldithiomalic acid, etc. A dibasic acid represented by the following general formula (4) is also used as the aliphatic carboxylic acid compound.

[0015]

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(However, R ₄ , R ₅ and R ₆ represent a hydrogen atom or an aliphatic group, at least one of which has 1 carbon atom.
Specific examples of the dibasic acid represented by the general formula (4) are two or more aliphatic groups.
For example, the following are mentioned. Dodecyl butane diacid,
Tridecyl butane diacid, tetradecyl butane diacid, pentadecyl butane diacid, octadecyl butane diacid, eicosyl butane diacid, docosyl butane diacid, 2,3-dihexadecyl butane diacid, 2,3-dioctadecyl Butanedioic acid, 2-methyl-3-dodecylbutanedioic acid, 2-methyl-3-tetradecylbutanedioic acid, 2-methyl-3-hexadecylbutanedioic acid, 2-ethyl-3-dodecylbutanedioic acid, 2-propyl-3-dodecyl butane diacid, 2-octyl-3-hexadecyl butane diacid, 2-tetradecyl-3-octadecyl butane diacid, and the like. As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (5) is also used.

[0017]

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(Wherein R ₇ and R ₈ represent a hydrogen atom or an aliphatic group, and at least one of them represents an aliphatic group having 12 or more carbon atoms) of the dibasic acid represented by the general formula (5). As a specific example,
For example, the following are mentioned.

Dodecylmalonic acid, tetradecylmalonic acid, hexadecylmalonic acid, octadecylmalonic acid, eicosylmalonic acid, docosylmalonic acid, tetracosylmalonic acid, didodecylmalonic acid, ditetradecylmalonic acid, dihexadecylmalonic acid Acid, dioctadecyl malonic acid, dieicosylmalonic acid, didocosylmalonic acid, methyl octadecylmalonic acid, methyleicosylmalonic acid,
Methyl docosyl malonic acid, methyl tetracosyl malonic acid, ethyl octadecyl malonic acid, ethyl eicosyl malonic acid, ethyl docosyl malonic acid, ethyl tetracosyl malonic acid, etc. As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (6) is also used.

[0020]

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(However, R ₉ represents an aliphatic group having 12 or more carbon atoms, n represents 0 or 1, m represents 1, 2 or 3, and when n is 0, m is 2 or 3. Yes,
When n is 1, m represents 1 or 2. Specific examples of the dibasic acid represented by the general formula (6) include:
For example, the following are mentioned. 2-dodecyl-pentanedioic acid, 2-hexadecyl-pentanedioic acid, 2-octadecyl-pentanedioic acid, 2-eicosyl-pentanedioic acid, 2-docosyl-pentanedioic acid, 2-dodecyl-hexanedioic acid, 2- Pentadecyl-hexanedioic acid, 2-octadecyl-hexanedioic acid, 2-eicosyl-hexanedioic acid, 2-docosyl-hexanedioic acid and the like. As the aliphatic carboxylic acid compound, a tribasic acid such as citric acid acylated with a long chain fatty acid is also used. Specific examples thereof include the following.

[0022]

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(C) Phenol Compound As the phenol compound, a compound represented by the following general formula (7) is used.

[0024]

[Chemical 6]

(However, Y is -S-, -O-, -CON
H -, - NHCONH -, - NHSO 2 -, - CH = C
H-CONH- or -COO- a represents, R ₁₀ represents a number of 12 or more aliphatic group having a carbon, n is an integer of 1, 2 or 3). Specific examples of the phenol compound represented by the general formula (7) include the following.

P- (dodecylthio) phenol, p-
(Tetradecylthio) phenol, p- (hexadecylthio) phenol, p- (octadecylthio) phenol, p- (eicosylthio) phenol, p- (docosylthio) phenol, p- (tetracosylthio) phenol, p- (dodecyloxy) ) Phenol, p- (tetradecyloxy) phenol, p- (hexadecyloxy) phenol, p- (octadecyloxy) phenol, p- (eicosyloxy) phenol, p- (docosyloxy) phenol, p- (tetracosyloxy) phenol Ruoxy)
Phenol, p-dodecylcarbamoylphenol, p
-Tetradecylcarbamoylphenol, p-hexadecylcarbamoylphenol, p-octadecylcarbamoylphenol, p-eicosylcarbamoylphenol, p-docosylcarbamoylphenol, p-tetracosylcarbamoylphenol, hexadecyl gallate, octadecyl gallate Eicosyl gallate, docosyl gallate, tetracosyl gallate, N-dodecyl-p-hydroxycinnamic amide, N-tetradecyl-p-hydroxycinnamic amide, N-octadecyl-p-hydroxycinnamic acid Amides, N-docosyl-p-hydroxycinnamic amide, N-octacosyl-p-hydroxycinnamic amide,
4-hydroxytridecanoylaniline, 4-hydroxyheptadecanoylaniline, 4-hydroxynonadecanoylaniline, 3-hydroxynonadecanoylaniline, 4-hydroxydocosanoylaniline, 4-N-octadecylsulfonylaminophenol, 4- N-dodecylsulfonylaminophenol, N-4-hydroxyphenyl-N'-dodecylurea, N-4-hydroxyphenyl-N'-octadecylurea, N-4-hydroxyphenyl-N'-docosylurea and the like.

The reversible thermosensitive recording medium of the present invention basically contains a composition comprising the above-mentioned color developer and color former. The color former used in the present invention has an electron donating property, and is a colorless or light-colored dye precursor (leuco dye) per se, and is not particularly limited, and conventionally known compounds such as triphenylmethanephthalide compounds. , A fluoran compound, a phenothiazine compound, a leuco auramine compound, an indinophthalide compound, and the like. The color former is shown below.

[0028]

[Chemical 7]

However, R ₁₁ represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and R ₁₂ represents an alkyl group having 1 to 6 carbon atoms, a cyclohexyl group or an optionally substituted phenyl group. Examples of the substituent for the phenyl group include an alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and a halogen atom. R ₁₃ is hydrogen and has 1 carbon atom
2 represents an alkyl group, an alkoxy group or halogen. R ₁₄ represents hydrogen, a methyl group, halogen or an optionally substituted amino group. The substituent for the amino group is an alkyl group, an optionally substituted aryl group, an aralkyl group, or the like, and the substituent here is an alkyl group, a halogen, an alkoxy group, or the like. Specific examples of such a color former include the following compounds.

2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-
(Di-n-butylamino) fluorane, 2-anilino-
3-methyl-6- (Nn-propyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N
-Isopropyl-N-methylamino) fluoran, 2-
Anilino-3-methyl-6- (N-isobutyl-N-methylamino) fluoran, 2-anilino-3-methyl-
6- (Nn-amyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-sec-butyl-N-ethylamino) fluoran, 2-anilino-
3-methyl-6- (Nn-amyl-N-ethylamino) fluoran, 2-anilino-3-methyl-6- (N
-Iso-amyl-N-ethylamino) fluoran, 2
-Anilino-3-methyl-6- (Nn-propyl-N
-Isopropylamino) fluoran, 2-anilino-3
-Methyl-6- (N-cyclohexyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N
-Ethyl-p-toluidino) fluorane, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluorane, 2- (m-trichloromethylanilino) -3
-Methyl-6-diethylaminofluorane, 2- (m-
Trifluoromethylanilino) -3-methyl-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6- (N-cyclohexyl-N-
Methylamino) fluoran, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluoran, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino) Fluoran, 2- (N-
Methyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluoran, 2-anilino-
6- (Nn-hexyl-N-ethylamino) fluoran, 2- (o-chloroanilino) -6-diethylaminofluoran, 2- (o-bromoanilino) -6-diethylaminofluoran, 2- (o-chloroanilino ) -6
-Dibutylaminofluoran, 2- (o-fluoroanilino) -6-dibutylaminofluoran, 2- (m-trifluoromethylanilino) -6-diethylaminofluoran, 2- (p-acetylanilino) -6 − (N−n−
Amyl-Nn-butylamino) fluoran, 2-benzylamino-6- (N-ethyl-p-toluidino) fluoran, 2-benzylamino-6- (N-methyl-2,
4-dimethylanilino) fluoran, 2-benzylamino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-dibenzylamino-6- (N-methyl-
p-Toluidino) fluoran, 2-dibenzylamino-
6- (N-ethyl-p-toluidino) fluoran, 2-
(Di-p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethylamino) -6- (N-ethyl-p-toluidino) fluoran, 2-methylamino -6- (N-methylanilino) fluoran, 2-methylamino-6- (N-ethylanilino) fluoran, 2-methylamino-6- (N-
Propylanilino) fluoran, 2-ethylamino-6
-(N-methyl-p-toluidino) fluorane, 2-ethylamino-6- (N-ethyl-p-toluidino) fluorane, 2-methylamino-6- (N-methyl-2,4)
-Dimethylanilino) fluorane, 2-ethylamino-
6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2-dimethylamino-6- (N-ethylanilino) fluorane, 2-diethylamino-6 −
(N-methyl-p-toluidino) fluorane, 2-diethylamino-6- (N-ethyl-p-toluidino) fluorane, 2-dipropylamino-6- (N-methylanilino) fluorane, 2-dipropylamino-6 -(N-
Ethylanilino) fluoran, 2-amino-6- (N-
Methylanilino) fluorane, 2-amino-6- (N-
Ethylanilino) fluoran, 2-amino-6- (N-
Propylanilino) fluorane, 2-amino-6- (N
-Methyl-p-toluidino) fluorane, 2-amino-
6- (N-ethyl-p-toluidino) fluoran, 2-
Amino-6- (N-propyl-p-toluidino) fluorane, 2-amino-6- (N-methyl-p-ethylanilino) fluorane, 2-amino-6- (N-ethyl-p
-Ethylanilino) fluoran, 2-amino-6- (N
-Propyl-p-ethylanilino) fluorane, 2-amino-6- (N-methyl-2,4-dimethylanilino)
Fluorane, 2-amino-6- (N-ethyl-2,4-
Dimethylanilino) fluoran, 2-amino-6- (N
-Propyl-2,4-dimethylanilino) fluoran,
2-amino-6- (N-methyl-p-chloranilino)
Fluorane, 2-amino-6- (N-ethyl-p-chloranilino) fluorane, 2-amino-6- (N-propyl-p-chloranilino) fluorane, 2,3-dimethyl-6-dimethylaminofluorane, 3, -Methyl-6
-(N-ethyl-p-toluidino) fluorane, 2-chloro-6-diethylaminofluorane, 2-bromo-6
-Diethylaminofluorane, 2-chloro-6-dipropylaminofluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2-chloro-6- (N-ethyl- N
-Isoamylamino) fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-
3-chloro-6-diethylaminofluorane, 2- (o
-Chloroanilino) -3-chloro-6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluorane, 2
-(2,3-Dichloroanilino) -3-chloro-6-diethylaminofluorane, 1,2-benzo-6-diethylaminofluorane, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluorane 1,2-benzo-6-dibutylaminofluorane, 1,2-benzo-
6- (N-methyl-N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-p-toluidino) fluorane, and others.

Specific examples of other color formers preferably used in the present invention are as follows. 2-anilino-3-methyl-6- (N-2-ethoxypropyl-N-
Ethylamino) fluorane, 2- (p-chloroanilino) -6- (Nn-octylamino) fluorane, 2
-(P-chloranilino) -6- (Nn-palmitylamino) fluorane, 2- (p-chloranilino) -6
-(Di-n-octylamino) fluoran, 2-benzoylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (o-methoxybenzoylamino) -6
(N-methyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6-diethylaminofluoran, 2-dibenzylamino-4-methoxy-6- (N
-Methyl-p-toluidino) fluoran, 2-benzylamino-4-methyl-6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethylamino)-
4-methyl-6-diethylaminofluorane, 2- (p
-Toluidino) -3- (t-butyl) -6- (N-methyl-p-toluidino) fluoran, 2- (o-methoxycarbonylanilino) -6-diethylaminofluoran, 2-acetylamino-6- ( N-methyl-p-toluidino) fluoran, 3-diethylamino-6- (m-
Trifluoromethylanilino) fluorane, 4-methoxy-6- (N-ethyl-p-toluidino) fluorane, 2
-Ethoxyethylamino-3-chloro-6-dibutylaminofluorane, 2-dibenzylamino-4-chloro-
6- (N-ethyl-p-toluidino) fluoran, 2-
(Α-Phenylethylamino) -4-chloro-6-diethylaminofluorane, 2- (N-benzyl-p-trifluoromethylanilino) -4-chloro-6-diethylaminofluorane, 2-anilino-3- Methyl-6-pyrrolidinofluorane, 2-anilino-3-chloro-6-pyrrolidinofluorane, 2-anilino-3-methyl-6-
(N-ethyl-N-tetrahydrofurfurylamino) fluoran, 2-mesidino-4 ′, 5′-benzo-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6 Pyrrolidinofluoran,
2- (α-naphthylamino) -3,4-benzo-4′-
Bromo-6- (N-benzyl-N-cyclohexylamino) fluorane, 2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2- (p-acetylanilino) -6- (Nn -Amyl-N-n-butylamino) fluorane, 2-benzylamino-6- (N
-Ethyl-p-toluidino) fluorane, 2-benzylamino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N-ethyl-2,4-dimethylanilino) ) Fluoran, 2-dibenzylamino-6- (N-methyl-p-toluidino) fluorane, 2-dibenzylamino-6- (N-ethyl-)
p-toluidino) fluorane, 2- (di-p-methylbenzylamino) -6- (N-ethyl-p-toluidino)
Fluorane, 2- (α-phenylethylamino) -6-
(N-ethyl-p-toluidino) fluorane, 2-methylamino-6- (N-methylanilino) fluorane, 2
-Methylamino-6- (N-ethylanilino) fluorane, 2-methylamino-6- (N-propylanilino)
Fluoran, 2-ethylamino-6- (N-methyl-p
-Toluidino) fluorane, 2-ethylamino-6-
(N-ethyl-p-toluidino) fluorane, 2-methylamino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-ethylamino-6- (N-ethyl-2,4-dimethyl) Anilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2
-Dimethylamino-6- (N-ethylanilino) fluoran, 2-diethylamino-6- (N-methyl-p-toluidino) fluoran, 2-diethylamino-6- (N
-Ethyl-p-toluidino) fluoran, 2-dipropylamino-6- (N-methylanilino) fluoran, 2
-Dipropylamino-6- (N-ethylanilino) fluoran, 2-amino-6- (N-methylanilino) fluoran, 2-amino-6- (N-ethylanilino) fluoran, 2-amino-6- (N-propyl Anilino) fluoran, 2-amino-6- (N-methyl-p-toluidino) fluoran, 2-amino-6- (N-ethyl-p
-Toluidino) fluoran, 2-amino-6- (N-propyl-p-toluidino) fluoran, 2-amino-6
-(N-methyl-p-ethylanilino) fluoran, 2
-Amino-6- (N-ethyl-p-ethylanilino) fluoran, 2-amino-6- (N-propyl-p-ethylanilino) fluoran, 2-amino-6- (N-methyl-2,4-dimethylaniline) Rino) fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-propyl-2,4-
Dimethylanilino) fluoran, 2-amino-6- (N
-Methyl-p-chloroanilino) fluoran, 2-amino-6- (N-ethyl-p-chloroanilino) fluoran, 2-amino-6- (N-propyl-p-chloroanilino) fluoran, 2,3-dimethyl-6 -Dimethylaminofluoran, 3-methyl-6- (N-ethyl-p-
Toluidino) fluoran, 2-chloro-6-diethylaminofluoran, 2-bromo-6-diethylaminofluoran, 2-chloro-6-dipropylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 3-bromo -6-cyclohexylaminofluoran, 2-chloro-6- (N-ethyl-N-isoamylamino) fluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-chloro-6
-Diethylaminofluorane, 2- (o-chloroanilino) -3-chloro-6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluorane, 2- (2 , 3-Dichloroanilino) -3-chloro-6-diethylaminofluorane, 1,2-benzo-6-diethylaminofluorane, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluorane, 1, 2-benzo-6-dibutylaminofluorane, 1,2-benzo-6- (N-methyl-N-cyclohexylamino) fluorane, 1,2-
Benzo-6- (N-ethyl-p-toluidino) fluorane, etc.

Specific examples of other color formers preferably used in the present invention are as follows. 2-anilino-3-methyl-6- (N-2-ethoxypropyl-N-
Ethylamino) fluorane, 2- (p-chloroanilino) -6- (Nn-octylamino) fluorane, 2
-(P-chloranilino) -6- (Nn-palmitylamino) fluorane, 2- (p-chloranilino) -6
-(Di-n-octylamino) fluoran, 2-benzoylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (o-methoxybenzoylamino) -6
(N-methyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6-diethylaminofluoran, 2-dibenzylamino-4-methoxy-6- (N
-Methyl-p-toluidino) fluoran, 2-benzylamino-4-methyl-6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethylamino)-
4-methyl-6-diethylaminofluorane, 2- (p
-Toluidino) -3- (t-butyl) -6- (N-methyl-p-toluidino) fluoran, 2- (o-methoxycarbonylanilino) -6-diethylaminofluoran, 2-acetylamino-6- ( N-methyl-p-toluidino) fluoran, 3-diethylamino-6- (m-
Trifluoromethylanilino) fluorane, 4-methoxy-6- (N-ethyl-p-toluidino) fluorane, 2
-Ethoxyethylamino-3-chloro-6-dibutylaminofluorane, 2-dibenzylamino-4-chloro-
6- (N-ethyl-p-toluidino) fluoran, 2-
(Α-Phenylethylamino) -4-chloro-6-diethylaminofluorane, 2- (N-benzyl-p-trifluoromethylanilino) -4-chloro-6-diethylaminofluorane, 2-anilino-3- Methyl-6-pyrrolidinofluorane, 2-anilino-3-chloro-6-pyrrolidinofluorane, 2-anilino-3-methyl-6-
(N-ethyl-N-tetrahydrofurfurylamino) fluoran, 2-mesidino-4 ′, 5′-benzo-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6 Pyrrolidinofluoran,
2- (α-naphthylamino) -3,4-benzo-4′-
Bromo-6- (N-benzyl-N-cyclohexylamino) fluorane, 2-piperidino-6-diethylaminofluorane, 2-N-n-propyl-p-trifluoromethylanilino) -6-morpholinofluorane, 2-
(Di-Np-chlorophenyl-methylamino) -6-
Pyrrolidinofluoran, 2- (Nn-propyl-m-
Trifluoromethylanilino) -6-morpholinofluorane, 2- (di-Np-chlorophenyl-methylamino) -6-pyrrolidinofluorane, 2- (Nn-propyl-m-trifluoro) Methylanilino) -6-morpholinofluorane, 1,2-benzo-6- (N-ethyl-
Nn-octylamino) fluorane, 1,2-benzo-6-diallylaminofluorane, 1,2-benzo-6
-(N-Ethoxyethyl-N-ethylamino) fluorane, benzoleucomethylene blue, 2- [3,6-bis (diethylamino)]-6- (o-chloroanilino) xanthyl benzoate lactam, 2- [3,6- Bis (diethylamino)]-9- (o-chloroanilino) xanthyl benzoate lactam, 3,3-bis (p-dimethylanilino) -phthalide, 3,3-bis (p-dimethylanilino) -6-dimethylamino Phthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylanilino) -6-diethylaminophthalide, 3,3-bis (p-dimethylanilino) -6-chlorophthalide, 3,
3-bis (p-dibutylanilino) phthalide, 3- (2
-Methoxy-4-dimethylaminophenyl) -3- (2
-Hydroxy-4,5-dichlorophenyl) phthalide,
3- (2-hydroxy-4-dimethylaminophenyl)
-3- (2-methoxy-5-chlorophenyl) phthalide, 3- (2-hydroxy-4-dimethoxyanilino)
-3- (2-Methoxy-5-chlorophenyl) phthalide, 3- (2-hydroxy-4-dimethylanilino)-
3- (2-methoxy-5-nitrophenyl) phthalide,
3- (2-hydroxy-4-diethylanilino) -3-
(2-methoxy-5-tolyl) phthalide, 3- (2-methoxy-4-dimethylanilino) -3- (2-hydroxy-4-chloro-5-methoxyphenyl) phthalide,
3,6-bis (dimethylamino) fluorene spiro (9,3 ′)-6′-dimethylaminophthalide, 6′-
Chlor-8'-methoxy-benzoindolinose pyropyran, 6'-bromo-2'-methoxy-benzoindolinose pyropyran and the like.

The reversible thermosensitive recording medium of the present invention can form a relatively colored state and a relatively decolored state depending on the heating temperature and / or the cooling rate after heating. This basic coloring / decoloring phenomenon will be described. FIG. 1 shows the relationship between the color density of the composition and the temperature. Introduction gradually heated a composition in the decolorized state (A), a molten colored state occurs coloration at temperatures T ₁ begins to melt (B). When the color is rapidly cooled from the melted color development state (B), the temperature can be lowered to room temperature while maintaining the color development state, and a solid color development state (C) is obtained. Whether or not this color-developed state is obtained depends on the rate of temperature decrease from the molten state. In the case of slow cooling, decoloration occurs in the process of temperature decrease, and the same decolored state (A) or quenched color state (C) as at the beginning. A) is formed with a relatively lower concentration. On the other hand, rapidly cooled colored state (C) is again raised gradually and decoloration occurs with a color temperature lower than temperature T ₂ and (E from D), the same colorless state, including when the temperature decreases from which (A)
Return to The actual color development temperature and decolorization temperature vary depending on the combination of the color developer and color developer used, and can be selected according to the purpose. In addition, the density in the molten color development state and the color development density after quenching do not always match, and may differ.

The composition composed of the color developer and the color developer contained in the recording layer of the present invention is such that in the color development state (C) obtained by quenching from the molten state, the color development agent and the color development agent are brought into contact reaction between molecules. It is in a possibly mixed state, which often forms a solid state. This state is a state in which the color developer and the color forming agent aggregate to maintain the color development, and it is considered that the color formation is stabilized by the formation of the aggregate structure. On the other hand, the decolored state is a state where both are phase-separated. This state is a state in which molecules of at least one compound are aggregated to form a domain or crystallized, and it is considered that the color former and the developer are separated and stabilized by aggregation or crystallization. Can be In many cases, the present invention causes more complete decoloration due to phase separation of the two and crystallization of the color developer. In both the decolored state from the molten state by slow cooling and the decolored state by heating from the colored state shown in FIG. 1, the aggregation structure changes at this temperature, and phase separation and crystallization of the developer occur.

The formation of color recording on the reversible thermosensitive recording medium of the present invention is carried out by using a thermal head or the like to once heat it to a temperature at which it is melt-mixed and then quench it. There are two methods of decoloring: a method of gradually cooling from a heated state and a method of heating to a temperature slightly lower than the color development temperature. However, they are the same in that they both temporarily separate at a temperature at which they phase separate or at least one crystallizes. The quenching in the formation of a colored state is to prevent the phase separation or the crystallization temperature from being maintained. Here, the rapid cooling and the slow cooling are relative to one composition, and the boundary changes depending on the combination of the color former and the developer. The reversible thermosensitive recording medium of the present invention comprises a support and a recording layer containing the above composition as a main component. The support is paper, resin film, synthetic paper, metal foil, glass or a composite thereof, and may be any as long as it can hold the recording layer.

The recording layer may be of any type as long as the composition of the present invention is present. Generally, a state in which a color former and a developer are finely and uniformly dispersed in a binder resin is used. The color former and the developer may form particles individually, but more preferably form a dispersed state as composite particles. This can be achieved by melting or dissolving the color former and the developer once. To form such a recording layer, a liquid obtained by dispersing and dissolving each material in a solvent, or a liquid obtained by mixing and dispersing or dissolving each material in a solvent is applied to a support and dried. Done by The color former and the developer can be used by being encapsulated in microcapsules. In the reversible thermosensitive recording medium of the present invention, an additive for improving or controlling the coating characteristics and the coloring and decoloring characteristics of the recording layer can be used as necessary. These additives include, for example, dispersants, surfactant conductive agents, fillers, lubricants, antioxidants, light stabilizers, ultraviolet absorbers, color stabilizers, and decolorization accelerators.

Examples of the binder resin used for forming the recording layer include polyvinyl chloride, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, ethyl cellulose, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester. , Polyurethane, polycarbonate, polyacrylic acid ester, polymethacrylic acid ester, acrylic acid type copolymer, maleic acid type copolymer, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, starches and the like. The role of these binder resins is to maintain a state in which the materials of the composition are uniformly dispersed without bias due to the application of heat for recording and erasing. Therefore, it is preferable to use a resin having high heat resistance as the binder resin. For example, the binder resin may be cross-linked by heat, ultraviolet rays, electron beams, or the like.

The reversible thermosensitive recording medium of the present invention basically has the above-mentioned recording layer provided on a support, but in order to improve the characteristics as a recording medium, a protective layer, an adhesive layer,
An intermediate layer, an undercoat layer, a back coat layer and the like can be provided. In printing using a thermal head, the surface of the recording layer may be deformed due to heat and pressure, and so-called dents may be formed. In order to prevent this, it is preferable to provide a protective layer on the surface. For the protective layer, polyvinyl alcohol,
Besides styrene-maleic anhydride copolymer, carboxy-modified polyethylene, melamine-formaldehyde resin, urea-formaldehyde resin, UV curable resin and electron beam curable resin can be used. Further, the protective layer may contain additives such as an ultraviolet absorber.

An intermediate layer is provided between the recording layer and the protective layer for the purpose of improving the adhesiveness, preventing deterioration of the recording layer by coating the protective layer, and preventing migration of additives in the protective layer to the recording layer. Is also preferable. Also, a protective layer installed on the recording layer,
It is preferable to use a resin having low oxygen permeability for the intermediate layer. It is possible to prevent or reduce oxidation of the color former and the developer in the recording layer. Further, a heat insulating undercoat layer can be provided between the support and the recording layer in order to effectively utilize the applied heat. The heat insulating layer can be formed by applying organic or inorganic fine hollow particles using a binder resin. An undercoat layer may be provided for the purpose of improving the adhesion between the support and the recording layer and preventing the penetration of the recording layer material into the support.

For the intermediate layer and the undercoat layer, the same resin as the resin for the recording layer can be used. Also,
Fillers such as calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, kaolin and talc may be contained in the protective layer, the intermediate layer, the recording layer and the undercoat layer. In addition, a lubricant, a surfactant dispersant and the like can be contained. In order to form a color image using the reversible thermosensitive recording material of the present invention, it is sufficient that the color image is heated once above the color development temperature and then rapidly cooled. Specifically, for example, when the recording layer is heated for a short time by a thermal head or laser light, the recording layer is locally heated, so that the heat is immediately diffused, rapid cooling occurs, and the coloring state can be fixed. On the other hand, in order to erase the color, it may be heated and cooled for a relatively long time using an appropriate heat source, or may be temporarily heated to a temperature slightly lower than the coloring temperature. If the recording medium is heated for a long time, the entire temperature of the recording medium rises over a wide range, and the subsequent cooling is slowed down. As a heating method in this case, a heat roller, a heat stamp, hot air, or the like may be used, or heating may be performed for a long time using a thermal head.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. It goes without saying that the content of the present invention is not limited by the present embodiment because all the parts in this embodiment are parts by weight. Example 1 (Recording Layer) The following composition was ground and dispersed in a ball mill to 1 μm or less to prepare a recording layer forming liquid A liquid.

2-anilino-3-methyl-6- (N-methyl-p-triidino) fluorane: Dye 5.00 parts Docosylphosphonic acid: Developer 27.5 parts Vinyl chloride-vinyl acetate copolymer (Union Carbide: VYHH): Resin 118.6 parts 1,3-Dicyclohexyl-2- (2,5-dichlorophenyl) guanidine (DCPG) 0.13 parts Methyl ethyl ketone 160.7 parts Toluene 160.7 parts Resin / (dye + developer) = 3.65 Developer / dye = 5.50 Then, the recording layer forming liquid A is applied on a white PET film having a thickness of 100 μm using a wire bar to a thickness of about 8
It was coated so as to have a thickness of .mu.m, color-dried at 150.degree. C. for 1 minute, and then heat-treated at 80.degree. C. for 10 minutes to remove the color to form a reversible recording medium (a).

Example 2 (Recording Layer) The following composition was ground and dispersed in a ball mill to 1 μm or less to prepare a recording layer forming liquid B. 2-aniline-3-methyl-6- (N-ethyl-p-triidino) fluorane: dye 3.64 parts docosylphosphonic acid: developer 15.0 parts vinyl chloride-vinyl acetate copolymer (union car Bite: VYHH): resin 68.04 parts 1,3-dicyclohexyl-2- (2,5-dichlorophenyl) guanidine (DCPG) 0.13 parts methyl ethyl ketone 160.7 parts toluene 160.7 parts resin / ( (Dye + Developer) = 3.65 Developer / Dye = 4.12 Then, the recording layer forming liquid B is applied on a white PET film having a thickness of 100 μm using a wire bar to a thickness of about 8
It was coated so as to have a thickness of μm, color-dried at 150 ° C. for 1 minute, and then heat-treated at 80 ° C. for 10 minutes to erase the color, thereby forming a reversible recording medium (b).

Comparative Example 1 Resin 3 in the solution A in Example 1 was a vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide Co.).
The recording layer forming liquid C was formed in the same manner as in Example 1 except that the amount was 90.0 parts. As a result, resin / (dye +
(Developer) = 12.0 and developer / dye = 5.50. After that, the above-mentioned recording layer forming liquid C was applied onto a white PET film having a thickness of 100 μm using a wire bar so that the coating thickness would be about 8 μm, color-dried at 150 ° C. for 1 minute, and then at 80 ° C. for 10 minutes. Heat treatment was performed to erase the color, and a reversible recording medium (c) was formed.

Comparative Example 2 Resin 2 in Example 1 was mixed with resin: vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide Co.).
The recording layer forming liquid D was formed in the same manner as in Example 1 except that the amount was 5.0 parts. As a result, resin / (dye + developer) = 0.77 and developer / dye = 5.50. Thereafter, the recording layer forming liquid D was applied on a white PET film having a thickness of 100 μm by using a wire bar so as to have a coating thickness of about 8 μm, and color-dried at 150 ° C. for 1 minute,
Then, heat treatment was carried out at 80 ° C. for 10 minutes to carry out color erasing to form a reversible recording medium (d).

Comparative Example 3 The resin in the liquid A in Example 1 was 4: vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide).
20.0 parts, and a developer: docosylphosphonic acid 35.
The recording layer forming liquid E was formed in the same manner as in Example 1 except that the amount was 4 parts. As a result, resin / (dye + developer) = 10.4 and developer / dye = 7.08. Thereafter, the recording layer forming liquid E was applied onto a white PET film having a thickness of 100 μm using a wire bar so that the coating thickness was about 8 μm, and color development was performed at 150 ° C. for 1 minute,
Then, heat treatment was carried out at 80 ° C. for 10 minutes to carry out color erasing to form a reversible recording medium (e).

Comparative Example 4 Resin 1 in the liquid A in Example 1 was a vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide Co.).
50.0 parts and developer: docosylphosphonic acid 7.2
The recording layer forming liquid F liquid was formed in the same manner as in Example 1 except that the amount was 8 parts. As a result, the resin / (dye + developing agent) = 12.2 and the developer / dye = 1.46. Thereafter, the recording layer forming liquid F was applied on a white PET film having a thickness of 100 μm by using a wire bar so that the coating thickness was about 8 μm, and color-dried at 150 ° C. for 1 minute,
Then, heat treatment was carried out at 80 ° C. for 10 minutes to erase the color, thereby forming a reversible recording medium (f).

Comparative Example 5 Resin 2 in Example 1 was mixed with resin: vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide Co.).
5.0 parts and developer: docosylphosphonic acid 35.4
The recording layer forming liquid G liquid was formed in the same manner as in Example 1 except for the parts. As a result, resin / (dye + developer)
= 0.62 and the color developer / dye = 7.08. Thereafter, the recording layer forming liquid G was added to a white PE having a thickness of 100 μm.
Coating thickness of about 8μm using a wire bar on T film
The resulting reversible recording medium (g) was formed by coating and drying at 150 ° C for 1 minute, followed by heat treatment at 80 ° C for 10 minutes for erasing.

Comparative Example 6 Resin: A vinyl chloride-vinyl acetate copolymer (VYHH, manufactured by Union Carbide Co.) in Example 1 was adjusted to 8.00 parts, and a developer: docosylphosphonic acid was added to 7 parts. .2
The recording layer forming liquid H was formed in the same manner as in Example 1 except that the amount was 8 parts. As a result, resin / (dye + developer) = 0.65 and developer / dye = 1.46.

Thereafter, the above-mentioned recording layer forming liquid H liquid is applied to a thickness of 100.
A reversible recording medium was coated on a white PET film of μm with a wire bar to a coating thickness of about 8 μm, color-dried at 150 ° C. for 1 minute, and then heat-treated at 80 ° C. for 10 minutes to erase the color. (H) was formed. A silicon-modified UV resin is coated on the reversible recording media of Examples and Comparative Examples to form a coating film having a thickness of 2
It was coated so as to have a thickness of μm and an over layer was provided. Then 8
Printing was performed with an applied energy of 29 mj / mm ² by a printing apparatus having a dot / mm ² thermal head, and the following characteristics were measured with a Macbeth densitometer (RD914). (1) Repetitive characteristics Decoloring was carried out 20 times by placing it on an aluminum plate heated to 85 ° C for 30 seconds, and the image retention ratio of the color density of the reversible recording medium was examined.

[0051]

[Equation 1]

(2) Storage characteristics Print color density and heat resistance of the printed sample: heat resistance: image residual rate after storage at 50 ° C. for 24 hours, moisture resistance: temperature 40 ° C., humidity 90%, image residual rate after 24 hours storage. did. The results are shown in Table 1 for Examples and Tables 2 and 3 for Comparative Examples.

[0053]

[Equation 2]

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

The reversible thermosensitive composition of the present invention can be repeatedly formed into a stable color-developed state and a good decolored state.
A reversible thermosensitive recording medium using this can be formed by an easy operation of forming and erasing a high-contrast image. In addition, the color image is stable under normal use conditions, has high durability against repeated recording and erasure, and provides a highly practical rewritable recording medium.

[Brief description of drawings]

FIG. 1 shows the color development of the reversible thermosensitive coloring composition of the present invention.
It is a figure which shows a decoloring characteristic.

Claims (2)

[Claims] 1. A color developer and a color developer as main components,
In a reversible recording medium having a recording layer provided on a support, a recording layer capable of forming a color-developed state and a color-erased state by a difference in heating temperature and / or cooling temperature after heating, a dye as a color former and a developer. The reversible recording medium is characterized in that the binder resin is present in an amount of 3.0 parts by weight to 8.0 parts by weight per 1 part by weight. 2. The reversible thermosensitive recording medium according to claim 1, wherein the developing agent is present in an amount of from 2.5 parts by weight to 5.0 parts by weight with respect to 1 part by weight of the dye which is a coloring agent. Reversible recording medium.