JPH068623A - Reversible heat sensitive recording medium - Google Patents

Abstract

PURPOSE:To form clear recording images repeatedly for a long time by providing a protecting layer of a heat-proof film on the upper surface of a heat- sensitive recording layer of a reversible heat-sensitive recording medium and bonding the protecting layer and the heat-sensitive recording layer by means of a thermosetting resin. CONSTITUTION:A reversible heat-sensitive recording layer 2 is formed on the upper surface of a supporting body 1. As the reversible heat sensitive recording layer 2 is heated at high temperatures by a thermal head 4 at image forming processes (A)-(B), a colored image 3 is formed. On the other hand, when the recording layer 2 is heated at low temperatures by a heating roller 5 at image deleting processes (B)-(A), the colored image 3 is deleted. In this case, a protecting layer formed of a heat-proof film is added onto the upper surface of the heat-sensitive recording layer of the recording medium containing an electron- donating color-developing compound and an electron-accepting color-developing compound. The heat-sensitive recording layer is bonded with the protecting layer by means of a thermosetting resin.

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.

[0002]

2. Description of the Related Art Conventionally, heat-sensitive recording utilizing a color-forming reaction between an electron-donating color-forming compound (hereinafter also referred to as a color-developing agent) and an electron-accepting compound (hereinafter also referred to as a color-developing agent). The medium is widely known, and the output of electronic calculators, facsimiles, vending machines, printers of scientific measuring machines, C
Widely used in RT medical measurement printers. However, all of the conventional products are irreversible in color development, and it is not possible to alternately repeat color development and color erasing. On the other hand, according to the patent publication, some thermosensitive recording media utilizing a color forming reaction between a color forming agent and a color developing agent that reversibly perform color forming and color erasing have been proposed. For example, Japanese Patent Application Laid-Open No. 60-193691 discloses a color developer using a combination of gallic acid and phloroglucinol. The color-developing material obtained by thermally coloring this material is decolorized with water or steam. However, in the case of this heat-sensitive recording medium, there is a problem in that it is difficult to make it water resistant, and there is a problem in recording storability, and furthermore, there is a problem that the color erasing device for erasing the color developing body becomes large. JP-A-61-237684 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 development temperature and then rapidly cooling it. However, in the case of this recording medium, the coloring and erasing steps are complicated, and some color is still seen in the erasable body obtained by erasing the chromophore, and a colored image with good contrast is obtained. I can't.

JP-A-62-140881 and JP-A-62-14088
No. 138568 and JP-A No. 62-138556 disclose homogeneous compatible solutions of a color former, a developer and a carboxylic acid ester. This product shows a completely colored state at a low temperature and a completely decolored state at a high temperature, and can maintain the colored or decolored state at an intermediate temperature between them, and by printing with a thermal head on this medium, the colored background White characters (decolored body) can be recorded on (colored body). Therefore, in the case of this recording medium, since the image to be recorded is a negative image, its use is limited, and it is necessary to keep the image within a specific temperature range for storing the recorded image. JP-A-2-188294 and JP-A-2-188294
No. 188293, as a color developer, a salt of gallic acid and a higher aliphatic amine that reversibly develops and reduces a color, and bis (hydroxyphenyl) acetic acid or butyric acid and a higher aliphatic amine. The one with salt is shown. This product can be thermally colored in a specific temperature range and decolorized by heating at a higher temperature than that, but since its color developing action and color reducing action occur competitively, these actions are thermally suppressed. It is difficult to control and it is difficult to obtain good image contrast. As described above, the conventional reversible thermosensitive recording medium utilizing the reaction between the color former and the color developer has various problems and is still unsatisfactory.

The present inventors previously used a compound such as an organic phosphoric acid having a long-chain aliphatic group, a carboxyl compound, a phenol compound, and a hydroxyphosphonic acid as a color developer, and used this as a color former. By combining with a compound etc., the coloring and decoloring can be easily performed only by heating, and the coloring and decoloring states can be maintained at room temperature, and the decoloring temperature is the coloring temperature. In addition, a reversible thermochromic composition capable of repeatedly forming and erasing an image many times by temperature change, and a reversible thermosensitive recording medium containing the same in a recording layer have been proposed. This reversible thermosensitive recording medium does not cause problems such as a decrease in color density and defective erasing even when it is repeatedly used a number of times, and can be used a number of times that is unthinkable from the prior art. However, when performing high-speed recording, the specified thermal energy must be supplied in a short time, so the thermal head temperature inevitably rises and the degree of surface wear when high-speed recording is repeated many times. Is incomparably larger than the case where recording is performed several times at a low speed, so in order to fully utilize the advantages of the recording medium even under severe conditions such as high-speed recording, the recording layer is subject to heat and abrasion. It is necessary to install a protective layer to prevent damage from damage. In order to protect the recording layer under such a high temperature and high speed condition, the material used for the protective layer is preferably a material having high thermal and mechanical resistance, and the present inventor has a significantly higher resistance than the conventional protective layer. We proposed a protective layer formed of a large heat-resistant film (Japanese Patent Application No. 4-69139). However, when a heat-resistant film is pasted on the recording layer using a thermoplastic resin as an adhesive, the recorded image often loses its color over time, and a reversible thermosensitive recording medium using the heat-resistant film as a protective layer has not yet been completed. It cannot be said that it has reached the limit.

[0005]

SUMMARY OF THE INVENTION The present invention provides a reversible thermosensitive recording medium utilizing a reaction between a color former such as a fluorane compound and a developer having a long-chain aliphatic group, which causes color development failure or deterioration with time. It is an object of the present invention to provide a reversible thermosensitive recording medium that does not cause image deterioration and can form a clear recorded image repeatedly for a long period of time even under severe conditions such as high-speed recording. An object of the present invention is to provide a reversible thermosensitive recording medium having a protective film as a protective layer, in which the recorded image does not fade over time.

[0006]

The present inventor has completed the present invention as a result of intensive studies to solve the above-mentioned problems. That is, according to the present invention, a thermosensitive recording layer containing an electron-donating color-forming compound and an electron-accepting compound is provided on a support, and a color-recorded state is formed by heating and melting, and the temperature is lower than the color-recording temperature. In a reversible thermosensitive recording medium that forms a decolored state in which recording disappears by heating at a temperature,
Provided is a reversible thermosensitive recording medium comprising a protective layer made of a heat-resistant film on the upper surface of the thermosensitive recording layer and bonding the thermosensitive recording layer and the protective layer with a thermosetting resin.

The heat-sensitive recording medium of the present invention instantly develops color upon heating, and the state of color development is stable even at room temperature. On the other hand, the reversible thermosensitive recording layer in the color-developed state can be instantly decolored by heating below the color-developing temperature, and the decolorized state is stable even at room temperature.
The principle of color development and color erasure of the reversible thermosensitive recording medium of the present invention, that is, image formation and image erasure will be described with reference to the graph shown in FIG. The vertical axis of the graph represents the color density and the horizontal axis represents the temperature, and the solid line 1 represents the image forming process by heating.
A broken line 3 shows an image erasing process by heating.
A is the density in the completely erased state, B is the density in the completely colored state when heated to a temperature of T ₁ or higher,
C is the density at the temperature of T ₀ or less in the completely colored state, and D is the density when the image is erased by heating at the temperature between T _{0 and} T ₁ . The reversible thermosensitive recording medium of the present invention is in a colorless state (A) at a temperature of T ₀ or lower. To perform recording, heating with a thermal head or the like to a temperature of T ₁ or higher is performed, and color development (B) is performed to form a recorded image. Even if the recorded image is returned to the temperature of T ₀ or less according to the solid line 2, the state (C) is maintained as it is, and the recording memory property is not lost. Next, in order to erase the recorded image, the formed recorded image may be heated to a temperature between T _{0 and} T _{1, which} is lower than the coloring temperature, and the state becomes colorless (D). This state is maintained as it is even if the temperature is returned to T ₀ or lower (A). That is, the process of forming the recorded image reaches C by the path of the solid line ABC and the recording is held. During the process of erasing the recorded image, the erased state is maintained up to A by the path of the broken line CDA. The behavioral characteristics of formation and erasure of the recorded image are reversible and can be repeated many times.

FIG. 2 is an explanatory view showing an example of image formation and image erasure, in which 1 is a support and 2 is a reversible thermosensitive recording layer. The image forming steps (A) → (B) are achieved by recording and printing at a temperature of T ₁ or higher in FIG. 1 by a heat source for image formation, for example, the thermal head 4. Next, the image erasing step (B) → (A) is achieved by heating the image erasing heat source, for example, the heating roller 5 to a temperature between T _{0 and} T ₁ . In FIG. 2, 3 indicates a color image.
The reversible thermosensitive recording medium of the present invention contains a color former and a developer as essential components. Then, the color development of the reversible thermosensitive recording medium of the present invention is performed by a color former composition formed by eutectic reaction between a developer and a color former constituting the reversible thermosensitive recording layer by heating,
It is obtained by cooling to room temperature. Since this color-forming material composition has a decoloring temperature region on the lower temperature side than the melting temperature, it is generally preferable to perform rapid cooling in order to cool from the melt-colored state to room temperature while maintaining the color development. When gradually cooled, some color disappears when passing through the color-erasing temperature range, and the density often decreases.

It is considered that in the color former composition, the molecules of the color former and the developer interact with each other to open the lactone ring of the color former to develop a color. The composition in the melted state and the rapidly cooled state contains, in addition to the chromophore molecule, the developer molecule and the chromophore molecule which are not directly involved in the formation of the chromophore. In the reversible thermosensitive recording medium of the present invention, the color-forming material composition at room temperature is in a solidified state due to the cohesive force between these molecules. Further, although the aggregate structure of the color former composition shows some regularity, it may be very regular or not very regular. This depends on the combination and amount ratio of the color developer and the color developer or the cooling conditions. The formation of such an aggregate structure is basically the long-chain structure part of the developer molecule forming the chromophore and the long-chain structure part of the excess developer molecule not forming the chromophore. It is presumed that the cohesive force acting between the parts mainly acts. The formation of such an aggregated structure is related to the decoloring phenomenon of the color former composition.

The color-forming material composition can be decolored by heating its color-developing state to a specific temperature range.
In this decoloring process, the aggregate structure of the color-developed state changes, and eventually the developer molecules are separated and crystallized from the color-forming composition to form crystals of the developer alone, resulting in a stable decolored state. X
Confirmed by lines. As described above, in the reversible thermosensitive recording medium of the present invention, it is clear that the long-chain portion of the color developer plays a large role in the formation of the color-developed state and the decoloring process thereof. This is a characteristic of the color former composition formed on the thermosensitive recording medium. Therefore, it has been confirmed that the decolorization temperature can be controlled by the length of the long chain portion of the color developer, and that the longer the chain length, the higher the color development and decolorization temperature shifts. This is because the aggregation and motility of the developer molecule change depending on the length of the long chain portion.

The color-forming composition which constitutes the reversible thermosensitive recording layer of the present invention is basically a composition in which the above-mentioned color developer having a long chain structure and the color-developing agent are combined, and In contrast there are preferred color formers. The combination of the color-developing agent and the color-developing agent used in this color-forming composition is a decoloring agent that occurs when a composition in a color-developed state obtained by heating both of them to a temperature lower than the melting temperature is heated. It is appropriately selected depending on the easiness, that is, the decoloring property and the characteristics such as the color tone of the coloring state. Among them, the decoloring property can be judged by the presence or absence of an exothermic peak appearing in the temperature rising process in the differential thermal analysis (DTA) or the differential scanning calorimetry (DSC) of the composition in the colored state obtained by the combination. This exothermic peak corresponds to the decoloring phenomenon that characterizes the present invention, and serves as a criterion for selecting a combination having a good decoloring property.
In the reversible thermosensitive recording medium of the present invention, the third substance may be present in the reversible thermosensitive recording layer, and for example, the reversible decoloring behavior can be maintained even when a polymer compound is present.

In the reversible thermosensitive recording medium of the present invention, the long-chain developer used in combination with the color former basically has a structure showing a color-developing ability capable of developing the color in the molecule, It is a compound that also has a long aliphatic chain structure portion that controls the cohesive force between molecules, and is an organic phosphoric acid compound, an aliphatic carboxylic acid compound, or a phenol compound having an aliphatic group having 12 or more carbon atoms, or 10 to 10 carbon atoms. 1
It is a metal salt of mercaptoacetic acid having an aliphatic group of 8. The aliphatic group includes a linear or branched alkyl group and alkenyl group, and may have a substituent such as halogen, an alkoxy group and an ester group.

As the organic phosphoric acid compound, a compound represented by the following general formula (1) is used. _{R 1 -PO (OH) 2 (} 1) ( provided that, R ₁ represents a number of 12 or more aliphatic group having a carbon)
Specific examples of the organic phosphoric acid compound represented by the general formula (1) include the following. Dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid, hexacosylphosphonic acid, octacosylphosphonic acid and the like.

As the aliphatic carboxylic acid compound, α-hydroxy fatty acids represented by the following general formula (2) are used. R ₂ —CH (OH) —COOH (2) (wherein 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 the following. α-hydroxydodecanoic acid, α-hydroxytetradecanoic acid, α-hydroxyhexadecanoic acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid,
α-Hydroxyeicosanoic acid, α-hydroxydocosanoic 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 used. Specific examples of such a compound include the followings. 2-chlorooctadecanoic acid, heptadecaflornonadecanoic acid, 2-bromohexadecanoic acid, 2-bromoheptadecanoic acid, 2-bromooctadecanoic acid, 2-bromoeicosanoic acid, 2-bromodocosanoic acid, 2-bromotetracosanoic acid , 3-bromooctadecanoic acid, 3-bromoeicosanoic acid, 2,3-dibromooctadecanoic acid, 2-flordodecanoic acid, 2-fluorotetradecanoic acid, 2-fluorohexadecanoic acid, 2-fluorooctadecanoic acid, 2-fluoroeicosane Acid, 2-flordocosanoic 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 a carbon number of 12 or more in the carbon chain, and at least the α-, β-, or γ-position carbon 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 (3) is also used. (However, R ₃ represents an aliphatic group having 12 or more carbon atoms,
X represents an oxygen atom or a sulfur atom, and n is 1 or 2
And Xn may be a —SO ₂ — group) Specific examples of the dibasic acid represented by the general formula (3) include the following. Dodecylmalic acid, tetradecylmalic acid, hexadecylmalic acid, octadecylmalic acid, eicosylmalic acid, docosylmalic acid, tetracosylmalic acid, dodecylthiomalic acid, tetradecylthiomalic acid, hexadecylthiomalic acid,
Octadecyl thiomalic acid, eicosyl thiomalic acid,
Docosylthiomalic acid, tetracosylthiomalic acid, dodecyldithiomalic acid, tetradecyldithiomalic acid,
Hexadecyldithiomalic acid, octadecyldithiomalic acid, eicosyldithiomalic acid, docosyldithiomalic acid, tetracosyldithiomalic acid, dodecylsulfone butanedioic acid, tetradecylsulfone butanedioic acid, hexadecylsulfone butanedioic acid, Octadecyl sulfone butanedioic acid, eicosyl sulfone butanedioic acid, docosyl sulfone butanedioic acid and the like.

As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (4) is also used. (However, R ₄ , R ₅ , and R ₆ represent hydrogen or an aliphatic group, at least one of which is an aliphatic group having 12 or more carbon atoms.) Specific examples of the dibasic acid represented by the general formula (4) Examples include, for example: Dodecyl butanedioic acid, tridecyl butanedioic acid, tetradecyl butanedioic acid, pentadecyl butanedioic acid, octadecyl butanedioic acid, eicosyl butanedioic acid, docosyl butanedioic acid,
2,3-dihexadecylbutanedioic acid, 2,3-dioctadecylbutanedioic acid, 2-methyl-3-dodecylbutanedioic acid, 2-methyl-3-tetradecylbutanedioic acid, 2-methyl-3- Hexadecyl butanedioic acid, 2-ethyl-3-
Dodecyl butanedioic acid, 2-propyl-3-dodecyl butanedioic acid, 2-octyl-3-hexadecyl butanedioic acid,
2-tetradecyl-3-octadecyl butanedioic acid and the like.

As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (5) is also used. (However, R ₇ and R ₈ represent hydrogen or an aliphatic group, and at least one of them is an aliphatic group having 12 or more carbon atoms.) Specific examples of the dibasic acid represented by the general formula (5) are as follows. , For example: Dodecylmalonic acid, tetradecylmalonic acid, hexadecylmalonic acid, octadecylmalonic acid, eicosylmalonic acid, docosylmalonic acid, tetracosylmalonic acid, didodecylmalonic acid,
Ditetradecylmalonic acid, dihexadecylmalonic acid, dioctadecylmalonic acid, dieicosylmalonic acid, didocosylmalonic acid, methyloctadecylmalonic acid, methyleicosylmalonic acid, methyldocosylmalonic acid, methyltetracosylmalonic 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. (However, R ₉ represents an aliphatic group having 12 or more carbon atoms,
n represents 0 or 1, m represents 1, 2 or 3, m is 2 or 3 when n is 0, and m is 1 or 2 when n is 1) Specific examples of the dibasic acid represented by) include the following. 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 can also be used. Specific examples thereof include the following.

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

[Chemical 1] (However, Y is -S-, -O-, -CONH-, or-
Represents COO-, 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 followings. p- (dodecylthio) phenol, p- (tetradecylthio) phenol, p- (hexadecylthio) phenol, p- (octadecylthio) phenol, p- (eicosylthio) phenol, p- (docosylthio) phenol, p- (tetracosyl) Ruthio) phenol, p- (dodecyloxy)
Phenol, p- (tetradecyloxy) phenol,
p- (hexadecyloxy) phenol, p- (octadecyloxy) phenol, p- (eicosyloxy)
Phenol, p- (docosyloxy) phenol, p-
(Tetracosyloxy) phenol, p-dodecylcarbamoylphenol, p-tetradecylcarbamoylphenol, p-hexadecylcarbamoylphenol,
p-octadecylcarbamoylphenol, p-eicosylcarbamoylphenol, p-docosylcarbamoylphenol, p-tetracosylcarbamoylphenol, hexadecyl gallate, octadecyl gallate, eicosyl gallate, docosyl gallate, Gallic acid tetracosyl ester etc.

As the organic phosphoric acid compound, the following general formula (8)
It is also possible to use an α-hydroxyalkylphosphonic acid represented by (However, R ₁₁ is an aliphatic group having ₁₁ to 29 carbon atoms)
Specific examples of the α-hydroxyalkylphosphonic acid represented by the general formula (8) include α-hydroxydodecylphosphonic acid, α-hydroxytetradecylphosphonic acid, α-
Examples thereof include hydroxyhexadecylphosphonic acid, α-hydroxyoctadecylphosphonic acid, α-hydroxyeicosylphosphonic acid, α-hydroxydocosylphosphonic acid, and α-hydroxytetracosylphosphonic acid.

As the metal salt of mercaptoacetic acid, a metal salt of alkyl or alkenyl mercaptoacetic acid represented by the general formula (9) is used. _{(R 12 -S-CH 2 -COO} ) 2 M (9) ( provided that, R ₁₂ represents an aliphatic group having from 10 to 18 carbon atoms, M represents tin, magnesium, zinc or copper) formula (9 Specific examples of the mercaptoacetic acid metal salt represented by the formula (1) include the following. Decyl mercapto acetate tin salt, dodecyl mercapto acetate tin salt, tetradecyl mercapto acetate tin salt, hexadecyl mercapto acetate tin salt, octadecyl mercapto acetate tin salt,
Decyl mercapto acetic acid magnesium salt, dodecyl mercapto acetic acid magnesium salt, tetradecyl mercapto acetic acid magnesium salt, hexadecyl mercapto acetic acid magnesium salt, octadecyl mercapto acetic acid magnesium salt,
Decyl mercapto acetic acid zinc salt, dodecyl mercapto acetic acid zinc salt, tetradecyl mercapto acetic acid zinc salt, hexadecyl mercapto acetic acid zinc salt, octadecyl mercapto acetic acid zinc salt, decyl mercapto acetic acid copper salt, dodecyl mercapto acetic acid copper salt, tetradecyl mercapto acetic acid copper salt , Hexadecylmercaptoacetic acid copper salt, octadecylmercaptoacetic acid copper salt and the like.

The color-forming composition formed in the reversible thermosensitive recording layer of the present invention is basically formed by combining a color-developing agent with the color-developing agent. The color-forming agent used in the present invention is one that exhibits an electron-donating property, and is itself a colorless or light-colored dye precursor, and is not particularly limited, and conventionally known ones such as triphenylmethanephthalide compound and fluorane compound. , Phenothiazine compounds, leuco auramine compounds, indinophthalide compounds and the like are used. Specific examples of the color former are shown below. As a preferred color former used in the present invention, there is a fluoran compound represented by the following general formula (10).

[Chemical 2] (Wherein, R ₁₃ represents a hydrogen atom, an alkyl group, an allyl group, a cyclic alkyl group, or an alkoxyalkyl group, R ₁₄
Represents an alkyl group, a cyclic alkyl group, an allyl group, an alkoxyalkyl group, or an optionally substituted phenyl group. X represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, an alkoxyalkyl group, or a halogen atom. Y represents a lower alkyl group, an amino group, a substituted amino group, a cyano group, or a halogen atom. )

Specific examples of the compound represented by the general formula (10) include the following compounds. 2-anilino-3-methyl-6- (Nn-hexyl-N-iso-amylamino) fluorane, 2-anilino-3-methyl-6-
(Di-n-hexylamino) fluorane, 2-anilino-3-methyl-6- (di-n-amylamino) fluorane, 2-anilino-3-methyl-6- (di-n-octylamino) fluorane, 2 -Anilino-3-methyl-6
-(Di-n-butylamino) fluorane, 2-anilino-3-methyl-6- (N-isopropyl-N-methylamino) fluorane, 2-anilino-3-methyl-6-
(Nn-octyl-N-ethylamino) fluorane,
2-anilino-3-methyl-6- (Nn-octyl-
N-iso-propylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-Nn-propylamino) fluorane, 2-anilino-3-methyl-
6- (Nn-amyl-Nn-butylamino) fluorane, 2-anilino-3-methyl-6- (Nn-amyl-N-ethylamino) fluorane, 2-anilino-3
-Methyl-6- (N-n-amyl-N-methylamino)
Fluoran, 2-anilino-3-methyl-6- (N-i
so-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (Nn-) Butyl-N-n-propylamino) fluorane, 2-anilino-3-methyl-6- (N
-Ethyl-N-sec-butylamino) fluorane, 2
-Anilino-3-methyl-6- (Nn-butyl-N-
iso-propylamino) fluorane, 2-anilino-
3-Methyl-6- (Nn-butyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (N
-Isobutyl-N-methylamino) fluorane.

2-anilino-3-methyl-6- (N-cyclohexyl-Nn-tetradecylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-Nn-dodecylamino) Fluoran, 2-anilino-3-methyl-6- (N-cyclohexyl-Nn
-Decylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-Nn-octylamino) fluorane, 2-anilino-3-methyl-6- (N
-Cyclohexyl-Nn-hexylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-Nn-amylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-) N-is
o-amylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-Nn-butylamino) fluorane, 2-anilino-3-methyl-6- (N
-Cyclohexyl-Nn-propylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-N-ethylamino) fluorane, 2-anilino-
3-Methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2-anilino-3-methyl-6-
(Dicyclohexylethylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexylethyl-Nn-hexylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexylethyl-N-
n-amylamino) fluorane, 2-anilino-3-methyl-6- (dicyclohexylmethylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexylmethyl-Nn-hexylamino) fluorane, 2
-Anilino-3-methyl-6- (N-cyclohexylmethyl-Nn-amylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexylmethyl-N
-N-butylamino) fluorane, 2-anilino-3-
Methyl-6- (N-cyclohexylmethyl-N-cyclohexylamino) fluorane.

2-anilino-3-methyl-6- (diallylamino) fluorane, 2-anilino-3-methyl-6
-(Nn-octyl-N-allylamino) fluorane, 2-anilino-3-methyl-6- (Nn-hexyl-N-allylamino) fluorane, 2-anilino-3
-Methyl-6- (Nn-amyl-N-allylamino)
Fluorane, 2-anilino-3-methyl-6- (N-ethyl-N-allylamino) fluorane, 2-anilino-
3-Methyl-6- (N-2-ethoxypropyl-N-ethylamino) fluorane, 2-anilino-3-methyl-
6- (diethoxyethylamino) fluorane, 2-anilino-3-methyl-6- (N-ethoxyethyl-Nn)
-Hexylamino) fluorane, 2-anilino-3-methyl-6- (N-ethoxyethyl-Nn-amylamino) fluorane, 2-anilino-3-methyl-6- (N
-Ethoxyethyl-N-iso-amylamino) fluorane, 2-anilino-3-methyl-6- (N-ethoxyethyl-Nn-butylamino) fluorane, 2-anilino-3-methyl-6- (N- Ethoxyethyl-N-ethylamino) fluorane, 2-anilino-3-methyl-
6- (N-ethoxymethyl-Nn-hexylamino)
Fluorane, 2-anilino-3-methyl-6- (N-ethoxymethyl-Nn-amylamino) fluorane, 2
-Anilino-3-methyl-6- (N-ethoxymethyl-
N-iso-amylamino) fluorane, 2-anilino-3-methyl-6- (Nn-hexadecylamino) fluorane, 2-anilino-3-methyl-6- (Nn-)
Octylamino) fluorane, 2-anilino-3-methyl-6- (Nn-hexylamino) fluorane, 2-
Anilino-3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-anilino-3-methyl-6-
(N-methyl-p-toluidino) fluorane,

2-anilino-3-methoxy-6- (di-
n-hexylamino) fluorane, 2-anilino-3-
Methoxy-6- (di-n-amylamino) fluorane,
2-anilino-3-methoxy-6- (Nn-hexyl-N-iso-amylamino) fluorane, 2-anilino-3-methoxy-6- (N-cyclohexyl-Nn
-Hexylamino) fluorane, 2-anilino-3-ethoxy-6- (di-n-amylamino) fluorane, 2
-Anilino-3-ethoxy-6- (di-n-butylamino) fluorane, 2-anilino-3-ethoxy-6-diethylaminofluorane, 2-anilino-3-ethoxy-6- (N-cyclohexyl-N- n-hexylamino) fluorane, 2-anilino-3-ethoxy-6-
(N-cyclohexyl-Nn-amylamino) fluorane, 2-anilino-3-ethoxyethyl-6- (di-
n-amylamino) fluorane, 2-anilino-3-ethoxyethyl-6- (di-n-butylamino) fluorane, 2-anilino-3-ethoxyethyl-6-diethylaminofluorane, 2-anilino-3-ethoxymethyl -6- (Di-n-butylamino) fluorane, 2-anilino-3-ethoxymethyl-6- (N-cyclohexyl-Nn-hexylamino) fluorane, 2-anilino-3-ethoxymethyl-6- ( Di-n-amylamino)
Fluoran, 2-anilino-3-methoxymethyl-6-
(N-cyclohexyl-Nn-hexylamino) fluorane, 2-benzylamino-3-methyl-6- (di-
n-butylamino) fluorane, 2-benzylamino-
3-methyl-6- (di-n-amylamino) fluorane, 2-benzylamino-3-methyl-6- (N-cyclohexyl-Nn-hexylamino) fluorane, 2
-(M-Trichloromethylanilino) -3-methyl-6
-Diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-
Methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2- (2,4-dimethylanilino)-
3-Methyl-6- (Nn-hexyl-N-iso-amylamino) fluorane, 2- (2,4-dimethylanilino) -3-methyl-6- (di-n-hexylamino)
Fluoran, 2- (2,4-dimethylanilino) -3-
Methyl-6- (di-n-amylamino) fluorane, 2
-(2,4-Dimethylanilino) -3-methyl-6-
(Di-n-butylamino) fluorane, 2- (2,4-
Dimethylanilino) -3-methyl-6-diethylaminofluorane, 2- (N-ethyl-p-toluidino) -3
-Methyl-6- (N-ethylanilino) fluorane, 2
-(N-methyl-p-toluidino) -3-methyl-6-
(N-propyl-p-toluidino) fluorane,

2-anilino-6- (di-n-hexylamino) fluorane, 2-anilino-6- (Nn-hexyl-N-iso-amylamino) fluorane, 2-anilino-6- (di-n) -Amylamino) fluoran, 2
-Anilino-6-diethylaminofluorane, 2-anilino-6- (Nn-hexyl-N-ethylamino) fluorane, 2-anilino-6- (N-cyclohexyl-
N-n-hexylamino) fluorane, 2-anilino-
6- (N-cyclohexyl-Nn-amylamino) fluorane, 2-anilino-6- (N-cyclohexyl-
N-methylamino) fluorane, 2-anilino-6-
(Diethoxyethylamino) fluorane, 2-anilino-6- (N-ethoxyethyl-N-iso-amylamino) fluorane, 2-anilino-6- (N-ethoxyethyl-Nn-amylamino) fluorane, 2- Anilino-6- (N-ethoxyethyl-Nn-butylamino) fluorane, 2-anilino-6- (Nn-octylamino) fluorane, 2-anilino-6- (Nn-)
Hexylamino) fluorane, 2-anilino-6- (N
-N-amylamino) fluorane, 2- (N-methylanilino) -6- (N-ethyl-p-toluidino) fluorane, 2- (o-chloroanilino) -6-diethylaminofluorane, 2- (o-bromoanilino)- 6-diethylaminofluorane, 2- (o-chloroanilino)-
6-dibutylaminofluorane, 2- (o-fluoroanilino) -6-dibutylaminofluorane, 2- (p-chloroanilino) -6- (Nn-octylamino) fluorane, 2- (p-chloranilino)- 6- (N-n-
Palmitylamino) fluorane, 2- (p-chloroanilino) -6- (di-n-octylamino) fluorane,
2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2- (p-acetylanilino) -6
-Diethylaminofluorane, 2- (p-acetylanilino) -6- (Nn-hexyl-N-iso-hexylamino) fluorane, 2- (p-acetylanilino)
-6- (di-n-hexylamino) fluorane, 2-
(P-Acetylanilino) -6- (Nn-hexyl-
N-n-amylamino) fluorane, 2- (p-acetylanilino) -6- (di-n-amylamino) fluorane, 2- (p-acetylanilino) -6- (Nn-amyl-N-) n-butylamino) fluorane, 2- (p-
Acetylanilino) -6- (N-cyclohexyl-N-
n-hexylamino) fluorane, 2- (p-acetylanilino) -6- (N-ethoxyethyl-N-iso-
Amylamino) fluorane, 2- (p-acetylanilino) -6- (N-ethoxyethyl-Nn-amylamino) 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) fluorane, 2-benzoylamino-6- (N-ethyl-p-toluidino) fluorane, 2
-(O-Methoxybenzoylamino) -6- (N-methyl-p-toluidino) fluorane, 2-dibenzylamino-6- (di-n-butylamino) fluorane, 2-dibenzylamino-6- (di -N-amylamino) fluorane, 2-dibenzylamino-6- (di-n-hexylamino) fluorane, 2-dibenzylamino-6- (N
-N-hexyl-N-iso-amylamino) fluorane, 2-dibenzylamino-6- (di-n-propylamino) fluorane, 2-dibenzylamino-6- (N-
Cyclohexyl-N-n-amylamino) fluorane,
2-dibenzylamino-6- (N-cyclohexyl-N
-N-hexylamino) fluorane, 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-dibenzylamino-4-methyl-6-diethylaminofluorane, 2-dibenzylamino-4-methyl-6- ( Di-n-propylamino) fluorane, 2-
Dibenzylamino-4-methyl-6- (di-n-butylamino) fluorane, 2-dibenzylamino-4-methyl-6- (di-n-amylamino) fluorane, 2-dibenzylamino-4-methoxy -6- (N-methyl-P
-Toluidino) fluorane, 2-benzylamino-4-
Methyl-6- (N-ethyl-P-toluidino) fluorane, 2- (α-phenylethylamino) -4-methyl-
6-Diethylaminofluorane, 2- (p-toluidino) -3- (t-butyl) -6- (N-methyl-p-toluidino) fluorane, 2- (α-phenylethylamino) -6- (N- Ethyl-p-toluidino) fluorane, 2- (o-methoxycarbonylanilino) -6-diethylaminofluorane,

2-Methylamino-6- (N-methylanilino) fluorane, 2-methylamino-6- (N-ethylanilino) fluorane, 2-methylamino-6- (N
-Propylanilino) fluorane, 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) fluorane, 2-acetylamino-
3-Methyl-6-diethylaminofluorane, 2-acetylamino-3-methyl-6- (di-n-butylamino) fluorane, 2-acetylamino-3-methyl-6
-(Di-n-amylamino) fluorane, 2-acetylamino-3-methyl-6- (di-n-hexylamino)
Fluoran, 2-acetylamino-6- (N-methyl-
p-toluizino) fluoran,

2-amino-6-diethylaminofluorane, 2-amino-6- (di-n-butylamino) fluorane, 2-amino-6- (di-n-amylamino) fluorane, 2-amino-6- (Di-n-hexylamino)
Fluoran, 2-amino-6- (N-cyclohexyl-
N-n-amylamino) fluorane, 2-amino-6-
(N-methylanilino) fluorane, 2-amino-6-
(N-ethylanilino) fluorane, 2-amino-6-
(N-propylanilino) fluorane, 2-amino-6
-(N-methyl-p-toluidino) fluorane, 2-amino-6- (N-ethyl-p-toluidino) fluorane, 2-amino-6- (N-propyl-p-toluidino) fluorane, 2-amino- 6- (N-methyl-p-
Ethylanilino) fluorane, 2-amino-6- (N-
Ethyl-p-ethylanilino) fluorane, 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) fluorane, 2-amino-6- (N-propyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-methyl-p -Chloranilino) fluorane, 2-amino-6- (N-ethyl-p-chloroanilino) fluorane, 2-amino-6-
(N-propyl-p-chloroanilino) fluorane,
2-Amino-3-methyl-6-diethylaminofluorane, 2-amino-3-methyl-6- (di-n-butylamino) fluorane, 2-amino-3-methyl-6- (di-n-amylamino) ) Fluoran, 2-amino-3-methyl-6- (di-n-hexylamino) fluoran, 2
-Amino-3-methoxy-6- (di-n-butylamino) fluorane, 2-amino-3-methoxy-6- (di-n-amylamino) fluorane, 2-amino-3-methoxy-6- (di -N-hexylamino) fluorane,

1,3-Dimethyl-6-diethylaminofluorane, 1,3-dimethyl-6- (di-n-butylamino) fluorane, 1,3-dimethyl-6- (di-n-)
Amylamino) fluorane, 1,3-dimethyl-6-
(Di-n-hexylamino) fluorane, 1,3-dimethyl-6- (N-cyclohexyl-Nn-butylamino) fluorane, 2,3-dimethyl-6-dimethylaminofluorane, 2-methyl-6 -Dimethylaminofluorane, 2-methyl-6-diethylaminofluorane, 2
-Methyl-6- (di-n-propylamino) fluorane, 2-methyl-6- (di-n-butylamino) fluorane, 2-methyl-6- (di-n-amylamino) fluorane, 2-methyl- 6- (di-n-hexylamino)
Fluoran, 2-methyl-6- (N-cyclohexyl-
N-n-amylamino) fluorane, 2-methyl-6-
(N-cyclohexyl-N-methylamino) fluorane, 3-diethylamino-6- (m-trifluoromethylanilino) fluorane, 3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-methyl- 6- (N
-Ethyl-p-toluidino) fluorane, 4-methoxy-6- (N-ethyl-p-toluidino) fluorane, 2
-Cyano-6-diethylaminofluorane, 2-cyano-6- (di-n-butylamino) fluorane, 2-cyano-6- (di-n-amylamino) fluorane, 2-cyano-6- (di-n -Hexylamino) fluorane, 2
-Cyano-6- (N-cyclohexyl-Nn-hexylamino) fluorane, 2-cyano-6- (N-cyclohexyl-Nn-decylamino) fluorane.

2-chloro-6-diethylaminofluorane, 2-bromo-6-diethylaminofluorane, 2-
Chlor-6-dipropylaminofluorane, 2-chloro-6-dibutylaminofluorane, 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-diethylamino Fluoran, 2- (2,3-dichloroanilino) -3-chloro-6-diethylaminofluorane, 2-ethoxyethylamino-3-chloro-6-dibutylaminofluorane, 2-benzylamino-4-chloro-6 -(N-ethyl-p-toluidino) fluorane, 2-dibenzylamino-4-chloro-6- (N-ethyl-p-toluidino)
Fluoran, 2- (α-phenylethylamino) -4-
Chlor-6-diethylaminofluorane, 2- (N-benzyl-p-trifluoromethylanilino) -4-chloro-6-diethylaminofluorane and the like.

Besides the general formula (10), there are many fluoran compounds preferable as the color former used in the present invention, and the following compounds are specifically exemplified. 2-anilino-3-
Methyl-6-pyrrolidinofluorane, 2-anilino-3
-Chlor-6-pyrrolidinofluorane, 2-anilino-
3-Methyl-6- (N-ethyl-N-tetrahydrofurfurylamino) fluorane, 2-mesidino-3-methyl-4 ', 5'-benzo-6-diethylaminofluorane, 2- (m-trifluoromethyl) Anilino) -3-methyl-6-pyrrolidinofluorane, 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-N-p-chlorophenyl-methylamino) -6-pyrrolidinofluorane, 2- (N-n-propyl-m-trifluoromethylanilino) -6-morpho Rinofluorane, 1,2-benzo-6-diethylaminofluorane, 1,2-benzo-
6- (N-ethyl-N-isoamylamino) fluorane, 1,2-benzo-6-dibutylaminofluorane,
1,2-benzo-6- (di-n-amylamino) fluorane, 1,2-benzo-6- (di-n-hexylamino) fluorane, 1,2-benzo-6- (N-methyl-
N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-Nn-octylamino) fluorane, 1,2-benzo-6- (N-ethyl-p-toluidino) fluorane, 1, 2-benzo-6-diallylaminofluorane, 1,2-benzo-6- (N-ethoxyethyl-N-ethylamino) fluorane and the like.

There are many compounds other than the fluoran compound which are preferable as the color former used in the present invention, and the following compounds are specifically mentioned. Benzoleucomethylene blue, 2- [3,6-bis (diethylamino)]-6-
(0-chloranilino) xanthyl lactam benzoate,
2- [3,6-bis (diethylamino)]-9- (0-
Chloranilino) xanthyl lactam benzoate, 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- (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-dimethoxyaminophenyl) -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-)
Chlor-5-methoxyphenyl) phthalide, 3,6-bis (dimethylamino) fluorenspiro (9,3 ′)-
6'-dimethylaminophthalide, 6'-chloro-8'-
Methoxy-benzoindolino-spiropyran, 6'-bromo-2'-methoxy-benzoindolino-spiropyran and the like.

In the reversible thermosensitive recording medium of the present invention, the ratio of the color former to the developer in the reversible thermosensitive recording layer needs to be appropriately selected depending on the physical properties of the compound used. The range is generally in the range of 1 to 20 and preferably 2 to 10 of the color developing agent to the color developing agent in a molar ratio. The color developer and the color developer may be used individually or as a mixture of two or more kinds, but the decolorizing property changes depending on the ratio of the color developer and the color developer, and there are relatively many color developers. In this case, the decolorization start temperature becomes low, and when it is relatively small, the decolorization becomes sharp with respect to the temperature. Therefore, it is desirable that this ratio be appropriately selected according to the use and purpose.

The reversible thermochromic composition constituting the reversible thermosensitive recording layer basically consists of a color developer and a color developer, but various properties such as decoloring property and storability are improved. For the purpose, an additive having an effect of controlling crystallization of the color developer can be contained. The reversible thermosensitive recording medium of the present invention comprises a support and a recording layer containing a reversible thermochromic composition. The basic constitution of the reversible thermosensitive recording medium is that the lowermost layer is provided with a support, and a reversible thermosensitive recording layer and a protective layer are sequentially laminated thereon, and the protective layer is a reversible adhesive made of a thermosetting resin. It adheres to the thermal recording layer. The support is paper, synthetic paper, a plastic film or a composite thereof, a glass plate, and the like, as long as it can hold the reversible thermosensitive recording layer.

The reversible thermosensitive recording layer may be in any form as long as the above thermochromic composition is present. For example, a developer and a color former are mixed and melted to form a film, which is cooled. It may be used as a reversible thermosensitive recording layer. However, it is usually good to sufficiently disperse the color developer and the color former in the binder resin to form a reversible thermosensitive recording layer, and a reversible thermosensitive recording medium having a long life can be obtained by this method. As the binder resin, for example, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polystyrene,
Styrene-based copolymer, phenoxy resin, polyester,
Aromatic polyesters, polyurethanes, polycarbonates, polyacrylic acid esters, polymethacrylic acid esters, acrylic acid copolymers, maleic acid copolymers, polyvinyl alcohol, chlorinated vinyl chloride resins, mixtures of these resins and the like are used. .

The color developer and the color developer can be used as they are or in a microcapsule. Microencapsulation of the color developer and the color developer may be performed by a known method such as a coacervation method, an interfacial polymerization method, an in situ polymerization method. The reversible thermosensitive recording layer is formed by uniformly dispersing or dissolving a color former and a developer together with a binder resin in water or an organic solvent according to a conventionally known method, and coating and drying the same on a support. It can be carried out. The role of the binder resin in the reversible thermosensitive recording layer is to prevent the reversible thermochromic composition from aggregating due to repeated coloring and decoloring, and to keep the reversible thermochromic composition uniformly dispersed. Especially. In particular,
Since the composition often agglomerates and becomes non-uniform due to the application of heat during color development, it is preferable that the binder resin has high heat resistance. In the reversible thermosensitive recording medium of the present invention, if necessary,
For the purpose of improving coating properties or recording properties, various additives used in ordinary thermal recording paper, such as dispersants, surfactants, polymeric cationic conductive agents, fillers, color image stabilizers, and antioxidants. Agents, light stabilizers, lubricants and the like can be added to the reversible thermosensitive recording layer.

Since the protective layer prevents the surface from being deformed or discolored by heat and pressure when heat is applied, it is extremely effective to install the protective layer for many times of use. In addition, the protective layer may have a role of improving chemical resistance, water resistance, abrasion resistance, head matching property, and the like.
Therefore, it is preferable that the material forming the protective layer has high heat resistance as well as high strength and chemical resistance. A resin dispersed or dissolved in a solvent is applied to the reversible thermosensitive recording layer and dried to produce the conventional material. With the protective layer forming method, a sufficiently satisfactory protective layer cannot be obtained. The present invention is characterized by forming a protective layer by adhering a resin film having high heat resistance and strength onto the recording layer in order to obtain high heat resistance and strength that cannot be obtained by the conventional protective layer forming method. There is. As the heat-resistant film, a resin film having a melting point of 180 ° C. or more and high strength is preferable, and a film of fluorine resin, polyimide resin, or the like is used.

For example, in the case of fluorine resin, tetrafluoroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene-ethylene copolymer resin. Polymer resin, trifluoroethylene chloride resin, vinylidene fluoride resin, vinyl fluoride resin, trifluoroethylene chloride-
Films of ethylene copolymer resin, fluorine-containing polybenzoxazole resin, etc. are used.
Films of polyamide imide, polyparabanic acid, polyamide, polyether imide, polyether ether ketone, aromatic polyester, polyphenylene sulfide, polysulfone and the like can also be used. When these films are used as the protective layer, it is desirable to use a film having a film thickness of 25 μm or less from the viewpoint of the thermal sensitivity and economical efficiency of the reversible thermosensitive recording medium. In the present invention, the heat-resistant film is adhered onto the reversible thermosensitive recording layer to form the protective layer. This adhesion is preferably performed by the dry laminating method,
The adhesive is preferably a thermosetting resin generally used in the dry laminating method. It should be noted that when a thermoplastic resin is used as the adhesive, a recorded image is decolored over time, but such a phenomenon is not observed when a thermosetting resin is used. It is speculated that this phenomenon occurs because the resin having plasticity acts as a solvent on the color former and the developer.

Specifically, an adhesive for adhering the protective layer is
Epoxy resins such as bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, o-cresol novolac type epoxy resin, polyphenol type epoxy resin, polyglycidyl amine type epoxy resin, glycidyl alcohol type epoxy resin, glycidyl ester type epoxy resin; Xylene-formaldehyde resin; urea resin; melamine resin; benzoguanamine resin; acetoguanamine resin; phenol resin; saturated or unsaturated polyester resin; furan resin; polyol resin and the like.

The curing agent used for curing the thermosetting resin varies depending on the type of resin. For example, amines include ethylenediamine, diethylenetriamine, triethylenetetramine, dimethylaminopropylamine,
Diethylaminopropylamine, amine glycidyl ether adduct, hexamethylenetetramine, benzyldimethylamine, α-methylbenzyldimethylamine, 2,
6-di (dimethylaminomethyl) phenol, 2,4
6-tri (dimethylaminomethyl) phenol, piperidine, pyridine, metaphenylenediamine, 4,4'-
Diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfone, 1-cyanoguanidine, boron trifluoride monoethylamine, boron trifluoride ethanolamine,
Examples include polyalkylamines. In addition, nitrogen-containing compounds such as carboxylic acid amides, benzenesulfonic acid amides, ammonium salts such as ammonium chloride, and hydrochlorides of amino alcohols are also used. Further, p-toluenesulfonic acid, oxalic acid, phthalic anhydride, maleic anhydride, hexahydrophthalic acid, trimellitic anhydride, chlorendic anhydride, pyromellitic anhydride, methyl phthalate-maleic acid adduct, dodecylsuccinic acid. Organic acids and anhydrides such as anhydrides and dichloromaleic anhydride are also used as curing agents. In addition, polyisocyanates having two or more isocyanate groups and various peroxides that thermally generate radicals are also used as a curing agent. Here, the peroxide used for the curing agent includes dialkyl peroxide, peroxyketal, diacyl peroxide, hydroperoxide,
Peroxides of various fields such as peroxyesters and ketone peroxides are included. The above-mentioned thermosetting resins and their curing agents may be used alone or in admixture of two or more, and it is important to select a curing agent suitable for the resin used.

The formation of a recorded image is not particularly limited by a heating pen, a thermal head, laser heating, etc. depending on the purpose of use. Similarly, the erasing of the recorded image is not particularly limited as long as the erasing temperature conditions such as the heating roller, the sheet heating element, the constant temperature bath, the warm air, and the thermal head are given. Further, so-called overwriting is possible in which the recorded image is erased by the thermal head set to the erasing temperature and at the same time the recorded image is formed by another thermal head set to the recording temperature.

[0047]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. The parts and% shown below are based on weight.

Example 1 2- (o-chloroanilino) -6-dibutylaminofluorane 10 parts α-hydroxyoctadecylphosphonic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide) 30 parts Toluene 135 Part Methyl ethyl ketone (hereinafter abbreviated as MEK) 135 parts The above composition was put in a sample bottle together with a stainless ball and dispersed for 48 hours with a tabletop ball mill to disperse the average particle size of α-hydroxyoctadecylphosphonic acid to about 1 to 3 μm. The dispersion prepared as described above was applied to a transparent polyester film having a thickness of 100 μm by a wire bar so that the applied thickness was about 8.0 μm, and dried to prepare a reversible thermosensitive recording medium. This reversible thermosensitive recording medium was once colored at 170 ° C., placed in a dryer at 75 ° C. for 5 minutes to be erased, and then an adhesive-coated aromatic polyamide film having a thickness of 4 μm was laminated on the recording layer and pressed. 2K
It was pressure-bonded with a 130.degree. C. heat roll. This was further aged in a constant temperature bath at 40 ° C. for 15 hours to prepare a reversible thermosensitive recording medium provided with a heat resistant film layer. As the adhesive, 10% of Byron 300 (saturated polyester) manufactured by Toyobo Co., Ltd. and Coronate L (curing agent) manufactured by Nippon Polyurethane Industry Co., Ltd. was used.
The polyamide film was dissolved in a MEK mixed solvent so as to have a dry adhesion amount of 3 g / m ^2, and was applied to the recording layer after drying.

Example 2 2-anilino-3-methyl-6-10 parts (N-ethyl-p-toluidino) fluorane octadecylphosphonic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide) 30 Parts Toluene 135 parts MEK 135 parts The above composition was placed in a sample bottle together with stainless balls and dispersed for 48 hours with a tabletop ball mill to disperse octadecylphosphonic acid to an average particle size of about 1 to 3 μm. The dispersion prepared as described above was applied to a transparent polyester film having a thickness of 100 μm by a wire bar so that the applied thickness was about 8.0 μm, and dried to prepare a reversible thermosensitive recording medium. This reversible heat-sensitive recording medium was once colored at 120 ° C., put in a dryer at 70 ° C. for 5 minutes, and after erasing, a 6 μm thick vinylidene fluoride resin film coated with an adhesive was laminated on the recording layer, Pressure 2 kg 130
It was pressure-bonded with a heat roll. This was further aged in a constant temperature bath at 40 ° C. for 15 hours to prepare a reversible thermosensitive recording medium provided with a heat resistant film layer. As the adhesive, a 1: 1 mixture of Nippon Polyurethane Industry Co., Ltd. Nippon Polan 3107 and Nippon Polyurethane 3124 was used, and 15% of Nippon Polyurethane Industry Co., Ltd. Coronate L was used as a curing agent.
This composition was added, dissolved in a mixed solvent of ethyl acetate-MEK, applied on the above vinylidene fluoride resin film so that the dry adhesion amount was 4 g / m ^2, and dried and then laminated on the recording layer.

Example 3 2-anilino-3-methyl-6- (Nn-hexyl 10 parts -N-iso-amylamino) fluorane octadecylmalonic acid 30 parts polystyrene 30 parts toluene 135 parts ethyl acetate 135 parts The above composition Was melted and coated on a transparent polyester film having a thickness of 100 μm with a wire bar to a coating thickness of about 8.0 μm and dried to obtain a reversible thermosensitive recording medium.
This reversible thermosensitive recording medium was once colored at 150 ° C.
Put it in a dryer at 5 ° C for 5 minutes, and after bleaching, apply a 6 μm thick polyphenylene sulfide film on the recording layer, press it with a 130 ° C heat roll with a pressure of 2 Kg, and then keep it at 40 ° C constant temperature. A reversible thermosensitive recording medium provided with a heat resistant film layer was prepared by aging in a bath for 24 hours. As the adhesive, a two-component polyurethane adhesive (trade name: Takelac A-310 / Takenate A-3) manufactured by Takeda Pharmaceutical Co., Ltd. is used, and the dry adhesion amount is 3 g / m.
^The polyphenylene sulfide film was coated so as to have a weight of ² , dried and then pressure-bonded onto the recording layer.

Example 4 1,2-benzo-6- (di-n-butylamino) fluorane 10 parts Eicosylphosphonic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide) 30 parts Toluene 135 parts MEK 135 parts The above composition is put into a sample bottle together with a stainless ball and dispersed for 48 hours with a tabletop ball mill to disperse the eicosylphosphonic acid to an average particle size of about 1 to 3 μm. The dispersion prepared as described above was applied to a transparent polyester film having a thickness of 100 μm with a wire bar so that the applied thickness was about 8.0 μm, and dried to obtain a reversible thermosensitive recording medium. This reversible thermosensitive recording medium was once colored at 120 ° C., put in a dryer at 80 ° C. for 5 minutes to be erased, and then a 5 μm-thick polyparabanic acid film coated with an adhesive was stuck on the recording layer, and the pressure was 2 kg. The product was pressure-bonded with a 130 ° C. heat roll and further aged in a constant temperature bath of 40 ° C. for 15 hours to prepare a reversible thermosensitive recording medium provided with a heat resistant film layer. The adhesive is a saturated copolyester manufactured by Unitika Ltd. (trade name: Elitel UE-3221-3
0S), 15% of Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd. was added as a curing agent, and this composition was dissolved in a toluene-MEK mixed solvent to give a dry adhesion amount of 3
The polyparabanic acid film was coated so as to be g / m ² , dried and then laminated on the recording layer.

Example 5 2-anilino-3-methyl-6- (N-n-hexyl 10 parts -N-iso-amylamino) fluorane octadecylphosphonic acid 30 parts polycarbonate 30 parts tetrahydrofuran (THF) 216 parts 1,4- Dioxane 54 parts The above composition is put in a sample bottle together with a stainless steel ball, and dispersed for 48 hours with a tabletop ball mill to disperse octadecylphosphonic acid to an average particle size of about 1 to 3 μm. The dispersion prepared as described above was applied to a transparent polyester film having a thickness of 100 μm by a wire bar so that the applied thickness was about 8.0 μm, and dried to prepare a reversible thermosensitive recording medium. This reversible thermosensitive recording medium was once colored at 175 ° C., put in a dryer at 70 ° C. for 5 minutes, and after erasing, a polyimide film having a thickness of 4 μm coated with an adhesive was laminated on the recording layer, and a pressure of 2 Kg was applied. A reversible thermosensitive recording medium provided with a heat-resistant film layer was prepared by pressure bonding with a 130 ° C. heat roll and further aging for 15 hours in a constant temperature bath of 45 ° C. Epoxy resin N-740 (phenol novolac type epoxy resin) manufactured by Dainippon Ink and Chemicals, Inc. is used as the adhesive, and Rikacid TMEG manufactured by Shin Nippon Rika Co., Ltd. is used as a curing agent at an equivalent ratio of 1: 1. The composition was added in a ratio of 0.1%, the composition was dissolved in a mixed solvent of ethyl acetate-MEK, and the composition was applied to the polyimide film so that the dry adhesion amount was 4 g / m ^2, and dried and then laminated to the recording layer.

Example 6 2-anilino-3-methyl-6- (di-n-10 parts amylamino) fluorane octadecylthiomalic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide) 30 parts Toluene 135 parts Ethyl acetate 135 parts The above composition was dissolved and coated on a transparent polyester film having a thickness of 100 μm with a wire bar to a coating thickness of about 8.0 μm and dried to obtain a reversible thermosensitive recording medium. .
This reversible thermosensitive recording medium was colored once at 120 ° C.
An aromatic polyamide film having a thickness of 14 μm coated with an adhesive after being put in a dryer at 0 ° C. for 5 minutes to be erased was stuck on the recording layer, pressure-bonded with a 130 ° C. heat roll having a pressure of 2 Kg, and further 40 ° C. It was aged for 15 hours in a constant temperature bath to prepare a reversible thermosensitive recording medium provided with a heat resistant film layer. Byron 500 (saturated polyester) manufactured by Toyobo Co., Ltd. is used as an adhesive, and 15% of Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd. is added as a curing agent to it.
This composition was dissolved in a toluene-MEK mixed solvent, coated on the aromatic polyamide film so that the dry adhesion amount was 4 g / m ² , dried, and then laminated with a recording layer.

Example 7 2-Methyl-6- (di-n-butylamino) fluorane 10 parts α-hydroxyoctadecylphosphonic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide) 30 parts Toluene 135 parts MEK 135 parts The above composition is put in a sample bottle together with a stainless steel ball, and dispersed for 48 hours with a tabletop ball mill so that α-hydroxyoctadecylphosphonic acid has an average particle size of about 1 to 3 μm. The dispersion prepared as described above was applied to a transparent polyester film having a thickness of 100 μm by a wire bar so that the applied thickness was about 8.0 μm, and dried to prepare a reversible thermosensitive recording medium. This reversible thermosensitive recording medium was once colored at 170 ° C., put in a dryer at 75 ° C. for 5 minutes, and then a polysulfone film having a thickness of 12 μm, to which an adhesive was applied after the color was erased, was stuck on the recording layer, and the pressure was 2 kg.
Was pressed by a 130 ° C. heat roll and further aged in a constant temperature bath of 50 ° C. for 15 hours to prepare a reversible thermosensitive recording medium having a heat resistant film layer. TEPIC-S (epoxy resin having triazine ring) manufactured by Nissan Chemical Industries, Ltd. is used as the adhesive, and Shin Nihon Rika Co., Ltd. is used as the curing agent.
Rikacid HH HHPA manufactured by the present invention was added at an equivalence ratio of 1: 1 and then a MEK solution of this composition was dried and attached at a rate of 4 g /
It is applied to the polysulfone film so that it becomes m ² ,
After drying, it was attached to the recording layer.

Comparative Example 1 A reversible thermosensitive recording medium was prepared in the same manner as in Example 1, except that the adhesive agent (Vylon 300 / Coronate L) used in Example 1 was replaced with only Byron 300. Comparative Example 2 A reversible thermosensitive recording medium was prepared in the same manner as in Example 2 except that only Nipollan 3124 was used in place of the adhesive used in Example 2 (equivalent mixture of Nipolan 3107 and Nipolan 3124 / Coronate L). .

A printing apparatus equipped with a thermal head using the reversible thermosensitive recording media of Examples and Comparative Examples (head 8 dots / mm, applied voltage 13.3 V, pulse width 0.8 ms).
An image was recorded by means of the following, and the following evaluations were carried out. The results are shown in Table 1. "Color development color tone" The color development color tone immediately after recording was visually observed. "Image recording density" The image density immediately after recording is Macbeth densitometer (made by Macbeth Co., Ltd.
RD-914 type). “Repeatability” An image was recorded on the recording medium by the printing device, and then the erasing conditions (70 ° C., 75 ° C. or 80 ° C. × 5) described in Examples were used.
It was erased in (1 minute). This operation was repeated 20 times, and the deterioration of the function and the surface state of the heat resistant film were visually observed, and evaluated by ◯ (good: ◯, bad: x, intermediate: Δ). "Image storability" The recorded image was stored in a constant temperature bath at 40 ° C for 24 hours, and the deterioration state was visually observed. The evaluation was carried out by ◯ ×, the one with little deterioration was marked with ◯, the one with severe deterioration was marked with x, and the middle one was marked with Δ.

[0057]

[Table 1] From Table 1, it is clear that the reversible thermosensitive recording medium of the example has an image storability of a practical level, but that of the comparative example cannot store an image at 40 ° C.

[0058]

INDUSTRIAL APPLICABILITY The reversible thermosensitive recording medium of the present invention can be colored by heating, melting and mixing a color former and a developer contained therein, and a composition in a color developing state can be heated at a temperature higher than its melting temperature. It is possible to change to the decolored state by heating at a low temperature. Such coloring and decoloring can be repeated, and the coloring and decoloring states can be kept at room temperature. Further, in the reversible thermosensitive recording medium of the present invention, the contrast of the obtained image is high, the image erasability is good, and the hue of the color image is not limited at all, and the hue can be freely selected by changing the color former. it can. The reversible thermosensitive recording medium of the present invention is provided with a protective layer made of a heat-resistant film on the thermosensitive recording layer, and by adhering the protective layer to the recording layer with a thermosetting resin, the surface heat resistance and the preservation of printed images Since the property is improved and troubles such as surface damage due to a heat source contacting at the time of recording and erasing an image are reduced, the life of the recording medium is increased. In particular, the effect of using a thermosetting resin for the adhesive of the heat resistant film is great,
It is also clear from the examples that the image storability is significantly improved by using the thermosetting resin.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between color density and temperature of a reversible thermosensitive recording medium of the present invention, and is an explanatory view of the principle of color development and color erasing. The solid line (A → B → C) indicates the image forming process, and the broken line (C
→ D → A) shows an image erasing process.

FIG. 2 is an explanatory diagram of an image forming process and an image erasing process.

[Explanation of symbols]

 1 Support 2 Reversible Thermosensitive Recording Layer 3 Colored Image 4 Thermal Head 5 Heating Roller

Claims (1)

[Claims] 1. A thermosensitive recording layer containing an electron-donating color-forming compound and an electron-accepting compound is provided on a support, and a color-recorded state is formed by heating and melting, and heating at a temperature lower than the color-recording temperature. In a reversible thermosensitive recording medium which forms a decolored state in which recording disappears, a protective layer made of a heat resistant film is provided on the upper surface of the thermosensitive recording layer, and the thermosensitive recording layer and the protective layer are made of a thermosetting resin. A reversible thermosensitive recording medium characterized by being adhered.