JP2002254824A - Multicolor heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a color separation of a low-temperature printed part from a high-temperature printed part with a good chemical resistance and simultaneously a color bleeding of the high-temperature printed part in an additive color type multicolor heat-sensitive recording material of a single layer of a color developing layer for color developing in a different color tones from each other at low and high temperatures according to a difference of a heating condition. SOLUTION: A low-temperature color developing dye precursor and a high- temperature color developing dye precursor made of one or more types of dye precursors are covered with a color developing regulating layer having a different color developing sensitivity obtained by polymerizing a vinyl monomer for use. Specially, one type of the high-temperature precursor is used as a dye precursor of a complementary color of the low-temperature precursor, and hence the 'color bleeding' is improved. Further, the low-temperature and high-temperature precursors are dissolved and melted to amorphous dye precursors, then covered with the color developing regulating layer having different color developing sensitivity for use. Thus, an image having good image preservability (chemical resistance) at high sensitivity for both low-temperature and high-temperature printing and no 'color bleeding' is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor heat-sensitive recording material which develops different colors at low and high temperatures depending on differences in heating conditions such as the color development temperature. More specifically, the present invention relates to a multicolor heat-sensitive recording material having good color separation between a low-temperature printing portion and a high-temperature printing portion, and excellent chemical resistance and little color bleeding.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support provided with a thermosensitive recording layer mainly comprising an electron-donating usually colorless or pale-color dye precursor and an electron-accepting developer. By heating with a head, a hot pen, a laser beam, etc., the dye precursor and the electron-accepting color developer react instantaneously to produce a color image, and the recording device is simple and easy to maintain, and noise is reduced. Due to its advantages such as no occurrence, it is used in a wide range of fields such as measurement recorders, facsimile machines, printers, computer terminals, POS label machines, and ticket vending machines.

With the diversification of uses of such heat-sensitive recording materials, multi-color heat-sensitive recording materials that develop different colors at low and high temperatures due to differences in heating conditions are desired. With good color separation, ie
It is strongly desired that the high-temperature printing portion does not cause color mixing due to low-temperature colors, does not cause low-temperature color bleeding around high-temperature printing characters, and has high sensitivity, no background fog, and good image storability. ing.

[0004] Multicolor thermosensitive recording materials include those having a multi-layer structure in which a high-temperature coloring layer and a low-temperature coloring layer are sequentially laminated on a support and separated into separate layers, and a material which develops color at high or low temperature. A typical example is one in which at least one of them has a single-layer structure separated by microcapsules or the like.

Japanese Patent Application Laid-Open No. 54-097048 discloses a multi-layered structure in which dye precursors that develop colors different from each other are classified into a high-temperature coloring layer and a low-temperature coloring layer. There is a method of obtaining a color mixture of a low-temperature hue and a high-temperature hue. In this method, the color separation is good because the high-temperature coloring layer and the low-temperature coloring layer are separated, but the sensitivity is low because the high-temperature coloring layer is in the lower layer. For example, a high-temperature color (for example, a black-based color) is partially developed during printing, so that color mixing cannot be avoided and the color becomes blackish red, and color separation is still insufficient. In order to improve this color separation, JP-A-55-139470 and JP-A-57-178791 disclose a dye precursor that forms colors different from each other between a high-temperature coloring layer and a low-temperature coloring layer. A decoloring type method has been proposed in which layers are separated via a colorant layer and, at the time of high-temperature printing following low-temperature printing, high-temperature colors are printed while decolorizing low-temperature colors. In this method, low-temperature colors are erased during high-temperature coloring, so color separation is very good.However, the presence of the decoloring agent adjacent to the high-temperature and low-temperature coloring layers means that images can be stored for a long period of time. There is a drawback that the sex remains uneasy and the production cost is high.

[0006] One type of the color-forming layer having a single-layer structure includes a microcapsule for performing low-temperature and high-temperature printing color separation. Japanese Patent Application Laid-Open No. 60-242093 discloses a glass transition temperature of the microcapsule wall of polyurethane or the like. Japanese Patent Application Laid-Open No. 8-282115 discloses a method in which two or more different types of microcapsules contain color-forming components each of which develops a different hue. There is a method of encapsulating at least one kind of the dye precursor in a microcapsule. In these methods, the color separation is good because the dye precursor is isolated from each other by the capsule membrane, but an oily liquid in which the dye precursor is dissolved or emulsified is included in the microcapsules, and the pressure and the handling during handling are reduced. There is a disadvantage that the capsules are broken by friction and coloring of the background occurs.

On the other hand, the present applicant has previously filed Japanese Patent Application Laid-Open No. Hei 11-301118 for a method of providing a color control layer around a dye precursor. According to this method, at least one or more of two or more dye precursors which form colors different from each other are covered with a color control layer polymerized with a compound having an unsaturated carbon bond, and further, image preservability (chemical resistance) is good. A multicolor heat-sensitive recording material is obtained by a combination with a specific electron-accepting developer.
According to this method, the coloring sensitivity is shifted to the high-temperature side by covering the dye precursor particles on the high-temperature coloring side with the coloring control layer,
The dye precursor on the low-temperature coloring side is used in the form of dispersed particles to perform color separation of high-temperature coloring and low-temperature coloring, and to improve image storability using an electron-accepting developer with strong acid strength. I have.
In this method, color separation is good, but the phenomenon of so-called “color bleeding” still occurs in which the periphery of the character bleeds with a low-temperature color during high-temperature printing. Further, since the low-temperature coloring dye precursor is in the form of dispersed particles, the low-temperature color image preservability (chemical resistance) was insufficient. The present inventor has worked on improving the "color bleeding" and the image storability (chemical resistance) of low-temperature colors, and has arrived at the present invention.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a multicolor heat-sensitive recording material having a single-layered color-forming layer which develops different colors at low and high temperatures depending on the heating conditions. Is good in color separation and chemical resistance, and at the same time, improves the phenomenon of so-called "color bleeding" in which the periphery of a character bleeds with a low-temperature color during high-temperature printing.

[0009]

The object of the present invention is to provide an electron-donating, usually colorless or light-color, low-temperature coloring dye precursor and high-temperature coloring dye precursor on a support, and the coloring of the dye precursor upon heating. Provided with a heat-sensitive recording layer containing an electron-accepting developer, in a multicolor heat-sensitive recording material that develops different colors depending on the temperature difference, the low-temperature coloring dye precursor and the high-temperature coloring dye precursor, This is achieved by coating and using a color control layer having a different color sensitivity obtained by polymerizing a vinyl monomer. In particular, the dye precursor for low-temperature coloring and the dye precursor for high-temperature coloring consist of one or more dye precursors, and one of the dye precursors for high-temperature coloring is a complementary color of the dye precursor for low-temperature coloring. The body improves "color bleeding".
Furthermore, the low-temperature coloring dye precursor and the high-temperature coloring dye precursor are each melted and melted to form an amorphous dye precursor, and then used by being coated with a coloring control layer having a different coloring sensitivity. Both low-temperature printing and high-temperature printing provide images with high sensitivity and good image storability (chemical resistance) without "color bleeding". Here, the coloring control layers having different coloring sensitivity can be produced by changing the mixing ratio of the monofunctional vinyl monomer and the bifunctional or higher functional vinyl monomer.

[0010]

DETAILED DESCRIPTION OF THE INVENTION As the dye precursor and the electron-accepting color developer used in the present invention, those conventionally known in the field of heat-sensitive recording paper are used in various combinations. The dye precursor for low-temperature color formation is obtained by mixing one or more dye precursors alone, or by mixing or dissolving and melting the mixture, and then pulverizing to polymerize a vinyl monomer on the surface of the particles. Then, a color control layer obtained by the above method is provided and used for the heat-sensitive recording layer. Similarly, one of the high-temperature coloring dye precursors,
One or more kinds of low-temperature color different from the hue, preferably a low-color complementary dye precursor alone, or mixed, or after the mixture is melted and melted, then pulverized and the surface of the particles A color-developing layer obtained by polymerizing a vinyl monomer is provided so as to have a lower sensitivity than in the case of low-temperature color, and is used for the heat-sensitive recording layer.

The low-temperature coloring dye precursors include reddish
One or more dye precursors that develop yellowish or greenish to blueish colors are used in appropriate combination, but the color-added multicolor thermosensitive recording material tends to have a dark color due to color mixing at high temperatures. Therefore, at low temperatures, light reddish to yellowish colors are preferably used. On the other hand, the color tone of the high-temperature coloring dye precursor is appropriately determined according to the mixed color tone with the intended low-temperature color,
The color tone is often black by using one or more dye precursors in combination. When the color tone of the low-temperature color is reddish, a dye precursor that develops a high-temperature color and a complementary green color is used.When the color tone of the low-temperature color is a bluish color, the color is a high-temperature color. The use of a dye precursor that develops a yellowish color that is a complementary color thereof is preferable because color mixing at high temperatures approaches black and color bleeding with the naked eye is reduced.

[0012] When two or more dye precursors are used in combination, two or more dye precursors tend to have a higher color-forming sensitivity and a higher chemical resistance of a color image. This tendency is particularly remarkable when the dye precursor is melted and melted to be amorphous. The melt-melted dye precursor becomes amorphous and solidifies from an amorphous state to a microcrystalline state, depending on the method of solidification after melting and the storage state. Therefore, when the melt of the dye precursor itself is pulverized and used as a heat-sensitive recording material, the coloring sensitivity is high, and the image preservability (chemical resistance) is extremely excellent, but on the other hand, the background fog is also reduced. It is very large and is difficult to use as it is as a thermal recording material. In the present invention, the background color fog can be improved while the color development sensitivity is kept almost by the action of the color development control layer.
In the molten melt of more than one kind of dye precursor, since the mixed color can be faithfully obtained depending on the ratio of the dye precursor to be used, it becomes possible to set the color tone to a desired color, so this amorphous dye The precursor is one that is used effectively.

Here, in order to obtain a dispersion of the dye precursor, in the case of a crystalline dye precursor, the powder of the dye precursor is used as it is, by a conventional sand mill, ball mill, or pressure emulsification method. The particle size is 0.1
μm to 2 μm, preferably 0.5 μm to 1.2
Disperse particles having a size of not more than μm.

On the other hand, in order to obtain a dispersion of an amorphous dye precursor, (1) one or more of the dye precursors are heated and melted, cooled and coarsely pulverized to obtain a dispersion in the same manner as a crystalline dye precursor. And finely dispersing using a dispersing device. (2) A method in which one or more dye precursors are heated and melted, and then emulsified and dispersed in warm water containing a protective colloid, a surfactant and the like. (3) After dissolving all the dye precursor in a solvent that dissolves, after emulsifying and dispersing this solution in a non-solvent of the dye precursor, a method of heating and distilling off the solvent is used, dispersed particles or emulsified particles The size of.
1 μm or more and 2 μm or less, preferably 0.5 μm or more.
It is adjusted to be 2 μm or less. These dispersions or emulsions are then transferred to a step of coating the color control layer.

Here, for low-temperature coloring used in the present invention,
Specific examples of the dye precursor for high-temperature coloring include red, yellow, blue, green, and black colors, but are not limited thereto.

As the red dye precursor, 3,3-bis (1-n-butyl-2-methylindol-3-yl)
Phthalide, 3,3-bis (1-n-butyl-2-methylindol-3-yl) tetrachlorophthalide, 3,3
-Bis (1-n-butylindol-3-yl) phthalide, 3,3-bis (1-n-pentyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-
Hexyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-octyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-methyl-2-methylindole) -3-yl) phthalide, 3,
3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-propyl-2-methylindol-3-yl) phthalide, 3,3-bis (2
Methylindol-3-yl) phthalide, rhodamine B
-Anilinolactam, rhodamine B- (o-chloroanilino) lactam, rhodamine B- (p-nitroanilino) lactam, 3-diethylamino-5-methyl-7-
Dibenzylaminofluoran, 3-diethylamino-6
-Methyl-7-chlorofluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-6
Methylfluoran, 3-diethylamino-6-methyl-
7-chloro-8-benzylfluoran, 3-diethylamino-6,7-dimethylfluoran, 3-diethylamino-6,8-dimethylfluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7- Methoxyfluoran, 3-diethylamino-7- (N-acetyl-N-methyl) aminofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-
7-methylethoxyfluoran, 3-diethylamino-
7-p-methylphenylfluoran, 3-diethylamino-7,8-benzofluoran, 3-diethylaminobenzo [a] fluoran, 3-diethylaminobenzo [c] fluoran, 3-dimethylamino-7-methoxyfluoran, 3-dimethylamino-6-methyl-7-chlorofluorane, 3-dimethylamino-7-methylfluorane, 3-dimethylamino-7-chlorofluorane,
3- (N-ethyl-p-toluidino) -7-methylfluoran, 3- (N-ethyl-N-isoamyl) amino-
6-methyl-7-chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-7,8-benzofluoran, 3- (N-ethyl-N-isoamyl) amino-7-
Methylfluoran, 3- (N-ethyl-Nn-octyl) amino-6-methyl-7-chlorofluoran, 3-
(N-ethyl-NN-octyl) amino-7,8-benzofluoran, 3- (N-ethyl-Nn-octyl) amino-7-methylfluoran, 3- (N-ethyl-N -N-octyl) amino-7-chlorofluoran,
3- (N-ethyl-N-4-methylphenyl) amino-
7,8-benzofluoran, 3- (N-ethyl-N-4
-Methylphenyl) amino-7-methylfluoran, 3
-(N-isopentyl-N-ethyl) amino-7,8-
Benzofluorane, 3- (N-ethoxyethyl-N-ethyl) amino-7,8-benzofluoran, 3- (N-
(Ethoxyethyl-N-ethyl) amino-7-chlorofluorane, 3-n-dibutylamino-6-methyl-7-chlorofluorane, 3-n-dibutylamino-7,8-benzofluoran, 3-n -Dibutylamino-7-chlorofluorane, 3-n-dibutylamino-7-methylfluoran, 3-diallylamino-7,8-benzofluoran, 3-diallylamino-7-chlorofluoran, 3-
Di-n-butylamino-6-methyl-7-bromofluorane, 3-cyclohexylamino-6-chlorofluoran, 3-pyrrolidylamino-7-methylfluoran, 3
-Ethylamino-7-methylfluoran, 3-diethylamino-benzo [a] fluoran, 3-N-ethyl-N
-Isoamylamino-benzo [a] fluoran, 3-N
-Ethyl-N-p-methylphenylamino-7-methylfluoran, 3-dibutylamino-6-methyl-7-bromofluorane, 3,6-bis (diethylaminofluoran) -γ- (4′-nitro ) Anilinolactam.

Examples of the yellow dye precursor include 3,6-dimethoxyfluoran, 3-cyclohexylamino-6-chlorofluoran, 2,6-diphenyl-4- (4-dimethylaminophenyl) -pyridine, , 2-bis (4-
(2- (4-diethylaminophenyl) quinazolyl) oxyphenyl) propane, 4-chloro-N- (4- (N
-(4-methylbenzyl) -N-methylamino) benzylidene) aniline, 1- (2-quinolyl) -2- (3-
Methoxy-4-dodecyloxyphenyl) ethene, 1-
(4-n-dodecyloxy-3-methoxyphenyl)-
2- (2-quinolyl) ethylene.

The blue dye precursor includes 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-methylindole -3-yl) -3- (2-ethoxy-4-aminophenyl) -4
-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-methylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole- 3-yl) -3- (2-ethoxy-4-ethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dimethyl) Aminophenyl) -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-ethoxy-4-dipropylaminophenyl)-
4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dibutylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole -3-yl) -3- (2-
Ethoxy-4-dipentylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-
3-yl) -3- (2-ethoxy-4-dihexylaminophenyl) -4-azaphthalide, 3- (1-ethyl-
2-methylindol-3-yl) -3- (2-ethoxy-4-dihydroxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-
Yl) -3- (2-ethoxy-4-dichloroaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4
-Dibromoaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-diallylaminophenyl) -4
-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dihydroxyaminophenyl) -4-azaphthalide, 3- (1-
Ethyl-2-methylindol-3-yl) -3- (2
-Ethoxy-4-dimethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-dicyclohexylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) ) -3- (2-Ethoxy-4-dimethylethoxyaminophenyl) -4-azaphthalide, 3- (1-
Ethyl-2-methylindol-3-yl) -3- (2
-Ethoxy-4-diethylethoxyaminophenyl)-
4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylbutoxyaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-dimethylcyclohexaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-
Methylindol-3-yl) -3- (2-ethoxy-
4-dimethoxycyclohexylaminophenyl) -4-
Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-pyrrolidylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole- 3-yl) -3- (3-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-
Yl) -3- (2,3-diethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-
2-methylindol-3-yl) -3- (4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-
Chloro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-
Yl) -3- (3-Chloro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-bromo-4-diethylaminophenyl)- 4-azaphthalide, 3- (1
-Ethyl-2-methylindol-3-yl) -3-
(3-bromo-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethyl-4-diethylaminophenyl) -4-azaphthalide, -(1-ethyl-2
-Methylindol-3-yl) -3- (2-propyl-4-diethylaminophenyl) -4-azaphthalide;
3- (1-ethyl-2-methylindol-3-yl)
-3- (3-Methyl-4-diethylaminophenyl)-
4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-nitro-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole- 3-yl) -3- (2-allyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-hydroxy-4-diethylaminophenyl ) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-cyano-4-
Diethylaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-methylindol-3-yl) -3
-(2-cyclohexylethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2
-Methylindol-3-yl) -3- (2-methylethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-
Yl) -3- (2-cyclohexylethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (2-ethylindol-3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-chloroindol-3-yl) -3
-(2-ethoxy-4-diethylaminophenyl) -4
-Azaphthalide, 3- (1-ethyl-2-bromoindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-ethylindole-3 -Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-propylindole-3
-Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-
Methoxyindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide;
3- (1-ethyl-2-ethoxyindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-phenylindol-3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-diethylaminophenyl) -7
-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1
-Ethyl-4,5,6,7-tetrachloro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1
-Ethyl-4-nitro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methoxy-2-methylindole- 3-yl) -3- (2-
Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-4-methylamino-2-methylindol-3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
(1-Ethyl-4-methyl-2-methylindole-3
-Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide , 3- (1-Chloro-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-bromo-2-methylindole-3-
Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindol-3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
(1-methyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-diethylaminophenyl) -7
-Azaphthalide, 3- (1-propyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-butyl-2-methylindole-3 -Yl) -3- (2-
Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-butyl-2-indol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1- Pentyl-2-methylindol-3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
(1-hexyl-2-methylindol-3-yl)-
3- (2-ethoxy-4-diethylaminophenyl)-
4-azaphthalide, 3- (1-hexyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-
Octyl-2-methylindol-3-yl) -3-
(2-ethoxy-4-diethylaminophenyl) -4-
Azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl-2-methylindole-3- Il) -3- (2-
Ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1-nonyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-methoxy-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethoxy-2-methylindole-3
-Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-phenyl-2)
-Methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide;
3- (1-pentyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-heptyl-2-methylindol-3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -7-azaphthalide, 3-
(1-Nonyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-diethylaminophenyl) -7
-Azaphthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-dimethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethyl Aminophthalide,
3- (1-ethyl-2-methylindol-3-yl)
-3- (4-Diethylamino-2-n-hexyloxyphenyl) -4-azaphthalide.

Examples of green dye precursors include 3- (N-ethyl-NN-hexyl) amino-7-anilinofluoran and 3- (N-ethyl-N-p-tolyl) amino-7.
-(N-phenyl-N-methyl) aminofluoran, 3
-(N-ethyl-NN-propyl) amino-7-dibenzylaminofluoran, 3- (N-ethyl-NN-
Propyl) amino-6-chloro-7-dibenzylaminofluoran, 3- (N-ethyl-N-4-methylphenyl) amino-7- (N-methyl-N-phenyl) aminofluoran, 3- ( N-ethyl-4-methylphenyl)
Amino-7-dibenzylaminofluoran, 3- (N-
Ethyl-4-methylphenyl) amino-6-methyl-7
-Dibenzylaminofluoran, 3- (N-ethyl-4
-Methylphenyl) amino-6-methyl-7- (N-methyl-benzyl) aminofluoran, 3- (N-methyl-Nn-hexyl) amino-7-anilinofluoran, 3- (N- Propyl-Nn-hexyl) amino-
7-anilinofluoran, 3- (N-ethoxy-Nn
-Hexyl) amino-7-anilinofluoran, 3-
(Nn-pentyl-N-allyl) amino-6-methyl-7-anilinofluoran, 3- (Nn-pentyl-
N-allyl) amino-7-anilinofluoran, 3-n
-Dibutylamino-6-chloro-7- (2-chloroanilino) fluoran, 3-n-dibutylamino-6-methyl-7- (2-chloroanilino) fluoran, 3-n-
Dibutylamino-6-methyl-7- (2-fluoroanilino) fluoran, 3-n-dibutylamino-7- (2
-Chloroanilino) fluoran, 3-n-dibutylamino-7- (2-chlorobenzylanilino) fluoran,
3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3-diethylamino -6-methyl-7-benzylamino-fluoran, 3-diethylamino-6-methyl-7-dibenzylaminofluoran, 3
-Diethylamino-6-methyl-7-n-octylaminofluoran, 3-diethylamino-6-methyl-7-
(N-cyclohexyl-N-benzylamino) fluoran, 3-diethylamino-6-methyl-7- (2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7- (2-trifluoromethylanilino) fluoran, 3-diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluoran, 3-diethylamino-6-methyl-7- (2-ethoxyanilino) fluoran, 3-diethylamino-6-methyl-7- (4
-Ethoxyanilino) fluoran, 3-diethylamino-6-chloro-7- (2-chloroanilino) fluoran, 3-diethylamino-6-chloro-7-dibenzylaminofluoran, 3-diethylamino-6-chloro-
7-anilinofluoran, 3-diethylamino-6-ethylethoxy-7-anilinofluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-7-methylanilinofluoran, 3-diethylamino- 7-dibenzylaminofluoran, 3-diethylamino-7-n-octylaminofluoran, 3-diethylamino-7-p-chloroanilinofluoran, 3-diethylamino-7-p-methylphenylanilinofluoran, 3-Diethylamino-7- (N-cyclohexyl-
N-benzylamino) fluoran, 3-diethylamino-7- (2-chloroanilino) fluoran, 3-diethylamino-7- (3-trifluoroanilino) fluoran, 3-diethylamino-7- (2-trifluoromethylanilino ) Fluoran, 3-diethylamino-7-
(2-ethoxyanilino) fluoran, 3-diethylamino-7- (4-ethoxyanilino) fluoran, 3-
Diethylamino-7- (2-chlorobenzylanilino)
Fluoran, 3-dimethylamino-6-chloro-7-dibenzylaminofluoran, 3-dimethylamino-6
Methyl-7-n-octylaminofluoran, 3-dimethylamino-7-dibenzylaminofluoran, 3-dimethylamino-7-n-octylaminofluoran, 3
-Dibutylamino-7- (2-fluoroanilino) fluoran, 3- [p- (p-anilinoanilino) anilino]
-6-methyl-7-chlorofluoran, 3-anilino-
7-dibenzylaminofluoran, 3-anilino-6
Methyl-7-dibenzylaminofluoran, 3-pyrrolidino-7-dibenzylaminofluoran, 3-pyrrolidino- (7-cyclohexylanilino) fluoran, 3-
Dibenzylamino-6-methyl-7-dibenzylaminofluoran, 3-dibenzylamino-7-dibenzylaminofluoran, 3-dibenzylamino-7- (2-chloroanilino) fluoran.

Examples of black color dye precursors include 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-phenylaminofluoran, and 3-dibutylamino-7. -(2-chloroanilino) fluoran, 3-dibutylamino-7- (o-chlorophenyl) aminofluoran, 3-diethylamino-
6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3
-Diethylamino-6-methyl-7-xylidinofluoran, 3-diethylamino-7- (2-chloroanilino) fluoran, 3-diethylamino-7- (o-chlorophenyl) aminofluoran, 3-diethylamino-
7- (o-chlorophenyl) amino-fluoran, 3-
Diethylamino-7- (2-carbomethoxy-phenylamino) fluoran, 3- (N-cyclohexyl-N-
Methyl) amino-6-methyl-7-anilinofluoran, 3- (N-cyclohexyl-N-methyl) amino-
6-methyl-7-phenylaminofluoran, 3- (N
-Cyclopentyl-N-ethyl) amino-6-methyl-
7-phenylaminofluoran, 3- (N-isoamyl-N-ethyl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-ani Linofluoran, 3- (N-ethyl-p
-Toluidino) -6-methyl-7- (p-toluidino)
Fluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-phenylaminofluoran, 3-
(N-methyl-N-tetrahydrofurfuryl) amino-
6-methyl-7-phenylaminofluoran, 3- (N
-Ethyl-N-tetrahydrofurfuryl) amino-6
Methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-phenylaminofluoran, 3-
Pyrrolidino-6-methyl-7-p-butylphenylaminofluoran, 3-piperidino-6-methyl-7-phenylaminofluoran, 2-phenylamino-3-methyl-6- (N-ethyl-Np -Toluyl) amino-fluoran and the like.

Next, in order to coat the surface of the dye precursor dispersion with the color control layer, it is necessary to add a vinyl monomer and a polymerization initiator to the dispersion or emulsion of the dye precursor prepared above. The color is controlled by heating to form a color control layer around the dispersed or emulsified particles. The vinyl monomer used here is a compound which has at least one vinyl-bonded functional group in its molecule, and this vinyl bond becomes an active site and is capable of addition polymerization.

Various states can be considered as a mixed state when the vinyl monomer is added to the dispersion of the dye precursor. That is, 1) Most of the dispersion or emulsion of the dye precursor and the vinyl monomer are phase-separated to form separate phases or are in an emulsified state, but a very small amount of the vinyl monomer contains the dye precursor. 2) Dispersion or emulsification of the dye precursor and complete phase separation without dissolving the vinyl monomer and the vinyl monomer at all 3) Dispersion or emulsification of the vinyl monomer Examples of the state include a state in which the vinyl monomer is completely dissolved in most or all of the liquid. Among these states, a state in which a very small amount of the vinyl monomer of 1) is dissolved in the dispersion or emulsion of the dye precursor. When the polymerization is performed in a different state, a more uniform and dense color-developing layer can be formed on the surface of the particles of the dye precursor as compared with the case where the polymerization is performed in another state, which is a preferable state. Such a state can be realized by appropriately selecting the type of the dispersion medium for dispersing the dye precursor particles and the type of the vinyl monomer.

The vinyl monomer includes a monofunctional vinyl monomer having one vinyl bond and a polyfunctional vinyl monomer having two or more vinyl bonds. By changing the content of the polyfunctional vinyl monomer, the coloring sensitivity characteristics of the coloring control layer can be changed freely. Compared with a layer formed by polymerization of a monofunctional vinyl monomer alone, a color-adjusting layer using a polyfunctional vinyl monomer in combination has a stronger crosslinked structure and can shift the color-forming start temperature to a higher temperature side.
The combination ratio of the polyfunctional vinyl monomer is 1% by weight or more and 70% by weight or less, preferably 10% by weight or more and 50% by weight or less with respect to the total weight of the vinyl monomer to adjust the color development temperature. .

The total amount of the vinyl monomer based on the dispersed particles of the dye precursor is preferably 0.5% by weight or more and 1000% by weight or less, and within this range, the polymerization proceeds without aggregation during the polymerization. In addition, a coating having a sufficient function as a color control layer can be obtained. By increasing or decreasing the amount of the vinyl monomer, the coloring sensitivity characteristics of the coloring control layer can be changed.

In the present invention, the dye precursor for low-temperature coloring and the dye precursor for high-temperature coloring are not particularly limited in order to improve the color separation. However, the dye precursor for low-temperature coloring is a monofunctional vinyl monomer only. An extremely thin color control layer is provided, and the dye precursor for high temperature color formation is coated with a monofunctional vinyl monomer only or
It is preferable to use a polyfunctional vinyl monomer in combination with the functional vinyl monomer to shift the color development temperature to a higher temperature side.

Specific examples of the monofunctional vinyl monomer having only one vinyl bond in the present invention include styrene,
α-methylstyrene, α-methoxystyrene, m-bromostyrene, m-chlorostyrene, o-bromostyrene, o-chlorostyrene, p-bromostyrene, p-chlorostyrene, p-methylstyrene, p-methoxystyrene, 2-vinylpyridine, isobutene, 3-methyl-
1-butene, butyl vinyl ether, methyl vinyl ketone, nitroethylene, vinylidene cyanide, ethylene,
Propylene, vinyl chloride, vinyl acetate, acrolein,
Methyl acrolein, acrylamide, N-methylol acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, N-octadecyl acrylamide, ethyl α-acetoxyacrylate, ethyl α-chloroacrylate, methyl α-chloroacrylate, α-cyano Methyl acrylate, α-phenylmethyl acrylate, benzyl acrylate, butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, tridecyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methoxyethyl acrylate, 2-butoxyethyl acrylate, ethoxyethoxyethyl acrylate, methyltriglycol acrylate, cycloacrylate Hexyl, tetrahydrofurfuryl acrylate, cyanoethyl acrylate, ferrocenylmethyl acrylate, glycidyl acrylate, heptafluorobutyl acrylate, methyl acrylate, octyl acrylate, methyl trifluoroacrylate, 2-chloroethyl acrylate, 2-nitrobutyl acrylate, acrylic acid, α-bromoacrylic acid, 2-hydroxyethyl acryloyl phosphate, acrylonitrile, allyl glycidyl ether, allyl acetic acid, allyl alcohol, allyl benzene, N-allyl stearyl amide, 1-butene, 2- Butene, N-vinylcaprolactam, ethyl N-vinylcarbamate, N-vinylcarbazole, crotonaldehyde, crotonic acid, 1,1-diphenylethylene, tetrafluoroethylene, Mar diethyl, 1-hexene, 1-vinylimidazole, 1
-Vinyl-2-methylimidazole, indene, diethyl maleate, maleic anhydride, maleimide, methacrylamide, benzyl methacrylate, ethyl methacrylate, ferrocenylmethyl methacrylate, glycidyl methacrylate, isopropyl methacrylate, propyl methacrylate, N-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate,
Lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, methyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methacrylic acid
2-ethoxyethyl, tetrahydrofurfuryl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 3-chloro-methacrylate
2-hydroxypropyl, methacrylic acid, methacryloxyethyl phosphate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, N-methylol methacrylamide, methacrylonitrile, methacryloyl acetone, 2-isopropenyl-2-oxazoline, 2-vinylquinoline , Vinyl benzoate, vinyl dodecyl ether, vinyl ethyl sulfoxide, vinyl formate, vinyl isobutyl ether, vinyl laurate, vinyl phenyl ether, and the like, but the present invention is not limited thereto.

Specific examples of the polyfunctional vinyl monomer having two or more vinyl bonds include ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, and octaethylene glycol diacrylate. Polyethylene glycol diacrylates such as acrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate such as tetraethylene glycol dimethacrylate, 2,2-bis (4-acryloxyethoxyphenyl) Propane, 2,2-bis (4-acryloxydiethoxyphenyl) propane, 2,2-bis (4-acryloxyt 2,2-bis (4-acryloxypolyethoxyphenyl) propanes such as ethoxyphenyl) propane, 2,2-bis (4-methacryloxyethoxyphenyl) propane, 2,2-bis (4-methacryloxydiethoxy) 2,2-bis (4-methacryloxypolyethoxyphenyl) propanes such as phenyl) propane and 2,2-bis (4-methacryloxytriethoxyphenyl) propane; allyl acrylate;
-Butanediol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, neopentyl glycol diacrylate,
1,6-hexanediol diacrylate, polypropylene glycol diacrylate, N, N'-methylenebisacrylamide, allyl methacrylate, 1,3-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, Dipropylene glycol dimethacrylate, diallyl phthalate, diallyl chlorendate, butadiene, ethyl butadiene-1-carboxylate, diethyl butadiene-1,4-dicarboxylate, diallyl melamine, diallyl phthalate, N, N-divinylaniline, divinyl ether , Divinylbenzene, divinylnaphthalene, 1,3-butanediol dimethacrylate, isoprene, pentaerythritol triacrylate, trimethylolpropane Acrylate, trimethylol ethane trimethacrylate, trimethylol propane trimethacrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, tetramethylol methane tetraacrylate, tetramethylol methane tetramethacrylate, etc. It is not limited to this.

The above-mentioned vinyl compounds according to the present invention can be used alone or in combination of two or more. When used in combination of two or more, as described above,
A combination of a compound having one vinyl bond and a compound having two or more vinyl bonds is preferable, but a combination of compounds having one vinyl bond and compounds having two or more vinyl bonds can also be used.

When some or all of these vinyl monomers are methacrylates, the methacrylates and their polymers have good affinity with the dye precursor dispersed particles provided with the color control layer, and Since the solubility in an aqueous dispersion medium is also appropriate and the polymerizability is also good, it is possible to efficiently coat the surface of the dye precursor dispersed particles by addition polymerization, and to further improve the color development characteristics such as the color development start temperature. It is also excellent in adjusting function, and is particularly preferably used in the present invention.

As the polymerization initiator to be added for the addition polymerization of the vinyl monomer, known polymerization initiators can be used, and the type of polymerization reaction is not particularly limited, such as radical polymerization, anionic polymerization, and cationic polymerization. Particularly preferably used. During the polymerization, the system may be heated as required. Specific examples of the polymerization initiator for radical polymerization are shown below. Hydrogen peroxide, cumene hydroperoxide, t-
Peroxides such as butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide and lauroyl peroxide, persulfates such as potassium persulfate and ammonium persulfate, 2,2'-azobisisobutyro Nitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionamidine ) Dihydrochloride, azo compounds such as 4,4'-azobis (4-cyanovaleric acid), a combination of hydrogen peroxide and ferrous salt, a combination of persulfate and sodium acid sulfite, cumene hydroxyperoxide and ferrous Combination of salt, combination of benzoyl peroxide and diethylaniline, combination of peroxide and metal alkyl Align, and redox initiators such as a combination of oxygen and an organometallic alkyl. These may be used not only alone but also in a mixture.

The polymerization initiator for radical polymerization is not particularly limited as long as it generates active radicals by the energy of heat or light other than those described above. In this case, it is particularly preferable to use a water-soluble polymerization initiator such as potassium persulfate, ammonium persulfate, and 2,2'-azobis (2-methylpropionamidine) dihydrochloride.

The amount of the polymerization initiator to be added is not particularly limited as long as the vinyl monomer starts the addition polymerization. Is preferably not less than 0.001 and not more than 10% by weight.

Next, the dye precursor for low-temperature coloring described above,
Specific examples of the electron-accepting color developer which reacts with a high-temperature coloring dye precursor to form a color are shown below, but the invention is not limited thereto.

4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-
Hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 4-hydroxy-4'-propoxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 3,4- Dihydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 2,4-bis (phenylsulfonyl) phenol, p-phenylphenol, p-hydroxyacetophenone, 1,1-bis (p
-Hydroxyphenyl) propane, 1,1-bis (p-
Hydroxyphenyl) pentane, 1,1-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-
(Hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane,
1,1-bis (p-hydroxyphenyl) -1-phenylethane, 1,3-di- [2- (p-hydroxyphenyl) -2-propyl] benzene, 1,3-di- [2-
(3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-di- [2- (p-hydroxyphenyl) -2-propyl] benzene, 4,4'-hydroxydiphenyl ether, 3,3'- Dichloro-4,4'-
Hydroxydiphenyl sulfide, 2,2-bis (4-
Methyl hydroxyphenyl) acetate, 2,2-bis (4-
(Hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-tert-butyl-5-methylphenol), 4
Dimethyl-hydroxyphthalate, benzyl 4-hydroxybenzoate, methyl 4-hydroxybenzoate, benzyl gallate, stearyl gallate, N, N'-diphenylthiourea, 4,4'-bis (3- (4-methyl Phenylsulfonyl) ureido) diphenylmethane, N- (4-
Methylphenylsulfonyl) -N'-phenylurea, salicylanilide, 5-chlorosalicylanilide, salicylic acid, 3,5-di-tert-butylsalicylic acid,
3,5-di-α-methylbenzylsalicylic acid, 4-
[2 '-(4-methoxyphenoxy) ethyloxy] salicylic acid, 3- (octyloxycarbonylamino) salicylic acid or a metal salt of these salicylic acid derivatives, N
-(4-hydroxyphenyl) -p-toluenesulfonamide, N- (4-hydroxyphenyl) benzenesulfonamide, N- (4-hydroxyphenyl) -1-naphthalenesulfonamide, N- (4-hydroxyphenyl)- 2-naphthalenesulfonamide, N- (4-hydroxynaphthyl) -p-toluenesulfonamide, N-
(4-hydroxynaphthyl) benzenesulfonamide,
N- (4-hydroxynaphthyl) -1-naphthalenesulfonamide, N- (4-hydroxynaphthyl) -2-naphthalenesulfonamide, N- (3-hydroxyphenyl) -p-toluenesulfonamide, N- (3- Hydroxyphenyl) benzenesulfonamide, N- (3-hydroxyphenyl) -1-naphthalenesulfonamide,
N- (3-hydroxyphenyl) -2-naphthalenesulfonamide and the like can be mentioned. These are used singly or as a mixture of two or more, and are used in a proportion of 100 to 700, preferably 150 to 400 parts by weight based on 100 parts by weight of the total amount of the dye precursor.

In the heat-sensitive recording layer according to the present invention, a binder, a sensitizer, a pigment, a surfactant and the like conventionally known in the heat-sensitive recording paper field can be added in addition to the above main constituent materials.

Examples of the binder include starches, hydroxyethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, and polymethacrylate. Sodium acrylate, polyethylene terephthalate, polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl polyester, polyacetal, polyetheretherketone, polyethersulfone, polyimide, polyamide, polyamideimide, polyaminobismaleimide , Polymethylpentene, polyphenylene oxide, polyphenylene sulfide, polyphenylene Sulfone, polysulfone, polyarylate, polyallyl sulfone, polybutadiene, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyurethane, phenolic resin, urea resin, melamine resin, melamine formalin resin, benzoguanamine resin , Bismaleimide triazine resin, alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer , Acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer Alkali salt of,
An alkali salt or ammonium salt of an ethylene / maleic anhydride copolymer, and other various polyolefin resins are used.

As the sensitizer, those having a melting point of 60 ° C. to 180 ° C. are preferable, and those having a melting point of 80 ° C. to 140 ° C. are more preferably used. Specifically, stearamide, N-hydroxymethyl stearamide,
N-stearylstearic acid amide, ethylenebisstearic acid amide, N-stearylurea, 2-benzyloxynaphthalene, m-terphenyl, 4-benzylbiphenyl, 2,2'-bis (4-methoxyphenoxy) diethyl ether, α Α'-diphenoxyxylene, bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, di-p-chlorobenzyl oxalate, di-p-methylbenzyl oxalate, dimethyl terephthalate, dibenzyl terephthalate And known sensitizers such as benzenesulfonic acid phenyl ester, bis (4-allyloxyphenyl) sulfone, 4-acetylacetophenone, acetoacetic anilides, and fatty acid anilides. These compounds can be used alone or in combination of two or more. Further, in order to obtain a sufficient thermal responsiveness, the sensitizer in the total solid content of the heat-sensitive recording layer is 5 to 5%.
It preferably accounts for 50% by weight.

Pigments include diatomaceous earth, talc, kaolin,
Inorganic and organic pigments such as calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, and urea-formalin resin are used.

In addition, higher fatty acid metal salts such as zinc stearate and calcium stearate, and waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearic acid amide, caster wax, etc.
In addition, a surfactant such as sodium dioctylsulfosuccinate, a fluorescent dye, and the like can be contained.

Further, an antioxidant and an ultraviolet absorber can be added for the purpose of improving light resistance. Examples of antioxidants include, but are not particularly limited to, hindered amine antioxidants, hindered phenol antioxidants, and sulfide antioxidants. Examples of the UV absorber include organic UV absorbers such as benzotriazole UV absorber, salicylic acid UV absorber, and benzophenone UV absorber; and inorganic UV absorbers such as zinc oxide, titanium oxide, and cerium oxide. Although an absorbent is mentioned, it is not particularly limited.

The support used in the present invention includes paper, various nonwoven fabrics, woven fabrics, plastic films such as polyethylene terephthalate and polypropylene, laminated paper laminated with a synthetic resin such as polyethylene and polypropylene, synthetic paper, and aluminum. Metal foil, glass, or the like, or a composite sheet combining these can be used arbitrarily according to the purpose, but is not limited thereto. These may be opaque, transparent, or translucent. In order to make the background appear white or another specific color, a white pigment, a colored dye or a bubble may be contained in the support or on the surface.

In order to increase the sensitivity of the heat-sensitive recording material and to prevent printing residue, these supports are provided with oil absorbing pigments, heat-insulating hollow particles, air capsules containing air therein, and the like in advance. A heat-sensitive coated paper coated so as to have a thickness of up to 30 g / m ² is particularly effective as a support. If the coating amount is less than this range, the effect of improving the sensitivity is not sufficient, and if it is more than this range, it may be difficult to obtain a uniform smooth surface. In addition, a magnetic recording material layer may be applied to the back surface of the support in advance, or an adhesive layer may be applied to the back surface after applying the heat-sensitive recording layer to process the heat-sensitive label.

In the present invention, a protective layer may be provided on the heat-sensitive recording layer in order to further improve image storability.
As a material of the protective layer, a film-forming material such as a water-soluble polymer and latex is formed as a main component.
For example, starches, hydroxyethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, sodium polyacrylate, polyethylene Terephthalate, polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl polyester, polyacetal, polyetheretherketone, polyethersulfone, polyimide, polyamide, polyamideimide, polyaminobismaleimide, polymethylpentene, Polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfone, polysulfo , Polyarylate, polyallyl sulfone, polybutadiene, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride,
Polyvinylidene chloride, polyvinyl acetate, polyurethane,
Phenolic resin, urea resin, melamine resin, melamine formalin resin, benzoguanamine resin, bismaleimide triazine resin, alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer,
Methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer Alkali salts of polymers, alkali salts or ammonium salts of ethylene / maleic anhydride copolymers, and various other polyolefin-based resins, and the like, various hardening agents for imparting water resistance, crosslinking agents, A single layer or two or more layers are laminated on the heat-sensitive recording layer by adding various pigments, ultraviolet absorbers, and the like for improving writability and running properties.

The method for forming each layer constituting the multicolor heat-sensitive recording material of the present invention on a support is not particularly limited, and it can be formed by a conventional method. For example,
Coating devices such as an air knife coater, various blade coaters, various bar coaters, various curtain coaters, etc., and various printing methods such as planographic, letterpress, intaglio, flexo, gravure, and screen can be used.

[0045]

The present invention will be described in more detail with reference to the following examples. The following parts are parts by weight, and% represents% by weight.

[1] Preparation of Low Temperature Color Dye Precursor Dispersion Preparation of Red Dye Precursor Dispersion (with Color Control Layer) 3-Diethylamino-7-chlorofluorane which is a red-colored electron-donating dye precursor 5 parts were pulverized by a ball mill together with 90 parts of a 3% aqueous polyvinyl alcohol solution to obtain a dye precursor dispersion having a volume average particle diameter of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 2.5 parts of ethyl methacrylate was added, and the temperature was raised to 70 ° C. with stirring. To this was added 2.5 parts of a 1% aqueous solution of potassium persulfate as a polymerization initiator,
The reaction was carried out for 6 hours while stirring was continued. Then, the mixture was cooled to room temperature to obtain 100 parts of a dispersion of dye precursor particles having a color control layer on the surface.

Preparation of Red Melt Dye Precursor Dispersion (with Color Control Layer) 5 parts of 3-diethylamino-7-chlorofluorane, which is a red-colored electron-donating dye precursor, is heated and melted at 180 ° C., and cooled to room temperature. After standing to cool, it was coarsely pulverized. Next, it was pulverized with a ball mill together with 90 parts of a 3% aqueous polyvinyl alcohol solution to obtain a dye precursor dispersion having a volume average particle diameter of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 2.5 parts of ethyl methacrylate was added, and the temperature was raised to 70 ° C. with stirring. To this, 2.5 parts of a 1% aqueous solution of potassium persulfate as a polymerization initiator was added, and the mixture was reacted for 6 hours while stirring was continued. Then, the mixture was cooled to room temperature to obtain 100 parts of a low-temperature coloring dye precursor dispersion liquid having a coloring control layer on the surface.

Preparation of Red Dye Precursor Dispersion (No Color Control Layer) 5 parts of 3-diethylamino-7-chlorofluorane, which is a red-colored electron-donating dye precursor, together with 95 parts of a 3% aqueous solution of polyvinyl alcohol in a ball mill. The mixture was pulverized to obtain 100 parts of a low-temperature coloring dye precursor dispersion having a volume average particle size of 1 μm.

[2] Preparation of Dye Precursor Dispersion for High-Temperature Coloring (A) Preparation of Black Dye Precursor Dispersion (With Color-Controlling Layer) 3-Dibutylamino-6 which is a black-colored electron-donating dye precursor 1. 5 parts of -methyl-7-anilinofluoran.
The mixture was pulverized with a ball mill together with 85 parts of a 5% aqueous polyvinyl alcohol solution to obtain a dye precursor dispersion having a volume average particle size of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 4 parts of methyl methacrylate and 1 part of trimethylolpropane trimethacrylate were added, and the temperature was raised to 70 ° C. with stirring. To this, 5 parts of a 1% aqueous solution of potassium persulfate as a polymerization initiator was added, and the mixture was reacted for 6 hours while stirring was continued. Then, the mixture was cooled to room temperature to obtain 100 parts of a dispersion of a high-temperature coloring dye precursor having a coloring control layer on the surface.

(B) Preparation of Black-Green Mixed Dye Precursor Dispersion (With Color-Controlling Layer) In (A), 3-dibutylamino-6-methyl-7-aniline which is a black-colored electron-donating dye precursor is prepared. 5 parts of linofluorane are replaced by 4 parts of 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-ethyl-Np-tolyl) amino-7- (N-phenyl-N-methyl) In the same manner as in (A) except that the amount of aminofluorane was changed to 1 part, 100 parts of a dispersion liquid of a high-temperature coloring dye precursor having a surface on which a color control layer was provided was obtained.

(C) Preparation of Black Melt Dye Precursor Dispersion (with Color Control Layer) 5 parts of 3-dibutylamino-6-methyl-7-anilinofluoran, which is a black color electron-donating dye precursor, 18
The mixture was heated and melted at 0 ° C., cooled to room temperature, and then coarsely pulverized. Next, it was pulverized with a ball mill together with 90 parts of a 3% aqueous polyvinyl alcohol solution to obtain a dye precursor dispersion having a volume average particle diameter of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 4 parts of methyl methacrylate and 1 part of trimethylolpropane trimethacrylate were added, and the temperature was raised to 70 ° C. with stirring. To this, 2.5 parts of a 1% aqueous solution of potassium persulfate as a polymerization initiator was added, and the mixture was reacted for 6 hours while stirring was continued. Then, the mixture was cooled to room temperature to obtain 100 parts of a low-temperature coloring dye precursor dispersion liquid having a coloring control layer on the surface.

(D) Preparation of Black-Green Mixed Dye Precursor Dispersion (with Color-Controlling Layer) In (C), 3-dibutylamino-6-methyl-7-, a black-colored electron-donating dye precursor. 5 parts of anilinofluorane are combined with 4 parts of 3-dibutylamino-6-methyl-7-anilinofluoran and 3- (N-ethyl-Np-tolyl) amino which is an electron-donating dye precursor of green color -7
In the same manner as in (C) except that 1 part of-(N-phenyl-N-methyl) aminofluoran was changed to 100 parts of a dispersion of the dye precursor for high-temperature coloring provided with a coloring control layer on the surface. Obtained.

[3] Preparation of a mother liquor for coating a multicolor heat-sensitive recording layer containing an electron-accepting color developer 10% of bis (3-allyl-4-hydroxyphenyl) sulfone, which is an electron-accepting color developer, was added in an amount of 3%. The mixture was ground with a ball mill together with 30 parts of an aqueous polyvinyl alcohol solution to obtain 40 parts of an electron-accepting compound dispersion having a volume average particle diameter of 1 μm. In addition, 10 parts of di-p-methylbenzyl oxalate were pulverized with a ball mill together with 30 parts of a 3% aqueous solution of polyvinyl alcohol to obtain 40 parts of a di-p-methylbenzyl oxalate dispersion having a volume average particle diameter of 1 μm. In addition, calcium carbonate 10
The mixture was pulverized with a homogenizer together with 30 parts of a 2% aqueous sodium hexametaphosphate solution to obtain 40 parts of a calcium carbonate dispersion having a volume average particle diameter of 1 μm. The three dispersions were mixed to prepare 120 parts of a mother liquor for coating the heat-sensitive recording layer.

[4] Preparation of Support for Thermal Coating A coating liquid composed of 100 parts of calcined kaolin, 24 parts of a 50% styrene-butadiene-based latex aqueous dispersion, and 200 parts of water was mixed with a basis weight of 50 g /
coating so that 5 g / m ² as a solid coating amount of fine paper of m ^2, and dried to prepare a thermosensitive coating support.

[5] Preparation of Multicolor Thermosensitive Recording Material Low-Temperature Coloring Dye Precursor Dispersion 100 Prepared in [1]
Parts, and 100 parts of the high-temperature coloring dye precursor dispersion prepared in [2], and (A), (B), (C), and (D) in Table 1.
Were mixed in accordance with the combination of the above, and this mixed solution was added to 120 parts of the mother liquor for coating the multicolor heat-sensitive recording layer prepared in [3] to prepare a heat-sensitive recording layer coating solution. Next, the prepared heat-sensitive recording layer coating solution is coated on the heat-sensitive coating support prepared in [4] so that the solid content is 6 g / m ^2, and the coating is dried. Examples 1 to 8 which were calendered to have a smoothness of 400 to 500 seconds and were coated with a color control layer having different sensitivities at both low and high temperatures, and a low temperature dispersed dye,
At high temperature, the multicolor heat-sensitive recording materials of Comparative Examples 1 to 4 coated with the color-developing layer were prepared.

Test 1 "Color sensitivity" of multicolor heat-sensitive recording material
Test The metal blocks of which the temperature was continuously changed were pressed against the multicolor heat-sensitive recording materials of Examples 1 to 8 and Comparative Examples 1 to 4 for 5 seconds, and the color was changed from low-temperature red to high-temperature black to cause red color. And the temperature at which the color density of the black portion and the black portion became 1.0 was measured.
The density was measured using a densitometer (Macbeth RD918), the position of the filter hole was measured in black, and the background density was also measured. The results are shown in Table 1 as the coloring temperature and the background density. The lower the temperature in both red and black, the higher the sensitivity.

Test 2 "Color bleeding" test of multicolor heat-sensitive recording material The multicolor heat-sensitive recording materials of Examples 1 to 8 and Comparative Examples 1 to 4 were equipped with a TDK print head (LH4409) and a thermal facsimile print made by Okura Electric. Using a testing machine (TH-PMD), an applied voltage of 20 volts, an applied pulse of 1.0 msec, and a red character of "H" printed 10 cm, followed by a black pulse of "H" with an applied pulse of 2.0 msec The characters were printed continuously for 10 cm, and the color tone of the characters was visually observed. "Color blur" is "H"
Is clearly expressed by the color tone of black characters, the degree of color bleeding was determined based on the color tone. ◎ indicates clear black, は indicates slightly brownish black, and △ indicates reddish brownish black.

Test 3 Test for "Chemical Resistance" of Colored Area of Multicolor Thermal Recording Material The thermal recording materials of Examples 1 to 8 and Comparative Examples 1 to 4
Using a thermal facsimile printing tester (TH-PMD) manufactured by Okura Electric Co. with a printing head (LH4409) manufactured by DK, applying an applied voltage of 20 volts and an applied pulse of 2.0 milliseconds, and then performing black solid printing, and then printing on a printing surface. , Soft vinyl chloride film (Kokuyo soft card case), 100g
After standing for 24 hours in an environment of 40 ° C. under a pressure of / cm ^2, the degree of image deterioration due to the plasticizer contained in the film was examined. The optical density of the image area before and after the test was measured using a densitometer (Macbeth RD918) and the position of the filter hole was measured in black, and the residual ratio of the image area% [(optical density of image area after test /
"Optical density in the image area before the test) x 100] and" Chemical resistance "
Table 1 shows the results.

[0059]

[Table 1]

As can be seen from Table 1, those coated with the color control layers having different sensitivities at both low temperature and high temperature (Examples 1 to 8) showed color development only at high temperature as a whole in terms of background density, chemical resistance and color blur. It turns out that it is more excellent than what has a control layer (Comparative Examples 1-4). The combination of two dye precursors is more excellent in chemical resistance than the single dye precursor, and the one obtained by melting the dye precursor to make it amorphous is more effective.

Regarding color bleeding, when a low-temperature complementary color is used in combination with the high-temperature side, the low-temperature color bleeding around the character becomes inconspicuous, probably because the color tone in the high-temperature portion becomes deep. In the column where the low-temperature part was covered with the color control layer (Examples 1 to 8), the sensitivity of the low-temperature part was lower than that in the case where the coating was not coated (Comparative Examples 1 to 4). Obviously, this means that the sensitivity of the low-temperature color around the high-temperature printed character is low, which contributes to the reduction of the spread width.

[0062]

As described above, one or more low-temperature coloring dye precursors and one or more high-temperature coloring dye precursors are each coated with a color control layer having a different sensitivity, and the low-temperature coloring dye is coated on the high-temperature side. A multicolor heat-sensitive recording material that is excellent in both background density, chemical resistance, and color bleeding by using a dye precursor that is a complementary color of the precursor in combination and further making the dye precursor amorphous at low and high temperatures. was gotten.

Claims (4)

[Claims] Claims: 1. An electron-donating, usually colorless to light-color, low-temperature coloring dye precursor and a high-temperature coloring dye precursor, and an electron-accepting developer for coloring the dye precursor upon heating on a support. Provided a heat-sensitive recording layer, in a multicolor heat-sensitive recording material that develops different colors depending on the difference in temperature, the dye precursor for low-temperature coloring and the dye precursor for high-temperature coloring,
A multicolor heat-sensitive recording material, which is coated with different color-developing layers obtained by polymerizing vinyl monomers. 2. The dye precursor for low-temperature coloring and the dye precursor for high-temperature coloring each comprise one or more dye precursors,
The multicolor heat-sensitive recording material according to claim 1, wherein one of the high-temperature coloring dye precursors is a dye precursor that is complementary to the low-temperature coloring dye precursor. 3. The multicolor heat-sensitive recording material according to claim 1, wherein the low-temperature coloring dye precursor and the high-temperature coloring dye precursor are amorphous dye precursors composed of one or more dye precursors. . 4. The color control layer wherein the color formation sensitivity is changed by changing a mixing ratio of a monofunctional vinyl monomer and a bifunctional or higher polyfunctional vinyl monomer. The multicolor heat-sensitive recording material according to claim 1, 2 or 3.