JPH10315629A - Multicolor thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the contamination of a developed image of desired colors by different colors or minimize the contamination by dispersing a third dye precursor which is of a specific structure to develop a different color from colors developed by a first and a second dye precursor, into a thermally developing layer as a solid microparticle. SOLUTION: A third dye precursor which develops a different color from colors developed by a first and a second dye precursor is dispersed into a thermally developing layer in solid microparticles. This third dye precursor is selected from among fluoran precursor compounds expressed by formula (R<1> , R<2> are mutually independently a hydrogen atom and a 1-6C chain alkyl group; R<3> , R<4> are such that one of them is the hydrogen atom and the other is the 1-6C chain alkyl group; X<1> , X<2> , X<3> and X<3> are mutually independently the hydrogen atom and the 1-4C alkyl group; X<5> is the hydrogen atom and a 1-4C alkyl group; and n is 0 or an integer of 1-4).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-color heat-sensitive recording apparatus capable of recording multi-color images of three or more different colors by applying three or more different heating and coloring conditions from a thermal head. It is about materials. More specifically, in the present invention, the color of an image formed by low applied color energy has almost no color mixture of two or more images formed by higher applied energy, so that a clear multicolored color tone is obtained. The present invention relates to a multicolor heat-sensitive recording material which is obtained and has less background fog.

[0002]

2. Description of the Related Art Conventionally, a color-forming dye precursor and a color-developing agent which makes contact with the color-forming dye precursor under heating to form a color are utilized, and the two color-forming substances are melt-contacted by heating. Thermal recording materials are known which are made to react with each other to obtain a color image. Such a heat-sensitive recording material is relatively inexpensive, has a compact recording device, and is easy to maintain. Therefore, it is widely used as a recording medium for facsimile machines, word processors, various computers, and other applications. Have been.

[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 includes characters to be emphasized and / or
Alternatively, since there is an advantage that a graphic image can be displayed very clearly with a color different from that of another image or a part thereof, demand for its practical use is increasing.

[0004] As a multicolor recording system, attempts have been made to record a multicolor image by utilizing a difference in heating and coloring temperature or a difference in coloring and heating energy, and various multicolor heat-sensitive recording materials have been proposed. . Generally, a multicolor thermal recording material is
On a support, two or more color-forming layers, each of which is colored by a different color-heating temperature or a different color-applied energy in different colors, are sequentially laminated, and these are roughly classified. Then, it is divided into two types, a decoloring type and an adding type.

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 coloring layer develops color by the low-temperature coloring operation, and when heating at high temperature, the coloring system of the low-temperature coloring layer is erased. This is a method in which a decoloring agent having a color effect acts to prevent color development, and only the high-temperature color-forming layer develops color. This method has the advantage of being able to freely select the coloring color,
In order to obtain a sufficient decoloring effect on the low-temperature coloring layer, it is necessary to add a large amount of a decoloring agent. Then, due to the action of the decoloring agent added in a large amount, the recorded color-developed image in the low-temperature color-developing layer fades during long-term storage, or an extra amount of heat is required to melt the decoloring agent. There is a problem that an excessive load is imposed, and it is not always satisfactory in terms of image recording reliability and recording sensitivity.

On the other hand, examples of the color-added multicolor heat-sensitive recording material are disclosed in JP-B-49-27708 and JP-B-51-19.
As disclosed in JP-A-989 and JP-A-51-146239, discrimination can be made by laminating two color-forming layers that develop different colors and applying different amounts of heat (applied energy) to these layers. A method for obtaining two colors is described. In this method, at low temperature, the upper color-forming layer forms a color to form a low-temperature color-forming image, and at high temperature, both upper and lower color-forming layers form a color to obtain a mixed color image of both colors.
Such a multicolor recording material is suitable for the case where the lower color forming layer has a black color developing system. In addition-colored multicolor heat-sensitive recording materials, since no decoloring agent is used, there is an advantage that color-developed recording images have excellent long-term storage properties, and can be manufactured relatively inexpensively. Since no extra heat is required, there is an advantage in that the high-temperature coloring layer can be colored with lower energy than the decoloring type. However, the color-added two-color heat-sensitive recording material has a problem that when the applied energy at the time of low-temperature coloring is excessive, the coloring of the high-temperature coloring layer is partially mixed, so that the low-temperature coloring image is hardly sharpened. Japanese Patent Application Laid-Open No. 56-99697 describes a method in which two or more kinds of color-forming dye precursors having different coloring colors and different average particle diameters are mixed in the same layer. At the time of coloring, there is a problem that color mixing of high-temperature coloring is inevitable.

The application of microcapsules to heat-sensitive recording materials has been known for a long time.
Japanese Patent Application Laid-Open No. 9-70 describes that a substance that is in a liquid state at room temperature is accommodated in a core of a capsule. Examples of microcapsules containing a coloring component-based dye precursor as a core material,
JP-A-57-12695 and JP-A-59-21
4691, and the like. Furthermore, fairness 4
JP-A-4960 and JP-A-4-101885 disclose that each of color-forming components that form colors different from each other is dissolved in a solvent, and each of the solutions is applied to two or more types of microcapsules having different glass transition temperatures. It is described that a multicolor image can be recorded by using these microcapsules having different colors. However, when two or more kinds of chromogenic dye precursors that form different colors are separately microencapsulated, the sensitivity of each of these chromogenic dye precursors decreases, which makes it difficult to classify the sensitivities. There is a problem that color mixing is likely to occur, and in particular, it is extremely difficult in practice to classify the sensitivity of three or more color-forming dye precursors. Further, when the oil-based liquid solution of the color-forming dye precursor is encapsulated in the microcapsules, the capsules are broken by pressure or friction, so that there is a problem that the ground color is likely to occur.

Further, an attempt to record a multicolor image by combining heat and light utilizing the property that a diazo compound is decomposed by light has been made in JP-A-60-242093 and JP-A-6-242093.
No. 1-40192 and the like. However, the color recording image obtained by this method has excellent preservability, but has a drawback that the apparatus becomes large and as a result, high compactness as an advantage of the thermal recording method is lost.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a multicolor heat-sensitive recording material capable of forming three or more different color images by different color application energies.
At each of the different color application energy levels, the desired color image has no or little color mixture different from that, and no or little background fog (ground color), and high whiteness multicolor thermal recording. It is intended to provide materials.

[0010]

SUMMARY OF THE INVENTION A multicolor heat-sensitive recording material (1) according to the present invention comprises a support, and a substantially colorless, formed on the support and substantially colorless. A multicolor thermosensitive coloring layer containing a plurality of dye precursors that develop different colors, a developer that reacts with these dye precursors under heating to develop the color, and a binder, In the color-forming layer, (1) a first dye precursor that forms color at low applied energy is dispersed in the heat-sensitive color-forming layer in the form of solid fine particles;
(2) a second color developing different color from the first dye precursor;
A dye precursor, a solvent component containing a polyvalent isocyanate-containing polymerizable raw material, including the second dye precursor, an oil solution comprising a solute component dissolved in the solvent component,
Emulsified and dispersed in an aqueous medium, obtained by subjecting the polymerizable material in the emulsified and dispersed particles to a polymerization reaction and polymerizing the same, and contained in the composite fine particles dispersed in the thermosensitive coloring layer. The second dye precursor contained in the composite fine particles develops a color with a higher applied energy than the first dye precursor fine particles, and (3) is higher than the second dye precursor. A third dye precursor that develops a color different from the first and second dye precursors due to the applied energy is dispersed in the thermosensitive coloring layer in the form of solid fine particles, and the third dye precursor is Has the following general formula (I):

Embedded image(However, in the above formula (I), R¹And R^TwoAre
Independently, a hydrogen atom, C₁~ C₆Chain alkyl group, C
_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C ₇~ C
₂₀Aralkyl groups, substituted and unsubstituted phenyl groups,
To C_Two~ C_TenMember selected from the alkoxyalkyl groups of
Wherein R¹And R^TwoAre they combined
Pyrrolidino, piperidino,
And a member selected from morpholino groups
Well, R^ThreeAnd R^FourMeans that one of them is water
Represents a hydrogen atom, the other being a hydrogen atom, C₁~ C₆Chain alk
Group, C_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C
₇~ C₂₀Aralkyl groups, substituted and unsubstituted phenyl groups,
And C_Two~ C_TenOne selected from alkoxyalkyl groups
X¹, X^Two, X^ThreeAnd X^FourAre
Independently, a hydrogen atom, C₁~ C_FourAlkyl group, C₁~
C₈Alkoxyl group, halogen atom, methyl halide
Groups, nitro groups, and substituted and unsubstituted amino groups
And X¹~ X^FourTwo adjacent to each other
And the two carbon atoms of the benzene ring structure to which they are attached
May form a substituted or unsubstituted aromatic cyclic structure
, X^FiveIs a hydrogen atom, C₁~ C₆Alkyl group, C₁~ C
₈Alkoxyl groups, substituted and unsubstituted amino groups, and
Represents a member selected from a halogen atom, and n is 0 or 1 to
4 represents an integer of 4₇~ C₂₀Aralkyl groups,
And each of the substituted phenyl groups independently of the other₁
~ C_FourAlkyl group, C₁~ C₈Alkoxyl groups and positions
At least one position selected from substituted or unsubstituted amino groups
Having a substituent, each of the substituted amino groups
Is C₁~ C₈At least one selected from alkyl groups
Having a substituent of Fluo represented by)
Characterized by being selected from the precursor compounds of the orchids
is there. In the multicolor heat-sensitive recording material (1) of the present invention,
The heat-sensitive coloring layer is different from the first to third dye precursors.
A fourth dye precursor that forms a color, wherein the fourth dye
Precursor containing a polyvalent isocyanate-containing polymerization raw material.
A medium component and the fourth dye precursor, wherein the solvent component
An oily solution consisting of a solute component dissolved in
Emulsified and dispersed in a medium;
Is obtained by subjecting the raw material to a polymerization reaction and polymerizing this.
In the composite fine particles dispersed in the thermosensitive coloring layer.
Contained in the composite fine particles
The fourth dye precursor, the first dye precursor fine particles of the
Higher than the coloring application energy, the third dye precursor fine
Lower than the applied color energy of the fine particles, and the composite
Energy for color development of the second dye precursor contained in the fine particles
It develops color with applied energy different from lugi.
There may be. Also, the multicolor heat-sensitive recording material of the present invention.
(1) In the thermosensitive coloring layer, the first to third dyes
A fourth dye precursor that develops a different color from the precursor is further included.
The fourth dye precursor is dispersed in the thermosensitive coloring layer.
Contained in the core of the microcapsules
The fourth dye precursor contained in this microcapsule
Is the color-forming applied energy of the first dye precursor fine particles.
Higher than that of the third dye precursor fine particles.
Energy, and contained in the composite fine particles.
Mark different from the applied color developing energy of the second dye precursor
It may be one that develops color by an applied energy. Departure
Another multicolor heat-sensitive recording material (2) according to the present invention comprises a support,
Formed on the support and substantially colorless
Different colors due to different applied energies
A plurality of dye precursors that develop color, and these dye precursors
A developer and a binder that react under heating to develop color
And a multicolor heat-sensitive coloring layer containing:
In the middle, (1) the color developing by low applied energy
1 the dye precursor is dispersed in the form of solid fine particles,
(2) a second color developing different color from the first dye precursor;
A dye precursor is dispersed in the thermosensitive coloring layer.
Microcapsules contained in the core of
The second dye precursor in the capsule emits the first dye precursor.
Color is developed with applied energy higher than color applied energy
And (3) a higher applied energy than the second dye precursor.
Different from the first and second dye precursors depending on the energy
The third dye precursor that develops a color is formed into solid fine particles.
The third dye precursor dispersed in the thermosensitive coloring layer,
The body has the following general formula (I):

Embedded image(However, in the above formula (I), R¹And R^TwoAre
Independently, a hydrogen atom, C₁~ C₆Chain alkyl group, C
_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C₇~ C₂₀
Aralkyl groups, substituted and unsubstituted phenyl groups, and C
_Two~ C_TenLists members selected from alkoxyalkyl groups
Provided that R¹And R^TwoAre they combined
Along with the nitrogen atom, pyrrolidino, piperidino and
And morpholino groups.
K, R^ThreeAnd R^FourMeans that one of them is a hydrogen source
And the other is a hydrogen atom, C₁~ C₆Chain alkyl
Group, C_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C₇
~ C₂₀Aralkyl groups, substituted and unsubstituted phenyl groups,
C_Two~ C_TenMember selected from alkoxyalkyl group
And X¹, X^Two, X^ThreeAnd X^FourAre each other
Independently of the hydrogen atom, C₁~ C_FourAlkyl group, C₁~ C
₈Alkoxyl group, halogen atom, methyl halide
Groups, nitro groups, and substituted and unsubstituted amino groups
And X¹~ X^FourTwo adjacent to each other
Together with the carbon atom of the benzene ring structure to which they are attached.
Or a substituted or unsubstituted aromatic cyclic structure;
^FiveIs a hydrogen atom, C ₁~ C₆Alkyl group, C₁~ C₈Al
Coxyl groups, substituted and unsubstituted amino groups, and halogenated
N represents a member selected from the group consisting of
The substitution C₇~ C₂₀Aralkyl groups and substitutions
Each of the phenyl groups is independently of the other₁~ C_FourA
Alkyl group, C₁~ C₈Alkoxyl group and substitution and
At least one substituent selected from unsubstituted amino groups
Wherein each of the substituted amino groups is C
₁~ C₈Has one or more substituents selected from alkyl groups
Is what you do. ) Represented by the fluoran precursor
It is characterized by being selected from compounds. Said many
In the color thermosensitive recording material (2), the thermosensitive coloring layer is
The fourth dye which develops a color different from the first to third dye precursors
A precursor, wherein the fourth dye precursor comprises the heat-sensitive dye.
Included in the core of microcapsules dispersed in the coloring layer
Has been contained in the microcapsules
The fourth dye precursor is a colorant of the first dye precursor fine particles.
Higher than the applied energy, the third dye precursor fine particles
Lower than the applied color energy of the
Coloring applied energy of the second dye precursor contained in the capsule
Color with an applied energy different from the
You may.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The multicolor heat-sensitive recording material of the present invention (1)
And (2) a heat-sensitive color-forming layer, a support, and a plurality of dye precursors formed on the support, which are substantially colorless, and which are colored in different colors by different applied energies; And a multicolor thermosensitive coloring layer containing a binder which reacts with the dye precursor of the formula (1) under heating to develop the color and a binder.

In the heat-sensitive color-forming layer of the multicolor heat-sensitive recording material (1) of the present invention, (1) the first dye precursor which forms a color at a low applied energy is pulverized into solid fine particles; Are distributed. (2) The second dye precursor develops a color different from that of the first dye precursor, and is contained in the composite fine particles. Including a solvent component, and the second dye precursor,
An oily solution comprising a solute component dissolved in the solvent component is emulsified and dispersed in an aqueous medium, and the polymerizable raw material in the emulsified and dispersed particles is subjected to a polymerization reaction to be obtained by polymerization. And dispersed in the thermosensitive coloring layer. As described above, the second dye precursor contained in the composite fine particles develops a color with an applied energy higher than that of the first dye precursor fine particles. (3) The third dye precursor develops a color different from that of the first and second dye precursors due to a higher applied energy than the second dye precursor, and has been pulverized into solid fine particles. Are dispersed in the thermosensitive coloring layer. The third dye precursor is selected from the specific fluoran precursor compounds represented by the general formula (I).

In the heat-sensitive color-forming layer of the multicolor heat-sensitive recording material (2) of the present invention, (1) the first dye precursor which forms a color by low applied energy is pulverized into solid fine particles; Are distributed. (2) The second dye precursor is colored in a different color from the first dye precursor, is contained in the core of the microcapsules dispersed in the thermosensitive coloring layer, and The second dye precursor in the capsule develops a color with an applied energy higher than the applied color energy of the first dye precursor. (3) The third dye precursor develops a color different from the first and second dye precursors by an applied energy higher than that of the second dye precursor, and is crushed into solid fine particles. And is dispersed in the thermosensitive coloring layer. The third dye precursor is selected from the specific fluoran precursor compounds represented by the general formula (I).

In the multicolor heat-sensitive recording materials (1) and (2) of the present invention, the first dye precursor which has been pulverized into solid fine particles develops a color at the lowest color-forming temperature (low color-forming applied energy). At a high coloration temperature (high coloration application energy), the third
The dye precursor, that is, the specific fluoran precursor compound represented by the general formula (I) develops a color, and at a temperature intermediate between the low temperature and the high temperature (medium temperature) (medium coloring applied energy), in the composite fine particles, or The second dye precursor contained in the core of the microcapsule develops a color. The colors that develop at the low, medium, and high temperatures (low, medium, and high color application energies) are different from each other.

In the multicolor heat-sensitive recording materials (1) and (2) of the present invention, (1) the first dye precursor in the form of fine solid particles is mixed with a developer by melting by heating from a thermal head. Color develops on contact. Since the color development start temperature is the eutectic point of the first dye precursor, the color developer, and the sensitizer and the like which will be described later, if necessary, it is lower than the melting point of the first dye precursor alone. Usually, depending on the selection of the sensitizer and the like, the eutectic point of the first dye precursor, the developer, and the sensitizer added as needed, that is, the color development start temperature of the first dye precursor is 70 ° C.
To 100 ° C. (2) On the other hand, the formula (II) used as a third dye precursor
When heated, the fluoran precursor compound forms a fluoran compound (third dye precursor) by a dehydration reaction when heated, and then reacts with the color developer to form a dye and develops a two-stage reaction. Since the color develops through the third dye precursor, the color development of the third dye precursor requires a considerably larger amount of applied energy for color development than the first dye precursor, and thus the color development onset temperature is significantly higher than that of the first dye precursor. Become. (3) Further, since the second dye precursor is contained in the composite fine particles or microcapsules, the second dye precursor comes into melt contact with a developer and a sensitizer added as necessary. In order to react and develop color, the composite fine particles or microcapsules must be melted.
By adjusting the energy required for this melting to an appropriate level, the color development application energy (color development temperature) required for coloring the second dye precursor-containing composite fine particles or microcapsules can be reduced. It can be adjusted to be higher than the coloring application energy (coloring temperature) required for coloring the particles, but lower than the coloring application energy (coloring temperature) required for coloring the third dye precursor fine particles. In the case of the composite fine particles, the adjustment of the color application energy (color developing temperature) of the second dye precursor-containing composite fine particles or microcapsules is mainly controlled by the particle size, the type of the polymer, and the composition. Selection of the type, blending ratio and amount of the polyvalent isocyanate compound and, if necessary, the polyol and / or polyvalent amine;
By selectively adjusting the mixing ratio of the dye precursor and the polymerizable material, and in the case of microcapsules, the particle size, the type of wall membrane material, the composition, the thickness of the film, and the content of the second dye precursor It can be achieved by selectively adjusting the amount, the type and amount of the solvent of the core liquid, and the like.

The full dye of the formula (I) constituting the third dye precursor
In the orane precursor compound, R¹And R^TwoIs it
Each independently a hydrogen atom, C₁~ C₆Chain alkyl
Groups such as methyl, ethyl, n- and iso-propyl,
n-, iso- and sec-butyl, heptyl and
Cyl groups such as xyl groups_Three~ C₆Cyclic alkyl groups such as
Clopropyl, cyclopentyl and cyclohexyl
Group, substituted and unsubstituted C ₇~ C₂₀Aralkyl groups, for example
Substituted and unsubstituted benzyl, phenethyl, and phenyl
Substituted and unsubstituted phenyl groups, such as propyl, and
C_Two~ C_TenAn alkoxyalkyl group such as methoxymethyl
, Ethoxymethyl, methoxypropyl and ethoxy
A member selected from the group consisting of propyl group,¹
And R^TwoTogether with the nitrogen atom to which they are attached
A pyrrolidino group, a piperidino group, and a morpholino
It may form a member selected from the groups. R^Threeand
R^FourMeans that one of them represents a hydrogen atom and the other
Is a hydrogen atom, C₁~ C₆A chain alkyl group (eg, methyl
, Ethyl, propyl, butyl, heptyl and hexyl
Group), C_Three~ C₆Cyclic alkyl groups (eg, cyclo
Propyl, cyclopentyl and cyclohexyl groups
Etc.), substituted and unsubstituted C₇~ C₂₀Aralkyl groups (for example,
Substituted and unsubstituted benzyl, phenethyl, and phenyl
Propyl group), substituted and unsubstituted phenyl groups,
C_Two~ C_TenAlkoxyalkyl groups (eg methoxy
Methyl, ethoxymethyl, methoxypropyl and ethoxy
Xypropyl group). X¹, X
^Two, X^ThreeAnd X^FourAre independently of each other
Child, C₁~ C_FourAlkyl groups (eg, methyl, ethyl,
Propyl and butyl groups), C₁~ C₈Alkoxyl
Groups such as methoxy, ethoxy, butoxy, and hex
A siloxy group, etc.), a halogen atom (for example, chlorine,
, Bromine, etc.), methyl halide groups (for example, methyl chloride
Nitro group, and substitution and
Represents an unsubstituted amino group, provided that X¹~ X^FourNext to each other
Two of the mating are the benzene ring structure to which they are attached
A substituted or unsubstituted aromatic ring structure with two carbon atoms
(For example, substituted or unsubstituted benzene ring, naphthalene ring,
And anthracene ring). X^Five
Is a hydrogen atom, C₁~ C₆Alkyl groups (eg, methyl, d
Tyl, propyl, butyl, hexyl, etc.), C₁~ C
₈Alkoxyl groups (eg methoxy, ethoxy, butoxy)
And hexyloxy groups), substituted and unsubstituted
Amino groups, and halogen atoms (eg, chlorine, fluorine, odor
Element). n is 0 or 1-4
Represents an integer. The R¹, R^TwoOr R^ThreeAnd R^FourOne of
The substitution C represented by₇~ C₂₀Aralkyl groups and
R¹, R^TwoOr R^ThreeAnd R^FourPermutation represented by one of
Each of the phenyl groups is independently of the other₁~ C_FourA
Alkyl group, C₁~ C₈Alkoxyl groups and substituted or unsubstituted
Having at least one substituent selected from substituted amino groups
X¹~ X^FiveA substitution represented by
A mino group, and the substituted C₇~ C₂₀Aralkyl groups and aralkyl groups
Substituted phenyl group, substituted amino group included as a substituent
Each is C₁~ C₈Less selected from alkyl groups
Both have one substituent.

In one embodiment of the multicolor heat-sensitive recording material (1) of the present invention, the heat-sensitive coloring layer further contains a fourth dye precursor which develops a color different from the first to third dye precursors. In this case, the fourth dye precursor is contained in the composite fine particles dispersed in the thermosensitive coloring layer, and the composite fine particles are mixed with a solvent component containing a polyvalent isocyanate-containing polymerization raw material and the fourth dye precursor. An oil solution comprising a dye precursor and a solute component dissolved in the solvent component,
It is obtained by emulsifying and dispersing in an aqueous medium and subjecting the polymerization raw material in the emulsified and dispersed particles to a polymerization reaction to polymerize the same. The fourth dye precursor contained in the composite fine particles is higher than the coloring application energy of the first dye precursor fine particles, and lower than the coloring application energy of the third dye precursor fine particles, In addition, the color is developed by an applied energy different from the applied energy of the second dye precursor contained in the composite fine particles.

In another embodiment of the multicolor thermosensitive recording material (1) of the present invention, the thermosensitive coloring layer further comprises a fourth dye precursor which develops a color different from the first to third dye precursors. Wherein the fourth dye precursor is contained in the core of microcapsules dispersed in the thermosensitive coloring layer. The fourth dye precursor contained in this microcapsule is higher than the color application energy of the first dye precursor fine particles, lower than the color application energy of the third dye precursor fine particles, and The color is formed by an applied energy different from the applied color energy of the second dye precursor contained in the composite fine particles.

In one embodiment of the multicolor heat-sensitive recording material (2) of the present invention, the heat-sensitive coloring layer further includes a fourth dye precursor which develops a color different from the first to third dye precursors, The fourth dye precursor is contained in the core of the microcapsules dispersed in the thermosensitive coloring layer. The fourth dye precursor contained in the microcapsules is higher than the coloring applied energy of the first dye precursor fine particles, lower than the coloring applied energy of the third dye precursor fine particles, and The color is formed by an applied energy different from the applied color energy of the second dye precursor contained in the capsule.

In one embodiment of the multicolor heat-sensitive recording material (1) or (2) of the present invention, the heat-sensitive coloring layer is formed of the first to third thermosensitive recording layers.
Different from the dye precursor, and further comprising two or more additional dye precursors that each develop a different color, each of the two or more additional dye precursors, independently of each other, It is contained in the composite fine particles or in the core of the microcapsule. The composite fine particles, a solvent component containing a polyvalent isocyanate-containing polymerizable raw material, including the one kind of the additional dye precursor, an oily solution comprising a solute component dissolved in the solvent component, an aqueous solution It is obtained by emulsifying and dispersing in a medium, subjecting the polymerizable material in the emulsified and dispersed particles to a polymerization reaction to polymerize the same, and being dispersed in the thermosensitive coloring layer. In addition, each of the two or more additional dye precursors develops a color with a different applied energy, and is higher than the coloring applied energy of the first dye precursor fine particles, and the third dye precursor fine particles And the color is applied by an applied energy different from the applied energy of the second dye precursor contained in the composite fine particles or microcapsules.

The composite fine particles used in the present invention are:
A solvent component containing a polyvalent isocyanate compound-containing polymerizable raw material, and a desired dye precursor, containing an oily solution comprising a solute component dissolved in the solvent component in an aqueous medium, for example, an aqueous solution containing a hydrophilic protective colloid. It is prepared by emulsifying and dispersing, raising the temperature of the emulsified dispersion system as necessary, and subjecting a polymerizable raw material, for example, a polyvalent isocyanate compound in the emulsified and dispersed particles to a polymerization reaction to polymerize the same. The composite fine particles contain the dye precursor in a molecular state (solid solution state), and since the composite fine particles substantially do not contain an organic solvent, their physical strength is high.
For this reason, the composite fine particles in the multicolor heat-sensitive recording material of the present invention are excellent in pressure resistance and friction resistance. In addition, the dye precursors contained in each of the composite fine particles each exhibit high sequestration properties with respect to others, and have less coloration of background fog due to heat and humidity. The dye precursor-containing composite fine particles used in the present invention are a polyurea formed by a polymerization reaction of a polyvalent isocyanate-containing polymerizable material, and at least one polymer selected from polyurethane and a polymerizable dye-containing solvent. A solute containing a dissolved chromogenic dye precursor, the dye precursor-containing solute is mixed at a molecular level in a matrix made of a polymer formed by polymerization of a polymerizable raw material, and a solid solution state is formed. It is thought that it does. The appearance of the composite fine particles is almost spherical when observed with an electron microscope, or is a red blood cell with a hollow in the middle.

The dye precursor contained in the composite fine particles used in the multicolor heat-sensitive recording material of the present invention is mixed at the molecular level in the polymer matrix as described above. Compared to solid fine particles consisting of a body alone, there is almost no direct contact with developer particles or sensitizer particles added as needed in the thermosensitive coloring layer. For this reason, the coloring start temperature or the energy required for color development of the dye precursor contained in the composite fine particles is required for the color formation start temperature or color development of the first dye precursor in the form of solid fine particles sensitized by a decrease in melting point. Higher than the applied energy. It is thought that the reason why the coloring sensitivity of the first dye precursor fine particles and the dye precursor-containing fine particles can be clearly distinguished is that the above-described coloring start temperature or the coloring application energy is clearly different. Can be

In the production of the composite fine particles used in the present invention, first, a solute containing a required dye precursor is dissolved in a solvent containing a polymerizable raw material containing a polyvalent isocyanate compound to prepare a solution. The dissolution temperature at this time is preferably 70 ° C. or higher, and at a temperature lower than 70 ° C., the solubility of the solute dye precursor in the solvent containing the polyvalent isocyanate compound is low, and the composite fine particles having sufficient separability are obtained. Sometimes particles cannot be produced. This solution is added to an aqueous medium,
For example, emulsified and dispersed in an aqueous medium containing a protective colloid substance such as polyvinyl alcohol dissolved therein, and if necessary, a reactive substance such as a water-soluble polyamine is added thereto,
The emulsified dispersion is heated to a temperature of 40 ° C. or higher as required, and the polymerizable raw material in the emulsified dispersed particles is polymerized. The polymer matrix comprising polyurea or polyurethane-polyurea is contained in the matrix in a solid solution state. To form composite fine particles comprising the dye precursor.

In the multicolor heat-sensitive recording material (2) of the present invention, microcapsules containing the second dye precursor are used in the heat-sensitive coloring layer instead of the fine particles containing the second dye precursor as described above. Conventionally, as a method known as a microencapsulation method, there are a coacervation method, an interfacial polymerization method, an in situ method, and the like. In particular, the microencapsulation method by the interfacial polymerization method is useful in various fields since microencapsulation with various characteristics is possible. The microcapsules used in the multicolor thermosensitive recording material (2) of the present invention include a microcapsule wall film made of a thermoplastic resin and a dye precursor contained in the core. Polyurethane, polyurea, polyester,
Examples thereof include polyamide, polystyrene, and polycarbonate. A solution obtained by dissolving a solute composed of a polyvalent isocyanate compound and a dye precursor in a solvent composed of a hydrophobic substance is emulsified and dispersed in an aqueous medium, preferably a hydrophilic protective colloid solution, and the emulsified dispersion is raised. Upon heating, a wall film made of polyurethane-polyurea or polyurea is formed, and a dye precursor-containing solution is contained in a core surrounded by the wall film. It is easy to produce various microcapsules having different thermal characteristics such as the glass transition temperature of the microcapsule wall film. As the hydrophobic substance used in the production of microcapsules, a substance capable of dissolving a dye precursor is used, for example, paraffin oil,
Cottonseed oil, soybean oil, corn oil, olive oil, castor oil, fish oil, lard oil, chlorinated paraffin, chlorinated diphenyl, dibutyl phthalate, dioctyl phthalate, tributyl phthalate, tricresyl phosphate, dibutyl malate, o-dichlorobenzene, diisopropyl naphthalene And alkylated naphthalene, 1-phenyltrixylylethane, 1- (3,4-dimethylphenyl) -1-phenylethane and the like.

The second color-forming dye in the microcapsule used in the multicolor heat-sensitive recording material (2) of the present invention is isolated from the outside of the capsule by a polymer wall film, which melts the wall film and Since energy for coloring the dye precursor therein is required, compared with solid fine particles of the dye precursor alone, in the thermosensitive coloring layer, direct contact with the developer fine particles or the sensitizer fine particles occurs. Little physical contact. For this reason, the color development start temperature or the applied energy required for color development of the dye precursor-containing microcapsules is calculated from the color development start temperature or the applied energy required for color development of the first dye precursor in the solid fine particle state sensitized by the melting point drop. Can also be higher. The reason why the coloring sensitivity of the first dye precursor fine particles and the dye precursor-containing composite fine particles can be clearly distinguished is considered to be due to the difference in the coloring start temperature or the coloring start applied energy as described above. Can be

In the production of the dye precursor-containing microcapsules used in the present invention, for example, one example of the above-mentioned method for producing the dye precursor-containing microcapsules having a wall film made of polyurethane-polyurea or polyurea resin is as follows. , A dye precursor, and a polymerizable material such as a polyvalent isocyanate compound are dissolved in the hydrophobic liquid to prepare a solution. This solution is emulsified and dispersed in an aqueous medium, preferably an aqueous medium in which a protective colloid substance such as polyvinyl alcohol is dissolved, and if necessary, a polymerizable substance such as a water-soluble polyamine is added thereto. Is heated to a temperature of 40 ° C. or higher, and the polymerizable raw material is an aqueous medium,
Polymerized at the interface with the emulsified dispersed particles, thereby forming a polyurea or polyurethane-polyurea resin as a wall film,
It is surrounded by it to form microcapsules containing the dye precursor / hydrophobic liquid solution as core liquid.

The dye precursor used in the present invention includes:
Leuco compounds such as triaryl, diphenylmethane, thiazine, spiropyran, lactam, and fluoran dyes can be preferably used. In the multicolor heat-sensitive recording material of the present invention, since the second dye precursor contained in the composite fine particles or the microcapsules is used, the color obtained from the first dye precursor in the form of solid fine particles is the second dye precursor. It is preferable that the color can be clearly distinguished from the color obtained from the dye precursor. In addition, if the color obtained from the first dye precursor or the second dye precursor is a low-brightness color such as black, it should be clearly distinguished from the color obtained from the third dye precursor. However, it is not preferable to use a material that develops such a low lightness color as the first and / or second dye precursor.

In the present invention, those used as dye precursors other than the third dye precursor (the fluoran precursor compound of the formula (I)) include the following compounds. Dye precursors that develop colors of red, magenta and orange colors include 3,6-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-7-chlorofluoran, 3-diethylamino-
7-bromofluorane, 3-diethylamino-7,8-
Benzofluoran, 3-diethylamino-6,8-dimethylfluoran, 3-diethylamino-6-methyl-7
-Chlorofluoran, 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, 3- (N-ethyl-N-isoamylamino) -7,8-benzofluoran and the like can be mentioned.

Dye precursors that develop colors of red, magenta and orange colors further include 3-cyclohexylamino-6-chlorofluoran and 3-di-n-butylamino-6-methyl-7-bromo. Fluoran, 3-di-n-
Butylamino-7,8-benzofluoran, 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-carboboxyanilino) -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-butylamino Fluorane, and 2- (N-methylanilino) -3-methyl-6-di-n-butylaminofluoran.

As a dye precursor which develops red, magenta and orange colors, 3,3'-bis (1-n-butyl-2-methylindol-3-yl)
Phthalide, 3,3'-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3'-bis (1-
n-octyl-2-methylindol-3-yl) phthalide, 7- (N-ethyl-N-isoamylamino) -3
-Methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide], 7- (N-ethyl-N-isoamylamino) -3
-Methyl-1-p-methylphenylspiro [(1,4-
Dihydrochromeno [2,3-c] pyrazole) -4,
3'-phthalide], and 7- (N-ethyl-Nn-
Hexylamino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide] and the like can be used.

As the dye precursor which emits blue light,
3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl)
-6-dimethylaminophthalide, 3- (1-ethyl-2
-Methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-
Diethylaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-diethylaminophenyl) -4
-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-hexyloxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-diphenylamino-6-diphenylaminofluoran, and the like.

The dye precursor that emits green color includes 3-
(N-ethyl-Nn-hexylamino) -7-anilinofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3,3-bis (4-diethylamino-
2-ethoxyphenyl) -4-azaphthalide, 3- (N
-Ethyl-Np-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 can be mentioned.

3,6-dimethoxyfluorane and 1- (4-
n-dodecyloxy-3-methoxyphenyl) -2-
(2-quinolyl) ethylene and the like. The above dye precursor may be used alone, but it is also effective to use the dye precursor together with a dye precursor that develops another color for color tone correction.
Further, as the dye precursor to be contained in the composite fine particles, an oxidation type dye precursor can be used in addition to the above-described electron donating dye precursor. Alternatively, a color-forming diazonium salt may be contained in the composite fine particles, and may be reacted with a coupler contained as a color developer in the thermosensitive coloring layer to form a color.

In the present invention, when the dye precursor is used as the first dye precursor in the form of solid fine particles, in order to make the dye precursor into fine particles, water is used as a dispersion medium, and a sand grinder, an attritor or the like is used. , Ball mill,
Pulverized by various types of wet pulverizers such as Kobo mill, and the resulting fine particles are modified polyvinyl alcohol such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, and sulfonated polyvinyl alcohol, methylcellulose, carboxymethylcellulose, and styrene-maleic anhydride copolymer salt. And a water-soluble synthetic polymer compound such as a derivative thereof, and a surfactant, if necessary,
It can be dispersed in water together with an antifoaming agent or the like to form a dispersion, and this dispersion can be used for preparing a coating material for forming a thermosensitive coloring layer. After dissolving the dye precursor in a solvent, the solution is emulsified and dispersed in water using the water-soluble polymer compound as a stabilizer, and the solvent is evaporated from the emulsion to recover the dye precursor as solid fine particles. You can also. In each case, the average particle diameter of the first dye precursor particles used in the state of solid fine particles is 0.2 to 0.2 to obtain appropriate color sensitivity.
It is preferably 3.0 μm, more preferably 0.3 μm.
3 to 1.0 μm.

In the present invention, the polyvalent isocyanate compound used for producing the composite fine particles and the microcapsules is a polyurea or a polyurea by reacting with water.
Polyurethane-a compound forming a polyurea, a polyvalent isocyanate compound alone may be used, or a mixture of a polyvalent isocyanate compound and a polyol reacting therewith, or an adduct of a polyvalent isocyanate compound and a polyol, a biuret compound Or a multimer such as isocyanurate. A dye precursor is dissolved in these polyvalent isocyanate compounds, and this solution is emulsified and dispersed in an aqueous medium, preferably an aqueous medium containing and dissolving a protective colloid substance such as polyvinyl alcohol, and further, if necessary, reacting a polyamine or the like. By mixing the emulsified substances and heating the emulsified dispersion, the polymerizable raw materials in the emulsified dispersed particles are polymerized to form a polymer matrix, whereby the dye precursor is molecularly dispersed in the polymer matrix. The composite fine particles contained therein can be formed. Further, these polyvalent isocyanate compound and dye precursor are dissolved in the above-mentioned hydrophobic liquid, and this solution is emulsified and dispersed in an aqueous medium, preferably an aqueous medium containing a protective colloid substance such as polyvinyl alcohol. And
If necessary, a reactive substance such as a polyamine is mixed with the mixture, and the emulsified dispersion is heated to polymerize the polymerizable raw material in the emulsified dispersion particles to form a wall film. A microcapsule containing a core liquid composed of an ionic liquid solution can be formed.

The polyvalent isocyanate compound used as a polymerizable raw material of the composite fine particles or a raw material for forming a wall film of the microcapsules includes, for example, m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4 -Tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 5-isocyanato-1- (isocyanatomethyl) -1,3,3-
Trimethylcyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, tetramethylxylylene diisocyanate, 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,
Diisocyanates such as cyclohexylene-1,2-diisocyanate and cyclohexylene-1,4-diisocyanate; triisocyanates such as 4,4 ', 4 "-triphenylmethane triisocyanate and toluene-2,4,6-triisocyanate And tetraisocyanates such as 4,4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate, etc. Examples of the adduct of a polyvalent isocyanate compound and a polyol include hexamethylene diisocyanate. Isocyanate prep such as trimethylolpropane adduct, 2,4-tolylenediisocyanate trimethylolpropane adduct, xylylenediisocyanate trimethylolpropane adduct, tolylenediisocyanate hexanetriol adduct, etc. Can be used mer. The polyvalent isocyanate compound, for example, biuret of hexamethylene diisocyanate, also multimers such as isocyanurate can be used as a polymer-forming material of the present invention.

Examples of the polyol compound used as the polymerizable raw material of the composite fine particles or the raw material for forming the wall film of the microcapsule include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentane. Diol, 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, pentaerythritol,
Aliphatic polyols such as glycerin, condensation products of aromatic polyhydric alcohols such as 1,4-di (2-hydroxyethoxy) benzene and 1,3-di (2-hydroxyethoxy) benzene with alkylene oxides, p- 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'-dihydroxydiphenylsulfide, ethylene oxide adduct of 4,4'-isopropylidenediphenol, 4,4'-isopropylidenediphenol And acrylates having a hydroxy group in a molecule such as 2-hydroxyacrylate.

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.
These may be used alone, or two or more of these may be used in combination as needed.

Examples of the polymerizable raw material of the composite fine particles used in the present invention or the polyamine compound used as the raw material for forming the wall film of the microcapsules include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine. Diamine, p-phenylenediamine, m-phenylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetriamine,
Examples include triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, and amine adducts of epoxy compounds. Further, other polymer substances can be used in combination as long as the object of the present invention is not impaired.

In order to obtain good color sensitivity, the weight ratio of the dye precursor to the polyvalent isocyanate is 5 to 80% in order to obtain good color sensitivity. %, More preferably 20 to 50% by weight.
In the production of the composite fine particles, the total weight of the polyvalent isocyanate compound and the dye precursor is preferably 90% by weight or more based on the total weight of the oily solution,
This makes it possible to obtain a multicolor heat-sensitive recording material with less white paper fogging.

The weight ratio of the dye precursor to the polyvalent isocyanate compound in the production of microcapsules is such that the weight of the dye precursor is 5 to 50% by weight based on the total weight of the microcapsules in order to obtain good color sensitivity. Is preferably, more preferably 20 to 40% by weight,
The weight of the polyvalent isocyanate is preferably 5 to 50% by weight, more preferably 20 to 40% by weight.

In the present invention, in addition to the dye precursor, the melting point is 40 ° C. or more and 150 ° C. or less and the boiling point is 15
An organic compound having a temperature of 0 ° C. or higher can be used in combination as a sensitizer. As such a sensitizer organic compound, an aromatic ketone compound, an aromatic ether compound, an aromatic cyclic ester compound and the like can be preferably used.
Benzophenone is used as an aromatic ketone compound for a sensitizer, and 1,2-di (m-
Tolyloxy) ethane, 1,2-diphenoxyethane,
And 1- (4-methoxyphenoxy) -2- (2-methylphenoxy) ethane, and the like, and aromatic cyclic ester compounds for sensitizers include coumarin and phthalide. The above-mentioned sensitizer organic compounds may be used alone or in combination of two or more.

In the present invention, the emulsifier (protective colloid agent) used for preparing the composite fine particles or microcapsules includes the water-soluble polymer compound used when dispersing the dye precursor in the form of solid fine particles described above. The same can be used. At the same time, a surfactant, an antifoaming agent and the like may be used in combination. The amount of the emulsifier used in the preparation of the composite fine particles and the microcapsules is not particularly limited, but is generally 1 to 50% by weight based on the total weight of the polymerizable raw materials for forming the composite fine particles or the microcapsules. It is more preferably about 3 to 30% by weight.

In the composite fine particles and microcapsules used in the present invention, an ultraviolet absorber, an antioxidant, an oil-soluble fluorescent dye, a release agent, etc. are added as required in addition to the dye precursor. May be. Such an additive substance is preferably solid at room temperature, but may be liquid. The dye precursor may be composed of a single compound, or may be a mixture of two or more compounds.

In the thermosensitive coloring layer of the present invention, in the composite fine particles,
Alternatively, it is preferable to include an ultraviolet absorber in the microcapsules from the viewpoint of improving the light fastness of a color image,
Benzotriazole-based ultraviolet absorbers such as-(2-hydroxy-5-methylphenyl) -2H-benzotriazole have not only an effect of improving the light resistance of a color image but also an effect of adjusting the color sensitivity, and are preferably used. In addition, a tin compound, a polyamide compound, an epoxy compound, a polyamine compound, or the like may be used in combination as a reaction accelerator during polymerization in the preparation of composite fine particles or microcapsules. When a polyamine compound is used as a component of the polymerizable material, light resistance is not reduced.
It is preferable to use an aliphatic polyamine compound.

The average particle size of the dye precursor-containing composite fine particles and microcapsules used in the present invention is preferably from 0.1 to 15 μm, and more preferably from 0.3 to 6.0 μm, in consideration of the coloring sensitivity. It is more preferable to adjust so that 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 with the dye precursor pulverized into solid fine particles becomes unclear.

By using the composite fine particles in the present invention, it is possible to suppress the background color development due to the pressing force of the dye precursor contained therein and the occurrence of background fogging when white paper is stored for a long period of time. In addition, decoloring of the color image due to heat and humidity can be significantly suppressed.

In the present invention, in order to prepare solid fine particles of the fluoran precursor compound represented by the general formula (I), the compound is prepared by using water as a dispersion medium, a sand grinder, an attritor, a ball mill, a cobo mill or the like. Crushed by various wet crushers, and the crushed fine particles are subjected to modified polyvinyl alcohol such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, and sulfonated polyvinyl alcohol, methylcellulose, carboxymethylcellulose, and styrene-maleic anhydride copolymer salt. And a water-soluble synthetic polymer compound such as a derivative thereof, and, if necessary, a surfactant, an antifoaming agent, and the like, dispersed in a dispersion medium to form a dispersion, and this dispersion is used for preparing a heat-sensitive coloring layer-forming paint. Can be used.
In addition, the fluoran precursor compound is dissolved in a solvent, this solution is emulsified and dispersed in water using the above water-soluble polymer as a stabilizer, and the solvent is evaporated from this emulsion to prepare solid fine particles of the fluoran precursor compound. You can also. In each case, the average particle size of the dispersed particles of the fluoran precursor compound of the formula (I) used in the state of solid fine particles is preferably 0.2 to 3.0 μm in order to obtain appropriate color sensitivity. And more preferably 0.3 to 1.0 μm.

In the present invention, the ratio of the second dye precursor contained in the composite fine particles or microcapsules to the first dye precursor used in the form of solid fine particles is not limited, but generally, the ratio is not limited. With respect to 100 parts by weight of the second dye precursor contained in the fine particles or microcapsules, the amount of the first dye precursor in the form of solid fine particles is from 20 to 6
00 parts by weight, more preferably 50 parts by weight.
３００300 parts by weight.

In the present invention, specific examples of the fluoran precursor compound of the above general formula (I) used as the third dye precursor include, for example, 3- (4'-) Dibutylamino-2'-hydroxyphenyl) -3- (5'-anilino-4'-methyl-2'-methoxyphenyl) phthalide, 3- (4 '
-Diethylamino-2'-hydroxyphenyl) -3-
(5'-anilino-4'-methyl-2'-methoxyphenyl) phthalide, 3- (4'-dibutylamino-2'-
(Hydroxyphenyl) -3- [5 '-(o-chloroanilino) -2'-methoxyphenyl] phthalide, 3-
(4'-ethylisoamylamino-2'-hydroxyphenyl) -3- (5'-anilino-4'-methyl-2 '
-Methoxyphenyl) phthalide, 3- (4'-methylcyclohexylamino-2'-hydroxyphenyl) -3
-(5'-anilino-4'-methyl-2'-methoxyphenyl) phthalide, 3- (4'-dibutylamino-2 '
-Hydroxyphenyl) -3- (5'-anilino-4 '
-Methyl-2'-butoxyphenyl) phthalide and 3- (4'-dibutylamino-2'-hydroxyphenyl) -3- (5'-anilino-4'-methyl-2'-benzyloxyphenyl) phthalide and the like Can be mentioned.

Examples of the fluoran precursor compound which develops a red color include 3- (4'-diethylamino-2'-hydroxyphenyl) -3- (5'-chloro-4'-methyl-
2'-methoxyphenyl) phthalide, 3- (4'-diethylamino-2'-hydroxyphenyl) -3- (5 '
-Chloro-2'-methoxyphenyl) phthalide, 3-
(4'-diethylamino-2'-hydroxyphenyl)
-3- (3'-methoxy-2'-naphthyl) phthalide,
3- (4'-diethylamino-2'-hydroxyphenyl) -3- (1'-methoxy-2'-naphthyl) phthalide, 3- (4'-diethylamino-2'-hydroxyphenyl) -3- (4 '-Chloro-2'-methoxyphenyl) phthalide, 3- (4'-ethyl-p-toluidino-
2'-hydroxyphenyl) -3- (5'-methyl-
2'-methoxyphenyl) phthalide, and 3- (4'-
Isoamyl-ethylamino-2'-hydroxyphenyl) -3- (5'-methyl-2'-methoxyphenyl)
Phthalide and the like can be mentioned.

Examples of the fluoran precursor which develops a blue color include, for example, 3- (4'-diphenylamino-2'-hydroxyphenyl) -3- (4'-diphenylamino-
2'-methoxyphenyl) phthalide.

Examples of the fluoran precursor which develops yellow color include 3- (4'-methoxy-2'-hydroxyphenyl) -3- (4 ', 2'-dimethoxyphenyl) phthalide. These fluoran precursors may be used alone or in combination of two or more.

In the present invention, the ratio of the third dye precursor to the first dye precursor in the form of solid fine particles is not limited. The amount of the first dye precursor in the state is preferably 20 to 600 parts by weight, more preferably 50 to 300 parts by weight.
Parts by weight.

The developer compound used in the present invention is not particularly limited, but generally has a property of liquefying or dissolving with an increase in temperature, and a property of contacting with a dye precursor to form a color. Selected from things. Representative developer compounds include 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol, 4,4'-sec-butylidenediphenol, 4-phenylphenol, 4,4'-dihydroxydiphenylmethane, 4,4'-isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4'-dihydroxydiphenyl sulfide, 4,4 ' -Thiobis (3-methyl-6-te
rt-butylphenol), 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, and bis (3-allyl-4-hydroxyphenyl) sulfone Phenolic compounds can be mentioned.

Further, in the present invention, compounds that can be used as a developer compound include 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, and 4-hydroxybenzoic acid. Phenolic compounds such as -sec-butyl, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 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-
Aromatic carboxylic acids such as benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid, and these phenolic compounds, aromatic carboxylic acids and, for example, zinc, magnesium, aluminum, calcium, etc. And organic acidic substances such as salts with polyvalent metals.

The developer compound used in the present invention is more preferably selected from diphenylsulfone derivatives containing a hydroxyl group in the molecule.
4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4 '
-Isopropoxydiphenyl sulfone, and bis (3
-Allyl-4-hydroxyphenyl) sulfone and the like. Such a developer compound has excellent properties for improving the storage stability of a color image. Such performance is presumed to be due to the strong electron-withdrawing property of the sulfone group in the developer compound. Further, in order to form a color-developed image that is less likely to be decolored even when it comes in contact with oil, a plasticizer, or the like, 4,4′-bis (p-
Toluenesulfonylaminocarbonylamino) diphenylmethane or N- (p-toluenesulfonyl) -N '
Preference is given to using phenylurea.

The developer compound is preferably used in a proportion of 100 to 700% by weight, more preferably 1 to 100% by weight, based on the total weight of the dye precursor and the fluoran precursor compound.
It is used in a proportion of 50 to 400% 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 included in the thermosensitive coloring layer mainly to improve the preservability of the recorded color image. As such an image stabilizer, for example, 1,1,3-tris (2-methyl-4-hydroxy-5
-Cyclohexylphenyl) butane, 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 '-[1,4-phenylenebis (1-methylethylidene)] bisphenol and 4,4'-[1,3
Phenolic compounds such as -phenylenebis (1-methylethylidene)] bisphenol, 4-benzyloxyphenyl-4 '-(2-methyl-2,3-epoxypropyloxy) phenylsulfone, 4- (2-methyl-
Epoxy compounds such as 1,2-epoxyethyl) diphenylsulfone and 4- (2-ethyl-1,2-epoxyethyl) diphenylsulfone, and 1,3,5-tris (2,6-dimethylbenzyl-3-) Hydroxy-4
One or more compounds selected from isocyanuric acid compounds such as (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.

The heat-sensitive coloring layer of the heat-sensitive recording material may contain a heat-fusible substance as a sensitizer in order to adjust the color-forming sensitivity. As a sensitizer,
Compounds conventionally known as sensitizers for heat-sensitive recording materials can be used, for example, parabenzylbiphenyl, dibenzylterephthalate, 1-hydroxy-2-.
Phenyl naphthoate, dibenzyl oxalate, di-o-chlorobenzyl adipate, 1,2-di (3-methylphenoxy) ethane, di-p-methylbenzyl oxalate, di-p-chlorobenzyl oxalate, 2-bis (3,4
-Dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane, and the like. In particular, when di-p-methylbenzyl oxalate and di-p-chlorobenzyl oxalate are used as sensitizers, a sensitizing effect with less fogging can be obtained.

A developer compound used in the present invention,
Additives such as an image stabilizer and a sensitizer are pulverized and dispersed in water in the same manner as when the first dye precursor is used in the form of solid fine particles. What is necessary is just to mix 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. Further, in the same manner as the above-described method for preparing a dye precursor-containing composite fine particle, composite fine particles containing one or more of these compounds are prepared in place of the dye precursor, and this is contained in the thermosensitive coloring layer. You may. The image stabilizer and the sensitizer are the second
It may be contained in composite fine particles or microcapsules containing a dye precursor.

In the present invention, a fine particle 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 (binder) is used as another component material contained in the thermosensitive coloring layer, and if necessary, a crosslinking agent, a wax, a metal soap, a colored dye, a colored pigment, and a fluorescent material. Dyes and the like can be used. 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. Coalesced, acrylamide-acrylate-methacrylate copolymer, styrene-
Water-soluble polymer materials such as maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin and derivatives thereof, as well as polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic ester, and vinyl chloride -Emulsions such as vinyl acetate copolymer, polybutyl methacrylate, and ethylene-vinyl acetate copolymer, and latexes of water-insoluble polymers such as styrene-butadiene copolymer and styrene-butadiene-acrylic copolymer. Can be.

In order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for three-dimensionally curing the adhesive (binder) can 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 waxes added to the thermosensitive coloring layer include 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 background fog.

As the metal soap added to the thermosensitive coloring layer, 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.

In the multicolor heat-sensitive recording material of the present invention, the heat-sensitive color-forming layer can be composed of a plurality of layers in order to record a multicolor image of four or more colors. That is, the thermosensitive coloring layer
A second dye precursor-containing composite fine particle or a second dye precursor-encapsulated microcapsule; a first dye precursor solid fine particle that develops a color different from the second chromogenic dye; and a third dye precursor solid fine particle. A basic heat-sensitive coloring layer containing particles and a color-developing compound; and an additional color-forming dye that develops a color different from the first, second, and third dye precursors in the basic heat-sensitive coloring layer. It comprises at least one additional thermosensitive coloring layer. The additional thermosensitive coloring layer is located above or below the basic thermosensitive coloring layer. Each of the newly provided additional thermosensitive coloring layers needs to contain at least an additional coloring dye and an adhesive, and each of the additional coloring dyes is formed into a composite fine particle or microcapsule in the same manner as described above. It may be contained, or may be used in the form of solid fine particles. Further, the above-mentioned color developing compound, an additive for improving the storage stability of a color image, a sensitizer, a pigment, and the like may be added to the additional thermosensitive coloring layer.

As another method for obtaining a multicolor heat-sensitive recording material capable of heat-sensitive color development of four or more colors, two or more kinds of composite fine particles or microcapsules containing dye precursors that develop colors different from each other are prepared. At this time, by making the average particle diameters different from each other, the coloring sensitivity of these dye precursor-containing composite fine particles or microcapsules is made different from each other. These two or more dye precursor-containing composite fine particles or microcapsules (ie,
Dye precursor-containing composite microparticles or microcapsules, and one or more additional dye precursor-containing composite microparticles or microcapsules), a color developing compound, and a dye precursor in the composite microparticles or microcapsules. The first dye precursor solid fine particles and the third dye precursor solid fine particles that develop different colors are contained in the same thermosensitive coloring layer. Thus, at a low temperature, the first dye precursor in the form of solid fine particles develops a color to form a color image, and at the first medium temperature, the second or additional dye contained in the small-particle composite fine particles or the small-particle microcapsules. A two-color mixed image is formed by the color development of the precursor and the first dye precursor, and at a second intermediate temperature higher than the first intermediate temperature, the first dye precursor, the small-particle composite fine particles or the small-particle microcapsules are formed. And the second or additional dye precursor contained in the large-diameter composite fine particles or the large-diameter microcapsules forms a color to form a three-color mixed image, In the above, the first and second or additional dye precursors and the third dye precursor solid fine particles are colored to form a four-color mixed image. In the same manner as in the case of four colors, the use of three or more kinds of dye precursor-containing composite fine particles or microcapsules having different color developing sensitivities or the use of two or more layers of additional thermosensitive coloring is also used for the multicolor thermosensitive recording material of five or more colors. It can be manufactured by the arrangement of layers.

The type, shape, dimensions, etc. of the support material used in the multicolor heat-sensitive recording material of the present invention are not particularly limited. For example, high quality paper (acidic paper, neutral paper), medium paper, coated paper In addition to paper, art paper, cast-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 higher functions.
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 one is useful for applications such as a three-color heat-sensitive label and a three-color 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. It is desirable that both the protective layer and the undercoat layer are mainly composed 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 improved. Including a plastic pigment, a hollow particle, a foam, or the like in the undercoat layer is effective in improving the coloring sensitivity of the thermosensitive coloring layer formed thereon.

An ultraviolet curable resin on the thermosensitive coloring layer of the present invention,
A protective layer containing an electron beam curable resin can also be provided. Also, printing can be performed on or under the protective layer with UV ink, flexo ink, or the like. Further, when the protective layer contains a release agent such as silicon, the heat-sensitive recording material of the present invention can be used as a linerless pressure-sensitive adhesive label. In this case, a release agent may be applied after printing.

The method for forming each of the above-mentioned 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 on a support using a printing machine or the like, and used. The coating material for the heat-sensitive coloring layer is usually applied to one surface of the support.
２０20 g / m ² (dry) to form a thermosensitive coloring layer. Further, a back layer can be provided on the back surface side of the support for suppressing the penetration of oil or plasticizer from the back surface of the recording material, or for curl control. 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.

[0074]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the scope of the present invention is by no means restricted thereby.

Example 1 Third Dye Precursor (Fluorane Precursor) First Dye Precursor
Body, or other dispersion of the organic compound (1) third dye precursor (fluoran precursor) (high temperature color developing agent) A: 3- (4'-dibutylamino-2'-hydroxyphenyl) -3- (5 '-Anilino-4'-methyl-
2'-methoxyphenyl) phthalide (2) First dye precursor (low-temperature color former) B: 3-diethylamino-7-chlorofluorane (3) Developer compound C: 4,4'-bis (p-toluene Sulfonylaminocarbonylamino) diphenylmethane (4) Sensitizer D: di-p-methylbenzyl oxalate Each of the above organic compounds A to D was mixed with a dispersant in the following mixing ratio, and then this composition was subjected to a vertical process. In a sand mill (manufactured by Imex Co., Ltd., sand grinder), the particles are refined and dispersed so as to have a particle size of 1 μm,
Each dispersion A to D was prepared. Component amount (parts by weight) Each of organic compounds A to D 40 Polyvinyl alcohol 10% solution 40 (polymerization degree 500, saponification degree 90%) Water 20

Composite fine particles containing second dye precursor (medium temperature color former)
Preparation of Fine Particle Dispersion E 6 parts of 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide as a blue dye precursor was added to 100 parts of
Dicyclohexylmethane-4,4 'also heated to
Dissolve in 24 parts of diisocyanate and add 8%
The solution was gradually added to 250 parts of an aqueous solution of polyvinyl alcohol (trade name: Gohsenol GM-14L, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and emulsified and dispersed by stirring at a rotation speed of 5000 rpm using a homogenizer.
A portion was added to homogenize. This emulsified dispersion was heated to 90 ° C. and subjected to a curing reaction for 10 hours to give an average particle size of 2.0 μm.
m, a composite fine particle dispersion E containing a blue coloring dye precursor
Was prepared.

Preparation component (parts by weight) of pigment dispersion F Light calcium carbonate 40 (Brilliant 15, average particle size 0.15 μm, manufactured by Shiraishi Kogyo Co.) 0.7% sodium hexametaphosphate solution 60 Dispersed. Lubricant dispersion
G. Preparation of Adhesive H Solution Further, a 21% aqueous solution of zinc stearate was prepared as a lubricant dispersion G solution, and a 10% aqueous solution of polyvinyl alcohol (NM11, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was prepared as an adhesive H solution.

Preparation of Coating Solution for Thermosensitive Coloring Layer The weight ratio of the above A to H solutions after drying was A: B: C: D:
E: F: G: H = 10: 10: 25: 10: 15: 1
A heat-sensitive layer coating liquid was prepared by blending so as to be 0:10:10. Using a heat-sensitive layer coating solution,
Coating was performed on a high quality paper having a basis weight of 60 g / m ² at a coating amount of 8 g / m ² (dry). After that, a super calendering treatment is performed to obtain a Beck smoothness (JIS-P8) on the surface of the thermosensitive coloring layer.
119) is made to be 150 seconds to 200 seconds,
A multicolor heat-sensitive recording material was obtained.

Example 2 A multicolor heat-sensitive recording sheet was produced in the same manner as in Example 1. However, 3- (4'-dibutylamino-2'-hydroxyphenyl) -3- used in Example 1 was used.
Instead of (5'-anilino-4'-methyl-2'-methoxyphenyl) phthalide, 3- (4'-dibutylamino-2'-hydroxyphenyl) -3- [5 '-(o-
(Chloroanilino) -2'-methoxyphenyl] phthalide was used.

Example 3 A multicolor heat-sensitive recording sheet was produced in the same manner as in Example 1.
However, the 3-diethylamino-7- used in Example 1 was used.
Instead of chlorofluorane, 3-di-n-butylamino-7,8-benzofluoran was used.

Example 4 A multicolor heat-sensitive recording sheet was produced in the same manner as in Example 1.
However, the 3-diethylamino-7- used in Example 1 was used.
Instead of chlorofluorane, 3,6-dimethoxyfluorane was used.

Example 5 A multicolor heat-sensitive recording sheet was produced in the same manner as in Example 1.
However, instead of the composite fine particle dispersion E used in Example 1, a composite fine particle dispersion J prepared by the following procedure was used. Second Dye Precursor-Containing Fine Particle Dispersion J Blue dye precursor 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -4 6 parts of azaphthalide are dissolved in 30 parts of methylene chloride, then 24 parts of dicyclohexylmethane-4,4'-diisocyanate are added and homogeneously mixed, and the mixture is mixed with 5% polyvinyl alcohol ( The solution was gradually added to 250 parts of an aqueous solution (trade name: Gohsenol GM-14L, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and emulsified and dispersed by stirring with a homogenizer at a rotation speed of 5000 rpm. Next, 100 parts of water was added to the emulsified dispersion to make it uniform, and the emulsified dispersion was heated to 90 ° C.
By subjecting the mixture to a curing reaction for a long time, a composite fine particle dispersion J containing a blue color-forming second dye precursor and having an average particle diameter of 1.5 μm was prepared.

Example 6 A multicolor heat-sensitive recording sheet was produced in the same manner as in Example 1.
However, instead of the composite fine particle dispersion E used in Example 1, the second dye precursor-containing microcapsule dispersion K prepared by the following procedure was used. Second Microcapsule Dispersion Containing Dye Precursor K As a blue color-forming dye precursor, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-)
6 parts of diethylaminophenyl) -4-azaphthalide
Dissolve in 20 parts of 1- (3,4-dimethylphenyl) -1-phenylethane, then add 24 parts of dicyclohexylmethane-4,4'-diisocyanate to the solution, mix uniformly, and mix. The solution was washed with 5% polyvinyl alcohol (trade name: Gohsenol GM-, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).
14L) The solution was gradually added to 250 parts of an aqueous solution, and emulsified and dispersed by stirring at a rotation speed of 5000 rpm using a homogenizer. Next, 100 parts of water was added to the emulsified dispersion to homogenize it, the emulsified dispersion was heated to 90 ° C., and subjected to a curing reaction for 10 hours to obtain a blue coloring agent having an average particle diameter of 1.5 μm. A microcapsule dispersion liquid K containing two dye precursors was prepared.

Comparative Example 1 A multicolor heat-sensitive recording sheet was produced in the same manner as in Example 1.
However, the 3-d used as the third dye precursor in Example 1
(4'-dibutylamino-2'-hydroxyphenyl)
Instead of -3- (5'-anilino-4'-methyl-2'-methoxyphenyl) phthalide, 3-dibutylamino-6-methyl-7-anilinofluoran was used.

With respect to the multicolor heat-sensitive recording materials obtained in Test Examples 1 to 6 and Comparative Example 1, a thermosensitive facsimile machine (model: HIFAX-45, manufactured by Hitachi, Ltd.) modified for testing was used.
, Solid line printing of 128 lines under the conditions of one line recording time of 5 msec, scanning line density of 8 lines / mm, and applied energy of 0.8 mJ per dot, low-temperature heating coloring, one line recording time of 5 msec, scanning line density of 8 lines / mm mm, solid printing of 128 lines under the condition of 1.6 mJ of applied energy per dot, medium-temperature heating and coloring, and recording time for one line 5
Solid printing, high-temperature heating and coloring of 128 lines were performed under the conditions of msec, scanning line density of 8 lines / mm, and applied energy of 2.4 mJ per dot. Table 1 shows the colors of the respective images obtained by the respective coloring operations.

The low-temperature, medium-temperature and high-temperature color images obtained in this manner were visually observed for the state of color separation, and evaluated according to the following criteria. ：: A low-temperature coloring image and a medium-temperature coloring image are clear. ×: Partial color mixture of medium-temperature or high-temperature color development in low-temperature color-developed images, or partial color mixture of high-temperature color development in medium-temperature-colored images.

Further, the whiteness of the uncolored portion was measured using a Hunter reflectometer (D type, manufactured by Toyo Seiki Co., Ltd.). Further, as a storage stability test of each multicolor heat-sensitive recording sheet, each uncolored sample was left for 24 hours under the conditions of 40 ° C. and 90% RH, and a Hunter reflectometer (manufactured by Toyo Seiki Co., Ltd .: D type) as described above. The whiteness was measured and the whiteness was recorded after the storage test.

Table 1 shows the results thus obtained. If the whiteness before the storage test is 85% or more and the whiteness after the storage test is 80% or more, there is no practical problem.

[0089]

[Table 1]

[0090]

According to the present invention, it is possible to obtain a multicolor heat-sensitive recording material having high or low whiteness with no or little color mixture due to medium- or high-temperature coloring in low-temperature coloring images during low-temperature printing. It became possible to obtain.

Claims (5)

[Claims] 1. A support, and a support formed on the support.
And are substantially colorless and have different applied energies.
Multiple dye precursors that develop different colors depending on the lug
And reacts with these dye precursors under heat to produce
Multicolor thermosensitive developer containing color developer and binder
A color layer, wherein: (1) a first dye precursor which forms a color at low applied energy;
The body is dispersed in the heat-sensitive coloring layer in the form of solid fine particles.
(2) a second color developing different color from the first dye precursor;
The dye precursor contains a polyvalent isocyanate-containing polymerizable material.
A solvent component, and the second dye precursor.
Oil solution consisting of solute components dissolved in the
Emulsified and dispersed in an aqueous medium, and the weight
By subjecting the compatible raw material to a polymerization reaction and polymerizing it,
Composite obtained by dispersion in the thermosensitive coloring layer
Contained in the fine particles and contained in the composite fine particles.
The second dye precursor contained is finely divided into the first dye precursor fine particles.
A color is formed by an applied energy higher than that of the particles, and (3) an applied energy higher than the second dye precursor
From the first and second dye precursors.
The coloring third dye precursor is converted into the heat-sensitive
Dispersed in a color layer, and the third dye precursor,
The following general formula (I):(However, in the above formula (I), R¹And R^TwoAre
Independently, a hydrogen atom, C₁~ C₆Chain alkyl group, C
_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C ₇~ C
₂₀Aralkyl groups, substituted and unsubstituted phenyl groups,
To C_Two~ C_TenMember selected from the alkoxyalkyl groups of
Wherein R¹And R^TwoAre they combined
Pyrrolidino, piperidino,
And a member selected from morpholino groups
Well, R^ThreeAnd R^FourMeans that one of them is water
Represents a hydrogen atom, the other being a hydrogen atom, C₁~ C₆Chain alk
Group, C_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C
₇~ C₂₀Aralkyl groups, substituted and unsubstituted phenyl groups,
And C_Two~ C_TenOne selected from alkoxyalkyl groups
X¹, X^Two, X^ThreeAnd X^FourAre
Independently, a hydrogen atom, C₁~ C_FourAlkyl group, C₁~
C₈Alkoxyl group, halogen atom, methyl halide
Groups, nitro groups, and substituted and unsubstituted amino groups
And X¹~ X^FourTwo adjacent to each other
And the two carbon atoms of the benzene ring structure to which they are attached
May form a substituted or unsubstituted aromatic cyclic structure
, X^FiveIs a hydrogen atom, C₁~ C₆Alkyl group, C₁~ C
₈Alkoxyl groups, substituted and unsubstituted amino groups, and
Represents a member selected from a halogen atom, and n is 0 or 1 to
4 represents an integer of 4₇~ C₂₀Aralkyl groups,
And each of the substituted phenyl groups independently of the other₁
~ C_FourAlkyl group, C₁~ C₈Alkoxyl groups and positions
At least one position selected from substituted or unsubstituted amino groups
Having a substituent, each of the substituted amino groups
Is C₁~ C₈At least one selected from alkyl groups
Having a substituent of Fluo represented by)
Multicolor feeling characterized by being selected from orchid precursor compounds
Thermal recording material. 2. The thermosensitive coloring layer further includes a fourth dye precursor that develops a color different from the first to third dye precursors, wherein the fourth dye precursor comprises a polyvalent isocyanate-containing polymerization raw material. An oily solution comprising a solvent component containing the fourth dye precursor and a solute component dissolved in the solvent component is emulsified and dispersed in an aqueous medium. The fourth dye precursor obtained by subjecting it to a polymerization reaction and polymerizing the same, contained in the composite fine particles dispersed in the thermosensitive coloring layer, and contained in the composite fine particles. Is higher than the coloring application energy of the first dye precursor fine particles, lower than the coloring application energy of the third dye precursor fine particles, and the second dye precursor contained in the composite fine particles. Color application energy It develops color by different applied energies and over, multicolor heat-sensitive recording material according to claim 1. 3. The thermosensitive coloring layer further includes a fourth dye precursor that develops a color different from the first to third dye precursors, wherein the fourth dye precursor is included in the thermosensitive coloring layer. , Contained in the core of the microcapsules that are dispersed,
The fourth dye precursor contained in the microcapsules is higher than the coloring application energy of the first dye precursor fine particles, lower than the coloring application energy of the third dye precursor fine particles, and 2. The multicolor heat-sensitive recording material according to claim 1, wherein the material develops a color by an applied energy different from an applied energy of the second dye precursor contained in the composite fine particles. 4. A support, and formed on the support.
And are substantially colorless and have different applied energies.
Multiple dye precursors that develop different colors depending on the lug
And reacts with these dye precursors under heat to produce
Multicolor thermosensitive coloring containing a color developer and binder
And (1) a first dye precursor that develops a color with a low applied energy.
Are dispersed in the form of solid fine particles, and (2) a second color developing different color from the first dye precursor.
A dye precursor is dispersed in the thermosensitive coloring layer.
Microcapsules contained in the core of
The second dye precursor in the capsule emits the first dye precursor.
Color is developed with applied energy higher than color applied energy
And (3) the applied energy is higher than that of the second dye precursor.
Colors different from those of the first and second dye precursors
The third dye precursor is converted into the heat-sensitive color in the form of solid fine particles.
Dispersed in a layer and the third dye precursor is
The general formula (I):(However, in the above formula (I), R¹And R^TwoAre
Independently, a hydrogen atom, C₁~ C₆Chain alkyl group, C
_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C₇~ C₂₀
Aralkyl groups, substituted and unsubstituted phenyl groups, and C
_Two~ C_TenLists members selected from alkoxyalkyl groups
Provided that R¹And R^TwoAre they combined
Along with the nitrogen atom, pyrrolidino, piperidino and
And morpholino groups.
K, R^ThreeAnd R^FourMeans that one of them is a hydrogen source
And the other is a hydrogen atom, C₁~ C₆Chain alkyl
Group, C_Three~ C₆Cyclic alkyl groups, substituted and unsubstituted C₇
~ C₂₀Aralkyl groups, substituted and unsubstituted phenyl groups,
C_Two~ C_TenMember selected from alkoxyalkyl group
And X¹, X^Two, X^ThreeAnd X^FourAre each other
Independently of the hydrogen atom, C₁~ C_FourAlkyl group, C₁~ C
₈Alkoxyl group, halogen atom, methyl halide
Groups, nitro groups, and substituted and unsubstituted amino groups
And X¹~ X^FourTwo adjacent to each other
Together with the carbon atom of the benzene ring structure to which they are attached.
Or a substituted or unsubstituted aromatic cyclic structure;
^FiveIs a hydrogen atom, C ₁~ C₆Alkyl group, C₁~ C₈Al
Coxyl groups, substituted and unsubstituted amino groups, and halogenated
N represents a member selected from the group consisting of
The substitution C₇~ C₂₀Aralkyl groups and substitutions
Each of the phenyl groups is independently of the other₁~ C_FourA
Alkyl group, C₁~ C₈Alkoxyl group and substitution and
At least one substituent selected from unsubstituted amino groups
Wherein each of the substituted amino groups is C
₁~ C₈Has one or more substituents selected from alkyl groups
Is what you do. ) Represented by the fluoran precursor
A multicolor heat-sensitive recording material characterized by being selected from compounds. 5. The thermosensitive coloring layer further includes a fourth dye precursor that develops a color different from the first to third dye precursors, and the fourth dye precursor is dispersed in the thermosensitive coloring layer. Wherein the fourth dye precursor contained in the core of the microcapsule is higher than the coloring application energy of the first dye precursor fine particles, and the third dye precursor is contained in the third dye precursor. 5. The multicolor heat-sensitive recording material according to claim 4, wherein the material develops a color by an applied energy that is lower than the coloring application energy of the body fine particles and is different from the coloring application energy of the second dye precursor contained in the microcapsules.