JP2003211840A - Reversible heat-sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material in which formation and erasing of an image are possible by a good contrast and a stable image can be held with time under an environment of an ordinary life and more practically, to provide a reversible heat-sensitive recording material with excellent erasing properties and low ground skin density and in which there exists no possibility of generating change in hue and inferiority of color erasing of a color developing part, color redevelopment of an erasing part, coloring of the ground skin and the like and having high light-resistance. <P>SOLUTION: In the reversible heat-sensitive recording material comprising a colorless or light-colored dye precursor and a reversible color developer which generates a reversible change in color tone to the dye precursor based on difference in heating temperature or cooling speed after heating, the reversible heat- sensitive recording material can form and erase the image with a clear contrast and can hold the image with excellent light-resistance and being stable with time by comprising at least one kind of compounds containing at least two groups with an N,N-disubstituted hydrazine structure in the same molecule in the recording material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible heat-sensitive recording material capable of forming and erasing an image by controlling heat energy.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording material is a heat-sensitive recording material containing, on a support, an electron-donating colorless or light-colored dye precursor (hereinafter also referred to as a leuco dye) and an electron-accepting color developer. A layer is provided, and 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.
No. 160, Japanese Patent Publication No. 45-14039, etc.

In general, such a heat-sensitive recording material cannot erase the part once an image is formed and return it 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, a reversible thermosensitive recording material capable of repeating image formation and image erasing has been devised in order to deal with such a problem. For example, Japanese Patent Laid-Open No. 54-119377.
JP-A-63-39377, JP-A-63-
Japanese Patent No. 41186 describes a heat-sensitive recording material composed of a resin base material and organic low-molecular substances 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 state of image formation and deletion Since the temperatures for holding the states are different, it is not possible to hold these two states stably for an arbitrary period at room temperature.

Further, Japanese Patent Laid-Open No. 59-120492 discloses a method of maintaining an image forming state and an erasing state by keeping the recording material in a hysteresis temperature region by utilizing the hysteresis characteristic of a coloration component. However, this method requires a heating source and a cooling source for image formation and erasure, and has the drawback that the temperature range in which the image formation state and erasure state can be maintained is limited to the hysteresis temperature range. It is still insufficient for use in the temperature environment.

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. 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. Also,
Since the decoloring action of the basic group also acts on the color development part 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 which develops and decolorizes a leuco dye by heating, and an organic phosphonic acid compound, α-hydroxy aliphatic compound as an electron accepting compound. Specific phenol compounds such as carboxylic acids, fatty acid dicarboxylic acids, and alkylthiophenols having an aliphatic group having 12 or more carbon atoms, alkyloxyphenols, alkylcarbamoylphenols, and gallic acid alkylesters are exemplified. However, even with this recording medium, the two problems of low color density or incomplete decolorization cannot be solved at the same time, and the temporal stability of the image should be practically satisfactory. Absent. Further, in JP-A-5-294063, various types of esters of fatty acids, waxes, higher alcohols, phosphoric acid / benzoic acid / phthalic acid or oxyacids are used as decoloring accelerators for improving the erasability of the reversible thermosensitive recording medium. , Silicone oils, liquid crystal compounds, surfactants, and fatty acid saturated hydrocarbons having 10 or more carbon atoms have been disclosed. However, their effects are small and the image density at the time of erasure is still high, which is not practical.

The applicant of the present invention has been disclosed in Japanese Patent Laid-Open No. 6-210
No. 954 and Japanese Patent Application Laid-Open No. 7-179043,
By using a specific phenolic compound as a reversible color developer and combining it with a leuco dye, it is possible to repeatedly form and erase images with good contrast, and to obtain stable images over time in the environment of everyday life. We proposed a reversible thermosensitive recording material of high practicability that can hold the temperature. However, in such a reversible thermosensitive recording material, it cannot be said that it is always stable against light, and when the recording material is irradiated with light such as sunlight or a fluorescent lamp for a long time, the color-developed portion is erased. At that time, the density does not drop to the same level as the background part,
There was a problem in light resistance such as a change in the color tone of the colored part and coloring of the background part.

The problem of light resistance of such a recording material is as follows.
The method of incorporating an antioxidant into the reversible thermosensitive recording layer is generally used. An ultraviolet absorber typified by a benzophenone compound, a benzotriazole compound, a salicylic acid compound, a phenolic antioxidant, or an amine antioxidant is used. A method of incorporating a radical chain inhibitor typified by an inhibitor in combination with a reversible thermosensitive recording layer is disclosed in Japanese Patent Laid-Open No. 6-1.
It has already been proposed in Japanese Patent Publication No. 066. However, in order to obtain the effect of light resistance by incorporating these antioxidants into the reversible thermosensitive recording layer, it is necessary to add them at a very high concentration to the dye precursor. When such a reversible thermosensitive recording material is stored for a long time, the antioxidant is crystallized in the recording layer and further migrates to the surface of the reversible thermosensitive recording layer (hereinafter, also referred to as bleed-out). There was a problem that the effect weakened. Further, there is also a problem that the image stability and the erasing property are deteriorated due to the interaction between the antioxidant and the dye precursor.

Then, a long-chain aliphatic hydrocarbon compound containing a hetero atom is disclosed in JP-A-11-70731.
A reversible thermosensitive recording material has been proposed which contains a specific compound as a coloring and decoloring control agent and also has improved light resistance, but this reversible thermosensitive recording material improves the erasability of the colored portion by light irradiation. However, the problem of re-coloring in which the decolored part is colored and emerges and the problem of coloring the background part still remain.

[0012] On the other hand, the present applicants have so far proposed JP-A-1
No. 0-211767 discloses a reversible thermosensitive recording material in which a phenol compound having a specific substituent is contained as an antioxidant to improve light resistance, but this also has the same problem as described above. There was room for further improvement.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording material capable of forming / erasing an image with good contrast and capable of holding a stable image over time in an environment of daily life. It is a thing. More specifically, it has excellent erasability, has a low background density, and has high light resistance that does not cause changes in hue of the colored area due to light exposure, defective decoloring, recoloring of the decolored area, and coloring of the background. An object of the present invention is to provide a reversible thermosensitive recording material.

[0014]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, firstly, a reversible color tone change occurs in the dye precursor due to the difference between the colorless or light-colored dye precursor on the support and the heating temperature and / or the cooling rate after heating. A reversible thermosensitive recording material containing a reversible developer, which contains at least one compound having two or more groups having an N, N-disubstituted hydrazine structure in the same molecule. A reversible thermosensitive recording material is provided which is characterized by

Second, a reversible color development that causes a reversible color change in the dye precursor due to the difference in the heating temperature and / or the cooling rate after heating from the colorless or light-colored dye precursor on the support. A reversible thermosensitive recording material containing an agent, wherein the recording material contains at least one compound represented by the following general formula (1), (2) or (3). A heat-sensitive recording material is provided.

[0016]

[Chemical 5]

In the formula 1, R ¹ and R ² may be the same or different and each represents a hydrocarbon group which may have a substituent, and R ¹ and R ² are connected to each other to form a ring. May be formed. X ¹ represents an oxygen atom or a sulfur atom.
n represents an integer of 2 to 5. A ¹ represents an n-valent organic residue. The n parenthesized partial structures bonded to A ¹ may be the same or different.

[0018]

[Chemical 6]

In formula 2, R ³ and R ^{4, which} may be the same or different, each represents a hydrocarbon group which may have a substituent, and R ³ and R ⁴ are linked to each other to form a ring. May be formed. X ² represents a divalent group containing a hetero atom. m represents an integer of 2 to 5. A ² represents an m-valent organic residue. A ² represents an m-valent organic residue. The m parenthesized partial structures bonded to A ² may be the same or different.

[0020]

[Chemical 7]

In the formula 3, R ⁵ and R ⁶ may be the same or different and each represents a hydrocarbon group which may have a substituent, and R ⁵ and R ⁶ are linked to each other to form a ring. May be formed. R ⁷ represents a hydrocarbon group which may have a substituent. X ³ represents an oxygen atom or a sulfur atom. X ⁴
Represents a single bond, an oxygen atom, or a sulfur atom. q represents 2 or 3. Parenthesized q bound to a phosphorus atom
The individual partial structures may be the same or different.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the compound represented by the general formula (1), R ¹ and R ² may be the same or different and each represents a hydrocarbon group which may have a substituent. May be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or a hydrocarbon group composed of both of them.
The aliphatic hydrocarbon group may be linear or branched, may have an unsaturated bond, and may further form a ring. Examples of the substituent bonded to the hydrocarbon group include an alkoxy group, an alkylthio group, a hydroxyl group and a halogen atom. Preferably, R ¹ and R ² are monovalent hydrocarbon groups having 1 to 8 carbon atoms, and examples thereof include methyl group, ethyl group, isopropyl group, n-hexyl group, allyl group, methallyl group, benzyl group, Examples thereof include a phenethyl group, a phenyl group and a toluyl group, and a methyl group and a phenyl group are particularly preferable.

R ¹ and R ² may be connected to each other to form a ring. It is preferably a 5- to 7-membered heterocyclic ring which may have a substituent, for example, a pyrrolidine ring,
Examples thereof include a piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, and homopiperidine ring, with a piperidine ring, piperazine ring and morpholine ring being particularly preferred.

X ¹ represents an oxygen atom or a sulfur atom,
It is preferably an oxygen atom. n represents an integer of 2 to 5, and is preferably 2 or 3. The n parenthesized partial structures bonded to A ¹ may be the same or different.

A ¹ represents an n-valent organic residue, specifically a hydrocarbon group which may have a substituent and / or a hetero atom, and may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Alternatively, it may be a hydrocarbon group composed of both of them. The aliphatic hydrocarbon group may be linear or branched, may have an unsaturated bond, and may further form a ring. Examples of the substituent bonded to the hydrocarbon group include an alkoxy group, an alkylthio group, a hydroxyl group and a halogen atom. Preferably A ¹ is a substituent and / or
Alternatively, it is a divalent or trivalent hydrocarbon group having 1 to 24 carbon atoms which may have a hetero atom.

A ¹ is a hydrocarbon group which may have a hetero atom, and is preferably a divalent or trivalent hydrocarbon group formed via a biuret bond, a urea bond, an isocyanurate bond or an allophanate bond. It is a base.

Specific examples of preferable compounds represented by the general formula (1) are shown below in Chemical formulas 8 to 11, but the present invention is not limited thereto. In addition, Ph in the exemplified compound represents a phenyl group.

[0028]

[Chemical 8]

[0029]

[Chemical 9]

[0030]

[Chemical 10]

[0031]

[Chemical 11]

In the compound represented by the general formula (2), R ³ and R ⁴ have the same meanings as R ¹ and R ^{2 in} the general formula (1). X ² represents a divalent group containing a hetero atom, and is preferably an oxygen atom, a sulfur atom, an imino group (—NH—), a carbornyl group (—CO—), a sulfinyl group (—SO—), a sulfonyl group (— It represents a divalent group having at least one of SO ₂ —) but excludes an amide group (—CONH—) and a thioamide group (—CSNH—).

M represents an integer of 2 to 5, preferably 2
Or 3. The m parenthesized partial structures bonded to A ² may be the same or different.

A ² represents an m-valent organic residue, specifically a hydrocarbon group which may have a substituent and / or a hetero atom, and may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Alternatively, it may be a hydrocarbon group composed of both of them. The aliphatic hydrocarbon group may be linear or branched, may have an unsaturated bond, and may further form a ring. Examples of the substituent bonded to the hydrocarbon group include an alkoxy group, an alkylthio group, a hydroxyl group and a halogen atom. Preferably A ² is a substituent and / or
Alternatively, it is a divalent or trivalent hydrocarbon group having 1 to 24 carbon atoms which may have a hetero atom.

Specific examples of preferred compounds represented by the general formula (2) are shown below in Chemical formulas 12 to 13, but the present invention is not limited thereto. In addition, Ph in the exemplified compound represents a phenyl group.

[0036]

[Chemical 12]

[0037]

[Chemical 13]

In the compound represented by the general formula (3), R ⁶ and R ⁶ have the same meanings as R ¹ and R ^{2 in} the general formula (1). R ⁷ represents a hydrocarbon group which may have a substituent, and may be an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a hydrocarbon group composed of both of them. The aliphatic hydrocarbon group may be linear or branched, may have an unsaturated bond, and may further form a ring. Examples of the substituent bonded to the hydrocarbon group include an alkoxy group, an alkylthio group, a hydroxyl group and a halogen atom.
Preferably R ⁷ has 1 to 1 carbon atoms which may have a substituent.
24 monovalent hydrocarbon groups.

X ³ represents an oxygen atom or a sulfur atom,
It is preferably an oxygen atom. X ⁴ is a single bond, an oxygen atom,
Alternatively, it represents a sulfur atom. q represents 2 or 3. The q parenthesized partial structures bonded to the phosphorus atom may be the same or different.

Specific examples of preferred compounds represented by the general formula (3) are shown below in Chemical Formula 14, but the present invention is not limited thereto. In addition, Ph in the exemplified compound represents a phenyl group.

[0041]

[Chemical 14]

The preferred addition amount of the compounds represented by the general formulas (1) to (3) is 0.5 to 200% by mass, more preferably 2 to 100% by mass, based on the dye precursor.
If the amount added is too small, the effect of promoting erasure and the effect of improving light resistance will be poor, and if the amount added is too large, the color density will decrease and the image stability during storage will deteriorate. The compounds represented by the general formulas (1) to (3) can be used alone or in combination of two or more.

As the reversible developer used in the present invention, a phenol compound represented by the general formula (4) is used in view of image contrast, image stability, repetitive durability and the like.

[0044]

[Chemical 15]

In the formula 4, X ⁵ and X ⁶ are an oxygen atom, a sulfur atom, or --CONH-- which does not contain a hydrocarbon group at both ends.
It represents a divalent group having a bond as the minimum structural unit. R ⁸ represents a single bond or a divalent hydrocarbon group having 1 to 12 carbon atoms. R
⁹ represents a divalent hydrocarbon group having 1 to 18 carbon atoms. R ¹⁰
Represents a monovalent hydrocarbon group having 1 to 26 carbon atoms. r is 0
Represents an integer of 4 and is repeated when r is 2 or more, R ⁹
And X ⁶ may be the same or different.

In the compound represented by the general formula (4), R ¹⁰ represents a monovalent hydrocarbon group having 1 to 26 carbon atoms, preferably a monovalent hydrocarbon group having 6 to 22 carbon atoms. . R ⁸
Represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. R ⁹ represents a divalent hydrocarbon group having 1 to 20 carbon atoms, preferably a divalent hydrocarbon group having 1 to 12 carbon atoms. R ⁸ , R ⁹ and R ¹⁰ may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or may be a hydrocarbon group composed of both of them. The aliphatic hydrocarbon group may be linear or branched, may have an unsaturated bond, and may further form a ring.

On the other hand, X ⁵ and X ⁶ are oxygen atom, sulfur atom,
Alternatively, it represents a divalent group having a minimum constitutional unit of -CONH- bond containing no hydrocarbon group at both ends, and specific examples thereof include amide (-CONH-, -NHCO-), urea (-NHCONH-). ), Urethane (-NHCOO-,-
OCONH-), diacylamine (-CONHCO
-), Diacyl hydrazide (-CONHNHCO-),
Oxalic acid diamide (-NHCOCONH-), acylurea (-CONHCONH-, -NHCONHCO-),
3-acylcarbazic acid ester (-CONHNHCO
O-), semicarbazide (-NHCONHNH-, -N)
HNHCONH-), acyl semicarbazide (-CON
HNHCONH -, - NHCONHNHCO-), diacyl aminomethane (-CONHCH ₂ NHCO -), 1
-Acylamino-1-ureidomethane (-CONHCH
_{2 NHCONH -, - NHCONHCH 2 NHCO-} ),
Malonamide (-NHCOCH ₂ CONH-), carbohydrazone (-CONHN = CH -, - CH = NNHC
And groups such as O-).

Specific examples of the compound represented by the general formula (4) include the compounds represented by the following chemical formulas 16 and 17, but the present invention is not limited thereto.

[0049]

[Chemical 16]

[0050]

[Chemical 17]

The reversible developer represented by the general formula (4) is
They may be used alone or in admixture of two or more, and the amount of the reversible developer according to the present invention to the colorless or pale dye precursor is 5 to 5000% by mass, preferably 10 to 3000% by mass. %.

The colorless or light-colored dye precursor used in the present invention is represented by a known compound generally used for pressure-sensitive recording paper, heat-sensitive recording paper and the like, but is not particularly limited. Specific examples include the compounds listed below, 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- (4-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (4-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3- (4-diethylamino-2-)
Ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2)
-Methylindol-3-yl) -4-azaphthalide,
3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4,7-Diazaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -7-azaphthalide, 3-
(4-Diethylamino-2-n-hexyloxyphenyl) -3- (1-ethyl-2-methylindole-3-
Yl) phthalide, 3- (4-diethylamino-2-hexyloxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4
-Dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,2-
Dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-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, 3,
3-bis (p-dimethylaminophenyl) -4-azaphthalide and the like.

(2) Diphenylmethane type compounds 4,4'-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenylleuco auramine, N-2,4,5-trichlorophenyl leuco auramine and the like.

(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-phenoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3 , 4-Dichloroanilino) fluorane, 3-diethylamino-7-
(2-chloroanilino) fluorane and the like.

3-Diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-
7-anilinofluorane, 3-dipentylamino-6-
Methyl-7-anilinofluorane, 3- (N-ethyl-
N-p-tolyl) amino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, 3- ( N-methyl-N-propyl) amino-6-methyl-7-anilinofluorane, 3
-(N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-
Methyl-7- (m-toluidino) fluorane, 3- (N
-Methyl-N-cyclohexyl) amino-6-methyl-
7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (m
-Trifluoromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane,
3-dibutylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (o-fluoroanilino) fluorane, 3-dibenzylamino-7- (o-fluoroanilino) fluorane and the like.

(4) Thiazine type compounds benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and the like.

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

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

A specific example of the method for producing the reversible thermosensitive recording material of the present invention comprises a dye precursor and a reversible developer as main components, to which the compound according to the present invention is added and coated on a support. And a reversible thermosensitive recording layer is formed.

As a method for preparing a coating solution for uniformly containing the dye precursor, the reversible color developer and the compound according to the present invention in the reversible thermosensitive recording layer, each compound is dissolved in a solvent or dispersed in a dispersion medium. Method of dispersing and then mixing, method of mixing each compound and then dissolving in solvent or dispersing in solvent, dissolving each compound by heating and homogenizing and then cooling, dissolving in solvent or dispersing in dispersion medium Examples thereof include, but are not limited to, methods. At the time of dispersion, a dispersant may be used if necessary. As the dispersant when water is used as the dispersion medium, water-soluble polymers such as polyvinyl alcohol and various surfactants can be used. A water-soluble organic solvent such as ethanol may be mixed when the aqueous dispersion is performed. In addition to this, when an organic solvent represented by hydrocarbons is a dispersion medium, lecithin, phosphoric acid esters or the like may be used as a dispersant.

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 Ester, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl chloride copolymer, polyvinyl chloride, ethylene Vinylidene chloride copolymers, latexes such as polyvinylidene chloride. The role of these binders is to keep the respective materials of the composition in a uniformly dispersed state without being biased by the application of heat for printing and erasing. Therefore, it is preferable to use a resin having high heat resistance as the binder resin. Recently, high value-added reversible thermosensitive recording materials such as prepaid cards and stored cards are often used, and along with this, high durability products such as heat resistance, water resistance, and adhesiveness are required. Is becoming. Curable resins are particularly preferable for such requirements.

Examples of the curable resin include a thermosetting resin, an electron beam curing resin, an ultraviolet curing resin and the like.
As the thermosetting resin, for example, phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate resin and the like, which are cured by reacting a hydroxyl group and a carboxyl group with a crosslinking agent, can be mentioned. Examples of the crosslinking agent at this time include isocyanates, amines, phenols, epoxies and the like.

Monomers used for the electron beam and cured resin include monofunctional monomers represented by acrylics, bifunctional monomers, polyfunctional monomers, and the like. In particular, in the case of ultraviolet crosslinking, photopolymerization initiation Agents and photopolymerization accelerators are used.

Further, a heat-fusible substance may be contained in the reversible thermosensitive recording layer as an additive for controlling the color developing sensitivity of the reversible thermosensitive recording layer. Those having a melting point of 60 ° C. to 200 ° C. are preferable, and those having a melting point of 80 ° C. to 180 ° C. are particularly preferable. It is also possible to use a sensitizer which is used in general thermal recording paper. These compounds include N-hydroxymethylstearic acid amide,
Waxes such as behenic acid amide, stearic acid amide, palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, p-benzylbiphenyl, 4-
Biphenyl derivatives such as allyloxybiphenyl, 1,2
-Polyether compounds such as -bis (3-methylphenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, bis (oxalate) Carbonic acid such as p-methylbenzyl) ester or an oxalic acid diester derivative can be used, and it is possible to add two or more kinds in combination.

As the support used in the reversible thermosensitive recording material of the present invention, paper, various non-woven fabrics, woven fabrics, synthetic resin films such as polyethylene terephthalate and polypropylene, paper laminated with synthetic resin such as polyethylene and polypropylene, synthetic Paper, metal foil, glass, etc., or a composite sheet in which these are combined can be optionally used according to the purpose, but is not limited to these.
These may be opaque, semi-transparent or transparent. In order to make the background look white or other specific color, a white pigment, a colored dye or pigment, or bubbles may be contained in the support or on the surface. Especially in the case of aqueous coating such as films, when the hydrophilicity of the support is small and it is difficult to coat the reversible thermosensitive recording layer, the same water-soluble polymer as used for the hydrophilic treatment of the surface by corona discharge or the binder The substance may be subjected to an easy-adhesion treatment such as coating on the surface of the support.

The layer structure of the reversible thermosensitive recording material of the present invention is as follows:
Only the reversible thermosensitive recording layer may be used. If necessary,
Providing a protective layer on the reversible thermosensitive recording layer also provides an intermediate layer containing at least one of water-soluble polymer, white or colored dye or pigment, and hollow particles between the reversible thermosensitive recording layer and the support. It can also be provided. In this case, the protective layer and / or the intermediate layer may be composed of a plurality of layers of 2 layers or 3 layers or more. The reversible thermosensitive recording layer may also be a multi-layered structure having two or more layers by containing each component one by one or changing the compounding ratio for each layer. Further, a material capable of electrically, optically, and magnetically recording information in the reversible thermosensitive recording layer and / or on the surface opposite to the surface on which another layer and / or the reversible thermosensitive recording layer is provided. 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 blocking prevention, curl prevention and antistatic.

The method for forming the reversible thermosensitive recording material of the present invention by laminating each layer in the present invention on a support is not particularly limited, and it can be formed by a conventional method. For example, it is possible to use a smearing device such as an air knife coater, a blade coater, a bar coater, or a curtain coater, and various printing machines such as planographic printing, letterpress, intaglio printing, flexo, gravure, screen, and hot melt. In addition to the usual drying process, UV irradiation / EB
Each layer can be retained by irradiation. By these methods. It is possible to apply and print one layer at a time or multiple layers at the same time.

The reversible thermosensitive recording layer is prepared by mixing each dispersion obtained by finely pulverizing each component, coating on a support and drying, and each solution obtained by dissolving each component in a solvent. It can be obtained by a method of mixing, coating on a support and drying. Drying conditions also differ depending on the dispersion medium or solvent such as water. In addition to this, there is also a method in which the respective components are mixed and heated to melt a fusible component, and coating is performed while hot.

The reversible thermosensitive recording layer and / or the protective layer and / or the intermediate layer include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide and hydroxide. In addition to pigments such as aluminum and urea-formalin resin, zinc stearate, higher fatty acid metal salts such as calcium stearate, paraffin, oxidized paraffin, polyethylene, polyethylene oxide, stearic acid amide, and the like for the purpose of preventing head wear and sticking. Waxes such as castor wax and the like, and also a dispersant such as sodium dioctylsulfosuccinate, a surfactant, a fluorescent dye, an ultraviolet absorber and the like may be contained.

Next, a method of coloring and decoloring the reversible thermosensitive recording material of the present invention will be described. To form a color image, heating may be followed by rapid cooling. For example, a color image can be formed by heating the reversible thermosensitive recording 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, laser light or the like is used for heating for an extremely short time, cooling occurs immediately after the heating is completed, so that a color image can be retained. On the other hand, in order to erase the color image, it is sufficient to cool slowly after heating. For example, a reversible thermosensitive recording material on which a colored image is formed is used as a thermal head, a laser beam, a heat roll, a heat stamp, a high frequency heating,
Remove the heat source because not only the reversible thermosensitive recording layer but also the support will be heated if heated by radiant heat from a hot air, electric heater, light source such as tungsten lamp or halogen lamp, or hot air for a relatively long time. Even so, the cooling speed becomes slow and the color image is erased. Therefore, even if the same heating temperature and / or the same heat source is used, the formation and deletion of the color image can be arbitrarily performed by controlling the cooling rate.

[0072]

Operation: General formulas (1) to (1) used in the present invention
The reason for the improvement in light resistance of the compound represented by (3) is not clear. However, since hydrazine and hydrazine derivatives have a strong reducing action, it is presumed that the compounds represented by the general formulas (1) to (3) also have a similar reducing action, that is, an effect as an antioxidant. In addition, the general formula (1)
The compounds represented by (3) to (3) have a group having a hydrogen bonding ability such as an amide bond in the molecule similarly to the reversible color developer, and thus are incorporated into the reversible color developer and the color-blending mixture. It is presumed that even if added in a small amount, the light resistance is improved, and at the same time, bleeding out to the surface of the reversible thermosensitive recording layer does not occur.

Part of the specific method for synthesizing the compound in the present invention will be explained below, but the present invention is not limited to this.

Synthesis Example 1 Synthesis of Exemplified Compound (5-11). In a flask equipped with a stirrer, a cooler and a calcium chloride drying tube, 5.3 g of 1,1-dimethylhydrazine and 200 ml of tetrahydrofuran (hereinafter, THF) were charged, and 6.7 g of hexamethylene diisocyanate was stirred at room temperature. It was dripped slowly. After the completion of dropping, the mixture was stirred under reflux for 1 hour. After completion of the reaction, the reaction solution was cooled to room temperature and the precipitated crystals were collected by filtration. Recrystallization from acetonitrile gave 8.5 g of the desired product. Melting point 144 [deg.] C.

Synthesis Example 2 Synthesis of Exemplified Compound (5-17). In a flask equipped with a stirrer, a condenser and a calcium chloride drying tube, 6.7 g of N-aminomorpholine and THF2
00 ml was charged, and 5.1 g of hexamethylene diisocyanate was slowly added dropwise while stirring at room temperature. After the completion of dropping, the mixture was stirred under reflux for 1 hour. After completion of the reaction, the reaction solution was cooled to room temperature and the precipitated crystals were collected by filtration. Recrystallization from ethanol gave 7.4 g of the desired product. Melting point 19
5 ° C.

[0076]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention thereto.
Further, the number of parts and percentages in the examples are based on mass.

Example 1 (A) Preparation of reversible heat-sensitive coating liquid 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide as a dye precursor 40 parts, 160 parts of the exemplified compound (8-4) as a reversible developer, 20 parts of the exemplified compound (5-1) as an additive, a vinyl chloride / vinyl acetate copolymer as a binder resin (manufactured by Union Carbide Co., product A reversible heat-sensitive coating liquid was prepared by grinding together with 16 parts of VYHH) and 1600 parts of THF in a paint conditioner for 24 hours.

(B) Coating of reversible heat-sensitive recording layer The reversible heat-sensitive coating solution prepared in (A) was applied to a polyethylene terephthalate (hereinafter PET) sheet, and the solid amount of the coating was 5.
It was coated at 0 g / m ² , dried at 60 ° C. for 24 hours, and then treated with a super calendar to obtain a reversible thermosensitive recording material.

Example 2 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (5) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the procedure (5) was changed.

Example 3 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (5-1) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 1) was performed.

Example 4 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (5-1) were used as additives.
A reversible heat-sensitive recording material was obtained in the same manner as in Example 1 except that the change to 7) was performed.

Example 5 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (5-1) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 9) was performed.

Example 6 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (6-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 1) was performed.

Example 7 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (6) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 2) was performed.

Example 8 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (6-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the procedure (5) was changed.

Example 9 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (6-1) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 1) was performed.

Example 10 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (7-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 1) was performed.

Example 11 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the procedure was repeated except that the exemplified compound (8-4) was changed to the exemplified compound (8-8) as the reversible developer. A reversible thermosensitive recording material was obtained in the same manner as in Example 1.

Example 12 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the reversible developer was changed from Exemplified compound (8-4) to Exemplified compound (8-8), and as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the compound (5-11) was changed from 1).

Example 12 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the reversible developer was changed from Exemplified compound (8-4) to Exemplified compound (8-9) and used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the compound (5-17) was changed from 1).

Example 13 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the reversible developer was changed from Exemplified compound (8-4) to Exemplified compound (8-10) and used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the compound (5-21) was changed from 1).

Example 14 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the reversible developer was changed from Exemplified compound (8-4) to Exemplified compound (8-11), and as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the compound (6-6) was changed from 1).

Example 15 In the preparation of the (A) reversible heat-sensitive coating liquid of Example 1, the reversible developer was changed from the exemplified compound (8-4) to the exemplified compound (8-14), and the reversible developer was used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the compound (7-3) was changed from 1).

The compound used in Comparative Example is shown in Chemical formula 18.

[0095]

[Chemical 18]

Comparative Example 1 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the reversible heat-sensitive composition was prepared in the same manner as in Example 1 except that the exemplified compound (5-1) was not used as an additive. A recording material was obtained.

Comparative Example 2 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 1) was performed.

Comparative Example 3 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the change to 2) was performed.

Comparative Example 4 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible heat-sensitive recording material was obtained in the same manner as in Example 1 except that the change to 3) was performed.

Comparative Example 5 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the procedure (4) was changed.

Comparative Example 6 In the preparation of the reversible heat-sensitive coating liquid (A) of Example 1, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that the procedure (5) was changed.

Example 16 (C) Preparation of reversible heat-sensitive coating liquid 3-diethylamino-6-methyl-7 as a dye precursor
40 parts of anilinofluorane, 160 parts of the exemplified compound (8-3) as a reversible developer, 20 parts of the exemplified compound (5-1) as an additive, vinyl chloride as a binder resin /
A reversible heat-sensitive coating liquid was prepared by grinding with a paint conditioner for 24 hours together with 16 parts of vinyl acetate copolymer (manufactured by Union Carbide Co., trade name VYHH) and 1600 parts of THF.

(D) Coating of reversible heat-sensitive recording layer The reversible heat-sensitive coating solution prepared in (A) was applied to a polyethylene terephthalate (hereinafter PET) sheet, and the amount of solids smeared was 5.
It was coated at 0 g / m ² , dried at 60 ° C. for 24 hours, and then treated with a super calendar to obtain a reversible thermosensitive recording material.

Example 17 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from Exemplified compound (8-3) to Exemplified compound (8-4) and used as an additive. Exemplified product (5-1)
From Example 1 to Example Compound (5-6)
A reversible thermosensitive recording material was obtained in the same manner as in 6.

Example 18 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from Exemplified compound (8-3) to Exemplified compound (8-5) and used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (5-9) was changed from 1).

Example 19 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from Exemplified compound (8-3) to Exemplified compound (8-6) and used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (5-11) was changed from 1).

Example 20 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from Exemplified compound (8-3) to Exemplified compound (8-8), and as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (5-15) was changed from 1).

Example 21 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from the exemplified compound (8-3) to the exemplified compound (8-9), and the reversible developer was used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (5-20) was changed from 1).

Example 22 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from the exemplified compound (8-3) to the exemplified compound (8-10), and the reversible developer was used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (6-1) was changed to the exemplified compound (6-1).

Example 23 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from Exemplified compound (8-3) to Exemplified compound (8-11) and used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (6-2) was changed from 1).

Example 24 In the preparation of the reversible heat-sensitive coating liquid of (C) of Example 16, the reversible developer was changed from Exemplified compound (8-3) to Exemplified compound (8-14) and used as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (6-6) was changed from 1).

Example 25 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the reversible developer was changed from Exemplified compound (8-3) to Exemplified compound (8-16), and as an additive. Exemplified compound (5-
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the compound (6-12) was changed from 1).

Comparative Example 7 Reversible thermosensitive material was prepared in the same manner as in Example 16 except that the exemplified compound (5-1) was not used as an additive in the preparation of the reversible thermosensitive coating solution (C) of Example 16. A recording material was obtained.

Comparative Example 8 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the change to 1) was performed.

Comparative Example 9 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the change to 2) was performed.

Comparative Example 10 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the procedure (3) was changed.

Comparative Example 11 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible thermosensitive recording material was obtained in the same manner as in Example 16 except that the procedure (4) was changed.

Comparative Example 12 In the preparation of the reversible heat-sensitive coating liquid (C) of Example 16, the exemplified compounds (5-1) to (9-) were used as additives.
A reversible heat-sensitive recording material was obtained in the same manner as in Example 16 except that the above procedure was changed to 5).

Test 1 (Lightfastness of Image Area) The reversible thermosensitive recording materials obtained in Examples 1 to 15 and Comparative Examples 1 to 6, Examples 16 to 25 and Comparative Examples 7 to 12 were printed with Kyocera print head KJT. -256-8 MGF1 with Okura Electric Thermal Facsimile Printing Tester TH-PMD was used to print with an applied voltage of 1.1 ms for an applied voltage of 26 V, and the optical density of the resulting colored image was measured with a densitometer Macbeth R.
Each was measured using D918. Next, the obtained color image was irradiated with a fluorescent lamp of 10,000 lux for 100 hours, and the optical density of the color image was measured using a densitometer Macbeth RD918. Then, the color image after light irradiation was erased by heating at 140 ° C. for 1 second using a heat stamp. The optical density of the erased portion was measured using a densitometer Macbeth RD918.

Test 2 (Light resistance of erased portion / background portion) The reversible thermosensitive recording materials obtained in Examples 1-15 and Comparative Examples 1-6, Examples 16-25 and Comparative Examples 7-12 were manufactured by Kyocera. Printing was performed using a thermal facsimile printing tester TH-PMD manufactured by Okura Electric Co., Ltd. with a print head KJT-256-8MGF1 under the condition of an applied pulse of 1.1 milliseconds and an applied voltage of 26 volts. The obtained color image is printed with a heat stamp 140
The sample was erased by heating at ℃ for 1 second to obtain an erased sample. Macbeth R densitometer for the optical density of the erased part and the background of the erased sample
Each was measured using D918. Then, the obtained erased sample was irradiated with a fluorescent lamp of 10,000 lux for 100 hours, and the optical densities of the erased portion and the background portion of the erased sample were measured using a densitometer Macbeth RD918.

Test 3 (Change in Color Density with Time = Image Stability) The reversible thermosensitive recording materials obtained in Examples 1 to 15 and Comparative Examples 1 to 6, Examples 16 to 25 and Comparative Examples 7 to 12 were used as Kyocera. Using Okura Electric's thermosensitive facsimile printing tester TH-PMD with manufactured printing head KJT-256-8MGF1,
Printing was performed under the conditions of an applied voltage of 1.1 msec and an applied voltage of 26 V, and the temperature was 40 ° C. and the relative humidity was 20%.
After storing for a time, using a densitometer Macbeth RD918,
The optical densities of the color-developed part and the background part before and after the test were measured, and the image residual rate was calculated by the following formula 1.

[0122]

## EQU1 ## A = (C / B) × 100 A: Image residual rate (%) B: Color density before test-background density before test C: Color density after test-background density after test

Test 4 (Bleedout of Additive) The reversible thermosensitive recording materials obtained in Examples 1 to 15 and Comparative Examples 1 to 6, Examples 16 to 25 and Comparative Examples 7 to 12 were heated at a temperature of 2.
After storing for 1 week in an atmosphere of 5 ° C and 65% relative humidity,
The surface state of the reversible thermosensitive recording material was visually observed for bleed-out of the additive. In addition, when no bleed-out was observed, it was evaluated as ◯, when slight bleed-out was recognized, it was evaluated as Δ, and when additive was blown on the surface, it was evaluated as x.

Test 1 of Examples 1-15 and Comparative Examples 1-6
The results of ~ 2 are shown in Table 1, and the results of tests 3-4 are shown in Table 2.

[0125]

[Table 1]

[0126]

[Table 2]

The results of tests 1 and 2 of Examples 16 to 25 and comparative examples 7 to 12 are shown in Table 3, and the results of tests 3 to 4 are shown in Table 4.

[0128]

[Table 3]

[0129]

[Table 4]

From Tables 1 to 4, it can be seen that when the compound of the present invention was used as an additive in the reversible thermosensitive recording material, the light resistance was improved regardless of the type of dye precursor. Specifically, the density of the colored image was not significantly reduced, the erasability of the colored image after light irradiation was not deteriorated, and the recoloring of the erased portion and the coloring of the background portion were also small. Furthermore, the erasability and the image stability under high temperature conditions were not affected, and no bleed out of the additive was observed.

[0131]

From the above results, the colorless or light-colored dye precursor on the support and the reversible dye precursor which causes a reversible change in color tone due to the difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording material containing a color developing agent, at least one compound containing two or more groups having an N, N-disubstituted hydrazine structure in the same molecule is contained in the recording material. It was possible to obtain a reversible thermosensitive recording material capable of forming and erasing an image with clear contrast, excellent in light resistance, and capable of holding a stable image over time.

Claims (7)

[Claims] 1. A colorless or light-colored dye precursor on a support, and a reversible developer that causes a reversible color tone change in the dye precursor due to a difference in heating temperature and / or cooling rate after heating. A reversible thermosensitive recording material containing at least one compound having two or more groups having an N, N-disubstituted hydrazine structure in the same molecule in the recording material.
A reversible thermosensitive recording material characterized by containing a seed. 2. A colorless or light-colored dye precursor on a support, and a reversible developer that causes a reversible color change in the dye precursor due to a difference in heating temperature and / or cooling rate after heating. A reversible heat-sensitive recording material containing the following general formula (1), (2) or (3)
A reversible thermosensitive recording material comprising at least one compound represented by: [Chemical 1] (In the formula 1, R ¹ and R ² may be the same or different,
Each represents a hydrocarbon group which may have a substituent,
R ¹ and R ² may be linked to each other to form a ring. X ¹ represents an oxygen atom or a sulfur atom. n is 2-5
Represents the integer. A ¹ represents an n-valent organic residue. The n parenthesized partial structures bonded to A ¹ may be the same or different. ) [Chemical 2] (In Formula 2, R ³ and R ⁴ may be the same or different,
Each represents a hydrocarbon group which may have a substituent,
Further, R ³ and R ⁴ may be linked to each other to form a ring. X ² represents a divalent group containing a hetero atom, but excludes an amide group and a thioamide group. m represents an integer of 2 to 5.
A ² represents an m-valent organic residue. The m parenthesized partial structures bonded to A ² may be the same or different. ) [Chemical 3] (In Formula 3, R ⁵ and R ⁶ may be the same or different,
Each represents a hydrocarbon group which may have a substituent,
R ⁵ and R ⁶ may be linked to each other to form a ring. R ⁷ represents a hydrocarbon group which may have a substituent. X ³ represents an oxygen atom or a sulfur atom. X ⁴ represents a single bond, an oxygen atom, or a sulfur atom. q is 2 or 3
Represents The q parenthesized partial structures bonded to the phosphorus atom may be the same or different. ) 3. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ^{6 of the} compounds represented by the general formulas (1) to (3) are monovalent hydrocarbons having 1 to 8 carbon atoms. The reversible thermosensitive recording material according to claim 2, which is a base. 4. The ring formed by R ¹ and R ² , R ³ and R ⁴ , and R ⁵ and R ⁶ of the compounds represented by the general formulas (1) to (3) each has a substituent. Optionally a piperidine ring,
The reversible thermosensitive recording material according to claim 2, which is either a piperazine ring or a morpholine ring. 5. A divalent group having 1 to 24 carbon atoms, wherein A ¹ and A ² of the compounds represented by the general formulas (1) and (2) may have a substituent and / or a hetero atom. The reversible thermosensitive recording material according to claim 2, which is a trivalent organic residue. 6. A of the compound represented by the general formula (1)
¹ biuret bond, urea bond, isocyanurate bond, or a reversible thermosensitive recording according to claim 2, it is characterized in a divalent or trivalent organic residue comprising through allophanate bond material. 7. The reversible thermosensitive recording material according to claim 1, wherein at least one kind of compounds represented by the following general formula (4) is used as the reversible developer. . [Chemical 4] (In the formula 4, X ⁵ and X ⁶ represent an oxygen atom, a sulfur atom, or a divalent group having a hydrocarbon group-free —CONH— bond at both ends as a minimum constitutional unit. R ⁸ is a single bond or Represents a divalent hydrocarbon group having 1 to 12 carbon atoms, where R ⁹ is 1 carbon atom.
To 18 divalent hydrocarbon groups. R ¹⁰ represents a monovalent hydrocarbon group having 1 to 24 carbon atoms. r represents an integer of 0 to 4, and R ⁹ and X ^{6 which} are repeated when r is 2 or more may be the same or different. )