JPH10157289A - Multicolor thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor thermal recording material having small skin fog and high whiteness with clarity of distinction between a blue or green image of low temperature color developing and a black image of high temperature color developing. SOLUTION: A thermal color developing layer provided on a support contains composite fine particles containing at least one type of polymer substance selected from polyurea and polyurethane, at least one type of black color developable dye precursor and at least one type of red or yellow color developable dye precursor, or fat least two types of composite fine particles containing at least one type of polymer substance selected from polyurea and polyurethane, and black color developable red or yellow color developable dye precursors, solid fine particles of blue or green color developable dye precursor, and developable compound for generating color developing reaction with the black color developable precursor, red or yellow color developable dye precursor, and blue or green color developable dye precursor by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor heat-sensitive recording material which develops blue or green and black depending on the conditions for applying heat from a thermal head. More specifically, the present invention relates to a multicolor heat-sensitive recording material having a clear distinction between a low-temperature blue or green image and a high-temperature black image and a low background fog and high whiteness. is there.

[0002]

2. Description of the Related Art Conventionally, a dye precursor, and a color developing reaction between the dye precursor and a color developing agent which is brought into contact with the color of the dye under heating to form a color therewith, are used to fuse both color forming substances by heating.
Thermal recording materials for obtaining a color image are widely known. Such heat-sensitive recording materials are relatively inexpensive,
Since the recording device is compact and easy to maintain, it is used in a wide range of fields as a recording medium for facsimile, word processor, various computers, and other uses.

[0003] With respect to the heat-sensitive recording material, the required quality is diversified with the expansion of its use. For example, there are demands for high sensitivity, image stabilization, multicolor recording, and the like. In particular, the multicolor recording means has the advantage that characters or figures to be emphasized can be displayed clearly and clearly with a different color tone from other parts, and the demand for practical use thereof has been increasing.

Attempts have been made to utilize the difference in heating temperature or the difference in heat energy as a multicolor recording system.
Various multicolor heat-sensitive recording materials have been proposed. In general, a multicolor heat-sensitive recording material is formed by sequentially laminating a high-temperature coloring layer and a low-temperature coloring layer that form different colors on a support, and these are roughly classified into a decoloring type and an additive type. Are divided into two types.

As the decolorable multicolor heat-sensitive recording material, for example, JP-B-50-17865 and JP-B-57-14 are disclosed.
As disclosed in JP-A-320-320 and JP-A-2-80287, only the low-temperature color-forming layer develops color by the low-temperature color-forming operation. This is a method in which a decoloring agent having a color effect acts and only the high-temperature coloring layer develops color. This method has the advantage that the color tone can be freely selected, but it is necessary to add a large amount of a decoloring agent in order to obtain a sufficient decoloring effect on the low-temperature coloring layer. Then, the action of the decoloring agent added in a large amount causes the recorded color-developed image to fade during long-term storage, or requires an extra amount of heat to melt the decoloring agent, so that an excessive load is imposed on the thermal head. However, it is not always satisfactory in terms of image recording reliability and recording sensitivity.

On the other hand, a color-added multicolor heat-sensitive recording material is
JP-B-49-27708, JP-B-51-1998
No. 9, JP-A-51-146239, and the like, a method of laminating two color-forming layers that develop different colors and applying different amounts of heat to obtain a multicolor that can be identified. It is. This method is suitable when the lower color layer is a black color system because the upper color layer develops color at low temperature, and the upper and lower color layers develop color at high temperature, and an image of a mixed color tone of both colors is obtained. ing. In addition-colored recording material, since no decoloring agent is used, there is an advantage that the recorded image has excellent long-term storage properties and can be manufactured relatively inexpensively.
Also, since no extra heat is required for melting the decoloring agent, there is an advantage that the high-temperature coloring layer can be colored with lower energy as compared with the decoloring type. However, when the heat is applied too much at the time of low-temperature coloring, the coloring of the high-temperature coloring layer is also partially mixed, so that the low-temperature coloring image is hardly sharpened, and the high-temperature coloring image and the low-temperature coloring material are not added. There has been a problem that image segmentation is not sufficient. JP-A-56-99697 describes a method in which two or more dye precursors having different coloring tones and different average particle diameters are mixed in the same layer. In addition, there is a problem that color mixing is inevitable, and the high-temperature coloring image and the low-temperature coloring image are poorly distinguished.

The application of microcapsules to heat-sensitive recording materials has been known for a long time.
No. 9-70 describes encapsulation of a solvent in a liquid state at normal temperature. An example in which a color-forming component is microencapsulated as a core substance is disclosed in JP-A-57-12.
No. 695 and JP-A-59-214691. Further, Japanese Patent Publication No. 4-4960 and Japanese Patent Application Laid-Open No. 4-101885 disclose a color-forming component that develops a color tone different from each other in a solvent and contain each of the components in two or more types of microcapsules having different glass transition temperatures. It is described that the color is multiplied by performing the above. However, it develops a different color 2
If microcapsules of more than one kind of dye precursor are separately microencapsulated, the coloring sensitivity of each of the dye precursors decreases, and it becomes difficult to classify the sensitivity, and therefore, there is a problem that mixing of the coloring tones is likely to occur. Further, when an oil-based liquid solution of a dye precursor is included in the microcapsules, there is a problem that the color development is likely to occur due to the destruction of the capsules due to pressure or frictional rubbing.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multicolor heat-sensitive recording material in which a heat-sensitive coloring layer which develops blue or green and black is provided on a support according to a difference in heating application conditions from a thermal head. Another object of the present invention is to provide a multicolor heat-sensitive recording material which has a clear distinction between a blue or green image which is colored at a low temperature and a black image which is colored at a high temperature, has less background fog, and has a high whiteness.

[0009]

The multicolor heat-sensitive recording material according to the present invention comprises a support and a heat-sensitive color-forming layer formed thereon, wherein the heat-sensitive color-forming layer comprises (1) polyurea and polyurethane. At least one polymer substance selected from the group consisting of:
At least one black chromogenic dye precursor and at least one
Composite fine particles comprising a kind of a red or yellow coloring dye precursor, (2) solid fine particles of a blue or green coloring dye precursor, and (3) the above black coloring dye precursor, red Or a yellow or green color developing dye precursor and a blue or green color developing dye precursor and a color developing compound which causes a color forming reaction when heated.

The multicolor heat-sensitive recording material according to the present invention has a support and a heat-sensitive color-forming layer formed thereon, wherein the heat-sensitive color-forming layer is at least one selected from (1) polyurea and polyurethane. Composite fine particles comprising at least one kind of polymer substance and at least one kind of black chromogenic dye precursor; (2)
(3) composite fine particles comprising at least one polymer substance selected from polyurea and polyurethane, and at least one red or yellow chromogenic dye precursor;
Solid fine particles of a blue or green chromogenic dye precursor,
(4) containing the above-mentioned black-based coloring dye precursor, red-based or yellow-based coloring precursor, blue-based or green-based coloring precursor, and a color-developing compound which causes a color-forming reaction when heated. It is characterized by the following.

In the multicolor heat-sensitive recording material of the present invention, the red or yellow chromogenic dye precursor is selected from the group consisting of 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluoran, 3-diethylamino-7,8
-Benzofluoran, 3-diethylamino-7-phenoxyfluoran, 3,3-bis (1-n-butyl-2-
(Methylindol-3-yl) phthalide, (N-ethyl-N-isoamyl) amino-7-phenoxyfluoran, and 3,6-dimethoxyfluoran.

In the multicolor heat-sensitive recording material of the present invention, at least one of the composite fine particles is preferably selected from the group consisting of (1) a black color-forming dye precursor, and (2) a red or yellow color-forming dye precursor. And at least one dye precursor and a polymer-forming material that forms at least one of polyurea and polyurethane by polymerization in a water-insoluble organic solvent having a boiling point of 100 ° C. or less. Is emulsified and dispersed in an aqueous medium, the emulsified dispersion is heated to volatilize and remove the organic solvent, and then the polymer-forming raw material is polymerized.

[0013] In the multicolor heat-sensitive recording material of the present invention, at least one of the composite fine particles uses a polymer-forming raw material that forms at least one of polyurea and polyurethane by polymerization as a solvent. Dye precursor, (2) a red or yellow chromogenic dye precursor, and a solution containing at least one dye precursor selected as a solute is emulsified and dispersed in an aqueous medium, and this emulsified dispersion is heated. Prepared by polymerizing the polymer-forming raw material.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The multicolor heat-sensitive recording material of the present invention comprises:
(1) At least one kind of polymer substance selected from polyurea and polyurethane, composite fine particles composed of a black chromogenic dye precursor, and at least one kind of polymer substance selected from polyurea and polyurethane and red or yellow type Two kinds of composite fine particles of composite fine particles comprising a color-forming dye precursor,
Or composite fine particles comprising at least one polymer selected from polyurea and polyurethane, a black-based coloring dye precursor and a red-based or yellow-based coloring dye precursor, and (2) a blue-based solid fine particle or A green-color-forming dye precursor and (3) a color-developing compound which, when heated, is brought into contact with the black, blue- or green-, red- or yellow-color-forming dye precursor to form a color when heated. A heat-sensitive coloring layer is provided on a sheet-like support. In this case, the low-temperature color tone is the color tone of the blue or green color-forming dye precursor present in the solid fine particle state, and the high temperature color tone is the blue or green color-forming dye precursor in the solid fine particle state. Although the color tone is a mixed color of a black-based coloring dye precursor and a red-based or yellow-based coloring dye precursor present in the composite fine particles, since the color mixture is additive, almost black color is formed.

The blue or green color-forming dye precursor in the form of solid fine particles is melted by heating from a thermal head and mixed with and comes into contact with a color developing compound to form a color. The color-forming start temperature is a eutectic point of the blue-based or green-based chromogenic dye precursor and the color-developing compound, and a sensitizer and the like described below. Lower. Usually, the eutectic point is 7 depending on the selection of the sensitizer and the like.
Adjust so that the temperature is from 0 ° C to 100 ° C. On the other hand, the coloring temperature of the dye precursor in the composite fine particles is set so as to be higher than the color development starting temperature of the blue or green coloring dye precursor existing in the solid fine particle state. The setting method is mainly performed by appropriately selecting the type of the polymer substance in the composite fine particles and appropriately adjusting the compounding ratio of the dye precursor and the polymer substance, and the particle diameter of the composite fine particles. it can.

The composite fine particles used in the multicolor heat-sensitive recording material of the present invention comprise at least one polymer selected from polyurea and polyurethane, and a dye precursor. It is considered that a molecular substance is mixed at a molecular level and exists in a solid solution state. The appearance of the composite fine particles is almost spherical when observed with an electron microscope, or is in the form of hemoglobin with a hollow in the middle, and when the cut cross section is observed, solid solids without voids and a large number of pores are observed in the cut cross section. Porous solids present,
Alternatively, it is a hollow solid having a hollow portion having a diameter of one fifth or more of the particle diameter.

Since the dye precursor in the composite fine particles used in the multicolor heat-sensitive recording material of the present invention is mixed at a molecular level in a polymer substance, the dye precursor in the form of solid fine particles existing alone is present. Compared to the body, there is almost no direct contact with the developer fine particles or the sensitizer fine particles in the thermosensitive coloring layer. For this reason, the coloring sensitivity can be reduced more than the blue or green coloring dye precursor in the form of solid fine particles sensitized by a decrease in melting point. It is considered that the distinction between the two color development sensitivities can be made clear because the above-described color development start temperature regulating action works. At the time of low-temperature coloring, only the blue or green coloring dye precursor in the form of solid fine particles develops a color, whereas at the time of high-temperature coloring, the dye precursor in the composite fine particles develops a color together with the dye precursor in the form of solid fine particles. In additive color mixing, pure black is black regardless of what color is mixed. However, the color tone of the black chromogenic dye precursor in the composite fine particles when the color is developed cannot be said to be pure black, and when mixed with other colors, the color tone is affected. When only composite fine particles containing a black coloring dye precursor are used, a black image that is colored at a high temperature because the color tone of the blue or green coloring dye precursor is mixed with the color tone of the black coloring dye precursor. Slightly bluish or greenish. For this reason, there is a tendency that the division from a blue or green image which is a low-temperature color is somewhat unclear. Either the composite fine particles containing the red or yellow chromogenic dye precursor together with the composite fine particles containing the black coloring dye precursor, or in the composite fine particles,
When a red or yellow chromogenic dye precursor is present together with a black chromogenic dye precursor, a vivid black color can be developed even in high-temperature printing, and a low-temperature blue or green image and a high-temperature black image can be displayed. The division can be clarified.

As the dye precursor used in the state of solid fine particles in the present invention, a leuco compound such as triarylmethane, diphenylmethane, spiropyran, thiazine, or fluoran can be preferably used.

In the present invention, the blue or green color-forming dye precursor which can be used in the form of solid fine particles includes blue, blue-green,
It develops a color tone such as green, for example, 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4- Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide, 3- (1-ethyl-2-methylindole -3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylamino Phenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-
Yl) -3- (2-n-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,6-bis (diphenylamino) fluoran, 3- (N-ethyl-
Nn-hexylamino) -7-anilinofluoran;
3-diethylamino-7-dibenzylaminofluoran, 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- (N-ethyl-N
-P-tolylamino) -7- (N-phenyl-N-methylamino) fluoran, 3- [p- (p-anilinoanilino) anilino] -6-methyl-7-chlorofluoran, and 3,6-bis ( Dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide and the like.

In the present invention, the blue or green coloring dye precursor is prepared by using water as a dispersion medium, a sand grinder,
Pulverized by various wet pulverizers such as an attritor, a ball mill, a cobo mill, and the like, and denatured polyvinyl alcohol such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, and sulfonated polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, and styrene-maleic anhydride copolymer. In addition to water-soluble synthetic polymer compounds such as coalesced salts and their derivatives, a surfactant and an antifoaming agent, if necessary, are dispersed in a dispersion medium to form a dispersion, and this dispersion is used as a coating for forming a thermosensitive coloring layer. Can be used. Alternatively, after dissolving the dye precursor in a solvent, the solution may be emulsified and dispersed in water using the water-soluble polymer as a stabilizer, and the solvent may be evaporated from the emulsion to form the dye precursor into solid fine particles. it can. In any case, the average particle diameter of the dispersed particles of the blue or green chromogenic dye precursor used in the form of solid fine particles is preferably 0.2 to 3.0 μm in order to obtain appropriate color sensitivity. More preferably, it is 0.3 to 1.0 μm.

As the dye precursor used in the composite fine particles in the present invention, a leuco compound such as a triarylmethane compound, a diphenylmethane compound, a spiropyran compound, a lactam compound or a fluoran compound can be preferably used.

The black color-forming dye precursors of the present invention include 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-diethylamino-7- (m-trifluoromethylanilino) fluoran, -(N-isoamyl-N
-Ethylamino) -7- (o-chloroanilino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-
2-tetrahydrofurfurylamino) -6-methyl-7
-Anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3-di-n
-Amylamino-6-methyl-7-anilinofluoran, 3- (N-isoamyl-N-ethylamino) -6
Methyl-7-anilinofluoran, 3- (Nn-hexyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3- [N- (3-ethoxypropyl) -N
-Ethylamino) -6-methyl-7-anilinofluoran, 3- [N- (3-ethoxypropyl) -N-methylamino) -6-methyl-7-anilinofluoran, 3-
Diethylamino-7- (2-chloroanilino) fluoran, 3-di-n-butylamino-7- (2-chloroanilino) fluoran, 3-diethylamino-6-methyl-
Examples thereof include 7-anilinofluoran and 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluoran.

In the present invention, among the above black color-forming dye precursors, 3-di-n-amylamino-6-methyl-7-anilinofluoran is preferable because it does not easily cause background fogging.

The red-based or yellow-based color-forming dye precursor in the present invention is one that develops a purple-red, red, or yellow color. 6-bis (diethylamino) fluoran-
γ-anilinolactam, 3,6-bis (diethylamino) fluoran-γ- (p-nitro) anilinolactam, 3,6-bis (diethylamino) fluoran-γ-
(O-chloro) anilinolactam, 3-dimethylamino-7-bromofluoran, 3-diethylaminofluoran, 3-diethylamino-6-methylfluoran, 3-
Diethylamino-7-methylfluoran, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluoran, 3-diethylamino-7,
8-benzofluoran, 3-diethylamino-6,8-
Dimethylfluoran, 3-diethylamino-7-ter
t-butylfluoran, 3- (N-ethyl-N-tolylamino) -7-methylfluoran, 3- (N-ethyl-
N-tolylamino) -7-ethylfluoran, 3- (N
-Ethyl-N-isobutylamino) -6-methyl-7-
Chlorofluorane, and 3- (N-ethyl-N-isoamylamino) -7,8-benzofluoran, 3-cyclohexylamino-6-chlorofluoran, 3-di-n
-Butylamino-6-methyl-7-bromofluoran,
Examples thereof include 3-di-n-butylamino-7,8-benzofluoran.

The red or yellow color-forming dye precursor further includes 3-tolylamino-7-methylfluoran,
3-tolylamino-7-ethylfluoran, 2- (N-
Acetylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-propionylanilino)
-3-methyl-6-di-n-butylaminofluoran,
2- (N-benzoylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-carbobutoxyanilino) -3-methyl-6-di-n-butylaminofluoran 2- (N-formylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N
-Benzylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-allylanilino) -3
-Methyl-6-di-n-butylaminofluoran, and 2- (N-methylanilino) -3-methyl-6-di-
n-butylaminofluoran, 3,3-bis (1-n-
Butyl-2-methylindol-3-yl) phthalide,
3,3-bis (1-ethyl-2-methylindole-3
-Yl) phthalide, 3,3-bis (1-n-octyl-
2-methylindol-3-yl) phthalide, 7- (N
-Ethyl-N-isoamylamino) -3-methyl-1-
Phenylspiro [(1,4-dihydrochromeno [2,3
-C] pyrazole) -4,3'-phthalide], 7- (N
-Ethyl-N-isoamylamino) -3-methyl-1-
p-methylphenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3′-phthalide], and 7- (N-ethyl-Nn-hexylamino) -3- Methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3 ′
-Phthalide], 3-diethylamino-7-phenoxyfluoran, 3-di-n-butylamino-7-phenoxyfluoran, 3-di-n-amylamino-7-phenoxyfluoran, 3- (N-ethyl- N-isoamyl) amino-7-phenoxyfluoran, 3,6-dimethoxyfluoran, 2- (4-dodecyloxy-3-methoxystyryl) quinoline and the like can be mentioned.

In particular, among these red or yellow coloring dye precursors, 3-diethylamino-6-methyl-
7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluorane, 3-diethylamino-7,8-benzofluoran, 3-diethylamino-7-phenoxyfluoran,
3,3-bis (1-n-butyl-2-methylindol-3-yl) phthalide, (N-ethyl-N-isoamyl) amino-7-phenoxyfluoran, 3,6-dimethoxyfluoran are blue Alternatively, a multicolor heat-sensitive recording material having a clear distinction between a green image and a black image can be obtained.

The polymer-forming raw material used for forming the composite fine particles in the present invention may be a polyvalent isocyanate compound alone, or a mixture of a polyvalent isocyanate compound and a polyol which reacts with the polyisocyanate compound, or a polyvalent isocyanate compound. It may be a polymer such as an adduct of an isocyanate compound and a polyol, a biuret form, an isocyanurate form, or the like.

Examples of the polyvalent isocyanate compound used as a polymer-forming raw material include m-phenylene diisocyanate, p-phenylene diisocyanate,
2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-
Diisocyanate, p-xylylene diisocyanate,
m-xylylene diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 5-isocyanato-1- (isocyanatomethyl) -1,3,3
-Trimethylcyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylenediisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4
-Diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1, Diisocyanates such as 4-diisocyanate; triisocyanates such as 4,4 ', 4 "-triphenylmethane triisocyanate and toluene-2,4,6-triisocyanate; 4,4'-dimethyldiphenylmethane-2,2' And tetraisocyanates such as 5,5'-tetraisocyanate.
As an adduct of a polyvalent isocyanate and a polyol,
For example, isocyanate prepolymers such as trimethylolpropane adduct of hexamethylene diisocyanate, trimethylolpropane adduct of 2,4-tolylenediisocyanate, trimethylolpropane adduct of xylylenediisocyanate, and hexanetriol adduct of tolylene diisocyanate are used. be able to. Polymers of polyisocyanate compounds, for example, biuret of hexamethylene diisocyanate, isocyanurate of hexamethylene diisocyanate, and the like can also be used as the polymer-forming raw material of the present invention.

As the polyol compound used for the polymer-forming raw material, for example, ethylene glycol,
3-propanediol, 1,4-butanediol, 1,
5-pentanediol, 1,6-hexanediol,
1,7-heptanediol, 1,8-octanediol, propylene glycol, 2,3-butanediol,
1,2-butanediol, 1,3-butanediol,
2,2-dimethyl-1,3-propanediol, 2,4
-Pentanediol, 2,5-hexanediol, 3-
Methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,6-trihydroxyhexane, phenylethylene glycol, 1,1,1-trimethylolpropane, hexanetriol, penta Aliphatic polyols such as erythritol and glycerin, 1,4
A condensation product of an alkylene oxide with an aromatic polyhydric alcohol such as -di (2-hydroxyethoxy) benzene or 1,3-di (2-hydroxyethoxy) benzene;
Xylylene glycol, m-xylylene glycol,
α, α'-dihydroxy-p-diisopropylbenzene, 4,4'-dihydroxydiphenylmethane, 2-
(P, p'-dihydroxydiphenylmethyl) benzyl alcohol, 4,4'-isopropylidenediphenol, 4,4'-dihydroxydiphenylsulfone, 4,
4'-dihydroxydiphenyl sulfide, 4,4'-
Ethylene oxide adducts of isopropylidene diphenol, propylene oxide adducts of 4,4'-isopropylidene diphenol, acrylates having a hydroxyl group in the molecule, such as 2-hydroxyacrylate, and the like.

Of course, the polyvalent isocyanate compound, the adduct of the polyvalent isocyanate and the polyol, and the polyol compound are not limited to the above compounds.
Moreover, you may use 2 or more types together as needed. In addition,
Among the polyvalent isocyanate compounds or adducts of the polyvalent isocyanate compound and the polyol compound used in the present invention, those having three or more isocyanate groups in the molecule are particularly preferable.

The weight ratio of the dye precursor to the polymer substance in the composite fine particles is preferably from 5 to 80% by weight based on the total weight of the composite fine particles from the viewpoint of color sensitivity. More preferably, it is 20 to 50% by weight.

At least one polymer selected from the group consisting of polyurea and polyurethane used in the present invention;
As a method for preparing composite fine particles comprising at least one dye precursor selected from a black coloring dye precursor and a red or yellow coloring dye precursor, for example, these dye precursors have a boiling point of 100 ° C. It is dissolved in the following low-boiling water-insoluble organic solvent, and a polymer-forming raw material, for example, only a polyvalent isocyanate compound, or a mixture of a polyvalent isocyanate and a polyol that reacts with the same, or the addition of a polyvalent isocyanate and a polyol , A polymer such as a biuret of a polyvalent isocyanate, an isocyanurate, and the like, and then emulsifying and dispersing the mixture in an aqueous medium in which a protective colloid substance such as polyvinyl alcohol is dissolved and contained.
If necessary, after mixing a reactive substance such as polyamine,
The organic solvent is volatilized and removed by heating the emulsified dispersion, and then polymerized by polymerizing the polymer-forming material, thereby forming composite fine particles composed of a dye precursor and a polymer substance. There is a way to do that.

In this method, in order to sufficiently volatilize and remove the organic solvent, the conditions are set experimentally in consideration of the type of the solvent, the emulsification and dispersion conditions, the mixing ratio of the dye precursor and the solvent, and the like. It is good. Generally, when a solvent having a boiling point of 50 ° C. or less is used, an open container is used, and the dispersion after emulsification and dispersion is heated at a temperature 5 to 10 ° C. lower than the boiling point of the solvent for 2 hours or more, more preferably 5 hours. By holding above
The organic solvent can be volatilized and removed. After removing the organic solvent, the dispersion is heated to 80 ° C. to polymerize the polymerized raw material.
The composite fine particles can be produced by heating to about 95 ° C. and maintaining the temperature at this temperature for 1 hour or more, more preferably 2 hours or more.

The organic solvent used for preparing the composite fine particles may have a boiling point of 100 ° C. or less, more preferably 80 ° C.
It is preferable that the content be the following or hydrophobic. For example, such low-boiling hydrophobic (water-insoluble) organic solvents include butyl chloride (boiling point 78 ° C.), ethylidene chloride (57 ° C.), propyl chloride (46 ° C.), and methylene chloride (42 ° C.). ,
It can be selected from ethyl acetate (77 ° C) and methyl acetate (57 ° C). Acetone (56 ° C.) and methanol (65 ° C.) are not preferable because they are compatible with water and the resulting emulsion may become unstable.

At least one polymer selected from the group consisting of polyurea and polyurethane used in the present invention;
Another method for preparing composite fine particles comprising at least one dye precursor selected from black coloring dye precursors and red or yellow coloring dye precursors is to form these dye precursors into a polymer. Polyisocyanate compound as a raw material, or a mixture of a polyvalent isocyanate and a polyol reacting with the polyisocyanate, or an adduct of a polyvalent isocyanate and a polyol, a biuret of a polyvalent isocyanate, or a polymer such as an isocyanurate. After dissolving, this solution is emulsified and dispersed in an aqueous medium containing a protective colloid substance such as polyvinyl alcohol, and, if necessary, a reactive substance such as polyamine is mixed, and then the emulsified dispersion is heated. Polymerizes the polymer-forming raw material to form a polymer, thereby forming a complex comprising a dye precursor and a polymer substance It can be produced by a method of forming fine particles. Since this method does not use a low-boiling-point solvent, it has the advantage of not requiring an evaporation step, and is also capable of obtaining composite fine particles having excellent separability.

In the present invention, the emulsifier (protective colloid agent) used in the preparation of the composite fine particles includes a water-soluble polymer used for dispersing the above-mentioned blue or green color-forming dye precursor in the form of solid fine particles. The same can be used. At the same time, a surfactant, an antifoaming agent and the like may be used. The amount of the emulsifier used in the preparation of the composite fine particles is not particularly limited, but is generally preferably 1 to 50% by weight based on the weight of the solid content of the composite fine particle dispersion.
More preferably, it is about 30% by weight.

In the present invention, the polyamine compound optionally used includes, for example, ethylenediamine, trimethylenediamine, tetramethylenediamine,
Pentamethylenediamine, hexamethylenediamine, p
-Phenylenediamine, m-phenylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, epoxy Examples include amine adducts of compounds. Also, within a range that does not impair the purpose of the present invention,
Other polymer substances may be included.

The composite fine particles used in the present invention may contain, if necessary, an ultraviolet absorber, an antioxidant, an oil-soluble fluorescent dye, a release agent, and the like, in addition to the dye precursor. . Such an additive substance is preferably solid at room temperature, but may be liquid. The black coloring dye precursor and the red or yellow coloring dye precursor may each be a mixture of two or more dye precursors.

The inclusion of an ultraviolet absorber in the composite fine particles used in the thermosensitive coloring layer of the present invention is preferred from the viewpoint of light resistance, and particularly, 2- (2-hydroxy-5-methylphenyl) -2H-benzotriazole. Benzotriazole-based UV absorbers such as these have an effect of improving not only the light resistance of a color image but also the color sensitivity, and can be preferably used. In addition, when polymerizing the composite fine particles, a tin compound, a polyamide compound, an epoxy compound, a polyamine compound, or the like may be used in combination as a reaction accelerator. still,
When a polyamine compound is used, it is preferable to use an aliphatic polyamine compound from the viewpoint that light resistance is not reduced.

The average particle size of the composite fine particles used in the present invention is 0.1 to 15 μm in consideration of the color sensitivity.
Is more preferable, and it is more preferable to adjust so as to be in a range of 0.3 to 6.0 μm. The smaller the average particle diameter is, the higher the color sensitivity becomes. However, if the average particle diameter is too small, it is not preferable because the sensitivity classification from the blue or green chromogenic dye precursor in the solid fine particle state becomes unclear.

In the present invention, the ratio of the black chromogenic dye precursor to the red or yellow chromogenic dye precursor is generally such that the red or yellow chromogenic dye precursor is added to 100 parts by weight of the black chromogenic dye precursor. The amount of the dye precursor is preferably 5 to 200 parts by weight, more preferably 10 to 100 parts by weight. The amount of the blue-based or green-based chromogenic dye precursor to be present in the form of solid fine particles is preferably 20 to 600 parts by weight, more preferably 50 to 300 parts by weight, per 100 parts by weight of the black-based chromogenic dye precursor. Parts by weight.

By using the composite fine particles of the present invention, it is possible to suppress background color development due to pressing force and the occurrence of background fogging when blank paper is stored for a long period of time. Decoloration due to oil or oil can also be significantly suppressed.

The color-developing compound used in the present invention is not particularly limited, but generally has the property of dissolving with an increase in temperature and has the above-mentioned black, red or yellow color.
It is selected from those having the property of contacting with a blue or green dye precursor to develop color. Representative color developing compounds include 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol,
4,4'-sec-butylidenediphenol, 4-phenylphenol, 4,4'-dihydroxydiphenylmethane, 4,4'-isopropylidenediphenol, 4,
4'-cyclohexylidene diphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane,
4,4'-dihydroxydiphenyl sulfide, 4,
4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-
Phenolic compounds such as hydroxy-4'-isopropoxydiphenyl sulfone and bis (3-allyl-4-hydroxyphenyl) sulfone can be mentioned.

Further, in the present invention, compounds that can be used as the color developing compound include 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate,
Phenolic compounds such as 4-sec-butyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, and 4,4'-dihydroxydiphenyl ether Or benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, Aromatic carboxylic acids such as 3,5-di-tert-butylsalicylic acid, and phenolic compounds, and organic acidic substances such as salts of aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum and calcium. But That.

In the present invention, it is preferable to use a diphenylsulfone derivative containing a hydroxyl group in the molecule as the color developing compound. For example, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, and bis (3-allyl-4-
(Hydroxyphenyl) sulfone. Such a color-developing compound has excellent properties in preserving a color image. This is presumed to be due to the strong electron-withdrawing property of the sulfone group of the color-developing compound. Also,
In order to form a color-developed image that is hardly decolored even when it comes in contact with oil or a plasticizer, 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane or N- (p -Toluenesulfonyl)
It is preferred to use -N'-phenylurea.

The color-developing compound is usually a total of 1 dye precursor.
It is preferably used in an amount of 100 to 700 parts by weight, more preferably 150 to 400 parts by weight, based on 00 parts by weight. Of course, if necessary, two or more types of color developing compounds can be used in combination.

In the present invention, an image stabilizer may be used mainly for improving the storability of the color recording image. Examples of such an image stabilizer include 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane and 1,1,3-tris (2-methyl-
4-hydroxy-5-tert-butylphenyl) butane, 1,1-bis (2-methyl-4-hydroxy-5-
tert-butylphenyl) butane, 4,4 ′-[1,
Phenolic compounds such as 4-phenylenebis (1-methylethylidene)] bisphenol and 4,4 '-[1,3-phenylenebis (1-methylethylidene)] bisphenol; 4-benzyloxyphenyl-4'
-(2-methyl-2,3-epoxypropyloxy) phenylsulfone, 4- (2-methyl-1,2-epoxyethyl) diphenylsulfone, and 4- (2-ethyl-1,2-epoxyethyl) diphenyl Epoxy compounds such as sulfones, and those containing at least one selected from isocyanuric acid compounds such as 1,3,5-tris (2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl) isocyanuric acid Can be used. Of course, the image stabilizer is not limited to these, and two or more compounds can be used in combination as needed.

In order to adjust the color sensitivity of the heat-sensitive coloring layer of the heat-sensitive recording material, a heat-fusible substance can be contained in the heat-sensitive coloring layer as a sensitizer. As the sensitizer, a compound conventionally known as a sensitizer for a thermosensitive recording material can be used. For example, parabenzyl biphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate can be used. , Adipic acid di-o-
Chlorobenzyl, 1,2-diphenoxyethane, 1,2
-Bis (3-methylphenoxy) ethane, bis-p-methylbenzyl oxalate, bis-p-chlorobenzyl oxalate, 1,2-bis (3,4-dimethylphenyl) ethane, 1,3-bis (2 -Naphthoxy) propane and the like. In particular, when bis-p-methylbenzyl oxalate and bis-p-chlorobenzyl oxalate are used as sensitizers, a sensitizing effect with less fogging can be obtained.

The color developing compound used in the present invention,
Additives such as an image stabilizer and a sensitizer are dispersed in water in the same manner as when a blue or green chromogenic dye precursor is used in the form of solid fine particles, to prepare a heat-sensitive chromogenic layer-forming paint. It can be mixed with this. Further, these additives may be dissolved in a solvent, and the resulting solution may be emulsified in water using a water-soluble polymer compound as an emulsifier. Furthermore, composite fine particles containing these compounds may be prepared in the same manner as the above-described composite fine particle preparation method, and may be contained in the thermosensitive coloring layer. Further, the image stabilizer and the sensitizer may be contained in the composite fine particles containing the dye precursor. In particular, the coloring sensitivity can be adjusted to a desired value by including a sensitizer in the composite fine particles together with the dye precursor.

In the present invention, a fine pigment having a high whiteness and an average particle diameter of 10 μm or less can be contained in the thermosensitive coloring layer in order to improve the whiteness of the thermosensitive coloring layer and the uniformity of the image. For example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface-treated calcium carbonate and silica Inorganic pigments and organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin and polystyrene resin can be used. Oil absorption is 50ml / 1 to prevent sticking to the thermal head and sticking.
It is preferred to use more than 00 g of pigment. The amount of the pigment is preferably such that the color density is not reduced, that is, 50% by weight or less based on the total solid content of the thermosensitive coloring layer.

In the present invention, an adhesive is used as another component material constituting the thermosensitive coloring layer, and a crosslinking agent, a wax, a metal soap, a colored dye, a colored pigment, a fluorescent dye and the like are used as necessary. be able to. Examples of the adhesive include polyvinyl alcohol and its derivatives, starch and its derivatives, cellulose derivatives such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, and acrylamide-acrylic acid ester. Water-soluble polymer materials such as coalesced, acrylamide-acrylate-methacrylate copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin and derivatives thereof, and , Polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-
Examples include emulsions such as vinyl acetate copolymers, and latexes of water-insoluble polymers such as styrene-butadiene copolymers and styrene-butadiene-acrylic copolymers.

Further, in order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for three-dimensionally curing the adhesive may be contained in the thermosensitive coloring layer. For example, aldehyde compounds such as glyoxal, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds, and ammonium persulfate and ferric chloride, and chloride Magnesium, sodium tetraborate, inorganic compounds such as potassium tetraborate or boric acid, boric acid triesters, at least one crosslinkable compound selected from boron-based polymers and the like with respect to the total solid weight of the thermosensitive coloring layer It is preferable to use it in the range of 1 to 10% by weight.

The wax added to the thermosensitive coloring layer includes paraffin wax, carnauba wax, microcrystalline wax, polyolefin wax,
And waxes such as polyethylene wax, and higher fatty acid amides such as stearic acid amide and ethylenebisstearic acid amide, higher fatty acid esters,
And derivatives thereof. In particular, when a methylolated fatty acid amide is added to the thermosensitive coloring layer, a sensitizing effect can be obtained without deteriorating the ground fog resistance.

Examples of the metal soap added to the thermosensitive coloring layer include higher fatty acid polyvalent metal salts such as zinc stearate,
Aluminum stearate, calcium stearate,
And zinc oleate. Including a colored dye and / or a colored pigment having a color tone that is complementary to the low-temperature color tone in the thermosensitive coloring layer is preferably used to adjust the tone of the recording material before printing. If necessary, various additives such as an oil repellent, an antifoaming agent, and a viscosity modifier can be added to the thermosensitive coloring layer as long as the effects of the present invention are not impaired.

There is no particular limitation on the type, shape, dimensions, etc. of the support material used in the present invention, and examples thereof include high quality paper (acid paper, neutral paper), medium paper, coated paper, art paper, and cast paper. In addition to coated paper, glassine paper, resin-laminated paper, polyolefin-based synthetic paper, synthetic fiber paper, nonwoven fabric, synthetic resin film, and the like, various transparent supports and the like can be appropriately selected and used.

In the present invention, in order to increase the added value of the multicolor heat-sensitive recording material, the multicolor heat-sensitive recording material can be further processed to obtain a heat-sensitive recording material having a higher function.
For example, an adhesive, rewet adhesive, delayed tack type adhesive, etc., can be applied to the back side to make adhesive paper, rewet adhesive paper, delayed tack paper, or magnetic processing to the back side. A thermosensitive recording material having a magnetically recordable layer can be obtained. In particular, adhesive processing,
The magnetically processed product is useful for applications such as a multicolor heat-sensitive label and a multicolor heat-sensitive magnetic ticket. In addition, a recording paper capable of performing double-sided recording can be provided by using the back surface thereof and imparting functions as thermal transfer paper, ink-jet paper, carbonless paper, electrostatic recording paper, and xerographic paper. Of course, a double-sided heat-sensitive recording material can also be used.

In the present invention, a protective layer can be provided on the thermosensitive coloring layer, and an undercoat layer can be provided below the thermosensitive coloring layer. As these additional layers, a protective layer and an undercoat layer which have been used for a conventionally known heat-sensitive recording material can be used. The protective layer and the undercoat layer are both composed mainly of a pigment and an adhesive. In particular, a lubricant such as polyolefin wax or zinc stearate is preferably added to the protective layer for the purpose of preventing sticking to the thermal head, and the protective layer may be composed of two or more layers. By providing a glossy protective layer, the added value of the product can be increased. By using a pigment having a high porosity, such as silica or calcined kaolin, for the undercoat layer, the coloring sensitivity of the thermosensitive coloring layer thereon can be increased. Including a plastic pigment, hollow particles, foam, or the like in the undercoat layer is also effective in improving the color sensitivity of the thermosensitive coloring layer formed thereon.

By using a release agent such as silicon for the protective layer, the heat-sensitive recording material of the present invention can be used as a linerless pressure-sensitive adhesive label. Further, a resin layer cured by ultraviolet rays or electron beams may be provided on the thermosensitive coloring layer or the protective layer. In the present invention, UV ink,
Printing can also be performed using flexo ink or the like. In this case, printing may be performed on any layer such as a heat-sensitive layer, a protective layer, an ultraviolet curable resin layer, and an electron beam curable resin layer.

The method for forming each of the above layers on the support includes known coating methods such as an air knife method, a blade method, a gravure method, a roll coater method, a spray method, a dip method, a bar method, and an extrusion method. Either may be used. Further, the thermosensitive coloring layer coating composition of the present invention can be partially printed and used by using a printing machine or the like. The coating material for the heat-sensitive coloring layer is provided on one surface of the support at 1 to 10 g / m ^2.
(Dry) to form a thermosensitive coloring layer. Further, a back layer can be provided for suppressing penetration of oil or plasticizer from the back surface of the recording material, or for controlling curl. Smoothing the thermosensitive coloring layer using a known smoothing method such as a super calender or a soft calender is effective in increasing the coloring sensitivity. The surface of the thermosensitive coloring layer may be treated by applying it to either a metal roll or an elastic roll of a calender.

[0060]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
Unless otherwise specified, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

Examples 1 to 6 and Comparative Example 1 Example 1 (1) Preparation of Dispersion of Composite Fine Particles Containing Black Color Developing Dye Precursor 3-Di-n-amylamino-6 as Black Color Developing Dye Precursor 10 parts of -methyl-7-anilinofluoran in 100 parts
Dissolved in 24 parts of dicyclohexylmethane-4,4′-diisocyanate heated to 35 ° C., cooled the solution to 35 ° C., and then 8% aqueous polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry, trade name: Gohsenol GM-14L) at the same temperature 25
0 parts gradually, using a homogenizer, and rotating at 8 rpm.
After emulsification and dispersion by stirring at 000 rpm, 100 parts of water was added to the emulsified dispersion to homogenize. The temperature of the emulsified dispersion was raised to 90 ° C., and a curing reaction was carried out for 10 hours to prepare a dispersion of black-color-forming dye precursor-containing composite fine particles having an average particle diameter of 1.3 μm. (2) Preparation of Dispersion of Composite Fine Particles Containing Red or Yellow Chromogenic Dye Precursor Dicyclohexyl obtained by heating 10 parts of 3-diethylamino-7-chlorofluorane as a red or yellow chromogenic dye precursor to 100 ° C. After dissolving in 24 parts of methane-4,4'-diisocyanate, the solution was cooled to 35 ° C., and then 8% polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry,
Trade name: Gohsenol GM-14L) The solution was gradually added to 250 parts of an aqueous solution, and the number of revolutions was 8,000 rp using a homogenizer.
After emulsifying and dispersing by stirring with m 2, 100 parts of water was added to the emulsified dispersion to homogenize. 90 ° C.
And a curing reaction was carried out for 10 hours to prepare a dispersion liquid of composite fine particles containing a red or yellow chromogenic dye precursor having an average particle diameter of 1.3 μm.

(3) a blue or green color-forming dye precursor,
Preparation of Solid Dispersion of Developing Compound and Sensitizer Blue- or Green-Based Chromogenic Dye Precursor 3- (1-Ethyl-2-methylindol-3-yl)
-3- (2-Methyl-4-diethylaminophenyl)-
4-azaphthalide color-developing compound 4,4'-isopropylidenediphenol sensitizer bis-p-methylbenzyl oxalate The above-mentioned blue or green color-developing dye precursor, color-developing compound,
And a sensitizer are separately mixed with polyvinyl alcohol at the following mixing ratio, and each mixture is separately separated using a vertical sand mill (manufactured by Imex Co., Ltd., sand grinder) so that the average particle diameter becomes 1.2 μm. Ground and dispersed. Component Amount (parts by weight) Precursor for blue or green color, dye or sensitizer 40 Polyvinyl alcohol 10% solution 40 (degree of polymerization 500, degree of saponification 90%) Water 20

(4) Preparation of Pigment Dispersion Silica (Mizukasil P527, oil absorption 190 ml / 100
g, manufactured by Mizusawa Chemical Industry Co., Ltd.) and sodium polyacrylate at the following mixing ratio, and this mixture was dispersed by a Cowles dispersing machine. Component Amount (parts by weight) Silica 30 0.7% sodium polyacrylate solution 70

Separately, an aqueous solution of polyvinyl alcohol (NM11Q, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a solid content of 10% was used as an adhesive solution, and an aqueous zinc stearate dispersion (Z- 7, Chukyo Yushi Co., Ltd.).

(5) Formation of Undercoat Layer The above pigment dispersion and adhesive liquid were mixed at a solid content of 85:
The coating solution was mixed on a high-quality paper (neutral paper) having a basis weight of 60 g / m ² using a Meyer bar.
g / m ² (dry) was applied to form an undercoat layer.

(6) Formation of a thermosensitive coloring layer A dispersion of the above-mentioned composite fine particles containing a black chromogenic dye precursor,
Dispersion of red or yellow chromogenic dye precursor-containing composite fine particles, blue or green chromogenic dye precursor dispersion, color developing compound dispersion, sensitizer dispersion, pigment dispersion, adhesive liquid ,
The lubricant dispersion has a solid content of 15: 15: 8: 25:
15: 15: 3: 5 to prepare a thermosensitive coloring layer coating solution. This coating solution was applied onto the previously formed undercoat layer using a Mayer bar at a coating amount (drying) of 5.0 g / m ² and dried to form a thermosensitive coloring layer. After that, a super calender was used to perform a smoothing treatment so that the Beck smoothness (JIS-P8119) of the heat-sensitive recording surface was 100 to 150 seconds, thereby producing a multicolor heat-sensitive recording material.

Example 2 Except that (N-ethyl-N-isoamyl) amino-7-phenoxyfluorane was used in place of 3-diethylamino-7-chlorofluorane as a red or yellow chromogenic dye precursor, A multicolor heat-sensitive recording material was produced in the same manner as in Example 1.

Example 3 Example 3 was repeated except that 3-diethylamino-7,8-benzofluorane was used in place of 3-diethylamino-7-chlorofluorane as a red or yellow chromogenic dye precursor. Similarly, a multicolor heat-sensitive recording material was produced.

Example 4 Example 1 was repeated except that 3-diethylamino-7-tert-butylfluorane was used instead of 3-diethylamino-7-chlorofluorane as a red or yellow chromogenic dye precursor. Similarly, a multicolor heat-sensitive recording material was produced.

Example 5 3-di-n-amylamino-6-methyl-7-anilinofluorane was used as a black chromogenic dye precursor in place of 3-di-n-amylamino-6-methyl-7-anilinofluoran.
A multicolor heat-sensitive recording material was produced in the same manner as in Example 1 except that di-n-butylamino-6-methyl-7-anilinofluoran was used.

Example 6 Example 6 was repeated except that a dispersion prepared by the following method was used as a dispersion of the composite fine particles containing the black chromogenic dye precursor and a dispersion of the composite fine particles containing the red or yellow chromogenic dye precursor. In the same manner as in Example 1, a multicolor heat-sensitive recording material was produced. (1) Preparation of Dispersion of Composite Fine Particles Containing Black Chromogenic Dye Precursor As a black chromogenic dye precursor, 10 parts of 3-di-n-amylamino-6-methyl-7-anilinofluoran were treated with 30 parts of methylene chloride. And an adduct of a 1: 3 molar ratio of trimethylolpropane and xylylenediisocyanate (trade name: Takenate D, manufactured by Takeda Pharmaceutical Co., Ltd.)
-110N, diluting solvent: ethyl acetate, concentration 75%) 12
The mixture was added to 250 parts of a 5% aqueous solution of polyvinyl alcohol (trade name: Gohsenol GM-14L, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and the mixture was rotated at 5,000 rpm using a homogenizer. After emulsification and dispersion by stirring, 100 parts of water was added to the emulsified dispersion to homogenize. The temperature of the emulsified dispersion was raised to 45 ° C., and stirring was continued for 7 hours to remove methylene chloride and ethyl acetate by evaporation. Thereafter, the temperature of the mixture was raised to 80 ° C.
After a curing reaction for 3 hours, the average particle diameter is 1.8 μm.
A dispersion of the black-color-forming dye precursor-containing composite fine particles was prepared.

(2) Preparation of Dispersion of Composite Fine Particles Containing Red or Yellow Chromogenic Dye Precursor As a red or yellow chromogenic dye precursor, 10 parts of 3-diethylamino-7-chlorofluorane and 30 parts of methylene chloride were used. And an adduct of trimethylolpropane and xylylenediisocyanate at a molar ratio of 1: 3 (Takeda Pharmaceutical Co., Ltd., trade name: Takenate D-110)
N, diluting solvent: ethyl acetate, concentration: 75%), 12 parts were added and mixed uniformly, and the mixture was mixed with 5% polyvinyl alcohol (trade name: Gohsenol GM, manufactured by Nippon Synthetic Chemical Industry).
-14 L) The mixture was gradually added to 250 parts of an aqueous solution, and emulsified and dispersed by stirring with a homogenizer at a rotation speed of 5000 rpm. Then, 100 parts of water was added to the emulsified dispersion to homogenize. The temperature of the emulsified dispersion was raised to 45 ° C., and stirring was continued for 7 hours to remove methylene chloride and ethyl acetate by evaporation. Thereafter, the temperature of the mixed liquid was raised to 80 ° C., and a curing reaction was performed for 3 hours to prepare a dispersion liquid of red or yellow color-forming dye precursor-containing composite fine particles having an average particle diameter of 1.8 μm.

Example 7 A dispersion of a black color-forming dye precursor and a composite fine particle containing a red or yellow color-forming dye precursor prepared by the following method, and a blue or green color forming property similar to that of Example 1. The solid content of the dye precursor dispersion, the color developing compound dispersion, the sensitizer dispersion, the pigment dispersion, the adhesive solution, and the lubricant dispersion is 30:
8: 25: 15: 15: 3: 5, and a multicolor thermosensitive recording paper was produced in the same manner as in Example 1 except that a thermosensitive coloring layer coating solution was prepared. (1) Preparation of Dispersion of Composite Particles Containing Black-Based Chromogenic Dye and Red or Yellow-Based Chromogenic Dye Precursor 3-Di-n-amylamino-6-methyl-7-aniline as a black-based chromogenic dye precursor 5 parts of linofluorane, 3-diethylamino- as a red or yellow chromogenic dye precursor
5 parts of 7-chlorofluorane was dissolved in 24 parts of dicyclohexylmethane-4,4'-diisocyanate heated to 100 ° C, and the solution was cooled to 35 ° C, and then 8% polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry) at the same temperature. (Trade name: Gohsenol GM-14L) was gradually added to 250 parts of an aqueous solution, and the mixture was emulsified and dispersed by stirring with a homogenizer at a rotation speed of 8000 rpm, and 100 parts of water was added to the emulsified dispersion to homogenize. The temperature of the emulsified dispersion was raised to 90 ° C., and a curing reaction was performed for 10 hours to obtain an average particle diameter of 1.3.
A μm dispersion of composite fine particles containing a black color-forming dye precursor and a red or yellow color-forming dye precursor was prepared.

COMPARATIVE EXAMPLE 1 A solid dispersion of a black chromogenic dye precursor, a solid dispersion of a red or yellow chromogenic dye precursor prepared by the following method, and blue or green chromogenic properties similar to those in Example 1. Dye precursor dispersion, color developing compound dispersion, sensitizer dispersion, pigment dispersion,
The solid content of the adhesive liquid and the lubricant dispersion is 5: 5: 8:
A multicolor thermosensitive recording paper was produced in the same manner as in Example 1 except that the composition was blended so as to be 25: 15: 15: 3: 5 to prepare a thermosensitive coloring layer coating solution. (1) Preparation of Solid Dispersion of Black Chromogenic Dye Precursor, Red or Yellow Chromogenic Dye Precursor Black Chromogenic Dye Precursor 3-Di-n-amylamino-6-methyl-7-anilino Fluoran Red or yellow chromogenic dye precursor 3-Diethylamino-7-chlorofluoran The above black chromogenic dye precursor, red or yellow chromogenic dye precursor are separately added to polyvinyl alcohol and the following mixing ratio , And each mixture was separately pulverized and dispersed using a vertical sand mill (manufactured by Imex Co., Ltd., sand grinder) so that the average particle diameter became 1.2 μm. Component Amount (parts by weight) Black coloring dye precursor, red or yellow coloring dye precursor 40 Polyvinyl alcohol 10% solution 40 (polymerization degree 500, saponification degree 90%) Water 20

Comparative Example 2 In the formation of the heat-sensitive layer in Example 1, a dispersion of the composite fine particles containing the black color-forming dye precursor, a dispersion of the composite fine particles containing the red or yellow color-forming dye precursor, blue or green The solid color mixing ratio of the system color-forming dye precursor dispersion, the color developing compound dispersion, the sensitizer dispersion, the pigment dispersion, the adhesive solution, and the lubricant dispersion is 30: 0: 8: 25: 15: 15. A multicolor heat-sensitive recording material was prepared in the same manner as in Example 1 except that the mixing ratio was 3: 5.

A test was performed on each of the multicolor heat-sensitive recording materials obtained by the above operation. Thermal recording was performed using a thermal printing tester TH-PMD (manufactured by Okura Electric Co., Ltd.) under the conditions of one line recording time: 5 msec, sub-scanning line density: 8 lines / mm, and applied energy per dot: 0.4 mJ. Were printed, and low-temperature coloring in low-temperature printing was performed. Separately, along with this printing, one thin line was printed under the conditions of one line recording time: 5 msec, sub-scanning line density: 8 lines / mm, and applied energy per dot: 1.5 mJ. Color development was performed.

The division of the two thin lines thus obtained is
It was visually evaluated according to the following evaluation criteria. Classification of coloring part ◎: Very clear classification ○: Very clear classification ×: Classification is unclear or not possible at all

In order to evaluate the background fog resistance,
After leaving the obtained multicolor heat-sensitive recording material in an environment of 40 ° C. and 90% RH for 24 hours, its whiteness (Hunter whiteness, JIS P8123) was measured. When the whiteness is 70 or more, there is no practical problem. In particular, when the whiteness is 75 or more, it can be evaluated that the whiteness is good enough and satisfactory. Table 1 shows the test results.

[0079]

[Table 1]

[0080]

As is clear from the results shown in Table 1, the present invention clearly shows the distinction between a low-temperature coloring red image and a high-temperature coloring black image, with less background fog and high whiteness. It has become possible to produce a color heat-sensitive recording material.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B41M 5/18 108

Claims (5)

[Claims] 1. A support having a thermosensitive coloring layer formed thereon, wherein the thermosensitive coloring layer comprises: (1) at least one polymer selected from polyurea and polyurethane; (2) solid fine particles of a blue or green color-forming dye precursor, and (2) solid fine particles of a blue or green color-forming dye precursor; The above-mentioned black-based coloring dye precursor, red-based or yellow-based coloring dye precursor, blue-based or green-based coloring dye precursor, and a color-developing compound that causes a color-forming reaction when heated. Multicolor heat-sensitive recording material. 2. A support having a thermosensitive coloring layer formed thereon, wherein said thermosensitive coloring layer comprises: (1) at least one polymer selected from polyurea and polyurethane; (2) at least one kind of polymer substance selected from polyurea and polyurethane, and at least one kind of red or yellow color-forming dye precursor (3) solid fine particles of a blue-based or green-based chromogenic dye precursor, and (4) the black-based chromogenic dye precursor, the red-based or yellow-based chromogenic dye precursor, and blue. A multicolor heat-sensitive recording material, comprising a color-based or green-color-forming dye precursor and a color-developing compound that causes a color-forming reaction when heated. 3. The red or yellow chromogenic dye precursor is 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane,
3-diethylamino-7,8-benzofluoran, 3-
Diethylamino-7-phenoxyfluoran, 3,3-
Bis (1-n-butyl-2-methylindol-3-yl) phthalide, (N-ethyl-N-isoamyl) amino-7-phenoxyfluoran, at least one selected from 3,6-dimethoxyfluoran The multicolor heat-sensitive recording material according to claim 1. 4. The method according to claim 1, wherein at least one of the composite fine particles is
(1) a black-based coloring dye precursor, (2) a red-based or yellow-based coloring dye precursor, at least one dye precursor selected from the group consisting of polyurea and polyurethane by polymerization. The polymer-forming raw material to be dissolved and mixed in a water-insoluble organic solvent having a boiling point of 100 ° C. or less, the organic solvent solution is emulsified and dispersed in an aqueous medium, and the emulsified dispersion is heated to volatilize the organic solvent. 4. The multicolor heat-sensitive recording material according to claim 1, which is prepared by removing and then polymerizing the polymer-forming raw material. 5. The method according to claim 1, wherein at least one of the composite fine particles is at least one of polyurea and polyurethane by polymerization.
A polymer-forming raw material for forming a seed is used as a solvent, and at least one dye precursor selected from (1) a black color-forming dye precursor and (2) a red or yellow color-forming dye precursor is used. 4. A solution prepared by emulsifying and dispersing a solute solution in an aqueous medium and heating the emulsified dispersion to polymerize the polymer-forming raw material.
2. The multicolor heat-sensitive recording material according to item 1.