JPH08175012A - Reversible thermal recording material - Google Patents

Abstract

PURPOSE: To provide a reversible thermal recording material reduced in the lowering of the optical density of an image part even when the development/ erasure of a color is repeated many times and capable of forming a stable image free from the yellowing in an erased color part. CONSTITUTION: In a reversible thermal recording material wherein a reversible thermal recording layer containing a usually colorless or light-colored electron donating dye precursor and a reversible coupler allowing the dye precursor to develop a color by heating and erasing the developed color by reheating is provided on a support, a protective layer composed of an ultraviolet curable or electron beam curable resin containing 3-30wt.% of hydrophobic silica particles with a mean particle size of 1-10μm is provided on the thermal recording layer or at least one intermediate layer.

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 material capable of forming and erasing an image, which can form a stable image even if it is colored / erased a large number of times by heating.

[0002]

2. Description of the Related Art In general, a particle-sensitive thermal recording material comprises a support and a thermal recording layer containing an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting developer as main components. By heating with a thermal head, a heating pen, a laser beam, etc., a dye precursor and a developer react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45
-14039 gazette etc. are disclosed.

In general, such a heat-sensitive recording material cannot erase the portion of the image once formed and return to the state before the image is formed. Therefore, when further information is recorded, the image is not recorded. There was no choice but to add to the formation part. Therefore, when the area of the heat-sensitive recording portion is limited, there is a problem that the recordable information is limited and it is impossible to record all the necessary information.

In recent years, reversible thermosensitive recording materials capable of repeating image formation and image erasing have been devised in order to deal with such a problem, for example, JP-A-54-119377 and JP-A-63-63. 39377, JP-A-63-4
Japanese Patent No. 1186 describes a heat-sensitive recording material composed of a resin base material and organic low-molecules dispersed in the resin base material. However, since this method reversibly changes the transparency of the heat-sensitive recording material by heat energy, the contrast between the image-formed area and the image-unformed area is insufficient.

Further, in the methods described in JP-A-50-81157 and JP-A-50-105555, since the image to be formed changes according to the ambient temperature, the image forming state and the erasing state. The holding temperatures are different, and these two states cannot be held for an arbitrary period at room temperature.

Further, in Japanese Patent Laid-Open No. 59-120492, the hysteresis characteristic of the color-developing component is utilized to keep the recording material in the hysteresis temperature range, thereby forming an image.
Although a method of maintaining the erased state is described, this method requires a heating source and a cooling source for image formation and erasure, and the temperature range in which the image formation state and the erased state can be maintained is limited to the hysteresis temperature region. However, it is still insufficient for use in the temperature environment of daily life.

On the other hand, JP-A-2-188293, JP-A-2-188294, and International Publication No. WO90 /
No. 11898 describes a reversible thermosensitive recording medium composed of a leuco dye and a color-developing and decoloring agent for coloring and decoloring the leuco dye by heating. The color-developing agent is an amphoteric compound having an acidic group for coloring the leuco dye and a basic group for decoloring the colored leuco dye, and the coloring effect by the acidic group or the decoloring effect by the basic group is controlled by controlling thermal energy. One of them is preferentially generated, and coloring and erasing are performed. However, in this method, it is impossible to completely switch the color development reaction and the color removal reaction only by controlling the thermal energy, and since both reactions occur at a certain ratio at the same time, sufficient color development density cannot be obtained, and the color removal Can not be done completely. Therefore, sufficient image contrast cannot be obtained.

Further, since the decoloring action of the basic group also acts on the color-developed portion at room temperature, the phenomenon that the density of the color-developed portion decreases with time cannot be avoided. Further, JP-A-5-124360 describes a reversible thermosensitive recording medium that develops and decolorizes a leuco dye by heating, and an organic phosphoric acid compound, an α-hydroxyaliphatic carboxylic acid as an electron-accepting compound, Specific phenol compounds such as alkylthiophenol, alkyloxyphenol, alkylcarbamoylphenol, and gallic acid alkylester having a fatty acid dicarboxylic acid and an aliphatic group having 12 or more carbon atoms are exemplified. However, even this recording medium cannot simultaneously solve the two problems of low color density or incomplete decoloring.

On the other hand, formation of an image with good contrast
We have found a novel reversible developer capable of being erased and capable of retaining a stable image over time in the environment of everyday life, and it was previously proposed in Japanese Patent Application No. 347032/1992. . However, although the reversible thermosensitive recording material obtained by this method was capable of forming and erasing an image with good contrast, there was a drawback that the erasing part turned yellow when the coloring / erasing was repeated many times. It was

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reversible heat-sensitive material capable of forming an image and erasing an image by heating, stably performing color development / erasing a large number of times, and causing no yellowing of an erased portion. It is to provide a recording material.

[0011]

Means for Solving the Problems As a result of research to solve this problem, the present inventors have found that two or more layers provided directly on the reversible thermosensitive recording layer or directly on the reversible thermosensitive recording layer. By constructing a protective layer made of an ultraviolet curable or electron beam curable resin containing particles of hydrophobic silica directly on the intermediate layer, a stable image can be formed even when coloring / erasing a large number of times, and an erasing part can be formed. It was possible to prepare a reversible heat-sensitive recording material which did not yellow.

[0012] Hydrophobic silica refers to the hydroxyl group contained in the porous synthetic silica as an organosilicon compound such as silanes,
It is completely hydrophobized by chemically reacting with silazanes, polysiloxanes, etc., and has a di-n-butylamine value of 100 meq / kg or less. The method for producing the porous synthetic silica and the organosilicon compound includes those performed in an organic solvent, a pressure method, a catalyst heating method and the like, which are already known.

[0013] Hydrophobic silica is completely hydrophobic because it has few hydroxyl groups on the particle surface. On the other hand, adhesion with an organic solvent or a solvent-based binder is superior to that of a particle-untreated porous synthetic silica. . Therefore, it has better compatibility and dispersibility with ultraviolet curable or electron beam curable resins than ordinary porous synthetic silica.

The reversible thermosensitive recording material may be exposed to extremely harsh conditions when color is developed, and for example, the reversible thermosensitive recording material may be exposed to very severe conditions in a short time.
Hydrophobic silica even under the condition that a set of minute heating elements that generate heat above 00 ° C. is pressed with a strong pressure to cause color development, and at the same time that the reversible thermosensitive recording material and the group of minute heating elements are developed while sliding. As a result, the contact area with the minute heating element becomes smaller, making it more difficult for the protective layer to break,
In addition, the hydrophobized silica itself does not break or melt due to its heat or pressure, and these effects are maintained even when the color is developed many times. Thus, it is possible to form a stable image even if the coloring / erasing is performed a large number of times, and further, due to the good dispersibility of the hydrophobic silica, it is possible to disperse it uniformly in the protective layer made of an ultraviolet curable or electron beam curable resin. In addition, the heat resistance of the protective layer is improved, and yellowing of the decolored portion due to many times of coloring / erasing is not seen. The effect will be demonstrated in the following example.

The particles of the hydrophobic silica in the protective layer used in the present invention have an average particle size of 1 to 10 μm, preferably 1 to 10 μm.
The particle size is 5 μm, and the compounding amount is 3 to 30% by weight, preferably 5 to 20% by weight. A method in which this is kneaded with an electron beam curable resin or an ultraviolet ray curable resin in a mortar, a three-roll mill, or the like, and particles of hydrophobic silica are dispersed in a solvent, and further dispersed in the electron beam curable resin or the ultraviolet ray curable resin. For example, hydrophobic silica particles are included.

Further, in order to prevent or reduce sticking after the electron beam curable resin or the ultraviolet ray curable resin is cured, a pigment may be contained in the electron beam curable resin composition together with the hydrophobic silica particles. .
The pigment here may be either an organic pigment or an inorganic pigment. For example, diatomaceous earth, clay, calcined clay, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, aluminum hydroxide, starch granules, urea-formalin resin, synthetic resin particles such as melamine resin and the like. However, the present invention is not limited to these. These pigments can be used alone or in combination of two or more kinds.

Furthermore, for the purpose of preventing sticking and head wear, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearic acid amide and castor wax are used. Further, one kind or two or more kinds of a leveling agent, a dispersant, a surfactant, a fluorescent dye and the like can be contained.

The usually colorless to light-colored electron-donating dye precursor used in the present invention is represented by those generally used for pressure-sensitive recording paper, heat-sensitive recording paper, etc., but is not particularly limited. Specific examples include the followings, but the present invention is not limited thereto.

(1) Triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-)
Yl) -6-Dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5 -Dimethylaminophthalide, 3-p
-Dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like,

(2) Diphenylmethane compound 4,4'-bis (dimethylaminophenyl) benzhydryl benzyl ether, N-chlorophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, etc.

(3) Xanthene compound Rhodamine B anilinolactam, Rhodamine B p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3- Diethylamino-7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3 -Diethylamino-7
-(2-chloroanilino) fluorane,

3-Diethylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl) tolylamino-
6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl) tolylamino-6-methyl-7-phenethylfluorane, 3-diethylamino-7 -(4-Nitroanilino) fluorane, 3-dibutylamino-6-methyl-7
-Anilinofluorane, 3- (N-methyl) propylamino-6-methyl-7-anilinofluorane, 3- (N
-Ethyl) isoamylamino-6-methyl-7-anilinofluorane, 3- (N-methyl) cyclohexylamino-6-methyl-7-anilinofluorane, 3- (N-
Ethyl) tetrahydrofurylamino-6-methyl-7-
Anilino Fluoran, etc.

(4) Thiazine-based compounds benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.

(5) Spiro compound 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3 -Methoxybenzo) spiropyran, 3-propylspirobenzopyran and the like.

The usually colorless to light-colored dye precursors may be used either individually or in combination of two or more.

The reversible color developer used in the present invention will be described below, but the invention is not limited thereto.

The reversible color developer used in the present invention is not particularly limited as long as it is a compound capable of reversibly changing the color tone of the dye precursor by heating, but from the viewpoint of image contrast, durability of repetition, etc. 6-210954
An electron-accepting compound represented by the following chemical formula 1 is preferably used, including a reversible color developer composed of a phenolic compound proposed in Japanese Patent Laid-Open Publication No. 2003-242242.

[0028]

Embedded image In Formula 1, n represents 1, 2 or 3. m is 0, 1 or 2
Represents Q represents an aliphatic hydrocarbon group, an alkoxy group or a halogen atom. The ring represented by A is an aromatic ring. X is a divalent group bonded to the aromatic ring represented by A via a nitrogen atom, a divalent group containing two or more heteroatoms, a nitrogen atom-containing aromatic ring represented by A and a carbon number of 1 It represents a divalent group bonded by the above hydrocarbon group or a divalent group containing an unsaturated bond or an aromatic ring. R represents an aliphatic hydrocarbon group. Of the atoms contained in X and R, the total number of atoms excluding hydrogen atoms and the atoms constituting the aromatic ring is 8 or more.

Specific examples of the substituent represented by Q include methyl group, ethyl group, propyl group, isopropyl group and n-
Butyl group, t-butyl group, t-pentyl group, 2-ethylhexyl group, cyclohexyl group, allyl group and other aliphatic hydrocarbon groups, methoxy group, ethoxy group, n-propyloxy group, i-propyloxy group, n -Butyloxy group, n
-Alkoxy groups such as an octyloxy group and halogen atoms such as fluorine, chlorine, bromine and iodine.

Examples of the divalent group in which X is bonded to the aromatic ring represented by A through the nitrogen atom include -NHCO- and-.
NH-, -NHCONH-, -NHCONHNH-,-
N = CH -, - N = N -, - NHSO 2 -, - NHCO
_{(P-C 6 H 4)} NHCO -, - NHCO (p-C 6 H 4)
NHCONH -, - NHCO (p- C 6 H 4) NHCOC
ONH -, - NHCO (p- C 6 H 4) CONH -, - N
_{HCO (p-C 6 H 4} ) CONHNHCO -, - NHCO
_{(P-C 6 H 4)} OCONH -, - NHCO (p-C
₆ H ₄ ) NHCOO-, -NHCOCH ₂ (m-C ₆ H ₄ ).
_{NHCO-, -NHCOCH 2 (p-C} 6 H 4) NHCO
_{-, - NHCOCH 2 (p-} C 6 H 4) NHCONH-,
_{-NHCOCH 2 (p-C 6 H} 4) NHCOCONH-,
_{-NHCOCH 2 (p-C 6 H} 4) CONH -, - NHC
_{OCH 2 (p-C 6 H} 4) CONHNHCO -, - NHC
_{OCH 2 (p-C 6 H} 4) CONHNHCONH -, - N
_{HCOCH 2 (p-C 6 H} 4) CONHNHCOO-, -
_{NHCOCH 2 (p-C 6 H} 4) OCONH -, - NHC
_{OCH 2 (p-C 6 H} 4) NHCOO-, -NHCOCH
_{2 CH 2 (p-C 6} H 4) NHCO -, - NHCOCH 2 C
_{H 2 (p-C 6 H} 4) NHCONH -, - NHCOCH 2 C
_{H 2 (m-C 6 H} 4) NHCOO -, - NHCOCH 2 CH
_{2 (p-C 6 H 4} ) NHCOCONH -, - NHCOCH 2
_{CH 2 (p-C 6 H} 4) CONH -, - NHCOCH 2 CH
_{2 (p-C 6 H 4} ) CONHNHCO -, - NHCOCH 2
_{CH 2 (p-C 6 H} 4) CONHNHCONH- the like. When a hydrogen atom is bonded to the nitrogen atom, the hydrogen atom may be substituted with an aliphatic hydrocarbon group such as a methyl group or a cyclohexyl group. Of these, the urea bond is more preferable in terms of decoloring property and image density. Interestingly when X is -CONH-, -COO-, -S-,
Either the decoloring property or the image density is unsatisfactory.

Examples of the divalent group where X is two or more hetero atoms include --SO ₂ NH--, --SS--, --CON.
_{HNH -, - CONHNHCO-, -CONHCH 2} C
O -, - CONHNHCOO -, - CONHCH 2 CO
_{O-, -CONHNHCONH -, - CONHCH 2} C
ONH-, -CONHNHCONHNH-, -CON
_{HCH 2 CONHNH -, - CH 2} NHCONH -, - C
_{H 2 CH 2 NHCONH -, -} CH 2 CH 2 CH 2 NHCO
_{NH -, - CH 2 CH 2} CH 2 NHCONH -, - SCH 2
_{CONH -, - SCH 2 CH 2} CONH -, - S (C
_{H 2) 5 CONH-, -S (} CH 2) 10 CONH -, - S
_{(P-C 6 H 4)} CONH -, - SCH 2 NHCO -, -
_{SCH 2 CH 2 NHCO -, -} S (CH 2) 6 NHCO-,
_{-S (p-C 6 H 4} ) NHCO -, - SCH 2 NHCON
_{H -, - SCH 2 CH 2} NHCONH-, -S (CH 2)
_{6 NHCONH -, - S (p} -C 6 H 4) NHCONH
_{-, - S (CH 2)} 10 NHCONH -, - SCH 2 CH 2
_{NHCOO-, -S (CH 2) 6} NHCOO -, - S
_{(P-C 6 H 4)} NHCOO -, - S (CH 2) 6 OCON
H -, - S (p- C 6 H 4) OCONH -, - S (C
_{H 2) 11 OCONH-, -SCH 2} CH 2 CONH -, -
_{S (CH 2) 5 CONH -} , - SCH 2 CH 2 NHCO (p
_{-C 6 H 4) -, -} SCH 2 CONHNHCO -, - SC
_{H 2 CH 2 CONHNHCO -, -} S (CH 2) 6 CONH
_{NHCO-, -S (CH 2) 6} CONHNHCO (p-
_{C 6 H 4) -, -} S (CH 2) 10 CONHNHCO-, -
_{S (p-C 6 H 4} ) CONHNHCO -, - SCH 2 (p
_{-C 6 H 4) CONHNHCO-, -SCH} 2 CH 2 NH
_{COCONH -, - SCH 2 CH 2} CH 2 NHCOCON
_{H -, - S (CH 2} ) 11 NHCOCONH -, - S (p
_{-C 6 H 4) NHCOCONH-, -SCH} 2 CONHC
_{ONH -, - SCH 2 CH 2} CONHCONH -, - S
_{(P-C 6 H 4)} CONHCONH -, - SCH 2 CH 2 N
HCONHCO -, - S (p- C 6 H 4) NHCONHC
_{O -, - SCH 2 CH 2} CONHNHCONH-, -S
_{(CH 2) 10 CONHNHCONH -,} - SCH 2 CH 2
NHNHCONH -, - S (p- C 6 H 4) NHNHCO
_{NH -, - SCH 2 CH 2} NHCONHNH -, - S (p
_{-C 6 H 4) NHCONHNH -,} - SCH 2 CONHC
ONHNH-, -SCH ₂ CH ₂ CONHCONHNH
_{-, - S (CH 2)} 10 CONHCONHNH-, -S
_{(P-C 6 H 4)} CONHNHCONH -, - S (p-C
₆ H ₄ ) CONHCONHNH-, -SCH ₂ CONHC
_{ONHNHCO -, - SCH 2 CH 2} CONHCONHN
_{HCO -, - S (CH 2} ) 10 CONHCONHNHCO
_{-, -S (p-C 6} H 4) CONHNHCONHCO
-, - S (p-C 6 H 4) CONHCONHNHCO-,
_{-SCH 2 CONH (CH 2) NHCO} -, - SCH 2 C
_{H 2 CONH (CH 2) NHCO} -, - S (p-C 6 H 4)
_{CONH (CH 2) NHCO -,} - S (CH 2) 10 CON
_{H (CH 2) NHCO -,} - SCH 2 CON (CH 2) N
_{HCONH -, - SCH 2 CH 2} CON (CH 2) NHC
_{ONH -, - S (CH 2} ) 10 CONHCONH (CH 2)
NHCO -, - S (p- C 6 H 4) CONH (CH 2) N
_{HCO -, - SCH 2 CH 2} NHCONH (CH 2) NH
_{CO -, - SCH 2 CH 2} NHCOCH 2 CONH -, -
_{S (p-C 6 H 4} ) NHCONH (CH 2) NHCO-,
_{-S (p-C 6 H 4} ) NHCOCH 2 CONH- , and the like. Specific examples of the hetero atom include oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, boron atom, silicon atom, selenium atom, fluorine atom, chlorine atom, bromine atom, iodine atom,
Examples include tin atoms.

2 wherein X contains an unsaturated bond or an aromatic ring
Examples of the valent group include -CH = CH-, -CH = N-,
—SO ₂ —, a phenylene group, a group containing a carbon-carbon triple bond, a group in which they are combined, and further, on one or both sides thereof, —NHCO mentioned above as another example of X.
-, -NH-, -NHCONH-, -NHCSNH-,
-N = CH -, - N = N -, - NHSO 2 -, - SO 2 N
Examples thereof include groups combining one or two or more linking groups such as H and -SS-. In this case, in addition to the linking group, -CONH-, -O-, -S-, -COO-, -O.
CO -, - OCOO, -CO - , - SO 2 - 2 a divalent group, such as may also be mentioned.

Examples of the divalent group in which X contains a nitrogen atom and is bonded to the aromatic ring represented by A by a hydrocarbon group having 1 or more carbon atoms are --CH ₂ CONH--, --CH ₂ CH ₂ CO
_{NH -, - CH 2 NHCO -} , - CH 2 CH 2 NHCO
_{-, - CH 2 CH 2 CH} 2 NHCO -, - CH 2 CH 2 NH
_{COO -, - (CH 2)} 6 NHCOO -, - (p-C
_{6 H 4) NHCOO -, -} CH 2 CH 2 OCONH-, -
_{(CH 2) 11 OCONH -,} - (p-C 6 H 4) OCON
_{H -, - CH 2 CH 2} CONHCO -, - (CH 2) 5 CO
_{NHCO -, - CH 2 CH 2} CONHCO (p-C 6 H 4)
_{-, -CH 2 CONHNHCO -, -} CH 2 CH 2 CON
_{HNHCO -, - (CH 2)} 5 CONHNHCO -, -
_{(CH 2) 5 CONHNHCO (p} -C 6 H 4) -, -
_{(CH 2) 10 CONHNHCO -,} - (p-C 6 H 4) C
_{ONHNHCO-, -CH 2 (p-C} 6 H 4) CONHN
_{HCO -, - CH 2 CH 2} NHCOCONH-, -CH 2
_{CH 2 CH 2 NHCOCONH -, -} (CH 2) 10 NHC
_{OCONH-, - (p-C 6} H 4) NHCOCONH
_{-, - CH 2 CONHCONH-, -CH} 2 CH 2 CON
HCONH -, - (p-C 6 H 4) CONHCONH-,
_{-CH 2 CH 2 NHCONHCO -, -} (p-C 6 H 4) N
_{HCONHCO -, - CH 2 CH 2} NHCONHNH-,
_{- (p-C 6 H 4} ) NHCONHNH -, - CH 2 CH 2 N
HNHCONH -, - (p-C 6 H 4) NHNHCONH
_{-, -CH 2 CONHNHCONH -, -} CH 2 CH 2 C
_{ONHNHCONH-, - (CH 2) 10} CONHNHC
ONH -, - (p-C 6 H 4) NHNHCO-, -CH 2
_{CONHCH 2 NHCO -, - CH 2} CH 2 CONHCH 2
_{NHCO -, - (CH 2)} 10 CONHCH 2 NHCO-,
_{- (p-C 6 H 4} ) CONHCH 2 NHCO-, -CH 2
CONHCH ₂ NHCONH-, -CH ₂ CH ₂ CONH
_{CH 2 NHCONH-, - (CH 2} ) 10 CONHCH 2 N
HCONH -, - (p-C 6 H 4) CONHCH 2 NHC
_{ONH -, - CH 2 CH 2} NHCONHCH 2 NHCO
_{-, - (p-C 6} H 4) NHCONHCH 2 NHCO-,
_{-CH 2 CH 2 NHCOCH 2 CONH -} , - (p-C 6 H
₄ ) NHCOCH ₂ CONH- and the like.

As the aliphatic hydrocarbon group represented by R,
Hexyl group, octyl group, nonyl group, cyclohexyl group, decyl group, undecyl group, dodecyl group, cyclododecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, 16-methylheptadecyl group, octadecyl group, 9-octadecenyl group, nonadecyl group, aicosyl group, henicosyl group,
Examples thereof include docosyl group, tricosyl group, tetracosyl group, 2-norbornyl group, 7,7-dimethylnorbornyl group, 1-adamantyl group, cholesteryl group and 5-phenylpentyl group. These may be branched, may be polycyclic, and may contain an unsaturated bond. However, it is necessary for the decoloring property that the total number of the atoms included in X and R excluding the hydrogen atom and the atoms constituting the aromatic ring is 8 or more, particularly 14 or more.

Next, specific examples of the reversible color developer preferably used in the present invention will be given, but the present invention is not limited thereto.

4'-hydroxyheptane anilide, 4 '
-Hydroxy-3-methyloctaneanilide, 4'-hydroxynonadecaneanilide, 3'-hydroxynonadecaneanilide, 4'-hydroxy-10-octadeceneanilide, 15-cyclohexyl-4'-hydroxypentadecaneanilide, 4'- Hydroxy-5-tetradeceneanilide, 3'-cyclohexyl-4'-hydroxyheptadecaneanilide, 3'-allyl-4'-hydroxypentadecaneanilide, 3'-chloro-4'-hydroxyoctadecaneanilide, 3'-hydroxydodecane Anilide, 2 ', 4'-dihydroxyheptadecane anilide,

4'-hydroxy-4-hexylbenzanilide, 4'-hydroxy-4-octadecylbenzanilide, 4'-hydroxy-4-pentadecylaminocarbonylbenzanilide, 4'-hydroxy-4-hexylcarbonylaminobenz Anilide, 4'-hydroxy-4- (heptylthio) benzanilide, 4'-hydroxy-4-octadecyloxybenzanilide, 4 '
-Hydroxy-4-dodecylsulfonylbenzanilide, 4'-hydroxy-4-nonylsulfonyloxybenzanilide, 4'-hydroxy-4-dodecyloxysulfonylbenzanilide, 4'-hydroxy-4-pentadecylaminosulfonylbenzanilide, 4'-hydroxy-4- (N-heptadecylideneamino) benzanilide,

4'-Hydroxy-3,4-dioctyloxybenzanilide, 4'-hydroxy-3-octyl-4- (octylthio) benzanilide, 4'-hydroxy-3- (heptadecylthio) -5-pentadecyloxybenz Anilide, 4'-hydroxy-3-heptadecylcarbonylamino-5-dodecylbenzanilide,
4'-hydroxy-3-octadecylaminocarbonyl-5-tetradecylaminocarbonylbenzanilide,
4'-hydroxy-3-octadecylsulfonylamino-5-octadecyloxybenzanilide, 4'-hydroxy-3-heptadecyloxysulfonyl-5-tetradecyloxysulfonylbenzanilide, 4'-hydroxy-3,5-bis ( N-docosylideneamino) benzanilide,

4'-hydroxy-4-octadecylcarbonylaminobenzanilide, 4'-hydroxy-3-
Octadecylcarbonylamino-5-octadecyloxybenzanilide, 3'-allyl-4'-hydroxy-
4-pentadecylbenzanilide, 4'-hydroxy-
3'-methyl-4-nonyloxybenzanilide, 4 '
-Hydroxy-3'-propyl-4-nonadecylcarbonyloxybenzanilide, 3'-butyl-4'-hydroxy-4-octadecyloxycarbonylbenzanilide, 3'-hydroxy-4-pentadecylcarbonyloxybenzanilide, 3 '-Hydroxy-4-nonadecylsulfonylbenzanilide, 3', 4 ', 5'-trihydroxy-4-tetracosylaminosulfonylbenzanilide, 3', 5'-dihydroxy-4-pentacosylaminocarbonylbenz Anilide, 3'-hydroxy-4- (N-dodecylideneamino) benzanilide,
N- [4- (3-hydroxyphenylaminocarbonyl) benzylidene] pentadecylamine,

N-cyclohexyl-4-hydroxybenzhydrazide, N-cyclohexylmethyl-4-hydroxybenzhydrazide, N-cyclohexyl-4-hydroxybenzamide, N-cyclohexylmethyl-4-
Hydroxybenzamide, N-methyl-N-octadecyl-4-hydroxybenzamide, N- (3-methylhexyl) -4-hydroxybenzamide, N-octadecyl-4-hydroxybenzhydrazide, N- (8-octadecenyl) -4- Hydroxybenzamide,

4-hydroxy-4'-dodecylbenzanilide, N-methyl-4-hydroxy-4'-octadecylbenzanilide, 4-hydroxy-4'-octadecyloxybenzanilide, 4-hydroxy-4'-
(Octadecylthio) benzanilide, 4-hydroxy-4'-hexadecylcarbonylbenzanilide, 4-
Hydroxy-4′-heptadecyloxycarbonyloxybenzanilide, 4-hydroxy-4′-dodecyloxycarbonylbenzanilide, 4-hydroxy-4 ′
-Heptadecyl carbonyloxybenzanilide, 4-
Hydroxy-4′-cyclohexylaminobenzanilide, 4-hydroxy-4′-octadecylaminobenzanilide,

4-Hydroxy-4'-heptadecylcarbonylaminobenzanilide, 4-hydroxy-4'-
Octadecylaminocarbonylbenzanilide, 4-hydroxy-4'-dodecylsulfonylbenzanilide, 4-hydroxy-4'-octadecyloxysulfonylbenzanilide, 4-hydroxy-4'-dodecylsulfonyloxybenzanilide, N-4-hydroxybenzoyl -N'-octadecylidene-1,4-phenylenediamine, N-4- (4-hydroxyphenylcarbonylamino) benzylidenedecylamine, 4-
Hydroxy-4′-tetradecyloxycarbonylaminobenzanilide, 4-hydroxy-4′-octadecylureylenebenzanilide,

3-Hydroxy-4'-dodecyloxybenzanilide, N-methyl-4-hydroxy-3'-octadecyloxybenzanilide, 3-hydroxy-
4'-tetradecylbenzanilide, N-methyl-3-
Hydroxy-4'-octadecylbenzanilide, N-
Dodecyl-4-hydroxy-3-methylbenzamide,
3-Methoxy-4-hydroxy-4'-octadecyloxybenzanilide, 3-chloro-4-hydroxy-
4'-octadecylbenzanilide, N-octadecyl-4-hydroxy-2,5-dimethylbenzamide, 4
-Hydroxy-4'-octadecyloxy-3'-chlorobenzanilide, 4-hydroxy-3 ', 4'-didecyloxybenzanilide, 4-hydroxy-3'-octadecylamino-4'-octadecyloxybenzanilide, 4-hydroxy-2'-chloro-3 ', 5'-
Didecyloxybenzanilide, 4-hydroxy-
3 ', 4'-dioctadecyloxybenzanilide, 4
-Hydroxy-4'-octyl-3'-methylbenzanilide, 3-hydroxy-4-methyl-4'-tetradecylbenzanilide, N-methyl-4-hydroxy-
3'-octadecylbenzanilide,

4- (N-octadecylsulfonylamino) phenol, 4- (N-methyl-N-octadecylsulfonylamino) phenol, 4- (N-3-methylhexylsulfonylamino) phenol, 4'-hydroxy-4- Cyclohexylbenzene sulfone anilide,
4'-hydroxy-4-octadecyloxybenzenesulfonanilide, 4'-hydroxy-4- (dodecylthio) benzenesulfonanilide, 4'-hydroxy-4
-Hexylcarbonylbenzenesulfonanilide, 4 '
-Hydroxy-4- (8-heptadecenyl) carbonylbenzenesulfonanilide, 4'-hydroxy-4-octyloxycarbonyloxybenzenesulfonanilide, 4'-hydroxy-4-dodecylcarbonyloxybenzenesulfonanilide, 4'-hydroxy-4 -Octadecylaminobenzenesulfonanilide,

4'-hydroxy-4-heptadecylcarbonylaminobenzenesulfonanilide, 4'-hydroxy-4-dodecylaminocarbonylbenzenesulfonanilide, 4'-hydroxy-4-dodecylsulfonylbenzenesulfonanilide, 4'-hydroxy- 4-Octadecyloxysulfonylbenzenesulfonanilide, 4'-hydroxy-4-dodecylsulfonyloxybenzenesulfonanilide, N-dodecylidene-4-
(4-hydroxyphenyl) aminosulfonylaniline, N-4- (4-hydroxyphenylaminosulfonyl) benzylidene octadecylamine, 4'-hydroxy-4-octyloxycarbonylaminobenzenesulfonanilide, 4'-hydroxy-4-octadecyloxy Carbonylaminobenzenesulfonanilide, 4 '
-Hydroxy-4-octadecylureylene benzenesulfonanilide,

N-methyl-4'-hydroxy-3-octadecyloxybenzenesulfonanilide, 3'-hydroxy-4-dodecylbenzenesulfonanilide, 3-
Methyl-4- (N-dodecylsulfonamino) phenol, 3'-methoxy-4'-hydroxy-4-octadecyloxybenzenesulfonanilide, 3'-chloro-
4'-hydroxy-4-octadecylbenzenesulfonanilide, 4'-hydroxy-2,5-dimethyl-4-
Octadecylbenzenesulfonanilide, 3-methyl-
4- (N-octadecylsulfonamino) phenol,
4'-hydroxy-3,4-dioctadecyloxybenzenesulfonanilide,

1- (4-hydroxyphenyldithio) octadecane, 1- (4-hydroxyphenyldithio)-
9-octadecene, 1- (2-fluoro-4-hydroxyphenyldithio) octadecane, 1- (2-ethoxy-4-hydroxyphenyldithio) octadecane, 1-
(3-chloro-4-hydroxyphenyldithio) octadecane,

4'-hydroxy-4-tetradecyldiphenyl sulfide, 4'-hydroxy-4-octadecyldiphenyl sulfide, 4'-hydroxy-4-octadecylcarbonylaminodiphenyl sulfide, 4 '
-Hydroxy-4-octadecyloxydiphenyl sulfide, 4'-hydroxy-4-octadecyloxysulfonyl diphenyl sulfide, 4'-hydroxy-4
-Octadecylsulfonylaminodiphenyl sulfide,

4'-hydroxy-3,4-didecyloxydiphenyl sulfide, 4'-hydroxy-3,4-
Dioctadecyloxydiphenyl sulfide, 4- (1
5-cyclohexylpentadecyl) -4'-hydroxydiphenyl sulfide, 4'-hydroxy-4- (5-
Tetradecenyl) diphenyl sulfide,

3'-chloro-4'-hydroxy-4-octadecyldiphenyl sulfide, 3'-hydroxy-
4-dodecyl diphenyl sulfide, 3'-hydroxy-4-octadecyl diphenyl sulfide, 3'-hydroxy-4-dodecyloxycarbonyl diphenyl sulfide,

N- (4-hydroxyphenyl) -N'-
Hexyl urea, N- (4-hydroxyphenyl) -N '
-Dodecyl urea, N- (4-hydroxyphenyl)-
N'-hexadecylurea, N- (4-hydroxyphenyl) -N'-octadecylurea, N- (4-hydroxyphenyl) -N'-eicosylurea, N- (4-hydroxyphenyl) -N'-cyclododecyl Urea, N- (4
-Hydroxyphenyl) -N'-docosylurea, N-
(4-hydroxyphenyl) -N'-cholesteryl urea, N- (4-hydroxyphenyl) -N '-(2-heptyloctyl) urea, N- (4-hydroxyphenyl) -N'-(9-octadecenyl) urea,

N- (3-allyl-4-hydroxyphenyl) -N'-octadecylurea, N- (2-hydroxyphenyl) -N'-octylurea, N- (3-hydroxyphenyl) -N'-octadecyl Urea, N- (3,4
-Dihydroxyphenyl) -N'-octadecylurea,
N- (3,4,5-trihydroxyphenyl) -N'-
Tricosyl urea, N- (4-hydroxyphenyl)-
N '-(4-tetradecylphenyl) urea, N- (4-
Hydroxyphenyl) -N'-hexadecylthiourea,
N- (4-hydroxyphenyl) -N'-octadecylthiourea,

4-undecanoylamino-1- (4-hydroxyphenylaminocarbonyl) benzene, 4-octadecanoylamino-1- (4-hydroxyphenylaminocarbonyl) benzene, 4- (octadecylaminocarbonyl) amino- 1- (4-hydroxyphenylaminocarbonyl) benzene, 4-octadecylamino-1- (4-hydroxyphenylamino) carbonylmethylbenzene, N-octadecyl-N'-p- (4-hydroxyphenylcarbamoyl) phenyloxamide,
4- (octadecylaminocarbonyl) amino-1-
(4-Hydroxyphenylcarbamoyl) methylbenzene, 4- (octadecylamino) carbonyl-1- (4
-Hydroxyphenylcarbamoyl) methylbenzene,
N-octadecanoyl-N'-p- (p-hydroxyphenylcarbamoylmethyl) benzoylhydrazine, N
-Dodecanoyl-N'-p- [2- (p-hydroxyphenylcarbamoyl) ethyl] benzoylhydrazine,

N- (4-hydroxyphenylmethyl)-
N'-n-tetradecyl urea, N- (4-hydroxyphenylmethyl) -N'-n-octadecyl urea, N-
[2- (4-hydroxyphenyl) ethyl] -N'-n
-Tetradecyl urea, N- [2- (4-hydroxyphenyl) ethyl] -N'-n-octadecyl urea, N-
[3- (4-hydroxyphenyl) propyl] -N'-
n-dodecyl urea, N- [3- (4-hydroxyphenyl) propyl] -N'-n-octadecyl urea, N-
[6- (4-hydroxyphenyl) hexyl] -N'-
n-dodecylurea, N- [2- (3-hydroxyphenyl) ethyl] -N'-n-octadecylurea, N- [2
-(3,4-Dihydroxyphenyl) ethyl] -N'-
n-octadecyl urea,

Nn-octadecyl- (4-hydroxyphenyl) acetamide, Nn-dodecyl-3- (4
-Hydroxyphenyl) propanamide, Nn-octadecyl-3- (4-hydroxyphenyl) propanamide, N- (4-hydroxyphenylmethyl) octadecane amide, N- [2- (4-hydroxyphenyl) ethyl] octadecane Amide, N- [3- (4-hydroxyphenyl) propyl] octadecanamide, N- [3
-(3-Hydroxyphenyl) propyl] octadecanamide, N- [3- (3,4-dihydroxyphenyl)
Propyl] octadecanamide,

N- (4-hydroxybenzoyl) -N '
-N-octanoylhydrazine, N- (4-hydroxybenzoyl) -N'-n-tetradecanoylhydrazine, N- (4-hydroxybenzoyl) -N'-n-octadecanoylhydrazine, N- (2, 4-dihydroxybenzoyl) -N'-n-octanoylhydrazine,
N- (2,4-dihydroxybenzoyl) -N'-n-
Octadecanoylhydrazine, N- (4-hydroxybenzoyl) -N'-n-tetradecylaminocarbonylhydrazine, N- (4-hydroxybenzoyl) -N '
-N-octadecylaminocarbonylhydrazine, N-
(2,4-dihydroxybenzoyl) -N'-n-tetradecylaminocarbonylhydrazine, N- (2,4-
Dihydroxybenzoyl) -N'-n-octadecylaminocarbonylhydrazine, N- (4-hydroxybenzoyl) -N'-n-octyloxycarbonylhydrazine, N- (4-hydroxybenzoyl) -N'-n-
Dodecyloxycarbonyl hydrazine, N- (2,4-
Dihydroxybenzoyl) -N'-n-tetradecyloxycarbonylhydrazine, N- (2,4-dihydroxybenzoyl) -N'-n-octadecyloxycarbonylhydrazine, N- (4-hydroxybenzoyl)-
N'-n-tetradecylhydrazinocarbonylhydrazine, N- (4-hydroxybenzoyl) -N'-n-octadecylhydrazinocarbonylhydrazine, N-
(2,4-dihydroxybenzoyl) -N'-n-tetradecylhydrazinocarbonylhydrazine, N- (2,2
4-dihydroxybenzoyl) -N'-n-octadecylhydrazinocarbonylhydrazine,

N- (4-hydroxybenzoyl) -N '
-N-octanoylmethylenediamine, N- (4-hydroxybenzoyl) -N'-n-tetradecanoylmethylenediamine, N- (4-hydroxybenzoyl)-
N'-n-octadecanoylmethylenediamine, N-
(2,4-Dihydroxybenzoyl) -N'-n-tetradecanoylmethylenediamine, N- (2,4-dihydroxybenzoyl) -N'-n-octadecanoylmethylenediamine, N- (4-hydroxybenzoyl) −
N'-n-octylaminocarbonylmethylenediamine, N- (4-hydroxybenzoyl) -N'-n-dodecylaminocarbonylmethylenediamine, N- (4-
Hydroxybenzoyl) -N'-n-tetradecylaminocarbonylmethylenediamine, N- (4-hydroxybenzoyl) -N'-n-octadecylaminocarbonylmethylenediamine, N- (2,4-dihydroxybenzoyl) -N'- n-octadecylaminocarbonylmethylenediamine, N- (4-hydroxybenzoyl)-
N'-n-tetradecyloxycarbonylmethylenediamine, N- (4-hydroxybenzoyl) -N'-n-
Octadecyloxycarbonyl methylenediamine, N-
(2,4-dihydroxybenzoyl) -N'-n-tetradecyloxycarbonylmethylenediamine, N-
(2,4-dihydroxybenzoyl) -N'-n-octadecyloxycarbonylmethylenediamine, N- (4
-Hydroxybenzoyl) -N'-n-octylhydrazinocarbonylmethylenediamine, N- (4-hydroxybenzoyl) -N'-n-dodecylhydrazinocarbonylmethylenediamine, N- (2,4-dihydroxybenzoyl) -N '-N-tetradecylhydrazinocarbonylmethylenediamine, N- (2,4-dihydroxybenzoyl) -N'-n-octadecylhydrazinocarbonylmethylenediamine,

Nn-octadecyl-2- (p-hydroxyphenylthio) acetamide, Nn-octadecyl-3- (p-hydroxyphenylthio) propanamide, Nn-decyl-11- (p-hydroxy Phenylthio) undecane amide, N- (pn-octylphenyl) -6- (p-hydroxyphenylthio) hexanamide, Nn-octadecyl-p- (p-hydroxyphenylthio) benzamide, N- [2 -(P-Hydroxyphenylthio) ethyl] -n-octadecanamide, N- [p- (p-hydroxyphenylthio) phenyl] -n-octadecanamide, N- (p-hydroxyphenylthio) methyl-N'- n-octadecyl urea,
N- [2- (p-hydroxyphenylthio) ethyl]-
N'-n-tetradecyl urea, N- [2- (p-hydroxyphenylthio) ethyl] -N'-n-octadecyl urea, N- [2- (3,4-dihydroxyphenylthio) ethyl] -N ' -N-octadecyl urea, N- [p
-(P-hydroxyphenylthio) phenyl] -N'-
n-octadecyl urea, N- [10- (p-hydroxyphenylthio) decyl] -N'-n-decyl urea, N-
[2- (p-hydroxyphenylthio) ethyl] carbamate-n-octadecyl, N- [p- (p-hydroxyphenylthio) phenyl] carbamate-n-dodecyl, Nn-octadecylcarbamate- [2 -(P-
Hydroxyphenylthio) ethyl], N- [3- (p-
Hydroxyphenylthio) propionyl] -N-n-octadecanoylamine, N- [2- (p-hydroxyphenylthio) aceto] -N'-n-octadecanohydrazide, N- [3- (p-hydroxy) Phenylthio) propiono] -N'-n-octadecanohydrazide, N-
[3- (3,4-dihydroxyphenylthio) propiono] -N'-n-octadecanohydrazide, N- [6-
(P-Hydroxyphenylthio) hexano] -N'-n
-Tetradecanohydrazide, N- [6- (p-hydroxyphenylthio) hexano] -N'-n-octadecanohydrazide, N- [6- (p-hydroxyphenylthio) hexano] -N '-( pn-octylbenzo) hydrazide, N- [11- (p-hydroxyphenylthio) undecano-N'-n-decanohydrazide, N-
[11- (p-hydroxyphenylthio) undecano-
N'-n-tetradecanohydrazide, N- [11- (p
-Hydroxyphenylthio) undecano-N'-n-octadecanohydrazide, N- [11- (p-hydroxyphenylthio) undecano-N '-(6-phenyl) hexanohydrazide, N- [11- (3 , 4,5-Trihydroxyphenylthio) undecano] -N'-n-octadecanohydrazide, N- [p- (p-hydroxyphenylthio) benzo] -N'-n-octadecanohydrazide, N- [P- (p-hydroxyphenylthiomethyl)
Benzo] -N'-n-octadecanohydrazide, N-
[3- (p-hydroxyphenylthio) propyl] -N
'-N-octadecyl oxamide, N- [3- (3,4
-Dihydroxyphenylthio) propyl] -N'-n-
Octadecyl oxamide, N- [11- (p-hydroxyphenylthio) undecyl] -N'-n-decyl oxamide, N- [p- (p-hydroxyphenylthio) phenyl] -N'-n-octadecyl oxamide, N-
[2- (p-hydroxyphenylthio) acetyl] -N
'-N-octadecyl urea, N- [3- (p-hydroxyphenylthio) propionyl] -N'-n-octadecyl urea, N- [2- (p-hydroxyphenylthio)
Ethyl] -N'-n-octadecanoyl urea, N- [p
-(P-hydroxyphenylthio) phenyl] -N'-
n-octadecanoyl urea, 3- [3- (p-hydroxyphenylthio) propionyl] carbazic acid-n-octadecyl, 4- [2- (p-hydroxyphenylthio) ethyl] -1-n-octadecyl semicarbazide,
1- [2- (p-hydroxyphenylthio) ethyl]-
4-n-octadecyl semicarbazide, 1- [p- (p
-Hydroxyphenylthio) phenyl] -4-n-tetradecyl semicarbazide, 1- [3- (p-hydroxyphenylthio) propionyl] -4-n-octadecyl semicarbazide, 1- [p- (p-hydroxyphenylthio) Benzoyl] -4-n-octadecyl semicarbazide, 4- [2- (p-hydroxyphenylthio) ethyl] -1-n-tetradecanoyl semicarbazide, 4-
[P- (p-hydroxyphenylthio) phenyl] -1
-N-octadecanoyl semicarbazide, 1- [2-
(P-Hydroxyphenylthio) acetamide] -1-
n-octadecanoylaminomethane, 1- [11- (p
-Hydroxyphenylthio) undecanamide] -N '
-N-decanoylaminomethane, 1- [p- (p-hydroxyphenylthio) benzamide] -1-n-octadecanoylaminomethane, 1- [3- (p-hydroxyphenylthio) propanamide] -1 -(N'-n-octadecylureido) methane, 1- [11- (p-hydroxyphenylthio) undecanamide] -N '-(N
'-N-decylureido) methane, 1- {N'-[2-
(P-Hydroxyphenylthio) ethyl] ureido}-
1-n-octadecanoylaminomethane, N- [2-
(P-Hydroxyphenylthio) ethyl] -N'-n-
Octadecyl malonamide,

N- [2- (p-hydroxyphenyl) ethyl] carbamate-n-octadecyl, Nn-octadecylcarbamate- [2- (p-hydroxyphenyl) ethyl], N- [3- (p -Hydroxyphenyl)
Propionyl] -N-n-octadecanoylamine, N
-[6- (p-hydroxyphenyl) hexanoyl]-
N-n-octadecanoylamine, N- [3- (p-hydroxyphenyl) propionyl] -N- (pn-octylbenzoyl) amine, N- [2- (p-hydroxyphenyl) aceto] -N '-N-dodecanohydrazide, N- [2- (p-hydroxyphenyl) aceto]-
N'-n-octadecanohydrazide, N- [3- (p-
Hydroxyphenyl) propiono] -N'-n-octadecanohydrazide, N- [3- (p-hydroxyphenyl) propiono] -N'-n-docosanohydrazide, N
-[6- (p-hydroxyphenyl) hexano] -N '
-N-tetradecanohydrazide, N- [6- (p-hydroxyphenyl) hexano] -N'-n-octadecanohydrazide, N- [6- (p-hydroxyphenyl) hexano] -N '-( p-n-octylbenzo) hydrazide, N- [11- (p-hydroxyphenyl) undecano-N'-n-decanohydrazide, N- [11- (p-
Hydroxyphenyl) undecano-N'-n-octadecanohydrazide, N- [p- (p-hydroxyphenyl) benzo] -N'-n-octadecanohydrazide, N
-[P- (p-hydroxyphenylmethyl) benzo]-
N'-n-octadecanohydrazide, N- [3- (p-
Hydroxyphenyl) propyl] -N'-n-octadecyloxamide, N- [3- (3,4-dihydroxyphenyl) propyl] -N'-n-octadecyloxamide, N- [p- (p-hydroxyphenyl) ) Phenyl]
-N'-n-octadecyl oxamide, N- [2- (p
-Hydroxyphenyl) acetyl] -N'-n-octadecylurea, N- [3- (p-hydroxyphenyl) propionyl] -N'-n-octadecylurea, N- [p
-(P-Hydroxyphenyl) benzoyl] -N'-n
-Octadecyl urea, N- [2- (p-hydroxyphenyl) ethyl] -N'-n-octadecanoyl urea, 4
-[2- (p-hydroxyphenyl) ethyl] -1-n
-Octadecyl semicarbazide, 1- [2- (p-hydroxyphenyl) ethyl] -4-n-tetradecyl semicarbazide, 1- [2- (p-hydroxyphenyl) ethyl] -4-n-octadecyl semicarbazide, 1-
[2- (p-hydroxyphenyl) acetyl] -4-n
-Tetradecyl semicarbazide, 1- [3- (p-hydroxyphenyl) propionyl] -4-n-octadecyl semicarbazide, 1- [11- (p-hydroxyphenyl) undecanoyl] -4-n-decyl semicarbazide, 4- [ 2- (p-hydroxyphenyl) ethyl]-
1-n-octadedecanoyl semicarbazide, 4- [p
-(P-hydroxyphenyl) phenyl] -1-n-octadecanoyl semicarbazide, 1- [2- (p-hydroxyphenyl) acetamido] -1-n-octadecanoylaminomethane, 1- [3- (p -Hydroxyphenyl) propanamide] -1-n-octadecanoylaminomethane, 1- [2- (p-hydroxyphenyl) acetamide] -1- (3-n-octadecylureido)
Methane, 1- [3- (p-hydroxyphenyl) propanamide] -1- (3-n-octadecylureido) methane, 1- [11- (p-hydroxyphenyl) undecaneamide] -1- (3-n -Decylureido) methane, 1- {3- [2- (p-hydroxyphenyl) ethyl] ureido} -1-n-octadecanoylaminomethane, N- [2- (p-hydroxyphenyl) ethyl]-
N'-n-octadecyl malonamide,

4-n-octadecylaminophenol,
4- (1-octadecynyl) phenol, 4- (1,3
-Octadecadiynyl) phenol and the like.

These may be used alone or in admixture of two or more, and usually 5 to 5000% by weight, preferably 10 to 3000% by weight, based on the colorless or light-colored electron-donating dye precursor. Used.

It is also possible to add a binder to the reversible thermosensitive recording layer for the purpose of improving the strength of the reversible thermosensitive recording layer. Specific examples of the binder include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic. Water-soluble polymer such as acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, polyvinyl acetate, polyurethane, polyacrylic acid Examples include, but are not limited to, latex such as ester, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, and the like. No.

A heat-fusible substance may be contained in the reversible thermosensitive recording layer as an additive for controlling the color developing sensitivity and the decoloring temperature of the reversible thermosensitive recording layer. 60 ° C
Those having a melting point of ~ 200 ° C are preferable, and especially 80 ° C.
Those having a melting point of ˜180 ° C. are preferred. It is also possible to use a sensitizer which is used in general thermal recording paper. For example, waxes such as N-hydroxymethylstearic acid amide, stearic acid amide and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2. -Bis (3-
Polyether compounds such as methylphenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, bis (p-methylbenzyl oxalate) Carbonic acid such as ester or oxalic acid diester derivative may be added in combination, but the addition is not limited thereto.

Examples of the electron beam curable resin or the ultraviolet curable resin used in the present invention include compounds having an ethylenically unsaturated bond. More specifically, the following resins are mentioned.

(1) Poly (meth) acrylate of aliphatic, alicyclic, aromatic, araliphatic polyhydric alcohol and polyalkylene glycol (2) of aliphatic, alicyclic, aromatic, araliphatic Poly (meth) acrylate of polyhydric alcohol obtained by adding alkylene oxide to polyhydric alcohol (3) Polyester poly (meth) acrylate (4) Polyurethane poly (meth) acrylate (5) Epoxy poly (meth) acrylate (6) Polyamide Poly (meth) acrylate (7) Poly (meth) acryloyloxyalkyl phosphate ester (8) Vinyl- or diene-based compound having a (meth) acryloyloxy group at the side chain or terminal (9) Monofunctional (meth) acrylate , Vinylpyrrolidone, (meth) acryloyl compound (10) Ethylenic fatigue Cyano compound having a bond (11) Mono- or polycarboxylic acid having an ethylenically unsaturated bond, and their alkali metal salts, ammonium salts, amine salts, etc. (12) Ethylenically unsaturated (meth) acrylamide or alkyl-substituted (meth) ) Acrylamide and its multimers (13) Vinyllactam and polyvinyllactam compounds (14) Polyether having ethylenically unsaturated bond and its ester (15) Alcohol ester having ethylenically unsaturated bond (16) Ethylenically unsaturated Polyalcohol having bond and ester thereof (17) Aromatic compound having one or more ethylenically unsaturated bond such as styrene and divinylbenzene (18) Polyorganosiloxane having (meth) acryloyloxy group in side chain or terminal Service (19) Silicone compound having ethylenically unsaturated bond (20) Multimer or oligoester (meth) acrylate-modified product of the compound described in (1) to (19) above

These resins can be used alone or in combination with other resins. Further, it may be applied without a solvent, may be diluted with a solvent and applied, or may be applied, dried and cured in an emulsion state before use.

[0067] The coating amount of the electron beam curing resin or an ultraviolet curable resin is thinner for the purpose of avoiding thermal shutdown is ^{desired, 0.5g / m 2 ~10.0g / m} 2 is preferred. If it is less than this range, good repeatability is not expressed,
If it is more than this range, the heat sensitivity is deteriorated.

As a method for applying the resin for forming the electron beam or ultraviolet ray curable resin layer of the present invention, a gravure roll and transfer roll coater, a bar coater,
Roll coater, air knife coater, U comma coater, AKKU coater, smoothing coater, micro gravure coater, air knife coater, reverse roll coater, 4 or 5 roll coater, blade coater, dip coater, bar coater, rod coater, kiss coater, gate Any coater such as a roll coater, a squeeze coater, a falling curtain coater, a slide coater, or a die coater may be used.

When the electron beam curing method is used in the present invention, the electron beam irradiation is performed at an accelerating voltage of 100 to 100 in terms of transmission power and curing power.
1000 kV, more preferably 100-300 kV
Using a V electron beam accelerator, the absorbed dose in one pass is 0.5
It is preferably set to be about 20 Mrad. If the accelerating voltage or the electron beam irradiation dose is lower than this range, the electron beam penetrating power is too low to perform sufficient curing, and if it is higher than this range, not only the energy efficiency deteriorates, but also the resin, There are unfavorable effects on quality such as decomposition of additives and reduction of strength of base paper.

The electron beam accelerator may be, for example, an electro curtain system, a scanning type, a double scanning type or the like.

During electron beam irradiation, if the oxygen concentration is high, the curing of the electron beam curable resin is hindered, so nitrogen,
Oxygen concentration is 600ppm or less, preferably 400p by performing replacement with an inert gas such as helium or carbon dioxide.
Irradiation is preferably performed in an atmosphere suppressed to pm or less.

When the resin is cured by the ultraviolet curing method in the present invention, a photoreaction initiator is mixed and used. Examples of the photoinitiator include acetophenones such as di- and trichloroacetophenone, benzophenone, Michler's ketone, benzyl, benzoin, benzoin alkyl ether, benzyl dimethyl ketal, tetramethyl thiuram monosulfide, thioxanthones, azo compounds and various silver salts. The amount of the photoreaction initiator used is usually in the range of 0.1 to 10% with respect to the ultraviolet curable resin. Storage stabilizers such as hydroquinone may also be used as the photoinitiator.

Examples of the ultraviolet irradiation device include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, and an ozoneless type that generates less ozone. Generally, a plurality of lamps having an output of 30 w / cm or more are used in parallel.

The reversible thermosensitive recording material of the present invention comprises a reversible thermosensitive recording layer and a protective layer, if necessary, in order to prevent deterioration of the reversible thermosensitive recording layer by other than heating, such as light and a plasticizer. An intermediate layer can be provided between them.

The reversible thermosensitive recording layer may contain a colorless or light-colored dye precursor and a reversible color developer in the following manner.
A method of dissolving or dispersing each compound alone in water or an organic solvent, a method of dissolving or dispersing each compound in water or an organic solvent, heating and dissolving each compound to homogenize and then cooling, There is a method of mixing respective solutions or dispersions obtained by a method of dissolving or dispersing in water or an organic solvent, printing on a support and coating and drying. In this case, for example, each color-forming component may be contained in one layer to form a multilayer structure, but the invention is not particularly limited thereto.

The support used in the reversible thermosensitive recording material of the present invention includes paper, coated paper, various non-woven fabrics, woven fabrics, synthetic resin films, synthetic resin laminated papers, synthetic papers, metal foils, glass and the like, or A composite sheet in which these are combined can be arbitrarily used according to the purpose, and may be transparent, translucent or opaque, but is not limited thereto. The thickness of the support is
The range is not particularly limited as long as it can withstand repeated use, but is 20 to 1300 μm, preferably 40 to 1000 μm.
m.

The layer structure of the reversible thermosensitive recording material of the present invention is as follows:
An intermediate layer may be provided between the reversible thermosensitive recording layer and the support and / or between the reversible thermosensitive recording layer and the protective layer. In this case, the intermediate layer may be composed of a plurality of layers of 2 layers or 3 layers or more. Further, information can be recorded electrically, magnetically, or optically in the reversible thermosensitive recording layer and / or on the surface provided with another layer and / or the reversible thermosensitive recording layer and / or on the opposite surface. The material may be included.
Further, a back coat layer may be provided on the surface opposite to the surface on which the reversible thermosensitive recording layer is provided, for the purpose of preventing curl and antistatic, and may further be subjected to an adhesive processing or the like.

For the reversible thermosensitive recording layer and / or the intermediate layer, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide,
Pigments such as zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, and others, zinc stearate,
Higher fatty acid metal salts such as calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearamide, castor wax, dispersants such as sodium dioctylsulfosuccinate, surfactants, fluorescent dyes, etc. Can also be included.

The method of forming each layer constituting the reversible thermosensitive recording material of the present invention on the support is not particularly limited, and it can be formed by a conventional method. For example, a smearing device such as an air knife coater, a blade coater, a bar coater, and a carten coater, a planographic printing plate, a relief printing plate,
It is possible to use various printing machines using intaglio, flexo, gravure, screen, hot melt and the like. Furthermore, in addition to the usual drying process, each layer can be held by UV irradiation / EB irradiation. By these methods, one layer or multiple layers can be smeared and printed simultaneously.

In the reversible thermosensitive recording material of the present invention, in order to form a color recorded image, rapid cooling following heating is required, and in order to erase the recorded image, the cooling rate after heating is set. It's good if it's late. For example, the color-developed state can be developed by heating the material by an appropriate method and then rapidly cooling it by pressing a low-temperature metal block or the like. In addition, when a thermal head, a laser beam or the like is used for heating for an extremely short period of time, it is cooled immediately after the heating is completed, so that the coloring state can be maintained. On the other hand, when heated with an appropriate heat source (thermal head, laser light, heat roll, heat stamp, high frequency heating, radiant heat from a light source such as a tungsten lamp or halogen lamp, hot air, etc.) for a relatively long time, recording Since not only the layer but also the support and the like are heated, even if the heat source is removed, the cooling speed is slow and the state is decolorized. Therefore, even if the same heating temperature and / or the same heat source is used, the colored state and the decolored state can be arbitrarily expressed by controlling the cooling rate.

[0081]

The present invention will be described in more detail with reference to the following examples.

Example 1 (A) Preparation of reversible heat-sensitive coating liquid 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3-yl) which is a dye precursor -4-Azaphthalide 40 parts 2.5%
It was pulverized with a ball mill for 24 hours together with 90 parts of an aqueous polyvinyl alcohol solution to obtain a dye precursor dispersion. Then N-
[3- (p-hydroxyphenyl) propiono] -N '
100 parts of n-octadecanohydrazide was ball milled together with 400 parts of 2.5% polyvinyl alcohol aqueous solution.
The dispersion was obtained by pulverizing for 4 hours. After mixing the above two kinds of dispersions, 200 parts of a 10% polyvinyl alcohol aqueous solution and 400 parts of water were added and mixed well to prepare a reversible heat-sensitive coating liquid.

(B) Preparation of reversible heat-sensitive recording layer and intermediate layer The reversible heat-sensitive coating solution prepared in (A) was applied to a polyethylene terephthalate (PET) sheet to give a solid content of 4 g / m ^2.
And 5% polyvinyl alcohol were smeared and dried to give a solid content of 1 g / m ² to obtain an intermediate layer.

(C) Preparation of protective layer of UV-curable resin On the intermediate layer obtained in (B), UV-curable resin (Aronix M8030, product of Toagosei Chemical Industry Co., Ltd.) 5
Part, N-vinyl-2-pyrrolidone 5 parts, and 5 parts of a photoinitiator (IRGACURE 500, a product of Nippon Ciba Geigy Co., Ltd.) were mixed well (a), and further hydrophobic silica (Syrohobic 100 (average particle Diameter 1.4 μm), product of Fuji Silysia K.K., SS-70 (average particle size 4.1 μm)
m), a product of Nippon Silica Industry Co., Ltd., P-363 (average particle size: 10.5 μm), a product of Mizusawa Chemical Industry Co., Ltd.) in the proportions shown in Table 1, and sufficiently stirred to give 2.5 g / m 2. After applying ² to make the UV irradiation device (Ushio Electric Co., Ltd.)
Manufactured, rapid cure) to obtain a reversible thermosensitive recording material.

[0085]

[Table 1]

Comparative Example 1 As a comparative example of Example 1, one in which no hydrophobic silica was added was prepared in the same manner as in (C) of Example 1.

[0087]

[Table 2]

Example 2 On the intermediate layer obtained in (B) of Example 1, an electron beam curable resin (KAYARADR167, manufactured by Nippon Kayaku Co., Ltd.) was added to the hydrophobic silica particles (silos) at the ratio shown in Table 3. Hovic 10
0 (average particle size 1.4 μm), Fuji Silysia K.K. product, SS-70 (average particle size 4.1 μm), Nippon Silica Industry Co., Ltd. product, P-363 (average particle size 10.5 μm)
m), a product of Mizusawa Chemical Industry Co., Ltd.) and mixed, and agitated electron beam curable resin was applied to 2.5 g / m ^2, and then the oxygen concentration in the electron beam irradiation chamber was changed to nitrogen gas. A reversible thermosensitive recording material was introduced by introducing it into an electron beam irradiation device (made by Nisshin High Voltage Co., Ltd., product name Curetron) whose concentration was reduced to 200 ppm or less and irradiating it with an electron beam accelerating voltage of 200 kV and an absorbed dose of 2 Mrad. Obtained.

[0089]

[Table 3]

Comparative Example 2 As a comparative example of Example 2, one in which no hydrophobic silica was added was prepared in the same manner as in Example 2.

[0091]

[Table 4]

Test 1 The reversible thermosensitive recording materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were mixed with Kyocera print head KJT-256-8MGF.
Okura Electric Thermal Printing Tester TH-P with 1
Print using an MD with an applied pulse of 2.0 ms under the condition of an applied voltage of 26 V, put the sample in a constant temperature dryer kept at 120 ° C, erase the image, and print again. Repeated up to times. Then, the erased portion was measured for L ^* a ^* b ^* with a color difference meter (CR-100, manufactured by Minolta Co., Ltd.).

The degree of yellowing of the erased portion is represented by the b ^* value of L ^* a ^* b ^* . That is, when the b ^* value is positive and takes a large value as compared with the non-image portion (background portion), it is visually recognized as yellowing. The [Delta] b ^* as the degree of yellowing from this - was defined as the (b ^* of the erased portion b ^* of the non-image portion). The results are shown in Table 5.

[0094]

[Table 5]

From Table 5, values of Examples 1 to 2 1-4, 6 to 9 are smaller than Comparative Examples 1 and 2 5 and 10, that is, hydrophobic silica is effective in suppressing yellowing. Actually, the yellowing of the decolorized portion of the example is hardly visible, but in the comparative example, the decolorized portion is visually recognized in the yellowed state.

Comparative Example 3 On the intermediate layer obtained in (B) of Example 1, an ultraviolet curable resin (Aronix M8030, Toagosei Kagaku Kogyo Co., Ltd.) was used.
Product) 5 parts, N-vinyl-2-pyrrolidone 5 parts, photoinitiator (IRGACURE 500, Japan Ciba Geigy Co., Ltd.)
(Manufactured by the same company) 5 parts were mixed well ((C) of Example 1 and the same composition as Aronix mixture (a)), and further aluminum hydroxide (H-42, particle size 1 μm, Showa Denko KK product), Amorphous silica (Mizukasil P-527, particle size 1.
6 μm, Mizusawa Chemical Co., Ltd. product), Zinc oxide (Zinc Hua No. 1, particle size 0.3-0.6 μm, Kasho Co., Ltd. product), Kaolin (UW-90, particle size 2 μm or less, Hishisan) Shoji Co., Ltd.
One of the products) is mixed in the following proportions, thoroughly stirred and applied so as to have a concentration of 2.5 g / m ² , followed by curing with an ultraviolet irradiation device (Rapid Cure, manufactured by Ushio Electric Co., Ltd.). A reversible thermosensitive recording material was obtained.

[0097]

[Table 6]

Test 2 The reversible heat-sensitive recording material obtained in Example 3 was applied with an applied pulse of 1.1 milliseconds using a heat-sensitive facsimile printing tester TH-PMD manufactured by Okura Electric with a print head KJT-256-8MGF1 manufactured by Kyocera. Printing was performed under the condition of an applied voltage of 26 V, and the density of the obtained image portion (coloring portion) was measured by a densitometer Macbeth RD9.
18 was used for measurement. Further, the operation of putting the sample in a constant temperature dryer kept at 120 ° C., erasing the image and printing again was repeated up to 20 times. The results are shown in Table 1.

[0099]

[Table 7]

Test 3 The reversible thermosensitive recording material obtained in Comparative Example 3 was applied with an applied pulse of 2.0 milliseconds using a thermal facsimile printing tester TH-PMD manufactured by Okura Electric Co. with a print head KJT-256-8MGF1 manufactured by Kyocera. Printing was performed under the condition of an applied voltage of 26 V, and the operation of putting the sample in a constant temperature dryer kept at 120 ° C., erasing the image and printing again was repeated up to 5 times. Then, the erased portion was measured for L ^* a ^* b ^* with a color difference meter (CR-100, manufactured by Minolta Co., Ltd.).

The degree of yellowing of the erased portion is represented by the b ^* value of L ^* a ^* b ^* . That is, when the b ^* value is positive and takes a large value as compared with the non-image portion (background portion), it is visually recognized as yellowing. The [Delta] b ^* as the degree of yellowing from this - was defined as the (b ^* of the erased portion b ^* of the non-image portion). The results are shown in Table 8.

[0102]

[Table 8]

From Tests 2 and 3, it is understood that there is no effect of suppressing yellowing other than silicas. Further, from Test 2, in the case of silica which is not hydrophobic silica, although there is some effect of suppressing yellowing, the density of the image area is reduced during repeated color development / erasing, which is one of the objects of the present invention, stable images. Formation has not been achieved.

[0104]

EFFECTS OF THE INVENTION As in Examples 1 and 2, by incorporating hydrophobic silica into the protective layer, yellowing is reduced,
It was possible to obtain a reversible thermosensitive recording material capable of forming a stable image even when repeatedly colored / erased.

Claims (2)

[Claims] 1. A usually colorless or pale-colored electron-donating dye precursor on at least one side of a support, and a reversible developer that causes the dye precursor to develop color and is reheated to erase the color. In the reversible thermosensitive recording material provided with a reversible thermosensitive recording layer containing the above, the average particle size is 1 to 10 μm on the reversible thermosensitive recording layer or on at least one intermediate layer
A reversible thermosensitive recording material comprising a protective layer made of an ultraviolet curable or electron beam curable resin containing m hydrophobic silica particles. 2. The reversible thermosensitive recording material according to claim 1, wherein a protective layer made of an ultraviolet curable or electron beam curable resin containing 3 to 30% by weight of hydrophobic silica particles is provided.