JPH09290563A - Reversible heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the lower image density at decolorization than ever, the scarce portion left uneliminated and the uniform elimination at the elmination temperature lower than ever and over the temperature range wider than even by a method wherein at least one kind of the specified decolorization accelerators is added. SOLUTION: By adding at least one kind of decolorization accelerators represented by formulae I, II, III or IV to reversible heat-sensitive recording material forming on a support and containing normal colorless or light-colored dye precursor and reversible developer, which develops reversible color tone change in the dye precursor by changing the cooling speed after heating, the reversible heat-sensitive recording material, by which the elimination of an image can be fully and uniformly carried out over wide temperature range. In this case, A<1> represents monovalent substituent having two or more oxygen atoms, A<2> and A<3> represent respectively a divalent substituent having two or more oxygen atoms, R represents 10-24C hydrocarbon group, X<a> represents divalent group having at least one or more amide linkage and X<b> represents a trivalent group having at least one or more amide linkage.

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 A heat-sensitive recording material generally comprises a support provided with a heat-sensitive recording layer containing an electron-donating, usually colorless or pale-colored dye precursor and an electron-accepting developer as main components. By heating with a thermal head, a heating pen, a laser beam or the like, the dye precursor and the developer react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45-
It is disclosed in, for example, Japanese Patent Publication No. 14039.

In general, the above-mentioned type of heat-sensitive recording material cannot erase the part once the image is 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 unformed part. For this reason, when the area of the heat-sensitive recording portion is limited, there has been a problem that the recordable information is limited and all necessary information cannot be recorded.

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 forming portion and the image non-forming portion 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 decolorizing the colored leuco dye, and has a coloring effect by an acidic group or a decolorizing effect by a basic group by controlling thermal energy. One is preferentially generated to perform color development and decoloration. 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 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. But,
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 is not satisfactory in practice. Furthermore, JP-A-5-294
No. 063, fatty acids, waxes, higher alcohols, various esters of phosphoric acid / benzoic acid / phthalic acid or oxyacids, silicone oils, as decoloring accelerators for improving the erasability of the reversible thermosensitive recording medium. Liquid crystal compound,
Although a surfactant and a fatty acid saturated hydrocarbon having 10 or more carbon atoms are disclosed, the effect thereof is small, and therefore the image density at the time of erasing is still high and it cannot be said to be practical.

As described above, according to the conventional technique, a practical reversible image having a clear image contrast, capable of forming a high-density image and completely erasing, and capable of holding a stable image with time in an environment of daily life. The production of the thermosensitive recording material has been difficult. On the other hand, as already described in Japanese Patent Application Laid-Open No. 6-210954, the present applicants have proposed that a colorless or pale-colored electron-donating dye precursor can be reversibly changed in color tone by heating, that is, an electron-accepting material which causes color development and decoloration. Compound (reversible developer)
However, in order to obtain a practically better image quality and an easy-to-use recording medium, there is room for improvement in the image density at the time of erasing, the erasing start temperature, the erasing temperature range, and the like. was there.

[0009]

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. That is. More specifically, the invention provides a reversible thermosensitive recording material which has a lower image density during erasing, less erasing residue, and can be erased uniformly at a lower temperature and in a wider temperature range. This is an issue.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention cause a reversible change in color tone of a dye precursor, which is usually colorless or light-colored, on a support and a difference in cooling rate after heating. In a reversible thermosensitive recording material containing a reversible developer, as a result of diligent studies to further improve its erasability, the result is represented by the following general formula (1), (2), (3) or (4). It was found that a reversible thermosensitive recording material capable of completely and uniformly erasing an image in a wide temperature range can be obtained by adding at least one kind of a specific decolorization accelerator, and the present invention has been completed. It was

[0011]

[Chemical 6]

[0012]

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[0013]

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[0014]

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In equations (1), (2), (3) and (4),
A ¹ represents a monovalent substituent having two or more oxygen atoms, and A ² and A ³ represent divalent substituents having two or more oxygen atoms. R
Represents a hydrocarbon group having 10 to 24 carbon atoms, which may contain a sulfur atom. X ^a is an amide bond (-CONH
-) Represents a divalent group having at least one or more, and ^Xb represents a trivalent group having at least one amide bond (-CONH-).

On the other hand, the reversible color developer used in the present invention is not particularly limited, and examples thereof include JP-A-2-188293, JP-A-2-188294 and International Publication No. W.
O90 / 11898 and the color-developing / reducing agent described in JP-A-5-
A reversible developer such as an organic phosphonic acid, a carboxylic acid or a phenolic compound described in JP124360 can be used, but those represented by the following general formula (5) are particularly preferable in terms of color density and decoloring property. . In addition, the following general formula (5)
Compounds outside these ranges can be preferably used in the present invention as long as they have the same characteristics as the compound of (1).

[0017]

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In the equation (5), n is an integer of 1 to 3, i, j
And k each represent 0 or 1. However, when i is 1,
j indicates 1. R ¹ and R ² represent a divalent hydrocarbon group having 1 to 18 carbon atoms, and R ³ represents a hydrocarbon group having 1 to 24 carbon atoms. X ¹ represents a divalent group having at least one —CONH— bond, and X ² represents a divalent group having at least one —CONH— bond, an oxygen atom or a sulfur atom.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In the compound of the decolorization accelerator represented by the general formula (1), (2), (3) or (4), A ¹ is a monovalent group having two or more oxygen atoms, A ² and A ³ represent a divalent substituent having two or more oxygen atoms, and a specific example thereof represents a polyether compound residue. Further, in the general formula (4), A ² and A ³ may be the same or different. X
^a represents a divalent group having at least one —CONH— bond, and specific examples thereof include amide (—CO
NH-), urea (-NHCONH-), urethane (-O)
CONH-), acyl hydrazide (-CONHNH
-), Oxalic acid diamide (-NHCOCONH-), acylurea (-CONHCONH-), carbazic acid ester (-OCONHNH-), semicarbazide (-NH)
CONHNH-), 1-acyl semicarbazide (-CO
NHNHCONH -), 1- acylamino-1- Ureidometan (-CONHCH ₂ NHCONH-), it includes groups such as malonamide (-NHCOCH ₂ CONH-). Similarly, X ^b represents a trivalent group having at least one —CONH— bond, and specific examples thereof include one hydrogen atom in the substituent of X ^a as a covalent bond. It can be expressed as changed.

Specific examples of the compound represented by the general formula (1), (2), (3) or (4) include the following compounds, but the present invention is not limited thereto.

First, examples of the compound represented by the general formula (1) include N-dodecyl-3,6,9-trioxadecane amide and N-octadecylcarbamic acid (3,6,9).
-Trioxadecane), N-octadecanoyl-N'-
(3,6,9,12-Tetraoxatridecanoyl) hydrazide, N-hexadecyl-N '-(4,7-dioxanonyl) oxamide, N-octadecyl-N'-
(4,7,10-Trioxaundecyl) urea, 1-tetradecyl-4- (4,7,10,13-tetraoxaheptadecyl) semicarbazide, 1- (dodecanoylamino) -1- (3,6 , 9-trioxatetradecanoylamino) methane, N- (11-decylthiodecanoyl) -N '-(3,6,9,12-tetraoxatridecanoyl) hydrazide,

Examples of the compound represented by the general formula (2) include N, N'-ditetradecanoyl-4,7,10-trioxatridecane-1,13-diamine and N, N'-.
Dioctadecanoyl-4,7,10-trioxatridecane-1,13-diamine, N, N'-dioctadecanoyl-4,9-dioxadodecane-1,12-diamine, 1,12- Bis [2-octadecanoylhydrazino) carbonyl] -2,5,8,11-tetraoxadodecane, 1,13-bis (2-octadecanoylureylene) -4,7,10-trioxatridecane , 1,1
3-bis (N'-dodecyloxamide) -4,7,10
-Trioxatridecane, N, N'-bis (11-decylthiodecanoyl) -4,9-dioxadodecane-1,
12-diamine, 3,9-bis (1,1-dimethyl-2
-Octadecylaminocarbonyloxyethyl) -2,
4,8,10-Tetraoxaspiro [5,5] undecane, 3,9-bis [3- (2-octadecylureylene) propyl] -2,4,8,10-tetraoxaspiro [5,5] Undecane,

Examples of the compound represented by the general formula (3) include N-dodecylaminocarbonyl-4-aza-1,
7,10,13-tetraoxacyclopentadecane, N
-Octadecylaminocarbonyl-4-aza-1,7,
10,13-Tetraoxacyclopentadecane, N-
(2-Octadecylureylene) -4-aza-1,7,
10,13-Tetraoxacyclopentadecane, N-decylaminocarbonylcarbonyl-4-aza-1,7,
10,13-Tetraoxacyclopentadecane, N-
(3-dodecylmercaptopropionyl) -4-aza-
1,7,10,13-tetraoxacyclopentadecane, N-octadecylaminocarbonyl-4-aza-
1,7,10,13,16-pentaoxacyclooctadecane, N- (N'-octadecyloxamide) -4-
Aza-1,7,10,13,16-pentaoxacyclooctadecane,

Examples of the compound represented by the general formula (4) include N, N'-bis (octadecylaminocarbonyl).
-1,13-diaza-1,7,10,16-tetraoxacyclooctadecane, N, N'-bis (N'-dodecyloxamide) -1,13-diaza-1,7,10,1
6-Tetraoxacyclooctadecane, N, N'-bis (tetradecylaminocarbonylmethylcarbonyl)-
1,13-diaza-1,7,10,16-tetraoxacyclooctadecane, N, N'-bis (N'-tetradecylureido) -1,13-diaza-1,7,10,1
Examples thereof include 6-tetraoxacyclooctadecane.

The amount of the compound represented by the general formula (1), (2), (3) or (4) is preferably 0.5% by weight or more and 1000% by weight or less based on the dye precursor, more preferably Is 1% by weight or more and 200% by weight or less. Further, in consideration of the heat-resistant storage stability of the printed image, the content is most preferably 5% by weight or more and 100% by weight or less.

Next, as the reversible color developer used in the present invention, compounds outside these ranges can be used in the present invention as long as they have the same characteristics as the compound of the general formula (5).
The method for synthesizing the reversible color developer represented by the general formula (5) is described in JP-A-6-210954, Japanese Patent Application No. 5-160547, Japanese Patent Application No. 5-256825, and Japanese Patent Application No. 5-256825. It is described in Japanese Patent Application No. 5-317555, Japanese Patent Application No. 5-328101 and Japanese Patent Application No. 6-10310.

In the compound represented by the above general formula (5), R
¹ and R ² are divalent hydrocarbon groups having 1 to 18 carbon atoms, but may contain an aromatic ring in the group or may be only an aromatic ring. Specific examples of the divalent group having at least one —CONH— bond represented by X ¹ and X ² include amide (—CONH—, —NHCO—), urea (—NHCO).
NH-), urethane (-NHCOO-, -OCONH
-), Diacylamine (-CONHCO-), diacylhydrazide (-CONHNHCO-), oxalic acid diamide (-NHCOCONH-), acylurea (-CONH)
CONH-, -NHCONHCO-), 3-acylcarbazide ester (-CONHNHCOO-), semicarbazide (-NHCONHNH-, -NHNHCONH)
-), Acyl semicarbazide (-CONHNHCONH
-, - NHCONHNHCO-), diacyl aminomethane (-CONHCH ₂ NHCO -), 1- acylamino-1- Ureidometan (-CONHCH ₂ NHCONH
-, - NHCONHCH ₂ NHCO-), a group such as malonamide (-NHCOCH ₂ CONH-).

The compound represented by the general formula (5) is an electron-accepting compound, and has a specific decoloring effect, that is, a reversible effect, although it has the ability to color the leuco dye. It should be noted that the electron-accepting compounds used in ordinary thermal recording materials, that is, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, benzyl 4-hydroxybenzoate, etc. No reversible effect is seen. Specific examples of the electron-accepting compound represented by the general formula (5) are shown below, but the invention is not limited thereto.

For example, in equation (5), i = 0 / j = 0 / k
Examples of the compound of = 0 include 4'-hydroxyhexadecaneanilide, N-octadecyl-4-hydroxybenzamide, N- (4-hydroxyphenyl) -N'-octadecylurea, N- (4-hydroxybenzo) -N '.
-Octadecanohydrazide, N- (3,4-dihydroxyphenyl-N'-octadecyloxamide and the like.

In the formula (5), compounds having i = 0 / j = 1 / k = 0 include N- [2- (4-hydroxyphenyl) ethyl] -N'-octadecylurea and N- [3 −
(4-Hydroxyphenyl) propiono] -N'-octadecanohydrazide, N- [3- (4-hydroxyphenyl) propiono] -N'-docosanohydrazide, 1-
[3- (4-hydroxyphenyl) propionyl] amino-1-octadecanoylaminomethane, 1- (4-hydroxyphenylacetyl) -4-octadecyl semicarbazide and the like.

In the formula (5), compounds having i = 1 / j = 1 / k = 0 include N-hexadecyl- (4-hydroxyphenylthio) acetamide and N- [2- (4-hydroxyphenylthio). ) Ethyl] -N'-octadecyl urea, N- (4-hydroxyphenylthio) aceto-N '
-Docosanohydrazide, N- [11- (4-hydroxyphenylthio) undecano] -N'-decanohydrazide, N- [2- (4-hydroxyphenylthio) ethyl] -N'-octadecyloxamide, N -[4- (4
-Hydroxyphenylthio) phenyl] -N'-octadecyloxamide, N- [4- (4-hydroxyphenylthiomethyl) benzo] -N'-docosanohydrazide and the like.

In the formula (5), a compound in which i = 0 / j = 0 / k = 1 is N- (4-hydroxyphenyl)-
3-dodecylthiopropanamide, N- (4-hydroxyphenyl) -N'-3-octadecylthiopropylurea, 4-hydroxy-4'-octadecyloxybenzanilide, 4-hydroxy-4'-dodecylthiobenzanilide, 2- (4-octadecanoylaminophenyl) -4'-hydroxyacetanilide, 2- [4-
(N'-octadecyl ureido) phenyl] -4'-hydroxyacetanilide and the like.

In the formula (5), the compound in which i = 0 / j = 1 / k = 1 is N- [3- (4-hydroxyphenyl) propiono] -N '-(3-dodecylthiopropiono). ) Hydrazide, N- [3- (3,4-dihydroxyphenyl) propiono] -N '-(11-decylthioundecano) hydrazide and the like.

In the formula (5), a compound in which i = 1 / j = 1 / k = 1 is N- [3- (4-hydroxyphenylthio) propiono] -N '-(3-octadecylthiopropion Ono) hydrazide, N- [11- (3,4,5-
Trihydroxyphenylthio) undecano] -N'-
(11-octadecyl thioundecano) hydrazide and the like.

These reversible developers may be used either individually or in combination of two or more. The amount of the reversible developer based on the dye precursor is 5 to 5000% by weight, preferably It is 10 to 3000% by weight.

The usually colorless or light-colored electron-donating dye precursor used in the present invention is represented by a known compound 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) 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-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3 -Diethylamino-7
-(2-chloroanilino) fluoran,

3-Diethylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl- 7-anilinofluoran, 3-
(N-ethyl-N-tolyl) amino-6-methyl-7-
Phenethylfluoran, 3-diethylamino-7- (4
-Nitroanilino) fluoran, 3-dibutylamino-
6-methyl-7-anilinofluoran, 3- (N-methyl-N-propyl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6 Methyl-7-anilinofluoran, 3- (N-
Methyl-N-cyclohexyl) amino-6-methyl-7
-Anilinofluorane, 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluorane and the like.

(4) Thiazine compounds Benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene 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 usually colorless to light-colored dye precursors may be used either individually or in combination of two or more.

Specific examples of the method for producing the reversible thermosensitive recording material of the present invention include a dye precursor and a reversible developer as main components, and a compound according to the present invention as an additive component on a support. And a method of forming a reversible heat-sensitive recording layer by coating the above.

As a method for preparing a coating solution for incorporating the dye precursor, the reversible developer and the compound according to the present invention into the reversible thermosensitive recording layer, each compound is dissolved in a solvent or dispersed in a dispersion medium. After that, a method of mixing each compound and then dissolving in a solvent or dispersing in a dispersion medium, a method of dissolving each compound by heating and homogenizing and then cooling, and dissolving in a solvent or dispersing in a dispersion medium, etc. Is not specified. At the time of dispersion, a dispersant may be used if necessary. When water is the dispersion medium, examples of the dispersant include water-soluble polymers such as polyvinyl alcohol and various surfactants. 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.

A binder may be added 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, such as latex of polyvinylidene chloride and the like but not limited thereto.

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 preferred, and those having a melting point of 80 ° C to 180 ° C are particularly preferred. A sensitizer used in general thermosensitive recording paper can also be used. Examples of these compounds include waxes such as N-hydroxymethylstearic acid amide, behenic acid amide, stearic acid amide, and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, p-benzylbiphenyl, and the like.
Biphenyl derivatives such as 4-allyloxybiphenyl,
1,2-bis (3-methylphenoxy) ethane, 2,
Polyether compounds such as 2'-bis (4-methoxyphenoxy) diethyl ether and bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate,
Carbonic acid such as oxalic acid bis (p-methylbenzyl) ester or an oxalic acid diester derivative may be mentioned, and two or more kinds thereof may be added in combination.

The support used in the reversible thermosensitive recording material of the present invention includes paper, various non-woven fabrics, woven fabrics, synthetic resin films such as polyethylene terephthalate and polypropylene, paper laminated with synthetic resins such as polyethylene and polypropylene, and synthetic. Paper, metal foil, glass, etc., or a composite sheet in which these are combined can be arbitrarily used according to the purpose, but the invention is not limited to these, and these may be opaque, translucent or transparent. Good. In order to make the background appear white or another specific color, a white pigment, a colored dye or a bubble may be contained in or on the support. 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 one or more of water-soluble polymer, white or colored dye / 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 two or three or more layers. 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 preventing blocking, curling and charging.

The method for forming the reversible thermosensitive recording material of the present invention by laminating each layer of the present invention on a support is not particularly limited, and the conventional method can be used. 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 and
Each layer can be held by EB irradiation.

The reversible thermosensitive recording layer is prepared by mixing the respective dispersions obtained by finely pulverizing the respective components, coating and drying on a support, and the respective solutions obtained by dissolving the respective components in a solvent. It can be obtained by a method of mixing, coating on a support and drying. Drying conditions vary depending on a dispersion medium or solvent such as water. In addition, there is a method in which the components are mixed and heated to melt a fusible component, and the mixture is heated and applied.

Further, 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 may also be contained in addition to a dispersant such as sodium dioctylsulfosuccinate, a surfactant, and a fluorescent dye.

Next, a method of coloring and decoloring the reversible thermosensitive recording material of the present invention will be described. In order to develop a color, rapid cooling may occur after heating, and for example, heating with a thermal head, laser light or the like is possible. or,
It can be decolored by slow cooling after heating, and it can be performed by using, for example, a thermal head, a heat roll, a heat stamp, high frequency heating, hot air, radiant heat from a light source such as an electric heater and a tungsten lamp or a halogen lamp.

Part of the specific method for producing the decolorization accelerator of the present invention will be illustrated below, but the present invention is not limited thereto.

Synthesis Example 1 Synthesis of N-octadecylcarbamic acid (3,6,9-trioxadecane). In a flask equipped with a stirrer, a condenser and a calcium chloride drying tube, 10.0 g of triethylene glycol monomethyl ether, 1.5 g of triethylamine and 100 ml of dimethylacetamide were charged, and 15.0 g of octadecyl isocyanate was slowly added with stirring. After the dropping was completed, the mixture was heated and stirred at 60 ° C. for 2 hours. The reaction solution was cooled to room temperature, poured into water, and the precipitated crystals were collected by filtration under reduced pressure. The crystals were washed with distilled water and then recrystallized from 2-propanol to obtain 6.5 g of the desired product. Melting point 8
1 ° C.

Synthesis Example 2 Synthesis of N-octadecanoyl-N '-(3,6,9,12-tetraoxatridecanoyl) hydrazide. In a flask equipped with a stirrer, a condenser and a calcium chloride drying tube, 8.0 g of 3,6,9,12-tetraoxatridecanoylhydrazide, 3.4 g of triethylamine and 100 ml of dimethylacetamide were charged, and stearic acid was added with stirring. 9.4 g of chloride was added slowly. After the dropping was completed, the mixture was heated and stirred at 60 ° C. for 2 hours. The reaction solution was cooled to room temperature, poured into water, and the precipitated crystals were collected by filtration under reduced pressure. The crystals were washed with distilled water and then recrystallized from 2-propanol to obtain 5.3 g of the desired product. Melting point 85 [deg.] C.

Synthesis Example 3 Synthesis of N, N'-ditetradecanoyl-4,7,10-trioxatridecane-1,13-diamine. A flask equipped with a stirrer, a condenser and a calcium chloride drying tube was charged with 5.3 g of diethylene glycol bis (3-aminopropyl) ether, 5.8 g of triethylamine and 80 ml of dimethylacetamide, and with stirring, 13.0 g of myristic acid chloride. Was slowly added. After the dropping was completed, the mixture was heated and stirred at 60 ° C. for 1 hour. The reaction solution was cooled to room temperature, poured into water, and the precipitated crystals were collected by filtration under reduced pressure. The crystals were washed with distilled water and then recrystallized from methanol to obtain 12.2 g of the desired product. Melting point 10
1 ° C.

Synthesis Example 4 N-octadecylaminocarbonyl-4-aza-1,
Synthesis of 7,10,13-tetraoxacyclopentadecane. A flask equipped with a stirrer, a condenser and a calcium chloride drying tube was charged with 2.0 g of 4-aza-1,7,10,13-tetraoxacyclopentadecane and 60 ml of methyl ethyl ketone, and 2.7 g of octadecyl isocyanate was stirred. Was slowly added. After completion of dropping, the mixture was heated under reflux for 2 hours. The reaction solution was cooled to room temperature, poured into water, and the precipitated crystals were collected by filtration under reduced pressure. After washing the crystals with distilled water, recrystallization from 2-propanol,
2.6 g of the target product was obtained. Melting point 66 [deg.] C.

[0059]

The present invention will be described in more detail with reference to the following examples. Parts and percentages in the examples are on a weight basis.

Example 1 (A) Preparation of reversible heat-sensitive coating liquid 40 parts of 3-diethylamino-6-methyl-7-anilinofluorane was added to a 2.5% polyvinyl alcohol aqueous solution 90
The resulting mixture was pulverized with a paint conditioner to obtain a dye precursor dispersion (Solution A). Then, 100 parts of N- (4-hydroxyphenyl) -N'-octadecyl urea was added to 1.
Pulverized with a paint conditioner together with 400 parts of a 25% aqueous solution of polyvinyl alcohol to obtain a reversible developer dispersion (B
Liquid). Furthermore, 20 parts of magnesium carbonate and 0.2%
47 parts of an aqueous polyvinyl alcohol solution was similarly ground (solution C). In addition, N-octadecylcarbamic acid (3,
10 parts of 6,9-trioxadecane) was pulverized together with 40 parts of an aqueous 1.25% polyvinyl alcohol solution with a paint conditioner to obtain a discoloration accelerator dispersion (liquid D). After mixing these four dispersions of liquids A, B, C and D, 1
170 parts of 0% polyvinyl alcohol aqueous solution and 350 parts of water were added and mixed well to prepare a reversible heat-sensitive coating liquid.

(B) Preparation of reversible heat-sensitive recording material The reversible heat-sensitive coating liquid prepared in (A) was applied onto a polyethylene terephthalate (PET) sheet to give a solid content of 2.6 g /
After being smeared and dried so as to have m ² , a 5% aqueous solution of polyvinyl alcohol was smeared and dried thereon so as to have a solid content of 2 g / m ^2, and treated with a super calender to obtain a reversible thermosensitive recording material.

Example 2 N-octadecylcarbamic acid (3, used in Example 1
6,9-trioxadecane) was replaced by N, N′-ditetradecanoyl-4,7,10-trioxatridecane-1,13-diamine in the same manner as in Example 1. A reversible thermosensitive recording material was obtained.

Comparative Example 1 N-octadecylcarbamic acid (3, used in Example 1
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that 6,9-trioxadecane) was removed.

Comparative Example 2 The N-octadecylcarbamic acid (3, 3, used in Example 1
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that 2-benzyloxynaphthalene was used instead of 6,9-trioxadecane).

Test 1 (Color density = Thermal response) The thermal recording materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were applied to a thermal facsimile printing tester manufactured by Okura Electric Co. with a print head KJT-256-8MGF1 manufactured by Kyocera. TH-PMD
Was printed under the conditions of an applied pulse of 1.1 millisecond and an applied voltage of 26 volts, and the density of the obtained color image was measured using a densitometer Macbeth RD918.

Test 2 (Image erasability) The heat-sensitive recording materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were used as a thermal facsimile printing tester TH-manufactured by Okura Electric Co. with a print head KJT-256-8MGF1 manufactured by Kyocera. PMD
Was applied under the conditions of an applied pulse of 1.1 millisecond and an applied voltage of 26 volts, and this was heated at 100 ° C. for 1 second using a heat stamp, and the concentration was measured in the same manner as in Test 1.

Test 3 (Decolorization start temperature) The thermal recording materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were used as a thermal facsimile printing tester TH-manufactured by Okura Electric Co. with a print head KJT-256-8MGF1 manufactured by Kyocera. PMD
After printing for 1.1 milliseconds and applying an applied voltage of 26 volts, using a hot stamp, heat the sample from 60 ° C to 150 ° C at 10 ° C intervals for a total of 10 locations for 1 second each, then test Each concentration was measured in the same manner as in Example 1. The heating temperature at which the optical density of the printed image was lower than 0.15 was defined as the decolorization start temperature.

Test 4 (Change in color density over time = image stability) The thermal recording materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were heat-sensitive facsimiles manufactured by Okura Electric Co. with a print head KJT-256-8MGF1 manufactured by Kyocera. Printing tester TH-PMD
After printing under the conditions of an applied pulse of 1.1 milliseconds and an applied voltage of 26 volts, and stored for 24 hours in an atmosphere of a temperature of 35 ° C. and a relative humidity of 20%, the same procedure as in Test 1 was carried out. The density was measured, and the image residual ratio was calculated by the following equation (1).

[0069]

A = (C / B) × 100 A: Image residual ratio (%) B: Image density before test C: Image density after test

Tests 1 of Examples 1 and 2 and Comparative Examples 1 and 2
The results of No. 4 are shown in Table 1.

[0071]

[Table 1]

Example 3 (C) Preparation of reversible heat-sensitive coating liquid 40 parts of 3-diethylamino-6-methyl-7-anilinofluorane was added to a 2.5% aqueous polyvinyl alcohol solution 90%.
The resulting mixture was pulverized with a paint conditioner to obtain a dye precursor dispersion (Solution A). Next, 200 parts of N- [3- (4-hydroxyphenyl) propiono] -N'-docosanohydrazide were pulverized with a paint conditioner together with 800 parts of a 1.25% aqueous solution of polyvinyl alcohol to obtain a reversible developer dispersion (liquid B). ) Got. Also, N-octadecylcarbamic acid (3,6,9-trioxadecane) 10
Parts were pulverized together with 62 parts of a 1.25% polyvinyl alcohol aqueous solution with a paint conditioner to obtain a decolorization accelerator dispersion (C liquid). After mixing the three kinds of dispersion liquids A, B and C, a 10% aqueous solution of polyvinyl alcohol 26
0 part and 160 parts of water were added and mixed well to prepare a reversible heat-sensitive coating liquid.

(D) Preparation of reversible heat-sensitive recording material The reversible heat-sensitive coating liquid prepared in (C) was applied to a polyethylene terephthalate (PET) sheet to give a solid coating amount of 2.6 g /
After being smeared and dried so as to have m ² , a 5% aqueous solution of polyvinyl alcohol was smeared and dried thereon so as to have a solid content of 2 g / m ^2, and treated with a super calender to obtain a reversible thermosensitive recording material.

Example 4 N-octadecylcarbamic acid (3, 3 used in Example 3
Reversible in the same manner as in Example 3 except that N-octadecanoyl-N '-(3,6,9,12-tetraoxatridecanoyl) hydrazide was used instead of 6,9-trioxadecane). A heat-sensitive recording material was obtained.

Example 5 N-octadecylcarbamic acid (3, 3, used in Example 3
6,9-trioxadecane) was replaced by N, N′-ditetradecanoyl-4,7,10-trioxatridecane-1,13-diamine, but in the same manner as in Example 3. A reversible thermosensitive recording material was obtained.

Example 6 N-octadecylcarbamic acid (3, used in Example 3
N, N'-Dioctadecanoyl-4,7,10-trioxatridecane-1,13-diamine was used instead of (6,9-trioxadecane) in the same manner as in Example 3. A reversible thermosensitive recording material was obtained.

Example 7 N-octadecylcarbamic acid (3, 3 used in Example 3
6,9-trioxadecane) instead of N-octadecylaminocarbonyl-4-aza-1,7,10,13-
A reversible thermosensitive recording material was obtained in the same manner as in Example 3 except that tetraoxacyclopentadecane was used.

Example 8 N-octadecylcarbamic acid (3, used in Example 3
Example 3 except that N, N'-bis (octadecylaminocarbonyl) -1,13-diaza-1,7,10,16-tetraoxacyclooctadecane was used instead of 6,9-trioxadecane). A reversible thermosensitive recording material was obtained in the same manner as.

Comparative Example 3 N-octadecylcarbamic acid (3, 3 used in Example 3
A reversible thermosensitive recording material was obtained in the same manner as in Example 3 except that 6,9-trioxadecane) was removed.

Comparative Example 4 The N-octadecylcarbamic acid (3, 3, used in Example 3
A reversible thermosensitive recording material was obtained in the same manner as in Example 3 except that 2-benzyloxynaphthalene was used instead of (6,9-trioxadecane).

Test 5 (coloring density = thermoresponsiveness) The thermal recording materials obtained in Examples 3 to 8 and Comparative Examples 3 and 4 were used in a thermal facsimile printing tester TH-PMD manufactured by Okura Electric Co., Ltd. equipped with a TDK printing head LH4409. An applied pulse of 1.2 ms was used to print under an applied voltage of 18.7 V, and the density of the obtained color image was measured with a densitometer Macbeth RD91.
8 was used for measurement.

Test 6 (Image erasability) The heat-sensitive recording materials obtained in Examples 3 to 8 and Comparative Examples 3 and 4 were subjected to a thermosensitive facsimile printing tester TH-PMD manufactured by Okura Electric Co., Ltd. with a print head LH4409 manufactured by TDK. Printing was performed with an applied pulse of 1.2 milliseconds for an applied voltage of 18.7 volts, and this was heated at 100 ° C. for 1 second using a heat stamp, and then the density was measured in the same manner as in Test 5.

Test 7 (Decoloring start temperature) The heat-sensitive recording materials obtained in Examples 3 to 8 and Comparative Examples 3 and 4 were subjected to a thermosensitive facsimile printing tester TH-PMD manufactured by Okura Electric Co., Ltd. equipped with a print head LH4409 manufactured by TDK. Printing was performed under the condition of an applied voltage of 18.7 volts with an applied pulse of 1.2 milliseconds, and this was heated from 60 ° C. to 150 ° C. at 10 ° C. intervals at a total of 10 positions for 1 second each using a heat stamp, and then tested. Each concentration was measured in the same manner as in. The heating temperature at which the optical density of the printed image was lower than 0.15 was defined as the decolorization start temperature.

Test 8 (Change in color density over time = image stability) The thermal recording materials obtained in Examples 3 to 8 and Comparative Examples 3 and 4 were used in a thermal facsimile printing tester TH manufactured by Okura Electric Co. with a print head LH4409 manufactured by TDK. -Print using PMD with an applied voltage of 1.2 milliseconds for an applied voltage of 18.7 volts, store in an atmosphere of a temperature of 50 ° C and a relative humidity of 20% for 24 hours, and then, in the same manner as in Test 5, The density of the color-developed portion was measured, and the image residual rate was calculated by the above-mentioned equation 1.

Tests 5 of Examples 3 to 8 and Comparative Examples 3 and 4
The results of No. 8 are shown in Table 2.

[0086]

[Table 2]

[0087]

As shown in Tables 1 and 2, a colorless or light-colored dye precursor and a reversible developer which causes reversible color change in the dye precursor upon heating are contained. In the reversible thermosensitive recording material, the general formula (1) to
By containing the compound represented by (4), a reversible thermosensitive recording material capable of forming and erasing an image with clear contrast and capable of holding a stable image over time in an environment of daily life is obtained. I was able to.

Claims (2)

[Claims] 1. A reversible method comprising a dye precursor which is usually colorless or light-colored on a support and a reversible developer which causes the dye precursor to undergo reversible color tone change due to a difference in cooling rate after heating. A reversible thermosensitive recording material, characterized in that the thermosensitive recording material contains at least one compound represented by the following general formula (1), (2), (3) or (4) as a decolorization accelerator. . Embedded image Embedded image Embedded image Embedded image (In the formulas (1), (2), (3) and (4), A ¹ is a monovalent substituent having two or more oxygen atoms, and A ² and A ³ are divalent substituents having two or more oxygen atoms. Represents a valent substituent, R is 1 carbon atom
It represents a hydrocarbon group of 0 to 24, and may contain a sulfur atom. Xa is ^a divalent group having at least one amide bond (-CONH-), and ^Xb is an amide bond (-C).
ONH-) represents a trivalent group having at least one or more. ) 2. The reversible thermosensitive recording material according to claim 1, wherein the reversible developer is a compound represented by the following general formula (5). Embedded image (In the formula (5), n is an integer of 1 to 3, and i, j and k each represent 0 or 1. However, when i is 1, j represents 1. R ¹ and R ² are the number of carbon atoms. 1 to 18 divalent hydrocarbon group, R ³ represents a hydrocarbon group having 1 to 24 carbon atoms, X ¹ represents a divalent group having at least one —CONH— bond, and X ² represents —. Represents a divalent group having at least one CONH-bond, an oxygen atom or a sulfur atom.)