JPH05193254A - Multi-color thermal recording medium - Google Patents

Abstract

PURPOSE:To provide a multi-color thermal recording medium which is free from any color addition to a recorded image in the high temperature recording layer and a low temperature recording layer, and hardly allows ink to run. CONSTITUTION:In multi-color thermal recording medium to be recorded in respectively different color tones due to a chemical reaction between leuco dye and a coloring agent, on a stained support, a color discharging layer is provided between the supporting body and a high temperature recording layer. In addition, the low temperature recording layer contains the leuco dye which becomes colored by the coloring agent, the coloring agent and the color discharging agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor thermosensitive recording medium having a plurality of thermosensitive recording layers recorded in different color tones.

[0002]

2. Description of the Related Art Utilizing the reaction between a leuco dye and a color developing agent,
A thermal recording material in which both substances are brought into contact with each other by heat to obtain a recorded image is well known. Since such a thermal recording medium is relatively inexpensive, and the recording device is compact and its maintenance is easy, it is used not only as a recording medium for facsimiles and printers but also in a wide range of fields.

However, the performances and qualities required have been diversified with the expansion of applications, and for example, high sensitivity, image stabilization, multicolor recording, etc. have been mentioned. In particular, for multicolor recording, which has a wide range of applications, many proposals have been made regarding recording materials, layer configurations, and the like. The conventional multicolor heat-sensitive recording methods utilizing the reaction between a leuco dye and a color former are roughly classified into the following two systems. The first method is a method in which the low temperature recording layer is colored during low temperature heating, and both the low temperature recording layer and the high temperature recording layer are colored during high temperature heating to obtain the added color. The second method is a method of obtaining a color tone of only high temperature color development by using a decoloring agent which has a decoloring effect on the color development system of the low temperature recording layer at the time of high temperature heating in the first method.

However, in the first method, it is not possible to obtain a recorded image in which only the respective recording layers are colored, and in the second method, the high temperature recording layer and the low temperature recording layer are separately recorded at high temperatures. Since it is necessary to provide an erasing layer between the recording layer and the low-temperature recording layer, more recording energy is required to record the high-temperature recording layer than in the first method. There is a drawback of blurring.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multicolor thermosensitive recording medium in which the recorded images of the high temperature recording layer and the low temperature recording layer are free from color addition and have less bleeding.

[0006]

According to the present invention, a high temperature recording layer and a low temperature recording layer, which are recorded in different color tones by the reaction of a leuco dye and a color former, are sequentially formed on a colored support. In the provided multicolor thermosensitive recording medium, a decoloring layer is provided between the support and the high temperature recording layer, and the low temperature recording layer further contains a leuco dye colored by a coloring agent, a coloring agent, and a decoloring agent. The present invention has been completed by finding that a multicolor thermosensitive recording medium can be obtained in which a recording image of each recording layer has no coloration and little bleeding by using a narrow recording layer.

[0007]

As described above, the multicolor thermosensitive recording medium of the present invention is provided with a decolorizing layer, a high temperature recording layer and a low temperature recording layer in this order on a colored support, and the low temperature recording layer is colored with a coloring agent. It has a significant feature in that it is composed of a recording layer containing a leuco dye, a coloring agent and a decoloring agent.

In the multicolor thermosensitive recording medium of the present invention, for example, in order to obtain a positive recording image, positive recording is performed on the low temperature recording layer formed of a leuco dye and a decoloring agent which are colored by a coloring agent. When a negative portion corresponding to the image is applied by a thermal head, the leuco dye formed by the action of the decoloring agent is decolored to obtain a positive recorded image. The positive portion may be applied by a thermal head to the high temperature recording layer formed of a leuco dye and a color developing agent. Further, by applying with a thermal head, the recorded image on the high temperature recording layer is erased and at the same time a clear recorded image is obtained by the colored support. In particular, in order to obtain a clear recorded image with a colored support, it is preferable that the heat-sensitive recording material used in the decoloring layer and each recording layer does not recrystallize after recording.

Incidentally, in the case of obtaining a recorded image composed of the three primary colors of red, blue and yellow, blue is obtained for the support and red is obtained for the high temperature recording layer in consideration of the transmittance of visible light and the absorption wavelength corresponding to the three primary colors. In the recording layer, the low temperature recording layer is most preferably a recording layer formed of a leuco dye that develops yellow light that absorbs blue light, and a coloring agent and a decoloring agent. In the present invention, various known colorless or light-colored leuco dyes can be used as the leuco dye used in each recording layer, and specifically, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylamino. Phthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-
Diethylamino-7-dibenzylamino-benzo [a]
Fluorane, 3- (N-ethyl-N-p-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3
-Cyclohexylamino-6-chlorofluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane,
3-diethylamino-7-chlorofluorane, 3- (N
-Ethyl-N-isoamyl) amino-6-methyl-7-
Anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di (n- Butyl) amino-6-methyl-
7-anilinofluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (n-butyl) Amino-7- (o-chlorophenylamino) fluorane, 3-diethylamino-7-
(O-Fluorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilino Fluoran, 3- (N
-Ethyl-p-toluidino) -6-methyl-7- (p-
Toluidino) fluorane, 3- (N-ethyl-N-furfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-methyl) -N-n-propylamino) -6-methyl-7-anilinofluorane, 3-p-
(P-Dimethylaminoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6'-
(N-Cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthene-2'-
Ilamino] phenyl} propane, 3,6,11-tri (dimethylamino) fluorane and the like can be mentioned. Also,
As the yellow coloring leuco dye added to the low temperature recording layer,
For example, 1- (4-methoxyphenyl) -2- (2-quinolyl) ethylene, 1- (4-octoxysilyl) -2-
(2-quinolyl) ethylene, 3- (4-diethylaminophenyl) -3- (4-ethoxycarbonylphenylamino) phthalide, 3- (4-dibutylamiphenyl)-
3- (2-chlorophenylamino) phthalide, 3,6-
Examples thereof include dimethoxyfluorane and 3,6-dibutoxyfluorane. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

Various materials are known as a colorant used in combination with the basic dye as described above, for example, activated clay, attapulgite, colloidal silica, inorganic acidic substances such as aluminum silicate, 4,4'- Isopropylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4 '
-Dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl-
4-hydroxyphenyl) sulfone, 4-hydroxy-
4'-methyldiphenyl sulfone, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, bis (p-hydroxyphenyl) butyl acetate, bis (p- Hydroxyphenyl) methyl acetate, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3- Bis [α-methyl-α-
Phenolic compounds such as (4'-hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfin, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- {3- ( p-
Tolylsulfonyl) propyloxy] salicylic acid, 5-
Aromatic carboxylic acids such as [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid, and zinc, magnesium, aluminum of these aromatic carboxylic acids,
Examples thereof include salts with polyvalent metals such as calcium, titanium, manganese, tin and nickel, and organic acid substances such as antipyrine complex of zinc thiocyanate.

The leuco dye formed by the coloring agent used in the low temperature recording layer can be obtained by heating and melting the above-mentioned various leuco dyes and the coloring agent together or dissolving them in an organic solvent and then removing the organic solvent. Be done. The use ratio of the leuco dye and the color developing agent is appropriately selected according to the type of the leuco dye or the color developing agent to be used, and is not particularly limited, but is generally 0.2 with respect to 1 part by weight of the leuco dye. ~ 10 parts by weight, preferably about 0.5-4 parts by weight of the color former is used.

Further, the decoloring agent added to the decoloring layer and the low temperature recording layer is not particularly limited, and aliphatic amines, amides, piperidines, piperazines,
Pyridines, imidazoles, imidazolines, morpholines, guanidines, amidines, polyethers,
Glycols and the like are preferably used. Specifically, for example, the following compounds are described in various known documents. Alkylene oxide compounds of bisphenols (JP-A-54-13941), ethylene oxide adducts of terephthalic acid (JP-A-55-25306), long-chain 1,2-glycol (JP-A-55-27217) Gazette), glycerin fatty acid ester (JP-A-55-152094), urea derivative (JP-A-55-1).
39290), alkylene oxide adducts of linear glycols (JP-A-55-152094), morpholine derivatives (JP-A-56-40588), polyether and polyethylene glycol derivatives (JP-B-50-17867, Japanese Patent Publication Sho 50-17868
No.), guanidine derivatives (51-29024), amines or quaternary ammonium salts (Japanese Patent Laid-Open No. 50-18048), piperidine derivatives (Japanese Patent Laid-Open No. 64-82986), and aromatic amide derivatives ( JP-A-294583).

The various decolorizing agents as described above are used in the low temperature recording layer in relation to the total amount of the leuco dye and the color developing agent in the low temperature recording layer, and in the decoloring layer, the leuco dye and the color developing agent in the medium temperature recording layer. About 50 to 1000% by weight based on the total amount is added to each recording layer. More preferably 100-500
It is adjusted in the range of about wt%. Incidentally, it is of course possible to use two or more kinds of decolorizing agents together.

The coating material for each recording layer and decolorizing layer containing these substances generally uses water as a dispersion medium, and a dye by a stirring / pulverizing machine such as a ball mill, an attritor or a sand mill.
It is prepared by dispersing a color former and a decolorizer together or separately. Starch, hydroxyethyl cellulose, methyl cellulose, as a normal binder in the coating liquid,
Carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol, silicon modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt , Ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin, melamine resin, amide resin, polyurethane resin and the like.

If desired, various auxiliary agents can be added to the coating liquid. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts. , Zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, and other waxes,
A curing agent such as glutaraldehyde or glyoxal, an antifoaming agent, a fluorescent dye, a coloring dye and the like are appropriately added.

It is also possible to use various pigments in combination, for example, inorganic pigments such as kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, activated clay and styrene microballs. , Nylon powder, polyethylene powder, urea / formalin resin filler, organic pigments such as raw starch particles, and the like.

Further, a sensitizer may be used in combination depending on the purpose. Specific examples of the sensitizer include stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebistearic acid amide, behenic acid amide, and methylenebisstearic acid. Amide, N-
Methylol stearic acid amide, 1-hydroxy-2-
Phenyl naphthoate, 2-naphthyl benzyl ether,
Dibenzyl terephthalate, p-benzyloxybenzoate benzyl, dibenzyl oxalate, oxalate-di-p-methylbenzyl, oxalate-di-p-chlorobenzyl, p
-Benzyl biphenyl, tolyl biphenyl ether, m
-Terphenyl, 1,2-di (3-methylphenoxy)
Ethane, 1,2-di (4-methylphenoxy) ethane,
1,2-di (4-methoxyphenoxy) ethane, 1,2
-Di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, p-methylthiophenylbenzyl ether, p-acetotoluidide, p-acetophenetizide,
N-acetoacetyl-p-toluidine, di (p-methoxyphenoxyethyl) ether, di (β-biphenylethoxy) benzene, 1,4-di (phenylthio) butane, p-di (vinyloxyethoxy) benzene, 1- Examples include compounds such as isopropylphenyl-2-phenylethane.

The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within a range of about 4 parts by weight or less relative to 1 part by weight of the color developing agent. In the multicolor heat-sensitive recording material of the present invention, the method for forming the decolorizing layer, the high temperature recording layer and the low temperature recording layer is not particularly limited, and examples thereof include air knife coating, varibar blade coating, pure blade coating, rod blade coating, and short circuit. Dwell coating, curtain coating,
The coating liquid for each recording layer is formed on a support such as a colored tic film, synthetic paper or non-woven fabric by a suitable coating method such as die coating. Coloring of the support includes a method of internally adding a colored dye to the support and a method of applying a coating liquid containing the colored dye on the support.

Particularly, regarding the method of forming the low temperature recording layer,
Since the low temperature recording layer is mainly composed of a leuco dye colored by a color former, a color former and a decolorizer, by selecting an insoluble solvent or vehicle for the decolorizer,
It can also be formed by flexographic printing, offset printing, letterpress printing, gravure printing, or the like. The coating amount of each recording layer coating liquid and decolorizing layer coating liquid is not particularly limited, and is 2 to 2 by dry weight.
12 g / m ^2, is preferably adjusted in the range of about 3 to 7 g / m ^2.

If necessary, a protective layer may be provided on the low-temperature recording layer for the purpose of protecting the recording layer, or a recording layer and an erasing layer or a recording layer and a recording layer for the purpose of making a recorded image clear. It is also possible to provide a barrier layer containing a binder as a main component between and. Furthermore, providing an undercoat layer on the support,
It is also possible to apply a super calendar after coating each layer, and various known techniques in the heat-sensitive recording material manufacturing field can be added as necessary, such as applying a pressure-sensitive adhesive treatment to the back surface of the recording material to process it into an adhesive label. It is a thing.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively, unless there is particular notice. [Example 1] Preparation of solution A A composition consisting of 10 parts of 3-diethylamino-7-chlorofluorane (red coloring system), 5 parts of a 5% aqueous solution of methylcellulose and 25 parts of water having an average particle diameter of 2 was measured by a sand mill.
It was pulverized to a size of μm. Preparation of solution B A composition consisting of 10 parts of 4,4'-cyclohexylidenediphenol, 5 parts of a 5% aqueous solution of methylcellulose and 25 parts of water was pulverized by a sand mill until the average particle diameter became 2 µm. Preparation of Solution C Tetrakis (1,2,2,6,6-pentamethyl-4-
Piperidyl) -1,2,3,4-butanetetracarboxylate 10 parts, 5% 5% aqueous solution of sulfone-modified polyvinyl alcohol [trade name: Gocelan L-3266, manufactured by Nippon Gosei Kagaku] and 25 parts water The product was ground with a sand mill until the average particle size became 2 μm. Preparation of D liquid 3,6-dimethoxyfluorane (yellow coloring system) 10 parts, 4
-Hydroxy-4'-isopropoxydiphenyl sulfone 10 parts, and 1,2-di (3-methylphenoxy)
A mixture consisting of 30 parts of ethane was developed on a hot plate at 120 ° C. A composition consisting of 10 parts of the above color-developing mixture, 5 parts of a 5% aqueous solution of methylcellulose, and 25 parts of water was pulverized with a sand mill until the average particle size became 2 μm.

Liquid E Preparation 10 parts of oxalic acid-p-methylbenzyl oxalate A composition consisting of 5 parts of a 5% aqueous solution of methylcellulose and 25 parts of water was ground with a sand mill until the average particle size became 2 μm. Preparation of coating liquid for decolorizing layer 360 parts of C liquid, and polyvinyl alcohol [trade name:
100 parts of a 20% aqueous solution of PVA105, manufactured by Kuraray Co., Ltd. was mixed and stirred to obtain a coating liquid. Preparation of coating liquid for high temperature recording layer Liquid A 40 parts, liquid B 120 parts, liquid E 120 parts, silicon oxide pigment [trade name: Mizuka Seal P-527, manufactured by Mizusawa Chemical Co., Ltd.]
20 parts, and polyvinyl alcohol [trade name: PVA
105, manufactured by Kuraray Co., Ltd.]
The solution was stirred to obtain a coating liquid. Preparation of coating liquid for low temperature recording layer 200 parts of D solution, 60 parts of C solution, 20 parts of 30% dispersion of paraffin wax [trade name: Hydrin P-7, manufactured by Chukyo Yushi Co., Ltd.], silicon oxide pigment [trade name: Mizuka Seal] P-52
15, manufactured by Mizusawa Chemical Co., Ltd., and 140 parts of a 10% aqueous solution of polyvinyl alcohol [trade name: PVA117, manufactured by Kuraray Co., Ltd.] were mixed and stirred to prepare a coating liquid. Formation of Recording Layer and Decoloring Layer Coating solution for decoloring layer, coating liquid for high temperature recording layer, coating liquid for low temperature recording layer are sequentially applied to high-quality paper colored with blue having a basis weight of 60 g / m ² after drying. the amount was coated and dried so as to ^{4g / m 2, 3g / m} 2, 3g / m 2, to obtain a multicolor thermal recording body is subjected super calender.

[Comparative Example 1] Preparation of solution F 3,6-dimethoxyfluorane 10 parts, 1,2-di (3
A composition consisting of 30 parts of methylphenoxy) ethane, 20 parts of a 5% aqueous solution of methylcellulose, and 100 parts of water was ground by a sand mill until the average particle size became 2 μm. Preparation of coating liquid for low-temperature recording layer 120 parts of F liquid, 80 parts of B liquid, 20 parts of 30% dispersion of paraffin wax [trade name: Hydrin P-7, manufactured by Chukyo Yushi Co., Ltd.], silicon oxide pigment [trade name: Mizuka Seal] P-52
15, manufactured by Mizusawa Chemical Co., Ltd., and 140 parts of a 10% aqueous solution of polyvinyl alcohol [trade name: PVA117, manufactured by Kuraray Co., Ltd.] were mixed and stirred to prepare a coating liquid. Formation of Recording Layer and Decoloring Layer Example 1 was applied to blue-colored high-quality paper having a basis weight of 60 g / m ^2.
The coating liquid for decoloring layer, the coating liquid for high temperature recording layer, the coating liquid for decoloring layer, and the coating liquid for low temperature recording layer obtained in the order of 4 g / m ² and 3 g / m ² after drying. ² , 3 g / m ² , 3 g / m
^A multicolor thermosensitive recording medium was obtained by applying and drying so as to obtain ^2, and applying it on a super calender.

The recording characteristics of the thus obtained two kinds of multicolor thermosensitive recording materials were evaluated by the following methods, and the results are shown in [Table 1]. [Evaluation method] A 6-dot / mm thermal head [heating resistance 300 Ω / dot, manufactured by Matsushita Electronic Parts Co., Ltd.] was used, main scanning recording speed: 130 ms / line, sub-scanning: 7.7 line / m.
m, head input 0.90 W / dot, low temperature recording layer recording energy: 1.3 mJ / dot, high temperature recording layer recording energy: 2.6 mJ / dot, high temperature recording layer erasing energy: 3.
It was recorded under the condition of 5 mJ / dot.

The recording density of the obtained recording portion was measured by a Macbeth densitometer [RD914 type, manufactured by Macbeth Co.] using filters corresponding to respective color tones. The degree of bleeding of the recorded image on the high temperature recording layer is visually determined. B: The bleeding of the recorded image is weak. X: The bleeding of the recorded image is strong.

[0026]

[Table 1]

[0027]

As is clear from the results of [Table 1], the multicolor thermosensitive recording medium of the present invention does not add color to the high-temperature recorded image, the medium-temperature recorded image and the low-temperature recorded image, and has little blurring. It was a heat-sensitive recorded image.

Claims (2)

[Claims] 1. A different color tone is recorded on a colored support by the reaction of a leuco dye and a color former.
In a multicolor thermosensitive recording medium in which a high-temperature recording layer and a low-temperature recording layer are sequentially provided, a decolorizing layer is provided between the support and the high-temperature recording layer, and the low-temperature recording layer develops a leuco dye and a color A multicolor thermosensitive recording medium comprising a recording layer containing an agent and a decoloring agent. 2. A multicolor heat-sensitive recording material according to claim 1, wherein the low-temperature recording layer comprises a recording layer containing a leuco dye which is colored yellow by a color former, a color former, and a decolorizer.