JP2002307832A - Multi-color heat-sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-color heat-sensitive recording medium which has good ink receiving properties while heat transfer recording is performed and can perform recording without having no possibility of generating sticking, scum of printing, etc., while heat-sensitive recording is performed in the heat- sensitive recording medium provided with a heat-sensitive recording layer consisting of at least one layer comprising at least two electron-donating ordinarily colorless or light-colored dye precursors which are developed into different color tones each other and an electron-accepting color developing agent which reacts by heating and develops the dye precursor on a substrate. SOLUTION: By incorporating polyolefin resin particles in an over-coat layer for the heat-sensitive recording medium, the multi-color heat-sensitive recording medium which has good ink receiving properties while heat transfer recording is performed and can perform recording without having no possibility of generating sticking, tailing of printing, etc., while heat-sensitive recording is performed is provided.

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 medium having a multicolor heat-sensitive recording layer on a support which develops different colors depending on the heating conditions and an overcoat layer having heat transfer receptivity. Things.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording medium comprises, on a support, an electron-donating, usually colorless or pale-colored dye precursor, and an electron-accepting developer, which reacts upon heating to form the dye precursor. A heat-sensitive recording layer consisting of a heat-sensitive recording component as the main component is provided. By heating with a thermal head (heat head), hot pen, laser light, etc., the dye precursor and the developer react instantaneously. A color image can be obtained.
It is disclosed in JP-A-3-4160 and JP-B-45-14039.

Such a thermosensitive recording medium can be recorded by a relatively simple device, has advantages such as easy maintenance, and no noise generation, and has a measuring recorder, a facsimile, a printer, and a computer terminal. It is used in a wide range of fields, such as vending machines for labels, labels, and ticketes. Particularly in recent years, receipts of gas, water, electricity, etc.
Thermal recording media are also used for financial-related recording paper, such as TM usage statements and various receipts.
As described above, as the uses have been diversified, there has been an increasing demand for a multicolor heat-sensitive recording medium capable of developing two or more colors depending on the heating temperature.

On the other hand, from the back of a heat-sensitive ribbon having a heat-meltable ink coated on a base material, a thermal head heats the ink according to an information signal to melt the ink and transfers the melted ink onto a recording medium. The recording method is also performed using a relatively simple device. In the thermal transfer recording method, multicolor printing can be performed relatively easily by using a plurality of ink ribbons having different color tones. On the other hand, a plurality of ink ribbons have to be used, and the recent trend of cost reduction and waste reduction has increased the demand for a thermal recording system which does not require replacement and replacement of ink ribbons.

The thermal recording apparatus and the thermal transfer recording apparatus are often used using the same apparatus due to structural similarity. There is a demand for a heat-sensitive recording medium that can be used in both types without concern.

To briefly describe the properties desired for each recording medium, in a thermal transfer recording medium, the surface of the ink ribbon pressed by the thermal head and the recording medium are completely adhered to each other so as to receive the ink uniformly and prevent the ink from falling off. It is necessary to bind well. For this reason, those obtained by applying a polymer having sufficient binding properties to the binder component of the ink on a support are widely used. On the other hand, in the case of a heat-sensitive recording medium, it is necessary to provide a heat-sensitive recording layer which develops color by heating on a support.

Therefore, it is desirable that a recording medium corresponding to these two recording methods has a heat-sensitive recording layer provided on a support and a thermal transfer receiving layer provided thereon. When such a recording medium is used as a heat-sensitive recording medium, sticking, printing residue and the like are liable to occur due to the use of a material such as a polymer having a high thermal transfer ink receptivity. Combination is required. On the other hand, the combined use of a pigment and a lubricant decreases the surface smoothness and the binding property with the ink, and is not preferable as a thermal transfer recording medium. Therefore, in reality, there is no recording medium that can sufficiently satisfy the two recording methods.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reaction between two or more kinds of electron-donating, usually colorless or pale-colored dye precursors which form different colors on a support by heating. In a multicolor heat-sensitive recording medium provided with at least one heat-sensitive recording layer containing at least one electron-accepting color developer for coloring a dye precursor, good ink receptivity can be obtained even during thermal transfer recording. It is an object of the present invention to provide a multicolor heat-sensitive recording medium which has a recording property and can perform recording without generating sticking, printing residue and the like even during heat-sensitive recording.

[0009]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that polyolefin resin particles are contained in the overcoat layer of a multicolor heat-sensitive recording medium, whereby
Thus, a multicolor heat-sensitive recording medium having good ink receptivity even during thermal transfer recording and capable of performing recording without causing sticking, print residue, and the like during heat-sensitive recording has been invented.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The multicolor heat-sensitive recording medium of the present invention comprises two or more kinds of usually colorless or light-colored electron-donating dye precursors which form different colors on a support, and heats the dye precursors. It is provided by providing at least one heat-sensitive recording layer containing an electron-accepting color developer which causes color development. In the present invention, as the two or more dye precursors that develop colors different from each other, those that emit red, yellow, blue, green, and black colors can be used. Specific examples are shown below, but the present invention is 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.

The yellow dye precursors 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-methylindo -Ru-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-methyl) Indole-3-yl) -3- (2-ethoxy-4-ethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2 -Ethoxy-4-dimethylaminophenyl) -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- Methylindol-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-methylindole-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-methylindo -Ru-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-methylindo-
Ru-3-yl) -3- (2-ethoxy-4-pyrrolidylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-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 , 3- (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-methyl) Indole-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
-Methylindole-3-yl) -3- (2-methylethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-
Yl) -3- (2-cyclohexylethyl-4-diethylaminophenyl) -4-azaphthalide, 3- (2-ethylindole-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-ethylindo -R-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-phenylindole- 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-methylindole-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-methyl) Indole-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-methylindo -Rule-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-methylindo -Ru-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-methylindo- Ru-3-yl) -3- (2-
Ethoxy-4-diethylaminophenyl) -4,7-diazaphthalide, 3- (1-nonyl-2-methylindo-
Ru-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-methylindole-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-heptyl-2-methylindole- 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-Np-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.

As a typical method for realizing multi-color heat-sensitive recording in the present invention, the method of providing two or more heat-sensitive recording layers is as follows: (1) A dye precursor which forms colors different from each other is formed by a high-temperature coloring layer and a low-temperature coloring layer. In high-temperature printing following low-temperature printing, there is a method of obtaining a color mixture of a low-temperature hue and a high-temperature hue (JP-A-54-097048). This method has low sensitivity because the high-temperature coloring layer is under the layer, and if it is attempted to increase the sensitivity, color mixing of high-temperature colors cannot be avoided during low-temperature color printing, and color separation is still insufficient. In order to improve this color separation, (2) dye precursors that form colors different from each other are stratified into a high-temperature coloring layer and a low-temperature coloring layer via a decoloring agent layer, and at the time of high-temperature printing following low-temperature printing, A decoloring type method (Japanese Patent Application Laid-Open No. 55-139470 and Japanese Patent Application Laid-Open No. 57-178791) has been proposed in which printing is performed while the low-temperature coloring layer is being decolorized. In this method, the color separation is very good because the low-temperature color is erased during high-temperature coloring, but the presence of the decoloring agent in the heat-sensitive layer raises concerns about the long-term storage of images. There is still a disadvantage that the production cost is high.

On the other hand, a method for obtaining multicolor recording with good color separation in a single layer of the heat-sensitive recording layer is as follows: (3) A plurality of dye precursors which develop colors different from each other are contained in the same layer. (Japanese Patent Application Laid-Open No. 8-282115). In this method, color separation is good because the dye precursors are isolated from each other by the capsule membrane, but since the oily liquid is contained in the microcapsules, the capsules are destroyed by the pressure and friction during handling and the background coloration Occurs, and there is also a disadvantage in the storability of the image.

Further, (4) a method in which a high-temperature coloring dye precursor is formed into composite fine particles of at least one polymer substance selected from polyurea and polyurethane, and is used in combination with solid fine particles of a low-temperature dye precursor (Japanese Patent Laid-Open No. 9-1997). No. 142025) has also been proposed. In this method, in order to completely cover the dye precursor, a large amount of polyurea or polyurethane is contained, and color separation is good, but there is a difficulty in insufficient color sensitivity. Further, (5) a method of covering at least one or more of two or more dye precursors that develop colors with different color tones with a color control layer polymerized with a compound having an unsaturated carbon bond (JP-A-11-311)
01118 publication). In this method, the dye precursor particles are covered with a solid thin polymer film (color-controlling layer), and the color-forming sensitivity is controlled by controlling the thickness of the color-controlling layer and the material used. The color separation between the color and the high-temperature color can be controlled, but the color sensitivity itself becomes lower due to the presence of the color control layer. As a method for realizing multicolor thermal recording in the present invention, color separation, sensitivity,
The method (5) described above is particularly preferred for reasons such as storage stability.

Next, examples of the electron-accepting color developer which reacts with the above-described dye precursor to form a color include the following.

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 mass, based on 100 parts by mass of the total amount of the dye precursor.

In the multicolor heat-sensitive recording medium of the present invention, a heat-fusible substance can be contained in the heat-sensitive recording layer as needed in order to improve the thermal response. In this case, 60
C. to 180.degree. C. are preferred, especially 80.degree.
Those having a melting point of from 140C to 140C are more preferred.

Examples of such heat-fusible substances (sensitizers) for improving the thermal responsiveness include N-hydroxymethylstearic amide, stearic amide, barmitic amide, oleic amide, ethylenebisstearin Acid amide, ricinoleamide, paraffin wax,
Waxes such as microcrystalline wax, polyethylene wax, rice wax and carnauba wax; naphthol derivatives such as 2-benzyloxynaphthalene; biphenyl derivatives such as p-benzylbiphenyl, 4-allyloxybiphenyl and m-terphenyl;
Polyether compounds such as -bis (3-methylphenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, and di (oxalate) Examples thereof include carbonic acid or oxalic acid diester derivatives such as (p-chlorobenzyl) ester, but the present invention is not limited thereto.

These sensitizers can be used alone or in combination of two or more. Further, in order to obtain a sufficient thermal responsiveness, when used in a thermosensitive recording layer mainly containing a colorless or pale-colored electron-donating dye precursor and an electron-accepting developer, the electron-donating dye 20 for precursor
To 400% by mass, more preferably 30 to
It is more preferable to use 350% by mass.

The multicolor heat-sensitive recording layer in the present invention is formed by providing a heat-sensitive recording component on a support. The method of providing the heat-sensitive recording component on the support is not particularly limited, and a method of applying a coating liquid containing the heat-sensitive recording component, a method of printing an ink containing the heat-sensitive recording component, and the like can be used. Further, the heat-sensitive recording layer may contain a binder, if necessary. The binder contained in the heat-sensitive recording layer is not particularly limited, but those having little effect on the coloring properties of the heat-sensitive recording component are particularly preferably used.

Specific examples of the binder used in the multicolor heat-sensitive recording layer and the overcoat layer in the present invention include starches, hydroxyethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, and the like.
Water-soluble resins such as gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid, and 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, 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, Lilonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, acrylamide / acrylate ester copolymer, acrylamide / acrylate / methacrylic acid terpolymer And water-dispersed resins such as an alkali salt of a styrene / maleic anhydride copolymer, an alkali salt or an ammonium salt of an ethylene / maleic anhydride copolymer, and these can be used alone or in combination of two or more. it can.

As the polyolefin resin particles used in the overcoat layer in the present invention, not only homopolymers of single olefins but also copolymers with various monomers can be used.

Examples of the homocopolymer include polyethylene resin, polypropylene resin and polybutylene resin. Among them, polyethylene resin and polypropylene resin are preferable, and low density polyethylene resin is particularly preferable.

Among copolymers with various monomers, ethylene-polar monomer copolymers are preferred. Among them, ethylene-methyl (meth) acrylate copolymer, ethylene-ethyl (meth) acrylate copolymer, ethylene-propyl (meth) acrylate copolymer,
Ethylene-butyl (meth) acrylate copolymer, ethylene-hexyl (meth) acrylate copolymer, ethylene-
(Meth) acrylic acid-2-hydroxyethyl copolymer,
Ethylene- (meth) acrylate copolymers such as ethylene- (meth) acrylate-2-hydroxypropyl copolymer, ethylene- (meth) glycidyl acrylate copolymer, and ethylene- (meth) acrylic acid copolymer Copolymer, ethylene-maleic acid copolymer, ethylene-fumaric acid copolymer, ethylene-ethylenically unsaturated acid copolymer such as ethylene-crotonic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl propionate More preferred are ethylene-vinyl ester copolymers such as copolymers, ethylene-vinyl butyrate copolymers, ethylene-vinyl stearate copolymers, and ethylene-styrene copolymers. More preferred are ethylene-vinyl ester copolymer and ethylene- (meth) acrylate copolymer, and particularly preferred is ethylene-vinyl acetate copolymer.
The molecular weight of the ethylene-polar monomer copolymer may be such that it can form a film after being applied to a substrate and dried.
The mass ratio of ethylene to the polar monomer is 95/5 to 50
/ 50.

When the average particle size of the polyolefin resin particles used in the overcoat layer in the present invention is 1 μm or less, sticking is apt to occur in the case of thermal recording, and when the average particle size is 20 μm or more, thermal transfer recording is performed. In this case, the adhesion to the ink ribbon is reduced.
Printing troubles such as white spots are likely to occur. Therefore, the average particle size of the polyolefin resin particles used in the present invention,
The thickness is preferably 1 to 20 μm, more preferably 2 to 15 μm.
μm, and particularly preferably 3 to 10 μm.

When the solid content concentration of the polyolefin resin particles used in the overcoat layer in the present invention in the overcoat layer is 5% by mass or less, the number of polyolefin resin particles existing near the coating surface decreases, and the heat sensitivity When recording is performed, sticking is likely to occur.
On the other hand, when the solid content concentration of the polyolefin-based resin particles in the overcoat layer is 90% by mass or more, the binding force of the binder is weak, the particles easily fall off, and the dusting, the thermal transfer ink easily falls off, and the like. . Therefore, the solid content concentration in the overcoat layer of the polyolefin resin particles used in the overcoat layer in the present invention is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, and particularly preferably 15 to 70% by mass. % By mass.

Further, when the coating amount of the overcoat layer is more than 3 g / m ² in solid content, when the thermal recording is performed,
Since the heat transfer to the heat-sensitive recording layer is reduced, the color sensitivity and the color density are reduced. Therefore, the coating amount of the overcoat layer in the present invention is 3 g / m ^{2 in} solid content.
The following is preferred, more preferably 2.5 g / m ² or less, and particularly preferably 1.5 g / m ² or less.

As the support used in the present invention, paper,
Various nonwoven fabrics, woven fabrics, plastic films such as polyethylene terephthalate and polypropylene, polyethylene,
Laminated paper laminated with synthetic resin such as polypropylene, synthetic paper, metal foil such as aluminum, glass or the like, or a composite sheet combining these can be used arbitrarily according to the purpose, but is not limited thereto. Absent. 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 the layer structure of the multicolor thermosensitive recording medium of the present invention, an intermediate layer can be provided between the thermosensitive recording layer and the support or between the thermosensitive recording layer and the overcoat layer, if necessary. When there are two or more heat-sensitive recording layers, an intermediate layer can be provided between different heat-sensitive recording layers. In these cases, the intermediate layer may be composed of two or three or more layers. Further, a back coat layer for curling prevention and antistatic, a magnetic recording layer for magnetic recording, and an IJ for ink jet recording are provided on the surface of the support opposite to the surface on which the heat-sensitive recording layer is provided.
Various types of recording layers such as a recording layer can be provided.

The multicolor heat-sensitive recording layer according to the present invention comprises an aqueous dispersion obtained by pulverizing a color-forming component and a binder.
And the like, and the mixture can be obtained by coating and drying on a support. In this case, if desired, a plurality of coloring components may be contained in the same layer, or a plurality of layers may be contained to form a multi-layer structure, but it is preferable that the coloring components are contained in the same layer.

In the multicolor heat-sensitive recording medium of the present invention, a light-heat conversion material can be contained in any layer and support in the multicolor heat-sensitive recording medium in order to perform printing with a laser beam.

In any layer of the multicolor heat-sensitive recording medium of the present invention, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, hydroxide Inorganic and organic pigments such as aluminum and urea-formalin resins, as well as higher fatty acid metal salts such as zinc stearate and calcium stearate, and waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearic amide, and caster wax. ,Also,
A dispersant such as sodium dioctylsulfosuccinate, a surfactant, a fluorescent dye, and the like can also be contained.

For the purpose of improving the light resistance, an antioxidant and an ultraviolet absorber can be added. Examples of the antioxidant include a hindered amine antioxidant, a hindered phenol antioxidant, and a sulfide antioxidant. Examples of the UV absorber include organic UV absorbers such as benzotriazole UV absorber, salicylic acid UV absorber, benzophenone UV absorber, and inorganic UV absorbers such as zinc oxide, titanium oxide, and cerium oxide. Is mentioned.

[0038]

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

Example 1 (A1) Preparation of Coating Solution for Forming Multicolor Thermal Recording Layer (High-Temperature Coloring Layer) 3 parts of 3-dibutylamino-6-methyl-7-anilinofluoran, a black coloring dye precursor Was milled with a ball mill together with 7 parts of a 2% aqueous solution of polyvinyl alcohol to obtain 10 parts of a dye precursor dispersion having a volume average particle diameter of 1 μm. Then
5 parts of 2,2'-bis {4- (4-hydroxyphenylsulfonyl) phenoxy} diethyl ether, which is a color developer, is pulverized with a ball mill together with 10 parts of a 2% aqueous solution of polyvinyl alcohol to obtain a color developer having a volume average particle diameter of 1 μm. Dispersion 15
Got a part. The two dispersions were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer (high-temperature coloring layer).

(A2) Preparation of a Coating Solution for Forming a Multicolor Thermal Recording Layer (Low-Temperature Coloring Layer) Three parts of 3-diethylamino-7-chlorofluorane, which is a red coloring dye precursor, is added to a 2% aqueous solution of polyvinyl alcohol 7
And 10 parts of a dye precursor dispersion having a volume average particle diameter of 1 μm. Next, 5 parts of N- (4-hydroxyphenyl) -p-toluenesulfonamide, which is an electron-accepting developer, was pulverized in a ball mill together with 10 parts of a 2% aqueous solution of polyvinyl alcohol to give a volume average particle diameter of 1 part.
15 parts of a μm electron-accepting developer dispersion were obtained. Further, 5 parts of di-p-methylbenzyl oxalate was pulverized with a ball mill together with 10 parts of a 2% aqueous polyvinyl alcohol solution to obtain 15 parts of a di-p-methylbenzyl oxalate dispersion having a volume average particle diameter of 1 μm. Further, 3 parts of calcium carbonate was pulverized with a homogenizer together with 7 parts of a 2% aqueous sodium hexametaphosphate solution to obtain 10 parts of a calcium carbonate dispersion having a volume average particle diameter of 1 μm. The four dispersions were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer (low-temperature coloring layer).

(B) Preparation of heat-sensitive coated paper 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 high-quality paper having a basis weight of 50 g / m ² . The resulting mixture was coated so as to have a solid content of 10 g / m ² and dried to prepare a heat-sensitive layer coated paper.

(C1) Preparation of Coating Solution for Forming Overcoat Layer 45 parts of 20% acrylic emulsion, 40% low-density polyolefin dispersion (Mitsui Chemicals: Chemipearl M20)
0, average particle diameter 6 μm) 45 parts, and calcium carbonate 3
The mixture was mixed with 10 parts of a calcium carbonate dispersion obtained by pulverizing with a homogenizer together with 7 parts of a 2% aqueous sodium hexametaphosphate solution to prepare a coating liquid for forming an overcoat layer.

(D1) Preparation of multicolor heat-sensitive recording layer The heat-sensitive coating paper prepared in (B) was coated with the coating solution for forming a heat-sensitive recording layer (high-temperature coloring layer) prepared in (A1) on a solid basis. Was 3 g / m ² and dried. Further, a coating solution for forming a heat-sensitive recording layer (low-temperature color-forming layer) prepared in (A2) was applied thereon so that the solid content was 2 g / m ² .
After drying, the coated surface was calendered so that the Bekk smoothness was 400 to 500 seconds, to provide a multicolor heat-sensitive recording layer.

On the multicolor heat-sensitive recording layer provided in (D1),
After the coating liquid for forming an overcoat layer prepared in (C1) is applied so that the solid coating amount is 1.5 g / m ² and dried, the coating surface has a Beck smoothness of 600 to 800 seconds. A calender treatment was performed to obtain a multicolor heat-sensitive recording medium.

Example 2 (A3) Preparation of Coating Solution for Forming Multicolor Thermosensitive Recording Layer 3-Diethylamino-6-methyl-7- (3-trifluoromethylanilino, a black-colored electron-donating dye precursor 5) Fluorane was pulverized by a ball mill together with 90 parts of a 2.5% aqueous solution of polyvinyl alcohol to obtain a dye precursor dispersion having a volume average particle diameter of 1 μm. Next, this dispersion was transferred to a polymerization vessel, to which 2 parts of methyl methacrylate and 0.5 part of ethylene glycol dimethacrylate were added, and the temperature was raised to 70 ° C. while stirring. 2.5% of the polymerization initiator
2.5 parts of an aqueous potassium persulfate solution was added, and the mixture was reacted for 8 hours while stirring was continued. It is then cooled to room temperature,
As a result, 100 parts of a dispersion liquid of electron-donating dye precursor particles having a color-developing layer on the surface was obtained. Also, 3 parts of 3-diethylamino-7-chlorofluorane, which is a red color dye precursor, is pulverized in a ball mill together with 7 parts of a 2% aqueous solution of polyvinyl alcohol to obtain a dye precursor dispersion 10 having a volume average particle diameter of 1 μm.
Got a part. Next, the electron accepting developer 2,2-
6 parts of bis (4-hydroxyphenyl) propane were ground with a ball mill together with 14 parts of a 2% aqueous solution of polyvinyl alcohol to obtain an electron-accepting developer dispersion 2 having a volume average particle diameter of 1 μm.
0 parts were obtained. In addition, 6 parts of 2-benzyloxynaphthalene as a sensitizer were pulverized with a ball mill together with 14 parts of a 2% aqueous solution of polyvinyl alcohol to give a 2-μm-average particle diameter of 1 μm.
20 parts of a benzyloxynaphthalene dispersion were obtained. Further, 5 parts of calcium carbonate was pulverized with a homogenizer together with 10 parts of a 2% aqueous sodium hexametaphosphate solution to obtain 15 parts of a calcium carbonate dispersion having a volume average particle diameter of 1 μm.
The above five dispersions were mixed to prepare a coating liquid for forming a multicolor heat-sensitive recording layer.

(C2) Preparation of Coating Solution for Forming Overcoat Layer 45 parts of 20% acrylic emulsion, 45 parts of 40% vinyl acetate copolymer polyolefin dispersion (Mitsui Chemicals: Chemipearl V300, average particle diameter 8 μm), Further, 10 parts of a calcium carbonate dispersion obtained by grinding 3 parts of calcium carbonate and 7 parts of a 2% aqueous sodium hexametaphosphate solution with a homogenizer were mixed to prepare a coating liquid for forming an overcoat layer.

(D2) Preparation of multicolor heat-sensitive recording layer The multicolor heat-sensitive recording layer forming coating liquid prepared in (A3) was coated on the heat-sensitive coating paper prepared in (B) at a solid content of 5 g. /
After coating and drying to obtain m ² , the coated surface was calendered so that the Bekk smoothness was 400 to 500 seconds to provide a multicolor heat-sensitive recording layer.

On the multicolor heat-sensitive recording layer provided in (D2),
After coating and drying the coating liquid for forming an overcoat layer prepared in (C2) so that the coating amount of solid content is 1.5 g / m ² , the coating surface has a Beck smoothness of 600 to 800 seconds. A calender treatment was performed to obtain a multicolor heat-sensitive recording medium.

Example 3 (C3) Preparation of Coating Solution for Forming Overcoat Layer 45 parts of a 20% acrylic emulsion and high-density polyethylene resin particles (flow beads HE304 manufactured by Sumitomo Seika Co., Ltd.)
(0, average particle diameter: 12 μm), 18 parts, and 3 parts of calcium carbonate were mixed with 7 parts of a 2% aqueous sodium hexametaphosphate solution and 10 parts of a dispersion obtained by pulverizing with a homogenizer to prepare a coating liquid for overcoating.

On the multicolor heat-sensitive recording layer provided in (D2),
After the coating solution for forming an overcoat layer prepared in (C3) is applied and dried so that the solid content is 1.5 g / m ² , the coating surface has a Beck smoothness of 600 to 800 seconds. A calender treatment was performed to obtain a multicolor heat-sensitive recording medium.

Example 4 The polyolefin resin particles used for the overcoat layer were dispersed in a 40% low molecular weight polyolefin dispersion (manufactured by Mitsui Chemicals:
The same operation as in Example 2 was carried out except that the composition was changed to Chemipearl WF640 (average particle diameter: 1 μm), to produce a multicolor heat-sensitive recording medium.

Example 5 Polyolefin resin particles used in the overcoat layer were polyethylene resin particles (Flocene U, manufactured by Sumitomo Seika Chemical Co., Ltd.).
F20, average particle size 20 to 30 μm), except that the same operation as in Example 3 was carried out to produce a multicolor thermosensitive recording medium.

Example 6 (C4) Preparation of Coating Solution for Forming Overcoat Layer 79 parts of 20% acrylic emulsion, low-density polyethylene resin particles (manufactured by Sumitomo Seika: Flow beads LE108)
0, an average particle diameter of 6 μm), and 3 parts of calcium carbonate, together with 7 parts of a 2% aqueous sodium hexametaphosphate solution, and 10 parts of a calcium carbonate dispersion obtained by pulverizing with a homogenizer to form a coating liquid for forming an overcoat layer. Prepared.

On the multicolor heat-sensitive recording layer provided in (D2),
The coating liquid for forming an overcoat layer prepared in (C4) was applied so as to have a solid coating amount of 1.5 g / m ² and dried, and the coating surface had a Beck smoothness of 600 to 800 seconds. A calender treatment was performed to obtain a multicolor heat-sensitive recording medium.

Example 7 (C5) Preparation of Coating Solution for Forming Overcoat Layer 50 parts of 20% acrylic emulsion, low-density polyethylene resin particles (flow beads LE108, manufactured by Sumitomo Seika)
(0, average particle diameter: 6 μm) to prepare a coating liquid for forming an overcoat layer.

On the multicolor heat-sensitive recording layer provided in (D2),
After coating and drying the coating liquid for forming an overcoat layer prepared in (C5) so that the coating amount of solid content is 1.5 g / m ² , the coating surface has a Beck smoothness of 600 to 800 seconds. A calender treatment was performed to obtain a multicolor heat-sensitive recording medium.

Example 8 A multicolor heat-sensitive recording medium was produced in the same manner as in Example 2 except that the coating amount of the solid content of the overcoat layer was changed to 3 g / m ² .

Comparative Example 1 (C6) Preparation of Coating Solution for Forming Overcoat Layer 20 parts of 10% aqueous polyvinyl alcohol solution, 2 parts of glyoxal modified polyacrylic acid, 15 parts of calcium carbonate
And 60 parts of water were pulverized with a homogenizer to prepare a coating solution for forming an overcoat layer for thermal recording paper.

On the multicolor heat-sensitive recording layer provided in (D2),
After the coating solution for forming an overcoat layer prepared in (C6) is applied and dried so that the solid content is 1.5 g / m ² , the coating surface has a Beck smoothness of 600 to 800 seconds. A calender treatment was performed to obtain a multicolor heat-sensitive recording medium.

Comparative Example 2 (C7) Preparation of Coating Solution for Forming Overcoat Layer 50 parts of calcium carbonate and 0.5 part of sodium polyacrylate were dispersed in water to prepare a pigment slurry. 50 parts of styrene-acrylic organic pigment (manufactured by Mitsui Chemicals: Grosdale 162TX) is added to this pigment slurry, 20 parts of polyvinyl alcohol and 3 parts of styrene-butadiene copolymer latex are added, and the mixture is stirred and diluted with water. With a solid content of 35%, a coating liquid for forming an overcoat layer for thermal transfer recording paper was prepared.

On the multicolor heat-sensitive recording layer provided in (D2),
After the coating solution for forming an overcoat layer prepared in (C7) is applied and dried so that the solid content is 2 g / m ² , the coating surface has a Beck smoothness of 600 to 800 seconds. To prepare a multicolor thermosensitive recording medium.

Test 1 Thermal Recording Test A thermal facsimile printing tester (TH-PMD, manufactured by Okura Electric Co., Ltd.) equipped with a print head (LH4409) manufactured by TDK was used for the multicolor thermal recording media of Examples 1 to 8 and Comparative Examples 1 and 2. High-energy printing (black printing) was performed with an applied voltage of 20 volts and an applied pulse of 2.0 milliseconds. Further, low energy printing (red printing) was performed with an applied voltage of 20 volts and an applied pulse of 1.0 millisecond. Sticking during printing,
Table 1 shows the results of visually observing the printing residue and the printing quality.

Test 2 Thermal Transfer Recording Test A thermal transfer ink ribbon was placed on the coated surface of the multicolor thermal recording media of Examples 1 to 8 and Comparative Examples 1 and 2, and an applied voltage of 20 volts and an applied pulse were applied in the same manner as in the thermal recording test. After heating for 0.8 milliseconds, the ink ribbon was removed and the print quality of the image was visually observed. Table 1 shows the results.

[0064]

[Table 1]

The heat-sensitive recording test in Table 1 was evaluated according to the following evaluation criteria. (1) Printing quality A: The dot reproducibility is extremely excellent. ：: Good dot reproducibility. Δ: Poor dot reproducibility, insufficient for practical use. X: The dot reproducibility was extremely poor and not suitable for practical use. (2) Sticking ：: There is no printing noise, and it is extremely excellent. ：: Although printing sound is produced, there is no effect on the image. Δ: Printing sound and image are slightly affected. X: Practical due to print noise and image overtones. (3) Scrap: Extremely excellent without any sticking of scrap. ：: Scrap adhered, but no effect on printing. Δ: Scrap adhered, slightly affecting printing. ×: Scrap adheres, has an effect on printing, and is not suitable for practical use.

The thermal transfer recording test in Table 1 was evaluated according to the following evaluation criteria. (1) Printing quality A: The dot reproducibility is extremely excellent. ：: Good dot reproducibility. Δ: Poor dot reproducibility, insufficient for practical use. X: The dot reproducibility was extremely poor and not suitable for practical use.

As is clear from Table 1, the thermal recording papers of Examples 1 and 2 use low-density polyolefin resin particles or vinyl acetate-based polyolefin copolymer resin particles for the overcoat layer. And excellent binding to the thermal transfer ink ribbon, and showed good results in both thermal recording and thermal transfer recording. In particular, in Example 2, a dye precursor having a surface on which a color control layer was provided was used, and the configuration of the multicolor heat-sensitive recording layer was one layer, so that color separation was excellent, low energy (red printing),
Good results were obtained in all cases of high energy (black printing). As described above, these thermosensitive recording media have excellent recording characteristics of both thermosensitive recording and thermal transfer recording, and a single recording medium can support different recording methods.

When the high-density polyolefin resin particles of Example 3 were used, the particles became harder than the low-density polyolefin resin, so that matching with the print head deteriorated.
Performing low-temperature thermal recording (red printing) and thermal transfer recording resulted in a slight decrease in print quality, but at a level that was not problematic for practical use.

When the average particle size of the polyolefin resin particles used in the overcoat layer in Example 4 was 1 μm, the adhesion to the print head was high. Was at a level where there was no practical problem without any effect. On the other hand, the polyolefin resin particles used in the overcoat layer of Example 5 had an average particle size of 2
In the case of 0 to 30 μm, since the adhesion to the thermal transfer ink ribbon is reduced, the print quality of thermal transfer recording is slightly reduced, but the reproducibility of the dots is good, and the level is practically acceptable.

When the solid content concentration of the polyolefin-based resin particles in the overcoat layer of Example 6 was 5%, the adhesion to the print head was high, so that printing noise was generated when thermal recording was performed. However, there was no effect on the image and there was no practical problem. On the other hand, when the solid content concentration of the polyolefin-based resin particles in the overcoat layer of Example 7 was 90%, the generation of print residue was slightly observed when thermal recording was performed, but there was no effect on the image and there was a problem in practical use. Did not.

When the solid coating amount of the overcoat layer in Example 8 was 3 g / m ² , heat transfer to the heat-sensitive recording layer was reduced when heat-sensitive recording was performed. Was slightly reduced, but at a level that was not problematic in practical use.

In Comparative Example 1, since an overcoat layer for thermal recording paper was provided, good results were obtained in the thermal recording test. However, in the thermal transfer recording test, the thermal transfer ink was poor in acceptability and was not suitable for practical use. There was no result.

In Comparative Example 2, sticking and scum occurred during thermal recording because an overcoat layer for thermal transfer image-receiving paper was provided. In particular, in the case of high energy (black printing), sticking was remarkable, and whitening occurred in printing, which was not practical. On the other hand, at the time of thermal transfer recording, the coating amount of the overcoat layer was small, so that sufficient thermal transfer ink receptivity could not be obtained, resulting in printing chipping of a thin line portion. Therefore, if the coating amount of the overcoat layer is increased, the thermal transfer recording characteristics can be set to a level that does not hinder practical use. However, in this case, sensitivity decrease, sticking, and print residue increase during thermal recording. That is, it is not possible to satisfy both the characteristics of the thermal recording and the thermal transfer recording only by increasing or decreasing the coating amount of the overcoat layer for the thermal transfer image receiving paper.

[0074]

The thermal recording medium of the present invention can perform recording without sticking, print residue and the like during thermal recording, and has extremely excellent dot reproducibility. Also in thermal transfer recording, ink receptivity is good and dot reproducibility is extremely excellent.

Claims (8)

[Claims] 1. A support comprising, on a support, two or more electron-donating dye precursors which form colors different from each other, and one or more electron-accepting developers which form the dye precursors upon heating. In a multicolor thermosensitive recording medium provided with a thermosensitive recording layer containing,
A multicolor heat-sensitive recording medium, comprising an overcoat layer containing polyolefin-based resin particles on the heat-sensitive recording layer. 2. The thermosensitive recording medium according to claim 1, wherein said thermosensitive recording layer is a single layer. 3. A color-developing layer formed by polymerizing a compound having an unsaturated hydrocarbon bond on at least one of the electron-donating dye precursors. The heat-sensitive recording medium according to claim 1. 4. The multicolor heat-sensitive recording medium according to claim 1, wherein said polyolefin resin particles have an average particle size of 1 to 20 μm. 5. The polyolefin-based resin particles are low-density polyolefin resin particles.
4. The multicolor heat-sensitive recording medium according to any one of items 3 to 3. 6. The method according to claim 1, wherein the polyolefin resin is vinyl acetate copolymer resin particles.
The multicolor thermosensitive recording medium according to the above. 7. The multicolor heat-sensitive recording medium according to claim 1, wherein the solid content of the polyolefin-based resin particles in the overcoat layer is 5 to 90% by mass. 8. The coating amount of the overcoat layer is 3 g / m.
4. The multicolor heat-sensitive recording medium according to claim 1, wherein the number is ² or less.