JPH0885255A - Reversible thermosensitive recording medium - Google Patents

Abstract

PURPOSE: To provide a reversible thermosensitive recording medium capable of improving discoloration without causing decrease in its recording property and recording preservation. CONSTITUTION: The reversible thermosensitive recording medium is that a recording layer is provided on the carrier, which has at least one of a leuco compound, phenol hydroxyl group and carboxyl group, and amino group as a functional group or a part of a chloride compound, and consists mainly of a developing and discoloring agent and binder for developing and discoloring the leuco compound through the agency of them, and also that the recording layer colors or discolors by controlling thermal energy. Blended in the recording layer is a discoloring assistant (amino-modified silicone oil or the like) having relatively weaker basic than the developing and discoloring agent that effects during the discoloring period and acts on the leuco compound allowing it to be discolored. Also, the discoloring assistant effects in the discoloring period and improve the discoloring property, and gives no hindrance to the recording property and recording preservation property at the time of developing and preserving period due to its weak discoloring effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a recording layer mainly composed of a leuco compound, a color-developing agent and a binder, and controls the thermal energy applied to the recording layer to develop (record) and decolorize the recording layer. The present invention relates to a reversible thermosensitive recording medium that performs (erasing), and in particular, "fog color development phenomenon" is unlikely to occur at the manufacturing stage of this recording medium, and the erasability can be improved without lowering the recording property and the record keeping property. The present invention relates to a reversible thermosensitive recording medium.

[0002]

2. Description of the Related Art In recent years, a reversible thermosensitive recording medium has been actively developed in which recording and erasing can be repeatedly performed by appropriately controlling applied thermal energy.

For example, JP-A-54-119377, JP-A-63-39377, and JP-A-63-41.
No. 186, JP-A-2-188294, etc., a reversible thermosensitive recording medium having a recording layer mainly composed of a resin base material and an organic low molecular weight substance dispersed in the resin base material. Is listed. In this reversible thermosensitive recording medium, the transparency of the recording layer is physically changed by controlling the thermal energy, and recording and erasing are performed reversibly.

However, in this reversible thermosensitive recording medium, the transparency of the recording layer is physically changed to indirectly perform recording and erasing, and the recording layer itself is directly colored or erased for recording. It was not a recording medium for erasing.

On the other hand, a reversible thermosensitive recording medium for directly recording and erasing by chemically coloring or erasing the recording layer itself is disclosed in JP-A-2-188294 and JP-A-2.
No. 505365. That is,
This reversible thermosensitive recording medium comprises a leuco compound and a color-developing agent (amphoteric compound) having at least one of a phenolic hydroxyl group and a carboxyl group and having an amino group as a functional group or as a part of a salt compound as main components. The recording layer was prepared.

Since the above-mentioned developer / color-reducing agent which is an amphoteric compound exhibits the properties of an acid or the properties of a base by the action of heat, hydrogen ions released by acting as an acid under high temperature heating act as an lactone ring of a leuco compound. Ring-opens to develop the leuco compound, while under low temperature heating it acts as a base to close the lactone ring and reduce the color of the leuco compound.
Therefore, since the recording layer itself chemically develops or erases color, it functions as a medium capable of directly recording and erasing.

[0007]

By the way, in a reversible thermosensitive recording medium containing the above-described color-developing and reducing agent and a leuco compound as main components, the hydrogen ion reversibly released from the color-developing and reducing agent and the above-mentioned leuco compound are Since the reaction is used, there is a problem that the color forming reaction and the color erasing reaction tend to occur competitively in the recording layer, and it is difficult to thermally control these reactions.

That is, when a sensitizer or the like is mixed in the recording layer to increase the color development sensitivity (density) of the recording layer, the decoloring property of the recording layer is deteriorated and the unerased portion is liable to occur during erasing. On the contrary, when a basic compound such as amine is blended in the recording layer to enhance the decoloring property of the recording layer, the coloring property is deteriorated and recording becomes difficult, or there is a part where the color is developed. There is a problem that the color is easily erased over time and the recording storability thereof is deteriorated.

When a leuco compound or a color-developing / reducing agent having a high solvent solubility is applied during the production of this reversible thermosensitive recording medium, a so-called color-developing reaction is caused after coating and drying, and the so-called base density increases. It had the problem of causing the "fog coloring phenomenon".

The present invention has been made by paying attention to such a problem, and the problem is that the above-mentioned "fog coloring phenomenon" is hard to occur in the manufacturing stage of the recording medium.
Moreover, it is an object of the present invention to provide a reversible thermosensitive recording medium capable of improving the decoloring property without deteriorating the recording property and the recording storability.

[0011]

That is, the invention according to claim 1 has a leuco compound and at least one of a phenolic hydroxyl group and a carboxyl group and an amino group as a functional group or as a part of a salt compound. A recording layer mainly composed of a color-developing agent that acts on the leuco compound to develop or reduce the color, and a binder is provided on the support, and the recording layer develops or erases color by controlling thermal energy. Assuming a reversible thermosensitive recording medium, an erasing aid is added to the recording layer, which has a relatively weaker basicity than the developing and decoloring agent that acts at the time of erasing and acts on a leuco compound at the time of erasing to reduce the color of the leuco compound. It is characterized by that.

Here, the recording and erasing principles of the reversible thermosensitive recording medium according to the present invention are the same as those of the reversible thermosensitive recording medium according to the conventional example described above. That is, for a reversible thermosensitive recording medium having a recording layer containing a leuco compound, the above-mentioned color-developing agent and a binder as main components, thermal energy (h1) such as high temperature (300 ° C. or higher), short time (several) When subjected to heat treatment (milliseconds to several hundreds of milliseconds), hydrogen ions are released from the phenolic hydroxyl group or carboxyl group of the color-developing agent and react with the leuco compound to open the leuco compound to form a colored image. . Also, for this image, another heat energy (h2) such as low temperature (a temperature near the melting point of the color developing / reducing agent or higher, for example 100
(~ 200 ° C), when subjected to a heat treatment for a long time (1 second or more), hydrogen ions are deprived of the leuco compound by the action of the amino group of the developer and decolorizer, and the leuco compound is ring-closed and erased. . Furthermore, when the erased recording layer is again subjected to heat treatment with heat energy (h1), an image is formed again. This image formation and erasure can be repeated, and the image formation state or the image erasure state is maintained unless heat energy is applied.

In the reversible thermosensitive recording medium according to the first aspect of the present invention, the reversible thermosensitive recording medium has a relatively weak basicity as compared with the decolorizing agent which acts at the time of decoloring and acts on the leuco compound at the time of decoloring to reduce the color. When the recording layer in the image forming state is subjected to heat treatment with heat energy (h2), a decoloring aid is blended in the recording layer, and in addition to the action of the amino group of the color-developing agent, The decolorizing aid also acts to deprive the leuco compound of hydrogen ions and return them to the color-developing / reducing agent, so that the leuco compound at the heating site can be more completely closed. Therefore, it becomes possible to remarkably improve the decoloring property in the reversible thermosensitive recording medium.

On the other hand, when the heat treatment of heat energy (h1) is applied to the recording layer in the image erasing state, since this treatment is heating for a short time, the recording layer at the treated portion is instantly solidified. In addition, the above-mentioned decolorizing aid compounded in the recording layer is relatively weaker in basicity than the developing and decoloring agent that acts at the time of decoloring, and the decolorizing effect on the leuco compound is weak, so that the presence of the decolorizing aid is The color forming property of the compound is not hindered, and since the decoloring effect of the decoloring aid on the leuco compound is weak, the image forming state is maintained unless heat energy is applied, and the presence of the decolorizing aid is present. Does not hinder the recording storability of the recording layer.

Further, even when a leuco compound or a color-developing / reducing agent having a high solvent solubility is applied in the production of the reversible thermosensitive recording medium according to the present invention, the leuco compound has a coloring property due to the presence of the decoloring auxiliary agent. Since it is suppressed, it is possible to avoid the above-mentioned "fog coloring phenomenon".

As the material constituting the decoloring aid, any neutral or weakly basic compound having a relatively weaker basicity than the developing and decoloring agent acting at the time of decoloring can be applied. In this case, the compound having a stronger affinity for the leuco compound in which the lactone ring is closed and in the color-reduced state is stronger than the affinity for the leuco compound in which the lactone ring is opened and in the color-developed state. When the auxiliary agent is configured, the function of the above-described decoloring auxiliary agent can be further improved.

Next, the inventions according to claims 2 to 5 relate to the invention in which the material constituting the decoloring aid is specified.

That is, the invention according to claim 2 is premised on the reversible thermosensitive recording medium according to claim 1, wherein the decolorizing aid is composed of a compound having polysiloxane in the molecule. It is characterized by that.

The compound having polysiloxane in the molecule is, for example, amino-modified, epoxy-modified,
Examples thereof include, but are not limited to, carbinol-modified, methacryl-modified, and other reactive silicone oils, and polyether-modified, alkyl-modified, fluorine-modified, and other non-reactive silicone oils.

The invention according to claim 3 is premised on the reversible thermosensitive recording medium according to claim 1, wherein the decolorizing aid is composed of a compound having a polyoxyethylene chain in the molecule. It is characterized by that.

Examples of the compound having a polyoxyethylene chain in the molecule include glycols such as polyethylene glycol, diethylene glycol diethyl ether, diethylene glycol monoethyl ether, triethylene glycol dimethyl ether, polyoxyethylene sorbitan monolaurate and poly Examples thereof include nonionic surfactants such as oxyethylene stearyl ether and polyoxyethylene nonylphenol, but are not limited thereto.

A compound having a polysiloxane or polyoxyethylene chain in the molecule (decoloring aid according to claim 2 or claim 3), for example, silicone oil, is used in addition to functioning as a decoloring aid. Generally, it has an advantage that it has functions such as a leveling (flattening) effect of a coating film, a lubricating effect, and blocking prevention.

The invention according to claim 4 is premised on the reversible thermosensitive recording medium according to claim 1, wherein the decolorizing aid is composed of a carboxylic acid ester. To do.

Examples of applicable carboxylic acid esters include ethyl benzoate, lauryl benzoate, butyl stearate, dibutyl maleate, dimethyl terephthalate, dioctyl phthalate, distearyl phthalate, dioctyl maleate and the like. However, the present invention is not limited to these. In particular, melting point 30 ° C to 1
When a carboxylic acid ester at 00 ° C. is applied, it is preferable because the recording storability at room temperature can be made more stable.

The decolorizing aid may be constituted by using two or more kinds of the compounds specified in claims 2 to 4 in combination. The invention according to claim 5 relates to the invention specifying this configuration.

That is, the invention according to claim 5 is premised on the reversible thermosensitive recording medium according to claim 1, wherein the decolorizing aid is a compound having a polysiloxane in the molecule, or a polysiloxane in the molecule. Compounds having an oxyethylene chain and at least 2 selected from carboxylic acid esters
It is characterized in that it is composed of more than one species.

Further, the degree of decoloring property can be adjusted to a desired level by appropriately adjusting the blending amount of the decoloring aid composed of these compounds. The blending amount of the decolorizing aid in the recording layer varies depending on the kind of the compound constituting the decolorizing aid, but with respect to 1 part by weight of the leuco compound,
A range of 0.01 to 3 parts by weight is suitable, and a range of 0.1 to 1 part by weight is particularly preferable.

Next, each material constituting the thermosensitive recording medium according to the present invention will be described. First, as in the conventional case, as the support, a plastic material such as paper or plastic card, a metal material, a synthetic polymer, etc. Examples of the material include materials, but the material is not limited thereto.

As the leuco compound which constitutes a part of the recording layer, xanthene, spiropyran, lactone having a partial skeleton such as lactone, sultone and spiropyran,
Fluoran, sultone, etc. are used. Specific examples of these include crystal violet lactone, 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide, 3-diethylamino-7-chlorofluorane, and 2- (2-fluorophenylamino). -6
-Diethylaminofluorane, 2- (2-fluorophenylamino) -6-di-n-butylaminofluorane,
3-diethylamino-7-cyclohexylaminofluorane, 3-diethylamino-5-methyl-7-t-butylfluorane, 3-diethylamino-6-methyl-7-
Anilinofluorane, 3-diethylamino-6-methyl-7-p-butylanilinofluorane, 3-cyclohexylamino-6-chlorofluorane, 2-anilino-3
-Methyl-6- (N-ethyl-p-toluidino) -fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-7-cyclohexylaminofluorane, 3-N-methylcyclohexylamino -6
Examples include, but are not limited to, -methyl-7-anilinofluorane and 3-N-ethylpentylamino-6-methyl-7-anilinofluorane. Moreover, you may use these 2 or more types simultaneously.

On the other hand, the above-mentioned color-developing / reducing agent is a compound having both an acidic group consisting of a phenolic hydroxyl group or a carboxyl group and a basic group consisting of an amino group, which becomes acidic or basic due to the difference in thermal energy and becomes a leuco compound. It develops and reduces the color of compounds. The basic group may be present as a functional group or may be present as a part of the salt compound. Examples of the existing color developer having an amino group as a functional group include aminobenzoic acids, hydroxyaminobenzoic acids, aminophenols and the like. Further, as having a basic group as a part of the salt compound, a salt or complex salt of a compound having a phenolic hydroxyl group or a carboxyl group and a compound having an amino group, for example, hydroxybenzoic acids, hydroxysalicylic acids, gallic acid. Examples thereof include salts or complex salts of acids, acids such as bisphenolacetic acid, and bases such as aliphatic amines, phenylalkylamines and tolylalkylamines. Specific examples of these existing color developers include Japanese Patent Application No. 1-89508, Japanese Patent Application No. 1-89509, Japanese Patent Application No. 1-89510, filed by the applicant of the present application, Japanese Patent Application 1-1
20888 specification, Japanese Patent Application No. 1-2228079 specification, Japanese Patent Application No. 1-228080 specification, and Japanese Patent Application No. 1
Examples thereof include materials described in Japanese Patent No. 228081. Further, two or more of these color-developing and reducing agents may be used at the same time. The ratio of the leuco compound to the color-developing / reducing agent is not particularly limited, but the range of 1 to 20 parts by weight, preferably 2 to 10 parts by weight, of the leuco compound is exemplified.

The recording layer of the reversible thermosensitive recording medium according to the present invention may be in any form as long as it contains the above-mentioned leuco compound, a color-developing agent and a binder resin.
Usually, it is formed by coating the support with a solution or dispersion of it dissolved in water or an organic solvent and drying it. The binder resin at this time is not particularly limited, for example, acrylic resin, polyester, polyurethane, polyurea, melamine resin, polycarbonate, polyamide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl chloride,
Polymers such as polyvinyl butyral, paraffin wax, polyethylene wax, carnauba wax,
In addition to waxes such as microcrystalline wax and stearic acid amide, celluloses such as hydroxyethyl cellulose, carboxymethyl cellulose, cellulose acetate and methoxycellulose, gelatin, casein, starch, and rubbers can be mentioned. Among these resins, in order to improve the repetitive characteristics and heat resistance of the reversible thermosensitive recording material, it is particularly preferable to apply a thermosetting resin or a heat resistant resin. Moreover, it is natural that two or more kinds of these resins may be used in combination.

The leuco compound, the current color developer, and the decoloring aid may be present in the recording layer in the form of being encapsulated in microcapsules. Various known methods are used as the microencapsulation method at this time, and examples thereof include an interfacial polymerization method, an in situ polymerization method, a coacervation method, a spray drying method, and a submerged drying method.

Further, in the recording layer of the reversible thermosensitive recording medium according to the present invention, in addition to the leuco compound, the color-developing / reducing agent, the decoloring aid, and the binder resin, it is applied to ordinary thermosensitive recording paper. Additives may be added. Examples of such additives include sensitizers such as melting point depressants, dispersants such as surfactants, color image stabilizers, antioxidants, light stabilizers and lubricants.

Further, a protective layer may be provided on the recording layer for the purpose of deformation of the surface of the recording layer due to heat, improvement of storage stability, prevention of sticking and the like. As the resin used for this protective layer, a resin having high heat resistance and mechanical strength is preferable, and for example, a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, a silicone resin or the like is used. If necessary, an undercoat layer may be provided between the recording layer and the support, and a backcoat layer may be provided on the surface of the support opposite to the surface on which the recording layer is formed.

[0035]

According to the reversible thermosensitive recording medium according to the invention described in claims 1 to 5, the basicity is relatively weaker than that of the color-developing agent acting at the time of erasing, and the leuco compound acts at the time of erasing to reduce the color. When the recording layer in the image forming state is subjected to a low-temperature heat treatment for decolorization, the decoloring auxiliary agent is mixed in the recording layer, and in addition to the action of the amino group of the color-developing and reducing agent, this decoloring Since the auxiliary agent also acts to remove hydrogen ions from the leuco compound,
The leuco compound at the heating site can be more completely ring-closed, and the decoloring property in the reversible thermosensitive recording medium can be improved.

On the other hand, when the recording layer in the image-erased state is subjected to high-temperature heat treatment for color development, since this treatment is heating for a short time, the recording layer at the treated portion is instantly solidified. Since the decoloring aid blended in the recording layer is relatively basic and weaker in decolorizing action on the leuco compound than the decolorizing agent acting at the time of decoloring, the presence of the decolorizing aid is a leuco compound. Does not affect the color developability of the ink, and because the decolorizing effect of the decoloring aid on the leuco compound is weak, the image forming state is maintained and the presence of the decoloring aid is recorded unless heat energy is applied. It does not affect the record keeping property of the layer.

Further, even when a leuco compound or a color-developing / reducing agent having a high solvent solubility is applied in the production of a reversible thermosensitive recording medium, the presence of the decoloring aid suppresses the coloring property of the leuco compound. It is also possible to avoid the "fog coloring phenomenon".

[0038]

EXAMPLES Examples of the present invention will be described in detail below. In addition, "part" in an Example has shown the weight part.

[Example 1] (Preparation of coating liquid for recording layer) 20 parts of crystal violet lactone (leuco compound)

[0040]

Embedded image Salt of bisphenolacetic acid and stearylamine (developing / reducing agent) 50 parts

[0041]

Embedded image Methacrylic resin (binder resin) 30 parts Stearic acid amide (sensitizer) 50 parts Amino-modified silicone oil (decoloring aid: Shin-Etsu Chemical Co., Ltd.) 5 parts Toluene 800 parts After thoroughly mixing the above compositions, disperse with a ball mill. A recording layer coating liquid was obtained.

This was coated on a white polyester sheet of 188 μm with a Mayer bar to give a coating thickness of 15 μm after drying.
The recording layer was applied so that An ultraviolet curable resin monomer was applied onto this recording layer using a Mayer bar and cured by irradiation with ultraviolet rays to form a protective layer having a film thickness of 2 μm to prepare a reversible thermosensitive recording medium.

Example 2 (Preparation of coating liquid for recording layer) 20 parts of 2- (2-chlorophenylamino) -6-diethylaminofluorane (leuco compound)

[0044]

[Chemical 3] Salt of stearyl gallate and stearylamine (developer) 60 parts

[0045]

[Chemical 4] Polyvinyl alcohol (binder resin) 30 parts Stearic acid amide (sensitizer) 30 parts Polyethylene glycol (decoloring aid) 5 parts Water 1000 parts A coating solution having the above composition is applied to a fine paper of 60 g / m ² on a Mayer bar. The recording layer was applied so that its weight after drying was 6 g / m ² . This was dried and then calendered to prepare a reversible thermosensitive recording medium.

[Example 3] (Preparation of coating liquid for recording layer) 2- (2-chlorophenylamino) -6-diethylaminofluorane (leuco compound) 20 parts Salt of bisphenolacetic acid and stearylamine (developing / reducing agent) 60 Parts methacrylic resin (binder resin) 30 parts stearic acid amide (sensitizer) 50 parts dibutyl maleate (decolorization aid) 7 parts toluene 750 parts After thoroughly mixing the above composition, disperse with a ball mill to coat recording layer. A liquid was obtained.

This was coated on a white polyester sheet of 188 μm with a Mayer bar so that the coating thickness after drying was 15 μm.
The recording layer was applied so that An ultraviolet curable resin monomer was applied onto this recording layer using a Mayer bar and cured by irradiation with ultraviolet rays to form a protective layer having a film thickness of 2 μm to prepare a reversible thermosensitive recording medium.

[Example 4] Except that 3 parts of polyether-modified silicone oil (decolorization aid) was applied instead of 5 parts of amino-modified silicone oil (decolorization aid: Shin-Etsu Chemical Co., Ltd.) This is almost the same as the reversible thermosensitive recording medium according to Example 1.

Example 5 The reversible process of Example 2 except that 3 parts of polyoxyethylene sorbitan monolaurate (decolorization aid) was applied instead of 5 parts of polyethylene glycol (decolorization aid). It is almost the same as the heat-sensitive recording medium.

Example 6 In place of 7 parts of dibutyl maleate (decoloring aid), distearyl phthalate (decoloring aid) 7 was used.
The reversible thermosensitive recording medium according to Example 3 is substantially the same as the reversible thermosensitive recording medium except that parts are applied.

[Comparative Example 1] The reversible thermosensitive recording medium according to Example 1 is substantially the same as the reversible thermosensitive recording medium except that an amino-modified silicone oil (decoloring aid: manufactured by Shin-Etsu Chemical Co., Ltd.) is not added.

[Comparative Example 2] This is almost the same as the reversible thermosensitive recording medium according to Example 2 except that polyethylene glycol (decolorization aid) is not added.

Comparative Example 3 The reversible thermosensitive recording medium according to Example 3 is substantially the same as the reversible thermosensitive recording medium except that dibutyl maleate (decolorization aid) is not added.

[Confirmation Test] Next, the reversible thermosensitive recording media according to Examples 1 to 6 and the reversible thermosensitive recording media according to Comparative Examples 1 to 3 were measured with a thermal printer at 0.3 m.
J / dot, pulse width 2.5 ms, ON / OFF printing energy conditions are used, and each printed recording medium is erased by pressing it for 1 second with a hot stamp plate heated to 100 ° C. The same printing and erasing operations were repeated.

Then, for each recording medium, the "background density", "erase rate", obtained in the printing / erasing operation,
The respective data of "color density" and "print storability" are shown in Table 1 below.

Each density in the table is a value obtained by measuring the optical reflection density with a Macbeth densitometer. The "erasure rate" is a value obtained by dividing the value obtained by subtracting the background density from the erase density by the value obtained by subtracting the background density from the color development density. Also, "print preservation"
Is the density residual ratio after 24 hours at room temperature after printing.

As can be seen from the comparison of Example 1 with Comparative Example 1, Example 2 with Comparative Example 2, and Example 3 with Comparative Example 3 in Table 1, each Example is different from each other. It can be confirmed that the erasing rate is increased by 3% to 6%.

Regarding the "print storability", Example 1 was 2% as compared with Comparative Example 1, and Example 2 was 1% as compared with Comparative Example 2.
%, But the value was slight, and it was not a value that poses a particular problem as a recording medium.

It was also confirmed that the reversible thermosensitive recording media according to Examples 4 to 6 had a good erasing rate as in the reversible thermosensitive recording media according to Examples 1 to 3.

[0060]

[Table 1]

[0061]

According to the inventions according to claims 1 to 5,
A recording layer in an image forming state, in which an erasing aid having a weaker basicity than that of a color-developing / reducing agent which acts at the time of erasing and which acts on a leuco compound at the time of erasing to reduce the color thereof is blended in the recording layer. When a low-temperature heat treatment for decoloring is applied to the leuco compound, the deionizing aid acts in addition to the action of the amino group of the color-developing and decoloring agent to remove hydrogen ions from the leuco compound, so that the leuco compound at the heating site is more completely removed. It is possible to close the ring.

On the other hand, when the recording layer in the image-erased state is subjected to a high temperature heating treatment for color development, this treatment is heating for a short time, so that the recording layer at the treated portion is instantly solidified. Since the decoloring aid blended in the recording layer is relatively basic and weaker in decolorizing action on the leuco compound than the decolorizing agent acting at the time of decoloring, the presence of the decolorizing aid is a leuco compound. Does not affect the color developability of the ink, and because the decolorizing effect of the decoloring aid on the leuco compound is weak, the image forming state is maintained and the presence of the decoloring aid is recorded unless heat energy is applied. It does not affect the record keeping property of the layer.

Therefore, there is an effect that the decoloring property in the reversible thermosensitive recording medium can be improved without lowering the recording property and the recording storability.

Further, even when a leuco compound or a color-developing / reducing agent having a high solvent solubility is applied in the production of a reversible thermosensitive recording medium, the presence of the decoloring aid suppresses the coloring property of the leuco compound. This has the effect of avoiding the "fogging and coloring phenomenon".

Claims (5)

[Claims] 1. A leuco compound having at least one of a phenolic hydroxyl group and a carboxyl group and having an amino group as a functional group or as a part of a salt compound and acting on the above leuco compound to develop or reduce the color thereof. In a reversible thermosensitive recording medium, in which a recording layer mainly composed of a color-developing / reducing agent and a binder is provided on a support, and the above-mentioned recording layer develops or erases color by controlling thermal energy, the color-developing / color-decreasing that acts during decoloring A reversible thermosensitive recording medium, characterized in that a decolorizing aid, which is relatively weaker in basicity than the agent and acts on a leuco compound at the time of decoloring to reduce the color thereof, is incorporated in the recording layer. 2. The reversible thermosensitive recording medium according to claim 1, wherein the decolorization aid is composed of a compound having a polysiloxane in the molecule. 3. The reversible thermosensitive recording medium according to claim 1, wherein the decolorizing aid is composed of a compound having a polyoxyethylene chain in the molecule. 4. The reversible thermosensitive recording medium according to claim 1, wherein the decoloring aid is composed of a carboxylic acid ester. 5. The decolorizing aid comprises at least two compounds selected from a compound having a polysiloxane in the molecule, a compound having a polyoxyethylene chain in the molecule, and carboxylic acid esters. The reversible thermosensitive recording medium according to claim 1, wherein