JPH05201126A - Two-color heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To provide a two-color heat-sensitive recording material wherein recording images of a high-temperature recording layer and low-temperature recording layer are free from an additive color and have few blur. CONSTITUTION:In a two-color heat-sensitive recording material which is obtained by providing in order a high-temperature recording layer and low- temperature recording layer on a substrate, which are recorded in different color tones by reaction between leuco-dye and a coloration agent, this is the two-color heat-sensitive recording material wherein the low-temperature recording layer is comprised of the recording layer which is made to contain the leuco-dye color-developed by the coloration agent, the coloration agent and an achromatic agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-color 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 required performance and quality have been diversified with the expansion of applications, and for example, high sensitivity, image stabilization, two-color recording and the like are mentioned. Especially for two-color recording, which has a wide range of applications, many proposals have been made regarding recording materials, layer configurations, and the like. The two-color heat-sensitive recording methods that utilize the reaction between a conventional leuco dye and a color developing agent are roughly classified into the following two methods. 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 two-color thermosensitive recording medium in which the recorded images on the high-temperature recording layer and the low-temperature recording layer have no color addition and have less bleeding.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a support,
In a two-color thermosensitive recording medium in which a high-temperature recording layer and a low-temperature recording layer are sequentially provided, which are recorded in different color tones by the reaction of a leuco dye and a color-developing agent, the low-temperature recording layer is colored with a colorant. It has been found that by using a recording layer containing a leuco dye, a coloring agent, and a decoloring agent, a two-color thermosensitive recording medium can be obtained in which the recorded image in each recording layer has no color addition and little bleeding. The invention was completed.

[0007]

As described above, the two-color thermosensitive recording medium of the present invention is provided with the high-temperature recording layer and the low-temperature recording layer in this order on the support, and the low-temperature recording layer further comprises a leuco dye and a color-developing color-developing agent. An important feature is that it consists of a recording layer containing an agent and a decoloring agent, and an intermediate layer containing a binder and a pigment as main components is provided between the high temperature recording layer and the low temperature recording layer. As a result, it is possible to obtain a clear recorded image of the high-temperature recording layer having excellent storage stability.

In the two-color heat-sensitive recording material of the present invention, for example, in order to obtain a positive recording image, positive recording is performed on a 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.

In the present invention, various known colorless or light-colored leuco dyes can be used as the leuco dye used in each recording layer. Specifically, for example, 3,3-bis (p-
Dimethylaminophenyl) -6-dimethylaminophthalide, 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)
Fluoran, 3-di (n-butyl) amino-7- (o-
Fluorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p- Truizino) Fluoran, 3- (N-
Ethyl-N-furfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-
7-anilinofluorane, 3- (N-methyl-Nn-)
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'-xanthen-2'-ylamino] phenyl} propane, 3,
6,11-tri (dimethylamino) fluorane, 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-dimethoxyfluorane, 3,6-dibutoxyfluorane, etc. Can be mentioned. 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 colored by the coloring agent used in the low-temperature recording layer can be obtained by heating and melting the above-mentioned leuco dye and the coloring agent together or by dissolving them in an organic solvent and then removing the organic solvent. .. 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.

The decoloring agent added to 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 adduct of terephthalic acid
55-25306), long-chain 1,2-glycol (JP-A-55-272)
17), glycerin fatty acid ester (JP-A-55-152)
094), urea derivatives (JP-A-55-139290), and alkylene oxide adducts of straight-chain glycols (JP-A-58-139290).
55-152094), morpholine derivatives (JP-A-56-405)
88), polyether and polyethylene glycol derivatives (Japanese Patent Publication No. 50-17867, Japanese Patent Publication No. 50-17868),
Guanidine derivative (51-29024), amine or quaternary ammonium salt (JP-A-50-18048), piperidine derivative (JP-A-64-82986), aromatic amide derivative (JP-A-294583) Issue)) etc.

The above various decoloring agents are used in an amount of 50 to 100 relative to the total amount of the leuco dye and the color developing agent in the low temperature recording layer.
About 0% by weight is added. More preferably 100 to 50
It is adjusted in the range of about 0% by weight. Incidentally, it is of course possible to use two or more kinds of decolorizing agents together. Each recording layer coating material containing these substances generally uses water as a dispersion medium, and a dye, a color former, and a decolorizer are dispersed together or separately by a stirrer / pulverizer such as a ball mill, attritor, or sand mill. Prepared.

In the coating solution, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, etc. are used as usual binders in the coating liquid. Diisobutylene / maleic anhydride copolymer salt, styrene /
Maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene /
Examples thereof include 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-methylolstearic acid amide, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, dibenzyl oxalate, di-p-methylbenzyl oxalate, 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 two-color thermosensitive recording medium of the present invention, the method for forming 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, short dwell coating and curtain. The coating liquid for each recording layer is formed on a support such as paper, plastic film, synthetic paper, non-woven fabric, and metal deposition by a suitable coating method such as coating or die coating.

[0019] Each recording layer coating solution coating amount is not particularly limited, 2~12g / m ² in dry weight, preferably 3 to 7 g / m ²
Adjusted in a range of degrees. If necessary, a protective layer may be provided on the low-temperature recording layer for the purpose of protecting the recording layer,
For the purpose of improving recording sensitivity and recording image quality, it is possible to provide an undercoat layer on the support or apply a super calender after coating each layer, and also apply an adhesive treatment to the back of the recording material to process it into an adhesive label, etc. Various known techniques in the field of manufacturing thermal recording media can be added as necessary.

[0020]

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 liquid D 3- (4-diethylamino-2-methylphenyl) -3
-(4-Dimethylaminophenyl) -6-dimethylaminophthalide (blue coloring system) 10 parts, 4-hydroxy-4 '
A mixture of 10 parts of isopropoxydiphenyl sulfone and 30 parts of 1,2-di (3-methylphenoxy) ethane was developed on a hot plate at 120 ° C.

A composition comprising 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 diameter became 2 μm. ． Preparation of coating liquid for high temperature recording layer Liquid A 40 parts, liquid B 120 parts, kaolin [trade name: UW-
90, manufactured by EMC] 40 parts, 100 parts of water, and polyvinyl alcohol [trade name: PVA205, manufactured by Kuraray]
100 parts of 20% aqueous solution were mixed and stirred to prepare 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 A high-quality paper having a basis weight of 60 g / m ² was sequentially coated with a coating liquid for a high-temperature recording layer and a coating liquid for a low-temperature recording layer, and the coating amount after drying was 7 g / m ² , 3
A two-color thermosensitive recording medium was obtained by coating and drying so that the coating amount would be g / m ^2, and applying it on a super calender. [Example 2] Preparation of intermediate layer paint Kaolin [trade name: UW-90, manufactured by EMC] 10 parts,
30 parts of water, and polyvinyl alcohol [trade name: PV
A110, manufactured by Kuraray Co., Ltd.] 100 parts of 15% aqueous solution was mixed and stirred to obtain a coating liquid. Crushed until

Same as Example 1 except that the above intermediate layer coating material was applied and dried between the high temperature recording layer and the low temperature recording layer of Example 1 so that the coating amount after drying was 2 g / m ^2. A two-color thermosensitive recording medium was obtained. [Comparative Example 1] Preparation of solution F 3- (4-diethylamino-2-methylphenyl) -3
-(4-Dimethylaminophenyl) -6-dimethylaminophthalide (blue coloring system) 10 parts, 1,2-di (3-methylphenoxy) ethane 30 parts, 5% of methylcellulose
A composition consisting of 20 parts of an aqueous solution and 100 parts of water was pulverized 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 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 On the high temperature recording layer obtained in Example 1, the decoloring layer coating liquid and the low temperature recording layer coating liquid described above were successively applied so that the coating amount after drying was 4 g.
/ M ² , 3 g / m ² , coated and dried, and supercalendered to obtain a two-color heat-sensitive recording material.

The recording characteristics of the thus obtained three kinds of two-color 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.
Recording was performed under the conditions of m, head input 0.90 W / dot, low temperature recording layer recording energy: 1.3 mJ / dot, high temperature recording layer recording energy: 3.0 mJ / dot.

The recording density of the obtained recording portion was measured with 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.

[0025]

[Table 1]

[0026]

As is apparent from the results shown in Table 1, the two-color heat-sensitive recording material of the present invention is a multi-color heat-sensitive recording image in which high-temperature recorded images and low-temperature recorded images have no color addition and less bleeding. there were.

Claims (2)

[Claims] 1. A two-color heat-sensitive recording medium in which a high-temperature recording layer and a low-temperature recording layer are sequentially formed on a support to record different color tones by the reaction of a leuco dye and a color-developing agent. Leuco dye whose recording layer is colored by a coloring agent,
A two-color thermosensitive recording medium comprising a recording layer containing a color former and a decolorizer. 2. A two-color thermosensitive recording medium according to claim 1, wherein an intermediate layer is provided between the high temperature recording layer and the low temperature recording layer.