JPH0958142A - Cleaning method for thermal recording media - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for efficiently cleaning a reversible thermosensitive recording material, improving the durability of the material, and repeating recording and erasing over a long period of time. In a method for cleaning the surface of a reversible thermosensitive recording medium having a recording layer containing an electron-donating color-developing compound and an electron-accepting compound, the cleaning means heats the recording material at a temperature substantially equal to the temperature for erasing recorded information A method for cleaning a reversible thermosensitive recording medium, characterized in that the reversible thermosensitive recording medium is cleaned at the same time as erasing information by the cleaning means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a thermal recording medium utilizing a reversible color development reaction between an electron-donating color-forming compound and an electron-accepting compound, which is used for a long period of time. And a cleaning method for a reversible thermosensitive recording material having excellent durability.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording medium 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) has been widely known. It is widely applied to the output of electronic calculators, facsimiles, automatic ticket vending machines, and plotters of scientific measuring instruments. However, the color development of all conventional products is irreversible, and the color development and the color erasing cannot be alternately repeated. On the other hand, according to the patent publication, a reversible color developing and erasing method is also proposed, and for example, a combination of gallic acid and phloroglucinol is used as a color developing agent. JP-A-61-237684, which uses a compound such as phenolphthalein and thymolphthalein as a color developer, and JP-A-62-123684 in which a homogenous solution of a color former and a carboxylic acid ester is contained in a recording layer.
JP-A No. 138555, JP-A No. 62-138568, and JP-A No. 62-140881. JP-A 2-18 using a salt of gallic acid and a higher aliphatic amine as a developer.
No. 8294, Bis (hydroxyphenyl) as a developer
JP-A-2-188293, which uses a salt of acetic acid or butyric acid and a higher aliphatic amine, is disclosed. When such a reversible thermosensitive recording material is repeatedly used, it is possible that dust or the like adheres to the surface of the reversible thermosensitive recording material due to heat or pressure of the thermal head, and accurate recording and its erasing cannot be performed. Can be seen. Several measures have been proposed to deal with such a problem. For example, a method of cleaning by providing a cleaning solid having a card surface connected to the main body of the apparatus with attachment / detachment itself (Japanese Patent Laid-Open No. 296981).
No. 3,296,982), a method of erasing an image by immersing a reversible thermosensitive recording material in hot water in a liquid bath and heating it, though not expecting a direct cleaning effect ( JP-A-57-89992) and the like are known.

[0003]

However, according to these devices / methods, the reversible thermosensitive recording material cannot always be efficiently and repeatedly used over a long period of time. The present invention solves the above-mentioned drawbacks, and (1) eliminates printing unevenness and erasing unevenness due to slag, dust, etc. adhering to the surface of a reversible thermosensitive recording material in all shapes such as card shape, sheet shape, belt shape, 2) by making the printed image uniformly cloudy or transparent, and at the same time washing, and (3) improving the durability of the reversible thermosensitive recording material,
The present invention provides a method for cleaning a reversible thermosensitive recording material, which enables efficient and long-term recording / erasing. In particular, the present invention provides a method for cleaning a heat-sensitive recording material having oil stains such as cutting oil and lubricating oil attached.

[0004]

As a result of intensive studies, the inventors of the present invention have found that the above-mentioned problems can be solved by heating the cleaning means at a temperature substantially equal to the temperature at which recorded information is erased. It was That is, the present invention provides the following (1)
~ (6).

(1) In a method of cleaning the surface of a reversible thermosensitive recording medium having a recording layer containing an electron-donating color-developing compound and an electron-accepting compound, the cleaning means has a temperature at which recorded information is erased. A method for cleaning a reversible thermosensitive recording medium, wherein the reversible thermosensitive recording medium is heated substantially at the same time, and the reversible thermosensitive recording medium is cleaned almost simultaneously with erasing information by the cleaning means. (2) The reversible thermosensitive recording medium cleaning method according to (1), wherein the cleaning method is wet or dry. (3) The reversible thermosensitive recording cleaning method according to (2), wherein the dry cleaning is performed with a cleaning roller, a cleaning brush, a cleaning belt or a cleaning block.

(4) The cleaning roller, cleaning brush, cleaning belt or cleaning block used for the dry cleaning is formed of one or more of a fiber cloth, a non-woven cloth, an adhesive and an abrasive. ) A method for cleaning a reversible thermosensitive recording medium as described above. (5) The reversible thermosensitive recording medium cleaning method according to (3), wherein the wet cleaning is cleaning by immersion in a liquid bath or cleaning with a water jet, a cleaning roller, a cleaning brush, a cleaning belt or a cleaning block. (6) A cleaning roller, a cleaning brush, a cleaning belt or a cleaning block in the wet cleaning, which is a fiber cloth, a non-woven cloth, a belt on which a belt made of a water-absorbent material is wound or a wound roll, and a block, which moisten the droplets. The method for cleaning a reversible thermosensitive recording medium as described in (5) above, wherein a part or all of itself, or the whole thereof, is in a liquid bath, and the liquid is supplied to the liquid cleaning portion at any time.

Next, details of the thermal recording medium of the present invention will be described. The reversible thermosensitive recording medium used in the present invention develops color instantaneously by heating, and its color-developed state is stable even at room temperature, but the recording layer in the color-developed state is decolored by heating below the color-developing temperature and its decolorized state. It exists stably even in the state. The principle of coloring and erasing of the reversible thermosensitive recording medium used in the present invention, that is, the principle of 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 development temperature, the horizontal axis represents the temperature, the solid line 1 represents the image forming process by heating, and the broken line represents the image erasing process by heating. A is the concentration in the completely erased state, B is the concentration in the saturated coloring state when heated to a temperature of T1 or higher, C is the concentration at the temperature of T0 or lower in the saturated coloring state, and D is between T0 and T1. It shows the concentration when erased by heating at the temperature.

The reversible thermosensitive recording medium to which the present invention is applied is in a colorless state (A) at a temperature of T0 or lower. To perform recording, heating with a thermal head or the like to a temperature of T1 or higher is performed, and color development (B) is performed to form a recorded image. Even if the temperature is returned to T0 or lower 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, it is sufficient to heat the formed image to a temperature between T0 and T1 which is lower than the coloring temperature, resulting in a colorless state (D). This state is maintained as it is even if the temperature is returned to T0 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. The process of erasing the recorded image is
At A, the erased state is maintained. The behavior characteristics of the formation and erasure of the recorded image are reversible and can be repeated many times. The reversible thermosensitive recording medium of the present invention contains a color former and a developer as essential components. The color development of the reversible thermosensitive recording medium of the present invention is obtained by cooling the color-forming component formed by the eutectic reaction of the developer and the color-forming agent constituting the reversible thermosensitive recording layer by heating to room temperature. It is a thing. This color former composition has an erasing temperature region on the control side of the melting temperature, and therefore can be obtained by cooling to room temperature while maintaining the color development from the molten color development state. 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 quench rapidly when cooling from the melt-colored state to room temperature while maintaining the color development. With slow cooling, some color disappears when passing through the color-erasing temperature region, 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 rapidly cooled from the molten state contains, in addition to the color former molecules, a developer molecule and a color former molecule that are not directly involved in the formation of the color former. In the reversible thermosensitive recording medium of the present invention, the colorant 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 of the color developer and the color developer, the amount ratio, and the cooling conditions. The main reason for forming such an aggregate structure is the alkyl chain structure part of the developer molecule forming the color former and the excess alkyl chain structure part of the developer molecule not forming the color former. It is presumed that some bonding force is working between them. 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-developed state to a specific temperature range. In this decoloring process, the aggregate structure of the color developing state changes, and eventually the developer molecules are separated and crystallized from the color former composition to form crystals of the developer alone, resulting in a stable decolored state. Confirmed by X-ray. As described above, in the reversible thermosensitive recording medium of the present invention, it is clear that the alkyl chain portion plays a large role in the formation of the color-developed state and the decoloring process thereof, which is the reversible thermosensitive recording medium of the present invention. It is a characteristic of the formed colorant composition. Therefore, the decolorization temperature can be controlled by the length of the alkyl chain portion of the color developer, and the longer the chain length, the more often the color development and decolorization temperature shift to the high temperature side. This is because the cohesion and mobility of the developer molecules change depending on the length of the portion.

The reversible thermochromic composition formed in the recording layer of the recording medium used in the present invention is basically a composition obtained by combining the color developer and the color developer having an alkyl chain structure portion. There are preferred color formers for individual developers. The combination of the color developing agent, the color developing agent and the color developing agent used in this reversible thermochromic composition occurs when the coloring state composition obtained by heating both of them to a melting temperature or higher is heated to a temperature lower than the melting temperature. It is appropriately selected depending on the characteristics such as easiness of erasing (erasability) and the color tone of the coloring state. Among these, 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 color-developed state composition obtained by the combination. This exothermic peak corresponds to the decoloring phenomenon that characterizes the composition, and serves as a criterion for selecting a combination having a good decoloring property. In the reversible thermosensitive recording medium used in the present invention, the third substance may be present in the reversible thermosensitive recording layer.
Coloring behavior can be maintained. The color former used in the present invention is a compound exhibiting an electron donating property, and is applied alone or as a mixture of two or more kinds, but it is a colorless or light-colored dye precursor per se and is not particularly limited and is conventionally known one. , For example, triphenylmethanephthalide type, triallylmethane type, fluorane type, phenothidian type, thioferolane type, xanthene type, indophthalyl type, spiropyran type, azaphthalide type, chromenopyrazole type, methine type, rhodamine anilinolactam type Leuco compounds such as rhodamine lactams, quinazolines, diazoxanthenes, and bislactones are preferably used. Examples of such compounds are shown below, but the present invention is not limited thereto.

2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-
(Di-n-butylamino) fluorane, 2-anilino-
3-methyl-6- (Nn-propyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N
-Isopropyl-N-methylamino) fluoran, 2-
Anilino-3-methyl-6- (N-isobutyl-N-methylamino) fluoran, 2-anilino-3-methyl-
6- (Nn-amyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-sec-butyl-N-ethylamino) fluoran, 2-anilino-
3-methyl-6- (Nn-amyl-N-ethylamino) fluoran, 2-anilino-3-methyl-6- (N
-Iso-amyl-N-ethylamino) fluoran, 2
-Anilino-3-methyl-6- (Nn-propyl-N
-Isopropylamino) fluoran, 2-anilino-3
-Methyl-6- (Nn-propyl-N-isopropylamino) fluoran, 2-anilino-3-methyl-6
(N-cyclohexyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-ethyl-p
-Toluidino) fluorane, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluorane, 2
-(M-Trichloromethylanilino) -3-methyl-6
-Diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-
Methyl-6- (N-cyclohexyl-N-methylamino) fluoran, 2- (2,4-dimethylanilino)-
3-methyl-6-diethylaminofluorane, 2- (N
-Ethyl-p-toluidino) -3-methyl-6- (N-
Ethylanilino) fluorane, 2- (N-methyl-p-
Toluidino) -3-methyl-6- (N-propyl-p-
Toluidino) fluoran, 2-anilino-6- (N-n
-Hexyl-N-ethylamino) fluoran, 2- (o
-Chloroanilino) -6-diethylaminofluoran,
2- (o-bromoanilino) -6-diethylaminofluoran, 2- (o-chloroanilino) -6-dibutylaminofluoran, 2- (o-fluoroanilino) -6-dibutylaminofluoran, 2- (m-toluene) Fluoromethylanilino) -6-diethylaminofluoran, 2-
(P-acetylanilino) -6- (Nn-amyl-N
-N-butylamino) fluoran, 2-benzylamino-6- (N-ethyl-p-toluidino) fluoran, 2
-Benzylamino-6- (N-methyl-2,4-dimethylanilino) fluoran, 2-benzylamino-6-
(N-ethyl-2,4-dimethylanilino) fluoran, 2-dibenzylamino-6- (N-methyl-p-toluidino) fluoran, 2-dibenzylamino-6
(N-ethyl-p-toluidino) fluoran, 2- (di-p-methylbenzylamino) -6- (N-ethyl-p
-Toluidino) fluoran, 2- (α-phenylethylamino) -6- (N-ethyl-p-toluidino) fluoran, 2-methylamino-6- (N-methylanilino)
Fluorane, 2-methylamino-6- (N-ethylanilino) fluorane, 2-methylamino-6- (N-propylanilino) fluorane, 2-ethylamino-6-
(N-methyl-p-toluidino) fluoran, 2-methylamino-6- (N-methyl-2,4-dimethylanilino) fluoran, 2-ethylamino-6- (N-methyl-2,4-dimethyl Anilino) fluoran, 2-dimethylamino-6- (N-methylanilino) fluoran, 2
-Dimethylamino-6- (N-ethylanilino) fluoran, 2-diethylamino-6- (N-methyl-p-toluidino) fluoran, 2-diethylamino-6- (N
-Ethyl-p-toluidino) fluoran, 2-dipropylamino-6- (N-methylanilino) fluoran, 2
-Dipropylamino-6- (N-ethylanilino) fluoran, 2-amino-6- (N-methylanilino) fluoran, 2-amino-6- (N-ethylanilino) fluoran, 2-amino-6- (N-propyl Anilino) fluoran, 2-amino-6- (N-methyl-p-toluidino) fluoran, 2-amino-6- (N-ethyl-p
-Toluidino) fluoran, 2-amino-6- (N-propyl-p-toluidino) fluoran, 2-amino-6
-(N-methyl-p-ethylanilino) fluoran, 2
-Amino-6- (N-ethyl-p-ethylanilino) fluoran, 2-amino-6- (N-propyl-p-ethylanilino) fluoran, 2-amino-6- (N-methyl-2,4-dimethylaniline) Rino) fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-propyl-2,4-
Dimethylanilino) fluoran, 2-amino-6- (N
-Methyl-p-chloroanilino) fluoran, 2-amino-6- (N-ethyl-p-chloroanilino) fluoran, 2-amino-6- (N-propyl-p-chloroanilino) fluoran, 2,3-dimethyl-6 -Dimethylaminofluoran, 3-methyl-6- (N-ethyl-p-
Toluidino) fluoran, 2-chloro-6-diethylaminofluoran, 2-bromo-6-diethylaminofluoran, 2-chloro-6-dipropylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 3-bromo -6-cyclohexylaminofluoran, 2-chloro-6- (N-ethyl-N-isoamylamino) fluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-chloro-6
-Diethylaminofluoran, 2- (o-chloroanilino) -3-chloro-6-cyclohexylaminofluoran, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluoran, 2- (2 , 3-Dichloroanilino) -3-chloro-6-diethylaminofluoran, 1,2-benzo-6-diethylaminofluoran, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluoran, 1, 2-benzo-6-dibutylaminofluoran, 1,2-benzo-6- (N-ethyl-N-cyclohexylamino) fluoran, 1,2-
Benzo-6- (N-ethyl-toluidino) fluoran,
Other.

Specific examples of other color formers preferably used in the present invention are as follows. 2-anilino-3-methyl-6- (N-2-ethoxypropyl-N
-Ethylamino) fluoran, 2- (p-chloroanilino) -6- (Nn-octylamino) fluoran, 2
-(P-chloroanilino) -6- (Nn-partimylamino) fluoran, 2- (p-chloroanilino) -6
-(Di-n-octylamino) fluoran, 2-benzoylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (o-methoxybenzoylamino) -6
(N-ethyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6-diethylaminofluoran, 2-dibenzylamino-4-methoxy-6- (N
-Methyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethylamino)
-4-Methyl-6-diethylaminofluorane, 2-
(P-Toluidino) -3- (t-butyl) -6- (N-
Methyl-p-toluidino) fluoran, 2- (o-methoxycarbonylanilino) -6-diethylaminofluoran, 2-acetylamino-6- (N-methyl-p-toluidino) fluoran, 3-diethylamino-6- ( m
-Trifluoromethylanilino) fluoran, 4-methoxy-6- (N-ethyl-p-toluidino) fluoran, 2-ethoxyethylamino-3-chloro-6-dibutylaminofluoran, 2-dibenzylamino-4 -Chloro-6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethylamino) -4-chloro-
6-diethylaminofluoran, 2- (N-benzyl-
p-Trifluoromethylanilino) -4-chloro-6-diethylaminofluoran, 2-anilino-3-methyl-
6-pyrrolidinofluoran, 2-anilino-3-chloro-6-pyrrolidinofluoran, 2-anilino-3-methyl-6- (N-ethyl-N-tetrahydrofurfurylamino) fluoran, 2-mesidino- 4 ', 5'-benzo-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6-pyrrolidinofluoran, 2- (α-naphthylamino) -3,4- Benzo-4′-bromo-6- (N-benzyl-N-cyclohexylamino) fluoran, 2-piperidino-6-diethylaminofluoran, 2- (Nn-propyl-p-trifluoromethylanilino) -6 -Morpholinofluoran, 2- (di-N-p-chlorophenyl-methylamino) -6-pyrrolidinofluoran, 2- (Nn-propyl-m-trifluorome Ruanirino) -6-morpholinophenyl fluoran, 1,2-benzo-6- (N-ethyl -
Nn-octylamino) fluorane, 1,2-benzo-6-diallylaminofluorane, 1,2-benzo-6
-(N-ethoxyethyl-N-ethylamino) fluoran, benzoleucomethylene blue, 2- [3,6-bis (diethylamino)]-6- (o-chloroanilino) xanthyl benzoate lactam, 2- [3,6- Bis (diethylamino)]-9- (o-chloroanilino) xanthylbenzoic acid lactam, 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthaly (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, 3,6-bis (dimethylamino) fluorene Spiro (9,3 ')-
6'-dimethylaminophthalide, 6'-chloro-8'-
Methoxy-benzoindolino-spiropyran, 6'-bromo-2'-methoxy-benzoindolino-spiropyran and the like.

Next, the color developer used in the present invention is an electron-accepting compound, and various conventionally known electron-accepting color developers can be used. More preferably, however, in the present invention,
It is an electron-accepting developer containing in its molecule a long-chain alkyl group shown in Japanese Patent Application No. 3-355078. For example, carbon number 12
Organic phosphoric acid compounds, aliphatic carboxylic acid compounds, and phenol compounds having the above aliphatic groups, or C10 to C1
Examples thereof include a metal salt of mercaptoacetic acid having an aliphatic group having 8 carbon atoms, an alkyl ester of caffeic acid having an alkyl group having 5 to 8 carbon atoms, and an acidic phosphoric acid ester having an aliphatic group having 16 or more carbon atoms. The aliphatic group includes a linear or branched alkyl group and alkenyl group, and may have a substituent such as a halogen, an alkoxy group and an ester. Hereinafter, specific examples of the developer will be described. (A) Organic phosphoric acid compound A compound represented by the following general formula (1) is preferably used.

[0014]

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(R ₁ represents a linear alkyl group having 16 to 24 carbon atoms) 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 organic phosphoric acid compound, α-hydroxyalkylphosphonic acid represented by the following general formula (2) is also preferably used.

[0016]

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(However, R ₂ is an aliphatic group having 11 to 29 carbon atoms.) When the α-hydroxyalkylphosphonic acid represented by the general formula (2) is specifically shown, α-hydroxydodecylphosphonic acid, α-hydroxytetradecylphosphonic acid, α-
Examples include hydroxyhexadecylphosphonic acid, α-hydroxyoctadecylphosphonic acid, α-hydroxyeicosylphosphonic acid, α-hydroxydocosylphosphonic acid, and α-hydroxytetracosylphosphonic acid. As the organic phosphoric acid compound, an acidic organic phosphoric acid ester represented by the following general formula (3) is also used.

[0018]

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(In the formula, R ₃ represents an aliphatic group having 16 or more carbon atoms, and R ₄ represents a hydrogen atom or an aliphatic group having 1 or more carbon atoms.) Acidic organic compound represented by the general formula (3) Specific examples of the phosphate ester, dihexadecyl phosphate, dioctadecyl phosphate, dieicosyl phosphate, didocosyl phosphate, monohexadecyl phosphate,
Monooctadecyl phosphate, monoeicosyl phosphate, monodocosyl phosphate, methyl hexadecyl phosphate, methyl octadecyl phosphate, methyl eicosyl phosphate, methyl docosyl phosphate, amyl hexadecyl phosphate, octyl hexadecyl phosphate, lauryl hexadecyl phosphate, etc. Can be

(B) Aliphatic Carboxylic Acid Compound [alpha] -hydroxy fatty acids represented by the following general formula (4) are preferably used. R ₅ —CH (OH) —COOH (4) (where R ₅ represents an aliphatic group having 12 or more carbon atoms). Examples of the α-hydroxyaliphatic carboxylic acid compound represented by the general formula (4) include: The following are mentioned.
α-hydroxydecanoic 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 and substituted with a halogen element, at least in the α-position or β-position.
Those having a halogen element in the carbon at the position are also preferably used. Specific examples of such a compound include the followings. 2-bromohexadecanoic acid, 2-bromoheptadecanoic acid, 2-bromooctadecanoic acid, 2-bromoeicosanoic acid, 2-bromodocosanoic acid, 2-bromotetracosanoic acid, 3-bromooctadecanoic acid, 3-bromoeicosanoic acid 2,2-dibromooctadecanoic acid, 2-fluorododecanoic acid, 2-fluorotetradecanoic acid, 2-fluorohexadecanoic acid, 2-fluorooctadecanoic acid, 2-fluoroeicosanoic acid, 2-
Fluorodocosanoic acid, 2-iodohexadecanoic acid, 2-
Iodooctadecanoic acid, 3-iodohexadecanoic acid, 3
-Iodooctadecanoic acid, perfluorooctadecanoic acid and the like. As the aliphatic carboxylic acid, an aliphatic carboxylic acid compound having an aliphatic group having 12 or more carbon atoms having an oxo group in the carbon, at least the carbon at the α-position, the β-position or the γ-position is an oxo group Are preferably used. Specific examples of such compounds include, for example, the following.

2-oxododecanoic acid, 2-oxotetradecanoic acid, 2-oxohexadecanoic acid, 2-oxooctadecanoic acid, 2-oxoeicosanoic acid, 2-oxotetracosanoic acid, 3-oxododecanoic acid, 3-oxo Tetradecanoic acid, 3-oxohexadecanoic acid, 3-oxooctadecanoic acid, 3-oxoeicosanoic acid, 3-oxotetracosanoic acid, 4-oxohexadecanoic acid, 4-oxooctadecanoic acid, 4-oxodocosanoic acid and the like. As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (5) is also preferably used.

[0023]

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(Wherein R ₆ represents an aliphatic group having 12 or more carbon atoms, X represents an oxygen atom or a sulfur atom, and n
Represents 1 or 2. ) Specific examples of the dibasic acid represented by the general formula (5) include:
For example, the following are mentioned. Dodecyl malate, tetradecyl malate, hexadecyl malate, octadecyl malate, eicosyl malate, docosyl malate, tetracosyl malate, dodecyl thiomalate, tetradecyl thiomalate, hexadecyl thiomalate,
Octadecylthiomalic acid, eicosylthiomalic acid,
Docosylthiomalic acid, tetracosylthiomalic acid, dodecyldithiomalic acid, tetradecyldithiomalic acid,
Eicosyldithiomalic acid, docosyldithiomalic acid,
Tetracosyldithiomalic acid, etc. As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (6) is also preferably used.

[0025]

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(However, R ₇ , R ₈ and R ₉ represent hydrogen or an aliphatic group, at least one of which is an aliphatic group having 12 or more carbon atoms.) Two represented by the general formula (6). Specific examples of the basic acid include:
For example, the following may be mentioned. Dodecyl butane diacid, tridecyl butane diacid, tetradecyl butane diacid, pentadecyl butane diacid, octadecyl butane diacid, eicosyl butane diacid, docosyl butane diacid, 2,
3-dihexadecyl butane diacid, 2,3-dioctadecyl butane diacid, 2-methyl-3-dodecyl butane diacid,
2-Methyl-3-tetradecylbutanedioic acid, 2-methyl-3-hexadecylbutanedioic acid, 2-ethyl-3-dodecylbutanedioic acid, 2-propyl-3-dodecylbutanedioic acid, 2-octyl- 3-hexadecyl butanedioic acid, 2-
Tetradecyl-3-octadecylbutanediacid and the like. As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (7) is also preferably used.

[0027]

[Chemical 6]

(However, R ₁₀ and R ₁₁ represent hydrogen or an aliphatic group, at least one of which is an aliphatic group having 12 or more carbon atoms.) Of the dibasic acid represented by the general formula (7), As a specific example,
For example, the following are mentioned. Dodecylmalonic acid, tetradecylmalonic acid, hexadecylmalonic acid, octadecylmalonic acid, eicosylmalonic acid, docosylmalonic acid, tetracosylmalonic acid, didotecilmalonic acid, ditetradecylmalonic acid, dihexadecylmalonic acid, dioctadecylmalonic acid Acid, dieicosylmalonic acid, didocosylmalonic acid, methyloctadecylmalonic acid, methyldocosylmalonic acid, methyltetracosylmalonic acid, ethyloctadecylmalonic acid, ethyleicosylmalonic acid, ethyldocosylmalonic acid, ethyltetracosylmalonic acid Malonic acid etc. As the aliphatic carboxylic acid compound, a dibasic acid represented by the following general formula (8) is also preferably used.

[0029]

[Chemical 7]

(However, R ₁₂ represents an aliphatic group having 12 or more carbon atoms, n represents 0 or 1, m represents 1, 2 or 3, and when n is 0, m is 2 or 3. Yes,
When n is 1, m represents 1 or 2. ) Specific examples of the dibasic acid represented by the general formula (8) include:
For example, the following may be mentioned. 2-dodecyl-
Pentanedioic acid, 2-hexadecyl-pentanedioic acid, 2-
Octadecyl pentanedioic acid, 2-eicosyl-pentanedioic acid, 2-docosyl-pentanedioic acid, 2-dodecyl-hexanedioic acid, 2-pentadecyl-hexanedioic acid, 2-octadecyl-hexanedioic acid, 2-eicosyl-hexane. Diacid, 2-docosyl-hexanedioic acid and the like. As the aliphatic carboxylic acid compound, a tribasic acid such as citric acid acylated with a long-chain fatty acid is also preferably used. Specific examples include the following.

[0031]

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(C) Phenol compound A compound represented by the following general formula (9) is preferably used.

[0033]

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(However, Y is -S-, -O-, -CON
_{H -, - NHSO 2 -,} CH = CHCONH -, - NH
R represents CO-, NHCONH- or -COO-
₁₃ represents an aliphatic group having 12 or more carbon atoms, and n is an integer of 1, 2 or 3. ) Specific examples of the phenol compound represented by the general formula (9) include the followings. p-
(Dodecylthio) phenol, p- (tetradecylthio) phenol, p- (hexadecylthio) phenol, p- (octadecylthio) phenol, p- (eicosylthio) phenol, p- (docosylthio) phenol, p- (tetracosylthio) phenol 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, hexagallate Decyl ester,
Octadecyl gallate, eicosyl gallate, docosyl gallate, tetracosyl gallate, N-dodecyl-p-hydroxycinnamamide, N-tetradecyl-p-hydroxycinnamamide, N-octadecyl-p -Hydroxycinnamamide, N-docosyl-p-hydroxycinnamamide, N
-Dodecyl-p-hydroxycinnamamide, N-octacosyl-p-hydroxycinnamamide, 4'-hydroxytridecaneanilide, 4'-hydroxyheptadecaneanilide, 4'-hydroxynonadecaneanilide,
3'-hydroxynonadecane anilide, 4- (N-docosylsulfonylamino) phenol, 4- (N-octadecylsulfonylamino) phenol, N- (4-hydroxyphenyl) -N'-dodecylurea, N- (4 −
Hydroxyphenyl) -N'-octadecylurea, N
-(4-hydroxyphenyl) -N'-docosylurea and the like. As the phenol compound, caffeic acid alkyl esters represented by the following general formula (10) can also be used.

[0035]

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(However, R ₁₄ is an alkyl group having 5 to 8 carbon atoms.) Specific examples of the caffeic acid alkyl ester represented by the general formula (10) include caffeic acid-n-pentyl and caffeic acid- Examples thereof include n-hexyl and caffeic acid-n-octyl. (D) Metal salt of mercaptoacetic acid A metal salt of an alkyl or alkenyl mercaptoacetic acid represented by the general formula (11) can be preferably used. _{(R 15 -S-CH 2 -COO} ) 2 M (11) ( provided that, R ₁₅ represents an aliphatic group having from 10 to 18 carbon atoms, M represents tin, magnesium, zinc or copper.) General formula ( Specific examples of the mercaptoacetic acid metal salt represented by 11) include the following.

Decylmercaptoacetic acid tin salt, dodecylmercaptoacetic acid tin salt, tetradecylmercaptoacetic acid tin salt, hexadecylmercaptoacetic acid tin salt, octadecylmercaptoacetic acid tin salt, decylmercaptoacetic acid magnesium salt, dodecylmercaptoacetic acid magnesium salt, tetradecylmercapto Magnesium acetate salt, hexadecyl mercapto acetate magnesium salt, octadecyl mercapto acetate magnesium salt, decyl mercapto acetate zinc salt,
Dodecyl mercapto acetate zinc salt, tetradecyl mercapto acetate zinc salt, hexadecyl mercapto acetate zinc salt, octadecyl mercapto acetate zinc salt, decyl mercapto acetate copper salt, dodecyl mercapto acetate copper salt, tetradecyl mercapto acetate copper salt, hexadecyl mercapto acetate copper salt,
Octadecyl mercapto acetate copper salt and the like. In the present invention, the developer is not limited to the compounds described above, and various other compounds having an electron accepting property can be used.

In the heat-sensitive recording medium of the present invention, the developer is 1 to 20 parts, preferably 2 to 10 parts, per 1 part of the color former. The color developer can be applied alone or as a mixture of two or more types, and the color former can also be applied alone or as a mixture of two or more types. As the binder resin used in the heat-sensitive recording layer, one kind or two or more kinds of various known resins can be used, and examples thereof include polyacrylamide, maleic acid copolymer, polyacrylic acid ester, polymethacrylic acid ester, vinyl chloride / Vinyl acetate copolymer,
Examples thereof include styrene copolymer, polyester, polyurethane, polyvinyl butyral, ethyl cellulose, polyvinyl acetal, polyvinyl acetoacetal, polycarbonate, epoxy resin, polyamide and the like.

In the heat-sensitive recording layer, a color former and a developer are uniformly dispersed or dissolved in an organic solvent together with a binder resin,
This is applied to a transparent support and dried to produce a coating, but the coating method is not particularly limited. When the recording layer coating liquid is a dispersion liquid in which a color developer is dispersed, the particle size of the color developer is the surface roughness of the protective layer,
As a result, it greatly affects dot reproducibility during printing.
The particle size is preferably 0.5 μm or less. The film thickness of the recording layer depends on the composition of the recording layer and the use of the thermal recording medium, but is 1 to 50 μm.
Degree, preferably about 3 to 20 μm. If necessary, various additives used in ordinary thermosensitive recording paper can be added to the coating liquid for the recording layer for the purpose of improving coatability or recording characteristics. The transparent support used in the present invention is not particularly limited, and polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate, polypropylene, polyolefin films such as polyethylene, polystyrene films or these are laminated together. A transparent film or the like, general paper, synthetic paper or the like can be used.

In the recording medium of the present invention, the protective layer prevents deformation and discoloration of the surface due to heat and pressure when heat is applied, and is therefore extremely useful for many uses. In addition to the protective layer,
It also has the role of improving chemical resistance, water resistance, abrasion resistance, and head matching. Therefore, it is preferable that the material for forming the protective layer has high strength in addition to heat resistance.
Silicone resin, polysiloxane graft polymer, UV curable resin, electron beam curable resin and the like are used. In addition,
In the present invention, a layer containing a pigment, a binder, a heat-fusible substance or the like can be provided as an intermediate layer between the support and the thermosensitive color-developing layer as required for improving smoothness.

As such a resin, in addition to a water-soluble resin,
Aqueous emulsion, hydrophobic resin and UV curable resin,
Further included are electron beam curable resins. Specific examples of the water-soluble resin include, for example, polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methyl cellulose, methoxy cellulose, hydroxy cellulose, etc.),
Casein, gelatin, polyvinylpyrrolidone, styrene-maleic anhydride copolymer, diisobutylene-maleic anhydride copolymer, polyacrylamide, modified polyacrylamide, methyl vinyl ether-maleic anhydride copolymer, carboxy-modified polyethylene, polyvinyl alcohol / Examples thereof include acrylamide block copolymer, melamine-formaldehyde resin, urea-formaldehyde resin and the like. Examples of the resin or hydrophobic resin for the aqueous emulsion include polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene /
Examples thereof include acrylic copolymers, polyacrylic acid, polyacrylic acid esters, vinyl chloride / vinyl acetate copolymers, polybutyl methacrylate, polyvinyl butyral, polyvinyl acetals, ethyl cellulose, ethylene / vinyl acetate copolymers and the like. Also, copolymers of these resins and silicon segments are preferably used. These may be used alone or as a mixture, and if necessary, a curing agent may be added to cure the resin. The type of the ultraviolet curable resin is not particularly limited as long as it is a monomer, an oligomer or a prepolymer that undergoes a polymerization reaction upon irradiation with ultraviolet rays to be cured and becomes a resin, and various known ones can be used. Although the type of the electron beam-curable resin is not particularly limited, particularly preferred electron beam-curable resins are an electron beam-curable resin having a branched molecular structure of five or more functional groups having a polyester skeleton and a silicon-modified electron beam-curable resin. It is a component.

Inorganic and organic fillers and lubricants can be added to the protective layer in order to improve the head matching within a range not deteriorating the surface smoothness. The particle size of the filler in the present invention is preferably 0.3 μm or less. In this case, as the pigment, an oil supply amount of 30 ml / 100 or more, preferably 80 ml / 100 g or more is selected. As these inorganic and / or organic pigments, one or two or more pigments commonly used for this type of thermal recording medium can be selected. Specific examples thereof include calcium carbonate,
Silica, zinc oxide, titanium oxide, aluminum hydroxide,
In addition to inorganic pigments such as zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium and silica, organic pigments such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be mentioned. The coating method of the protective layer is not particularly limited, and the coating can be performed by a conventionally known method. Preferred protective layer thickness is 0.1 to 20
μm, more preferably 0.5 to 10 μm. If the thickness of the protective layer is too thin, the storage layer of the recording medium and the function as a protective layer such as head matching are insufficient, and if it is too thick, the thermal sensitivity of the recording medium decreases and the cost is disadvantageous.

When the heat-sensitive recording medium is obtained according to the present invention, the leuco dye and the developer may be added, if necessary, to the additives commonly used in this type of heat-sensitive recording medium, such as fillers, surfactants, lubricants and pressures. An anti-coloring agent and the like can be used in combination so long as the transparency of the recording medium is not impaired. In this case, as the filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, inorganic fine powder such as surface-treated calcium or silica, and urea. -Formalin resins, styrene / methacrylic acid copolymers, polystyrene resins, vinylidene chloride resins, and other organic fine powders can be mentioned. As the lubricant, higher fatty acid and its metal salt, higher fatty acid amide, higher fatty acid ester, Various waxes of animal, vegetable, mineral or petroleum type may be mentioned. The recording method of the transparent thermosensitive recording medium of the present invention is not particularly limited, such as a hot pen, a thermal head, and laser heating, depending on the purpose of use.

Various methods are applied to the cleaning method of the present invention. Generally, either a wet method or a dry method can be adopted. Dry cleaning is performed using, for example, one or more of a cleaning roller, a cleaning brush, a cleaning belt, and a cleaning block. The cleaning roller, the cleaning brush, the cleaning belt, and the cleaning block can be formed of one or more of fiber cloth, non-woven cloth, adhesive, and abrasive. Examples of wet cleaning include cleaning by immersion in a liquid bath as shown in FIG. 2 or 3, water jet,
Cleaning with a cleaning roller, a cleaning brush, a cleaning belt, or a cleaning block as shown in FIG. In these cases, a cleaning roller, a cleaning brush, a cleaning belt or a cleaning block, a fiber cloth, a non-woven fabric, a roll on which a belt made of a water-absorbing material is wound or a roll, a block, which moistens droplets or itself. Is partly or wholly in the liquid bath, and the liquid is supplied to the liquid cleaning part at any time. The liquid used for the wet cleaning is not limited, but may be, for example, water or a volatile solvent, and especially when a surfactant and / or organic or inorganic fine particles are added to the liquid used for this cleaning The effect is improved. In the wet cleaning, a means for removing the droplets used in the cleaning can be provided after the cleaning, and for example, the droplets can be removed by thermal drying, followed by wiping and / or blowing air.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to Examples. In the following, all parts and percentages are based on weight. Example 1 The following composition was ground and dispersed by a ball mill to a particle size of 0.3 μm to prepare a recording layer coating liquid. 3-dibutylamino-7-o-chloroanilinofluorane 10 parts Octadecylphosphonic acid 30 parts Vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide Co.) 30 parts 3,4-dihydro-2-H-pyran 270 The coating solution prepared as described above was applied onto a polyester film having a thickness of 100 μm and then dried to give a thickness of 6 μm.
After the heat-sensitive recording layer of No. 1 was formed, it was stored at 70 ° C. for 10 minutes to be erased.

Next, the following composition was applied onto this recording layer, dried and irradiated with an 80 W / cm ultraviolet lamp to cure the composition, thereby forming a protective layer having a thickness of 3 μm. 75% butyl acetate solution of urethane acrylate UV curable resin (Dainippon Ink and Chemicals, Unidick C7-157) 100 parts Ethyl acetate 50 parts 52% xylene / isobutanol solution of polyether modified dimethyl polysiloxane (BYK-Chemie) Manufactured by BYK-344) 4 parts The reversible thermosensitive recording material obtained as described above is printed with a thermal printing device manufactured by Okura Electric Co., Ltd. at a printing energy of 16 mJ / mm ^2.
Printed under the following conditions. Cutting oil (cotton seed oil) on this sheet,
Lubricating oil (glycerin: 63.4 dyn / cm), rolling oil (rapeseed oil: 31.7 dyn / cm), and rust preventive oil (oleic acid) are each dropped on the surface for a few drops and stored at room temperature for one day. , Made an oil stain sample.

A sheet of this reversible thermosensitive recording material was placed at 70 ° C.
It was placed in the water tank shown in FIG. 2 at a constant water temperature. At this time, methylamyl alcohol was added to the liquid bath at a ratio of 20 to 80, and sodium alkyl sulfate as a surfactant was about 2%, and spherical iron powder as fine particles (about 50 μm diameter).
After adding 100 g to 1 liter of liquid bath, a lab stirrer (LR-51 type series manufactured by Yamato Scientific Co., Ltd.) was placed in the water tank, and the liquid bath was stirred. By putting the sheet (oil stain sample) in this warm bath, the printed image is erased, and after cleaning the sheet surface in the water tank, it is taken out from the water tank and passed in front of the air nozzle arranged on a straight line, After the water droplets were blown off by air with a pressure of 5.0 kgf / cm ^2, the degree of cleaning of the surface of the reversible thermosensitive recording material after the erasing of the print and the degree of occurrence of print unevenness during the printing again,
The durability was evaluated. This sample had a good cleaning degree and did not cause uneven printing even after repeated printing.
The durability was also good.

Example 2 As shown in FIG. 4, a unidirectionally rotatable ceramic pipe was provided with a far-infrared heater in the middle of the reversible thermosensitive recording material film belt or at the entrance / exit of the card, and the outer circumference was provided. Is equipped with a cleaning roller to which a non-woven fabric is attached, and the cleaning roller, which is kept constant at 70 ° C by a heater, is supplied with water drawn by a metering pump from a spray nozzle arranged in a straight line over the roller, and wipes it off in a wet condition at all times. I was able to work. After forming and erasing an image on the heat-sensitive recording material in this state, the same evaluation as in Example 1 was carried out. As a result, this sample was found to be well cleaned and free from uneven printing. Moreover, the durability was good.

Example 3 The same evaluation as in Example 1 was performed on the sample of Example 1 by using a method of removing droplets with a rubber blade instead of the air nozzle. As a result, the cleaning property was good, the printing was not uneven, and the durability was excellent. Comparative Example 1 The reversible thermosensitive recording material prepared and printed as in Example 1 was passed through a heat roller (hot laminator) at 70 ° C. to erase the printed image. After that, the evaluation was performed in the same manner as in Example 1. As a result, this sample had a low degree of cleaning, had many printing irregularities, and was inferior in durability.

Example 4 The same reversible thermosensitive recording medium as in Example 1 was used to prepare a sample of oil stain, which was then erased with a roller heated to 70 ° C., followed by Example 1 and The sheet surface was washed by putting it in the same water tank (however, the cleaning liquid was at room temperature). As a result, almost the same evaluation as in Example 1 was obtained.

[0051]

As described above, according to the present invention, since the surface of the reversible thermosensitive recording material is maintained in a good state by the cleaning which is carried out at the same time as the erasing of the record, good recording can be repeated. .

[Brief description of drawings]

FIG. 1 is a diagram for explaining the characteristics of a reversible thermosensitive recording material used in the method of the present invention,

FIG. 2 is a schematic view of an example of an apparatus used for carrying out the method of the present invention,

FIG. 3 is a schematic view of an example of another device used for carrying out the method of the present invention;

FIG. 4 is a schematic view of an example of still another apparatus used for carrying out the method of the present invention.

[Explanation of symbols]

 4 Liquid Bath (Cleaning Liquid) 5 Heat Pump 6 Air Blow 7 Reversible Thermosensitive Recording Material 8 Thermal Head for Printing 9 Droplet Removal Roller 10 Heat Roll for Cleaning and Erasing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoji Tsutsui 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Company (72) Inventor Masaru Shimada 1-3-3 Nakamagome, Ota-ku, Tokyo Shares In Ricoh Company (72) Inventor Taketo Yamaguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh (72) Inventor Fumito Masuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Share Ricoh Company

Claims (6)

[Claims] 1. A method for cleaning the surface of a reversible thermosensitive recording medium comprising a recording layer containing an electron-donating color-forming compound and an electron-accepting compound, wherein the cleaning means has a temperature at which the recorded information is erased. A method for cleaning a reversible thermosensitive recording medium, wherein the reversible thermosensitive recording medium is heated at the same temperature, and the reversible thermosensitive recording medium is cleaned almost simultaneously with erasing information by the cleaning means. 2. The method for cleaning a reversible thermosensitive recording medium according to claim 1, wherein the cleaning method is wet or dry. 3. The dry cleaning is a cleaning roller,
The cleaning method for reversible thermosensitive recording according to claim 2, which is carried out by a cleaning brush, a cleaning belt or a cleaning block. 4. The cleaning roller, the cleaning brush, the cleaning belt or the cleaning block used for the dry cleaning is formed of one or more of a fiber cloth, a non-woven cloth, an adhesive and an abrasive. Cleaning method for reversible thermosensitive recording medium. 5. The method for cleaning a reversible thermosensitive recording medium according to claim 3, wherein the wet cleaning is cleaning by immersion in a liquid bath or cleaning with a water jet, a cleaning roller, a cleaning brush, a cleaning belt or a cleaning block. 6. A cleaning roller, a cleaning brush, a cleaning belt or a cleaning block in the wet cleaning, which is a fiber cloth, a non-woven cloth, a roll on which a belt made of a water absorbing material is wound or a roll, a block, 6. The method for cleaning a reversible thermosensitive recording medium according to claim 5, wherein the reversible thermosensitive recording medium is moistened, or a part or all of itself is in a liquid bath, and the liquid is supplied to the liquid cleaning portion as needed.