JPH06227150A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide thermal recording material, by which image excellent in thermal responsiveness and having absorption in infrared region is obtained. CONSTITUTION:The thermal recording material concerned essentially consists of three components respectively made of specified compounds as dye precursor, developer made of salicylic acid derivatives or its metal salt and sensitizer made of aliphatic amide compound under the condition that the thermal recording material contains agglomerated particles produced by agglomerating the above-mentioned three components with anion-based dispersant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material which is excellent in thermal responsiveness and can be applied to an optical reading device to detect in the infrared region. is there.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally has a heat-sensitive recording layer containing a colorless or light-colored dye precursor and a color developer which reacts upon heating to develop the color of the dye precursor. When provided with a heating head, a heating pen, a laser beam, etc., a dye precursor and a developer react instantaneously to obtain a recorded image. JP-B-43-4160
It is disclosed in Japanese Patent Publication No. 45-14039. Such a heat-sensitive recording material has the advantages that recording can be obtained with a relatively simple device, that maintenance is easy, and that noise is not generated, and measurement recorders, facsimiles, printers, computer terminals, It is used in a wide range of fields such as labels and ticket vending machines. In particular, in the field of facsimiles, the demand for heat-sensitive systems has increased significantly, and along with this, there have been advances in speeding up to reduce transmission costs and energy saving to reduce the price due to downsizing of facsimiles. In response to such high speed and low energy of the facsimile, there has been a demand for higher sensitivity of the thermal recording material.

Since a high-speed facsimile sends and receives an A4 standard document in a few seconds to 20 seconds, the current flowing in the thermal head of the facsimile is repeated for a very short time of a few milliseconds or less, which is caused. The heat energy is transferred to the heat-sensitive recording sheet to cause an image forming reaction. In order to perform the image forming reaction with the thermal energy transferred in such a short time, it is necessary that the thermal recording material has excellent thermal responsiveness. In order to improve the thermal response, the compatibility between the dye precursor and the color developer must be improved. Sensitizers are used as mediators of this compatibility. The sensitizer has a function of accelerating the coloring reaction by dissolving or enclosing the dye precursor and the developer in the vicinity when the sensitizer is melted by the transferred thermal energy.

In recent years, there has been adopted a method for increasing the sensitivity of a heat-sensitive recording material by increasing the thermal response of this sensitizer. Examples of the sensitizer include, for example, JP-A-58.
-87094, naphthol derivatives, JP-A-57-64592, naphthoic acid derivatives, JP-A-58-112788, benzoic acid ester derivatives, JP-A-60-122193. , Parabenzylbiphenyl, JP-A-60-56588, and diphenoxyethanes, JP-A-61-2428.
In JP-A-84, sulfides and the like can be mentioned.

On the other hand, with the development of the information processing industry, the automation of offices is progressing, and the rationalization of office work is promoted. And as a way of rationalization, OC
R and OMR devices and bar code management have become widespread, and in general companies, OCR devices are used for main order slips, sales slips, shipping slips, purchase slips, input / output slips, etc.
It has become necessary to provide a slip suitable for OMR devices, bar code printing and reading. Also, in fields related to money such as payment slips of financial institutions, airline tickets, tickets, checks, securities, credit cards, bank cards, prepaid cards (prepayment cards), at the same time as recording information, forgery prevention or The advent of an optically readable thermosensitive recording material has been desired for the purpose of authenticity discrimination.

[0006]

As described above, in the conventional thermal recording material, the thermal responsiveness, which was not obtained, and the color-developed image was 500, using an optical reader.
It is an object of the present invention to provide a heat-sensitive recording material capable of absorbing in the infrared region having a wavelength of ˜1500 nm.

[0007]

As a result of earnest studies, the inventors of the present invention have excellent thermal responsiveness and obtained a color image of 5%.
The present invention provides a heat-sensitive recording material having absorptivity in the infrared region having a wavelength of 00 to 1500 nm. That is, the heat-sensitive recording material provided by the present invention is a heat-sensitive recording material containing a normally colorless to light-colored dye precursor and a developer that reacts when heated to develop the color of the dye precursor. At least one or more salicylic acid derivatives or metal salts thereof represented by Chemical Formula 3 (general formula 1), the sensitizer is an aliphatic amide compound having a molecular number of carbon atoms of 18 or more, and the dye precursor is chemical formula 4 (general formula 1). 2) comprising the compound represented by the formula (2), containing the dye precursor, the developer, and the sensitizer as essential components, and containing aggregating particles for heat-sensitive recording obtained by aggregating with a cationic dispersant. It is characterized by becoming.

[0008]

[Chemical 3] (In the formula, X ₁ and X ₂ represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group or a halogen atom, and R represents an alkyl group, an alkenyl group, an aralkyl group or an aryl group.)

[0009]

[Chemical 4] Here, R ₁ , R ₂ , R ₃ and R ₄ are each a lower aliphatic alkyl group such as methyl, ethyl and propyl; a lower aliphatic haloalkyl group such as chloromethyl and bromomethyl; a benzyl group or a substituted benzyl group ( A group that does not give an aqueous solution as a substituent); a phenyl group or a substituted phenyl group (a group that does not give an aqueous solution as a substituent). X is a hydrogen atom; a lower aliphatic alkyl group such as methyl, ethyl and propyl; a lower aliphatic alkoxyl group such as methoxy and ethoxy; a halogen atom such as chlorine and bromine; a haloalkyl group such as chloromethyl and trifluoromethyl; An alkylamino group such as methylamino, ethylamino, dimethylamino and diethylamino; a phenoxy group; a nitro group; and a lower aliphatic alkylthio group such as methylthio and ethylthio. n is 1-2.

Specific examples of the salicylic acid derivative represented by the general formula 1 of the present invention or a metal salt thereof include, for example, those shown below, but the present invention is not limited thereto. 3-butyloxysalicylic acid, 3-pentyloxysalicylic acid, 3-hexyloxysalicylic acid, 3
-Cyclohexyloxysalicylic acid, 3-octyloxysalicylic acid, 3-decyloxysalicylic acid, 3-dodecyloxysalicylic acid, 3-tetradecyloxysalicylic acid, 3-hexadecyloxysalicylic acid, 3-octadecyloxysalicylic acid, 4-butyloxysalicylic acid, 4 -Pentyloxysalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid,
4-octyloxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-tetradecyloxysalicylic acid, 4-hexadecyloxysalicylic acid, 4-octadecyloxysalicylic acid, 5-butyloxysalicylic acid, 5-pentyloxysalicylic acid, 5
-Hexyloxysalicylic acid, 5-cyclohexyloxysalicylic acid, 5-octyloxysalicylic acid, 5-decyloxysalicylic acid, 5-dodecyloxysalicylic acid, 5-tetradecyloxysalicylic acid, 5-hexadecyloxysalicylic acid, 5-octadecyloxysalicylic acid,

6-butyloxysalicylic acid, 6-pentyloxysalicylic acid, 6-hexyloxysalicylic acid,
6-cyclohexyloxysalicylic acid, 6-octyloxysalicylic acid, 6-decyloxysalicylic acid, 6-dodecyloxysalicylic acid, 6-tetradecyloxysalicylic acid, 6-hexadecyloxysalicylic acid, 6-octadecyloxysalicylic acid, 5-hexanoylsalicylic acid, 5-octanoylsalicylic acid, 3-hexanoyloxysalicylic acid, 3-octanoyloxysalicylic acid,
3-decanoyloxysalicylic acid, 4-hexanoyloxysalicylic acid, 4-octanoyloxysalicylic acid,
4-decanoyloxysalicylic acid, 5-hexanoyloxysalicylic acid, 5-octanoyloxysalicylic acid,
5-decanoyloxysalicylic acid, 6-hexanoyloxysalicylic acid, 6-octanoyloxysalicylic acid,
6-decanoyloxysalicylic acid, 5-octanesulfonylsalicylic acid, 3-hexylaminosalicylic acid, 3-
Octylaminosalicylic acid, 3-decylaminosalicylic acid, 3-octadecylaminosalicylic acid, 4-hexylaminosalicylic acid, 4-octylaminosalicylic acid, 4
-Decylaminosalicylic acid, 4-dodecylaminosalicylic acid, 3-octanoylaminosalicylic acid, 3-decanoylaminosalicylic acid, 4-octanoylaminosalicylic acid, 3-decanoylaminosalicylic acid and the like.

In the metal salt of the salicylic acid derivative represented by the general formula 1 of the present invention, the metal salt is sodium,
It contains a monovalent metal salt such as potassium or lithium, but is preferably a sparingly water-soluble or water-insoluble divalent, trivalent or tetravalent metal salt, more preferably a divalent or trivalent metal salt. Is a metal salt of.

Specific examples of the divalent, trivalent or tetravalent metal salt include zinc, cadmium, mercury magnesium, calcium, barium, nickel, tin, gallium, chromium, copper molybdenum, tungsten, zirconium, strontium and manganese. The salts of cobalt, titanium, aluminum and iron can be mentioned, but the salts of zinc, calcium, barium, nickel, manganese, cobalt and aluminum are preferable. In particular, zinc salt is preferable.

The number of carbon atoms constituting the molecule according to the present invention is 1
As the aliphatic amide compound having 8 or more, the following chemical formulas 5-8
What is represented by is preferable.

[0015]

Embedded image R ₁ CONH ₂

[0016]

Embedded image R ₂ CONHR ₃

[0017]

[Chemical 7] R ₄ CONHR ₅ NHOCR ₄

[0018]

Embedded image R ₆ NHOCR ₇ CONHR ₆

In the above Chemical Formulas 5-8, R ₁ , R ₂ , R ₄ , R
₆ represents an alkyl group or an alkenyl group. R ₃ represents an alkyl group, an alkenyl group or a hydroxymethyl group.
R ₅ and R ₇ represent a divalent linking group.

Some specific examples of these compounds include stearic acid amide, N-hydroxymethylstearic acid amide, behenic acid amide, N-hydroxymethylbehenic acid amide, N-stearyl stearic acid amide, and ethylenebisstearin. Acid amide, hexamethylenebisoleic acid amide, butylenebisstearic acid amide, hexamethylenebisstearic acid amide, N, N '
-Dioleyl sebacic acid amide, N, N'-dioleyl adipic acid amide, N, N'-distearyl sebacic acid amide, N, N'-distearyl adipic acid amide, etc. are mentioned. These are used alone or as a mixture.

Specific examples of the dye precursor represented by the general formula 2 of the present invention include those listed below, but the present invention is not limited thereto. 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3
-(P-dimethylaminophenyl) phthalide, 3- {
1,1-di (1-ethyl-2-methylindole) ethylene} -3- (p-diethylaminophenyl) phthalide 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3- (P-Dipropylaminophenyl) phthalide, 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3- (p-dichloromethylaminophenyl) phthalide, 3- {1,1- Di (1-
Ethyl-2-methylindole) ethylene} -3- (p
-Dibromoethylaminophenyl) phthalide, 3- {
1,1-di (1-ethyl-2-methylindole) ethylene} -3- (p-dibenzylaminophenyl) phthalide, 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3- (p-diphenylaminophenyl) phthalide, 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3- (p-phenylaminophenyl) phthalide, 3- {1,1 -Di (1-ethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-methylphenyl) phthalide, 3- {1,1-di (1-ethyl-2-methylindole) Ethylene} -3- (4'-diethylaminophenyl-2'-ethylphenyl) phthalide, 3- {1,1-
Di (1-ethyl-2-methylindole) ethylene} −
3- (4′-diethylaminophenyl-2′-methoxyphenyl) phthalide, 3- {1,1-di (1-ethyl-
2-Methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-ethoxyphenyl) phthalide, 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3- (4 '-Diethylaminophenyl-2'-methylthiophenyl) phthalide, 3- {1,
1-di (1-ethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-ethylthiophenyl) phthalide, 3- {1,1-di (1-
Ethyl-2-methylindole) ethylene} -3-
(4′-diethylaminophenyl-2′-chloromethylphenyl) phthalide, 3- {1,1-di (1-ethyl-
2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-diethylphenyl) phthalide,

3- {1,1-di (1-methyl-2-methylindole) ethylene} -3- (p-dimethylaminophenyl) phthalide, 3- {1,1-di (1-methyl-)
2-Methylindole) ethylene} -3- (p-diethylaminophenyl) phthalide, 3- {1,1-di (1-
Methyl-2-methylindole) ethylene} -3- (p
-Dipropylaminophenyl) phthalide, 3- {1,1
-Di (1-methyl-2-methylindole) ethylene}
-3- (p-dichloromethylaminophenyl) phthalide, 3- {1,1-di (1-methyl-2-methylindole) ethylene} -3- (p-dibromoethylaminophenyl) phthalide, 3- {1 , 1-di (1-methyl-2)
-Methylindole) ethylene} -3- (p-dibenzylaminophenyl) phthalide, 3- {1,1-di (1-
Methyl-2-methylindole) ethylene} -3- (p
-Diphenylaminophenyl) phthalide, 3- {1,1
-Di (1-methyl-2-methylindole) ethylene}
-3- (p-phenylaminophenyl) phthalide, 3-
{1,1-di (1-methyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2 '
-Methylphenyl) phthalide, 3- {1,1-di (1-
Methyl-2-methylindole) ethylene} -3-
(4′-Diethylaminophenyl-2′-tylphenyl) phthalide, 3- {1,1-di (1-methyl-2-methylindole) ethylene} -3- (4′-diethylaminophenyl-2′-methoxyphenyl) Phthalide, 3
-{1,1-di (1-methyl-2-methylindole)
Ethylene} -3- (4'-diethylaminophenyl-
2'-ethoxyphenyl) phthalide, 3- {1,1-di (1-methyl-2-methylindole) ethylene} -3
-(4'-diethylaminophenyl-2'-methylthiophenyl) phthalide, 3- {1,1-di (1-methyl-
2-Methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-ethylthiophenyl) phthalide, 3- {1,1-di (1-methyl-2-methylindole) ethylene} -3- ( 4'-diethylaminophenyl-2'-chloromethylphenyl) phthalide, 3- {
1,1-di (1-methyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-
Diethylphenyl) phthalide,

3- {1,1-di (1-propyl-2-methylindole) ethylene} -3- (p-dimethylaminophenyl) phthalide, 3- {1,1-di (1-propyl-2-) Methylindole) ethylene} -3- (p-diethylaminophenyl) phthalide, 3- {1,1-di (1-propyl-2-methylindole) ethylene}-
3- (p-dipropylaminophenyl) phthalide, 3-
{1,1-di (1-propyl-2-methylindole)
Ethylene} -3- (p-dichloromethylaminophenyl) phthalide, 3- {1,1-di (1-propyl-2-
Methylindole) ethylene} -3- (p-dibromoethylaminophenyl) phthalide, 3- {1,1-di (1
-Propyl-2-methylindole) ethylene} -3-
(P-dibenzylaminophenyl) phthalide, 3- {
1,1-di (1-propyl-2-methylindole) ethylene} -3- (p-diphenylaminophenyl) phthalide, 3- {1,1-di (1-propyl-2-methylindole) ethylene}- 3- (p-phenylaminophenyl) phthalide, 3- {1,1-di (1-propyl-2)
-Methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-methylphenyl) phthalide,
3- {1,1-di (1-propyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-tylphenyl) phthalide, 3- {1,1-di (1-propyl- 2-Methylindole) ethylene} −
3- (4'-diethylaminophenyl-2'-methoxyphenyl) phthalide, 3- {1,1-di (1-propyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'- Ethoxyphenyl) phthalide, 3- {1,1-di (1-propyl-2-methylindole) ethylene} -3- (4′-diethylaminophenyl-2′-methylthiophenyl) phthalide, 3- {
1,1-di (1-propyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2 '
-Ethylthiophenyl) phthalide, 3- {1,1-di (1-propyl-2-methylindole) ethylene}-
3- (4'-diethylaminophenyl-2'-chloromethylphenyl) phthalide, 3- {1,1-di (1-propyl-2-methylindole) ethylene} -3- (4 '
-Diethylaminophenyl-2'-diethylphenyl)
Phthalide,

3- {1,1-di (1-chloromethyl-2)
-Methylindole) ethylene} -3- (p-dimethylaminophenyl) phthalide, 3- {1,1-di (1-chloromethyl-2-methylindole) ethylene} -3-
(P-Diethylaminophenyl) phthalide, 3- {1,
1-di (1-chloromethyl-2-methylindole) ethylene} -3- (p-dipropylaminophenyl) phthalide, 3- {1,1-di (1-chloromethyl-2-methylindole) ethylene} -3- (p-dichloromethylaminophenyl) phthalide, 3- {1,1-di (1-chloromethyl-2-methylindole) ethylene} -3-
(P-dibromoethylaminophenyl) phthalide, 3-
{1,1-di (1-chloromethyl-2-methylindole) ethylene} -3- (p-dibenzylaminophenyl) phthalide, 3- {1,1-di (1-chloromethyl-
2-Methylindole) ethylene} -3- (p-diphenylaminophenyl) phthalide, 3- {1,1-di (1
-Chloromethyl-2-methylindole) ethylene}-
3- (p-phenylaminophenyl) phthalide, 3-
{1,1-di (1-chloromethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-methylphenyl) phthalide, 3- {1,1-di (1-chloromethyl) 2-Methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-tylphenyl) phthalide, 3- {1,1-di (1-chloromethyl-2-methylindole) ethylene} -3-
(4'-Diethylaminophenyl-2'-methoxyphenyl) phthalide, 3- {1,1-di (1-chloromethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-ethoxy Phenyl) phthalide, 3- {1,1-di (1-chloromethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-methylthiophenyl) phthalide, 3
-{1,1-di (1-chloromethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-ethylthiophenyl) phthalide, 3- {1,
1-di (1-chloromethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2 '
-Chloromethylphenyl) phthalide, 3- {1,1-di (1-chloromethyl-2-methylindole) ethylene} -3- (4'-diethylaminophenyl-2'-diethylphenyl) phthalide and the like.

The aggregate particles for heat-sensitive recording provided by the present invention have an average particle diameter of 2 to 30 μm. The average particle size is preferably 3 to 20 μm, more preferably 5 to 10 μm.
belongs to.

Regarding the agglomerated particles for heat-sensitive recording of the present invention,
The mixing ratio of the three components of the dye precursor, the color developer, and the sensitizer is 50 to 500 parts by weight of the color developer and the sensitizer with respect to 100 parts by weight of the dye precursor. Preferably, it is 100 to 300 parts by weight. Here, when the amount of each of the developer and the sensitizer is less than 50 parts by weight, when the unreacted product of the dye precursor exceeds 500 parts by weight, the unreacted product of the developer remains in a large amount. It is an economy.

The heat-sensitive recording material of the present invention will be specifically described below. The agglomerated particles for heat-sensitive recording of the present invention have three essential components, which are a dye precursor, a color developer and a sensitizer, as an essential component, and have an average particle diameter of 2 to 30 μm, preferably 3 to 20.
μm, and more preferably 5 to 10 μm,
Each of the three components was previously monodispersed or codispersed (dye precursor-
A sensitizer or a developer-sensitizer combination) having an average particle size of 0.1 to 0.5 μm is used. Normally,
It is considered that the smaller these three components are, the higher the sensitivity becomes. However, the base material for heat-sensitive recording is not completely smoothed on its surface, and irregularities due to pulp fibers are observed. Under the present circumstances, the finely dispersed particles enter the uneven portion of the pulp fiber, and the advantage of miniaturization is not fully utilized.

Since the aggregative particles for heat-sensitive recording of the present invention prevent the above-mentioned pulp fibers from entering the uneven portion and are uniformly arranged on the surface of the substrate, high sensitivity is achieved. Further, the agglomerated particles have the advantage that when the heat of the thermal head is transferred to the agglomerated particles themselves, the color is extremely efficiently developed because the three finely dispersed components are in close proximity.

Aggregate particles for heat-sensitive recording have an average particle diameter of 2 to 30.
μm, preferably 3 to 20 μm, more preferably 5 to
It is 10 μm. It depends on the coating thickness of the thermosensitive recording layer. When the agglomerated particles for heat-sensitive recording have a particle diameter equal to or larger than the coating layer thickness, the agglomerated particles are exposed from the coating layer, resulting in poor surface smoothness and pressure fog. On the other hand, if the average particle size is less than 2 μm, the effect cannot be sufficiently exhibited.

The agglomerated particles for heat-sensitive recording of the present invention are obtained by using a cationic surfactant or a cationic polymer to agglomerate a mixture of three components dispersed in advance with an anionic dispersant. Examples of the cationic surfactant include amine salts, quaternary ammonium salts, phosphonium salts, sulfonium salts and the like. Further, as the cationic polymer, aminoalkyl methacrylate and its acrylamide copolymer polyvinylpyridinium halide, polydiallylammonium halide, polyaminomethylacrylamide, polyvinylimidazoline, polyacrylamide Mannich modified product, polyethyleneimine polydiallylamine, polypyridinium halide chitosan, Examples thereof include cationized starch, cationized cellulose, cationized polyvinyl alcohol, ionene-based condensate, epoxyamine-based condensate, cationized polymethacrylic acid ester resin, and alkylenediamine-epichlorohydrin polycondensate.

In addition to the dye precursors used in the present invention, the following dye precursors can be used in combination. (1) Triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- ( p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-)
Yl) -6-Dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide 3,3-bis (2-phenylindol-3-yl) -5- Dimethylaminophthalide, 3-p-
Dimethylaminophenyl-3- (1-methylpyrrole-
2-yl) -6-dimethylaminophthalide and the like (2) diphenylmethane compound 4,4′-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-halophenylleuco auramine, 2,4,5-trichlorophenyl Leuco auramine etc.

(3) Xanthene compound Rhodamine B anilinolactam, Rhodamine B p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3- Diethylamino-7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3 -Diethylamino-7
-(2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N
-Ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6- Methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilinofluorane,
3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-propyl) amino-6-
Methyl-7-anilinofluorane, 3- (N-ethyl-
N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N
-Ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluorane and the like.

(4) Thiazine type compounds benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue and the like.

(5) Spiro compounds 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3 -Methoxybenzo) spiropyran, 3-propylspirobenzopyran and the like can be mentioned, and these can be used alone or in combination of two or more kinds.

In addition to the color developer used in the present invention, the following color developers can be used in combination. p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-
4'-methyldiphenyl sulfone, 4-hydroxy-
4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenyl sulfone, 1,1-bis (p-hydroxyphenylpropane, 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) butane, 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, 13-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'-dihydroxydiphenyl ether, 4,4 '
-Dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfone, 3,
3'-diallyl-4,4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate 2,2-bis (4 -Hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-t-
Butyl-5-methylphenol), bis (3-allyl-
4-hydroxyphenyl) sulfone, 4-hydroxy-4′-isopropyloxydiphenyl sulfone,
3,4-Dihydroxy-4′-methyldiphenylsulfone, benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, dimethyl 4-hydroxyphthalate, gallic acid Examples thereof include benzyl acid salt, stearyl gallate, salicylanilide, and 5-chlorosalicylanilide.

In addition to the sensitizer used in the present invention, the following sensitizers can be used in combination. 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 and 4-allyloxybiphenyl, 1,2-bis (3-methyl) Polyether compounds such as phenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, di (p-fluorobenzyl) oxalate, etc. Carbonic acid or oxalic acid diester derivative of These sensitizers can be used alone or in combination of two or more.

In addition, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin and the like are used as pigments in the heat-sensitive recording layer. . Further, for the purpose of preventing head wear and sticking, higher fatty acid metal salts such as zinc stearate and calcium stearate, paraffin, oxidized paraffin,
Waxes such as polyethylene, polyethylene oxide, stearic acid amide, castor wax, etc., dispersant such as sodium dioctyl sulfosuccinate, UV absorbers such as benzophenone type and benzotriazole type, surfactant, fluorescent dye, etc. are required. Is added according to.

As the adhesive used for the heat-sensitive recording layer,
Various commonly used adhesives can be used. For example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol polyacrylic acid soda, acrylic acid amide /
Acrylic acid ester copolymer Acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene /
Water-soluble adhesives such as alkali salts of maleic anhydride copolymers, alkali salts of ethylene / maleic anhydride copolymers, polyvinyl acetate, polyurethane, polyacrylic acid esters, styrene / butadiene copolymers, acrylonitrile / butadiene copolymers Examples thereof include polymers and latexes of methyl acrylate / butadiene copolymer ethylene / vinyl acetate copolymer and the like. Paper is mainly used as the substrate used in the present invention, but a non-woven fabric, a plastic film,
A synthetic paper, a metal foil or the like, a sheet obtained by smearing a pigment or the like on these, or a composite sheet obtained by combining these may be arbitrarily used.

Further, an undercoat layer coated with an inorganic pigment or an organic pigment on the above-mentioned base material may be used. The agglomerated particles for heat-sensitive recording used in the heat-sensitive recording material of the present invention can be used for partial printing using a printing machine by making them into ink.

[0040]

The heat-sensitive recording material of the present invention is a heat-sensitive recording material containing a colorless or light-colored dye precursor and a color-developing agent which reacts when heated to develop the color of the dye precursor. 1 or more of salicylic acid derivative or metal salt thereof represented by 1, the sensitizer is an aliphatic amide compound having a molecular number of carbon atoms of 18 or more, the dye precursor is composed of a compound represented by the general formula 2, It contains agglomerated particles for heat-sensitive recording which are composed of three components of a dye precursor, the color developer and the sensitizer as essential components and are agglomerated by a cationic dispersant. By using the monodispersed or co-dispersed fine particles of each of these three components in agglomerated form, the heat of the thermal head is efficiently transferred without the agglomerated particles entering into the uneven portion of the pulp fiber of the base material. Therefore, a highly sensitive heat-sensitive recording material can be obtained. Further, the aggregated particles can be made highly sensitive because the dye precursor and the fine particles of the color developer are close to each other. Further, the agglomerated particles have a color development image of 500 to 15 obtained by using a specific dye precursor.
Since it has absorption in the infrared region of wavelength 00, it can be used for various purposes for the purpose of preventing forgery or discriminating authenticity. For the above reasons, the heat-sensitive recording material of the present invention has an action not found in the conventional techniques.

[0041]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 1.3 Dispersion of Components A mixture having the following composition was ground and dispersed by a sand mill until the average particle diameter became about 0.2 μm. Here, anion-modified polyvinyl alcohol was used as the anionic dispersant. [Liquid A] Dispersion of Dye Precursor 3- {1,1-di (1-ethyl-2-methylindole) ethylene} -3- (p-diethylaminophenyl) phthalide 60 parts 3-dibutylamino-6-methyl- 7-anilinofluoran 40 parts 10% polyvinyl alcohol aqueous solution 50 parts water 100 parts [solution B] developer-sensitizer co-dispersion zinc 4-octyloxysalicylate 150 parts stearic acid amide 150 parts 10% polyvinyl alcohol aqueous solution 150 parts water 300 parts

2.3 Agglomeration of Component 3 As a cationic dispersant, a 10% cationized polyvinyl alcohol aqueous solution was used, and the dispersions of liquid A and liquid B obtained in the above 1 were mixed in the following ratios to prepare three components. Consisting of 1
Aggregated particles of 0 μm were prepared. Liquid A (solid content of dye precursor: 100 parts) 250 parts Liquid B (solid content of developer and sensitizer: 150 parts each) 750 parts Cationic dispersant 200 parts

3. Preparation of heat-sensitive coating liquid Using the agglomerated particles having an average particle diameter of 10 μm obtained in 2 above, a heat-sensitive coating liquid was prepared with the following formulation. Aggregated particles (35%) 400 parts 40% zinc stearate 25 parts 10% polyvinyl alcohol aqueous solution 200 parts calcium carbonate 50 parts water 425 parts The coating solution thus prepared is applied to a base paper having a basis weight of 40 g / m ² and a Mayer bar. A thermosensitive recording material was obtained by applying a coating amount (solid content) of 6 g / m ² and drying and then treating with a super calendar.

Example 2 In the same manner as in Example 1 except that the zinc 4-octyloxysalicylate used in Example 1 was replaced by zinc 4-octanoylsalicylate, agglomerated particles consisting of three components were obtained. A thermal recording material was prepared.

Example 3 3- {1,1-di (1-ethyl-2) used in Example 1
-Methylindole) ethylene} -3- (p-diethylaminophenyl) phthalide instead of 3- {1,1-
Di (1-ethyl-2-methylindole) ethylene}-
3- (4-N-ethyl-N-phenylaminophenyl)
Aggregate particles consisting of three components were obtained in the same manner as in Example 1 except that phthalide was used to prepare a heat-sensitive recording material.

Example 4 Instead of the stearamide used in Example 1,
Aggregated particles consisting of three components were obtained in the same manner as in Example 1 except that N, N′-dioleyl sebacic acid amide was used.
A thermal recording material was prepared.

Comparative Example 1 2,2-bis (4-hydroxyphenyl) was used in place of the zinc 4-octyloxysalicylate used in Example 1.
A thermal recording material was prepared in the same manner as in Example 1 except that propane was used.

Comparative Example 2 A heat-sensitive coating liquid was prepared as follows using the dispersion liquid of the liquids A and B of Example 1 as it was. Solution A 83 parts Solution B 250 parts 40% Zinc stearate 25 parts 10% Polyvinyl alcohol aqueous solution 193 parts Calcium carbonate 50 parts Water 365 parts The coating solution thus prepared is applied to a base paper having a basis weight of 40 g / m ² and a Mayer bar. A thermosensitive recording material was obtained by applying a coating amount (solid content) of 6 g / m ² and drying and then treating with a super calendar.

Comparative Example 3 A thermosensitive recording material was prepared in the same manner as in Example 1 except that the stearic acid amide of Example 1 was replaced with 2-benzyldioxynaphthalene. .

Comparative Example 4 3- {1,1-di (1-ethyl-2) used in Example 1
-Methylindole) ethylene} -3- (p-diethylaminophenyl) phthalide was removed, and 3-dibutylamino-6-methyl-7-anilinofluorane alone was used instead of 3 components in the same manner as in Example 1. The following agglomerated particles were obtained to prepare a heat-sensitive recording material.

The thermal recording materials prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated as follows, and the evaluation results are shown in Table 1.

[Evaluation of color development characteristics] A printing test was conducted using a facsimile tester TH-PMD manufactured by Okura Electric. Using a thermal head with a dot density of 8 dots / mm and a head resistance of 185Ω, the voltage was applied at a head voltage of 12 V, pulse widths of 0.7 and 1.0 ms for printing, and the color density was determined by the Macbeth RD-918 type reflection densitometer. It was measured at.

[Evaluation of PSD Density] A Macbeth print contrast meter PCM-11 (C
Filter; 680-960nm), PSD
The concentration was measured. The PSD density is an index showing the degree of optical readability, and represents the relative density between the image portion and the background portion. The higher the value, the higher the optical readability, and is expressed by the following mathematical formula 1. Value.

[0054]

## EQU00001 ## PSD density = (Rw-Rp) / Rw Here, Rw represents the maximum reflectance of the background portion, and Rp represents the maximum reflectance of the image portion.

[0055]

[Table 1]

From the results shown in Table 1, the particles using the agglomerated particles of Examples 1 to 4 showed higher color development and PSD density than the particles using the dispersion of Comparative Example 2. Instead of the developer or sensitizer of Example 1, the developer of Comparative Example 1,
In Comparative Example 3 in which the sensitizer was used, both the color-forming property and the PSD concentration were low. The product using the dye precursor of Comparative Example 4 exhibited a particularly low PSD concentration.

Comparative Example 5 In the agglomeration of the three components according to Example 1, the amount of the 10% cationized polyvinyl alcohol aqueous solution used was increased,
Aggregated particles having an average particle diameter of 35 μm were prepared. The obtained aggregated particles were used and coated on a base paper having a basis weight of 40 g / m ^{2 with} a Mayer bar in the same manner as in Example 1. However, the coated layer surface after coating was not preferable when used as a heat-sensitive recording material, because graininess due to aggregated particles was observed.

[0058]

The heat-sensitive recording material of the present invention comprises a dye precursor,
A thermosensitive recording aggregating particle comprising three components of a color developer and a sensitizer, wherein each of the three components comprises a specific compound, and the aggregating particle is used. In addition, it is characterized by having an unprecedented thermal response and having absorptivity in the near infrared region.
As described above, the heat-sensitive recording material of the present invention has extremely high practical value.

Claims (2)

[Claims] 1. A thermosensitive recording material containing a normally colorless to light-colored dye precursor, a developer that reacts when heated to develop the dye precursor, and a sensitizer.
At least one salicylic acid derivative represented by (general formula 1) or a metal salt thereof, the sensitizer is an aliphatic amide compound having a molecular number of carbon atoms of 18 or more, and the dye precursor is chemical formula 2 (general formula 2). Consisting of the compound represented by the above, and the three components of the dye precursor, the color developer and the sensitizer as essential components,
A heat-sensitive recording material comprising heat-sensitive recording agglomerated particles obtained by aggregating with a cationic dispersant. [Chemical 1] (In the formula, X ₁ and X ₂ represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group or a halogen atom, and R represents an alkyl group, an alkenyl group, an aralkyl group or an aryl group.) Here, R ₁ , R ₂ , R ₃ and R ₄ are each a lower aliphatic alkyl group such as methyl, ethyl and propyl; a lower aliphatic haloalkyl group such as chloromethyl and bromomethyl; a benzyl group or a substituted benzyl group ( A group that does not give an aqueous solution as a substituent); a phenyl group or a substituted phenyl group (a group that does not give an aqueous solution as a substituent). X is a hydrogen atom; a lower aliphatic alkyl group such as methyl, ethyl and propyl; a lower aliphatic alkoxyl group such as methoxy and ethoxy; a halogen atom such as chlorine and bromine; a haloalkyl group such as chloromethyl and trifluoromethyl; An alkylamino group such as methylamino, ethylamino, dimethylamino and diethylamino; a phenoxy group; a nitro group; and a lower aliphatic alkylthio group such as methylthio and ethylthio. n is 1-2. 2. The thermal recording aggregating particles have an average particle diameter of 2 to 3.
The heat-sensitive recording material according to claim 1, which has a thickness of 0 μm.