JPH08142516A - Multicolor thermal recording material - Google Patents

Abstract

(57) [Summary] [Object] To provide a multicolor heat-sensitive recording material which is excellent in color density of an image having a hue obtained with the lowest printing energy and excellent in image storability. [Structure] In a multi-color heat-sensitive recording material having two or more heat-sensitive recording layers each of which develops a different hue, and under which at least one heat-sensitive recording layer is obtained to obtain a multi-color image of two or more colors depending on the difference in printing energy. A multicolor heat-sensitive recording material having a decoloring layer containing a decoloring agent represented by the following general formula 1. Embedded image (However, R represents a cycloalkyl group. Z represents 1 carbon atom.
Represents an alkyl group having 20 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a halogen atom. n represents an integer of 1 to 5. When the substituent Z contains a carbon-carbon single bond, an oxygen atom may be inserted between them. Also, the substituent Z
When contains an alkyl chain, part of it may be an unsaturated bond. When n is 2 or more, 2 or more Zs may be the same or different from each other. However, the compound of Chemical formula 1 has one or less halogen atoms. )

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is the first color (hue obtained with the lowest printing energy) in a multicolor heat-sensitive recording material for obtaining a multicolor image of two or more colors depending on the difference in printing energy.
The present invention relates to a multicolor heat-sensitive recording material excellent in color density and image storability.

[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 compound (developing agent) 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 an image. JP-B-43-4160 and JP-B-45-1.
No. 4039 is disclosed. Such thermal recording materials have the advantages that images can be obtained with a relatively simple device, maintenance is easy, and noise is not generated.Measurement recorders, facsimiles, printers, computer terminals, labels, etc. , Is used in a wide range of fields such as ticket vending machines. When the heat-sensitive recording material is applied to these uses, it is more convenient if a multicolor image of two or more colors can be obtained.

Therefore, many techniques have been proposed for developing the thermosensitive recording material into a multicolor thermosensitive recording material capable of developing two or more colors. The simplest one is a low temperature color thermosensitive recording layer,
It is composed of two layers, that is, a high temperature color thermosensitive recording layer. In printing with low energy, only the low-temperature color-developing layer is colored, and an image of the first hue is obtained. When printing with higher energy, the high-temperature color-developing layer having a hue different from this also develops color, and due to the color mixture of both layers, an image of the second hue different from that of printing with low energy is obtained. As an example of the proposal,
JP-B-49-69, JP-B-49-4342, JP-B-49-27708, JP-A-48-86
No. 543, JP-A-49-65239 and the like are mentioned. However, in this method, although various hues such as red and blue can be selected as the hue of the first color, the selection of the second color is narrowed because the second color is mixed with the first color. After all, it is mainly black that can be introduced into the second color. Further, when a multicolor heat-sensitive recording material of three or more colors is produced by this method, the contrast between the respective hues of colors formed becomes poor and it cannot be put to practical use.

From the above, in order to broaden the selection range of hues to be developed in the multicolor thermosensitive recording material and to achieve multicolor of three or more colors, a system in which the thermosensitive recording layer once developed is decolored is necessary. For example, in the case of a two-color multicolor thermosensitive recording material, 2
When the color-developed image of the color is obtained, if the color-developed image of the first color in that portion is erased, various inconveniences in the case of simply obtaining the two colors can be solved. In particular, the contrast between the first color and the second color is improved, and the range of selecting the hue of the second color is widened.

Next, a specific example of the prior art for obtaining a multicolor heat-sensitive recording material by utilizing the erasing system will be described.
A typical example is a method using a decoloring agent. Specific examples thereof include Japanese Examined Patent Publication No. 50-17865 and Japanese Examined Patent Publication No. 50.
-17866 publication, Japanese Patent Publication No. 50-17867 publication,
Japanese Patent Publication No. 50-17868, Japanese Patent Publication No. 51-1999
No. 1, Japanese Patent Publication No. 51-29024, Japanese Patent Publication No. 51
-87542, JP-A-50-18048,
JP-B-55-36519, JP-A-55-2530
No. 6, JP-A-55-25306, JP-A-55.
-27217, JP-A-55-113593, JP-A-55-139290, and JP-A-55-1.
52094, JP 56-40588, JP 61-120792, and JP 61-1692.
77 and Japanese Patent Publication No. 6-51423. Examples of the decolorizing agent listed therein are higher aliphatic alcohols, polyethers, polyethylene glycols, amides, nitriles, amines and the like. However, when these decoloring agents were used, the color density was lowered and the image storability was seriously deteriorated, so that they could not be put to practical use. These defects were particularly remarkable in the first color.

In addition, the introduction of a fixing system can be mentioned as a conventional technique for obtaining a multicolor heat-sensitive recording material. Specific examples thereof include JP-A-5-142691, JP-A-5-142692, JP-A-5-142693, JP-A-5-169801, and JP-A-5-169.
No. 803 publication and the like. However, since the fixing system requires a fixing process such as exposure, it causes inconvenience such as complication of a recording device and time required to obtain an image.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multicolor thermosensitive recording material which can obtain a multicolor image of two or more colors depending on the difference in printing energy, and which is excellent in the color density of the first color and the image storability. To obtain a thermosensitive recording material.

[0008]

At least one thermosensitive recording material having two or more thermosensitive recording layers each of which develops a different hue, and a multicolor image of two or more colors depending on the difference in printing energy, is obtained. By providing an erasing layer containing the erasing agent represented by the general formula 1 below the heat-sensitive recording layer, it is possible to obtain a multicolor heat-sensitive recording material excellent in the color density of the first color and the image storability. done.

In the chemical formula 1, R represents a cycloalkyl group. Z is an alkyl group having 1 to 20 carbon atoms and 3 to 2 carbon atoms.
It represents a cycloalkyl group having 0, an aralkyl group having 7 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a halogen atom. n represents an integer of 1 to 5. When the substituent Z contains a carbon-carbon single bond, an oxygen atom may be inserted between them. Moreover, when the substituent Z contains an alkyl chain, a part thereof may be an unsaturated bond. When n is 2 or more, 2
The above Zs may be the same or different from each other. However,
The compound of Chemical formula 1 has one or less halogen atoms.

The decolorizing agent according to the present invention is a guanidine derivative having a specific substituent on the 2-phenyl group. As a decolorizer having a structure similar to this, Japanese Patent Publication No. 6-5142 has already been used.
A guanidine derivative having an unsubstituted 2-position phenyl group, which is exemplified in Japanese Patent No. 3, is known. However, use of the derivative causes deterioration of image storability.

Next, specific examples of the compound represented by Chemical formula 1 as the decoloring agent will be listed. 1,3-dicyclohexyl-2
-(2-methylphenyl) guanidine, 1,3-dicyclohexyl-2- (3-methylphenyl) guanidine,
1,3-dicyclohexyl-2- (4-methylphenyl) guanidine, 1,3-dicyclohexyl-2- (2
-Ethylphenyl) guanidine, 1,3-dicyclohexyl-2- (3-ethylphenyl) guanidine, 1,3
-Dicyclohexyl-2- (4-ethylphenyl) guanidine, 1,3-dicyclohexyl-2- (4-allylphenyl) guanidine, 1,3-dicyclohexyl-2
-(4-Vinylphenyl) guanidine, 1,3-dicyclohexyl-2- (4-t-butylphenyl) guanidine, 1,3-dicyclohexyl-2- (4-octylphenyl) guanidine, 1,3-dicyclohexyl-2 −
(4-dodecylphenyl) guanidine, 1,3-dicyclohexyl-2- (4-octadecylphenyl) guanidine, 1,3-dicyclohexyl-2- (4-eicosylphenyl) guanidine, 1,3-dicyclohexyl-
2- (2,3-dimethylphenyl) guanidine, 1,3
-Dicyclohexyl-2- (2,4-dimethylphenyl) guanidine, 1,3-dicyclohexyl-2-
(2,5-Dimethylphenyl) guanidine, 1,3-dicyclohexyl-2- (2,6-dimethylphenyl) guanidine, 1,3-dicyclohexyl-2- (3,5-
Dimethylphenyl) guanidine, 1,3-dicyclohexyl-2- (3,4,5-trimethylphenyl) guanidine, 1,3-dicyclohexyl-2- (2,4,6-)
Trimethylphenyl) guanidine, 1,3-dicyclohexyl-2- (4-methoxyphenyl) guanidine,
1,3-dicyclohexyl-2- (4-ethoxyphenyl) guanidine, 1,3-dicyclohexyl-2- (3
-Methoxyphenyl) guanidine, 1,3-dicyclohexyl-2- (3-ethoxyphenyl) guanidine,
1,3-dicyclohexyl-2- (4-allyloxyphenyl) guanidine, 1,3-dicyclohexyl-2-
(4-Ethoxyethoxyphenyl) guanidine, 1,3
-Dicyclohexyl-2- (4-dodecyloxyphenyl) guanidine, 1,3-dicyclohexyl-2- (4
-Octadecyloxyphenyl) guanidine, 1,3
-Dicyclohexyl-2- (4-icosyloxyphenyl) guanidine, 1,3-dicyclohexyl-2-
(2-chlorophenyl) guanidine, 1,3-dicyclohexyl-2- (3-chlorophenyl) guanidine,
1,3-dicyclohexyl-2- (4-chlorophenyl) guanidine, 1,3-dicyclohexyl-2- (2
-Bromophenyl) guanidine, 1,3-dicyclohexyl-2- (3-bromophenyl) guanidine, 1,3
-Dicyclohexyl-2- (4-bromophenyl) guanidine, 1,3-dicyclohexyl-2- (2-chloro-4-methylphenyl) guanidine, 1,3-dicyclohexyl-2- (3-chloro-4-methylphenyl) ) Guanidine, 1,3-dicyclohexyl-2- (2,3,
4,5,6-Pentamethylphenyl) guanidine, 1,
3-dicyclododecyl-2- (4-methylphenyl) guanidine. These are one type or two types for one decolorizing layer.
Used in combination with one or more species. When there are a plurality of decoloring layers, the decolorizing agents may be the same or different from each other.

The decolorizer according to the present invention can be easily synthesized by a known method. For example, when R in Chemical formula 1 is a cyclohexyl group, a method using dicyclohexylcarbodiimide, which is a corresponding raw material, is effective. By the addition reaction of this with an aniline derivative corresponding to the target decoloring agent,
The desired decolorizer is obtained.

The smearing amount of the decolorizing agent according to the present invention is 0.50 g / m ² or more and 10.0 g / m ² or less per one decoloring layer. It is preferable in terms of chromaticity. Particularly preferred is 2.50 g / m ² or more and 5.0 g / m ² or less.

The decolorizing layer containing the decoloring agent may contain a binder, a sensitizer, a pigment and other additives in addition to the decoloring agent. Any of these may be the same as those used for other layers such as a heat-sensitive recording layer described later.

Next, the outline of the materials and constitution of the multicolor thermosensitive recording material of the present invention will be described. The multicolor thermosensitive recording material of the present invention comprises two or more thermosensitive recording layers each having a different coloring hue, and an erasing layer provided under at least one thermosensitive recording layer. In order to improve the color density and image storability of each thermosensitive recording layer, it is preferable to provide an intermediate layer between the thermosensitive recording layer and the decoloring layer thereunder. In addition to these, various layers can be provided as required. Each of the heat-sensitive recording layers comprises an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting compound (developing agent) as main components, and these are dispersed and coated in a binder to obtain the layer. Different coloring hues can be obtained by selecting the dye precursor. The materials used and the layer structure will be described in detail below.

As the dye precursor used in the multicolor heat-sensitive recording material of the present invention, usually a colorless or light-colored electron donating compound is preferably used. Next, specific examples will be given according to the structure, but the hues of various colors are various such as black, red, green, blue, orange, yellow, and purple. These may be selected and used so that the thermosensitive recording layers have different hues from each other. Two or more dye precursors may be used in one heat-sensitive recording layer. Specific examples of these dye precursors are listed below, but the present invention is not limited thereto.

(1) Triarylmethane compound and indolylphthalide 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- (2-methyl-4-dimethylaminophenyl) -3- (2-methylindol-3-yl) Phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-3-
Yl) phthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-dimethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,3-bis (1,2-dimethyl) Indole-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazole- 3-yl) -5-dimethylaminophthalide, 3,3-bis (2
-Phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-
(1-Methylpyrrol-2-yl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-dimethylamino-2-ethoxyphenyl) -4 -Azaphthalide, 3- (1-ethyl-
2-Methylindol-3-yl) -3- (4-dimethylamino-2-ethoxyphenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4- Dimethylamino-2-ethoxyphenyl) -4,7-diazaphthalide, 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (4-N-phenyl-N-ethylamino-2
-Ethoxyphenyl) -4-azaphthalide 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) 2-anilinofluorane (or 7-
Anilinofluorane) -based compound 3-diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinoflu Oran, 3-diethylamino-6-methyl-7- (4
-Methylanilino) fluorane, 3-diethylamino-
6-methyl-7- (4-n-butylanilino) fluorane, 3-diethylamino-6-methyl-7- (4-ethoxyanilino) fluorane, 3-pyrrolidino-6-methyl-7- (4-methylanilino) fluorane , 3-pyrrolidino-6-methyl-7- (4-n-butylanilino)
Fluoran, 3-pyrrolidino-6-methyl-7- (4-
Ethoxyanilino) fluorane, 3-di-n-propylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3-di- n-pentylamino-6-methyl-7-
Anilinofluorane, 3- (N-methyl-Nn-propyl) amino-6-methyl-7-anilinofluorane,
3- (N-ethyl-Nn-propyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N)
-Isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-amyl) amino-6-
Methyl-7-anilinofluorane, 3- (N-ethyl-
N-isobutyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N
-Methyl-N-tetrahydrofuran-2-ylmethyl)
Amino-6-methyl-7-anilinofluorane, 3-
(N-Ethyl-N-tetrahydrofurylmethyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-tetrahydrofuran-2-yl) amino-6
-Methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-
Anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-ethyl) amino-6-methyl-7-anilinofluorane,
3-Isopentylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7
-(2-Fluoroanilino) fluorane, 3-dibutylamino-6-methoxy-7-anilinofluorane, 3-
Di-n-butylamino-6-methyl-7- (2,6-dimethylanilino) fluorane, 3- (N-ethyl-N-
3-Ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-3-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6 -Methyl-7- (3-trifluoromethylanilino) fluorane, 3-diethylamino-7- (3-trifluoromethylanilino) fluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino- 7- (3-chloroanilino) fluorane, 3-di-n-butylamino-
7- (3-chloroanilino) fluorane, 3-diethylamino-7- (2-fluoroanilino) fluorane, 3
-Diethylamino-7- (2-methoxyanilino) fluorane, 3-pyrrolidino-7- (2-chloroanilino)
Fluoran, 3-pyrrolidino-7- (3-chloroanilino) fluorane, 3-pyrrolidino-7- (2-methoxyanilino) fluorane, 3-diethylamino-7- (2
-Isopentyloxycarbonylanilino) fluorane, 3- (N-ethyl-Np-tolyl) amino-6-
Methyl-7-anilinofluorane.

(4) Other fluorane compounds and xanthene compounds 3-pyrrolidino-7-cyclohexylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-n-octylaminofluorane , 3-diethylamino-7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-
Diethylamino-6-chloro-7-methylfluorane,
3-diethylamino-6-methyl-7-chlorofluorane, 3-di-n-butylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-ethylamino-6-
Chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-di-n-butylamino-7- (2-
(Chlorobenzylamino) fluorane, 3,6-dimethoxyfluorane, 3,6-diethoxyfluorane, rhodamine B anilinolactam, rhodamine B-p-chloroanilinolactam.

(5) Spiro Compounds 3-Methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- ( Spiropyran compounds such as 3-methoxybenzo) spiropyran and 3-propylspirobenzopyran,
3 ', 6'-bisdiethylamino-5-diethylaminospiro (isobenzofuran-1,9'-fluorene)-
A compound having a fluorene skeleton such as 3-one, 3 ', 6'-bisdimethylamino-5-dimethylaminospiro (isobenzofuran-1,9'-fluorene) -3-one.
3,3-bis- [2- (4-methoxyphenyl) -2-
(4-Dimethylaminophenyl) ethenyl] -4,5,
Vinylogous triarylmethane compounds such as 6,7-tetrachlorophthalide. These dye precursors can be used alone or in combination of two or more.

The coating amount of the dye precursor is 0.25 g / m ² , particularly 0.50 g / m ² for one heat-sensitive recording layer.
m ² or more is preferable for obtaining a high color density.

As the electron-accepting compound (developing agent), an acidic substance generally used in thermal paper can be preferably used. For example, a polyvalent metal salt such as a phenol derivative, an aromatic carboxylic acid derivative, an N, N'-diarylthiourea derivative, or a zinc salt of an organic compound can be used. Particularly preferred are phenol derivatives, specifically p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4- Hydroxy-4′-benzenesulfonyloxydiphenyl sulfone, 1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) cyclododecane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) ) Hexane, α, α′-bis (4-hydroxyphenyl) -1,4-diisopropylbenzene,
2,2-bis (4-hydroxyphenyl) octane,
1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane , 1,3-di- [2-
(4-Hydroxyphenyl) -2-propyl] benzene, 1,3-di- [2- (3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-di- [2-
(4-hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, 4,
4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-
4,4'-dihydroxydiphenyl sulfone, 3,3 '
-Diallyl-4,4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate, 2,2-bis (4- Hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-t-butyl-5-methylphenol), benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, 4
-Dimethyl hydroxyphthalate, benzyl gallate, octadecyl gallate, salicylanilide, 5-chlorosalicylanilide, salicylic acid, 3-isopropylsalicylic acid, 3-t-butylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) Examples include salicylic acid, 3-chloro-5- (α-methylbenzyl) salicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid, and 3,5-di-α-methylbenzylsalicylic acid. These can be used alone or in combination of two or more in each thermosensitive recording layer. Further, the same color developer or different materials may be used for the plurality of heat-sensitive recording layers.

In each heat-sensitive recording layer of the multicolor heat-sensitive recording material of the present invention, when a developer is used in an amount of 25% by weight or more and 400% by weight or less based on the dye precursor, color density, image storability and decoloring property are obtained. In terms of Particularly preferable is a case where the developer is used in an amount of 100% by weight or more and 200% by weight or less based on the dye precursor. However, in the heat-sensitive recording layer that does not require decoloring, the upper limit of the ratio of the color developer to the dye precursor is determined simply from the viewpoint of color development efficiency. In this case, if the color developer is 5000% by weight or less based on the dye precursor, the color density is good. If the amount exceeds this range, the color density may decrease although the dye precursor is colored.

The heat-sensitive recording layer according to the present invention comprises a binder,
It may also contain sensitizers, pigments and other additives. Further, the same materials as those can be used for the decoloring layer. Hereinafter, these will be described.

In the present invention, the binder used in the heat-sensitive recording layer and the erasing layer is starch, 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 acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt or ammonium of ethylene / maleic anhydride copolymer Water-soluble polymers such as salts, polyvinyl acetate, polyurethane, polyacrylic acid ester,
Examples thereof include styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, methyl acrylate / butadiene copolymers, and latexes such as ethylene / vinyl acetate copolymers. These may be used alone or in combination of two or more in each layer. Further, the binder of each layer may be the same as or different from each other.

Further, N-hydroxymethylstearic acid amide and N are used as sensitizers for improving color developing sensitivity.
-Hydroxymethyl behenic acid amide, stearic acid amide, behenic acid amide, palmitic acid amide, waxes such as 1,2-bisoctadecanoylaminoethane, urea derivatives such as octadecyl urea, 2-benzyloxynaphthalene, 1-benzyl Naphthol derivatives such as oxy-4-methoxynaphthalene, p-benzylbiphenyl, 4
-Biphenyl derivatives such as allyloxybiphenyl and m-terphenyl, 1,2-bis (3-methylphenoxy)
Polyether compounds such as ethane, 1,2-diphenoxyethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, bis oxalate ( Carbonic acid or oxalic acid diester derivatives such as p-methylbenzyl) ester, sulfonic acid esters such as 2,4,6-trimethylbenzenesulfonic acid p-methylphenyl ester, and the like may be added in combination to each thermosensitive recording layer. it can. When a sensitizer is used, it is 10 for the color developer.
The preferable addition amount is ˜2000% by weight. These sensitizers can also be added to the decoloring layer in order to increase the decoloring sensitivity (decoloring with lower energy).

Pigments that can be added to each layer of the multicolor thermosensitive recording material of the present invention include diatomaceous earth, talc, kaolin, calcined kaolin, light or heavy calcium carbonate, calcium silicate, magnesium carbonate, basic magnesium carbonate,
Examples thereof include barium sulfate, titanium dioxide, zinc oxide, silicon dioxide, silicic acid, aluminum hydroxide, alumina, urea-formalin resin and polystyrene resin.

In addition, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearic acid amide and castor wax are used for the purpose of preventing head wear and sticking. In addition, a dispersant such as sodium dioctylsulfosuccinate, an ultraviolet absorber such as a benzophenone-based or a benzotriazole-based, a surfactant, a fluorescent dye, and the like are added to each layer such as a heat-sensitive recording layer and a decoloring layer as necessary. . Specific examples of the surfactant include polyalkylene glycols such as polyethylene glycol, polypropylene glycol or copolymers thereof.

The support used in the present invention is paper,
Various non-woven fabrics, woven fabrics, plastic films such as polyethylene terephthalate, polypropylene and polystyrene,
A film laminated paper laminated with a synthetic resin such as polyethylene, polypropylene, polyethylene terephthalate, or polystyrene, a synthetic paper, a metal foil such as aluminum, a glass, or the like, or a composite sheet in which these are combined can be arbitrarily used depending on the purpose. However, the present invention is not limited to these. These may be opaque, transparent or translucent. White pigments, colored dyes and pigments, bubbles and the like may be contained in the support or on the surface thereof in order to make the background look white and other specific colors. In particular, when the hydrophilicity of the support is small and it is difficult to smear it when performing aqueous smearing on films etc., hydrophilic treatment of the surface by corona discharge etc. and easy adhesion treatment such as coating various polymers on the surface of the support You may In addition to this, a treatment necessary for curl correction, antistatic property, or improvement of running property may be performed.

If necessary, an undercoat layer may be provided between the lowermost heat-sensitive recording layer and the support in order to improve the running property of the multicolor heat-sensitive recording material of the present invention and the color-developing sensitivity of each heat-sensitive recording layer. Can be done. In that case, hollow particles or pigments may be used in the undercoat layer.

When hollow particles are used for the undercoat layer, examples of the material thereof include polymers such as polystyrene, styrene-acrylic copolymer, polyethylene, polypropylene, melamine-formalin resin, and various nylons. There are various known methods for making the inside of particles hollow.

When a pigment is used for the undercoat layer, examples of the pigment include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, basic magnesium carbonate, titanium dioxide, zinc oxide, silicon dioxide, silicic acid, alumina, Examples thereof include inorganic pigments such as aluminum hydroxide, barium sulfate and calcium silicate, and organic pigments such as urea-formalin resin, polystyrene resin, polyethylene resin, polypropylene resin, benzoguanamine resin and various grain starches. Two or more kinds of these pigments or hollow particles may be used in combination. Incidentally, these pigments and hollow particles may be contained in the heat-sensitive recording layer.

If desired, a water-soluble polymer or latex can be used in the undercoat layer.
Specific examples thereof include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid soda, acrylic acid amide / acrylic acid ester copolymer,
Water-soluble polymer such as acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt or ammonium salt of ethylene / maleic anhydride copolymer, poly Vinyl acetate, polyurethane, polyacrylic acid ester, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer,
Examples of the latex include ethylene / vinyl acetate copolymer, ethylene / vinyl chloride copolymer, polyvinyl chloride, ethylene / vinylidene chloride copolymer, polyvinylidene chloride and the like. These water-soluble polymers or latexes can also be used in the heat-sensitive recording layer and the decoloring layer. The water-soluble polymer or latex used in each of the undercoat layer, the thermosensitive recording layer and the decolorizing layer may be the same or different.

When a water-soluble polymer, a latex or a mixture thereof is used in the undercoat layer, the amount used is 5% or more by weight ratio based on the solid content (solid content is the total of pigments or hollow particles), and more preferably Is preferably 10% or more in terms of adhesive strength. However, the weight of the hollow particles includes the weight of the liquid when it contains liquid.

When the undercoat layer contains a pigment or hollow particles, the pigment or hollow particles may be made into an emulsion or water dispersion together with a known dispersant, etc., if necessary, and the support or water-soluble polymer may be applied to the support. There is a method to smear. The amount of smearing of the undercoat layer is preferably 0.50 g / m ² or more and 20 g / m ² or less (in hollow particles, a value excluding volatile components inside the particles). If it is less than that, the effect of improving the color developing sensitivity of each thermosensitive recording layer is not sufficient. On the other hand, if it exceeds that, it may be difficult to uniformly obtain a smooth surface.

A protective layer may be provided on the multicolor thermosensitive recording material of the present invention. The protective layer is formed mainly of a film-forming material such as polyvinyl alcohol listed in the specific examples of the binder of the heat-sensitive recording layer, such as a water-soluble polymer and latex. Further, water-soluble polymers and latexes whose specific examples are listed in the section of the undercoat layer can also be used for the protective layer. In addition to them, ammonium alginate can be used for the protective layer. In that case, a compound having an epoxy group, a hardening agent such as zirconium salt, or a crosslinking agent can be added. In addition, a light and electron beam curable resin or a thermosetting resin may be smeared and cured to form a protective layer. Alternatively, a film may be laminated to form a protective layer. For example, the various films mentioned in the section of description of the support are used for lamination. In any of the above cases, the pigments described below may be mixed and smeared in order to further improve the writability and runnability. The average particle size of the pigment used in the protective layer is preferably 0.4 μm or less because the color density of each heat-sensitive recording layer is increased. The protective layer may be composed of a plurality of layers of 2 layers or 3 layers or more.

For the protective layer, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, basic magnesium carbonate, titanium dioxide, zinc oxide, silicon dioxide, aluminum hydroxide, alumina, barium sulfate, silicic acid, calcium silicate. , Urea-formalin resin and the like may be contained. These pigments may be contained in the heat-sensitive recording layer, the decolorizing layer, the intermediate layer, the undercoat layer or the backcoat layer at the same time. Besides, higher fatty acid metal salts such as zinc stearate, calcium stearate, barium stearate, paraffin,
Contains waxes such as paraffin oxide, polyethylene, polyethylene oxide, stearamide, castor wax, and dispersants such as sodium dioctyl sulfosuccinate, as well as surfactants, fluorescent dyes, colored dyes, UV absorbers, etc. You can also let it.

Next, a description will be given of the case where the thermosensitive recording layers are separated or an intermediate layer is provided. With respect to each of the heat-sensitive recording layers, each component may be contained in each one layer or the compounding ratio may be changed for each layer to form a multilayer having two or more layers. In this case, an intermediate layer (isolation layer) may be provided between two or more thermosensitive recording layers using the same material as the protective layer. Hereinafter, in the present invention, a layer provided between the heat-sensitive recording layer and the decoloring layer thereunder will be referred to as an intermediate layer, and the other intermediate layers will be referred to as isolation layers for distinction. The separating layer may be provided between the erasing layer and the thermosensitive recording layer thereunder. Further, it is preferable to provide an intermediate layer between the heat-sensitive recording layer and the decoloring layer thereunder in order to improve the color density and the image storability.
In the present invention, when each heat-sensitive recording layer is separated into two or more layers, the ratio of the dye precursor and the developer and the amount of smear contained in them are also the case of the heat-sensitive recording layer as a single layer described above. Is the same as.

Further, in the heat-sensitive recording layer and / or on the surface opposite to the surface on which another layer and / or the heat-sensitive recording layer is provided, a material capable of recording information electrically, optically or magnetically is included. But good. Further, a back coat layer may be provided on the surface opposite to the surface on which the heat-sensitive recording layer is provided for the purpose of preventing blocking, curling, preventing electrification, improving runnability and the like. Alternatively, a single or a plurality of heat-sensitive recording layers or decoloring layers may be provided on both surfaces of the support.

Next, the printing method of the multicolor thermosensitive recording material of the present invention will be described. The multicolor heat-sensitive recording material of the present invention can obtain multicolor images of desired plural hues depending on the difference in printing energy. The printing method and apparatus are the same as those for the monochromatic heat-sensitive recording material except that the printing energy is changed according to the hue.

[0042]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The parts and% shown below are based on weight.

Example 1 Preparation of multicolor thermosensitive recording material (for two colors) (A) Preparation of second color red-orange coloring thermosensitive coating liquid 3-diethylamino-6-methyl-7-, which is a red-orange coloring dye precursor Chlorofluorane (300 parts) was pulverized with a paint conditioner together with a 2.5% polyvinyl alcohol aqueous solution (700 parts) to obtain a dye precursor dispersion liquid. Then add 300 parts of bis (4-hydroxyphenyl) sulfone 2.
It was pulverized with a paint conditioner together with 700 parts of a 5% polyvinyl alcohol aqueous solution to obtain a developer dispersion. After mixing these two kinds of dispersions, the following were added with stirring and mixed well to prepare a second color red-orange color heat-sensitive coating liquid. Silicic acid 30% dispersion liquid 1000 parts 10% polyvinyl alcohol aqueous solution 900 parts water 3000 parts

(B) Preparation of coating liquid for decolorizing layer 1,3-dicyclohexyl-2- (2,5) which is a decoloring agent
300 parts of dimethylphenyl) guanidine was pulverized together with 700 parts of a 2.5% polyvinyl alcohol aqueous solution with a paint conditioner to obtain a decoloring agent dispersion liquid. The following materials were added to this with stirring and mixed well to obtain a decolorizable layer coating liquid. 10% polyvinyl alcohol aqueous solution 600 parts 10% polyethylene glycol aqueous solution 75 parts water 325 parts

(C) Preparation of intermediate layer coating liquid The following materials were mixed well to prepare an intermediate layer coating liquid. Vinyl acetate / ethylene / vinyl chloride terpolymer 50% emulsion 60 parts 10% polyvinyl alcohol aqueous solution 700 parts water 670 parts The vinyl acetate / ethylene / vinyl chloride terpolymer emulsion used here is manufactured by Sumitomo Chemical; The product name is Sumika Flex 850.

(D) Preparation of 1st color black coloring heat-sensitive coating liquid 3-di-n-butylamino-6 which is a black coloring dye precursor
2.5% of 300 parts of methyl-7-anilinofluorane
It was pulverized with a paint conditioner together with 700 parts of a polyvinyl alcohol aqueous solution to obtain a dye precursor dispersion. Then, 300 parts of 1,1-bis (4-hydroxyphenyl) cyclohexane was pulverized with 700 parts of a 2.5% polyvinyl alcohol aqueous solution in a paint conditioner,
A developer dispersion was obtained. Next, 300 parts of 2-benzyloxynaphthalene was added to a 2.5% polyvinyl alcohol aqueous solution 7
It was pulverized together with 00 parts with a paint conditioner to obtain a sensitizer dispersion liquid. After mixing these three types of dispersions, the following were added under stirring and mixed well to prepare a first color black color heat-sensitive coating liquid. Aluminum hydroxide 30% dispersion liquid 1000 parts 10% polyvinyl alcohol aqueous solution 1200 parts water 1600 parts

(E) Preparation of Isolation Layer Coating Liquid An 8% polyvinyl alcohol aqueous solution was used as the isolation layer coating liquid.

(F) Preparation of Protective Layer Coating Liquid The following materials were well mixed to prepare a protective layer coating liquid. Aluminum hydroxide 25% dispersion 20 parts 10% polyvinyl alcohol aqueous solution 100 parts water 80 parts

(G) Preparation of multicolor heat-sensitive recording material Each of the coating solutions prepared in (A) to (F) was foamed polyethylene terephthalate (manufactured by Toray; trade name Lumirror E62 # 18).
8) Apply the second color red-orange color heat-sensitive coating liquid, the isolation layer coating liquid, the decoloring layer coating liquid, the intermediate layer coating liquid, the first color black-coloring heat-sensitive coating liquid, and the protective layer coating liquid in this order to obtain a multicolor heat-sensitive coating. A recording material was obtained. Note that each solution was smeared and dried, and then calendered. Further, coating amount of each layer, the second color red orange color heat-sensitive recording layer is 2.0 g / m ^2, isolating layer is 0.5 g / m ^2, 3 decolorizing layer as a decolorizer coating amount.
0 g / m ² , the intermediate layer was 0.7 g / m ² , the first color black color thermosensitive recording layer was 3.0 g / m ² , and the protective layer was 1.0 g / m ² .

Example 2 The amount of the decoloring agent applied to the decoloring layer in Example 1 was 2.5 g / m.
^A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that the number ² was changed.

Example 3 The amount of the decoloring agent smeared on the decoloring layer in Example 1 was 4.0 g / m 2.
^A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that the number ² was changed.

Example 4 The decolorizing agent used in Example 1 was replaced with 1,3-dicyclohexyl-
A multicolor heat-sensitive recording material was obtained in the same manner as in Example 1 except that 2- (4-methoxyphenyl) guanidine was used.

Example 5 The decolorizing agent used in Example 1 was replaced with 1,3-dicyclohexyl-
A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that 2- (4-methylphenyl) guanidine was used.

Example 6 The 3-di-n-butylamino-6-methyl-7-anilinofluorane used in Example 1 was converted into 3- (1-ethyl-2-).
Multicolor heat-sensitive recording was performed in the same manner as in Example 1 except that methylindol-3-yl) -3- (4-dimethylamino-2-ethoxyphenyl) -4-azaphthalide was used instead of blue as the first hue. Got the material.

Example 7 Example 3 was repeated except that the crystal color violet lactone was used instead of 3-di-n-butylamino-6-methyl-7-anilinofluorane used in Example 1 and the first hue was blue. A multicolor thermosensitive recording material was obtained in the same manner as in Example 1.

Example 8 3-diethylamino-6-methyl-7 used in Example 1
A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that 3-diethylamino-7,8-benzofluorane was used in place of -chlorofluorane, and the second hue was red.

Example 9 3-diethylamino-6-methyl-7 used in Example 1
A multicolor heat-sensitive recording material was obtained in the same manner as in Example 1 except that 3-diethylamino-7-chlorofluorane (coloring red orange) was used instead of -chlorofluorane.

Example 10 The procedure of Example 1 was repeated except that the 1,1-bis (4-hydroxyphenyl) cyclohexane used in Example 1 was replaced with 2,2-bis (4-hydroxyphenyl) propane. A color heat-sensitive recording material was obtained.

Example 11 Same as Example 1 except that 1,2-bis (4-hydroxyphenyl) cyclohexane used in Example 1 was replaced with methyl 2,2-bis (4-hydroxyphenyl) acetate. A multicolor thermosensitive recording material was obtained.

Example 12 Example 1 was repeated except that 1,2-bis (4-hydroxyphenyl) cyclohexane used in Example 1 was replaced with butyl 2,2-bis (4-hydroxyphenyl) acetate. A multicolor thermosensitive recording material was obtained.

Example 13 A multicolor heat-sensitive recording material was obtained in the same manner as in Example 1 except that 1,1-bis (4-hydroxyphenyl) cyclohexane used in Example 1 was replaced with benzyl 4-hydroxybenzoate. It was

Example 14 1000 parts of the first color black color heat-sensitive coating liquid in Example 1 was used 2
A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that the amount of the benzyloxynaphthalene dispersion was increased to 2000 parts. The first-color black color heat-sensitive recording layer was applied so that the dye precursor application amount was the same as in Example 1.

Example 15 A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that N-hydroxymethylstearic acid amide was used instead of 2-benzyloxynaphthalene used in the first color black color thermosensitive coating solution in Example 1. Got

Example 16 Preparation of multicolor heat-sensitive recording material (in the case of three colors) (a) Preparation of third color red-orange color heat-sensitive coating solution In the same manner as the second color red-orange color heat-sensitive coating solution in Example 1, 3 A red-orange colored heat-sensitive coating liquid was obtained.

(B) Preparation of Decoloring Layer Coating Liquid, Intermediate Layer Coating Liquid, Isolation Layer Coating Liquid and Protective Layer Coating Liquid The decoloring layer coating liquid, intermediate layer coating liquid, isolation layer coating liquid and protective layer in Example 1 In the same manner as the coating liquid, a decolorizing layer coating liquid, an intermediate layer coating liquid, an isolation layer coating liquid and a protective layer coating liquid were obtained.

(C) Preparation of second color blue color heat-sensitive coating liquid 3- (1-ethyl-2-methylindol-3-yl) -3- (4-dimethylamino-) which is a blue color dye precursor.
300 parts of 2-ethoxyphenyl) -4-azaphthalide was pulverized with a paint conditioner together with 700 parts of a 2.5% polyvinyl alcohol aqueous solution to obtain a dye precursor dispersion liquid. Then 1,1-bis (4-hydroxyphenyl)
600 parts of cyclohexane and 1400 parts of a 2.5% aqueous solution of polyvinyl alcohol were pulverized with a paint conditioner to obtain a developer dispersion. After mixing these two dispersions, add the following while stirring and mix well:
A blue color heat-sensitive coating liquid was prepared. Aluminum hydroxide 30% dispersion liquid 1000 parts 10% polyvinyl alcohol aqueous solution 1200 parts water 1600 parts

(D) Preparation of first color black color heat-sensitive coating liquid In the same manner as in the first color black color development heat-sensitive coating liquid, a first color black color heat-sensitive coating liquid was obtained.

(E) Preparation of multicolor heat-sensitive recording material Each of the coating solutions prepared in (a) to (d) was foamed polyethylene terephthalate (manufactured by Toray; trade name Lumirror E62 # 18).
8) On top, a third color red-orange coloring heat-sensitive coating liquid, a separating layer coating liquid, a decoloring layer coating liquid, an intermediate layer coating liquid, a second color blue coloring heat-sensitive coating liquid, a separating layer coating liquid, a decoloring layer coating liquid, an intermediate Layer coating liquid, 1st color black color heat sensitive coating liquid,
The protective layer coating liquid was applied in this order to obtain a multicolor heat-sensitive recording material. Note that each solution was smeared and dried, and then calendered. (Here, the isolation layer coating liquid, the decolorizing layer coating liquid, and the intermediate layer coating liquid are each used twice, and a plurality of layers are obtained correspondingly. In order to distinguish these layers, Depending on the color of the heat-sensitive recording layer on those layers, it is called, for example, the decolorizing layer for the second color.) The smear amount of each layer is shown in order from the lower layer. The third color red-orange color thermosensitive recording layer 2.0g
/ M ² , the separation layer for the second color is 0.5 g / m ² , the decoloring layer for the second color is 3.0 g / m ² as the decoloring agent smear, and the intermediate layer for the second color is 0.7 g / m ² . The second color blue color thermosensitive recording layer is 2.
5 g / m ² , 0.5 g / m ² for the first color separating layer, 3.0 g / m ^{2 for} the first color erasing layer, 0.7 g / m ² for the first color intermediate layer The first color black color thermosensitive recording layer was 3.0 g / m ² , and the protective layer was 1.0 g / m ² .

Example 17 A multicolor thermosensitive recording material was obtained in the same manner as in Example 16 except that the amount of the decoloring agent applied to the decolorizing layer for the first color in Example 16 was 2.5 g / m ² .

Example 18 A multicolor heat-sensitive recording material was obtained in the same manner as in Example 16 except that the amount of the decolorizing agent applied to the second color decoloring layer was changed to 5.0 g / m ² .

Example 19 A multicolor thermosensitive recording material was obtained in the same manner as in Example 16 except that the decoloring agent used in Example 16 was changed to 1,3-dicyclohexyl-2- (4-methoxyphenyl) guanidine. It was

Example 20 A multicolor thermosensitive recording material was obtained in the same manner as in Example 16 except that the decoloring agent used in Example 16 was changed to 1,3-dicyclohexyl-2- (4-methylphenyl) guanidine. It was

Example 21 The three dye precursors used in Example 16 were used, and the first color was 3-
Diethylamino-6-methyl-7-chlorofluorane has the second color 3- (1-ethyl-2-methylindol-3-yl) -3- (4-dimethylamino-2-ethoxyphenyl) -4-azaphthalide. And the third color is 3-di-
Example 16 except that the colors were changed to n-butylamino-6-methyl-7-anilinofluorane and the hues of the first, second, and third colors were sequentially reddish orange, blue, and black.
A multicolor thermosensitive recording material was obtained in the same manner as.

Example 22 3-Di-n-butylamino-6-methyl-7-anilinofluorane used in Example 16 was treated with 3- (N-ethyl-N).
A multicolor heat-sensitive recording material was obtained in the same manner as in Example 16 except that -isoamyl) amino-6-methyl-7-anilinofluorane (black color development) was used.

Example 23 3-Diethylamino-6-methyl-used in Example 16
7-chlorofluorane was converted into 3-diethylamino-7,8-
A multicolor heat-sensitive recording material was obtained in the same manner as in Example 16 except that benzofluoran was used and the hue of the third color was red.

Example 24 3-Diethylamino-6-methyl-used in Example 16
A multicolor thermosensitive recording material was obtained in the same manner as in Example 16 except that 7-chlorofluorane was replaced with 3-diethylamino-7-chlorofluorane (coloring red orange).

Example 25 The procedure of Example 16 was repeated except that 1,1-bis (4-hydroxyphenyl) cyclohexane used in Example 16 was replaced with 2,2-bis (4-hydroxyphenyl) propane. A color heat-sensitive recording material was obtained.

Example 26 Example 16 was repeated except that 1,2-bis (4-hydroxyphenyl) cyclohexane used in Example 16 was replaced with methyl 2,2-bis (4-hydroxyphenyl) acetate. A multicolor thermosensitive recording material was obtained.

Example 27 The procedure of Example 16 was repeated except that 1,2-bis (4-hydroxyphenyl) cyclohexane used in Example 16 was replaced with butyl 2,2-bis (4-hydroxyphenyl) acetate. A multicolor thermosensitive recording material was obtained.

Example 28 A multicolor heat-sensitive recording material was obtained in the same manner as in Example 16 except that 1,1-bis (4-hydroxyphenyl) cyclohexane used in Example 16 was replaced with benzyl 4-hydroxybenzoate. It was

Example 29 A multicolor thermosensitive recording material was prepared in the same manner as in Example 1 except that the amount of the 2-benzyloxynaphthalene dispersion liquid used in Example 16 in the first color black color thermosensitive coating liquid was increased to 2000 parts. Obtained. The first-color black color heat-sensitive recording layer was applied so that the dye precursor application amount was the same as in Example 16.

Example 30 A multicolor thermosensitive recording material was prepared in the same manner as in Example 17 except that N-hydroxymethylstearic acid amide was used instead of 2-benzyloxynaphthalene used in the first color black color thermosensitive coating liquid in Example 17. Got

Example 31 2,2-Used in the third color red-orange coloring heat-sensitive coating liquid in Example 16
A multicolor heat-sensitive recording material was obtained in the same manner as in Example 16 except that octadecyl gallate was used instead of bis (4-hydroxyphenyl) sulfone.

Comparative Example 1 A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that the decoloring layer provided in Example 1 was omitted.

Comparative Example 2 The decolorizing agent used in Example 1 was 1,3-dicyclohexyl-
A multicolor thermosensitive recording material was obtained in the same manner as in Example 1 except that 2-phenylguanidine was used.

Comparative Example 3 A multicolor thermosensitive recording material was obtained in the same manner as in Example 16 except that both the first color erasing layer and the second color erasing layer provided in Example 16 were removed.

Comparative Example 4 Example 16 was repeated except that the decoloring agent used in Example 16 was changed to 1,3-dicyclohexyl-2-phenylguanidine.
A multicolor thermosensitive recording material was obtained in the same manner as.

Printing test The multicolor thermosensitive recording materials obtained in Examples 1 to 31 and Comparative Examples 1 to 4 were printed with Kyocera print head KJT-256-8MGF.
Okura Electric Thermal Printing Tester TH-P with 1
Gradation printing was performed using an MD under the condition of an applied voltage of 26 V within a printing pulse width range of 0.3 to 1.2 milliseconds. The printing energy per unit area in this printing test is 15 mJ by changing the conditions such as the printing pulse period.
/ Mm ^{2 to} 100 mJ / mm ² or less. (Hereinafter, the printing energy per unit area is simply referred to as printing energy.) The optical density of the printing portion and the like was measured using a densitometer Macbeth RD918. The optimum filter was selected according to the color hue. For reddish orange, a red measuring filter was used. Comparative Example 1
In Comparative Example 3, when a blurred image due to color mixture was obtained, a black measuring filter was used.

Printing Test Results of Two-Color Multicolor Thermosensitive Recording Materials The two-color multicolor thermal recording materials of Examples 1 to 15 and Comparative Examples 1 and 2 are necessary for obtaining the first color image. printing energy was ^{25mJ / mm 2 ~35mJ / mm 2} . The optical densities of the first colors of Examples 1 to 15 and Comparative Example 1 were 0.90 or more, which was good. However, the optical density of the first color in Comparative Example 2 was low at 0.70. When the printing energy is further increased, Examples 1 to 15
In Comparative Example 2, decolorization of the first color and color development of the second color were observed successively. However, in Comparative Example 1, the first color was not erased and the second color was mixed with the first color. The printing energy required to obtain the second color image is 45 mJ / mm ^{2 to} 60 m for both Examples 1 to 15 and Comparative Example 2.
It was J / mm ² . However, in Comparative Example 1, the printing energy was increased little by little as the printing energy was increased from the first color to the second color, so that the printing energy necessary for obtaining the second color image was not clearly obtained. In addition, Example 1
.About.15 and the optical densities of the second colors of Comparative Examples 1 and 2 were 0.90 or more. However, in Examples 1 to 15 and Comparative Example 2, a vivid image was obtained according to the hue of the dye precursor used for the second color (however, when a black coloring dye was used for the second color thermosensitive recording layer, Image) was obtained, whereas the second color of Comparative Example 1 was a dark reddish black color mixed with the image of the first color, and the contrast with the image of the first color was also poor.

Printing Test Results of Multicolor Thermosensitive Recording Material of Three Color Development The three-color multicolor thermal recording materials of Examples 16 to 31 and Comparative Examples 3 to 4 are necessary for obtaining the first color image. printing energy was ^{25mJ / mm 2 ~35mJ / mm 2} . The optical densities of the first colors of Examples 16 to 31 and Comparative Example 3 were 0.90 or more, which was a good result. However, the optical density of the first color in Comparative Example 4 was as low as 0.69. When the printing energy is further increased,
In 6 to 31 and Comparative Example 4, decolorization of the first color and color development of the second color were observed successively. Required printing energy to obtain a color image of the second color was 45mJ / mm ² ~60mJ / mm ² for any of the Comparative Example 4 Example 16-31. However, in Comparative Example 3, since the printing energy was increased from the first color to the second color, the printing energy gradually changed.
The printing energy required to obtain a color-developed image was not explicitly required. The optical densities of the second colors of Examples 16 to 31 and Comparative Examples 3 to 4 were 0.90 or more, which was a good result. In addition, in Examples 16 to 31 and Comparative Example 4, vivid images were obtained according to the coloring hue of the dye precursor used for the second color. However, 2 of Comparative Example 3
The color was dull bluish black mixed with the first color, and the contrast with the image of the first color was also poor. When the printing energy is made higher than this, the results of Examples 16 to
In 31 and Comparative Example 4, decolorization of the second color and color development of the third color were observed successively. 3 required printing energy to obtain a color image of the color was 80mJ / mm ² ~90mJ / mm ² for any of the Comparative Example 4 Example 16-31. In Comparative Example 3, the third color could not be distinguished from the second color. The optical densities of the third colors of Examples 16 to 31 and Comparative Example 4 were 0.90 or more, which was good. or,
In each of Examples 16 to 31 and Comparative Example 4, an image of the third color that was vivid according to the hue of the dye precursor used for the third color (however, when a black coloring dye was used in the third color thermosensitive recording layer Image) was obtained. However, in Comparative Example 3, when printing at high energy, it was not possible to distinguish between the second color and the third color by observing the hue.

Humidity and heat resistance storage test of images, etc. Examples 1 to 31 and Comparative Examples 1 to 4 obtained in the above printing test.
2) Place the printed part and the background, where the highest density was obtained for each hue image, in a constant temperature tank at 40 ° C and 90% RH.
The image and the background density after standing for 4 hours were measured. In Examples 1 to 31, Comparative Example 1 and Comparative Example 3, the image residual rate was over 90% for images of any hue. (The third color of Comparative Example 3 cannot be tested because an image that can be judged to be the third color is certainly not obtained.) Further, the image residual ratio of the second color of Comparative Example 2 and the third color of Comparative Example 4 also exceeded 90%. However, Comparative Example 2
The image residual ratios of the first color image and the first and second color images of Comparative Example 4 were 74%, 76%, and 79%, respectively. In the above test, no change in color hue or background fog was observed in any of the samples.

Heat-resistant storage stability test for images, etc. Examples 1 to 31 and Comparative Examples 1 to 4 obtained in the above printing test.
2) Place the printed part and the background, where the highest density was obtained for each hue image, in a constant temperature bath at 60 ° C and 10% RH.
The image and the background density after standing for 4 hours were measured. In Examples 1 to 31, Comparative Example 1 and Comparative Example 3, the image residual rate was higher than 80% for images of any hue. (The third color of Comparative Example 3 cannot be tested because an image that can be judged to be the third color is certainly not obtained.) Further, the image residual rates of the second color of Comparative Example 2 and the third color of Comparative Example 4 also exceeded 80%. However, Comparative Example 2
The image residual ratios of the first color image and the first and second color images of Comparative Example 4 were 48%, 49%, and 52%, respectively. In the above test, no change in color hue or background fog was observed in any of the samples.

[0093]

As is apparent from the examples, there is a decoloring layer containing the decoloring agent represented by Chemical Formula 1 below at least one thermosensitive recording layer, preferably a thermosensitive recording layer and a layer below it. By providing an intermediate layer between the color erasing layer and the color erasing layer, a multicolor thermosensitive recording material excellent in color density of the first color and image storability could be obtained.

Claims (1)

[Claims] 1. A multicolor thermosensitive recording material having two or more thermosensitive recording layers each of which develops a different hue on a support, and a multicolor image of two or more colors is obtained by a difference in printing energy. A multicolor thermosensitive recording material comprising a decoloring layer containing a decoloring agent represented by the following general formula 1 below the thermosensitive recording layer. Embedded image (However, R represents a cycloalkyl group. Z represents 1 carbon atom.
Represents an alkyl group having 20 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aralkyl group having 7 to 10 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a halogen atom. n represents an integer of 1 to 5. When the substituent Z contains a carbon-carbon single bond, an oxygen atom may be inserted between them. Also, the substituent Z
When contains an alkyl chain, part of it may be an unsaturated bond. When n is 2 or more, 2 or more Zs may be the same or different from each other. However, the compound of Chemical formula 1 has one or less halogen atoms. )