JP2001239760A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material which produces a sharp multi-color image of high density free from a color mixture by application of a comparatively lower heat energy and is of a multi-color color development type with high sensitivity and superb color separation properties and further can be manufactured at a low cost in a simple process. SOLUTION: This heat-sensitive recording material has a heat-sensitive recording layer containing together two kinds or more of an electron donative dye precursors which develop into a varying hue and an electron receptive compound, formed on a support. At least one of the two kinds or more of the electron donative dye precursor is contained in the heat-sensitive recording layer in a state of solid fine particles and at least the other kind is contained in the heat-sensitive recording layer in such a state that it is encapsulated in a microcapsule. In addition, at least either of the support or the heat-sensitive recording layer has a different hue from the hue developed by a chemical reaction between the electron donative dye precursor and the electron receptive compound as the characteristics of the heater-sensitive recording material.

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 material, and more particularly, to a heat-sensitive recording material capable of forming a multi-color image excellent in color separation with a simple layer structure.

[0002]

2. Description of the Related Art Thermal recording methods are: 1) no development is required; 2) when the support is paper, the paper quality is close to that of ordinary paper;
It has advantages such as easy handling, 4) high color density, 5) simple and inexpensive recording device, and 6) no noise during recording. Applications of thermal recording, such as in the field of labels in POS, etc., are also expanding. Against this background, in recent years, the shift to multi-color images has progressed rapidly, and there has been a high demand for multi-color heat-sensitive recording materials which can be directly recorded by a thermal head. In order to respond to the above demand, recently, for example, a support has microcapsules encapsulating a color former such as an electron-donating dye precursor, and is laminated with two or more monochromatic heat-sensitive recording layers that develop different colors. A multi-layer heat-sensitive recording material that forms a multicolor image has been developed.

[0003] However, such a multilayer thermal recording material,
Like the monochromatic recording material, it has excellent storage stability, but it adopts microcapsules for each layer and the layer thickness of the entire recording layer is increased by lamination, so that the lower layer close to the support is colored sufficiently. To do so, it is necessary to apply high thermal energy. Generally, a heating device such as a thermal head is used to form an image using a thermosensitive recording material. However, if heat is repeatedly applied under high energy, the load applied to the head is large and the durability of the head is reduced. In addition, if sufficient heat is not applied, the color-forming reactivity decreases, and it is difficult to obtain a clear image. Furthermore, under the application of high thermal energy, there is a certain limit in the thermal controllability, which hinders the increase in recording speed, and it is difficult to control the temperature of the head delicately. It is difficult to obtain a clear, high-contrast image that is likely to occur.

In recent years, the quality of output images based on digital signals has been increasing, and even images using thermal recording materials have no exception for multicolor images that are excellent in color separation and are clear and have high contrast. High demand. Therefore, high sensitivity is indispensable even in a multicolor coloring type thermosensitive recording material, and there has been a need to establish a technique capable of forming a clear and high-contrast image with excellent color separation.

[0005] In order to meet the above-mentioned demands, studies on increasing the sensitivity of the heat-sensitive recording material itself and the like have been actively conducted. Although research has been carried out, it has not yet been possible to sufficiently achieve high sensitivity and vividness of a multicolor heat-sensitive recording material. On the other hand, in the case of a multilayer recording material in which heat-sensitive recording layers are laminated, it has been difficult to simplify the manufacturing process and to realize a reduction in cost.

As described above, by performing thermal printing with a low applied energy, a clear multicolor image with high density and no color mixture can be obtained, and it can be manufactured in a simple process at low cost, and has high sensitivity and color separation. At present, a multicolor developing type heat-sensitive recording material having excellent (color reproducibility) has not yet been provided.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention provides a high-sensitivity, color-separating and contrasting image which can be produced at a high density and is free of color mixture by application of relatively low heat energy, and which can be produced at a low cost by a simple process. It is an object of the present invention to provide a multi-color heat-sensitive recording material having excellent thermal characteristics.

[0008]

Means for solving the above problems are as follows. That is, <1> a heat-sensitive recording material having a heat-sensitive recording layer containing, on a support, two or more kinds of electron-donating dye precursors capable of developing different colors and an electron-accepting compound in the same layer. At least one of the two or more electron-donating dye precursors is contained in the heat-sensitive recording layer in a solid fine particle state, and at least one is contained in the heat-sensitive recording layer in a state of being encapsulated in microcapsules. Wherein at least one of the support and the thermosensitive recording layer has a hue different from a hue that develops color by a reaction between the electron donating dye precursor and the electron accepting compound. It is.

That is, among two or more kinds of electron-donating dye precursors capable of forming different colors, an electron-donating dye precursor contained in a solid fine particle state (hereinafter referred to as a “first electron-donating dye precursor”) ) Is an electron-donating dye precursor (hereinafter, referred to as a “second electron-donating dye precursor”) that reacts with an electron-accepting compound in a low-temperature region to form a color and is encapsulated in microcapsules. ) Reacts with the electron-accepting compound in a higher temperature region to develop colors different from each other (hereinafter, the hue at the time of color development of the electron-donating dye precursor is referred to as “colored hue”). .). Since the first electron-donating dye precursor and the second electron-donating dye precursor have different hues when colored, a multicolor image is formed by changing the temperature applied during image recording. be able to. Further, in the heat-sensitive recording material of the present invention, the support is a support having a hue in advance, or the heat-sensitive recording layer is a heat-sensitive recording layer having a hue in advance, or both have a hue in advance. A multicolor image can be formed with a simple configuration. The hue of at least one of the support and the heat-sensitive recording layer is a hue different from the hue generated by the reaction between the electron-donating dye precursor and the electron-accepting compound in the heat-sensitive recording layer.

<2> A heat-sensitive recording layer comprising, on a support, two or more kinds of electron-donating dye precursors capable of coloring in different hues and an electron-accepting compound in the same layer. A thermosensitive recording material having a protective layer on a recording layer, wherein at least one of the two or more electron-donating dye precursors is used.
Species are contained in the heat-sensitive recording layer in the form of solid fine particles, at least one kind is contained in the heat-sensitive recording layer in a state of being encapsulated in microcapsules, and at least one of the support, the heat-sensitive recording layer and the protective layer is A heat-sensitive recording material having a color different from the color developed by the reaction between the electron-donating dye precursor and the electron-accepting compound. That is, when the heat-sensitive recording material of the present invention has a protective layer on the heat-sensitive recording layer, only the protective layer has a hue different from the color hue, or the protective layer and another member (support and / or heat-sensitive recording medium). Layer) has a hue different from the color hue, so that a multicolor image can be formed with a simple configuration.

<3> An undercoat layer is provided on a support, and on the undercoat layer, two or more kinds of electron-donating dye precursors capable of developing different colors and an electron-accepting compound are contained in the same layer. A heat-sensitive recording material having a heat-sensitive recording layer containing at least one of the two or more electron-donating dye precursors.
The seed is contained in the heat-sensitive recording layer in a solid fine particle state, at least one kind is contained in the heat-sensitive recording layer in a state encapsulated in microcapsules, and at least one of the support, the undercoat layer, and the heat-sensitive recording layer A heat-sensitive recording material having a color different from the color developed by the reaction between the electron-donating dye precursor and the electron-accepting compound. That is, when the heat-sensitive recording material of the present invention has an undercoat layer on a support, only the undercoat layer has a hue different from the color hue, or the undercoat layer and another member (support and / or heat-sensitive recording layer). ) Has a hue different from the color hue, so that a multicolor image can be formed with a simple configuration.

<4> Any one of the above items <1> to <3>, wherein the volume average particle diameter of the electron-donating dye precursor and the electron-accepting compound contained in the solid fine particle state is 1.0 μm or less, respectively. The heat-sensitive recording material described in Crab. <5> The capsule wall according to <1>, wherein the capsule wall of the microcapsule contains polyurethane and / or polyurea as a component.
> To <4>.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The heat-sensitive recording material of the present invention comprises a heat-sensitive recording material of the first invention, a heat-sensitive recording material of the second invention,
Of the invention. -Thermal recording material of the first invention- The thermal recording material of the first invention has a heat-sensitive recording layer on a support, and further has other layers as necessary.
Here, at least one of the support and the heat-sensitive recording layer has a hue (hereinafter, referred to as a hue) different from the color hue in the heat-sensitive recording layer.
This is referred to as the "base color". )have. By having a base color in advance before reacting the electron-donating dye precursor with the electron-accepting compound, the color can be increased by one color with a simple configuration. Further, for example, the color of the base is made pale, and first, by applying low heat energy, the electron donor dye precursor and the electron accepting compound in the state of solid fine particles are caused to react with each other, so that the color is slightly darker than the base color. Prints a background image (including characters) with the application of a higher thermal energy, and reacts the electron-donating dye precursor encapsulated in the microcapsules with the electron-accepting compound to produce another image with a darker color By printing (including characters), the operation of printing another image on a support such as paper on which a background image has been printed can be simplified, and the background image is not printed. And the like, a background image and an image different from the background image can be printed. Therefore, for example, it can be used in various fields such as supermarket receipts and bank cash dispensers.

The colors in chromatics include an achromatic color consisting only of lightness belonging to the white, gray and black systems, and a chromatic color consisting of three elements of hue, lightness and saturation such as red, yellow and green. is there. In the present invention, the hue (base color) different from the color hue in the heat-sensitive recording layer means a chromatic color and does not include an achromatic color. That is, for example, when the support is white or transparent,
The object of the present invention, which is to form a multicolor image with a simple configuration, cannot be achieved, which is the same as that conventionally used. Further, for example, when the support is black, even if the color is formed by the reaction between the electron-donating dye precursor and the electron-donating dye precursor, the formed hue is inconspicuous, and a multicolor image is formed. Can not.

-Thermal recording material of the second invention- The thermal recording material of the second invention has a heat-sensitive recording layer and a protective layer on a support in this order, and further includes other layers as necessary. Have. The heat-sensitive recording material of the second invention comprises
The protective layer is an essential component as compared with the heat-sensitive recording material of the invention. Here, at least one of the support, the heat-sensitive recording layer, and the protective layer has a hue (base color) different from the color hue in the heat-sensitive recording layer. Therefore, only the protective layer may have a base color, or the protective layer and another member (support and / or thermosensitive recording layer) may have a base color.

-Thermal recording material of the third invention- The thermal recording material of the third invention has an undercoat layer and a heat-sensitive recording layer on a support in this order, and further comprises other layers, if necessary. Have. The thermosensitive recording material of the third invention has an undercoat layer as an essential component as compared with the thermosensitive recording material of the first invention. Here, at least one of the support, the undercoat layer and the heat-sensitive recording layer has a hue (base color) different from the color hue in the heat-sensitive recording layer. Therefore, only the undercoat layer may have a base color, or the undercoat layer and another member (support and / or thermosensitive recording layer) may have a base color.

Hereinafter, the constitution of the heat-sensitive recording material of the first to third inventions will be described. [Thermal Recording Layer] The thermosensitive recording layer contains an electron-donating dye precursor and an electron-accepting compound, and further contains other components as necessary. When heat is supplied to the heat-sensitive recording material of the present invention by a heating means such as a thermal head, the temperature of the heat-supplied region in the heat-sensitive recording layer is changed to the first electron-donating dye precursor in the form of solid fine particles and / or electron-accepting compound is temperatures T ₁ for melting. The molten first electron-donating dye precursor reacts with an electron-accepting compound present in the vicinity to develop a specific hue.
Next, when the amount of heat supplied from the heating means to the heat-sensitive recording layer is increased, the temperature of the heat-supplied region in the heat-sensitive recording layer changes from the material non-permeability of the microcapsule wall to the material permeation. The obtained temperature T ₂ (T ₁ <T ₂ ). The second electron-donating dye precursor encapsulated in the microcapsules that have changed to the material permeability is formed by the penetration of an electron-accepting compound present in the vicinity of the microcapsules (and / or the second electron-donating dye). When the donor dye precursor diffuses out of the microcapsule, it comes into contact with and reacts with the electron accepting compound present in the vicinity, and develops a specific hue. On the other hand, at the temperature T ₂ , the first electron-donating dye precursor also develops a color due to the reaction with the electron-accepting compound. Therefore, the region at the temperature T ₂ includes the first electron-donating dye precursor and the second electron-donating dye. A hue in which the coloring hues of the donor dye precursor are mixed is exhibited.

The heat-sensitive recording material of the present invention can change the color of the first electron-donating dye precursor and the color of the first electron-donating dye precursor by changing the amount of heat supplied from the heating means during image recording. A multicolor image can be formed in which a hue in which the coloring hue and the coloring hue of the second electron-donating dye precursor are mixed is exhibited.

When the heat-sensitive recording layer further contains another kind of electron-donating dye precursor (third electron-donating dye precursor), the third electron-donating dye precursor is microcapsules. It is preferable to include the thermosensitive recording layer in a state of being included in the thermosensitive recording layer. The microcapsules encapsulating the third electron-donating dye precursor are thermally responsive (from non-permeability to material-permeability) to a different temperature region than the microcapsules encapsulating the second electron-donating dye precursor. (Which changes). For example, thermal responsiveness can be changed by using microcapsules made of materials having mutually different glass transition points.

As the glass transition point of each microcapsule, the glass transition point between the microcapsules is controlled from the viewpoint of controlling the coloring properties of the second and subsequent colors and making the coloring hue a sharp color-separated hue. It is preferable that the temperature difference is 20 ° C. or more. Therefore, it is preferable to select the wall material so that the glass transition temperature difference between the capsule walls is 20 ° C. or more. When the temperature difference of the glass transition point is less than 20 ° C., before the second electron-donating dye precursor encapsulated in the microcapsule having the glass transition point in the low temperature region completes the color-forming reaction, the temperature difference in the higher temperature region is reduced. The color development reaction of the third electron-donating dye precursor encapsulated in the microcapsules having a glass transition point is started to cause color mixing, and it is impossible to obtain a clear multicolor image excellent in color separation. is there.

In the case where an image is formed using the heat-sensitive recording material having the above-described structure, the temperature of the heat-sensitive recording layer is set to a temperature T ₁ and further to a temperature T ₂ by supplying heat from a heating means in the same manner as described above. Form an image. Thereafter, by further increasing the amount of heat supplied from the heating means, the temperature of the heat-supplied region in the heat-sensitive recording layer is changed so that the microcapsules containing the third electron-donating dye precursor become material-permeable. Temperature T ₃ (T ₂ <T ₃ ). The third electron-donating dye precursor encapsulated in the microcapsules that have changed to the material permeability is formed by the permeation of an electron-accepting compound present in the vicinity of the microcapsules (and / or
Alternatively, the third electron-donating dye precursor comes into contact with a nearby electron-accepting compound (due to diffusion outside the microcapsule) and reacts to form a specific hue. On the other hand, at the temperature T ₃ , the first electron-donating dye precursor and the second electron-donating dye precursor also react with the electron-accepting compound to form a color, so that the region at the temperature T ₃ is the first temperature. A hue in which the coloring hues of the electron-donating dye precursor, the second electron-donating dye precursor, and the third electron-donating dye precursor are mixed is exhibited.

In the heat-sensitive recording material of the present invention, the color hue of the electron-donating dye precursor contained in the heat-sensitive recording layer is not particularly limited. The first electron-donating dye precursor that forms a color in the low-temperature region exhibits a hue as a mixture of the above hues, and the first electron-donating dye precursor emits a light color, and the electron-donating dye precursor develops a dark hue in order of increasing temperature. (A second electron-donating dye precursor and, if desired, a third electron-donating dye precursor, etc.) are preferably selected. That is, for example, when three kinds of electron donating dye precursors are contained, in order from the electron donating dye precursor that develops color in the lowest temperature range, yellow-red-black, red-blue-
It is preferable to select an electron-donating dye precursor so as to develop a black color or the like. These electron donor dye precursors need not be a single compound, but may be a mixture of two or more compounds.

The heat-sensitive recording layer in the present invention is a laminated heat-sensitive recording layer in which a layer containing two or more kinds of electron-donating dye precursors and an electron-accepting compound and the other layers are laminated in the same layer. It may be.

When the heat-sensitive recording layer has a base color as described above, the method of applying the base color to the heat-sensitive recording layer is not particularly limited, but a colored dye or a colored pigment may be used. Is preferred. Colored dyes to be used include direct dyes, basic dyes, acid dyes and the like. As the direct dye, an azo dye is typical, and in particular, disazo and trisazo dyes are often used, but of course, the present invention is not limited to these.

Examples of the colored pigments include iron oxide pigments, zinc sulfide compounds, coper phthalocyanine blue, copearl polybrolophthalocyanine blue, industrone blue, and isodibenzatron violet, but are not limited thereto. is not. These colored dyes and colored pigments may be used alone or in combination of two or more.

The content of the colored dye and the colored pigment in the heat-sensitive recording layer can be appropriately selected according to the purpose. In general, these colored dyes and the colored pigment are used per 1 m ² of the support. 0.001 to 1.0
1 g.

A specific method for imparting a base color to the heat-sensitive recording layer is as follows. In preparing a dispersion of the electron-donating dye precursor in the form of solid fine particles, the colored dye or the colored pigment may be added. When preparing a dispersion of the electron-accepting compound, the colored dye or the colored pigment may be added.When the dispersion and the electron-donating dye precursor-encapsulated microcapsule dispersion are mixed, the colored dye or the colored pigment may be added. Dyes or colored pigments may be added. The method for coloring the heat-sensitive recording layer with a base color is not limited to the above method.

(Electron-donating Dye Precursor) Examples of the electron-donating dye precursor contained in the heat-sensitive recording layer include the following compounds. Examples of the electron-donating dye precursor that emits black color include 3-di (n-butylamino).
-6-methyl-7-anilinofluoran, 2-anilino-3-methyl-6-N-ethyl-N-sec-butylaminofluoran, 3-di (n-pentylamino) -6
Methyl-7-anilinofluoran, 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3- (Nn-hexyl-N-ethylamino) -6 Methyl-7-anilinofluoran, 3- [N
-(3-ethoxypropyl) -N-ethylamino) -6
-Methyl-7-anilinofluoran, 3-di (n-butylamino) -7- (2-chloroanilino) fluoran,
3-diethylamino-7- (2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofur Oran and the like.

Among them, in terms of background fog in the non-image area, 3
-Di (n-butylamino) -6-methyl-7-anilinofluoran and 2-anilino-3-methyl-6-N-ethyl-N-sec-butylaminofluoran are preferred.

Examples of the electron-donating dye precursor which develops a red, magenta, or orange color system include, for example, 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-bromofluoran, 3-diethylamino-7,8-benzofluoran,
3-diethylamino-6,8-dimethylfluoran, 3
-Diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7-tert-butylfluoran, 3- (N-ethyl-N-tolylamino) -7-methylfluoran, 3- (N-ethyl- N-tolylamino) -7-ethylfluoran;

3- (N-ethyl-N-isobutylamino) -6-methyl-7-chlorofluoran, 3- (N-
Ethyl-N-isoamylamino) -7,8-benzofluoran, 3-cyclohexylamino-6-chlorofluoran, 3-di-n-butylamino-6-methyl-7-bromofluoran, 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-carbobutoxyanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-formylanilino)
-3-methyl-6-di-n-butylaminofluoran,

2- (N-benzylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-
Allylanilino) -3-methyl-6-di-n-butylaminofluoran, 2- (N-methylanilino) -3-methyl-6-di-n-butylaminofluoran, 3,3 ′
-Bis (1-n-butyl-2-methylindole-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], 7- (N-ethyl-N-
n-hexylamino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] virazole) -4,3′-phthalide] and the like.

Among these, the electron-donating dye precursors that emit red in terms of color sensitivity and background fog include 3-diethylamino-7-chlorofluorane and 3-diethylamino-6-methyl-7-chlorofluoran. Etc. are preferred,
Examples of the electron-donating dye precursor that emits a purple-red color include 3,
3'-bis (1-n-butyl-2-methylindole-
3-yl) phthalide and the like are preferable, and examples of the electron-donating dye precursor which develops an orange color include 3-cyclohexylamino-6-chlorofluoran and 3-diethylamino-
6,8-dimethylfluoran, 7- (N-ethyl-N-
Isoamylamino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-C] pyrazo-
Ru) -4,3'-phthalide] and the like.

In particular, when a dye precursor capable of forming a red color is used as the electron-donating dye precursor, a red-color-forming dye precursor having a slightly different color tone is mixed and used for the purpose of color tone correction. Is preferred. For example, 3-diethylamino-7-chlorofluoran or 3-diethylamino-
6-methyl-7-chlorofluorane has 3,3′-bis (1-n-butyl-2-methylindol-3-yl)
By adding a small amount of a coloring dye having a reddish-brown color tone such as phthalide or 3,3'-bis (1-ethyl-2-methylindol-3-yl) phthalide, a color tone with a strong reddish color is obtained. Color tone can be adjusted.

Examples of the electron-donating dye precursor that emits blue light include crystal violet lactone and 3-
(4-diethylamino-2-ethoxyphenyl) -3-
(1-ethyl-2-methylindol-3-yl) -4
-Azaphthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylamino Phthalide,
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-methylindole-3- Yl) -3- (2-n-
Hexyloxy-4-diethylaminophenyl) -4-
Azaphthalide, 3-diphenylamino-6-diphenylaminofluoran and the like can be mentioned.

Above all, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide is preferred from the viewpoint of background fog, and from the viewpoint of image preservability, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-
Methylindol-3-yl) -4-azaphthalide is preferred.

Examples of the electron-donating dye precursor that emits green light include 3- (N-ethyl-Nn-hexylamino) -7-anilinofluoran and 3-diethylamino-7-dibenzylaminofuran. Oran, 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-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 ′-(6 ′
-Dimethylamino) phthalide and the like.

Among them, from the viewpoint of image preservation, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-
(6′-Dimethylamino) phthalide is preferred.

Examples of the electron-donating dye precursor that emits yellow color include, for example, 3,6-dimethoxyfluoran, 1-
(4-n-dodecyloxy-3-methoxyphenyl)-
2- (2-quinolyl) ethylene, 1,3-bis- (4-
Dimethylaminophenyl) -3-bis (ethoxycarbonyl) methyl-1-propene, 2-phenyl-4-
(4′-dimethylaminophenyl) -6- (2′-octyloxyphenyl) -pyridine, spiro [4H-3,
1-benzoxazine-4,9 ′-[9H] xanthon] -3 ′, 6′-bis (hexyloxy) -2-phenyl, spiro [4H-3,1-benzoxazine-4,
9 ′-[9H] xanthon] -3 ′, 6′-bis (hexyloxy) -2- (thienyl) and the like. Each of these electron donating dye precursors may be used alone, but it is more effective to use them for color tone correction.

The volume average particle diameter of the electron donating dye precursor in the form of solid fine particles is preferably 1.0 μm or less,
0.7 μm is more preferred. When the volume average particle size is 1.
If it exceeds 0 μm, the thermal sensitivity may decrease. Here, the electron-donating dye precursor in the form of solid fine particles refers to fine particles in which a water-soluble polymer compound such as polyvinyl alcohol is adsorbed on the surface of the crystal of the electron-donating dye precursor. The volume average particle diameter of the solid fine particles can be measured by a laser diffraction type particle size distribution analyzer or the like.

In the heat-sensitive recording layer, the content of the electron-donating dye precursor contained in the form of solid fine particles is 0.05 to 1.0.
preferably ^{g / m 2, 0.1~0.5g / m} 2 is more preferable. When the content is less than 0.05 g / m ^2, sometimes coloring density is low, when it exceeds 1.0 g / m ^2, the fog density of non-image area may be increased.

The content of the electron-donating dye precursor contained in the heat-sensitive recording layer in a state of being encapsulated in the microcapsules is preferably 0.05 to 1.0 g / m ² per one kind. 0.1 to 0.5 g / m ² is more preferable. When the content is less than 0.05 g / m ^2, sometimes coloring density is low, when it exceeds 1.0 g / m ^2, the fog density of non-image area may be increased. However, the preferable content of the electron-donating dye precursor in the heat-sensitive recording layer depends on the color hue or the color tone of the second and subsequent colors, and is not limited to the above range.

(Electron-Accepting Compound) The electron-accepting compound contained in the heat-sensitive recording layer reacts with the electron-donating dye precursor by receiving heat to form the electron-donating dye precursor. It is a compound that develops color and functions as a color developer. Examples of the electron-accepting compound include phenol derivatives, phenol resins, novolak resins, metal-treated novolak resins, metal complexes, salicylic acid derivatives,
Examples thereof include a metal salt of an aromatic carboxylic acid, acid clay, bentonite, and the like. Specific examples include Japanese Patent Publication No. 40-9309, Japanese Patent Publication No. 45-14039, and Japanese Patent Application Laid-Open No. Sho 52-140483.
JP-A-48-51510, JP-A-57-2108
No. 86, JP-A-58-87089, JP-A-59-11
No. 286, Japanese Unexamined Patent Publication No.
No. 95988, JP-A-63-65779, JP-A-6-609
72984 and JP-A-7-278098. Among the above compounds, compounds represented by the following general formula (I) are preferred in that good color-forming properties can be obtained and storage stability (fog density, chemical resistance) of non-image areas and image areas can be improved. Particularly preferred.

[0044]

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In the general formula (I), R represents a group having 1 to 2 carbon atoms.
An alkyl group having 0, an aralkyl group having 7 to 25 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylcarbonyl group having 5 to 20 carbon atoms, an arylcarbonyl group having 7 to 20 carbon atoms,
An alkylsulfonyl group having 4 to 20 carbon atoms or 6 to 6 carbon atoms
20 represents an arylsulfonyl group.

As the alkyl group having 1 to 20 carbon atoms, for example, isopropyl group, n-hexyl group, m-octyl group and the like are preferably exemplified. As the aralkyl group having 7 to 25 carbon atoms, for example, Preferable examples include a benzyl group and an isopropylbenzyl group. 6 to 2 carbon atoms
The aryl group of 0 preferably includes, for example, a phenyl group and a tolyl group, and the alkylcarbonyl group having 5 to 20 carbon atoms preferably includes, for example, a butoxyethyl group. Further, as the arylcarbonyl group having 7 to 20 carbon atoms, for example, a phenoxyethyl group and the like are preferably mentioned, and as the alkylsulfonyl group having 4 to 20 carbon atoms, for example, a hexadecylsulfonyl group and the like are suitably used. Preferable examples of the arylsulfonyl group having 6 to 20 carbon atoms include a toluenesulfonyl group.

Specific examples of the electron accepting compound represented by the above general formula (I) include 4-hydroxyphenyl-4 ′
-Isopropyloxyphenylsulfone, 4-hydroxyphenyl-4'-n-hexyloxyphenylsulfone, 4-hydroxyphenyl-4'-n-octyloxyphenylsulfone, 4-hydroxyphenyl-4'-
n-decyloxyphenyl sulfone, 4-hydroxyphenyl-4′-n-dodecyloxyphenyl sulfone,
4-hydroxyphenyl-4′-benzyloxyphenylsulfone, 4-hydroxyphenyl-4′-p-isopropylbenzyloxyphenylsulfone, 4-hydroxyphenyl-4′-β-phenethyloxyphenylsulfone, 4-hydroxyphenyl-4 '-Β-phenethyloxyphenyl sulfone, 4-hydroxyphenyl-
4′-β-ethoxyethyloxyphenyl sulfone,

4-hydroxyphenyl-4'-β-phenoxyethyloxyphenylsulfone, 4-hydroxyphenyl-4'-o-chlorobenzoyloxyphenylsulfone, 4-hydroxyphenyl-4'-β-t-butylbenzoyloxy Phenylsulfone, 4-hydroxyphenyl-4'-lauroyloxyphenylsulfone, 4-hydroxyphenyl-4'-decanoyloxyphenylsulfone, 4-hydroxyphenyl-4'-myristoyloxyphenylsulfone, 4-hydroxyphenyl-4 '-Stearyloxyphenyl sulfone, 4
-Hydroxyphenyl-4′-β-phenoxypropionyloxyphenylsulfone, 4-hydroxyphenyl-4′-hexadecylsulfonyloxyphenylsulfone, 4-hydroxyphenyl-4′-decylsulfonyloxyphenylsulfone,

4-hydroxyphenyl-4'-p-toluenesulfonyloxyphenylsulfone, 4-hydroxyphenyl-4'-p-isopropylbenzenesulfonyloxyphenylsulfone, 4-hydroxyphenyl-
4 '-(4-pt-butylphenoxybutyloxy)
Phenyl sulfone, 4-hydroxyphenyl-4'-
(4-pt-aminophenoxybutyloxy) phenyl sulfone, 4-hydroxyphenyl-4 ′-(5-p
-T-butylphenoxyamyloxy) phenylsulfone, 4-hydroxyphenyl-4 '-(6-pt-butylphenoxyhexyloxy) phenylsulfone and the like are preferred. Among these, 4-hydroxyphenyl-4′-isopropyloxyphenyl sulfone,
4-Hydroxyphenyl-4'-benzyloxyphenylsulfone, 4-hydroxyphenyl-4'-octyloxyphenylsulfone and the like are preferred.

In the present invention, the electron accepting compound represented by the general formula (I) may be used alone or in combination of two or more. Further, the electron accepting compound represented by the general formula (I) can be used in combination with the other electron accepting compounds described above.

In the thermosensitive recording layer, the electron accepting compound is preferably contained in the form of solid fine particles. When the solid fine particles state, the volume average particle diameter of the fine particles,
1.0 μm or less is preferable, and 0.5 to 0.7 μm is more preferable. If the volume average particle size exceeds 1.0 μm, the thermal sensitivity may decrease. Further, the electron-accepting compound, after increasing the transparency of the heat-sensitive recording layer, from the viewpoint of improving the image quality, after dissolving in a water-insoluble or insoluble organic solvent, a water-soluble polymer, and If necessary, it can also be used as an emulsified dispersion which is emulsified by adding it to an aqueous phase containing a surfactant. Here, as the organic solvent, the water-soluble polymer, and the surfactant, the same ones that can be used for preparing a microcapsule dispersion described below can be used.

The content (dry weight) of the electron-accepting compound in the heat-sensitive recording layer is determined based on the amount of the electron-donating dye precursor 100
50 to 400 parts by weight, preferably 100 parts by weight,
-300 parts by weight is more preferred. If the content is less than 50 parts by weight, the thermal sensitivity of the heat-sensitive recording layer may be reduced, and the fog density of the non-image portion may be increased due to long-term storage. There is a case where the matching property between the thermal head and the thermal head is deteriorated.

(Other Components) In the heat-sensitive recording material of the present invention, at least one of the following general formulas (II) and (III) is preferably contained in the heat-sensitive recording layer as a sensitizer. It is preferable to include the sensitizer since sensitivity is improved.

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In the general formula (II), R ¹ represents an aralkyl group and may be unsubstituted or have a substituent. Examples of the aralkyl group include a benzyl group and a substituted benzyl group, and examples of the substituent include an alkyl group and a halogen atom.

Specific examples of the compound represented by the general formula (II) include, for example, 1-benzyloxynaphthalene,
2-benzyloxynaphthalene, 2-p-methylbenzyloxynaphthalene, 2-p-chlorobenzyloxynaphthalene and the like can be mentioned. However, the present invention is not limited to these.

[0057]

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In the general formula (III), R ² and R ³ each independently represent an alkyl group or an alkoxyl group.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group.

Specific examples of the compound represented by the general formula (III) include, for example, 1,2-diphenoxymethylbenzene, 1,4-diphenoxymethylbenzene,
-Di- (4-methylphenoxy) methylbenzene and the like. However, the present invention is not limited to these. These may be used alone or in combination of two or more.

The sensitizer represented by the general formula (II) and / or
Alternatively, when the sensitizer represented by the general formula (III) is used, the sensitizer is preferably used in the form of a solid dispersion.
The volume average particle size of the sensitizer used is preferably 1.0 μm or less, more preferably 0.5 to 0.7 μm. When the volume average particle size exceeds 1.0 μm, the thermal sensitivity may be reduced.

The content of the compound represented by the general formula (II) and / or the compound represented by the general formula (III) in the thermosensitive recording layer is based on 100 parts by weight of the electron-donating dye precursor. 50 to 500 parts by weight is preferable, and 75 to 30 parts by weight.
0 parts by weight is more preferred. If the content is less than 50 parts by weight, the thermal sensitivity of the heat-sensitive recording material may decrease. If the content exceeds 500 parts by weight, the matching property between the heat-sensitive recording layer and the thermal head may decrease.

The heat-sensitive recording layer may further contain, if necessary, other components in addition to the sensitizer as long as the effects of the present invention are not impaired. Examples thereof include stearic acid and stearic acid. In addition to a metal salt co-dispersion, a zinc compound, a heat-fusible compound, a pigment, a metal soap, a wax, a hindered phenol compound, a water-proofing agent, and the like, a known additive usable in the heat-sensitive recording layer (for example, polyurea) Oil-absorbing substances such as fillers, fatty acids, antistatic agents, ultraviolet absorbers, defoamers, conductive agents, fluorescent dyes, and surfactants).

The addition of the zinc compound to the heat-sensitive recording layer is preferred from the viewpoint of improving image storability. Examples of the zinc compound include zinc oxide, zinc hydroxide,
Zinc carbonate, zinc phosphate, zinc silicate and the like can be mentioned, among which zinc oxide is preferable. In the heat-sensitive recording layer,
Usually, the content of the zinc compound is preferably 10 to 400% by weight based on the weight of the electron-accepting compound.
~ 300% by weight is more preferred. If the content is less than 10% by weight, the effect of improving the image storability may not be sufficient. In some cases, the dispersion stability may decrease.

The addition of the heat-fusible compound to the heat-sensitive recording layer is preferable in that the thermal response can be improved.
Examples of the heat-fusible compound include 1,2-diphenoxyethane and 1,2-bis (3-methylphenoxy).
Ethane, 1,4-diphenoxybutane, 1,2-bis (4-methoxyphenoxy) propane, 1,3-bis (4-methoxyphenoxy) propane, 1- (3-ethylphenoxy) -2-phenoxyethane, Examples thereof include 1,4-bis (phenoxymethyl) benzene and 1,4-bis (3-methylphenoxymethyl) benzene. These may be used alone or in combination of two or more.

In addition to these, the following heat-fusible compounds may be used in combination. Specific examples thereof include aromatic ethers, thioethers, esters, aliphatic amides, and ureides. No.58-57989, 5
8-87094, 61-58789, 62-1
No. 09681, No. 62-132677, No. 63-15
Nos. 1478 and 63-235961.

The content of the heat-fusible compound in the heat-sensitive recording layer was 2 parts by weight based on 100 parts by weight of the electron-accepting compound.
The amount is preferably from 0 to 300 parts by weight, more preferably from 40 to 150 parts by weight.

It is preferable that the pigment is added to the heat-sensitive recording layer in that the recording head can be prevented from being stained during recording. The pigment is not particularly limited, for example, kaolin, calcined kaolin, talc, fluorite, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, Calcined stone, silica, magnesium carbonate, titanium oxide, alumina, barium carbonate,
Examples include barium sulfate, mica, microballoons, urea-formalin filler, polyester particles, cellulose filler and the like.

It is preferable that the metal soap is added to the heat-sensitive recording layer, because the releasability of the recording head from the recording head can be improved during recording. Examples of the metal soap include higher fatty acid polyvalent metal salts, specifically, zinc stearate, aluminum stearate,
Examples include calcium stearate and zinc oleate.

It is preferable that the wax is added to the heat-sensitive recording layer, for example, since the head matching property with respect to facsimile can be improved. As the wax, a wax having a melting point of 40 to 120 ° C. is preferable,
For example, paraffin wax, polyethylene wax,
Carnauba wax, microcrystalline wax, canderia wax, montan wax, fatty acid amide wax and the like are preferred. Paraffin wax having a melting point of 50 to 100 ° C., montan wax, methylol stearamide, and the like are more preferable. The content of the wax in the heat-sensitive recording layer is preferably 5 to 200 parts by weight, and more preferably 20 to 150 parts by weight based on 100 parts by weight of the electron-donating dye precursor.
Parts by weight are more preferred.

The hindered phenol compound preferably includes, for example, a phenol derivative in which at least one of the 2-position and the 6-position is substituted with a branched alkyl group.

Examples of the ultraviolet absorber include cinnamic acid derivatives, benzophenone derivatives, benzotriazole phenol derivatives and the like. Specifically, α-cyano-β-phenyl cinnamate butyl, o-benzotriazole phenol, o-benzotriazole-p-chlorophenol, o-benzotriazole-2,4-di-t-
Butylphenol, o-benzotriazolyl-2,4-
Di-t-octylphenol and the like.

Examples of the waterproofing agent include water-soluble initial condensates such as N-methylol urea, N-methylol melamine, and urea-formalin; dialdehyde compounds such as glyoxal and glutaraldehyde; and inorganic cross-linking such as boric acid and borax. And heat-treated blends of polyacrylic acid, methyl vinyl ether-maleic acid copolymer, isobutylene-maleic anhydride copolymer, and the like.

The heat-sensitive recording layer can be formed by applying a coating solution containing each component on a support. Specific methods and means will be described later. The layer thickness of the heat-sensitive recording layer is preferably 4 to 15 μm, and 6 to 10 μm.
m is more preferred.

[Support] The support for the heat-sensitive recording material of the present invention is not particularly limited. For example, high quality paper (acid paper, neutral paper), recycled paper, medium paper, coated paper, art paper ,
Paper with magnetic layer, support, resin laminated paper, synthetic fiber paper, synthetic resin film, white PET, transparent PET, colored PET, synthetic resin film with magnetic layer, coated paper with resin or pigment applied to paper, synthetic Paper etc. are mentioned. The surface of the support is preferably smooth in terms of dot reproducibility, and the smoothness (smoothness specified by JIS-8119) is preferably 500 seconds or more.
More than 00 seconds is more preferable.

When the support has a base color as described above, a commercially available support having a hue different from the color hue of the heat-sensitive recording layer may be used. May be used. The method of imparting a base color to the colorless support is not particularly limited, but it is preferable to use a colored dye or a colored pigment used to impart a base color to the heat-sensitive recording layer described above.
Further, the content of the colored dye and the colored pigment in the support can be appropriately selected according to the purpose,
In general, these colored dyes and pigments have a dry adhesion amount of 0.001 to 1 g per m ² of the support.

[Protective Layer] The heat-sensitive recording materials of the first and third inventions may have a protective layer as the other layer on the heat-sensitive recording layer. On the other hand, the heat-sensitive recording material of the second invention has a protective layer on the heat-sensitive recording layer.

When the protective layer has a base color as described above, the method of applying the base color to the protective layer is not particularly limited. It is preferable to use a colored dye or a colored pigment used for attaching a colorant. In addition, the content of the colored dye and the colored pigment in the protective layer can be appropriately selected according to the purpose, but generally, these colored dyes and the colored pigment are dried when dried per 1 m ² of the support. Is 0.001 g to 1 g.

The protective layer may have a single-layer structure or a laminated structure. The protective layer is, for example, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, gelatins, gum arabic, casein, styrene -Maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, polystyrene sodium sulfonate, sodium alginate, etc. Water-soluble polymer and styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate emma It can be formed by using a water-insoluble polymer John such like.

The protective layer may contain the pigment, the metal soap, the wax, the waterproofing agent, etc. for the purpose of improving the matching property with a recording head such as a thermal head. When the protective layer is coated on the heat-sensitive recording layer, a surfactant may be contained for the purpose of obtaining a uniform protective layer. Preferable examples of the surfactant include sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, and the like. Specifically, di- (n
Preferred are sodium salts, ammonium salts and the like, such as -hexyl) sulfosuccinic acid and di- (2-ethylhexyl) sulfosuccinic acid, and anionic surfactants are preferred.

[Undercoat Layer] The heat-sensitive recording materials of the first and second inventions may have an undercoat layer as the other layer between the support and the heat-sensitive recording layer. On the other hand, the heat-sensitive recording material of the third invention has an undercoat layer between the support and the heat-sensitive recording layer.

When the undercoat layer has a base color as described above, a method of adding a base color to the undercoat layer is as follows.
Although it is not particularly limited, it is preferable to use a colored dye or a pigment used for coloring the heat-sensitive recording layer as described above. Further, the content of the colored dye and the colored pigment in the undercoat layer can be appropriately selected according to the purpose, but generally, these colored dyes and the colored pigment are dried per 1 m ² of the support. Is 0.001 g to 1 g.

When an undercoat layer is provided on the support, an undercoat layer containing a pigment as a main component is preferable. As the pigment, all general organic or inorganic pigments can be used. In particular, those having an oil absorption of 40 cc / 100 g or more specified by JIS-K5101 are preferable, and specifically, calcium carbonate, barium sulfate, Titanium oxide,
Examples include talc, wax stone, kaolin, calcined kaolin, aluminum hydroxide, amorphous silica, urea formalin resin powder, polyethylene resin powder and the like. When these pigments are applied to a support, the amount of the pigment is preferably ² g / m ² or more, more preferably 4 g / m ² or more.

The binder used in the undercoat layer includes a water-soluble polymer and a water-soluble binder, and these may be used alone or in combination of two or more. Water-soluble polymers include methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, starches, gelatin, gum arabic, casein,
Styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol, polyacrylamide, and the like.

The water-soluble binder is generally a synthetic rubber latex or a synthetic resin emulsion, such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. . The amount of the binder used is 3 to 100% by weight, preferably 5 to 100% by weight based on the pigment added to the undercoat layer.
50% by weight. The undercoat layer may contain a wax, a decoloring inhibitor, a surfactant and the like.

[Other Layers] The heat-sensitive recording material of the present invention comprises:
A back coat layer may be provided on the back surface of the support (the surface of the support on which the heat-sensitive recording layer is not formed). It is preferable to provide a back coat layer because the curl balance of the support can be corrected and the chemical resistance is improved. The back coat layer can be formed by applying a coating solution having the same composition as that of the protective layer on the back surface of the support. Also, instead of providing the back coat layer, an adhesive is applied to the back surface of the support (the surface of the support on the side on which the heat-sensitive recording layer is not provided), and further combined with release paper to form a label. You may.

<Production method of heat-sensitive recording material> The heat-sensitive recording material of the present invention has at least a heat-sensitive recording layer on a support, but the production method is not particularly limited. The coating solution for the heat-sensitive recording layer prepared as follows can be prepared by coating on a support and drying. The coating solution for the heat-sensitive recording layer includes at least one kind of microcapsules containing the electron-donating dye precursor in the form of solid fine particles, the electron-accepting compound in the form of solid fine particles or emulsified and dispersed, and the electron-donating dye precursor. It contains other components such as a sensitizer if necessary.

The method for preparing the coating solution is not particularly limited, and can be appropriately selected according to the purpose. For example, the coating solution can be prepared as follows. First, in a dispersion medium containing a water-soluble polymer such as polyvinyl alcohol, an electron-donating dye precursor in the form of solid fine particles capable of forming a color at the lowest temperature is added, and pulverized to obtain an average particle size of 1.0 μm.
Solid fine particle dispersion (i) of the following electron-donating dye precursor
Is prepared. Similarly, an electron-accepting compound represented by the general formula (I) is added to a dispersion medium containing a water-soluble polymer such as polyvinyl alcohol, and pulverization is performed. A solid fine particle dispersion (ii) of an acceptor compound is prepared. In preparing the dispersions (i) and (ii), the crystal of the electron-donating dye precursor and the crystal of the electron-accepting compound are each pulverized into fine particles during the pulverization treatment,
A water-soluble polymer is adsorbed on the surface of the fine particles.

Next, the dispersions (i) and (ii) are mixed. In the dispersions (i) and (ii), since the electron-donating dye precursor and the electron-accepting compound are protected by the water-soluble polymer compound adsorption layer, no color-forming reaction occurs even when they are mixed. One or more kinds of separately prepared microcapsule dispersions containing an electron-donating dye precursor are added to the mixture, and the mixture is homogenized to prepare the coating solution.
Here, in the case where other components such as a sensitizer are contained, it may be added at the time of preparing each dispersion, or simultaneously with the addition of the electron-donating dye precursor-encapsulated microcapsule dispersion in the mixture. Good. A method for preparing the electron-donating dye precursor-encapsulated microcapsule dispersion will be described later.

When other components such as a sensitizer are contained, a dispersion (iii) in which other components are dispersed and dissolved in a separately prepared dispersion medium may be prepared in advance. In this case, after adding and mixing the dispersions (i) and (ii) to the dispersion (iii), one or more separately prepared microcapsule dispersions containing an electron-donating dye precursor are added. Can be prepared by homogenization.

The dispersion medium is usually 0.5 to 10
An aqueous solution of a water-soluble polymer of about weight% is suitably used.
If the concentration of the aqueous solution of the water-soluble polymer is too low, the viscosity of the dispersion medium may decrease, and the particles dispersed in a solid state may easily precipitate. On the other hand, if the temperature is too high, the viscosity of the coating solution for the heat-sensitive recording layer may increase, and the coating properties may not be evenly applied.

Examples of the water-soluble polymer used as a dispersion medium for preparing the dispersions (i) and (ii) (optionally dispersion (iii)) include, for example, polyvinyl alcohol, hydroxyethylcellulose, hydroxypropylcellulose, epichlorohydrin Modified polyamide, ethylene-
Maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic salicylic anhydride copolymer, polyacrylic acid, polyacrylamide, methylol-modified polyacrylamide, starch derivatives, casein, gelatin and the like, These water-soluble polymers are
It is used by dissolving it in an appropriate aqueous solvent. Among them, polyvinyl alcohol is preferred because it functions as a protective colloid and improves the dispersion stability of the electron-donating dye precursor of solid fine particles or the electron-accepting compound represented by the general formula (I).

In the preparation of the dispersions (i) to (iii), in order to disperse or dissolve the first electron-donating dye precursor or the electron-accepting compound in the dispersion medium, a known dispersion apparatus is used. For example, a ball mill, a sand mill, a horizontal sand mill, an attritor, a colloidal mill and the like can be used.

Next, a method for preparing the electron-donating dye precursor-encapsulated microcapsule dispersion will be described. In the heat-sensitive recording layer of the heat-sensitive recording material of the present invention, in addition to the first electron-donating dye precursor used in the form of solid fine particles as described above, at least one kind of electron-donating dye precursor (second An electron-donating dye precursor) is encapsulated in a microcapsule and used. The method for microencapsulation can be appropriately selected from conventionally known methods. As a method of microencapsulation, for example, US Pat.
Nos. 457 and 280,458, which use coacervation of a hydrophilic wall forming material, U.S. Pat. No. 3,287,154, British Patent No. 990443, JP-B-38-19574, JP-B-42-446, and JP-A-42-446. −77
No. 3,418,250.
No. 3,660,304, a method using polymer deposition, a method using an isocyanate polyol wall material described in U.S. Pat. No. 3,796,669, and a method described in U.S. Pat.
511, a method using an isocyanate wall material,
Urea-formaldehyde system described in U.S. Patent Nos. 4,001,140, 4,087,376 and 4,089,802;
Urea-formaldehyde-resorcinol-based wall-forming material, U.S. Pat.
No. 68, JP-A-51-9079, in-situ method by polymerization of monomers, British Patent No. 952807.
No. 965074, the electrolytic dispersion cooling method described in US Pat. No. 3,111,407, the spray drying method described in British Patent No. 930422, Japanese Patent Publication No. 7-73069,
Examples thereof include the methods described in JP-A-4-101885 and JP-A-9-263057.

The method of microencapsulation is not limited to these, but in the heat-sensitive recording material of the present invention, in particular, the second electron-donating dye precursor may be used in a hydrophobic form which serves as a core of the capsule. An oil phase prepared by dissolving or dispersing in an organic solvent is mixed with an aqueous phase in which a water-soluble polymer is dissolved, emulsified and dispersed by means of a homogenizer or the like, and then heated to form a polymer forming reaction at the oil droplet interface. It is preferable to employ an interfacial polymerization method for causing microcapsule walls of a polymer substance to occur. The interfacial polymerization method,
Capsules having a uniform particle size can be formed in a short time.

As for the microcapsules used in the present invention, at room temperature, the wall material of the microcapsules (hereinafter, sometimes simply referred to as “capsule wall”) is impermeable to substances, and the contact between substances inside and outside the capsules is prevented. The microcapsules are preferably microcapsules that, when hindered and heated to a certain temperature or higher, make the capsule wall material permeable and allow material inside and outside the capsule to contact. This property is
By appropriately selecting the material of the capsule wall, the capsule core substance (the substance contained in the capsule), the additives and the like, the physical properties of the capsule can be freely controlled.

In the case of the heat-sensitive recording material of the present invention, when the heat-sensitive recording layer contains two or more kinds of microcapsules containing different electron-donating dye precursors, the material used for the capsule wall of each microcapsule is selected. Then, microcapsules having different temperature ranges in which the capsule wall changes from the material non-permeability to the material permeation are used. Changing the structure of the polymer used as the material of the capsule wall,
And / or the presence of a wall material that undergoes a glass transition outside the capsule allows the production of microcapsules having different glass transition points on the capsule wall. When two or more kinds of macrocapsules are used, the wall material of each microcapsule has a difference in glass transition point between the capsules of 20 ° C.
It is preferable that the selection be made as described above. Further, from the viewpoint of increasing the sensitivity of the thermosensitive recording material, the glass transition temperature (glass transition point) of each microcapsule is usually 1
The temperature is preferably from 00 to 200 ° C, more preferably from 120 to 160 ° C. The glass transition temperature (glass transition point) of the capsule wall means the peak temperature of tan δ measured by a known viscoelasticity measuring instrument such as Vibron, and is obtained by dividing the dynamic loss modulus by the storage property. is there.

As the material (wall material) of the capsule wall,
For example, polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer and the like, among which polyurethane, polyurea, polyamide, polyester, polycarbonate Are preferable, and polyurethane and polyurea are more preferable. The material of the capsule wall is added inside the oil droplet and / or outside the oil droplet. The polymer substances may be used in combination of two or more kinds.

For example, when polyurethane is used as a capsule wall material, a polyvalent isocyanate and a second substance (for example, polyol or polyamine) which reacts with the polyisocyanate to form a capsule wall are mixed with a water-soluble polymer aqueous solution (aqueous phase) or After mixing in an oily medium (oil phase) to be encapsulated and emulsifying and dispersing in water, the mixture is heated to cause a polymer formation reaction at the oil droplet interface to form microcapsule walls. Examples of the polyvalent isocyanate and the polyol and polyamine to be reacted therewith include US Pat. No. 3,281,383.
Nos. 3,737,695, 3,973,268, JP-B-48-40347, JP-A-49-24159, and JP-A-Showa 4
JP-A-8-80191 and JP-A-48-84086 can be used.

When forming microcapsules, the encapsulated electron-donating dye precursor may be present in the capsules in a solution state or a solid state. When encapsulated in a solution state, the capsule may be encapsulated in a state where the electron-donating dye precursor is dissolved in an organic solvent.

In general, the organic solvent can be appropriately selected from solvents having a high boiling point, and examples thereof include phosphoric acid esters, phthalic acid esters, acrylic acid esters, methacrylic acid esters, other carboxylic acid esters, and fatty acid amides. , Alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diallylethane, solid compounds at room temperature, oligomer oils,
Polymer oil and the like. More specifically,
Nos. 9-178451 to 59-178455, 59-
No. 178457, No. 60-242094, No. 63-8
5633, JP-A-6-194825 and 7-133
Organic solvents described in JP-A Nos. 10-7-13311, 9-106039 and Japanese Patent Application No. 62-75409 are exemplified. The amount of the organic solvent used,
1 to 500 parts by weight per 100 parts by weight of the electron donating dye precursor
Parts by weight are preferred. Further, at the time of encapsulation, a so-called oilless capsule may be used without using the organic solvent.

When the solubility of the electron-donating dye precursor to be encapsulated in the microcapsules in the organic solvent is low, a low-boiling solvent having high solubility may be used as an auxiliary solvent. . On the other hand, the low boiling point solvent can be used without using the organic solvent. Examples of the low boiling point solvent include ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like.

As the aqueous phase in which the oil phase is emulsified and dispersed, an aqueous solution in which a water-soluble polymer is dissolved is used. After the oil phase is introduced into the aqueous phase, emulsification and dispersion are performed by means such as a homogenizer.The water-soluble polymer acts as a protective colloid that can make the dispersion uniform and easy, and stabilizes the emulsified aqueous solution. Also acts as a dispersion medium to be converted. Here, a surfactant can be added to at least one of the oil phase and the aqueous phase in order to perform the emulsification and dispersion more uniformly and to obtain a more stable dispersion.

The water-soluble polymer to be contained as the protective colloid is the same as the water-soluble polymer contained in the dispersion medium used for preparing the dispersion (i) and the like, and examples thereof include polyvinylpyrrolidone. Can be Since the microcapsule dispersion is mixed with the dispersion (i) or the like containing an electron-donating dye precursor, an electron-accepting compound, and the like, the water-soluble polymer is used in order to improve the compatibility between the two. It is preferable to use the same one as used for the dispersion liquid (i) and the like.

The surfactant can be appropriately selected from known surfactants for emulsification. For example, anionic or nonionic surfactants can be used as described above to interact with the protective colloid. However, those which do not cause precipitation or aggregation can be appropriately selected and used. Specifically, sodium alkylbenzene sulfonate, sodium alkyl sulfate, dioctyl sulfosuccinate sodium salt,
Polyalkylene glycol (for example, polyoxyethylene nonylphenyl ether) and the like can be mentioned. The addition amount of the surfactant is 0.1 to 5 with respect to the weight of the oil phase.
% Is preferable, and 0.5 to 2% is more preferable.

The emulsification and dispersion may be performed by means used for emulsification of fine particles such as high-speed stirring and ultrasonic dispersion, for example, a homogenizer,
It can be easily carried out by a known emulsifying apparatus such as Menton-Gawley, ultrasonic disperser, dissolver, Keddy mill and the like.

After the emulsification, the emulsion is heated to 30 to 70 ° C. in order to promote the capsule wall forming reaction. During the reaction, in order to prevent aggregation of the capsules, it is necessary to reduce the probability of collision between the capsules by adding water, or to perform sufficient stirring. As for the end point of the capsule wall forming reaction, generation of carbon dioxide gas is observed with the progress of the polymerization reaction, and the end of the generation can be regarded as an approximate end point. Usually, microcapsules containing the electron-donating dye precursor can be obtained by performing the reaction for several hours.

In the present invention, the average particle size of the microcapsules is preferably 20 μm or less, and more preferably 5 μm or less from the viewpoint of obtaining high resolution and improving the transparency of the thermosensitive recording layer. On the other hand, if the microcapsule diameter is too small, the surface area with respect to a certain solid content becomes large and a large amount of wall material is required. Therefore, the average particle diameter is preferably 0.1 μm or more.

The heat-sensitive recording material of the present invention can be prepared by applying the above-mentioned coating solution for the heat-sensitive recording layer on a support and drying it. Examples of the coating method include an air knife coater, a blade coater, a bar coater, a gravure coater, a curtain coater, and a wire bar.

The heat-sensitive recording material of the present invention can record an image by applying heat imagewise by a heating means such as a thermal head. The heating means is preferably controlled so that the amount of heat to be supplied can be increased or decreased according to the hue of the image to be recorded.

[0110]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Here, the “average particle size” means “volume average particle size”. (Example 1) [Preparation of microcapsule solution A containing black coloring dye precursor]
6 parts by weight of 2-anilino-3-methyl-6-N-ethyl-N-sec-butylaminofluoran (manufactured by Nippon Soda Co .; trade name: PSD184) as an electron-donating dye precursor;
12 parts by weight of Takenate D110N (manufactured by Takeda Pharmaceutical) as a wall material, 12 parts by weight of KMC113 (manufactured by Kureha Chemical Co., Ltd.),
And 10 parts by weight of ethyl acetate. This solution was mixed with 112 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name: PVA-217C: saponification degree: 88%), and mixed with an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.).
Emulsified at 000 rpm for 10 minutes, further added 60 parts by weight of water and 0.5 parts by weight of tetraethylenepentamine,
For 3 hours to prepare a microcapsule solution A containing a black color dye precursor having a capsule size of 1.1 μm.

[Preparation of Red Coloring Dye Precursor Dispersion B] As an electron donating dye precursor, 14 parts by weight of 3-dimethylamino-7-chlorofluorane and 3-dimethylamino-6
6 parts by weight of 8-dimethylfluorane was partially saponified polyvinyl alcohol having a concentration of 5% (manufactured by Kuraray Co., Ltd .; trade name PVA-2).
05: 88% saponification degree) An aqueous solution was mixed with 80 parts by weight of an aqueous solution and pulverized using a sand mill to prepare a red-coloring dye precursor dispersion B having an average particle size of 0.60 μm.

[Preparation of Sensitizer Dispersion] 20 parts by weight of 1-benzyloxynaphthalene was mixed with 70 parts by weight of a 5% aqueous solution of partially saponified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name: PVA-205). To obtain a sensitizer dispersion having an average particle size of 0.60 μm.

[Preparation of Electron-Accepting Compound Dispersion] 4-[[4- (1-methylethoxy)
20 parts by weight of phenyl] sulfonyl] phenol (manufactured by Nippon Soda Co .; trade name D-8) are mixed with 70 parts by weight of a 5% aqueous solution of partially saponified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name PVA-205), and the mixture is mixed with a sand mill. To prepare an electron-accepting compound dispersion having an average particle diameter of 0.60 μm.

[Preparation of pigment dispersion] Calcium carbonate 40
Parts by weight, 60 parts by weight of water and 0.4 parts by weight of a 10% aqueous solution of sodium hexametaphosphate were pulverized using a sand mill to prepare a pigment dispersion having an average particle diameter of 0.60 μm.

[Preparation of Coating Solution for Thermosensitive Recording Layer] 5 parts by weight of the microcapsule solution A containing the black color dye precursor, 5 parts by weight of the red color dye precursor dispersion B, 5 parts by weight of the sensitizer dispersion,
5 parts by weight of an electron-accepting compound dispersion, 5 parts by weight of a pigment dispersion, and a blue colored dye for coloring the base (TB-590 NavyBlue R, manufactured by Dainichi Seika).
Hydrin Z-7 (trade name, manufactured by Chukyo Yushi Co., Ltd.) 0.8 parts by weight, Hydrin D337 (trade name, manufactured by Chukyo Yushi Co., Ltd.) 0.8 parts by weight, 2% by weight, 2%
Was mixed with 1.0 part by weight of an aqueous solution of sodium (2-ethylhexyl) sulfosuccinate and 15 parts by weight of water to prepare a coating solution for the heat-sensitive recording layer.

[Preparation of heat-sensitive recording paper] The above-mentioned heat-sensitive recording layer coating solution was applied to the surface of a paper support using a wire bar so that the weight of the heat-sensitive recording layer after drying was 8 g / m ^2.
After drying in oven at ℃, smoothness 300 seconds (Beck method)
Then, a calendering process was performed to produce a thermosensitive recording paper.

(Example 2) [Preparation of microcapsule liquid C containing black color dye precursor]
Microcapsule liquid A containing black color dye precursor of Example 1
Is prepared using 3-di (n-butylamino) -6-methyl-7-anilinofluoran (manufactured by Nippon Soda Co., Ltd.) as an electron donating dye precursor, and Takenate D110N (manufactured by Takeda Pharmaceutical Co., Ltd.) as a wall material. 10 parts by weight and Barnock D
750 (manufactured by Dainippon Ink and Chemicals Co., Ltd.), except that the emulsification conditions were changed to 8000 rpm, and a microcapsule solution C containing a black color dye precursor having a capsule size of 0.67 μm was prepared in the same manner as in Example 1. did.

[Preparation of Blue Dye Precursor Dispersion D] 3- (4-diethylamino-2) was used as an electron-donating dye precursor.
20 parts by weight of -ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide was partially saponified polyvinyl alcohol having a concentration of 5% (manufactured by Kuraray Co., Ltd .; trade name PVA-205: degree of saponification). 88%) aqueous solution 80
The resulting mixture was mixed with parts by weight and pulverized using a sand mill to prepare a blue-colored dye precursor dispersion D having an average particle size of 0.55 μm.

[Preparation of Sensitizer Dispersion] The procedure of Example 1 was repeated except that 1-benzyloxynaphthalene was replaced by 1,2-diphenoxymethylbenzene in the preparation of the sensitizer dispersion of Example 1. A sensitizer dispersion was prepared by the method described above.

[Preparation of Electron-Accepting Compound Dispersion] In the preparation of the electron-accepting compound dispersion of Example 1, 4-
[Example] Except that [[4- (1-methylethoxy) phenyl] sulfonyl] phenol was changed to 4-hydroxyphenyl-4′-benzyloxyphenylsulfone (manufactured by Nikka Chemical Co., Ltd .; trade name: BPS-BN). In the same manner as in Example 1, an electron accepting compound dispersion having an average particle size of 0.52 μm was prepared.

[Preparation of Coating Solution for Thermosensitive Recording Layer] 5 parts by weight of the above microcapsule solution C containing a black coloring dye precursor, 5 parts by weight of a blue coloring dye precursor dispersion D, 5 parts by weight of a sensitizer dispersion,
5 parts by weight of an electron-accepting compound dispersion, 5 parts by weight of a pigment dispersion similar to that of Example 1, 0.8 parts by weight of hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.) having a concentration of 31%, and 31% concentration Hydrin D337 (trade name, manufactured by Chukyo Yushi Co., Ltd.) 0.8 parts by weight, 2 parts by weight of a 2% (2-ethylhexyl) sodium sulfosuccinate aqueous solution 1.0 part by weight, and 15 parts by weight of water were mixed to prepare a coating solution for the heat-sensitive recording layer. Prepared.

[Preparation of Coating Solution for Protective Layer] The following components were dispersed and mixed in a sand mill (manufactured by Seamul Enterprise).
A protective layer coating solution was prepared. Polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; PVA124) 2 parts by weight Aluminum hydroxide (manufactured by Showa Denko; Hijilite H42S) 3 parts by weight Red dye for coloring the underlayer 0.01 parts by weight (manufactured by Sumitomo Chemical Co., Ltd .; trade name Japanol Fast Red T) zinc stearate emulsion 0.2 parts by weight (manufactured by Chukyo Yushi Co., Ltd .; Hydrin F930) ) Surfactant 0.1 part by weight (Dainippon Ink Co., Ltd .; Megafac F120)

[Preparation of Thermosensitive Recording Paper] The weight of each of the dried thermosensitive recording layer and the protective layer on the paper support was 8 g.
/ M ² and 0.5 g / m ² , the above-mentioned coating solution for the thermosensitive recording layer and the coating solution for the protective layer were sequentially applied using a wire bar, dried in an oven at 60 ° C., and then smoothed for 300 seconds ( (Beck method) to produce a heat-sensitive recording paper.

Example 3 Preparation of Microcapsule Solution E Containing Cyan Coloring Dye Precursor In the preparation of microcapsule solution A containing a black coloring dye precursor in Example 1, 3-electron-donating dye precursor was used.
(1-methyl-2-methylindol-3-yl) -3
-(4-diethylamino-2-methylphenyl) -4-
Using azaphthalide, Takenate D110N as wall material
(Takeda Pharmaceutical) 10 parts by weight and Millionate MR400
Example 1 except that 2 parts by weight (manufactured by Nippon Polyurethane Industry Co., Ltd.) were used and emulsification conditions were changed to 4500 rpm for 15 minutes.
A microcapsule solution E containing a cyan coloring dye precursor having a capsule size of 1.43 μm was prepared in the same manner as in the above.

[Preparation of magenta coloring dye precursor dispersion liquid F] 3,3'-bis (1-
20 parts by weight of n-octyl-2-methylindol-3-yl) phthalide was added to a 5% concentration partially saponified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name: PVA-205: saponification degree 8).
8%) The resulting mixture was mixed with 80 parts by weight of an aqueous solution and pulverized using a sand mill to prepare a magenta coloring dye precursor dispersion F having an average particle size of 0.55 μm.

[Preparation of Electron-Accepting Compound Dispersion] As an electron-accepting compound, 20 parts by weight of zinc 4-β-phenoxyethoxysalicylate was added to a 5% strength aqueous solution of partially saponified polyvinyl alcohol (Kuraray; PVA-205). 7
The mixture was mixed with 0 parts by weight and pulverized with a sand mill to prepare an electron accepting compound dispersion.

[Preparation of coating solution for thermosensitive recording layer] 5 parts by weight of microcapsule solution E containing the cyan coloring dye precursor, 5 parts by weight of magenta coloring dye precursor dispersion F, 5 parts by weight of electron accepting compound dispersion, Examples Sensitizer dispersion liquid 5 similar to 1
5 parts by weight of the same pigment dispersion as in Example 1, concentration 3
1% hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.)
8 parts by weight, 0.8% by weight of hydrin D337 (trade name, manufactured by Chukyo Yushi Co., Ltd.) having a concentration of 31%, 2 parts by weight of an aqueous solution of sodium (2-ethylhexyl) sulfosuccinate 1.0% by weight,
And 15 parts by weight of water were mixed to prepare a coating solution for the heat-sensitive recording layer.

[Preparation of Thermosensitive Recording Paper] The above thermosensitive recording layer coating solution was applied on a yellow paper support surface using a wire bar so that the weight of the dried thermosensitive recording layer was 8 g / m ² , After drying in an oven at a temperature of ℃, it was subjected to a calendering treatment so as to have a smoothness of 300 seconds (Beck method), thereby producing a thermosensitive recording paper.

(Example 4) [Preparation of microcapsule solution G containing magenta coloring dye precursor] 3,3'-bis (1) was used as an electron donating dye precursor.
-N-octyl-2-methylindol-3-yl) phthalide (Ciba-Geigy; trade name Perga)
6 parts by weight of Script Red I-6B) and 12 parts by weight of Takenate D110N (manufactured by Takeda Chemical) as a wall material were dissolved in 12 parts by weight of KMC113 (manufactured by Kureha Chemical Co., Ltd.) and 10 parts by weight of ethyl acetate. This solution was treated with a 5% by weight aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co .; trade name PV
A-217C: saponification degree 88%)
6000 with Ace Homogenizer (manufactured by Nippon Seiki)
The emulsion was emulsified at 10 rpm for 10 minutes, further added with 60 parts by weight of water and 0.5 parts by weight of tetraethylenepentamine, and reacted at 50 ° C. for 3 hours to obtain a microcapsule solution G containing a magenta coloring dye precursor having a capsule size of 1.15 μm. Was prepared.

[Preparation of Black Capsule Dye Precursor-Containing Microcapsule Solution H] As an electron-donating dye precursor, 2-anilino-3-methyl-6-N-ethyl-N-sec-butylaminofluoran (Nippon Soda Co., Ltd.) Product name: PSD184)
6 parts by weight, 4 parts by weight of Takenate D110N (manufactured by Takeda Pharmaceutical Co., Ltd.) and 8 parts by weight of Barnock D750 (manufactured by Dainippon Ink) as wall materials, and
It was dissolved in 2 parts by weight and 10 parts by weight of ethyl acetate. This solution is treated with a 5% by weight aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co .; trade name: PVA-217C: saponification degree: 88%) 112
Parts by weight, emulsified at 6000 rpm for 8 minutes with an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.),
Parts by weight and 0.5 parts by weight of tetraethylenepentamine were added and reacted at 65 ° C. for 3 hours to obtain a capsule size of 1.22 parts.
A microcapsule liquid H containing a black coloring dye precursor having a thickness of μm was prepared.

[Preparation of Yellow Coloring Dye Precursor Dispersion I] 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2-quinolyl) ethylene (Yamada Chemical Co., Ltd.) as an electron donating dye precursor 20 parts by weight of a product (trade name: Y721) was mixed with 80 parts by weight of a 5% aqueous solution of partially saponified polyvinyl alcohol (manufactured by Kuraray; trade name: PVA-205: saponification degree: 88%), and pulverized using a sand mill. Yellow coloring dye precursor dispersion liquid I having an average particle size of 0.57 μm
Was prepared.

[Preparation of Electron-Accepting Compound Dispersion] As an electron-accepting compound, 20 parts by weight of bis (3-allyl-4-hydroxyphenyl) sulfone was added to a 5% concentration aqueous solution of partially saponified polyvinyl alcohol (manufactured by Kuraray Co .; trade name). PVA
-205) 70 parts by weight and pulverized using a sand mill to prepare an electron accepting compound dispersion.

[Preparation of coating solution for heat-sensitive recording layer] 4 parts by weight of the above-mentioned microcapsule solution G containing the magenta coloring dye precursor,
Black coloring dye precursor-containing microcapsule solution H4 parts by weight,
4 parts by weight of yellow color dye precursor dispersion liquid, 5 parts by weight of electron accepting compound dispersion liquid, 5 parts by weight of sensitizer dispersion liquid as in Example 1, 5 parts by weight of pigment dispersion liquid as in Example 1, 0.01 parts by weight of a green organic pigment for coloring the base (manufactured by Dainichi Seika; trade name: TB-516), 0.8 parts by weight of hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.) having a concentration of 31% 0.8% by weight of Hydrin D337 (trade name of Chukyo Yushi Co., Ltd.) having a concentration of 31%, 1.0% by weight of a 2% aqueous solution of sodium (2-ethylhexyl) sulfosuccinate, and 15 parts by weight of water
The heat-sensitive recording layer coating solution was prepared by mixing parts by weight.

[Preparation of heat-sensitive recording paper] The above-mentioned heat-sensitive recording layer coating solution was applied on a paper support surface using a wire bar so that the weight of the heat-sensitive recording layer after drying was 8 g / m ^2.
After drying in oven at ℃, smoothness 300 seconds (Beck method)
Then, a calendering process was performed to produce a thermosensitive recording paper.

(Example 5) [Preparation of undercoat layer coating solution] The following components were mixed to prepare an undercoat layer coating solution. Calcined clay (manufactured by Engelhard Co .; trade name: Ansilex) 10 parts by weight polyvinyl alcohol 10 parts by weight (manufactured by Kuraray; trade name: PVA) -205: 88% saponification degree) Yellow organic pigment for coloring the underlayer 0.05 parts by weight (manufactured by Dainichi Seika; trade name: TB-117)

[0136]

[Preparation of Black Capsule Dye Precursor-Containing Microcapsule Solution J] 3-Di (n-
6 parts by weight of butylamino) -6-methyl-7-anilinofluoran, 8 parts by weight of Takenate D110N (manufactured by Takeda Pharmaceutical Co., Ltd.) and 4 parts by weight of Millionate MR400 (manufactured by Nippon Polyurethane Industry Co., Ltd.) as a wall material were added to KMC113 ( (Kureha Chemical Co., Ltd.) and 10 parts by weight of ethyl acetate. This solution was treated with a 5% by weight aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name PVA-217C: saponification degree 8).
8%) and emulsified at 7000 rpm for 8 minutes with an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.), and further 60 parts by weight of water and 0.1% of tetraethylenepentamine.
3 parts by weight and reacted at 65 ° C. for 3 hours to prepare a microcapsule solution J containing a black coloring dye precursor having a capsule size of 1.01 μm. [Preparation of magenta coloring dye precursor dispersion K] [Preparation of magenta coloring dye precursor dispersion F] of Example 3 except that 3-dimethylamino-7-chlorofluorane was used as the electron-donating dye precursor. In the same manner as in the above, magenta coloring dye precursor dispersion liquid K was prepared. .

[Preparation of Electron-Accepting Compound Dispersion] As an electron-accepting compound, 2,4-bis (phenylsulfonyl)
20 parts by weight of phenol is a 5% concentration partially saponified polyvinyl alcohol aqueous solution (manufactured by Kuraray Co., Ltd .; trade name PVA-20)
5) The mixture was mixed with 70 parts by weight and pulverized using a sand mill to prepare an electron-accepting compound dispersion.

[Preparation of coating solution for thermosensitive recording layer] 5 parts by weight of the above-mentioned microcapsule solution J containing the black coloring dye precursor, 5 parts by weight of the magenta coloring dye precursor dispersion K, 5 parts by weight of the electron accepting compound dispersion, Examples 5 parts by weight of the same sensitizer dispersion as in Example 1, 5 parts by weight of the same pigment dispersion as in Example 1, and a concentration of 31%
0.8 parts by weight of Hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.), 0.8 parts by weight of Hydrin D337 (trade name of Chukyo Yushi Co., Ltd.) with a concentration of 31%, and 2% of (2-ethylhexyl) sulfosuccinate 1.0 part by weight of an aqueous solution of sodium acid and 15 parts by weight of water were mixed to prepare a thermosensitive recording layer coating solution.

[Preparation of thermosensitive recording paper] The weight of the undercoat layer after drying and the weight of the thermosensitive recording layer were 7
g / m ^2, and so that 8 g / m ^2, the undercoat layer coating solution and a heat-sensitive recording layer coating solution are sequentially applied using a wire bar, dried in a 60 ° C. oven for smoothness 300 seconds ( (Beck method) to produce a heat-sensitive recording paper.

Example 6 Preparation of Microcapsule Solution L Containing Yellow Coloring Dye Precursor 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2- Quinolyl) ethylene (Y721, manufactured by Yamada Chemical Co., Ltd.)
6 parts by weight and 10 parts by weight of Takenate D110N (manufactured by Takeda Pharmaceutical Co., Ltd.) as a wall material were added to KMC113 (manufactured by Kureha Chemical Co., Ltd.).
It was dissolved in 12 parts by weight and 10 parts by weight of ethyl acetate. This solution was treated with a 5% by weight aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co .; trade name: PVA-217C: saponification degree: 88%).
2 parts by weight, emulsified with an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.) at 8000 rpm for 5 minutes, and further mixed with water 60
Parts by weight and 0.3 parts by weight of tetraethylenepentamine were added and reacted at 45 ° C. for 3 hours to obtain a capsule size of 1.25.
A microcapsule liquid L containing a yellow coloring dye precursor having a thickness of μm was prepared.

[Preparation of Black Capsule Dye Precursor-Containing Microcapsule Solution M] As the electron-donating dye precursor, 3-di (n-
6 parts by weight of butylamino) -6-methyl-7-anilinofluoran, 10 parts by weight of Takenate D110N (manufactured by Takeda Pharmaceutical) and 2 parts by weight of MDI-LK (manufactured by Mitsui Toatsu Chemicals) as wall materials, KMC113 (Kureha Chemical) 12
And 10 parts by weight of ethyl acetate. This solution was mixed with 112 parts by weight of a 5% by weight aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name PVA-217C: saponification degree: 88%), and an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.)
Emulsified at 6000 rpm for 10 minutes, and further added 60 parts by weight of water and 0.5 parts by weight of tetraethylenepentamine and reacted at 65 ° C. for 3 hours to obtain a capsule size of 1.16 μm.
m of microcapsule liquid M containing a black coloring dye precursor was prepared.

[Preparation of Cyan Color Dye Precursor Dispersion N]
3- (1-methyl-2-methylindol-3-yl) -3- (4-diethylamino-2-methylphenyl) -4-azaphthalide (manufactured by Yamada Chemical Co .; trade name: Blue220) as an electron-donating dye precursor 20 parts by weight with a concentration of 5
80 parts by weight of an aqueous solution of a partially saponified polyvinyl alcohol (manufactured by Kuraray Co .; trade name: PVA-205: saponification degree: 88%) and pulverized using a sand mill to prepare a cyan coloring dye precursor dispersion N.

[Preparation of Electron-Accepting Compound Dispersion] Bis (3-allyl-4-hydroxyphenyl) sulfone (20 parts by weight) as an electron-accepting compound was partially saponified in a 5% aqueous solution of polyvinyl alcohol (Kuraray Co., Ltd .; trade name). PVA
-205) 70 parts by weight and pulverized using a sand mill to prepare an electron accepting compound dispersion.

[Preparation of coating solution for heat-sensitive recording layer] The above microcapsule solution L4 containing parts by weight of the yellow coloring dye precursor was prepared by:
Black coloring dye precursor-containing microcapsule liquid M6 parts by weight,
Cyan color dye precursor dispersion liquid N4 parts by weight, electron-accepting compound dispersion liquid 5 parts by weight, sensitizer dispersion liquid 5 as in Example 1
5 parts by weight of the same pigment dispersion as in Example 1, concentration 3
1% hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.)
8 parts by weight, 0.8% by weight of hydrin D337 (trade name, manufactured by Chukyo Yushi Co., Ltd.) having a concentration of 31%, 2 parts by weight of an aqueous solution of sodium (2-ethylhexyl) sulfosuccinate 1.0% by weight,
And 15 parts by weight of water were mixed to prepare a coating solution for the heat-sensitive recording layer.

[Preparation of Thermosensitive Recording Paper] The above thermosensitive recording layer coating solution was applied on a pink paper support using a wire bar so that the weight of the thermosensitive recording layer after drying was 8 g / m ² , After drying in an oven at a temperature of ℃, it was subjected to a calendering treatment so as to have a smoothness of 300 seconds (Beck method), thereby producing a thermosensitive recording paper.

The thermal recording papers obtained in Examples 1 to 6 were evaluated as described below.

<Color development> The color density was measured by Kyocera Corporation.
Two color hues using a thermal printing tester (KST head)
Is 15mJ / mm^TwoAnd 50mJ / mm^TwoPrint d
15 mJ / m for energy and 3 colors hue
m^Two, 50mJ / mm^Two, And 85mJ / mm ^TwoPrint d
Printing with energy, and the color density
It was measured with a model RD-918 densitometer. In addition,
Visual observation of color separation and contrast between colored and background areas
evaluated. Table 1 shows the results.

[0149]

[Table 1]

From the results shown in Table 1, the heat-sensitive recording materials of the present invention of Examples 1 to 6 can obtain a clear image with high density and no color mixture, and have excellent color separation and contrast while having a simple structure. You can see that it is.

[0151]

According to the present invention, by applying a relatively low heat energy, a clear multicolor image with high density and no color mixture can be obtained, and it can be manufactured in a simple process at a low cost. It is possible to provide a multicolor-type heat-sensitive recording material having excellent color separation properties and contrast.

Claims (5)

[Claims] 1. A colorant having a different hue on a support.
At least one kind of electron-donating dye precursor, and a heat-sensitive recording material having a heat-sensitive recording layer containing an electron-accepting compound in the same layer, at least one of the two or more kinds of electron-donating dye precursors One is contained in the heat-sensitive recording layer in the form of solid fine particles,
At least one is contained in the heat-sensitive recording layer in a state encapsulated in microcapsules, and at least one of the support and the heat-sensitive recording layer is formed of the electron-donating dye precursor and the electron-accepting compound. A heat-sensitive recording material having a hue different from a hue that is developed by a reaction. 2. A colorant having a different hue on a support.
A heat-sensitive recording material having a heat-sensitive recording layer containing at least one kind of an electron-donating dye precursor and an electron-accepting compound in the same layer, and having a protective layer on the heat-sensitive recording layer; At least one of the above electron donating dye precursors is contained in the heat-sensitive recording layer in the form of solid fine particles,
At least one kind is contained in the heat-sensitive recording layer in a state encapsulated in microcapsules, and at least one of the support, the heat-sensitive recording layer and the protective layer comprises the electron-donating dye precursor and the electron-accepting compound. A heat-sensitive recording material having a hue different from the hue that develops color by the reaction with 3. An undercoat layer on a support, wherein two or more kinds of electron-donating dye precursors capable of developing different colors and an electron-accepting compound are contained in the same layer on the undercoat layer. A heat-sensitive recording material having a heat-sensitive recording layer, wherein at least one of the two or more electron-donating dye precursors is contained in the heat-sensitive recording layer in a solid fine particle state,
At least one kind is contained in the heat-sensitive recording layer in a state encapsulated in microcapsules, and at least one of the support, the undercoat layer and the heat-sensitive recording layer comprises the electron-donating dye precursor and the electron-accepting compound. A heat-sensitive recording material having a hue different from the hue that develops color by the reaction with 4. The method according to claim 1, wherein the volume-average particle diameter of the electron-donating dye precursor and the electron-accepting compound contained in the solid fine particle state is 1.0 μm or less. Thermal recording material. 5. The capsule wall of the microcapsule,
The heat-sensitive recording material according to any one of claims 1 to 4, comprising a polyurethane and / or a polyurea as a component.