JPH08252974A - Reversible thermosensitive recording material - Google Patents

Abstract

PURPOSE: To form and erase an image with excellent contrast by using specific compound as electron acceptive compound, and further incorporating at least one of three types of specific compounds as a color erasing accelerator. CONSTITUTION: A compound represented by a formula I is used as electron acceptive compound which creates reversible color tone change due to the difference of cooling velocity after heating at a dye precursor which is normally colorless or pale. Further, at least one type from compounds represented by formulae II, III and IV are incorporated as a color erasing accelerator, where in the formulae I to IV, X is O or S, Y is bivalent group having -COHN bond, A is a complex ring having one or more of N atoms, B is amino compound having one or more of N atoms, R is CH group having several tens to 24 of C, R<a> , R<c> and R<e> are 1-12C CH2 group, R<b> and R<f> are 1-24C CH group, R<d> is 1-24C CH group having one S, n and p are 1 to 3, m is 0 to 3, and h, i, j and k are 0 or 1, of integer respectively. Thus, erasability can be improved.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a support and a heat-sensitive recording layer containing an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting developer as main components. By heating with a thermal head, a heating pen, a laser beam or the like, a dye precursor and a developer react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45-
No. 14039 is disclosed.

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

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

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

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

On the other hand, JP-A-2-188293, JP-A-2-188294, and International Publication No. WO90 /
No. 11898 describes a reversible thermosensitive recording medium composed of a leuco dye and a color-developing and decoloring agent for coloring and decoloring the leuco dye by heating. The color-developing agent is an amphoteric compound having an acidic group for coloring the leuco dye and a basic group for decoloring the colored leuco dye, and the coloring effect by the acidic group or the decoloring effect by the basic group is controlled by controlling thermal energy. One of them is preferentially generated, and coloring and erasing are performed. However, in this method, it is impossible to completely switch the color development reaction and the color removal reaction only by controlling the thermal energy, and since both reactions occur at a certain ratio at the same time, sufficient color development density cannot be obtained, and the color removal Can not be done completely. Therefore, sufficient image contrast cannot be obtained. 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.
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 fatty acid dicarboxylic acids and alkylthiophenols having an alkyl group having 10 or more carbon atoms, alkyloxyphenols, alkylcarbamoylphenols, and gallic acid alkyl esters are exemplified. However, even this recording medium has a low color density, or
The two problems of incomplete decolorization cannot be solved at the same time. Furthermore, in JP-A-5-294063, fatty acids, waxes, higher alcohols, as decolorization accelerators for improving the erasability of the reversible thermosensitive recording medium,
Although various esters of phosphoric acid / benzoic acid / phthalic acid or oxyacid, silicone oils, liquid crystal compounds, surfactants and fatty acid saturated hydrocarbons having 10 or more carbon atoms are disclosed, their effects are still small, so that they have not been disclosed yet. The image density at the time of erasing is high and it cannot be said to be practical. Further, as a decolorization accelerator, JP-A-6-270544 discloses organic amines such as hexylamine and trimethylenediamine, but when added in a small amount, no improvement is observed in the decolorization temperature range, and image storage It only worsens sex. When adding a large amount,
Coloring is poor and the image storability deteriorates, and it is very difficult to define the allowable range of the addition amount.

Generally, when a reversible thermosensitive material is colored, a means such as a thermal head, a laser beam, a hot pen or the like may be used so that rapid cooling is followed by heating, and when decoloring, slow cooling after heating. Radiation heat from a light source such as a thermal head, a heat roll, a heat stamp, high frequency heating, hot air, an electric heater and a tungsten lamp, a halogen lamp, etc.
Had to use some special erasing device.

Further, in Japanese Patent Laid-Open No. 6-155905,
Higher alcohols, higher esters and higher amides are disclosed as decoloring agents that can be changed to a decolored state without heating, but the color development is poor and the erasing concentration is not sufficient.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems associated with erasing a printed image and to form and erase an image with good contrast. It is to provide a recording material. As the erasing method in the present invention, it is possible to use a relatively simple method such as a method of leaving it in a natural environment without heating, and a method of heating with a dryer etc. which is an essential item in daily life. Is.

[0011]

DISCLOSURE OF THE INVENTION The inventors of the present invention have used an electron-accepting compound which causes a reversible change in color tone of a dye precursor which is usually colorless or light-colored and a cooling rate after heating. In a reversible thermosensitive recording material containing the following, as a result of extensive studies to improve its erasability, a compound represented by the following general formula I was used as the electron-accepting compound, and further represented by the following general formulas II, III and IV. It has been found, surprisingly, that the inclusion of at least one of the compounds indicated results in a reversible thermosensitive recording material in which the image erasure can be carried out completely and uniformly in the low temperature region of or close to the natural environment. The present invention has been completed.

[0012]

Embedded image (In the general formula I, n represents an integer of 1 to 3, m represents an integer of 0 to 3, X represents an oxygen or sulfur atom, k represents 0 or 1, and R represents 10 to 24 carbon atoms. Represents a hydrocarbon group.)

[0013]

[Chemical 6] (In the general formula II, A represents a heterocycle having at least one nitrogen atom. Ra represents ^a divalent hydrocarbon group having 1 to 12 carbon atoms. Y represents at least one -CONH- bond. R ^b represents a hydrocarbon group having 1 to 24 carbon atoms, and h represents 0 or 1.)

[0014]

[Chemical 7] (In the general formula III, B represents an amino compound having at least one nitrogen atom. R ^c represents a divalent hydrocarbon group having 1 to 12 carbon atoms. Y represents a group defined in the general formula II. . R ^d is .i from 1 carbon atoms with one or more sulfur atom represents a hydrocarbon group of 24 represents 0 or 1.)

[0015]

Embedded image (In the general formula IV, R ^e represents a divalent hydrocarbon group having 1 to 12 carbon atoms, and R ^f represents a hydrocarbon group having 1 to 24 carbon atoms.
p represents an integer of 1 to 3, and j represents 0 or 1. )

Specific examples of the electron-accepting compound represented by the above general formula I, which is used in the present invention and causes a reversible color change in the usually colorless to light-colored electron-donating dye precursor, are as follows. However, the present invention is not limited to this.

N-Tetradecylsuccinic acid [N- (4-hydroxyphenyl)] imide, n-hexadecylsuccinic acid [N- (4-hydroxyphenyl)] imide, n-octadecylsuccinic acid [N- (4- Hydroxyphenyl)] imide, n-dococenylsuccinic acid [N- (4-hydroxyphenyl)] imide, (n-octadecyloxy) succinic acid [N- (4-hydroxyphenyl)] imide, (n-tetradecylthio) succin Acid [N- (4-hydroxyphenyl)] imide, (n-octadecylthio) succinic acid [N- (4-hydroxyphenyl)] imide, [(n-octadecylthio)] methylsuccinic acid [N
-(4-hydroxyphenyl)] imide, [2- (n-
Hexadecylthio) ethyl] succinic acid [N- (4-hydroxyphenyl)] imide, [3- (n-dodecyloxy) propyl] succinic acid [N- (4-hydroxyphenyl)] imide and the like.

As described in Japanese Patent Application No. 6-293281, the electron-accepting compound used in the present invention can be extremely easily synthesized from various readily available raw materials by various synthetic routes.

The electron-accepting compound according to the present invention may be used alone or in admixture of two or more kinds. Usually, the amount of the electron-accepting compound according to the present invention to the colorless or light-colored dye precursor is 5 or less. ˜5000 wt%, preferably 10-3000 wt%.

In the compound represented by the above general formula II, A is a heterocycle having one or more nitrogen atoms, but the nitrogen atom-containing compound is 5
And preferably a 6-membered ring, specifically, as a 5-membered ring, a pyrrolidine ring, an imidazolidine ring, a thiazolidine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, a thiazole ring, or the like, a 6-membered ring, a piperidine ring, Examples thereof include a morpholine ring, a thiomorpholine ring, a piperazine ring, a pyridine ring and a pyrimidine ring, and the nitrogen atom in the ring may be either directly bonded to R ^a or not bonded. Further, the above heterocycle is a lower alkyl group, an aralkyl group,
It may be substituted with an aryl group or a hydroxyl group. Further, R ^a is specifically ^a divalent hydrocarbon group having 1 to 12 carbon atoms, preferably an alkylene group, and may contain an aromatic ring in the group. It may be. Y represents a divalent group having at least one —CONH— bond, and specific examples thereof include amide (—CONH—, —NHCO—), urethane (—NHC).
OO-, -OCONH-), urea (-NHCONH)
-), Diacylamine (-CONHCO-), diacylhydrazide (-CONHNHCO-), oxalic acid diamide (-NHCOCONH-), acylurea (-CONH)
CONH-, -NHCONHCO-), 3-acylcarbazide acid ester (-CONHNHCOO-), semicarbazide (-NHCONHNH-, -NHNHCONH)
-), Acyl semicarbazide (-CONHNHCONH
-, - NHCONHNHCO-), diacyl aminomethane (-CONHCH ₂ NHCO -), 1- acylamino-1- Ureidometan (-CONHCH ₂ NHCONH
-, -NHCONHCH ₂ NHCO-), it includes groups such as malonamide (-NHCOCH ₂ CONH-).

Specific examples of the compound represented by the general formula II include the following compounds described in Japanese Patent Application No. 6-272796, but the present invention is not limited thereto.

First, as an example in which A is a nitrogen-containing 5-membered heterocycle, N- (1-pyrrolidinyl) -tetradecane amide, octadecyl N- (1-pyrrolidinyl) carbamate, and N-octadecylcarbamic acid [2- ( 1-pyrrolidinyl) ethyl], N- [3- (1-pyrrolidinyl) propiono] -N′-tetradecanohydrazide, N-octadecylcarbamic acid [3- (3-methylimidazolidinyl) propyl], N-octadecyl -3- (3-thiazolidinyl) propanamide, 1- [6- (1-pyrrolyl) hexanoyl] -4-tetradecyl semicarbazide, N- [2- (4-imidazolyl) ethyl] -N'-
Octadecyl oxamide, 1- [3- (1-imidazolyl) propionylamino] -1-tetradecanoylaminomethane, N- [11- (1-pyrazolyl) undecanoyl] -N′-octadecylurea and the like can be mentioned.

As an example of A being a nitrogen-containing 6-membered heterocycle, hexadecyl N-piperidinocarbamate, N
-(2-piperidinoethyl) octadecanamide, N-
Octadecylcarbamic acid (2-piperidinoethyl),
Hexadecyl N- (2-piperidinoethyl) carbamate, N- (3-piperidinopropiono) -N'-octadedecanohydrazide, 1- (3-piperidinopropionyl) -3-octadecylsemicarbazide, N- ( 11-
Piperidinoundecano) -N'-decanohydrazide, N
-[2- (1-Methyl) piperidinyl] carbo-N'-
Octadecanohydrazide, N- [4- (1-benzyl)
Hexadecyl piperidino] carbamate, N- [2-
(4-Hydroxypiperidino) ethyl] carbamate hexadecyl, N-morpholinocarbamate hexadecyl, N- (3-morpholinopropyl) octadecane amide, N-octadecylcarbamic acid (2-morpholinoethyl), N- (2-morpholino) Hexadecyl ethyl) carbamate, hexadecyl N- (3-morpholinopropyl) carbamate, N- (3-morpholinopropiono)
-N'-octadecanohydrazide, N- (3-morpholinopropiono) -N'-docosanohydrazide, N- (3
-Morpholinopropyl) -N'-octadecyloxamide, 1- (3-morpholinopropionyl) -4-octadecyl semicarbazide, hexadecyl 3- (6-morpholinohexanoyl) carbazide, N- [p- (morpholinomethyl) benzo] -N'-octadecanohydrazide, N- (p-piperidinophenyl) carbamate hexadecyl, N- (p-morpholinophenyl) -N'-octadecyloxamide, N- (11-morpholinoundecano) -N ′ -Decanohydrazide, N- (11-morpholinoundecano) -N′-octadecanohydrazide, N
-Octadecylcarbamic acid (2-thiomorpholinoethyl), N- (3-thiomorpholinopropiono) -N'-
Octadecanohydrazide, 1- (11-thiomorpholinoundecanyl) -4-decylsemicarbazide, N- (4
-Methylpiperazinyl) hexadecyl carbamate, N
-(4-methylpiperazinyl) -N'-octadecyl oxamide, N- [2- (4-methylpiperazinyl) ethyl] -N'-octadecyl oxamide, 1- [3- (4
-Methylpiperazinyl) propionylamino] -1-octadecanoylaminomethane, N- [2- (1,4-dimethyl) piperazinyl] carbo-N'-octadecanohydrazide, 1-octadecanoyl-4- [2- (4-benzylpiperazinyl) ethyl] semicarbazide, N-
[2- (4-phenylpiperazinyl) ethyl] -N'-
Octadecyl malondiamide, N- (2-pyridyl) carbamate hexadecyl, N- (2-pyridyl) -N '
-Dodecyloxamide, 1- (4-pyridinecarbonylamino) -1- (N'-octadecylureido) methane and the like can be mentioned, but the present invention is not limited thereto.

In the compound represented by the general formula III, B is an amino compound having one or more nitrogen atoms, preferably a tertiary amino group-containing compound, and more preferably 5
And a compound containing a 6-atom ring-forming tertiary amino group. The nitrogen atom in the ring may or may not be directly bonded to R ^c, and the amino compound may be substituted with a lower alkyl group having a hydroxyl group, an aralkyl group, an aryl group or the like. Further, R ^c is specifically a divalent hydrocarbon group having 1 to 12 carbon atoms, preferably an alkylene group, which may contain an aromatic ring, or further, an aromatic ring alone. It may be. Y has the same meaning as defined in the general formula II.

Specific examples of the compound represented by the above general formula III include the following compounds described in Japanese Patent Application No. 7-27864. First, as an example of B being an acyclic amino compound, N- (3-diethylaminopropyl) -11-decylthioundecane amide, N
-(3-Diethylaminopropyl) carbamic acid-11
-Dodecylthioundecyl, N- (2-octadecylthioethyl) carbamic acid-6-diethylaminohexyl, N-6-dimethylaminocapro-N'-3-dodecylthiopropionohydrazide, 10- (dodecylthio) decylcarbamide Acid-6-dicyclohexylaminocapryl, 1- (3-diethylaminopropiono) -4
-(10-decylthiodecyl) semicarbazide, N-4
-Aminocyclohexyl-N'-10-decylthiodecyloxamide, 1- (3-dimethylaminopropionylamino) -1- (11-dodecylthiodecanoylamino) methane, N-3-diethylaminopropyl-N'-
10-dodecyl thiodecyl urea etc. are mentioned.

As an example in which B is a cyclic amino compound, N- (2-dodecylthio) ethylcarbamic acid-
2- (1-pyrrolidinyl) ethyl, N-3-pyrrolidinylpropiono-N'-11-decylthioundecanohydrazide, N-5-1H-tetrazolyl-N'-10-decylthiodecylurea, N- 2-thiazolyl-N'-1
0-dodecylthiodecyloxamide, 1- (11-dodecylthioundecano) -4- (2-thiazolinyl) semicarbazide, N-piperidinocarbamic acid-6-octadecylthiohexyl, N- [2- (1- Piperidino) ethyl] -11-cyclohexylthioundecane amide,
N- (10-decylthiodecyl) carbamic acid-2-
(1-Piperidino) ethyl, N- [3- (1-piperidino) propiono] -N'-3-dodecylthiopropionohydrazide, 1- [3- (1-piperidino) propiono] -4- (10-decylthiodecyl ) Semicarbazide, N- [11- (1-piperidino) undecano]-
N'-3-dodecylthiopropionohydrazide, N-
(4-piperidinyl) carbo-N'-11-dodecylthioundecanohydrazide, 1- [4- (1-methyl) piperidinylcarbo] -4- (10-dodecylthiodecyl) semicarbazide, N- [2- (4-hydroxy-1
-Piperidinyl) ethyl] -11-dodecylthioundecane amide, N- (2-morpholinoethyl) -11-decylthioundecane amide, N- (10-dodecylthiodecyl) carbamic acid-6-morpholinohexyl, N-
2-Morpholinoethyl 2-decylthiodecylcarbamate, N-11-Morpholinoundecano-N'-3-
Cyclohexylthiopropionohydrazide, N-3-morpholinopropyl-N'-10-decylthiodecyloxamide, N-11-dodecylthioundecyloxycarbo-N'-3-morpholinopropionohydrazide, N-
(3-morpholinopropyl) -3-dodecylthiopropanamide, N- (4-methylpiperazinyl) -3-dodecylthiopropanamide, 1- (3-morpholinopropionylamino) -1- (11-decylthio Propionylamino) methane, N-2-morpholinoethyl-N'-
10-decyl thiodecyl malondiamide etc. are mentioned.

In the compound represented by the above general formula IV, p is 1
It represents an integer of 3 to 3, but is preferably a compound in which p is 1 or 2, that is, a 5- and 6-atom ring-forming compound.
R ^e is specifically a divalent hydrocarbon group having 1 to 12 carbon atoms, but preferably represents an alkylene group, and may contain an aromatic ring, or further, it may be an aromatic ring only. Good. j represents the presence or absence of a sulfur atom.

Specific examples of the compound represented by the above general formula IV include the following compounds described in Japanese Patent Application No. 7-27865.

First, as an example of a compound in which j is 0,
N-tetradecyl succinimide, N-hexadecyl succinimide, octadecyl succinimide, N-docosyl succinimide, N-dodecyl glutarimide, N
-(4-heptylphenyl) glutarimide, N-tetradecylglutarimide, N-hexadecylglutarimide, N-octadecylglutarimide, N-docosylglutarimide, N-dodecyladipinimide, N-octadecyladipinimide, etc. Can be mentioned.

Further, as an example in which j is a compound,
N- (2-decylthio) ethylsuccinimide, N-
(2-dodecylthio) ethylsuccinimide, N- (2
-Octadecylthio) ethylsuccinimide, N- (3
-Decylthio) propylsuccinimide, N- (3-dodecylthio) propylsuccinimide, N- (3-octadecylthio) propylsuccinimide, N- (5-octylthio) pentylsuccinimide, N- (5-decylthio) pentylsuccinimide, N- ( 5-dodecylthio) pentylsuccinimide, N- (5-octadecylthio) pentylsuccinimide, N- (10-octylthio) decylsuccinimide, N- (10-decylthio) decylsuccinimide, N- (10-dodecylthio) decylsuccinimide, N- (10-Octadecylthio) decylsuccinimide, N- (4-dodecylthio) phenylsuccinimide, N- (4-dodecylthio) phenylsuccinimide, N- (4-octadecylthio) phenylsuccinine Bromide, N-(2-cyclohexyl-thio) ethyl succinimide, N-(3- cyclohexyl-thio) propyl succinimide, N-(5-cyclohexyl thio) pentyl succinimide, N-(10
-Cyclohexylthio) decylsuccinimide, N-
(4-cyclohexylthio) phenyl succinimide,
N- (2-decylthio) ethylglutarimide, N-
(2-dodecylthio) ethylglutarimide, N- (2
-Octadecylthio) ethylglutarimide, N- (3
-Decylthio) propylglutarimide, N- (3-dodecylthio) propylglutarimide, N- (octadecylthio) propylglutarimide, N- (5-octylthio) pentylglutarimide, N- (5-decylthio) pentylglutarimide, N- (5-dodecylthio) pentylglutarimide, N- (5-octadecylthio) pentylglutarimide, N- (10-octylthio) decylglutarimide, N- (10-decylthio) decylglutarimide, N- (10- Dodecylthio) decylglutarimide, N- (10-octadecylthio) decylglutarimide, N- (4-dodecylthio) phenylglutarimide, N- (4-dodecylthio) phenylglutarimide, N- (4-octadecylthio) phenylglutarimide Imi , N-(2-cyclohexyl-thio) ethyl glutarimide, N-(3- cyclohexyl-thio) propyl glutarimide, N-(5-cyclohexyl thio) pentyl Ruguru barrel imide, N-(10
-Cyclohexylthio) decylglutarimide, N-
(4-cyclohexylthio) phenylglutarimide,
N- (2-decylthio) ethyl adipinimide, N-
(2-dodecylthio) ethyl adipinimide, N- (2
-Octadecylthio) ethyl adipinimide, N- (3
-Decylthio) propyladipinimide, N- (3-dodecylthio) propyladipinimide, N- (octadecylthio) propyladipinimide, N- (5-octylthio) pentyladipinimide, N- (5-decylthio) pentyladipinimide, N- (5-dodecylthio) pentyladipinimide, N- (5-octadecylthio) pentyladipinimide, N- (10-octylthio) decyladipinimide, N- (10-decylthio) decyladipineimide, N- (10- Dodecylthio) decyladipinimide, N- (10-octadecylthio) decyladipinimide, N- (4-dodecylthio) phenyladipinimide, N- (4-dodecylthio) phenyladipinimide, N- (4-octadecylthio) phenyladipine Imi , N-(2-cyclohexyl-thio) ethyl adipate imide, N-(3- cyclohexyl-thio) propyl adipic imide, N-(5-cyclohexyl thio) pentyl adipic imide, N-(10
-Cyclohexylthio) decyl adipinimide, N-
(4-cyclohexylthio) phenyladipinimide and the like can be mentioned.

The compounds of the general formulas II, III and IV are each 1
One kind or a mixture of two or more kinds may be used. Usually, the preferable amount used is 0.5% by weight or more and 10% by weight based on the dye precursor.
00% or less, more preferably 1% by weight or more and 200
% Or less, but considering the contrast of coloring and erasing,
Most preferably, it is 5% by weight or more and 100% or less.

On the other hand, the usually colorless to light-colored electron-donating dye precursor used in the present invention is represented by those generally used for pressure-sensitive recording paper and heat-sensitive recording paper, 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) fluorane,

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

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

As a specific example of the method for producing the reversible thermosensitive recording material of the present invention, a colorless or light-colored dye precursor and the electron-accepting compound according to the present invention are mainly contained, and a decoloring accelerator is added as an additional component. And a method of forming a reversible thermosensitive recording layer by coating or printing these on a support.

As a method for preparing a coating solution for incorporating the dye precursor, the reversible color developer and the decolorization accelerator according to the present invention into the reversible thermosensitive recording layer, each compound is dissolved in a solvent or dispersed in a dispersion medium. Dispersion in, then mixed, each compound is dissolved in a solvent or dispersed in a dispersion medium, each compound is dissolved by heating and homogenized and then cooled, dissolved in a solvent or dispersed in a dispersion medium However, the method 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.

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

A heat-fusible substance may be contained in the reversible thermosensitive recording layer as an additive for controlling the color developing sensitivity and the decoloring temperature of the reversible thermosensitive recording layer. 60 ° C
Those having a melting point of ~ 200 ° C are preferable, and especially 80 ° C.
Those having a melting point of ˜180 ° C. are preferred. It is also possible to use a sensitizer which is used in general thermal recording paper. For example, waxes such as N-hydroxymethylstearic acid amide, behenic acid amide, stearic acid amide, and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, p-benzylbiphenyl,
Biphenyl derivatives such as 4-allyloxybiphenyl,
1,2-bis (3-methylphenoxy) ethane, 2,
Polyether compounds such as 2'-bis (4-methoxyphenoxy) diethyl ether, 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 of them may be used 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 resins such as polyethylene and polypropylene, 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 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 constitution of the reversible thermosensitive recording material of the present invention is as follows:
Only the reversible thermosensitive recording layer may be used. If necessary,
A protective layer may be provided on the reversible thermosensitive recording layer, or an intermediate layer may be provided between the reversible thermosensitive recording layer and the support. 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, information can be recorded electrically, magnetically, or optically in the reversible thermosensitive recording layer and / or on the surface provided with another layer and / or the reversible thermosensitive recording layer and / or on the opposite surface. The material may be included. Also, curling is prevented on the surface opposite to the surface on which the reversible thermosensitive recording layer is provided,
A back coat layer may be provided for the purpose of 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 /
Each layer can be held by EB irradiation.

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. Aluminum, pigments such as urea-formalin resin, and other higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearamide, and castor wax, A dispersant such as sodium dioctylsulfosuccinate, a surfactant, a fluorescent dye and the like can be added.

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. A heating temperature of 40 ° C. or lower is sufficient, and it can be erased even with a simple device used in daily life such as a dryer, but it can be completely erased by leaving it in a natural environment without heating. The erasing speed can be freely controlled by the type of additive, the amount of additive compounded, and the heating temperature.

The principle of image formation and erasure of the heat-sensitive recording material of the present invention is not clear yet, but it is considered as follows. When a colorless or light-colored dye precursor is heated together with an electron-accepting compound such as a phenolic compound, electron transfer from the dye precursor to the electron-accepting compound occurs to develop a color.
At this time, it is considered that the electron-accepting compound molecule exists in the extremely close vicinity of the dye molecule that has developed color. Further, when the electron-accepting compound molecule is separated from the color-developed dye molecule, the color-developed dye molecule receives the electron again and becomes in the state of the dye precursor before color development. It is considered that the present invention changes the distance between the molecule of the electron-accepting compound and the molecule of the dye by heating to perform coloring and decoloring.

More specifically, since the electron-accepting compound according to the present invention has a large fatty chain in its structure, the electron-accepting compound has low compatibility with the dye precursor molecule and the colored dye molecule, and in the coagulated state. It is considered that they are hardly compatible with each other. Further, in a state where the dye precursor molecule and the electron-accepting compound molecule according to the present invention can freely move like a heating and melting state, the dye precursor molecule and the electron-accepting compound molecule according to the present invention are mixed with each other at a certain ratio to form a color. It becomes a state. Therefore, when the colored mixture in the molten state is slowly cooled, the electron-accepting compound according to the present invention and the dye molecule become insoluble in each other and phase-separate and disappear when the temperature is lowered. At this time, since the electron-accepting compound used in the present invention has a weak hydrogen-bonding ability in the molecule, the color-developed state is very unstable, and it is considered that the dye and the developer are easily separated. On the other hand, when the material is rapidly cooled, it solidifies before phase separation, that is, in the colored state, so that the colored state is fixed and the colored state is stably maintained even after the solidification.

The above-mentioned general formula II used in the present invention,
The decolorization-accelerating compounds represented by III and IV have a bond having a hydrogen bonding ability such as a fatty chain and an amide bond in the molecule like the above reversible developer, so that the coloring state is destroyed by heating and the reversibility is reversible. It is believed that the developer acts as a nucleus for crystallization when it separates from the dye. On the other hand, generally, it is widely known that a heat-sensitive recording material using an electron-donating dye precursor erases a printed image by contact with a basic compound such as amine. That is, since the decolorization accelerator used in the present invention also has a nitrogen-containing heterocycle having a decoloring action in the molecule, it is possible to reduce the temperature of the electron-donating dye precursor and the electron-accepting reversible developer after cooling. It is considered that the decolorization phenomenon is accelerated during the phase separation.

[0053]

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

Example 1 (A) Preparation of reversible heat-sensitive coating liquid 40 parts of a dye precursor, 3-di-n-butylamino-6-methyl-7-anilinofluorane, was added to a 2.5% polyvinyl alcohol aqueous solution. It was pulverized together with 90 parts by a paint conditioner for 18 hours to obtain a dye precursor dispersion liquid (liquid A). Then (n-octadecylthio) succinic acid [N-
(4-hydroxyphenyl)] imide 100 parts 1.2
The mixture was pulverized with 400 parts of a 5% aqueous solution of polyvinyl alcohol for 18 hours with a paint conditioner to obtain an electron acceptor compound dispersion liquid (liquid B). Furthermore, magnesium carbonate 20
And 47 parts of a 0.2% aqueous polyvinyl alcohol solution were pulverized with a homogenizer to obtain a dispersion liquid (C liquid). Also, N
-(3-morpholinopropyl) carbamate hexadecyl 1.0 part was added with 1.25% polyvinyl alcohol aqueous solution 40
The resulting mixture was pulverized with a paint conditioner for 18 hours together to obtain a decolorization accelerator dispersion (liquid D). After mixing these four kinds of dispersion liquids of liquids A, B, C and D, 170 parts of 10% polyvinyl alcohol aqueous solution and 350 parts of water were added and mixed well to prepare a reversible heat-sensitive coating liquid.

The reversible heat-sensitive coating solution prepared in (A) was applied to a polyethylene terephthalate (PET) sheet so that the solid content amount was 4 g / m ² , dried and then treated with a super calendar to apply the reversible heat-sensitive coating. A recording material was obtained.

Example 2 The same as Example 1 except that hexadecyl N- (4-methylpiperazinyl) carbamate was used instead of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1. A reversible thermosensitive recording material was obtained.

Example 3 Example 1 was repeated except that N-octadecylcarbamate [2- (1-pyrrolidinyl) ethyl] was used instead of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1. A reversible thermosensitive recording material was obtained in the same manner as.

Example 4 In place of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1, N- (2-morpholinoethyl) -11-decylthioundecane amide was used. A reversible thermosensitive material was obtained in the same manner as in 1.

Example 5 In place of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1, N- (3-diethylaminopropyl) -11-decylthioundecane amide was used. A reversible thermosensitive material was obtained in the same manner as in 1.

Example 6 In place of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1, N- (4-methylpiperazinyl) -3-dodecylthiopropanamide was used, except that A reversible thermosensitive material was obtained in the same manner as in Example 1.

Example 7 A reversible thermosensitive material was obtained in the same manner as in Example 1 except that N-octadecylsuccinimide was used instead of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1. .

Example 8 Example 8 was repeated except that N- (2-octadecylthio) ethylsuccinimide was used instead of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1. A reversible thermosensitive material was obtained.

Example 9 Instead of the (n-octadecylthio) succinic acid [N- (4-hydroxyphenyl)] imide used in Example 1, [(n-octadecylthio)] methylsuccinic acid [N
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that-(4-hydroxyphenyl)] imide was used.

Example 10 Instead of 3-di-n-butylamino-6-methyl-7-anilinofluorane used in Example 1, 3-diethylamino-6-methyl-7-anilinofluorane was used. A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that it was used.

Comparative Example 1 The procedure of Example 1 was repeated, except that hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1 was omitted.

Comparative Example 2 The procedure of Example 1 was repeated except that stearic acid amide was used in place of hexadecyl N- (3-morpholinopropyl) carbamate used in Example 1.

Comparative Example 3 Instead of the (n-octadecylthio) succinic acid [N- (4-hydroxyphenyl)] imide used in Example 1, [(n-octadecylthio)] methylsuccinic acid [N
-(4-hydroxyphenyl)] imide, N-
A reversible thermosensitive recording material was obtained in the same manner as in Example 1 except that hexadecyl (3-morpholinopropyl) carbamate was removed.

Test 1 (coloring density = thermoresponsiveness) The thermal recording materials obtained in Examples 1 to 10 and Comparative Examples 1 to 3 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 applied under the condition of an applied voltage of 26 V for an applied pulse of 1.1 milliseconds, and the density of the obtained color image was measured using a densitometer Macbeth RD918. The results are shown in Table 1.

Test 2 (Image erasing speed at room temperature) The heat-sensitive recording materials obtained in Examples 1 to 10 and Comparative Examples 1 to 3 were printed by the method of Test 1, and the obtained color image part was printed at room temperature (23 C.) and the change in the density of the color image with time every 1 hour was measured in the same manner as in Test 1. Table 1 shows the time when the optical density of the color image was below 0.15.

Test 3 (image erasability at room temperature) In Test 2, the optical density of the decolored portion when the image was erased most was measured in the same manner as in Test 1. The results are shown in Table 1.

Test 4 (Image erasing speed at 35 ° C.) The thermal recording materials obtained in Examples 1 to 10 and Comparative Examples 1 to 3 were printed by the method of Test 1, and the color image portion obtained was 35.
The sample was allowed to stand at 0 ° C., and the change with time of the density of the color image was measured every 10 minutes in the same manner as in Test 1. The optical density of the color image is 0.15
Table 1 shows the time when it was lower than.

Test 5 (Image erasability at 35 ° C.) In Test 4, the optical density of the decolored part at the time of best erasure was measured in the same manner as in Test 1. The results are shown in Table 1.

Test 6 (Image erasability with a dryer) The printed image obtained in Test 1 was heated with a dryer, and the optical density of the most erased decolored portion was measured in the same manner as in Test 1. The results are shown in Table 1.

[0074]

[Table 1]

[0075]

As shown in Table 1, a colorless or light-colored dye precursor is usually provided on a support, and an electron acceptor which causes a reversible color change in the dye precursor due to a difference in cooling rate after heating. In a reversible thermosensitive recording material containing a photosensitive compound, an electron-accepting compound represented by the general formula I,
By combining the compound represented by the general formula II, III or IV as the decoloring accelerator, by a simple method such as leaving in a natural environment or at a relatively low temperature, or heating with a dryer etc. Erasable,
It was possible to obtain a reversible thermosensitive recording material having extremely high practicality.

Claims (1)

[Claims] 1. A reversible thermosensitive recording material comprising a colorless or light-colored dye precursor and an electron-accepting compound which causes the dye precursor to undergo reversible color tone change due to a difference in cooling rate after heating. A reversible sensation characterized by using a compound represented by the following general formula I as the electron-accepting compound and further containing at least one compound represented by the following general formulas II, III and IV as an erasing accelerator. Thermal recording material. Embedded image (In the general formula I, n represents an integer of 1 to 3, m represents an integer of 0 to 3, X represents an oxygen or sulfur atom, k represents 0 or 1, and R represents 10 to 24 carbon atoms. Represents a hydrocarbon group of). (In the general formula II, A represents a heterocycle having at least one nitrogen atom. Ra represents ^a divalent hydrocarbon group having 1 to 12 carbon atoms. Y represents at least one -CONH- bond. Represents a divalent group having R ^b represents a hydrocarbon group having 1 to 24 carbon atoms, and h represents 0 or 1.) (In the general formula III, B represents an amino compound having at least one nitrogen atom. R ^c represents a divalent hydrocarbon group having 1 to 12 carbon atoms. Y represents a group defined in the general formula II. R ^d is 1 to 24 carbon atoms having at least one sulfur atom
Represents a hydrocarbon group of. i represents 0 or 1. ) [Chemical 4] (In the general formula IV, R ^e represents a divalent hydrocarbon group having 1 to 12 carbon atoms, and R ^f represents a hydrocarbon group having 1 to 24 carbon atoms.
p represents an integer of 1 to 3, and j represents 0 or 1. )