JP2002002115A - Multicolor heat sensitive recording material and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor heat sensitive recording material, which has high sensitivity and favorable color separability in spite of a simple constitution thereof, excellent in high density and contrast and, on both the sides of which, multicolor images can be recorded. SOLUTION: This multicolor heat sensitive recording material has a heat sensitive recording layer including two or more kinds of electron donable dye precursors, which develop colors having hues different from one another, and an electron acceptable compound, which develops color in the electron donable dye precursor under heat, in one same layer. The electron donable dye precursor consists of one or more kinds of the electron donable dye precursors encapsulated in microcapsules different from one another and an at least one kind of the electron donable dye precursor which develops color having a hue different from that of the precursor encapsulated in the microcapsules and which is in finely divided solid particle state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor thermosensitive recording material and a method for producing the same, and more particularly, to a multicolor thermosensitive recording material suitable for double-sided recording of a multicolor image having a simple layer structure and excellent color separation. And its manufacturing method.

[0002]

2. Description of the Related Art Thermosensitive 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 is easy to handle, 4) has high color density, 5) is simple and inexpensive, and 6) has 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. As a multi-color heat-sensitive recording material that meets such demands, a recording material in which two kinds of color-forming components that form different colors at different color-forming temperatures are mixed and used in the same heat-sensitive color-forming layer (Japanese Patent Publication No. 49-69). Publication), a recording material in which a thermosensitive coloring layer having a high coloring temperature and a thermosensitive coloring layer having a low coloring temperature are sequentially laminated on a support (Japanese Patent Publication No. 51-199).
89, JP-A-54-88135, and 55-
Nos. 133911, 55-133992 and 48-15540), a heat-sensitive coloring layer having a high coloring temperature and a heat-sensitive coloring layer having a low coloring temperature are sequentially laminated on a support, and the heat-sensitive coloring layer is formed in the low-temperature heat-sensitive coloring layer. Recording material containing a decoloring agent having an effect of decoloring a coloring component (Japanese Patent Publication No.
Nos. 17866, 51-5791 and JP-A-55-161688) have been developed. Recently, for example, a microcapsule containing a color former such as an electron donating dye precursor is contained on a support, and a multicolor image is formed by laminating two or more monochromatic heat-sensitive recording layers that develop different hues. Multilayer thermal recording materials to be formed have been developed. Such a multicolor heat-sensitive recording material is excellent in storability, has good color separation properties, and can form a high-quality multicolor image.

[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 heat 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 tends to occur. In addition, the multicolor multilayer thermal recording material using microcapsules has a problem that the production cost is high.

By the way, the application range of such a heat-sensitive recording material is wide, and it is used in various places. For example, in ATM output sheets and various receipts of banks and the like,
In many cases, printing is performed not only on the front surface but also on the back surface in advance. If this backside printing can be performed at the same time as thermal recording of information on the front side at the same time, it is possible to save the trouble of printing the backside as well as the front side printing, and to produce a recording material such as a receipt. It is possible to greatly reduce the cost. However, black-and-white thermosensitive recording materials are known as such thermosensitive recording materials capable of double-sided printing, but a full-color (multicolor) thermosensitive recording material has not yet been provided.

[0005]

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, an object of the present invention is to provide a multicolor heat-sensitive recording material capable of performing double-sided recording of a multicolor image having a high sensitivity and a good color separation property, a high density and an excellent contrast while having a simple structure. I do. Another object of the present invention is to provide a multicolor heat-sensitive recording material that can be manufactured at low cost.
Still another object of the present invention is to provide a method for producing a multicolor heat-sensitive recording material capable of stably producing a high-quality multicolor heat-sensitive recording material.

[0006]

Means for solving the above problems are as follows. That is, <1> two or more kinds of electron-donating dye precursors that develop colors in different hues and an electron-accepting compound that causes the electron-donating dye precursors to develop color when heated on both surfaces of the support in the same layer. A multicolor heat-sensitive recording material having a heat-sensitive recording layer contained in,
The electron-donating dye precursor is one or more electron-donating dye precursors each encapsulated in a different microcapsule, and develops a different hue from the one encapsulated in the microcapsules to form solid fine particles. A multicolor heat-sensitive recording material comprising at least one kind of electron-donating dye precursor. <2> The multicolor heat-sensitive recording material according to <1>, wherein the heat-sensitive recording layer having the same hue is provided on one surface and the other surface of the support. <3> The multicolor heat-sensitive recording material according to <1>, wherein the heat-sensitive recording layers having different hues are provided on one surface and the other surface on the support.

<4> On one surface of the support, at least one electron-donating dye precursor encapsulated in different microcapsules, and a color different from that of the microcapsules. And at least one type of electron-donating dye precursor in the form of solid fine particles, two or more types of electron-donating dye precursors that form different colors.
Having a multicolor heat-sensitive recording layer containing an electron-accepting compound that causes the electron-donating dye precursor to develop color when heated, in the same layer,
On the other side of the support, there is provided a monochromatic heat-sensitive recording layer containing, in the same layer, an electron-donating dye precursor and an electron-accepting compound that causes the electron-donating dye precursor to develop color when heated. Is a multicolor heat-sensitive recording material.

<5> The multicolor heat-sensitive recording material according to any one of <1> to <4>, wherein the electron-accepting compound is a compound represented by the following general formula (I).

[0009]

Embedded image

[In the general formula (I), R represents 1 carbon atom.
An alkyl group of -20, an aralkyl group of 7-25 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 an arylsulfonyl group having 6 to 20 carbon atoms Represent. ]

<6> The thermosensitive recording layer has the following general formula (II)
And the multicolor heat-sensitive recording material according to any one of the above items <1> to <5>, containing at least one compound represented by the following general formula (III) as a sensitizer.

[0012]

Embedded image [In the general formula (II), R ¹ represents an aralkyl group. ]

[0013]

Embedded image [In the general formula (III), R ² and R ³ each independently represent an alkyl group or an alkoxy group. ]

<7> Any one of the above items <1> to <6>, wherein the volume average particle diameter of the electron-donating dye precursor, the electron-accepting compound and the sensitizer in the form of solid fine particles is 1.0 μm or less. The multicolor heat-sensitive recording material described in Crab. <8> The capsule wall of the microcapsule, wherein the capsule wall contains polyurethane and / or polyurea as a component.
The multicolor heat-sensitive recording material according to any one of <7>. <9> The method for producing a multicolor heat-sensitive recording material according to any one of <1> to <8>, wherein the heat-sensitive recording layer is applied by a free-fall curtain coating method. This is a method for producing a thermosensitive recording material.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The multicolor heat-sensitive recording material of the present invention and a method for producing the same will be described below. (Multicolor heat-sensitive recording material) The multicolor heat-sensitive recording material of the present invention has a heat-sensitive recording layer described below on both sides of a support, and if necessary, a protective layer and other heat-sensitive recording layers. Etc. and other layers. First, the heat-sensitive recording layer in the multicolor heat-sensitive recording material of the present invention will be described.

<Thermosensitive Recording Layer> As an embodiment of the thermosensitive recording layer in the multicolor thermosensitive recording material of the present invention, firstly, two or more kinds of electron-donating dye precursors having different hues on both sides of the support are provided. Thermosensitive recording layer (hereinafter sometimes simply referred to as a "multicolor thermosensitive recording layer") containing, in the same layer, a dye and an electron-accepting compound that causes the electron-donating dye precursor to develop a color when heated.
Secondly, the multicolor heat-sensitive recording layer is provided on one surface of the support, and the electron-donating dye precursor is provided on the other surface of the support. And a single-color heat-sensitive recording layer (hereinafter sometimes simply referred to as a “monochrome heat-sensitive recording layer”) containing, in the same layer, an electron-accepting compound that causes the electron-donating dye precursor to develop a color when heated. There is a second aspect).

Further, in the first embodiment, a multicolor thermosensitive recording layer having the same hue is provided on one side and the other side of the support, and one side of the support and the other side are provided. And a surface having a multicolor heat-sensitive recording layer having a different hue.

Here, of the two modes, the mode (first mode) in which the multicolor heat-sensitive recording layers are provided on both sides of the support will be described. The multicolor heat-sensitive recording material of the present embodiment,
Thermal recording in which two or more types of electron-donating dye precursors that develop colors in different hues and an electron-accepting compound that causes the electron-donating dye precursor to develop a color when heated are contained in the same layer on both sides of the support. A multicolor heat-sensitive recording material having a layer (multicolor heat-sensitive recording layer), wherein the electron-donating dye precursor comprises at least one electron-donating dye precursor encapsulated in different microcapsules; It comprises at least one kind of electron-donating dye precursor which develops a color different from that contained in the capsule and is in the form of solid fine particles. In this embodiment, the multicolor heat-sensitive recording layer is provided not only on one side of the support but also on the other side, so that heat is applied from both sides using two thermal heads to simultaneously apply heat to both sides. Thermal recording of color can also be performed.

When heat is applied to the multicolor heat-sensitive recording layer, of the two or more electron-donating dye precursors that develop a different hue, the electron-donating dye precursor dispersed in the layer in the form of solid fine particles Is easily melted due to direct heat and reacts with an electron-accepting compound (developer) under relatively low energy to develop a first color. Thereafter, when heat is further applied, the electron-donating dye precursor encapsulated in the microcapsules reacts with the electron-accepting compound (developing agent) passing through the microcapsules, and a second color different from the above hue Color. In this case, since the first color has already been developed, the hue after the second color has been developed will be a hue in which the first color and the second color are mixed. Therefore, when selecting a hue for the first color and the second color, it is preferable to set the first color to a lighter color than the second color.

In the present invention, three or more kinds of electron-donating dye precursors that develop different hues are used as the electron-donating dye precursors to form three or more colors. Can also be improved. In this case, one kind of electron-donating dye precursor is dispersed in a layer in the form of solid fine particles, and two or more kinds of electron-donating dye precursors that develop colors different from each other have different glass transition points. Each is encapsulated in another microcapsule made of a wall material. At that time, if the difference of the glass transition point (Tg) in each microcapsule is set to be 20 ° C. or more, good color separation properties can be obtained.

Also in this case, the hue obtained when the second and subsequent colors are formed is a mixed color with the color formed in the previous stage, so that the solid fine particle-shaped color forming agent is formed in a low energy region. Is preferably set to a light color, and the color former to be encapsulated in the microcapsules is preferably selected so as to become a darker color hue in order of increasing the glass transition temperature (Tg) of the microcapsules. That is, for example, when three types of electron-donating dye precursors are contained, yellow-red-black, magenta-blue-black, and the like are developed in order from the first color former that develops in the lowest temperature range. It is preferable to select the electron-donating dye precursor in such a manner.

As an embodiment (first embodiment) in which the multicolor heat-sensitive recording layers are provided on both surfaces of the support, the multicolor heat-sensitive recording layers having the same hue are provided on one surface and the other surface of the support. There is an embodiment having For example, an embodiment having a thermosensitive recording layer containing an electron-donating dye precursor in a combination of yellow (solid fine particles) -red (microcapsules) -black (microcapsules) on both surfaces of the support may be mentioned. In addition,
The "same hue" is contained in the multicolor heat-sensitive recording layer,
It means that the types of two or more kinds of electron donating dye precursors that develop colors different from each other are all the same.

On the other hand, as another embodiment, there is an embodiment in which a multicolor heat-sensitive recording layer having a different hue is provided on one surface and the other surface on the support. For example, on one side of the support,
It has a thermosensitive recording layer containing an electron-donating dye precursor in a combination of yellow (solid fine particles) -red (microcapsules), and has a blue (solid fine particles) -black (micro (Capsule) and a thermosensitive recording layer containing an electron donating dye precursor. Further, a multicolor heat-sensitive recording layer containing three or more kinds of electron-donating dye precursors may be combined, or a multicolor heat-sensitive recording layer containing two kinds of electron-donating dye precursors and three kinds of electron donation may be used. It may be combined with a multicolor heat-sensitive recording layer containing a chromatic dye precursor.

Next, an embodiment in which the multicolor heat-sensitive recording layer is provided on one side of the support and the monochromatic heat-sensitive recording layer is provided on the other side of the support (second embodiment) will be described. . The multicolor heat-sensitive recording material of the present embodiment is characterized in that, on one surface of a support, at least one kind of electron-donating dye precursor encapsulated in different microcapsules, and one encapsulated in the microcapsules. Consisting of at least one type of electron-donating dye precursor which is colored in different hues and is in a solid fine particle state,
A multicolor heat-sensitive recording layer (multicolor) containing, in the same layer, two or more kinds of electron-donating dye precursors that form different hues and an electron-accepting compound that causes the electron-donating dye precursor to develop a color when heated. Heat-sensitive recording layer), and the other surface of the support is provided with an electron-donating dye precursor and an electron-accepting compound that causes the electron-donating dye precursor to develop a color when heated. It has a thermosensitive recording layer (monochromatic thermosensitive recording layer).

Also in this embodiment, a multicolor heat-sensitive recording layer is provided on one side of the support and a monochromatic heat-sensitive recording layer is provided on the other side, so that heat is applied from both sides using two thermal heads. At the same time, multi-color thermal recording can be performed on one surface and single-color thermal recording can be performed on the other surface.

The multicolor heat-sensitive recording layer provided on one side of the support is the same as the “multicolor heat-sensitive recording layer” described in the first embodiment. Further, the monochromatic thermosensitive recording layer provided on the other surface of the support has one type of electron-donating dye precursor in the same layer and an electron-accepting dye for causing the electron-donating dye precursor to develop color when heated. Contains compounds. The electron-donating dye precursor may be contained in the layer in the form of solid fine particles dispersed in the layer, and from the viewpoint of improving the storability of the image, contained in the microcapsule and contained in the layer. May be.

As an embodiment in which the multicolor heat-sensitive recording layer is provided on one surface of the support and the monochromatic heat-sensitive recording layer is provided on the other surface of the support, for example, one surface of the support is provided. Has a thermosensitive recording layer containing an electron-donating dye precursor in a combination of yellow (solid fine particles) -red (microcapsules), and has black (solid fine particles) electrons on the other surface of the support. Examples include a mode having a heat-sensitive recording layer containing a donor dye precursor. In the multicolor heat-sensitive recording layer, 3
By containing at least three kinds of electron-donating dye precursors, it is possible to form three or more colors and to further enhance the color effect. Further, the monochromatic thermosensitive recording layer may use one kind of the same hue as any one of the two or more kinds of electron-donating dye precursors contained in the multicolor thermosensitive recording layer, May be used alone.

In the multicolor thermosensitive recording material of the present invention, the multicolor thermosensitive recording layer provided on both surfaces on the support or on one surface on the support is dispersed in the layer in the form of solid fine particles. By adjusting the saturated reflection density of the obtained electron-donating dye precursor to a color of 0.6 or less, low-density image recording (for example, tint block) without strict control of printing energy Etc.) can be printed. That is, even if there is a variation (for example, a thermal head) between the thermal recording apparatuses, it is possible to obtain an image recording with a substantially constant density. Here, the saturated reflection density means a density at an energy addition point at which the density does not increase further even when thermal energy is applied more. The density was measured using a Macbeth densitometer (manufactured by Macbeth; RD-9).
18 type).

Next, the electron-donating dye precursor, electron-accepting compound, sensitizer and other components used in the multicolor heat-sensitive recording material of the present invention will be described.

—Electron Donating Dye Precursor— Examples of the electron donating dye precursor include the following compounds. However, the present invention is not limited to these. That is, as the electron-donating dye precursor that develops black, for example, 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-anilinofluoran 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 them, as the electron-donating dye precursors that emit red light in terms of color sensitivity and background fog, 3-diethylamino-7-chlorofluorane and 3-diethylamino-6-methyl-7-chlorofluoran are used. 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, in the case of red color development, for the purpose of hue correction, it is a preferred embodiment to use a mixture of dyes of a red color development system having slightly different hues, for example, 3-diethylamino-7-chlorofluoran or To 3-diethylamino-6-methyl-7-chlorofluoran, 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide or 3,3'-bis (1-ethyl- 2
(Methyl-indol-3-yl) phthalide and the like, by adding a small amount of a chromogenic dye having a hue of the red-brushed family,
The hue can be adjusted to a color hue that strongly feels reddish.

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. 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-dibenzylaminofluorene. 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, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-
(6′-Dimethylamino) phthalide is preferred.

Examples of the electron-donating dye precursor that develops yellow color include 3,6-dimethoxyfluoran and 1-
(4-n-dodecyloxy-3-methoxyphenyl)-
1,3-bis- (4
-Dimethylaminophenyl) -3-bis (ethoxycarbonyl) methyl-1-propene, spiro [4H-3,1
-Benzoxazine-4,9 '-[9H] xanthone], 3', 6'-bis (hexyloxy) -2-phenyl, spiro [4H-3,1-benzoxazine-4,
9 '-[9H] xanthon], 3', 6'-bis (hexyloxy) -2- (2-thienyl), 2-phenyl-
4- (4'-diethylaminophenyl) -6- (4'-
Octyloxyphenyl) -pyridine and the like.
These electron donating dye precursors may be used alone, but can be used for hue 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,
0.5 to 0.7 μm is more preferable. If the volume average particle size exceeds 1.0 μm, the color sensitivity with the second color is liable to occur because the heat sensitivity is reduced.

The content (dry mass) of the electron donating dye precursor in the heat-sensitive recording layer is preferably in the following range. That is, the content of the electron-donating dye precursor contained in the form of solid fine particles is 0.05 to 1.0 g / m
² is preferable, and 0.1 to 0.5 g / m ² is more preferable.
If the content is less than 0.05 g / m ^2, the color density becomes low, when it exceeds 1.0 g / m ^2, the fog density of the non-image area is increased. In addition, for example, when performing tint block printing, when the saturation reflection density is 0.6 or less when the electron-donating dye precursor dispersed in the layer in the form of solid fine particles is adjusted to 0.6 or less, the content is appropriately adjusted according to the content. It is preferable to further consider the type and amount of the electron-accepting compound to be combined with the electron-donating dye precursor. Specifically, the content (application amount) is generally 0.1 g / m ² , and the content of the electron-accepting compound described below is preferably 5.0% by mass or less in order to achieve the saturated reflection density. It will be an indication of

The content of the electron-donating dye precursor to be encapsulated in the microcapsules may be determined for each color hue,
Alternatively, it can be appropriately selected according to the color tone of the second and subsequent colors, but is preferably 0.05 to 1.0 g / m ² per type,
0.1-0.5 g / m < ² > is more preferable. If the content is less than 0.05 g / m ^2, the color density becomes low, when it exceeds 1.0 g / m ^2, the fog density of the non-image area is increased.

-Electron-Accepting Compound- The electron-accepting compound is a compound that reacts with the electron-donating dye precursor when heated to form a 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, metal salts of aromatic carboxylic acids, acid clay, bentonite, and the like. Are JP-B-40-9309, JP-B-45-14039, JP-A-52-140483,
JP-A-48-51510, JP-A-57-210886
JP-A-58-87089, JP-A-59-1128
No. 6, JP-A-60-176795, JP-A-61-95
988, JP-A-63-65779, JP-A-6-72
No. 984 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.

[0046]

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In the general formula (I), R represents an alkyl group having 1 to 20 carbon atoms, 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, Represents an arylcarbonyl group having 7 to 20 carbon atoms, an alkylsulfonyl group having 4 to 20 carbon atoms, or an arylsulfonyl group having 6 to 20 carbon atoms.

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 is preferably 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 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 addition to the above electron accepting compounds,
1,1-bis (4-hydroxyphenyl) -ethane,
1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4′-dihydroxydiphenyl sulfide, 4,4′-thiobis (3-methyl-6-tert
-Butylphenol), 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 2,4-bis (phenylsulfonyl) phenol, 4-hydroxybenzophenone Phenol derivatives such as dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate,
-Sec-butyl-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenyl ether, benzoic acid, p- tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid,
Aromatic carboxylic acids such as 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid, 4-β-phenoxyethoxysalicylic acid Examples thereof include acids, phenolic compounds thereof, and metal salts thereof, for example, metal salts with polyvalent metals such as zinc, magnesium, aluminum and calcium. 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 present invention, when preparing a coating solution for the heat-sensitive recording layer, the electron-accepting compound is preferably used in the form of a solid dispersion, and the volume-average particle diameter of the electron-accepting compound is 1.0 μm The following is preferable, and 0.5 to 0.7 μ
m is more preferred. When the volume average particle size exceeds 1.0 μm, the thermal sensitivity decreases. 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 solution described later can be used.

The content (dry mass) of the electron-accepting compound in the heat-sensitive recording layer is preferably from 50 to 400 parts by mass, more preferably from 100 to 300 parts by mass, based on 100 parts by mass of the electron-donating dye precursor. preferable. When the content is less than 50 parts by mass, 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.

-Sensitizer- In the present invention, from the viewpoint of improving the sensitivity, it is preferable to include a sensitizer in the multicolor heat-sensitive recording layer and the monochromatic heat-sensitive recording layer. The multicolor heat-sensitive recording material of the present invention has the following general formula (II)
And at least one compound represented by the following general formula (III).

[0056]

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In the general formula (II), R ¹ represents an aralkyl group. The aralkyl group may be substituted or unsubstituted. Among the aralkyl groups, for example, a benzyl group, a substituted benzyl group and the like are preferable, and the substituent of the substituted benzyl group is more preferably an alkyl group or 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, in the present invention,
It is not limited to these.

[0059]

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In the general formula (III), R ² and R ³
Each independently represents an alkyl group or an alkoxyl group, and these may have a substituent. Among the above-mentioned alkyl groups, for example, a methyl group, an ethyl group, a propyl group, a butyl group and the like are preferable, and among the above-mentioned alkoxy groups, for example, a methoxy group, an ethoxy group and a propoxy group are preferable.

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

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

-Other Components- The heat-sensitive recording layer is provided within a range that does not impair the effects of the present invention.
If necessary, other components may be contained, as the other components, for example, a co-dispersion of stearic acid and a metal salt of stearic acid, a zinc compound, a heat-fusible resin,
Pigments, metal soaps, waxes, hindered phenol compounds, water-proofing agents, etc., and other known additives that can be used in the heat-sensitive recording layer (for example, oil-absorbing substances such as polyurea fillers,
Fatty acids, antistatic agents, ultraviolet absorbers, defoamers, conductive agents,
Fluorescent dye, surfactant) and the like.

It is preferable that the zinc compound is added to the heat-sensitive recording layer 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 from 10 to 400% by mass based on the content of the electron-accepting compound,
50-300 mass% is more preferable. The content is 1
If the amount is less than 0% by mass, the effect of improving the image storability may not be sufficient. If the amount exceeds 400% by mass, the effect of improving the image storability may not be sufficient, and the dispersion of the heat-sensitive recording layer in the coating solution may be stable. Properties may be reduced.

The addition of the heat-fusible compound to the heat-sensitive recording layer is preferred 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 and / or aliphatic amides and ureides. JP-A-58-57989
No. 58-87094, No. 61-58789, No. 62-109681, No. 62-132677, No. 6
Nos. 3,151,478 and 63,235,961.

The content of the heat-fusible compound in the heat-sensitive recording layer is preferably from 20 to 300 parts by mass, more preferably from 40 to 150 parts by mass, per 100 parts by mass of the electron-accepting compound.

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.

The addition of the metal soap to the heat-sensitive recording layer is preferable in that the releasability from the recording head during recording can be improved. Examples of the metal soap include polyvalent metal salts of higher fatty acids, and specific examples thereof include zinc stearate, aluminum stearate, 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. The melting point of the wax may be 40 to 120 ° C., for example,
Paraffin wax, polyethylene wax, carnauba wax, microcrystalline wax, canderia wax, montan wax, fatty acid amide-based wax and the like are preferred, and paraffin wax having a melting point of 50 to 100 ° C., more preferred is methylol stearamide, and the like. The content of the wax in the heat-sensitive recording layer is preferably from 5 to 200 parts by mass, more preferably from 20 to 150 parts by mass, per 100 parts by mass of the electron-donating colorless dye.

The hindered phenol compound preferably includes, for example, a phenol derivative in which at least one of the 2- or 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 water-proofing 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 crosslinking 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 thickness of the heat-sensitive recording layer is preferably 4 to 15 μm,
10 μm is more preferred.

<Support> As the support, for example,
Examples include paper supports such as high-quality paper, coated paper obtained by applying resin or pigment to paper, resin-laminated paper, high-quality paper having an undercoat layer, synthetic paper, and plastic films. As the smoothness of the support surface, in terms of dot reproducibility,
The smoothness specified by Jls-8119 is preferably 500 seconds or more, more preferably 800 seconds or more.

<Other Layers> -Protective Layer- 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 hydrolysate, polyacrylamide derivative, polyvinylpyrrolidone, polystyrene sodium sulfonate, sodium alginate, etc. Water-soluble polymers and styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate It can be formed by using a water-insoluble polymer such as Rujon.

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 the 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. Suitable examples of the surfactant include sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, and the like. Specifically, di- (n-hexyl) sulfosuccinic acid, di- (2-ethylhexyl) ) A sodium salt such as sulfosuccinic acid or an ammonium salt is preferred, and an anionic surfactant is preferred.

-Another thermosensitive recording layer-On one surface of the support, a multicolor thermosensitive recording layer is provided,
On the other side, a multi-color heat-sensitive recording layer or a single-color heat-sensitive recording layer may be provided, or another heat-sensitive recording layer may be further provided according to the purpose. Further, the multicolor heat-sensitive recording material of the present invention may have other layers such as a protective layer and another heat-sensitive recording layer, if necessary.

(Production Method of Multicolor Thermosensitive Recording Material) The multicolor thermosensitive recording material of the present invention comprises the multicolor thermosensitive recording layer on one side of the support and the multicolor thermosensitive recording layer on the other side. Although it has a heat-sensitive recording layer or a monochromatic heat-sensitive recording layer, the production method thereof is not particularly limited. For example, a coating solution for a heat-sensitive recording layer prepared as follows (hereinafter referred to as “thermosensitive recording layer”) The coating liquid for recording layer may be applied and dried by a known coating method. In the multicolor heat-sensitive recording material of the present invention, a production method in which a heat-sensitive recording layer is formed by coating by a free-fall curtain coating method is preferable.

<Preparation Method of Coating Solution for Thermosensitive Recording Layer> Here, a multicolor coating for a thermosensitive recording layer containing an electron-donating dye precursor in the form of solid fine particles and an electron-donating dye precursor encapsulated in microcapsules is described. A method for preparing the liquid will be described as an example. The coating solution for the heat-sensitive recording layer contains at least one microcapsule 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, a particle dispersion liquid having a volume average particle size of 1.0 μm or less (i) was added to a dispersion medium containing polyvinyl alcohol or the like and added with an electron-donating colorless dye in the form of solid fine particles for coloring in the lowest temperature range, followed by pulverization. ) Is prepared. Next, a particle dispersion having a volume average particle size of 1.0 μm or less (ii) was obtained by adding the electron accepting compound represented by the general formula (I) to a dispersion medium containing polyvinyl alcohol or the like and performing a pulverization treatment. ) Is prepared.

The coating solution for the heat-sensitive recording layer is prepared by mixing the particle dispersions (i) and (ii) in advance, and then adding two or more separately prepared electron donor dye precursor microcapsules to the mixture. It can be prepared by adding a capsule solution and homogenizing. Here, when other components such as a sensitizer are contained, it may be added at the time of preparing each particle dispersion, or simultaneously with the addition of the electron-donating dye precursor-encapsulated microcapsule solution in the mixed solution. Good. The method for preparing the electron-donating dye precursor-encapsulated microcapsule solution will be described later.

When other components such as a sensitizer are contained, a dispersion liquid (iii) in which other components are dispersed and dissolved in a separately prepared dispersion medium may be prepared in advance. In this case, the particle dispersions (i) and (ii) are combined with the dispersion (ii).
It can be prepared by adding and mixing i), further adding two or more kinds of separately prepared microcapsule solutions containing electron donating dye precursors, and homogenizing them. In addition,
In the case of a coating solution for a monochromatic thermosensitive recording layer, the coating solution can be prepared by adding and mixing the particle dispersions (i) and (ii) with the dispersion (iii). In addition, the particle dispersion (i
After adding i) to the dispersion liquid (iii) and mixing, the mixture is further homogenized by adding a separately prepared microcapsule liquid containing an electron-donating dye precursor.

The dispersion medium is usually 0.5 to 10
An aqueous solution of a water-soluble polymer of about mass% is suitably used.
When the concentration of the aqueous solution of the water-soluble polymer is too low, the viscosity of the dispersion medium is reduced, and the solid-dispersed particles may be easily precipitated.On the contrary, when the concentration is too high, the coating solution for the heat-sensitive recording layer may be used. In some cases, the handling properties such as an increase in viscosity and an inability to uniformly apply the coating may be reduced.

Examples of the water-soluble polymer include polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin-modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic salicylic anhydride. Copolymers, polyacrylic acid, polyacrylamide, methylol-modified polyacrylamide, starch derivatives, casein, gelatin and the like are used, and are used after being dissolved in an appropriate aqueous solvent. Among them, it functions as a protective colloid, and an electron-donating dye precursor of solid fine particles,
Alternatively, polyvinyl alcohol is preferable in that the dispersion stability of the electron-accepting compound represented by the general formula (I) is improved.

The dispersing or dissolving means used for preparing the particle dispersions (i) to (iii) can be appropriately selected from known dispersing apparatuses. For example, a ball mill, a sand mill, a horizontal sand mill, an attritor, Colloidal mills and the like.

Next, a method for preparing the microcapsule solution encapsulating the electron-donating dye precursor will be described. In the multicolor heat-sensitive recording layer of the heat-sensitive recording material of the present invention, one or more kinds of electron-donating dye precursors are encapsulated in microcapsules in addition to the electron-donating dye precursor used as a solid dispersion as described above. Used. The method for microencapsulation can be appropriately selected from conventionally known methods. For example, US Patent Nos. 2,800,457 and 2,800,458
No. 3,287,154, British Patent No. 990443, JP-B-38-19574, and JP-A-42-294, respectively.
No. 446, No. 42-771, interfacial polymerization described in U.S. Pat. Nos. 3,418,250 and 3,660,304, and polymer precipitation described in U.S. Pat.
US Pat. No. 4,001,140, a method using an isocyanate polyol wall material described in US Pat. No. 3,914,511, a method using an isocyanate polyol wall material described in US Pat.
U.S. Pat. Nos. 4,087,376 and 4,089,802 using urea-formaldehyde-based or urea-formaldehyde-resorcinol-based wall forming materials, U.S. Pat.
No. 5455 melamine-formaldehyde resin,
A method using a wall-forming material such as hydroxybrobyl cellulose, JP-B-36-9168, JP-A-51-9079.
No. 952807, electrolytic dispersion cooling method described in 9655074, U.S. Pat. No. 3,111,407, spray drying method described in British Patent No. 930422, JP-B-7 -73069, 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 electron-donating dye precursor is added to a hydrophobic organic solvent serving as a core of the capsule. The oil phase prepared by dissolution or dispersion is mixed with an aqueous phase in which a water-soluble polymer is dissolved, emulsified and dispersed by a homogenizer or the like, and then heated to cause a polymer formation reaction at the oil droplet interface, It is preferable to employ an interfacial polymerization method for forming a microcapsule wall of a polymer substance. The interfacial polymerization method can form capsules having a uniform particle size in a short time.

The microcapsules preferred in the present invention include, at room temperature, a wall material of the microcapsules (hereinafter, referred to as a wall material).
Sometimes simply referred to as the “capsule wall”. ) The substance isolation function prevents the contact between the substance inside and outside the capsule, and only when the heat is applied to a certain value or more, the substance becomes permeable to the capsule wall and the substance inside and outside the capsule can contact. It is. This characteristic can be freely controlled as a change in the physical properties of the capsule by appropriately selecting the material of the capsule wall, the capsule core substance (the substance contained in the capsule), the additives, and the like.

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 can 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 aqueous polymer solution (aqueous phase) or After mixing in an oily medium (oil phase) to be encapsulated, emulsifying and dispersing in water, and then heating, a polymer forming reaction occurs 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
Those described in 8-80191 and 48-84086 can also be used.

When forming the microcapsules, the electron-donating dye precursor to be encapsulated 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 biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diallylethane, solid compound at room temperature, oligomer oil,
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. 10-7-131311 and 9-106039 and Japanese Patent Application No. 62-75409 are exemplified. As the amount of the organic solvent used,
1 to 500 based on 100 parts by mass of the electron donating dye precursor
Parts by weight are preferred. Further, at the time of encapsulation, a so-called oil-less capsule may be used without using the above organic solvent.

When the solubility of the electron-donating dye precursor to be included in the organic solvent is low, a low-boiling solvent having high solubility can 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 charged into the aqueous phase, emulsification and dispersion are performed by a means such as a homogenizer.The water-soluble polymer has a function as a protective colloid capable of making the dispersion uniform and easy, and the emulsified aqueous solution is dispersed. Also acts as a dispersion medium for stabilizing. 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 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 particle dispersion (i) and the like, and for example, polyvinylpyrrolidone and the like. No. Since the microcapsule liquid is mixed with the particle dispersion (i) or the like containing an electron-donating dye precursor, an electron-accepting compound, or 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 in the particle dispersion (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 protective colloid. A material that does 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 amount of the surfactant to be added is from 0.1% to the mass of the oil phase.
5% 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. for the purpose of promoting 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 as the polymerization reaction proceeds, 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 volume average particle diameter of the microcapsules is preferably 20 μm or less, and more preferably 5 μm or less from the viewpoint of obtaining high resolution. 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 glass transition point of the microcapsule is usually 100 to
200 ° C is preferable, and 125 to 160 ° C is more preferable.

In the multicolor heat-sensitive recording layer of the multicolor heat-sensitive recording material of the present invention, two or more kinds of electron-donating dye precursors having different coloring hues are respectively encapsulated in separate microcapsules, so that the color , A multicolor heat-sensitive recording material can be produced. In order to make the coloring energy different, microcapsules having different glass transition points (Tg: temperature at which the substance becomes permeable) of the capsule wall are used,
Preferably, the difference in glass transition point (Tg) is 20 ° C. or more.
More than one kind of microcapsule is used.

As means for setting the glass transition point (Tg) between capsules at 20 ° C. or higher, specifically, the mixing ratio of an aliphatic isocyanate to an aromatic isocyanate is changed by mixing a isocyanate with a polyamine or a polyol. It is performed by changing the ratio, changing the reaction temperature of the encapsulation, and the like. The glass transition point is 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 rate.

In the present invention, as described above, when two or more types of electron-donating dye precursor-encapsulated microcapsule solutions are added to a mixture of various dispersions and the like, two or more types of electron-donating dye precursors are added. For each of the bodies, the method of microencapsulation is performed using different wall materials to prepare two or more types of microcapsule solutions having different capsule walls.

<Method of Applying Coating Solution for Thermosensitive Recording Layer> The multicolor thermosensitive recording material of the present invention is prepared by applying the coating solution for thermosensitive recording layer obtained as described above to both surfaces of a support by a known coating method. It can be prepared by coating and drying. Examples of the known coating method include a free fall curtain coating method and a coating method using an air knife coater, a blade coater, a bar coater, a gravure coater, a curtain coater, a wire bar, or the like. Among the coating methods, the free-fall curtain coating method is preferred for the multicolor heat-sensitive recording material of the present invention.

The free-fall curtain coating method is a method of forming a free-fall curtain made of a coating solution for a heat-sensitive recording layer and colliding the free-fall curtain with a support to perform coating.
It is described in Japanese Patent Publication No. 2-32153.

The free fall curtain coating method is a coating method suitable for thinning the heat-sensitive recording layer and for high-speed coating. Specifically, the coating liquid is sent from the coating liquid tank to the liquid supply head using a metering pump, and a certain amount is discharged in the width direction of the support by gravity through a slit provided in the liquid supply head. Form a free-falling vertical curtain. The free fall vertical curtain collides with the continuously running support and is applied to the support. Therefore, the amount of application to the support is measured in the form of the amount of liquid sent to the liquid supply head prior to application,
Since it is not measured by an air knife, a blade or the like after the application, a complicated device and operation for measuring the application amount are not required. In addition, the solid content particles in the coating solution are not selectively scraped off by the classification action, and the coating solution composition does not change with time even if the coating solution is circulated and reused.
It is easy to form a coating film having a desired composition, and it is possible to produce a high-quality heat-sensitive recording material.

Further, in the above-mentioned free-fall curtain coating method, the coating amount is determined by the ratio of the supply coating amount per unit time to the conveying speed of the support. It is an amount that can be formed stably, the amount is extremely small, and the coating speed is generally 1
About 000 m / min is enough. Therefore, this makes it possible to apply a thin film and reduce the drying load. That is, the free-fall curtain coating method is extremely excellent in suitability for high-speed coating and thin-film coating, and is suitable as a coating method used for a multicolor heat-sensitive recording material.

[0109]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 <Preparation of Capsule Solution A Containing Black Color Dye Precursor> 2-anilino-3-methyl-6-N-ethyl-N-sec-butylaminofluoran (manufactured by Nippon Soda Co., Ltd.) Name PSD18
4: 6 g of a dye precursor) and a polyisocyanate compound as a wall material (manufactured by Takeda Pharmaceutical; trade name: Takenate D110N)
12 g was dissolved in 12 g of petroleum capsule oil (KMC113; trade name: KMC113) and 10 g of ethyl acetate. This solution was treated with a 5% by mass aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co .; trade name: PVA-2170: saponification degree: 88)
%) 112 g, emulsified with an ace homogenizer (manufactured by Nippon Seiki) at 8000 rpm for 10 minutes, and further added 60 g of water and 0.5 g of tetraethylenepentamine,
Reaction at 65 ° C for 3 hours, capsule size 0.85μ
m of capsule liquid A containing a black coloring dye precursor was prepared.

<Preparation of Red Coloring Dye Precursor Dispersion (B-1)> 14 parts by mass of 3-dimethylamino-7-chlorofluorane, 6 parts by mass of 3-dimethylamino-6,8-dimethylfluorane , Concentration 5% partially saponified polyvinyl alcohol (manufactured by Kuraray Co .; trade name PVA-205: saponification degree 88)
%) Aqueous solution (80 parts by mass) was pulverized using a sand mill to obtain a red coloring dye precursor dispersion (B) having an average particle size of 0.6 μm.
-1) was prepared.

<Preparation of Sensitizer Dispersion> 20 parts by mass of 1-benzyloxynaphthalene and 70 parts by mass of a 5% aqueous solution of partially saponified polyvinyl alcohol (PVA-205) were pulverized using a sand mill to obtain an average. Particle size 0.6μm
Was prepared. <Preparation of Developer Dispersion> 20 parts by mass of 4-[[4- (1-methylethoxy) phenyl] sulfonyl] phenol (manufactured by Nippon Soda Co., Ltd .; trade name D-8) and a 5% concentration partially saponified polyvinyl alcohol (PVA-205) 70 parts by mass of an aqueous solution was pulverized using a sand mill, and the average particle size was 0.6 μm.
m of a developer dispersion was prepared. <Preparation of pigment dispersion> 40 parts by mass of calcium carbonate, water 6
0 parts by mass and 0.4 parts by mass of a 10% aqueous sodium hexametaphosphate solution were pulverized using a sand mill to prepare a pigment dispersion having an average particle diameter of 0.6 μm.

<Preparation of Coating Solution (1) for Thermosensitive Recording Layer> 5.0 parts by mass of the above capsule solution A, a dye precursor dispersion (B-
1) 0.20 parts by mass, sensitizer dispersion 5.0 parts by mass, developer dispersion 5.0 parts by mass, and pigment dispersion 5.0 parts by mass, 31% concentration of hydrin Z-7 ( Hydrin D337 having a concentration of 0.8% by mass and a concentration of 31%
(Trade name of Chukyo Yushi Co., Ltd.) 0.8 parts by mass, 2% of (2-
Ethylhexyl) sodium sulfosuccinate aqueous solution
0 parts by mass and 15.0 parts by mass of water were mixed to obtain a thermosensitive recording layer coating solution (1). <Preparation of thermosensitive recording paper> The thermosensitive recording layer coating solution (1) was applied on both sides of a paper support using a wire bar so that the mass of the dried thermosensitive recording layer was 8 g / m ^2. ,
After drying in an oven at 60 ° C., it was calendered so as to have a smoothness of 300 seconds (Beck method).

Example 2 <Preparation of Black Color Dye Precursor Dispersion (B-2)> 3-Di (n-butylamino) -6-methyl-7-anilinofluoran (Yamamoto Kasei; 20 parts by mass of trade name ODB2 and a 5% concentration partially saponified polyvinyl alcohol (manufactured by Kuraray; trade name PVA-205: saponification degree 88%) aqueous solution 80
And a mass part thereof were pulverized using a sand mill to prepare a black coloring dye precursor dispersion liquid (B-2) having an average particle diameter of 0.6 μm.

<Preparation of Coating Solution (2) for Heat-Sensitive Recording Layer> 2.5 parts by mass of the black color dye precursor dispersion (B-2), 5 parts by mass of the sensitizer dispersion prepared in Example 1, 5 parts by mass of a developer dispersion, 5 parts by mass of a pigment dispersion, and 0.8 part by mass of Hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.) having a concentration of 31%;
0.8 parts by mass of hydrin D337 (trade name, manufactured by Chukyo Yushi Co., Ltd.) having a concentration of 31%, 1.0 part by mass of a 2% aqueous solution of sodium (2-ethylhexyl) sulfosuccinate, and 15 parts of water
The mixture was mixed with parts by mass to obtain a thermosensitive recording layer coating solution (2). <Preparation of heat-sensitive recording paper> The heat-sensitive recording layer coating solution (1) prepared in Example 1 was coated on one side of a paper support using a wire bar so that the mass of the heat-sensitive recording layer was 8 g / m ^2. The heat-sensitive recording layer coating solution (2) is applied using a wire bar so that the mass of the heat-sensitive recording layer is 4 g / m ² on the opposite surface, and dried in a 60 ° C. oven. The calender processing was performed so as to be 300 seconds (Beck method).

Example 3 <Preparation of Capsule Solution C Containing Black Color Dye Precursor> The dye precursor was prepared by using 3-di (n-butylamino) -6-methyl-7-anilinofluoran (manufactured by Yamamoto Kasei Co., Ltd.). Product name: ODB2)
6 g, and the wall material was changed to 10 g of a polyisocyanate compound (manufactured by Takeda Pharmaceutical Co., Ltd .; Takenate D110N) and 2 g of Vernock D750 (manufactured by Dainippon Ink), and emulsification conditions were changed to 8000 rpm for 10 minutes. ,
Capsule liquid C was prepared in the same manner as capsule liquid A prepared in Example 1. The particle size was 0.77 μm.

<Preparation of Blue Dye Precursor Dispersion D>
(4-diethylamino-2-ethoxyphenyl) -3-
(1-ethyl-2-methylindol-3-yl) -4
-Azaphthalide (trade name: Blue6, manufactured by Yamamoto Kasei Co., Ltd.)
3: 20 parts by mass of a dye precursor) and a partially saponified polyvinyl alcohol having a concentration of 5% (manufactured by Kuraray Co., Ltd .; trade name PVA-20)
5: saponification degree: 88%) An aqueous solution (80 parts by mass) was pulverized using a sand mill to prepare a dye precursor dispersion D having an average particle size of 0.55 µm.

<Preparation of Sensitizer Dispersion> A sensitizer was prepared in the same manner as in Example 1 except that 20 parts by mass of 1-benzyloxynaphthalene was changed to 20 parts by mass of 1,2-diphenoxymethylbenzene. A dispersion was prepared. <Preparation of Developer Dispersion> 20 parts by mass of 4-[[4- (1-methylethoxy) phenyl] sulfonyl] phenol (manufactured by Nippon Soda Co .; trade name D-8) was added to 4-hydroxyphenyl-4 ′. A developer dispersion was prepared in the same manner as in Example 1, except that the amount was changed to 20 parts by mass of benzyloxyphenyl sulfone (trade name: BPS-BN, manufactured by Nikka Chemical Co., Ltd.).

<Preparation of Coating Solution (3) for Thermosensitive Recording Layer> 5.0 parts by mass of the capsule solution C and 0.1 part of the dye precursor dispersion D were added.
15 parts by mass, 5 parts by mass of a sensitizer dispersion, 5 parts by mass of a developer dispersion, and 5 parts by mass of a pigment dispersion, hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.) having a concentration of 31% 0.8 Hydrin D337 (parts by weight, manufactured by Chukyo Yushi Co., Ltd.) with a concentration of 31% by mass
0.8 parts by mass, 1.0 part by mass of a 2% aqueous solution of sodium (2-ethylhexyl) sulfosuccinate, and 15 parts by mass of water were mixed to obtain a thermosensitive recording layer coating solution (3). <Preparation of heat-sensitive recording paper> The heat-sensitive recording layer coating solution (3) was applied on both sides of a paper support using a wire bar such that the mass of the dried heat-sensitive recording layer was 8.5 g / m ^2. It was applied, dried in an oven at 60 ° C., and then calendered so as to have a smoothness of 300 seconds (Beck method).

(Example 4) <Preparation of thermosensitive recording layer coating solution (4)> 2.5 parts by mass of the dye precursor dispersion D prepared in Example 3 and the sensitizer dispersion prepared in Example 3 5 parts by mass, 5 parts by mass of a developer dispersion and 5 parts by mass of a pigment dispersion, 0.8 parts by mass of hydrin Z-7 (trade name, manufactured by Chukyo Yushi Co., Ltd.) having a concentration of 31%, and hydrin D337 having a concentration of 31% 0.8 parts by mass of Chukyo Yushi Co., Ltd.), 1.0 part by mass of a 2% aqueous solution of sodium (2-ethylhexyl) sulfosuccinate, and 15 parts by mass of water,
A thermosensitive recording layer coating solution (4) was obtained.

<Preparation of Thermal Recording Paper> Coating solution of thermal recording layer prepared in Example 3 using a wire bar on one side of a paper support so that the mass of the thermal recording layer was 8.5 g / m ^2. (3) was applied, and the mass of the heat-sensitive recording layer was 3 g /
The coating solution (4) for the heat-sensitive recording layer was applied using a wire bar so as to have a m ^{2 value} , dried in an oven at 60 ° C., and calendered so as to have a smoothness of 300 seconds (Beck method).

Example 5 <Preparation of Capsule Solution E Containing Cyan Dye Precursor> The dye precursor was converted to 3- (1-methyl-2-methylindol-3-yl) -3- (4-diethylamino-2-). Methylphenyl) -4-azaphthalide was changed to 6 g, and the wall material was a polyisocyanate compound (manufactured by Takeda Pharmaceutical; trade name Takenate D)
11N) and 1 g of Millionate MR400 (manufactured by Nippon Polyurethane Industry Co., Ltd.), and the emulsification conditions were changed to 8000.
A capsule solution E was prepared in the same manner as the capsule solution A of Example 1, except that the rpm was changed to 10 minutes. The particle size was 0.82 μm.

<Preparation of magenta dye precursor dispersion F>
20 parts by mass of 3,3′-bis (1-n-octyl-2-methylindol-3-yl) phthalide, 5% concentration partially saponified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name PVA)
(−205: saponification degree: 88%) An aqueous solution (80 parts by mass) was pulverized using a sand mill to prepare a dye precursor dispersion F having an average particle size of 0.55 μm. <Preparation of developer dispersion> 20 parts by mass of 4-[[4- (1-methylethoxy) phenyl] sulfonyl] phenol (manufactured by Nippon Soda Co., Ltd .; trade name D-8) was added to 4-β-phenoxyethoxy salicylic acid. Other than changing to 20 parts by mass of zinc,
A developer dispersion was prepared in the same manner as in Example 1.

<Preparation of Coating Solution (5) for Thermosensitive Recording Layer> 5 parts by mass of the capsule solution E and 0.15 part of the dye precursor dispersion F were prepared.
Parts by mass, 5 parts by mass of a developer dispersion, 5 parts by mass of a sensitizer dispersion prepared in Example 1, 5 parts by mass of a pigment dispersion, concentration 31
% Hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.) 0.8
0.8 parts by mass of Hydrin D337 (trade name, manufactured by Chukyo Yushi Co., Ltd.) with a concentration of 31% by mass, 1.0 part by mass of a 2% sodium (2-ethylhexyl) sulfosuccinate aqueous solution, and 15 parts by mass of water Thus, a thermosensitive recording layer coating solution (5) was prepared. <Preparation of thermosensitive recording paper> On both sides of a paper support, the mass of the thermosensitive recording after drying was 8.0 g / m ² .
The heat-sensitive recording layer coating solution (5) was applied using a wire bar, dried in an oven at 60 ° C., and then calendered to a smoothness of 300 seconds (Beck method).

(Example 6) <Preparation of heat-sensitive recording paper> On one surface of a paper support, a wire bar was used so that the mass of the heat-sensitive recording layer was 8.0 g / m ^2. The prepared heat-sensitive recording layer coating solution (5) was applied, and the heat-sensitive recording layer prepared in Example (2) was coated on the opposite surface with a wire bar so that the mass of the heat-sensitive recording layer was 3 g / m ^2. The solution (2) was applied, dried in an oven at 60 ° C., and then calendered so as to have a smoothness of 300 seconds (Beck method).

(Example 7) The heat-sensitive recording layer coating solution prepared in Example 5 was coated on one side of a paper support with a wire bar so that the mass of the heat-sensitive recording layer was 8.0 g / m ^2. (5) was applied, and the mass of the heat-sensitive recording layer was 8.5 g on the opposite surface.
/ M ² , using a wire bar, Example 3
The heat-sensitive recording layer coating solution (3) prepared in the above was applied and dried in an oven at 60 ° C., and then calendered so as to have a smoothness of 300 seconds (Beck method).

Example 8 <Preparation of Capsule Solution G Containing Magenta Coloring Dye Precursor>
3,3′-bis (1-n-octyl-2-methylindol-3-yl) phthalide (Ciba-Geigy; trade name Pergascript Red I-6)
B) 6 g, and 12 g of a polyisocyanate compound (manufactured by Takeda Chemical; trade name: Takenate D110N) as a wall material,
Petroleum capsule oil (Kureha Chemical Co., Ltd .; trade name KMC1)
13) Dissolved in 12 g and 10 g of ethyl acetate. 112 g of a 5% by mass aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name: PVA-217C: saponification degree: 88%)
And mixed with an ace homogenizer (Nippon Seiki)
The mixture was emulsified at 000 rpm for 10 minutes, further added with 60 g of water and 0.5 g of tetraethylenepentamine, and reacted at 50 ° C. for 3 hours to prepare a capsule solution G having a capsule size of 1.15 μm.

<Preparation of Capsule Solution H Containing Black Color Dye Precursor> 2-anilino-3-methyl-6-N-ethyl-N-
6 g of sec-butylaminofluoran (trade name: PSD184, manufactured by Nippon Soda Co., Ltd.) and Takenate D11 as a wall material
4 g of 0N (manufactured by Takeda Pharmaceutical) and 8 g of Vernock D750 (manufactured by Dainippon Ink) were dissolved in 12 g of petroleum capsule oil (manufactured by Kureha Chemical Co., Ltd .; trade name: KMC113) and 10 g of ethyl acetate. This solution was treated with a 5% by mass aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; trade name PVA-217).
C: 88% of saponification degree), and emulsified with an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.) at 6000 rpm for 8 minutes. Further, 60 g of water and 0.5 g of tetraethylenepentamine were added.
g was added and reacted at 65 ° C. for 3 hours to prepare a capsule solution H having a capsule size of 1.22 μm.

<Preparation of Yellow Color Dye Precursor Dispersion I> 1- (4-n-dodecyloxy-3-methoxyphenyl) -2- (2-quinolyl) ethylene (manufactured by Yamada Chemical Co., Ltd.)
Product name Y721) 20 parts by mass and 5% concentration partially saponified polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; product name PVA-20)
5: saponification degree: 88%) An aqueous solution (80 parts by mass) was pulverized using a sand mill to prepare a dye precursor dispersion G having an average particle size of 0.57 µm. <Preparation of Developer Dispersion> 20 parts by mass of 4-[[4- (1-methylethoxy) phenyl] sulfonyl] phenol (manufactured by Nippon Soda Co., Ltd .; trade name D-8) was added to bis (3-allyl-
A developer dispersion was prepared in the same manner as in Example 1 except that the amount was changed to 20 parts by mass of 4-hydroxyphenyl) sulfone.

<Preparation of Coating Solution (6) for Thermosensitive Recording Layer> 4 parts by mass of the capsule solution G, 4 parts by mass of the capsule solution H, 0.12 parts by mass of the dye precursor dispersion I, and the developer dispersion 5 parts by mass, 5 parts by mass of the sensitizer dispersion prepared in Example 1, 5 parts by mass of the pigment dispersion, 0.8 parts by mass of 31% hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.), concentration 0.8% by mass of 31% hydrin D337 (trade name, manufactured by Chukyo Yushi Co., Ltd.)
1.0 part by mass of a 2% aqueous solution of sodium (2-ethylhexyl) sulfosuccinate and 15 parts by mass of water were mixed to prepare a thermosensitive recording layer coating solution (6). <Preparation of heat-sensitive recording paper> The heat-sensitive recording layer coating solution (6) was coated on both sides of a paper support using a wire bar so that the mass of the heat-sensitive recording layer after drying was 10.0 g / m ^2. It was applied, dried in an oven at 60 ° C., and then calendered to a smoothness of 300 seconds (Beck method).

(Example 9) The heat-sensitive recording layer coating solution (6) prepared on Example 8 using a wire bar so that the mass of the heat-sensitive recording layer was 10.0 g / m ² on one side of a paper support. )
Is applied, and the heat-sensitive recording layer coating solution (4) prepared in Example 4 is applied to the opposite surface using a wire bar so that the mass of the heat-sensitive recording layer becomes 3 g / m ^2. And then calendered so as to have a smoothness of 300 seconds (Beck method).

Example 10 A heat-sensitive recording layer coating solution prepared in Example 8 using a wire bar so that the mass of the heat-sensitive recording layer was 10.0 g / m ² on one side of a paper support ( 6) is applied, and the mass of the heat-sensitive recording layer is 8.5 g on the opposite surface.
/ M ² using a wire bar to apply the heat-sensitive recording layer coating solution (1) prepared in Example 1 and drying in an oven at 60 ° C., resulting in a smoothness of 300 seconds (Beck method). As described above.

(Evaluation of multicolor heat-sensitive recording material) <Color-forming property and color-separation property> The color-forming density was measured using a thermo-sensitive printing tester (TH-PMH, manufactured by Okura Electric Co., Ltd.). in printing energy of mm ^2,
15, 40 and 70 mJ / mm for three colors respectively
^{2 with} the printing energy of ²
It was measured with a 918 type densitometer (manufactured by Macbeth). Also,
The color separation was observed and evaluated by comparison. Table 1 shows the results.

[0134]

[Table 1]

As shown in Table 1, it can be seen that the multicolor recording material of the present invention has good color separation properties and is capable of high-density and high-contrast multicolor double-sided recording.

[0136]

According to the present invention, there is provided a multicolor heat-sensitive recording material capable of double-sided recording of a multicolor image having a simple structure, high sensitivity, good color separation, high density and excellent contrast. be able to. Also, a low-cost multicolor heat-sensitive recording material can be provided. Further, according to the present invention, a high-quality multicolor heat-sensitive recording material can be stably manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41M 5/18 112

Claims (9)

[Claims] 1. An ink-jet recording method comprising the steps of: providing, on both sides of a support, two or more kinds of electron-donating dye precursors that form different hues and an electron-accepting compound that causes the electron-donating dye precursors to develop color when heated. A multicolor heat-sensitive recording material having a heat-sensitive recording layer, wherein the electron-donating dye precursor comprises at least one electron-donating dye precursor encapsulated in different microcapsules; A multicolor heat-sensitive recording material, which comprises at least one kind of electron-donating dye precursor which is colored in a different hue from that contained in the toner and is in the form of solid fine particles. 2. The multicolor heat-sensitive recording material according to claim 1, wherein a heat-sensitive recording layer having the same hue is provided on one surface and the other surface of the support. 3. The multicolor heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layers having different hues are provided on one surface and the other surface of the support. 4. One or more types of electron-donating dye precursors encapsulated in different microcapsules on one surface of a support, and a color different from the hue different from that encapsulated in the microcapsules. Two or more types of electron-donating dye precursors, each of which forms a different hue, comprising at least one type of electron-donating dye precursor in the form of solid fine particles, and an electron for causing the electron-donating dye precursor to develop color when heated. A multicolor heat-sensitive recording layer containing a receptive compound in the same layer, and on the other surface of the support, an electron-donating dye precursor and an electron for causing the electron-donating dye precursor to develop color when heated. A multicolor heat-sensitive recording material comprising a single-color heat-sensitive recording layer containing a receptive compound in the same layer. 5. The compound of the following general formula (I):
The multicolor heat-sensitive recording material according to any one of claims 1 to 4, which is a compound represented by the following formula: Embedded image [In the general formula (I), R represents an alkyl group having 1 to 20 carbon atoms, an aralkyl group having 7 to 25 carbon atoms, and 6 to 2 carbon atoms.
0 aryl group, C 5-20 alkylcarbonyl group, C 7-20 arylcarbonyl group, C 4
Represents an alkylsulfonyl group having from 20 to 20 or an arylsulfonyl group having from 6 to 20 carbon atoms. ] 6. The heat-sensitive recording layer according to claim 1, wherein the heat-sensitive recording layer contains at least one of the compounds represented by the following general formulas (II) and (III) as a sensitizer. Multicolor heat-sensitive recording material. Embedded image [In the general formula (II), R ¹ represents an aralkyl group. [Chemical formula 3] [In the general formula (III), R ² and R ³ each independently represent an alkyl group or an alkoxy group. ] 7. The method according to claim 1, wherein the volume average particle diameter of the electron-donating dye precursor, the electron-accepting compound, and the sensitizer in the form of solid fine particles is 1.0 μm or less. Multicolor thermal recording material. 8. The multicolor heat-sensitive recording material according to claim 1, wherein the capsule wall of the microcapsule contains polyurethane and / or polyurea as a component. 9. A method for producing a multicolor heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer is applied by a free-fall curtain coating method. Manufacturing method of recording material.