JPH0966667A - Two-color thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-color thermal recording material having only a little fog. SOLUTION: This color adding type two-color thermal recording material comprises, on a support body, a high temperature coloring layer which contains a coloring dye which colors into black color and a low temperature coloring layer which colors into a color different from that of the high temperature coloring layer. In between the high temperature coloring layer and the low temperature coloring layer, an intermediate layer having, as a main component, a pigment having an oil absorption regulated by JIS-K5101 of 50-400ml/100g is provided. The low temperature coloring layer contains at least one kind to be selected from among 3-diethyl amino-7-chlorofluoran, 3-cyclohexylamino-6- chlorofluoran, 3, 3'-bis (1-n-butyl-2-methylindole-3-yl) phthalide, 3-(4-diethyl- amino-2-methylphenyl)-3-(4-dimethylaminophenyl)-6-dimethylamino phthalide.

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 material having a low temperature coloring layer and a high temperature coloring layer which develop different colors depending on the conditions under which heat is applied from a thermal head. More specifically, when the color is developed at a low temperature, a clear color is produced with almost no color mixture of the high temperature color tone.
The present invention also relates to a two-color heat-sensitive recording material with less background fog.

[0002]

2. Description of the Related Art Conventionally, a color developing reaction between a color developing agent and a color developing agent which develops a color by contacting the color developing agent is utilized, and both color forming substances are melted by heat to bring them into contact with each other to obtain a color image. The heat-sensitive recording material is widely known. Since such a heat-sensitive recording material is relatively inexpensive and the recording device is compact and its maintenance is easy, it is used in a wide range of fields including recording media such as facsimiles, word processors and various computers.

The quality of such heat-sensitive recording materials has been diversified with the expansion of its applications, and examples thereof include high sensitivity, image stabilization, and multicolor recording. Particularly in the case of multi-color recording, there is an advantage that characters and figures to be emphasized can be more clearly displayed in a color different from those of other parts, and there is a growing demand.

Attempts have been made so far to obtain multicolor recording by utilizing the difference in heating temperature or the difference in thermal energy, and various multicolor thermosensitive recording materials have been proposed. The multicolor heat-sensitive recording material is generally obtained by sequentially laminating a high-temperature coloring layer and a low-temperature coloring layer, which develop different colors on a support, and is roughly classified into two types, a decoloring type and a color-adding type.

The decoloring type is disclosed, for example, in JP-A-50-17865.
Japanese Patent Laid-Open No. 57-14320, Japanese Patent Laid-Open No. 2-8
As disclosed in Japanese Patent No. 0287, it is a method of obtaining a color tone of only the high temperature color developing layer at the time of high temperature heating by using a decoloring agent having a decoloring effect on the color forming system of the low temperature color developing layer at the time of high temperature heating. This method has an advantage that the color tone can be freely selected, but it is necessary to add a large amount of a decoloring agent in order to obtain a sufficient decoloring effect. For this reason, the recorded image is discolored during long-term storage due to the effect of the decoloring agent, and an extra amount of heat is required to melt the decoloring agent, which causes an excessive load on the thermal head. In terms of points, it was not always satisfactory.

On the other hand, the color-added type is Japanese Patent Publication No. 49-27.
As disclosed in Japanese Patent Publication No. 708, Japanese Patent Publication No. 51-19989, Japanese Patent Laid-Open No. 51-146239, etc., identification is performed by stacking two color-forming layers that develop different colors and applying different amounts of heat. This is a method of obtaining two possible colors.
This method is suitable when the lower layer is of a black color system, because the color tone of the upper layer is obtained at a low temperature and the color tone of both layers is mixed at a high temperature. Since the decolorizing type does not use a decoloring agent, it has the advantages of excellent long-term storage stability of the recorded image and relatively inexpensive production, and it does not require extra heat to melt the decoloring agent Compared with the mold, it has an advantage that the high temperature color developing layer can be colored with low energy. However, the additive type two-color heat-sensitive recording material has a problem that if too much heat is applied at the time of low-temperature color development, the color development of the high-temperature color development layer partially mixes, resulting in color mixing, which makes it difficult to obtain clear low-temperature color development. Further, since two or more kinds of color-forming dyes having different color-developing color tones are used, there is a drawback that background fog is likely to occur.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a two-color heat-sensitive recording material in which a high-temperature color-developing layer and a high-temperature color-developing layer, which are different in color from each other, are sequentially laminated on a support. It is an object of the present invention to provide a two-color heat-sensitive recording material in which there is little mixing of high-temperature color tones and little background fog during printing.

[0008]

The present invention comprises a high-temperature color-forming layer containing a color-forming dye that develops black and a low-temperature color-forming layer that develops a color different from the high-temperature color-forming layer, which are sequentially laminated on a support. Additive type two-color thermosensitive recording material, JIS-K51
Oil absorption specified in 01 is 50ml / 100g or more 40
An intermediate layer containing 0 ml / 100 g or less of a pigment as a main component is provided between the high-temperature color-developing layer and the low-temperature color-developing layer, and 3-diethylamino-7-chlorofluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane,
3-cyclohexylamino-6-chlorofluoran, 3
-Diethylamino-6,8-dimethylfluorane, 7-
(N-ethyl-N-isoamylamino) -3-methyl-
1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3′-phthalide],
3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3- (4-diethylamino-
2-Methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-
A two-color heat-sensitive recording material containing at least one color-forming dye selected from (6′-dimethylamino) phthalide.

Further, the present invention is a two-color thermosensitive recording material in which each of the above-mentioned color forming dyes is contained in the low temperature color forming layer, and 3-di (n-butylamino) -6-methyl is used as the black color forming dye of the high temperature color forming layer. It exists in a two-color heat-sensitive recording material containing -7-anilinofluorane. Further, the present invention is a two-color thermosensitive recording material containing the above-mentioned color forming dyes in the low temperature color forming layer, wherein bis (3-allyl-4-) is used in the low temperature color forming layer.
It exists in a two-color heat-sensitive recording material containing at least one color-developing compound selected from hydroxyphenyl) sulfone and 4,4′-cyclohexylidenediphenol.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an intermediate layer mainly composed of a pigment having an oil absorption of 50 ml / 100 g or more and 400 ml / 100 g or less defined by JIS-K5101 is provided between a high temperature coloring layer and a low temperature coloring layer. Set up. Oil absorption is 50m
A pigment of 1/100 g or more is a material having a large porosity and an excellent heat insulating property. Therefore, by providing an intermediate layer mainly composed of a pigment having a large oil absorption property between the high temperature coloring layer and the low temperature coloring layer, it becomes difficult for heat energy during low temperature coloring to be transmitted to the high temperature coloring layer, and only the low temperature coloring layer is colored. You can get the color tone. However, the oil absorption is 400 ml
/ 100g is larger than the specific surface area of the pigment,
Since the scattering of light increases, the transparency decreases. Therefore, when a pigment having an oil absorption of more than 400 ml / 100 g is used as a main component in the intermediate layer, the high-temperature color-developing layer is hidden, resulting in a problem that the high-temperature color-developing black color becomes grayish. .

JIS-K5 which can be used for the intermediate layer of the present invention
Oil absorption specified in 101 is 50ml / 100g or more 4
Examples of the pigment of 00 ml / 100 g or less include light calcium carbonate, calcined clay, silica, calcium silicate, aluminum silicate and the like. Such a pigment is contained in an amount of 40% by weight or more, more preferably 60% by weight or more, based on the total solid content of the intermediate layer. If the content is less than 40% by weight, the desired effect on color separation cannot be obtained sufficiently. Of course, a pigment having an oil absorption of less than 50 ml / 100 g and a pigment having an oil absorption of more than 400 ml / 100 g may be used in combination. Further, an organic pigment made of polystyrene, urea, phenol, epoxy, melamine, guanamine, acrylic resin or the like can be used in combination. As the material other than the pigment forming the intermediate layer, the materials described in the structure of the color forming layer such as adhesives, waxes, metal soaps, ultraviolet absorbers, sensitizers and fluorescent dyes can be used.

In the additive type two-color thermosensitive recording material of the present invention, the low temperature color tone is various colors and the high temperature color tone is black, but a colorless electron-donating color developing dye is used for color development by heating. Coloring due to the reaction of the electron-accepting color-developing compound is utilized.

The electron-donating color-forming dyes used in the present invention include triallyl dyes, diphenylmethane dyes,
Thiazine-based dyes, spiro-based dyes, lactam-based dyes, fluoran-based dyes and the like are known. As a dye that gives a black color development, 3-di (n-butylamino) -6-methyl-
7-anilinofluorane, 3-di (n-pentylamino) -6-methyl-7-anilinofluorane, 3- (N
-Isoamyl-N-ethylamino) -6-methyl-7-
Anilinofluorane, 3- (N-n-hexyl-N-ethylamino) -6-methyl-7-anilinofluorane,
3- [N- (3-ethoxypropyl) -N-ethylamino) -6-methyl-7-anilinofluorane, 3-di (n-butylamino) -7- (2-chloroanilino) fluorane, 3- Diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-
7-anilinofluoran, 3- (N-cyclohexyl-
N-methylamino) -6-methyl-7-anilinofluorane and the like can be mentioned.

In the present invention, among the dyes that give a black color development, the inclusion of 3-di (n-butylamino) -6-methyl-7-anilinofluorane in the high temperature color development layer allows the color development at low temperature. A two-color recording material having excellent color separation properties and good background fog can be obtained. According to a study made by the present inventors, 3- (N-isoamyl-N-ethylamino) -6, which is widely used in black monochromatic heat-sensitive recording materials, has been investigated.
When 3-methyl-7-anilinofluorane or 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane is used in the high-temperature color-developing layer, background fogging easily occurs, and 3- Di (n-butylamino) -7-
With (2-chloroanilino) fluorane, there was no problem with background fog, but there was a problem that the black color development sensitivity was slow. Of course, 3-di (n-butylamino) -6-methyl-7-anilinofluorane may be used in combination with another electron-donating color forming dye.

In the present invention, by using an electron-donating color-forming dye that develops various colors in the low-temperature color-developing layer, each of red, orange, magenta, blue, and green has a low-temperature color-developing color tone. Although a recording material can be obtained, as a result of detailed study by the present inventors, it was found that there is a color forming dye which can be adapted according to each color tone. Dyes that give a red, magenta, or orange color are 3,
6-bis (diethylamino) fluorane-γ-anilinolactam, 3,6-bis (diethylamino) fluorane-γ- (p-nitro) anilinolactam, 3,6-bis (diethylamino) fluorane-γ- (o- (Chloro) anilinolactam, 3-dimethylamino-7-bromofluorane, 3-diethylaminofluorane, 3-diethylamino-6-methylfluorane, 3-diethylamino-
7-methylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylamino-6,8-dimethylfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-tert-butylfluorane, 3- (N-ethyl-N-tolylamino) -7
-Methylfluorane, 3- (N-ethyl-N-tolylamino) -7-ethylfluorane, 3- (N-ethyl-N)
-Isobutylamino) -6-methyl-7-chlorofluorane, 3- (N-ethyl-N-isoamylamino)-
7,8-Benzofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-di-n-butylamino-
6-methyl-7-bromofluorane, 3-di-n-butylamino-7,8-benzofluorane, 3-tolylamino-7-methylfluorane, 3-tolylamino-7-ethylfluorane, 3,3 '-Bis (1-n-butyl-2
-Methylindol-3-yl) phthalide, 3,3'-
Bis (1-ethyl-2-methylindol-3-yl)
Phthalide, 3,3′-bis (1-n-octyl-2-methylindol-3-yl) phthalide, 7- (N-ethyl-N-isoamylamino) -3-methyl-1-phenylspiro [(1 , 4-dihydrochromeno [2,3-c]
Pyrazole) -4,3′-phthalide], 7- (N-ethyl-N-isoamylamino) -3-methyl-1-p-methylphenylspiro [(1,4-dihydrochromeno [2,3-c] ] Pyrazole) -4,3'-phthalide],
7- (N-ethyl-Nn-hexylamino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide]
And so on.

The present inventors have conducted detailed research on the above compounds. As a result, it was found that there are few materials that can be adapted to the two-color heat-sensitive recording material of the present invention in terms of color development sensitivity and background fog. For example, as a dye that gives red color,
3-diethylaminofluorane, 3-diethylamino-
When 6-methylfluorane is used for this purpose, the background fog is large, and 3- (N-ethyl-N-tolylamino) -7-methylfluorane and 3- (N-ethyl-N-) are used.
With trilylamino) -7-ethylfluorane, the color separation is not good because the color development sensitivity is insufficient. A dye that gives an orange color is 3-diethylamino-7-t.
There is ert-butyl fluoran, but the background fog is large. Examples of dyes that give a reddish purple color are 3- (N-ethyl-N-isoamylamino) -7,8-benzofluorane and 3,3′-bis (1-n-octyl-2-methylindole-3- Ill) phthalides, etc., but the background fog is still big.

When the low-temperature color tone is red, in the present invention, 3-diethylamino-7-chlorofluorane and 3-diethylamino-6 are used as a color forming dye in the low temperature color forming layer.
At least one selected from -methyl-7-chlorofluorane. In order to obtain an orange color, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6,8-dimethylfluorane, 7- (N-ethyl-N-isoamylamino) is used as a color forming dye.
The low-temperature color developing layer contains at least one selected from -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide]. In order to obtain a reddish purple color, 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide is contained in the low temperature color forming layer as a color forming dye. Such a color-forming dye selected in the present invention is a material having high color-developing sensitivity and therefore excellent in color separation and also excellent in background fog. In the present invention, it goes without saying that other color forming dyes may be used in combination. Particularly in the case of red color development, it is rather desirable to mix and use dyes of red color development type having different tones for color tone correction, and 3-diethylamino-7-chlorofluorane or 3-diethylamino-6-methyl-7- Chlorofluorane with 3, 3 '
-Bis (1-n-butyl-2-methylindole-3-
)) Phthalide, or 3,3'-bis (1-ethyl-2-methylindol-3-yl) phthalide, etc., and a reddish color is strongly felt by adding a small amount of a coloring dye having a reddish purple color tone. It can be a color tone.

The color-forming dye that gives blue color is 3,
3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl)
-6-Dimethylaminophthalide, 3- (1-ethyl-2)
-Methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-)
Diethylaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-diethylaminophenyl) -4
-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-hexyloxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
Examples thereof include diphenylamino-6-diphenylaminofluorane.

According to a detailed study of the above compounds by the present inventors, among these blue-coloring dyes, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3 -(1-Ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) -phthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n The use of -hexyloxy-4-diethylaminophenyl) -4-azaphthalide in a two-color heat-sensitive recording material for this purpose was unsuitable because of large background fog. In the present invention, when the low-temperature color is blue, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide is used as the color-forming dye in the low-temperature color forming layer. When it is contained in the composition, it is possible to obtain a two-color heat-sensitive recording material which is excellent in color separation and has very little background fog. Of course, other color forming dyes can be used in combination.

The color-forming dye that gives a green color is 3
-(N-ethyl-Nn-hexylamino) -7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4 -Azaphthalide, 3-
(N-ethyl-Np-tolylamino) -7- (N-phenyl-N-methylamino) fluorane, 3- [p-
(P-anilinoanilino) anilino] -6-methyl-7
-Chlorofluorane, 3,6-bis (dimethylamino)
Examples thereof include fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide. Among the dyes that give a green color development, the present inventors have studied and found that among such dyes, 3-diethylamino-7-dibenzylaminofluorane, 3,3-bis (4-diethylamino-2).
-Ethoxyphenyl) -4-azaphthalide, 3- [p-
(P-anilinoanilino) anilino] -6-methyl-7
-Chlorofluorane did not give good results because of large background fog when it was applied to a two-color heat-sensitive recording material of additive type. In addition, 3- (N-ethyl-N-p-tolylamino) -7- (N-phenyl-N-methylamino) fluorane has a small background fog, but is deep-colored and difficult to distinguish from black, so two-color It has been found that it is not always compatible with thermal recording materials.

In the present invention, in the case where the low-temperature color development is green color development, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide is used as the color-forming dye in the low-temperature color development layer. When it is contained in the composition, it is possible to obtain a two-color heat-sensitive recording material which is excellent in color separation and has very little background fog. Of course, other color forming dyes can be used in combination. In the present invention, 3,6-dimethoxyfluorane, 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2-quinolyl) ethylene, or the like is appropriately blended as a dye that gives a yellowish color. You can also correct the color tone.

The electron-accepting color-developing compound used in the present invention has the property of liquefying or dissolving when the temperature rises and having the property of developing color by contact with the electron-donating color-forming dye. If it is good. A specific example of a typical electron-accepting color developing compound is 4-tert-
Butylphenol, 4-acetylphenol, 4-te
rt-octylphenol, 4,4′-sec-butylidene diphenol, 4-phenylphenol, 4,4 ′
-Dihydroxydiphenylmethane, 4,4'-isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis (3-methyl-6-te
rt-butylphenol), 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4- Hydroxybenzophenone,
Dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 4
-Tolyl hydroxybenzoic acid, chlorophenyl 4-hydroxybenzoate, phenolic compounds such as 4,4'-dihydroxydiphenyl ether, or benzoic acid,
p-tert-butylbenzoic acid, trichlorobenzoic acid,
Terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid,
Aromatic carboxylic acids such as 3,5-di-tert-butylsalicylic acid, and organic acidic substances such as salts of these phenolic compounds and aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum and calcium. Is mentioned.

Among these compounds, 4,4'-
Isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl -4-Hydroxyphenyl) sulfone is preferable in terms of sensitivity and whiteness. Also,
In order to obtain a heat-sensitive recording material that is hard to be erased by the contact with oil or plasticizer, 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, N-
(P-Toluenesulfonyl) -N'-phenylurea can be used as the color-developing compound. In the present invention, by containing at least one selected from bis (3-allyl-4-hydroxyphenyl) sulfone and 4,4′-cyclohexylidenediphenol in the low-temperature color-developing layer, two colors having excellent background fog can be obtained. It can be used as a thermal recording material.

In the low-temperature color-developing layer, the color-developing compound is usually used in a proportion of 100 to 700 parts by weight, preferably 150 to 400 parts by weight, based on 100 parts by weight of the color-forming dye. In order to suppress the background fog and obtain a two-color heat-sensitive recording material with high whiteness, it is more desirable to use the same color developing compound for the high temperature color forming layer and the low temperature color forming layer. However, the color-developing compound may be contained in at least the low-temperature color-developing layer, and is not necessarily contained in the high-temperature color-developing layer. Further, such a color-developing compound can be used in the intermediate layer.

In the present invention, a compound may be added mainly for improving the preservability after printing and recording. For example, 1,1,3-tris (2-methyl-4-hydroxy-5)
-Cyclohexylphenyl) butane, 1,1-bis (4
-Hydroxyphenyl) -1-phenylethane, 1,
1,3-tris (2-methyl-4-hydroxy-5-t
ert-Butylphenyl) butane, 1,1-bis (2-
Methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4 ′-[1,4-phenylenebis (1
-Methylethylidene)] bisphenol, 4,4'-
[1,3-Phenylenebis (1-methylethylidene)]
Phenolic compounds such as bisphenol and 4-
Benzyloxyphenyl-4 '-(2-methyl-2,3
-Epoxypropyloxy) phenyl sulfone, 4-
(2-Methyl-1,2-epoxyethyl) diphenyl sulfone, 4- (2-ethyl-1,2-epoxyethyl)
Epoxy compounds such as diphenyl sulfone, 1,3,5-
Tris (2,6-dimethylbenzyl-3-hydroxy-
4-tert-butyl) isocyanuric acid and the like. Of course, it is not limited to these, and two or more kinds of compounds can be used in combination as required.

In order to improve the sensitivity of the heat-sensitive recording material, the high temperature color forming layer, the low temperature color forming layer and the intermediate layer may contain a heat fusible substance as a sensitizer. Examples of the sensitizer include parabenzyl biphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, di-o-chlorobenzyl adipate,
1,2-di (3-methylphenoxy) ethane, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, 1,2-bis (3,4-dimethylphenyl) ethane and the like can be used. In particular, when di-p-methylbenzyl oxalate and di-p-chlorobenzyl oxalate are used in combination, sensitization with less fog can be obtained, so that favorable results can be obtained.

The color-developing dye, the color-developing compound, the compound for improving the storage stability and the sensitizer used in the present invention are various wet methods such as a sand grinder, an attritor, a ball mill and a cobo mill using water as a dispersion medium. Disperse and disperse with a water-soluble synthetic polymer compound such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, and styrene-maleic anhydride copolymer salt and their derivatives by a pulverizer, as well as a surfactant. After being made into a liquid, it is used for the preparation of paints for the high temperature color forming layer and the low temperature color forming layer.

In the present invention, various inorganic and organic pigments usually used in heat-sensitive recording materials can be used. Examples of such pigments include inorganic pigments such as kaolin, calcined kaolin, talc, clay, silica, wax, diatomaceous earth, light calcium carbonate, heavy calcium carbonate, aluminum hydroxide, magnesium hydroxide, titanium oxide and barium carbonate. Examples of the organic pigment include polystyrene, urea, phenol, epoxy, melamine, guanamine, and acrylic resin.

In the present invention, other materials for forming the high temperature coloring layer and the low temperature coloring layer include adhesives, waxes, metal soaps, and if necessary, ultraviolet absorbers and fluorescent dyes. Examples of the adhesive include polyvinyl alcohol and its derivatives, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, and acrylamide-acrylic acid ester copolymer. Coalescence, acrylamide-acrylic acid ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin and water-soluble polymers such as their derivatives, Polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester,
Examples thereof include emulsions of vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer and the like, styrene-butadiene copolymer, latex of styrene-butadiene-acrylic copolymer and the like.

As the wax, paraffin wax,
In addition to carnauba wax, microcrystalline wax, polyolefin wax, polyethylene wax, higher fatty acid amides such as stearic acid amide, ethylenebisstearic acid amide, higher fatty acid ester and derivatives thereof can be mentioned. In particular, a methylolated fatty acid amide can obtain a sensitizing effect without deteriorating the background fog. As the metal soap, higher fatty acid polyvalent metal salts, namely zinc stearate, aluminum stearate,
Examples thereof include calcium stearate and zinc oleate. In addition, various additives such as an oil repellent, a defoaming agent and a viscosity modifier may be added as long as the effects of the present invention are not impaired.

The support material used in the present invention is not particularly limited and includes, for example, high-quality paper (acidic paper, neutral paper), medium-quality paper, coated paper, art paper, cast coated paper, glassine paper, resin. In addition to laminated paper, polyolefin-based synthetic paper, synthetic fiber paper, non-woven fabric, synthetic resin film and the like, various transparent supports and the like can be appropriately used.

In the present invention, the two-color heat-sensitive recording material can be further processed to increase its added value to give a heat-sensitive recording material having higher functions. For example,
Adhesive paper, rewetting adhesive, delayed tack type adhesive, etc. can be processed on the back side to make adhesive paper, rewetting adhesive paper, delayed tack paper, or magnetic recording on the back side by magnetic processing. It can be a material. In particular, a two-color heat-sensitive label or a two-color heat-sensitive magnetic ticket that has been subjected to adhesive processing or magnetic processing is useful. Further, the back side can be used to have a function as a thermal transfer paper, an inkjet paper, a carbonless paper, an electrostatic recording paper, and a xerographic paper, so that the recording paper can be recorded on both sides. Of course, a double-sided heat-sensitive recording material can also be used. By using two or more types of two-color thermal recording materials of the present invention having different low-temperature color tones at the same time, it is possible to greatly expand the applications that can be used, such as color coding of files, color coding of destinations of delivered products, and color classification of receipts and journals. be able to.
Further, by applying the present invention, it is also possible to obtain a thermosensitive recording material of three or more colors by providing a color forming layer having a different color tone from the low temperature color tone.

In the present invention, a protective layer may be provided on the low temperature coloring layer and an undercoat layer may be provided below the high temperature coloring layer.
For these layers, a protective layer and an undercoat layer which are conventionally used in known heat-sensitive recording materials can be applied. Both the protective layer and the undercoat layer are mainly composed of pigments and adhesives.
In particular, it is desirable to add a lubricant such as polyolefin wax or zinc stearate to the protective layer for the purpose of preventing sticking to the thermal head, and it is also possible to have a constitution of two or more layers. UV curable resin, E
B-cured resin can be used as a protective layer, and U
It is also possible to print with V ink, flexo ink, etc. A linerless adhesive label can be obtained by using a release agent such as silicone for the protective layer.

As a method for forming each layer, any known coating method such as an air knife method, a blade method, a gravure method, a roll coater method, a spray method, a dip method, a bar method and an extrusion method can be used. good.
The high temperature color developing layer coating material, the intermediate layer coating material and the low temperature color developing layer coating material are respectively applied to one surface of the support so as to be 1 to 10 g / m ² (dry), whereby a color forming layer is formed. Further, a back layer may be provided for suppressing the penetration of oil or plasticizer from the back surface and controlling curl. In addition, smoothing the coating layer using a known smoothing method such as a super calendar or a soft calendar is effective in increasing the color developing sensitivity.

[0035]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.
Unless indicated otherwise, parts and% refer to parts by weight and% by weight, respectively. (1) Preparation of color-developing dye, color-developing compound and sensitizer dispersion Black color- developing dye A 3-di (n-butylamino) -6-methyl-7-anilinofluorane B 3- (N- Isoamyl-N-ethylamino) -6-
Methyl-7-anilinofluorane red coloring dye A 3-diethylamino-7-chlorofluorane B 3-diethylamino-6-methyl-7-chlorofluorane C 3-diethylamino-6-methylfluorane D 3- ( N-Ethyl-N-tolylamino) -7-methylfluorane orange color forming dye A 3-cyclohexylamino-6-chlorofluorane B 3-diethylamino-6,8-dimethylfluorane C 7- (N-ethyl- N-isoamylamino) -3-
Methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3′-phthalide] D 3-diethylamino-7-tert-butylfluorane

Red-purple color-forming dye A 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide B 3- (N-ethyl-N-isoamylamino) -7,
8-benzofluorane blue color-forming dye A 3- (4-diethylamino-2-methylphenyl)
-3- (4-Dimethylaminophenyl) -6-dimethylaminophthalide B3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide green color forming dye A 3,6-bis (dimethylamino) fluorene-9-
Spiro-3 '-(6'-dimethylamino) phthalide B 3-diethylamino-7-dibenzylaminofluorane

Color- developing compound A Bis (3-allyl-4-hydroxyphenyl) sulfone B 4,4'-cyclohexylidene diphenol C 4,4'-isopropylidene diphenol sensitizer A Oxalic acid di-p- Methylbenzyl B Di-p-chlorobenzyl oxalate The above color-forming dye, color-developing compound, and sensitizer were mixed in the following blending ratio, and these compositions were mixed in a vertical sand mill (IMEX Co., Ltd., Sand Grinder). ) Were separately dispersed so that the average particle diameter was 1 μm. Component Amount (parts by weight) Color-forming dye, color-developing compound, sensitizer 40 Polyvinyl alcohol 10% liquid 40 (Polymerization degree 500, saponification degree 90%) Water 20

(2) Preparation of pigment dispersion Pigment A Silica (Mizukasil P527, oil absorption 190 ml /
100 g, manufactured by Mizusawa Chemical Industry Co., Ltd. B Aluminum hydroxide (Hijilite H42, oil absorption 36 ml / 100 g, manufactured by Showa Denko KK) C Light calcium carbonate (Unibar 70, oil absorption 52 m)
1/100 g, manufactured by Shiraishi Industry Co., Ltd. The above pigments were mixed in the following mixing ratios, and these compositions were dispersed by a Cowles disperser. Component Amount (parts by weight) Each pigment 60 Sodium polyacrylate 0.7% solution 40 In addition, polyvinyl alcohol having a solid content concentration of 10% as an adhesive A liquid (NM11Q, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.),
A crosslinked polystyrene resin (Grossdale 104S, manufactured by Mitsui Toatsu Chemicals, Inc.) having a solid content concentration of 47% was prepared as a plastic pigment A liquid.

Formation of High-Temperature Coloring Layer (Black Coloring Layer) These dispersions and adhesives are used in Examples and Comparative Examples whose weight ratios after drying are shown in Table 1, Table 2, Table 3, Table 4 and Table 5. The components were mixed in a corresponding manner to obtain a high temperature color forming layer coating liquid. 5.0 g / m ² (dry) of this coating liquid was applied onto a high-quality paper (neutral paper) having a basis weight of 60 g / m ² using a Meyer bar to form a high-temperature color-developing layer. Formation of Intermediate Layer These dispersions and adhesives were mixed so that the weight ratio after drying corresponded to the examples and comparative examples of Table 1, Table 2, Table 3, Table 4, and Table 5, and the intermediate layer was coated. 2.5 g / m ² (dry) using a Mayer bar on the high-temperature color development layer previously formed as a working solution
It was applied to form an intermediate layer. Formation of Low-Temperature Coloring Layer Mixing was performed so that the weight ratio after drying corresponded to the examples and comparative examples in Table 1, Table 2, Table 3, Table 4, and Table 5 to prepare a low-temperature coloring layer coating solution. A 3.0 g / m ² (dry) coating of this coating liquid was performed on the high-temperature color-developing layer previously formed using a Meyer bar to form a low-temperature color-developing layer. Then, using a super calendar, the Beck's smoothness of the heat-sensitive recording surface (JIS-P811
9) was smoothed for 50 to 150 seconds to prepare a two-color heat-sensitive recording material.

The two-color heat-sensitive recording material obtained by the above operation was tested. Recording was performed using a commercially available heat-sensitive facsimile HIFAX-45 modified for the test, solid printing of 256 lines was performed with 1 line recording time of 5 msec, sub-scanning line density of 8 lines / mm, and applied energy per dot of 0.4 mJ. A low-temperature color tone was obtained in low-temperature printing. Further, the recording time per line is 5 msec, the sub-scanning linear density is 8 lines / mm, and the applied energy per dot is 1.
Solid printing of 256 lines was performed at 5 mJ, and black color development was obtained in high temperature printing. With respect to the low-temperature color-developed product and the black-colored product thus obtained, the color tone was visually evaluated according to the following evaluation criteria. Color tone of low temperature color development area ○: Vivid color development ×: Muddy color with black color or low density color development Color tone of black color development area ○: Clear and high density black color development ×: Black color development with low temperature color development Alternatively, in order to evaluate the background fog, the obtained two-color thermosensitive recording material was allowed to stand in an environment of 40 ° C. and 90% RH for 24 hours, and then the whiteness (Hunter whiteness, JIS P812
3) was measured. When the whiteness is 75 or more, the contrast with the image is excellent, and when it is 70 or more, there is no practical problem. The results thus obtained are shown in Table 1, Table 2, Table 3, Table 4, and Table 5.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

As is apparent from the results of Table 1, Table 2, Table 3, Table 4, and Table 5, according to the present invention, clear low-temperature color tone without black tint is obtained in low-temperature printing, and high-temperature printing is possible. It has become possible to produce a two-color heat-sensitive recording material which has a high density of black color with no color development at low temperature and is extremely excellent in color separation.

Claims (3)

[Claims] 1. A color-added, two-color thermosensitive recording material comprising a support, on which a high-temperature color-forming layer containing a color-forming dye that develops black and a low-temperature color-forming layer that develops a color different from the high-temperature color-developing layer are sequentially laminated. The oil absorption amount specified in JIS-K5101 is 5
An intermediate layer containing 0 ml / 100 g or more and 400 ml / 100 g or less of a pigment as a main component is provided between the high temperature coloring layer and the low temperature coloring layer, and 3-diethylamino-7 is provided in the low temperature coloring layer.
-Chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-cyclohexylamino-
6-chlorofluorane, 3-diethylamino-6,8-
Dimethylfluorane, 7- (N-ethyl-N-isoamylamino) -3-methyl-1-phenylspiro [(1,
4-dihydrochromeno [2,3-c] pyrazole)-
4,3′-phthalide], 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3-
(4-Diethylamino-2-methylphenyl) -3-
At least one color-forming property selected from (4-dimethylaminophenyl) -6-dimethylaminophthalide and 3,6-bis (dimethylamino) fluorene-9-spiro-3 ′-(6′-dimethylamino) phthalide A two-color heat-sensitive recording material containing a dye. 2. A black color forming dye for a high temperature color forming layer,
The two-color heat-sensitive recording material according to claim 1, which contains di (n-butylamino) -6-methyl-7-anilinofluorane. 3. The low-temperature color-developing layer contains at least one color-developing compound selected from bis (3-allyl-4-hydroxyphenyl) sulfone and 4,4′-cyclohexylidenediphenol. The two-color thermosensitive recording material according to claim 1.