JPH091933A - Reversible thermal recording medium - Google Patents

Abstract

PURPOSE: To provide a reversible thermal recording medium for a density irregularity or contaminant due to erasing residue not to be evident by reducing the density difference between a color erased part and a skin part when the color developed image is erased in the medium utilizing the reaction of a color developing agent with a developer. CONSTITUTION: The reversible thermal recording medium comprises a recording layer containing electron donative coloring compound and electron acceptive coloring compound as main ingredients on a support, wherein the support is colored with dye or pigment.

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, electron-donating color-forming compounds (hereinafter referred to as
Thermosensitive recording media utilizing a color development reaction between a color former and an electron-accepting compound (hereinafter also referred to as a developer) are widely known, and include computer output, facsimile,
It is widely applied to automatic ticket vending machines, printers for scientific measuring machines, printers for CRT medical measurement, and the like. However, all of the conventional products have an irreversible color development, and cannot alternately repeatedly perform color development and color erasure.

Therefore, for example, in Japanese Utility Model Application Laid-Open No. 2-3876, which is applied to our application, image contrast is improved by using a support having a colored layer on the surface as a support for a reversible thermosensitive recording medium. However, the image formed on the reversible thermosensitive recording medium is not only a clouded image and not a colored image, but also uneven density and stains when the image on the reversible thermosensitive recording medium is erased. It is not a countermeasure against

On the other hand, according to the patent publication, there have been proposed some thermosensitive recording media which utilize the color-forming reaction between a color-developing agent and a color-developing agent to reversibly perform color-development. For example, Japanese Patent Application Laid-Open No. 60-193691 discloses a developer using a combination of gallic acid and phloroglucinol as a color developer. A colored body obtained by thermally coloring this 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 the recording medium water-resistant, and there is a problem in recording preservability, and there is a problem that a decoloring device for decoloring a color forming body becomes large. JP-A-61-237684 discloses a rewritable optical recording medium using a compound such as phenolphthalene, thymolphthalein or bisphenol as a developer. This can form a colored body by gradually cooling it after heating, and can be erased by heating the colored body once to a temperature higher than the coloring temperature and then rapidly cooling it. However, in the case of this recording medium, the steps of coloring and decoloring are complicated, and the decolored body obtained by decoloring the colored body still shows some coloring, and a color image with good contrast is obtained. Can not do.

[0005] JP-A-62-140881, JP-A-62-138568 and JP-A-62-1855.
No. 6 discloses a homogeneous solution of a color former, a developer and a carboxylic acid ester. It shows a completely colored state at a low temperature and a completely erased state at a high temperature, and can maintain the colored or erased state at an intermediate temperature between them. White characters (decolored) can be recorded on the background (colored). Therefore, in the case of this recording medium, since the recorded image is a negative image, its use is limited and
In order to retain the recorded image, it is necessary to retain the image within a specific temperature range. JP-A-2-188294 and JP-A-2-188293 disclose, as a developer, a salt of gallic acid and a higher aliphatic amine that reversibly perform a color developing action and a color reducing action, and bis (hydroxyphenyl). ) A salt of acetic acid or butyric acid and a higher aliphatic amine is used. This product can be colored by heat in a specific temperature range and decolorized by heating at a higher temperature.
Since the color developing action and the color reducing action occur competitively, it is difficult to thermally control these actions, and it is difficult to obtain a good image contrast. As described above, the conventional reversible thermosensitive recording medium utilizing the reaction between the color former and the developer contains various problems and is still unsatisfactory.

The present inventors previously used an organic phosphoric acid having a long-chain aliphatic group, a carboxyl compound or a phenol compound as a color developer, and by combining this with a leuco compound or the like as a color former, 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 lower than the coloring temperature. We proposed a reversible thermochromic composition that can be repeatedly formed and erased by changing the temperature, and a reversible thermosensitive recording medium containing the composition in a recording layer. (Japanese Patent Application No. 3-355078
Issue). The reversible thermosensitive recording medium proposed by the present inventors is a reversible thermosensitive recording medium having many advantages that are incomparable to conventional reversible thermosensitive recording media, but it develops an image formed by heating and melting. When the color is erased at a temperature lower than the temperature, the color is not completely erased, and a density difference (erased residue) occurs between the color and the background. It was found that this resulted in uneven density and appeared as stains.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a density difference between a decolored portion and a background portion when a colored image is erased in a reversible thermosensitive recording medium utilizing the reaction between a color former and a developer. An object of the present invention is to provide a reversible thermosensitive recording medium in which density unevenness due to the unerased residue is not noticeable.

[0008]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, a recording layer containing a color former, a color developer, and a binder as main components is provided, and a colored state is formed by heating and melting, and at the same time, heating to a temperature lower than the coloring temperature erases In a reversible thermosensitive recording medium that forms a color state, the support of the reversible thermosensitive recording medium is preliminarily colored with a dye or pigment of the same color as the color of the color image formed in the recording layer, and recording is performed thereon. It consists of forming a layer. The reversible thermosensitive recording medium produced in this manner provides a clear image during color development, and at the time of color erasure, it is difficult to distinguish the density difference from the background portion despite a slight unerased residue, It becomes difficult to see as stains due to uneven density.

With respect to the reversible thermosensitive recording medium of the present invention, the principle of coloring and erasing, that is, image formation and image erasing will be described with reference to the graph of FIG. The vertical axis of the graph represents the color density and the horizontal axis represents the temperature. The solid line 1 shows the image forming process by heating and the broken line 3 shows the image erasing process by heating. A is the density in the completely erased state, B is the density in the saturated coloring state when heated to a temperature of T ₁ or higher, C is the density at the temperature of T ₀ or lower in the completely colored state, and D
Indicates the concentration when erased by heating at a 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 record
It may be heated to a temperature of T ₁ or higher with a thermal head,
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. In addition,
The color density at the time of forming a recorded image increases with the temperature increase at a temperature of T ₁ or higher and reaches the saturation density at point B. 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, in the process of forming the recorded image, the recording is held up to C by the path of the solid line ABC. 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 behavior characteristics of the 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 deletion by the reversible thermosensitive recording medium of the present invention, in which 4 is a support and 5 is a 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 an image erasing heat source, such as a heating roller 8,
It is achieved by heating to a temperature between T _{0 and} T ₁ . In FIG. 2, 6 indicates a color image.

The color developer used in the present invention basically has a structure showing a color development ability capable of developing color in the molecule and an alkyl chain having 5 or more carbon atoms for controlling cohesive force between molecules. A compound having a structural part, which is an organic phosphoric acid or aliphatic carboxylic acid or phenol having an aliphatic group having 12 or more carbon atoms, or a metal salt of mercaptoacetic acid having an aliphatic group having 10 to 18 carbon atoms, or carbon It is an alkyl ester of caffeic acid having an alkyl group of several 5 to 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. Among the color developers used in the composition of the present invention shown above, particularly preferable are long-chain alkylphosphonic acid, long-chain α-hydroxy fatty acid, long-chain alkylthiomalic acid, long-chain alkylmalonic acid, etc. Is not limited to these.

The color former of the present invention is a colorless or light-colored dye precursor exhibiting an electron donating property, and is not particularly limited, and conventionally known ones, for example, triphenylmethanephthalide compound, fluorane compound, phenothiazine compound. A compound, a leuco auramine-based compound, an indolinophtalide-based compound, or the like is used. Specific examples of the developer and the color former used in the present invention are described in detail in JP-A-5-124360, JP-A-6-8624 and JP-A-6-24132.

The binder resin for the recording layer is not particularly limited, and any known binder resin can be used.
Specific examples of the binder resin, hydroxyethyl cellulose, hydroxypropyl cellulose, methoxy cellulose, carboxymethyl cellulose, methyl cellulose, cellulose acetate, gelatin, casein, starch, sodium polyacrylate, polyvinylpyrrolidone, polyacrylamide, polyvinyl chloride, poly Vinyl acetate,
Vinyl chloride-vinyl acetate copolymer, polystyrene, styrene copolymer, phenoxy resin, polyester, aromatic polyester, polyurethane, polycarbonate, polyacrylic acid esters, polymethacrylic acid esters, acrylic acid copolymer, maleic acid Examples thereof include copolymers, polyvinyl alcohol, chlorinated vinyl chloride resins, and mixtures of these resins. The role of the binder resin in the recording layer is to prevent the reversible thermochromic composition from aggregating due to repeated coloring / decoloring and to maintain the composition in a uniformly dispersed state. In particular, a binder resin having high heat resistance is preferable because the composition often agglomerates and becomes non-uniform when heat is applied during color development. It is considered that various properties of the binder resin have a great influence on the behavior of the thermochromic composition.

For recording on the reversible thermosensitive recording medium of the present invention, a color former and a developer are essential components. The color of the composition is
It is obtained by cooling a color former composition formed by heating, melting and mixing a developer and a color developer to room temperature. Since this color forming composition has a decoloring temperature region on the lower side than the melting temperature, rapid cooling is preferable for cooling to normal temperature while maintaining color development from the molten coloring state. When the temperature is gradually lowered, some color erasure occurs when passing through the color erasure 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 former 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 developer and the color former or the cooling conditions. The formation of such an aggregated structure acts between the long chain structure portion of the developer molecule forming the color former and the excess long chain structure portion of the developer molecule not forming the color former. It is presumed that cohesion is mainly acting. The formation of such an aggregated structure is related to the decoloring phenomenon of the color former composition.

The color former composition can be decolored by heating its color development state to a specific temperature range.
In this decoloring process, the aggregate structure of the color-developing state changes, and finally the developer molecules are separated and crystallized from the color-forming body composition to form crystals of the color developing agent alone, resulting in a stable decoloring 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.

The support of the reversible thermosensitive recording medium of the present invention comprises
Although it is possible to use those which have already been colored and sold, it is possible to obtain a support having a desired color and concentration by coloring a white or colorless transparent support with a dye or a pigment.

The colored support of the present invention loses the contrast of the color image when the recording medium is prepared in a state of being colored too dark, and when the coloring is less, the density difference between the decolored part and the background part is visually recognized. I can do it. The color density of the support of the present invention is 0.10 or more and less than 0.60, preferably 0.15 or more and less than 0.50, and the bluish color is measured by a Macbeth densitometer (RD-914). , 0.15
Or more and less than 0.80, preferably 0.20 or more, 0.70
Less, red system color is 0.12 or more and less than 0.70, preferably 0.15 or more and less than 0.50, yellow system color is 0.12 or more and less than 0.80, preferably 0.20 or more, 0.60 It is characterized in that it is within the range of less than.

The value of the color density is a common logarithm of the light absorptance expressed as a percentage of the spectrum light of the color. The concentration is 0.1. In actual measurement, the surface to be measured with extremely high whiteness is used as a standard, and the amount of absorbed light is measured by the instrument from the amount of reflected light. In any case, the difference in the light absorption rate (percentage) is particularly small in the low concentration range. The numerical value difference as the density difference is large, and therefore, it can be said that such a coloring density range of the support in the present invention is extremely narrow as a reflected light amount range. When coloring a colorless and transparent support, the maximum transmittance of each color is 30% as measured by a spectrophotometer.
It is characterized by being 80% or more and less than 80%, preferably 40% or more and less than 70%.

Various methods are conceivable for coloring a white or colorless and transparent support with a dye or a pigment, but the dye or the pigment is dissolved or dispersed in a binder resin and water or an organic solvent, and applied to the support. This can be easily achieved by As such a binder resin, those exemplified as the binder resin for the recording layer can be used. Further, dyes for coloring the support that can be used in the present invention, pigments that can be used heretofore known are azo, stilbene, xanthene, acridine, quinoline, azomethine, thiazole, indamine, Indophenol-based, azine-based, anthraquinone-based, indigo-based, phthalocyanine-based dyes / pigments, etc., but azo-based, anthraquinone-based, phthalocyanine-based, etc. are particularly preferred because the light resistance of these dyes / pigments themselves also becomes a problem. . Needless to say, these dyes / pigments may be used alone or in combination of two or more, and two or more dyes / pigments having different color tones may be used.

The reversible thermosensitive recording medium of the present invention comprises a support and a recording layer containing the above composition laminated on the support. Normally, a protective layer is laminated on the recording layer to improve durability.
The protective layer may be omitted. The support is paper, synthetic paper, a plastic film, a composite of these, glass, or the like, as long as it can hold the recording layer. The recording layer is
Any composition may be used as long as the above composition is present, and a developer and a color developer may be mixed and melted to form a film, which may be cooled to form a recording layer. However, it is usually preferable to sufficiently disperse the color developer and the color developer in the binder resin to form the recording layer, and a reversible thermosensitive recording medium having a long life can be obtained by this method. Further, in this case, the recording layer can be formed by a conventionally known method. That is, the color former and the color developer may be uniformly dispersed or dissolved in water or an organic solvent together with a binder resin, and this may be coated on a support and dried. In the reversible thermosensitive recording medium of the present invention, if necessary, various additives used in ordinary thermosensitive recording paper for the purpose of improving coating characteristics or recording characteristics,
For example, a dispersant, a surfactant, a polymeric cationic conductive agent,
Fillers, color image stabilizers, antioxidants, light stabilizers, lubricants and the like can be added to the recording layer.

The protective layer not only prevents the surface from being deformed or discolored by heat and pressure when heat is applied, but also improves chemical resistance, water resistance, abrasion resistance, head matching property and the like. Can also have. Therefore, it is preferable that the material for forming the protective layer is excellent in heat resistance and has high strength.
221087), polysiloxane graft polymer (JP-A-62-152550, JP-A-63-3).
No. 17385), a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin and the like are used, but those formed of an aqueous emulsion of a water-soluble polymer or a hydrophobic polymer compound may be used. By forming such a protective layer, heat resistance is improved as described above, and an organic solvent, a plasticizer, an oil,
The resistance against contact with sweat, water, etc. is also increased, and it is possible to obtain a recording medium capable of repeating image formation and erasing without problems even in a bad environment. Further, by containing a light stabilizer in the protective layer, a recording medium having significantly improved light resistance of images and background can be obtained, and addition of a high molecular cationic conductive agent enables antistatic property, and further the protective layer By adding an organic or inorganic filler and a lubricant to the above, sticking caused by contact with a thermal head or the like can be prevented, and a thermal recording medium having high reliability and head matching can be obtained. The protective layer may be formed by uniformly dispersing or dissolving the components of the protective layer with water or an organic solvent, and uniformly coating and drying the component on the recording layer, and the protective layer has a thickness of 0.
It is preferably about 5 to 10 μm.

In the reversible thermosensitive recording medium of the present invention, an undercoat layer may be provided between the support and the recording layer, if necessary. The undercoat layer is installed for the purpose of improving the heat insulation, improving the adhesion between the support and the recording layer, and improving the resistance of the support to the solvent when creating the recording layer.It is installed in consideration of the type of support. You can determine whether or not. One of the important roles of the undercoat layer is to improve heat insulation,
This is to make the applied heat energy useful for forming a heat record and erasing heat without waste, and by providing an adiabatic layer, coloring and erasing can be sharply performed. To form an undercoat layer for the purpose of heat insulation, fine hollow particles made of an organic or inorganic material may be applied onto a support, and specifically, it may be formed of glass or ceramics, plastic, or the like. A fine hollow body having a particle size of about 10 to 50 μm may be well dispersed in a solvent together with a binder resin, and uniformly coated and dried on a support. It should be noted that the applied heat energy can be saved by using a heat insulating support instead of providing the heat insulating layer, and a plastic film, synthetic paper or the like is used as the heat insulating support.

The formation of a recorded image is not particularly limited by a hot pen, a thermal head, laser heating, etc. depending on the purpose of use. Similarly, for erasing recorded images, heating rollers, sheet heating elements,
There is no particular limitation as long as the temperature conditions for erasing, such as a constant temperature bath, warm air, and a thermal head, are provided. It is also possible to form a recorded image by another thermal head set at the recording temperature while erasing the recorded image by the thermal head set at the erasing temperature.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, all parts and percentages are based on weight.

(Coloring of Support) As a support, 100 μm
m white PET film (Toray Industries, Inc., Lumirror E20) and 100 μm colorless transparent PET film (Toray Inc., Lumirror T60) were coated with the following composition with a wire bar to a thickness of about 1
The reversible thermosensitive recording medium support was coated and dried to have a thickness of about 3 μm and dried to give a black tint. 1) 10% PVA aqueous solution 100 parts Dye (Direct Black 168) 0.05 part In the same manner, with respect to the composition of each of the following colors, a support for a reversible thermosensitive recording medium was prepared in the same manner as described above. . 2) 10% PVA aqueous solution 100 parts Dye (Direct Blue 199) 0.07 parts 3) 10% PVA aqueous solution 100 parts Dye (Direct Red 254) 0.07 parts 4) 10% PVA aqueous solution 100 parts Dye (Direct Yellow 86) The supports of the colored reversible thermosensitive recording medium produced by 0.1 parts or more are designated by the symbols a to p, and the supports which are not colored are designated as W and Y for comparison. These are shown in Table 1.

[0028]

[Table 1]

(Recording Layer) The following recording layer compositions were pulverized and dispersed by a ball mill so that the particle diameter was 2 to 4 μm.
A reversible thermosensitive recording medium was prepared by coating and drying the colored supports a to p and the unsupported comparative supports W and Y prepared in the above examples with a wire bar to a thickness of about 6 μm. did. A 2- (o-chloroanilino) -6-dibutylaminofluorane 3 parts Octadecylphosphonic acid 10 parts Vinyl chloride / vinyl acetate copolymer, (Union Carbide Co., VYHH) 10 parts Toluene 45 parts Methyl ethyl ketone 45 parts B 3, 6-bis (diphenylamino) fluorane 3,5 parts Eicosylthiomalic acid 11 parts Acrylic resin (BR-107 manufactured by Mitsubishi Rayon Co., Ltd.) 10 parts Toluene 45 parts Methyl ethyl ketone 45 parts C2-Methyl-6- {N-ethyl -N- (p-tolyl)} fluorane 3 parts Eicosylphosphonic acid 10 parts Urethane resin (Nippon Polyurethane Co., P-26) 7 parts Toluene 45 parts Methyl ethyl ketone 48 parts D 3-Chloro-6- (N-cyclohexyl) fluoran 3 parts octadecylphosphonic acid 10 parts vinyl chloride Le / vinyl acetate copolymer (VYHH) 45 parts Methyl ethyl ketone 45 parts 10 parts Toluene

Reversible thermosensitive recording media were prepared by combining each of the recording layer compositions described above with the colored support to give Examples 1 to 16. In addition, reversible thermosensitive recording media were prepared by combining the recording layer composition with a support which was not colored, and named Comparative Examples 1 to 8. The following tests were conducted on the above reversible thermosensitive recording media. Macbeth densitometer (RD-91
Measured in 4). (For the transparent support, the maximum value of the transmittance was measured with a spectrophotometer (UV-3000, manufactured by Shimadzu Corporation) for the transparent support. 8 dots / m for the samples of Examples and Comparative Examples
pulse width of 0.6 with a printing device that uses a m thermal head
printing under the conditions of ms, printing energy of 23.2 mJ / mm ² , and the image density is determined by Macbeth densitometer (RD-914).
It was measured at. The color-developed image printed in 1. was put in a constant temperature bath set at 70 ° C. for 3 minutes to erase the image, and the density was measured with a Macbeth densitometer (RD-914). The difference between the background density and the decolorization density was determined as the effect. The sample was visually evaluated. ◯: It is difficult to distinguish the erased part and the background part of the image. Δ: The decolored part and the background part of the image are slightly distinguishable. X: The decolored part and the background part of the image can be distinguished. The results are shown in Table 2.

[0031]

[Table 2]

[0032]

As is clear from the above detailed and specific description, the reversible thermosensitive recording medium using the colored support of the present invention can obtain a vividly colored image and especially when the image is erased. The difference in density between the decolored portion and the background portion is small, and an excellent effect that density unevenness and stains are difficult to distinguish is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the coloring and decoloring principles of a reversible thermosensitive recording medium of the present invention with a temperature-coloring density relationship graph.

FIG. 2 is a diagram illustrating an image forming step and an image erasing step.

[Explanation of symbols]

 1 Image forming process by heating 2 Image fixing process by cooling 3 Image erasing process by heating 4 Support 5 Reversible thermosensitive recording layer 6 Colored image 7 Thermal head 8 Heating roller A Completely erased state of image B Saturated colored state C Completely colored state D heating erased state

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[Procedure amendment]

[Submission date] September 18, 1995

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Front Page Continuation (72) Inventor Keiji Taniguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Kyoji Tsutsui 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Fumio Kawamura 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (6)

[Claims] 1. A reversible thermosensitive recording medium comprising a support and a recording layer containing an electron-donating color-forming compound and an electron-accepting compound as main components, the support being colored with a dye or a pigment. A reversible thermosensitive recording medium characterized in that 2. The support according to claim 1, which is colored with a blackish color and has a density of 0.10 as measured by a Macbeth densitometer.
A reversible thermosensitive recording medium characterized in that it is not less than 0.60. 3. The support according to claim 1 is colored with a blue color and has a density of 0.15 as measured by a Macbeth densitometer.
A reversible thermosensitive recording medium characterized by being not less than 0.80. 4. The support according to claim 1, which is colored with a reddish color and has a density of 0.12 as measured by a Macbeth densitometer.
A reversible thermosensitive recording medium characterized in that it is not less than 0.70. 5. The support according to claim 1 is colored with a yellowish color, and the density is 0.12 as measured by a Macbeth densitometer.
A reversible thermosensitive recording medium characterized by being not less than 0.80. 6. The reversible thermosensitive recording medium according to claim 1, wherein the support has a maximum transmittance of 30% or more and less than 80% as measured by a spectrophotometer.