JP3402144B2 - Multicolor thermal recording material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and in particular, it develops multicolors having different color tones due to the difference in heating application conditions from a thermal head, and produces a reddish color tone of low-temperature printing and high temperature. There is little mixing of black coloration, which is the color tone at the time of color development, and black color development at high temperature has excellent readability with optical character readers and bar code readers that read in the near infrared region. Regarding materials.

[0002]

2. Description of the Related Art Conventionally, by utilizing a color forming reaction between a dye precursor, a dye precursor and a color developing agent which is brought into a color by being heated, both color forming substances are melt-contacted by heating,
A heat-sensitive recording material for obtaining a color image is widely known. Such a thermal recording material is relatively inexpensive,
Since the recording device is compact and easy to maintain, it can be used for facsimiles, word processors, various computers,
It is used in a wide range of fields as a recording medium for other purposes.

With respect to the heat-sensitive recording materials, the required quality has been diversified with the expansion of their applications. For example, there are demands for higher sensitivity, image stabilization, and multicolor recording.

The multi-color recording means has an advantage that a character or figure to be emphasized can be clearly displayed in a different color tone from other portions. Among them, a two-color heat-sensitive recording material capable of two-color recording of red and black is excellent in versatility and thus highly demanded for practical use.

As a multicolor thermosensitive recording system, attempts have been made so far to utilize a difference in heating temperature or a difference in thermal energy, and various multicolor thermosensitive recording materials have been proposed. Generally, a multicolor thermosensitive recording material is composed of a high-temperature coloring layer and a low-temperature coloring layer, which are colored in different colors on a support, and are sequentially laminated. Of 2
It is divided into types.

Examples of the decolorizable multicolor heat-sensitive recording material include, for example, JP-A-50-17865 and JP-A-57-14.
As disclosed in JP-A-320-80 and JP-A-2-80287, only the low-temperature color-developing layer develops color by a low-temperature color-developing operation, and upon high-temperature color-heating, the color-developing system of the low-temperature color-developing layer is erased. This is a method in which a decoloring agent having a color action acts to obtain color only in the high temperature color developing layer. This method has an advantage that the coloring tone can be freely selected, but it is necessary to add a large amount of a decoloring agent in order to obtain a sufficient decoloring effect for the low temperature coloring layer. Then, due to the action of the decoloring agent added in a large amount, the recorded color image is discolored during long-term storage, or an additional amount of heat is required to melt the decoloring agent, which causes an excessive load on the thermal head. However, there have been problems such as the reliability of the recorded image and the recording sensitivity.

On the other hand, the additive type multicolor thermosensitive recording material is
JP-B-49-27708, JP-B-51-1998
As described in JP-A No. 9 and JP-A No. 51-146239, a method of obtaining two distinguishable colors by laminating two color-developing layers that develop different colors and applying different amounts of heat. Is. In this method, at lower temperatures, the upper color layer develops color to obtain the upper layer color tone, and at high temperature, both upper and lower color layer layers develop color, and an image with a mixed tone of both colors is obtained. Suitable when used as a system. Since the decolorizing agent is not used in the additive type recording material, it is superior in long-term storage stability of the recorded image as compared with the decolorizing type.
Moreover, there is an advantage that it can be manufactured at a relatively low cost. Further, since there is no need for extra heat for melting the decoloring agent, there is an advantage that the high temperature coloring layer can be colored with low energy as compared with the decoloring type. However, the color-added multicolor heat-sensitive recording material having such a structure has a problem in that if too much heat is applied during low-temperature color development, color mixture in the high-temperature color development layer also partially mixes, making it difficult to obtain a clear low-temperature color development image. was there. Further, JP-A-56-99697 describes a method of mixing two or more kinds of dye precursors having different color tones and different average particle diameters in the same layer. There was a problem that color mixing became more intense.

Japanese Patent Publication No. 4-4960 and Japanese Unexamined Patent Publication No. 4-101885 disclose two or more types of microcapsules in which a color-forming component which develops a color tone different from each other is dissolved in a solvent and each of which has a different glass transition temperature. It is described that multicoloring is achieved by incorporating it in. However, when two or more dye precursors that develop different color tones are separately microencapsulated, the color development sensitivities of both dye precursors decrease, and sensitivity classification becomes difficult,
For this reason, there is a problem in that the color tones are easily mixed.

On the other hand, recently, a thermal image printed is often read by an optical character reading device or a bar code reading device, and in particular, reading having a wavelength in the near infrared region is performed. Since the device is small and inexpensive, it has been widely used.

However, since many of the fluoran-based leuco dyes that have been widely used so far do not exhibit absorption in the near-infrared region, their color formers have sufficient readability at wavelengths in the near-infrared region. There has been a strong demand for a multicolor heat-sensitive recording material having the dual function.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to develop multicolors having different color tones due to the difference in heating application conditions from a thermal head, and to produce reddish color tone of low temperature printing and high temperature color development. We provide a thermal recording material with little mixing of the black coloration that is the color tone of the color tone, and excellent readability with an optical character reader or bar code reader that reads the near infrared color black coloration at high temperature. To do.

[0012]

The present invention comprises a support, two or more dye precursors formed on the support and capable of developing different color tones, and the reaction with the dye precursor under heating. In a heat-sensitive recording material which has a heat-sensitive color-forming layer containing a color-developing compound which makes the color develop, the heat-sensitive color-forming layer comprises: (1) a first dye using a polyvalent isocyanate compound as a solvent; Composite fine particles obtained by emulsifying and dispersing a solution containing a precursor as a solute in water, and then accelerating the polymerization reaction of the polyvalent isocyanate compound, and (2) a second dye precursor that develops a reddish color tone. Solid fine particles composed of 1 in a thermosensitive color developing layer, and (3) the first dye precursor absorbs in the near infrared region with 100 parts by weight of the dye precursor which develops a near black color tone. Have a peak
Dye precursor to develop a color in the color tone of no green to blue system from 10 to 200
Multicolor heat-sensitive to the parts, characterized in that it comprises a mixture of a dye precursor 10 to 200 parts by weight <br/> having a strong absorption peak in colored shades of green to bluish, and near-infrared region It exists in the recording material.

The present invention also provides a support and a support formed thereon.
And two or more dyes that are colored in different tones
And the dye precursor react with the dye precursor under heating
It has a thermosensitive coloring layer containing a color-developing compound for coloring.
In a heat-sensitive recording material that develops in multiple colors,
The thermochromic layer (1) A polymer compound as a wall material and a high boiling point solvent as a solvent
Includes a solution containing the first dye precursor as a solute as a core substance
Microcapsules (2) A solid composed of a second dye precursor which develops a reddish color tone.
Body particles,OneContained in the thermosensitive coloring layer, and (3) The first dye precursor is before the dye that develops a black color tone
Body100 parts by weightWhen,Does not absorb in the near infrared regionGreen ~
Dye precursor that develops blue tones10-200 parts by weight
When,It develops green to blue tones, andStrong absorption in the near infrared region
IncomepeakDye precursor having10-200 parts by weightMixed with
It exists in a multicolor thermal recording material characterized by containing a compound.
It

In the multicolor thermosensitive recording material of the present invention, the first dye precursor is 100 parts by weight of 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane.
0-200 parts by weight of 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 10-20
There is a multicolor thermosensitive material containing a mixture with 0 parts by weight of 3,3 -bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide.

[0015]

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In a heat-sensitive recording material of the present invention, (1) a solution of a polyvalent isocyanate compound as a solvent and a first dye precursor as a solute is emulsified and dispersed in water, and then a polymer of the polyvalent isocyanate compound is obtained. With the composite fine particles obtained by accelerating the polymerization reaction, or, as a wall material a polymer compound, a microcapsule encapsulating a solution having a high boiling point solvent as a solvent and a dye precursor as a solute, as a core substance,
(2) Containing solid fine particles composed of a second dye precursor that develops a reddish color tone, and (3) a color-developing compound that comes into contact with the first and second dye precursors under heating to develop them. The heat-sensitive recording layer is provided on the sheet-shaped support. The first dye precursor is a mixture of a dye precursor that develops a black color tone, a dye precursor that develops a green to blue color tone, and a dye precursor that has strong absorption in the near infrared region. Contains.

In this case, the low temperature color tone is a reddish color tone which is the color tone of the second dye precursor existing in the state of solid fine particles, and the high temperature color tone is the first color present in the composite fine particles or microcapsules. A black-based color that is a color mixture with the color of the dye precursor is obtained. Further, since the high-temperature color image strongly absorbs light in the near infrared region, it is excellent in readability with an optical character reader or a bar code reader.

As the first dye precursor, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1- Ethyl-2-methylindole-3-
It is preferred to use a mixture of yl) -4-azaphthalide, 3,3 -bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide.

The composite fine particles used in the present invention are composed of a base material made of at least one polymer substance (resin) selected from polyurea or polyurethane-polyurea, and a dye precursor contained therein. The thing
It is considered that the dye precursor and the polymer substance exist in a solid solution state. From the viewpoint of pressure fog, it is desirable that the composite fine particles do not contain a liquid such as an oily solvent.

The colorant of the dye precursor contained in the composite fine particles has extremely good storage stability, especially excellent resistance to oil and plasticizer, as compared with the colorant formed in the solid fine particle state. . Although the reason is not always clear, it is considered that the color former and the polymer substance (base material) have some interaction and are stabilized.

The appearance of the composite fine particles used in the present invention is substantially spherical when observed by an electron microscope, or is red blood cell-like with some depressions. In the cross-section observation with an electron microscope, the shape is an internal substance, a porous body, or a hollow body. When applied to a multicolor heat-sensitive recording material, its average particle diameter is preferably 0.8 μm to 5.0 μm. If the average particle size is smaller than 0.8 μm, it becomes difficult to distinguish the color development sensitivity from the mixed dye precursors in the state of solid fine particles having different color development color tones, and color mixture may occur at low temperature color development. Average particle size is 5.0
If it is larger than μm, the color developing sensitivity is lowered, and it is not preferable because energy is excessively applied to the thermal head.

The microcapsules containing the dye precursor used in the present invention are those in which a solution of the dye precursor serves as a core material as a liquid part and is protected by a capsule wall material. It is clearly separated from the shell. Therefore, the existence state and shape of the dye precursor are significantly different from those of the composite fine particles containing the dye precursor, which is considered to exist in a solid solution state with the polymer.

When applied to a multicolor heat-sensitive recording material, its average particle diameter is preferably 0.8 μm to 5.0 μm. If the average particle size is smaller than 0.8 μm, it becomes difficult to distinguish the color development sensitivity from the mixed dye precursors in the state of solid fine particles having different color development color tones, and color mixture may occur at low temperature color development. Further, if the average particle size is larger than 5.0 μm, the color development sensitivity is lowered, so it is not necessary to apply energy to the thermal head excessively, which is not preferable, and pressure or frictional rubbing causes destruction of the capsule to cause ground coloration. There is a problem that it is easy. Therefore, it is desired that the first dye precursor is present in the composite fine particles, preferably from the microcapsules in which the dye precursor is encapsulated in the polymer in the oily liquid solution.

The composite fine particles used in the present invention and the dye precursor that can be contained in the microcapsules are:
Leuco compounds such as triaryl compounds, diphenylmethane compounds, thiazine compounds, spiro compounds, lactam compounds, and fluorane compounds can be preferably used. These dye precursors each give a unique color tone upon contact with a developer, and the color tone is black, red, magenta, orange, blue,
There are various colors such as green and yellow.

In the case of the heat-sensitive recording material of the present invention capable of multicolor coloring, it is a mixture of a dye precursor having a coloring tone of black type, green to blue type and a strong absorption in the near infrared region.
The same thermosensitive color developing layer contains composite fine particles or microcapsules containing a dye precursor and solid fine particles containing a second dye precursor that develops a reddish color tone. The low-temperature color tone is the color tone of the second dye precursor existing in the state of solid fine particles, and the high temperature color tone is the color tone of the first dye precursor and the second dye precursor present in the composite fine particles or the microcapsules. Become. By making the first dye precursor a mixture of black color and green-blue color, the high temperature color tone can be made black even if the color mixture of the second dye precursor occurs.

The color forming dye precursor to be contained in the composite fine particles or the microcapsules is not a single compound and has a black color forming property. It is preferable to have black coloring. In order to make the high temperature color tone closer to a pure black color tone, a dye precursor having a color tone different from that of the low temperature color tone, more preferably a dye precursor having a complementary color relationship is compounded with a black color developing dye precursor. It is contained in fine particles or microcapsules. When the low-temperature color tone is red, a dye precursor that develops blue or green is added to the composite fine particles or microcapsules together with the black dye precursor. As a matter of course, as the first dye precursor, in addition to the black-colored and green-blue-colored dye precursors, dye precursors having various color tones can be added to correct the color tone.

Further, by adding a color forming dye having strong absorption in the near infrared region to the color forming dye precursor contained in the composite fine particles or the microcapsules,
The heat-sensitive recording material has excellent readability with an optical character reader or bar code reader. Further, in the present invention, the second dye precursor that develops a reddish tone, the dye precursor that develops a blackish tone, the dye precursor that develops a green to blue tone and the near-infrared region It is also possible to obtain a multicolor thermosensitive recording material by using a first dye precursor containing a dye precursor having strong absorption in different thermosensitive coloring layers.

As a dye precursor which gives a black color, 3-
Pyrrolidino-6-methyl-7-anilinofluorane, 3
-Diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-isoamyl-N-ethylamino) -7- (o-chloroanilino) fluorane, 3
-(N-ethyl-p-toluidino) -6-methyl-7-
Anilinofluorane, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-
Anilinofluorane, 3-di-n-butylamino-6-
Methyl-7-anilinofluorane, 3-di-n-amylamino-6-methyl-7-anilinofluorane, 3-
(N-isoamyl-N-ethylamino) -6-methyl-
7-anilinofluorane, 3- (Nn-hexyl-N)
-Ethylamino) -6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino) -6-methyl-7-anilinofluorane, 3-
[N- (3-ethoxypropyl) -N-methylamino)
-6-Methyl-7-anilinofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-
Di-n-butylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7
-(2,6-Dimethylanilino) fluorane, 3-diethylamino-6-methyl-7- (2,4-dimethylanilino) fluorane, 2,4-dimethyl-6- (4-dimethylaminoanilino) fluorane , And 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-
Anilino fluoran etc. can be mentioned.

Among the above-mentioned dye precursors that give a black color development, 3-di-n-amylamino-6-methyl-7-anilinofluorane and 3-diethylamino-6-methyl-7, which are relatively excellent in light fastness. -(2,6-Dimethylanilino) fluorane, 3-diethylamino-6-methyl-7
-(2,4-Dimethylanilino) fluorane, 2,4-
It is preferably at least one selected from dimethyl-6- (4-dimethylaminoanilino) fluorane.

Examples of dye precursors which can be used in the present invention to develop a red color include 3,6-bis (diethylamino) fluorane-γ-anilinolactam and 3,6-bis (diethylamino) fluorane-γ- (p- Nitro) anilinolactam, 3,6-bis (diethylamino) fluorane-γ- (o-chloro) anilinolactam, 3-dimethylamino-7-bromofluorane, 3-diethylaminofluorane, 3-diethylamino-6- Methylfluorane, 3-diethylamino-7-methylfluorane,
3-diethylamino-7-chlorofluorane, 3-diethylamino-7-bromofluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylamino-
6,8-Dimethylfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-diethylamino-7-tert-butylfluorane, 3- (N-ethyl-N-tolylamino) -7-methylfluorane, 3-
(N-ethyl-N-tolylamino) -7-ethylfluorane, 3- (N-ethyl-N-isobutylamino) -6
Examples thereof include -methyl-7-chlorofluorane, 3- (N-ethyl-N-isoamylamino) -7,8-benzofluorane and the like.

Further, as a dye precursor giving a reddish color, 3-cyclohexylamino-6-chlorofluorane, 3-di-n-butylamino-6-methyl-7-bromofluorane, 3-di-n. -Butylamino-7,8-benzofluorane, 3-tolylamino-7-methylfluorane, 3-tolylamino-7-ethylfluorane, 2-
(N-Acetylanilino) -3-methyl-6-di-n-
Butylaminofluorane, 2- (N-propionylanilino) -3-methyl-6-di-n-butylaminofluorane, 2- (N-benzoylanilino) -3-methyl-
6-di-n-butylaminofluorane, 2- (N-carbobutoxyanilino) -3-methyl-6-di-n-butylaminofluorane, 2- (N-formylanilino)-
3-methyl-6-di-n-butylaminofluorane, 2
-(N-benzylanilino) -3-methyl-6-di-n
-Butylaminofluorane, 2- (N-allylanilino) -3-methyl-6-di-n-butylaminofluorane, and 2- (N-methylanilino) -3-methyl-
6-di-n-butylaminofluorane, 3-diethylamino-7-phenoxyfluorane, 3- (N-ethyl-
N-isoamylamino) -7-phenoxyfluorane can be mentioned.

Further, 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,3'-
3'-bis (1-ethyl-2-methylindole-3-
Yl) phthalide, 3,3′-bis (1-n-octyl-
2-methylindol-3-yl) phthalide, 7- (N
-Ethyl-N-isoamylamino) -3-methyl-1-
Phenylspiro [(1,4-dihydrochromeno [2,3
-C] pyrazole) -4,3'-phthalide], 7- (N
-Ethyl-N-isoamylamino) -3-methyl-1-
p-Methylphenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3'-phthalide], and 7- (N-ethyl-Nn-hexylamino) -3- Methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4,3 '
-Phthalide] can be mentioned as a red dye precursor.

As the dye precursor which gives a blue color,
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2)
-Methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) phthalide, 3 -(1-ethyl-2
-Methylindol-3-yl) -3- (2-methyl-
4-diethylaminophenyl) -4-azaphthalide, 3
-(1-Ethyl-2-methylindol-3-yl)-
3- (2-ethoxy-4-diethylaminophenyl)-
4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-n-hexyloxy-
4-diethylaminophenyl) -4-azaphthalide, 3-diphenylamino-6-diphenylaminofluorane and the like can be mentioned.

The dye precursor that gives a green color is 3
-(N-ethyl-Nn-hexylamino) -7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3- (N-ethyl-Np-tolylamino) -7- ( N-phenyl-N-methylamino) fluorane and the like can be mentioned.

Dye precursors that give a yellowish color are 3,6-dimethoxyfluorane and 1- (4-
n-dodecyloxy-3-methoxyphenyl) -2-
(2-quinolyl) ethylene and the like.

Dye precursors having absorption in the near infrared region include 3,3 -bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide and 3,3-bis [1,
1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3,3
-Bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,
5,6,7-Tetrachlorophthalide, 3,3-bis [1
-(4-Methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3- [p- (p-anilinoanilino) anilino]- 6-methyl-7-chlorofluorane,
3- [p- (p-dimethylaminoanilino) anilino]
-6-Methyl-7-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-
(6'-dimethylamino) phthalide, bis (p-dimethylaminostyryl) -p-tolylsulfonylmethane, 3
-[P- (p-dimethylaminoanilino) anilino]-
6-methylfluorane, 3-di (n-pentyl) amino-6,8,8-trimethyl-8,9-dihydro- (3,
2, e) pyridofluorane, 3-di (n-butyl) amino-6,8,8-trimethyl-8,9-dihydro-
(3,2, e) pyridofluorane, 3- [1,1-bis (p-diethylaminophenyl) ethylene-2-yl]
-6-Dimethylaminophthalide, 3- (pn-butylaminoanilino) -6-methyl-7-chlorofluorane, 2-mesidino-8-diethylamino-benz [C]
Examples include fluoran.

The thermosensitive recording paper of the present invention has a low-temperature color tone of reddish color and a high-temperature color tone of black color. Further, in order to improve the readability of bar codes and the like, the fine particles or microcapsules are mixed. 10 dye precursors present
0 to 2 parts by weight of a dye precursor that develops a black color tone and 10 to 2
Includes a mixture of 100 parts by weight of a dye precursor that develops a green to blue color tone, which is a complementary color of red, and 10 to 200 parts by weight of a dye precursor having a strong absorption in the near infrared region. Has been found to be effective. When the amount of the dye precursor that develops a green to blue color tone or the dye precursor that strongly absorbs in the near infrared region is 10 parts by weight or less, a sufficient complementary color effect and absorption in the near infrared can be obtained. Absent. On the other hand, when the amount of the dye precursor that develops a green to blue color tone exceeds 200 parts by weight,
Even if more than 200 parts by weight of the dye precursor, which has strong green and bluish colors at high temperature and has strong absorption in the near-infrared region, is not further improved in bar code readability. In the present invention, as a result of earnest studies, in particular, 100 parts by weight of 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane as a black coloring dye and 10 to 10 as a blue coloring dye. 200 parts by weight of 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2)
-Methylindol-3-yl) -4-azaphthalide and 10 to 200 parts by weight of a near infrared dye.
It has been found effective to include a dye precursor mixture in combination with 3,3 -bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide.

In the production of the composite fine particles used in the present invention, first, a solution is prepared by dissolving a dye precursor in a polyvalent isocyanate compound which is a polymer-forming raw material. The melting temperature at this time is preferably 60 ° C. or higher. If the melting temperature is lower than 60 ° C, the dye precursor may not be sufficiently dissolved in the polyvalent isocyanate compound, and uniform composite fine particles may not be produced. In the present invention, not only a polyvalent isocyanate compound but also a polyol compound or a polyamine compound may be added as a polymer-forming raw material, if necessary.

In the present invention, this solution is cooled if necessary and then emulsified and dispersed in an aqueous medium containing a protective colloid substance such as polyvinyl alcohol dissolved therein. The temperature at the time of emulsion dispersion is not particularly limited, but it is desirable to set the temperature at which isocyanate and water do not react rapidly. The equipment used for emulsification and dispersion is a high-speed rotating agitator such as a stirrer (mixer), homomixer, and disper, or a homogenizer (homogenizer) that uses ultrasonic waves, vibration, high pressure, electrostatic field, or a forced interval passage type. Examples thereof include a colloid mill, a roll mill, a roller mill, a media stirring type dispersing machine such as a sand mill, a sand grinder, an attritor, and a ball mill. Furthermore, the emulsified dispersion can be obtained by using any of the methods generally used for emulsification of fine particles, including a film emulsification method using porous glass and the like.

After emulsification and dispersion, if necessary, a reactive substance such as a water-soluble polyamine is added to polymerize the polymer-forming raw material to form composite fine particles of the dye precursor and polyurea or polyurethane-polyurea. Isocyanate reacts with water to form a urea bond and polymerize. Further, the polyol compound reacts with isocyanate to form a urethane bond. The polyvalent isocyanate compound that can be used in the present invention may be a polyol adduct of the polyvalent isocyanate compound, a biuret body, a multimer such as an isocyanurate body.

Examples of the polyvalent isocyanate compound include norbornene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate,
2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, 4,4'-diphenylmethane diisocyanate,
Polymeric diphenylmethane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 5
-Isocyanate-1- (isocyanatomethyl)-
1,3,3-trimethylcyclohexane, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4 '
-Diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate,
Propylene-1,2-diisocyanate, butylene-
1,2-diisocyanate, cyclohexylene-1,2
-Diisocyanates such as diisocyanate and cyclohexylene-1,4-diisocyanate may be mentioned.

Further, triisocyanates such as 4,4 ', 4 "-triphenylmethane triisocyanate and toluene-2,4,6-triisocyanate, 4,4'.
-Tetraisocyanates such as dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate, and the like. Examples of the adduct of a polyvalent isocyanate and a polyol include trimethylolpropane adduct of hexamethylene diisocyanate, trimethylolpropane adduct of 2,4-tolylene diisocyanate, trimethylolpropane adduct of xylylene diisocyanate, and tolylene diisocyanate. Isocyanate prepolymers such as hexanetriol adducts can be used.
In addition, these polyvalent isocyanate compounds such as biuret form of hexamethylene diisocyanate and isocyanurate form of hexamethylene diisocyanate can be used.

Examples of the polyol compound used as the polymer-forming raw material include ethylene glycol and 1,3-
Propanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,7
-Heptanediol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane, 1,
2-dihydroxybutane, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propanediol,
2,4-pentanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-
Cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,6-trihydroxyhexane, phenylethylene glycol, 1,1,
1-trimethylolpropane, hexanetriol, pentaerythritol, aliphatic polyols such as glycerin, 1,4-di (2-hydroxyethoxy) benzene,
Condensation products of aromatic polyhydric alcohols such as 1,3-bis (2-hydroxyethoxy) benzene and alkylene oxides, p-xylylene glycol, m-xylylene glycol, α, α′-dihydroxy-p-diisopropyl Benzene, 4,4'-dihydroxydiphenylmethane, 2- (p, p'-dihydroxydiphenylmethyl)
Benzyl alcohol, 4,4'-isopropylidene diphenol, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide,
Examples thereof include ethylene oxide adduct of 4,4′-isopropylidenediphenol, propylene oxide adduct of 4,4′-isopropylidenediphenol, and acrylate having a hydroxyl group in the molecule such as 2-hydroxyacrylate.

Of course, the polyisocyanate compound, the polyol compound and the like are not limited to the above compounds, and if necessary, several kinds of compounds may be used in combination.

Other polyamine compounds that can be used as the polymer-forming raw material in the present invention include:
For example, ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, piperazine, 2-methylpiperazine,
2,5-dimethylpiperazine, 2-hydroxytrimethylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, amine adducts of epoxy compounds and the like can be mentioned. Further, other polymer substances may be contained within a range not impairing the object of the present invention.

In the present invention, the solute used in the production of the composite fine particles has a melting point of 40 in addition to the dye precursor for the purpose of increasing the color development sensitivity.
An organic compound having a boiling point of 150 ° C or higher and a boiling point of 150 ° C or higher can be used together. As the organic compound having a melting point of 40 ° C. or higher and 150 ° C. or lower and a boiling point of 150 ° C. or higher that can be used in the present invention, aromatic ketone compounds, aromatic ether compounds, aromatic cyclic ester compounds and phenol compounds are preferably used. it can. A specific example is shown below.

The aromatic ketone compound is benzophenone, and the aromatic ether compound is 1,2-di (m).
Examples of -tolyloxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (2-methylphenoxy) ethane, and aromatic cyclic ester compounds include coumarin and phthalide. Examples of the phenol compound include p-benzyloxyphenol and the like. These organic compounds may be used alone or in combination of two or more.

The weight ratio of the dye precursor and the polyvalent isocyanate compound in the production of the composite fine particles is based on 100 parts by weight of the dye precursor in terms of color developing sensitivity and easiness of production.
The polyisocyanate compound is preferably 50 to 2000 parts by weight, more preferably 250 to 6 parts by weight.
It is 00 parts by weight. As the polyvalent isocyanate compound, it is desirable to select a liquid having a low viscosity at room temperature and having high solubility in the dye precursor. In particular, dicyclohexylmethane-4,4'-diisocyanate, norbornene diisocyanate, hexamethylene diisocyanate, isocyanurate of hexamethylene diisocyanate and the like can be preferably used because of their low viscosity.

In the present invention, the emulsifier (protective colloid agent) used for preparing the composite fine particles includes polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, modified polyvinyl alcohol such as sulfo group-modified polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, styrene- Water-soluble synthetic polymer compounds such as maleic anhydride copolymer salts and their derivatives can be used. If necessary, a surfactant and a defoaming agent may be used at the same time. The amount of the emulsifier used in preparing the composite fine particles is not particularly limited, but generally it is preferably 1 to 50% by weight, and more preferably about 3 to 30% by weight based on the weight of the composite fine particles.

The fine composite particles used in the present invention are known in addition to dye precursors, if necessary, UV absorbers, antioxidants, oil-soluble fluorescent dyes, release agents, and heat-sensitive recording materials. Such a sensitizer may be added. Such an additive substance is preferably solid at room temperature, but may be liquid. In particular, an ultraviolet absorber and a hindered phenol-based antioxidant can improve light resistance and can be preferably used. In particular, benzotriazole-based UV absorbers such as 2- (2-hydroxy-5-methylphenyl) -2H-benzotriazole are
It can be preferably used.

In producing the composite fine particles used in the present invention, an organic solvent which acts as a solvent for the dye precursor is mixed with a polyvalent isocyanate compound and used within a range not impairing the object of the present invention. You can also The amount used is 50% by weight or less, more preferably 20% by weight or less, based on the weight of the composite fine particles. When the amount used is more than 50% by weight, fogging prevention by pressure, which is the object of the present invention, cannot be prevented and unfavorable results may be given. The solvent is not particularly limited, and a solvent that acts as a solvent for the dye precursor and is hydrophobic can be used. Specifically, for example, tricresyl phosphate, phosphates such as octyldiphenyl phosphate, dibutyl phthalate, phthalates such as dioctyl phthalate, carboxylic esters such as butyl oleate, various fatty acid amides, Alkylated naphthalenes such as diethylene glycol dibenzoate, monoisopropyl naphthalene, diisopropyl naphthalene, 1-methyl-1-phenyl-1-
Alkylated benzenes such as tolylmethane, 1-methyl-1-phenyl-1-xylylmethane, 1-phenyl-1-tolylmethane, alkylated biphenyls such as isopropyl biphenyl, xenoxyalkanes such as o-phenylphenol glycidyl ether, In addition to acrylates such as trimethylolpropane triacrylate, esters of polyhydric alcohols and unsaturated carboxylic acids, chlorinated paraffin, and kerosene, ethyl acetate, butyl acetate, methylene chloride and the like can be mentioned. Of course, these may be used in combination of two or more kinds.

Further, at the time of polymerizing in the preparation of composite fine particles, a tin compound, a polyamide compound, as a reaction accelerator,
You may use together an epoxy compound, a polyamine compound, etc. In addition, when using a polyamine compound, it is preferable to use an aliphatic polyamine compound from the viewpoint that light resistance is not deteriorated.

The microcapsules used in the present invention can be prepared by various known methods. Generally, a core substance (oil-based liquid) obtained by dissolving the above-mentioned dye precursor in an organic solvent as necessary is aqueous. It is prepared by a method of emulsifying and dispersing in a medium and forming a wall film made of a polymer material around oily droplets. Specific examples of the polymer material that becomes the wall film of the microcapsule include, for example, polyurethane resin, polyurea resin, polyamide resin, polyester resin, polycarbonate resin, aminoaldehyde resin, melamine resin, polystyrene resin, styrene-methacrylate copolymer resin, Examples thereof include styrene-acrylate resin, gelatin, polyvinyl alcohol and the like. Among these, microcapsules having a wall film made of a polyurethane-polyurea resin or an aminoaldehyde resin are particularly preferably used because they have excellent heat resistance.

The microcapsules having a wall film made of an aminoaldehyde resin can be obtained by adding a wall film agent after emulsifying the core substance. Capsules having an aminoaldehyde resin membrane used in the present invention generally include urea, thiourea, alkylurea, ethylene urea, acetoguanamine,
At least one amine such as benzoguanamine, melamine, guanidine, biuret, cyanamide and at least one aldehyde such as formaldehyde, acetaldehyde, paraformaldehyde, glutaraldehyde, glyoxal, furfural, or an initial condensation product obtained by condensing them In-si using
It is produced by the tu polymerization method.

Microcapsules having a wall film made of a polyurethane-polyurea resin are capsule wall film agents such as a polyvalent isocyanate compound and a polyol compound that reacts with the polyvalent isocyanate compound, or an adduct of the polyvalent isocyanate compound and the polyol compound. It is mixed with a core substance that is a hydrophobic liquid to be emulsified, and is emulsified and dispersed in an aqueous medium in which a protective colloid substance such as polyvinyl alcohol is dissolved, and a polyamine compound is added if necessary, and the liquid temperature is raised to form a polymer. It is produced by causing a reaction. As the polyvalent isocyanate compound, the polyol compound, and the polyamine compound which are polymer-forming compounds, the same ones as those used for producing the composite fine particles containing the dye precursor can be used.

As the emulsifier (protective colloidal agent) used for the microencapsulation, the same ones as those used for producing the composite fine particles containing the dye precursor can be used, and various anions, nonions, cations or amphoteric water-soluble polymers can be used. A compound or the like is used. The amount of the emulsifier used is not particularly limited, but in general, when the polyurethane-polyurea resin is used as the wall film material, the total of the three of the wall film material, the dye precursor and the organic solvent used is used. On the other hand, it may be adjusted in the range of 1 to 50% by weight, preferably 3 to 30% by weight. In the case of an aminoaldehyde resin, the amount of the emulsifier used is generally adjusted in the range of 1 to 20 parts by weight, more preferably 3 to 10 parts by weight, based on 100 parts by weight of the hydrophobic core substance.

If necessary, the organic solvent used as the core material of the microcapsules can also be selected from the hydrophobic media that can be added during the production of the composite fine particles containing the dye precursor. In addition, generally, the lower the viscosity of the mixture of the capsule wall film material, the dye precursor and the organic solvent, the smaller the particle size after emulsification and the sharper the particle size distribution. It is also possible to use a low boiling point solvent together. Specific examples of such a low boiling point solvent include ethyl acetate, butyl acetate, methylene chloride and the like.

The amount of the organic solvent used is not particularly limited and should be adjusted in a timely manner according to the type and amount of the dye precursor used, and the type of organic solvent. Since it is preferable that the dye precursor is sufficiently dissolved, in the case of the polyurethane-polyurea resin, the ratio of the organic solvent to the total of the organic solvent, the dye precursor and the microcapsule wall film material is generally 10 to 60. It is desirable to adjust in the range of about 20% by weight, preferably about 20 to 60% by weight. Further, in the case of an aminoaldehyde resin, it is desirable that the amount is adjusted to 50 to 2000% by weight, preferably 100 to 1000% by weight, based on the dye precursor.

The amount of the capsule wall film material to be used is not particularly limited, but the organic solvent in the microcapsules may ooze out after long-term storage and the storage stability of the heat-sensitive recording material may be deteriorated. It is preferable to use a large amount of the wall film material as compared with the microcapsules, and in the case of the polyurethane-polyurea resin, the wall film is used for the total of the organic solvent, the dye precursor and the microcapsule wall film material. The proportion of wood is 35 to 70% by weight, preferably 35
Used in the range of up to 60% by weight. In the case of an aminoaldehyde resin, the wall film material is 30 to 300% by weight, preferably 35 to 2% by weight based on the total amount of the dye precursor and the organic solvent.
Used in the range of 00% by weight.

In the microcapsules containing the dye precursor used in the present invention, in addition to the dye precursor, an antioxidant, a release agent and the like can be added if necessary. In addition, a polyamide resin, an epoxy resin, a polyamine resin, or the like can be used together as a reaction accelerator during the microencapsulation.

In the present invention, in the case of a multicolor heat-sensitive recording material, the second dye precursor which develops a reddish tone which is a different tone from the first dye precursor contained in the composite fine particles or microcapsules is solid. Use in fine particles.
In this case, the second dye precursor is a sand grinder, attritor, ball mill,
Pulverized by various wet pulverizers such as Cobomill, and modified polyvinyl alcohol such as polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, and sulfo group-modified polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer salt and their In addition to a water-soluble polymer compound such as a derivative, if necessary, a surfactant, an antifoaming agent, etc. may be dispersed in a dispersion medium to prepare a dispersion liquid, and this dispersion liquid may be used for preparing a coating material for forming a thermosensitive coloring layer. it can. Further, after the dye precursor is dissolved in an organic solvent, this solution is emulsified and dispersed in water by using the water-soluble polymer as a stabilizer, and then the organic solvent is evaporated from the emulsion to be used as solid fine particles of the dye precursor. You can also In any case, the average particle size of the dispersed particles of the dye precursor used in the state of solid fine particles is preferably 0.2 to 3.0 μm, and more preferably 0.3 to 3.0 μm in order to obtain appropriate color development sensitivity. It is 1.0 μm.
Of course, it is also possible to use a dye precursor having the same color tone together with the composite fine particles in a solid fine particle state to obtain a monochromatic coloring thermosensitive recording material.

The color-developing compound used in the present invention is not particularly limited, but generally has a property of liquefying or dissolving by an increase in temperature and a property of developing a color by contacting with the dye precursor. Selected from those that have. Typical developing compounds include 4-tert-butylphenol, 4-acetylphenol, 4-tert.
-Octylphenol, 4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,4'-dihydroxydiphenylmethane, 4,4'-isopropylidenediphenol, 4,4'-dihydroxydiphenyl ether, 4,4'- Cyclohexylidene diphenol, 1,1-bis (4-hydroxyphenyl) -ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 4,4'-dihydroxydiphenyl sulfide, 4,4'- Thiobis (3-methyl-6-te
rt-butylphenol), 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, and bis (3-allyl-4-hydroxyphenyl) sulfone. Phenolic compounds can be mentioned.

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

In the present invention, it is particularly preferable to use a diphenylsulfone derivative containing a hydroxyl group in the molecule as a color-developing compound. Examples of such compounds include 4,4′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, 4-
Examples thereof include hydroxy-4'-isopropoxydiphenyl sulfone and bis (3-allyl-4-hydroxyphenyl) sulfone. Such a color-developing compound has a property of excellent storage stability of a color image. It is speculated that this is due to the strong electron-withdrawing property of the sulfone group of the color-developing compound. Further, in order to form a color image that is less likely to be discolored even when contacted with oil or a plasticizer, 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane or N is used as the color-developing compound. Preference is given to using-(p-toluenesulfonyl) -N'-phenylurea.

Generally, the color-developing compound is preferably used in an amount of 30 to 300 parts by weight, more preferably 50 to 200 parts by weight, based on 100 parts by weight of the composite fine particles. Of course, if necessary, two or more kinds of color-developing compounds can be used in combination.

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

In the present invention, a compound conventionally known as a sensitizer for heat-sensitive recording materials is used as the sensitizer which can be used for improving the color-developing sensitivity of heat-sensitive recording. For example, parabenzyl biphenyl, dibenzyl terephthalate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, di-o-chlorobenzyl adipate, 1,2-diphenoxyethane, 1,2-bis ( 3-methylphenoxy) ethane, di-p-methylbenzyl oxalate, di-p oxalate
-Chlorobenzyl, 1,2-bis (3,4-dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane, metaterphenyl, diphenyl, benzophenone and the like can be mentioned. Among these compounds,
When di-p-methylbenzyl oxalate and di-p-chlorobenzyl oxalate are used as sensitizers, a sensitizing effect with less fog can be obtained.

Additives such as a color-developing compound, an image stabilizer and a sensitizer used in the present invention are dispersed in water in the same manner as when the dye precursor is used in the form of solid fine particles to prepare a thermosensitive coloring layer. It may be mixed with this when the forming paint is prepared. It is also possible to dissolve these additives in a solvent and emulsify this in water using a water-soluble polymer compound as an emulsifier for use. Further, the image stabilizer and the sensitizer may be contained in the composite fine particles containing the dye precursor.

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

In the present invention, an adhesive is used as the other component material constituting the thermosensitive coloring layer, and if necessary,
Cross-linking agents, waxes, metal soaps, colored dyes, colored pigments,
And fluorescent dyes can be used. As the adhesive, those similar to those used in the undercoat layer, for example, polyvinyl alcohol and its derivatives, starch and its derivatives, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, ethyl cellulose and other cellulose derivatives, sodium polyacrylate , Polyvinylpyrrolidone, acrylamide-acrylic acid ester copolymer, acrylamide-
Acrylic ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, water-soluble polymer materials such as casein, gelatin and their derivatives, and polyvinyl acetate. Emulsions such as polyurethane, polyacrylic acid, polyacrylic acid ester, vinyl chloride-vinyl acetate copolymer, polybutylmethacrylate, ethylene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-butadiene-acrylic copolymer Examples thereof include latex of water-insoluble polymer such as polymer.

Further, in order to improve the water resistance of the thermosensitive coloring layer, a crosslinking agent for three-dimensionally curing the adhesive can be contained in the thermosensitive coloring layer. For example, aldehyde compounds such as glyoxal, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, dimethylolurea compounds, aziridine compounds, blocked isocyanate compounds, and ammonium persulfate and ferric chloride, and chloride. Inorganic compounds such as magnesium, sodium tetraborate, and potassium tetraborate, or at least one crosslinkable compound selected from boric acid, boric acid triesters, boron-based polymers, etc., is used as the total solid content of the thermosensitive coloring layer 100 parts by weight. On the other hand, it is preferably used in the range of 1 to 10 parts by weight.

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

The metal soap added to the thermosensitive coloring layer includes higher fatty acid polyvalent metal salts such as zinc stearate,
Aluminum stearate, calcium stearate,
And zinc oleate. When the heat-sensitive recording material of the present invention is used as a two-color heat-sensitive recording material, the inclusion of a colored dye and / or a colored pigment having a color tone having a complementary color relationship with the low-temperature color tone in the heat-sensitive color-forming layer means printing It is preferably used for adjusting the color tone of the previous recording material. If necessary, an oil repellent, a defoaming agent, or an oil repellent may be further added to the heat-sensitive color-developing layer within a range that does not impair the effects of the present invention.
Various additives such as a viscosity modifier can be added. The thermosensitive coloring layer has a coating amount of 2 to 20 g after drying on the undercoat layer.
/ M ² , more preferably 4 to 10 g / m ² .

In the present invention, the microcapsules containing the ultraviolet absorber or the solid fine particles of the ultraviolet absorber are contained in the heat-sensitive color forming layer or the protective layer provided thereon to significantly improve the light resistance. You can also Specific examples of the ultraviolet absorber include the followings. Salicylic acid-based UV absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-
Examples thereof include benzophenone-based ultraviolet absorbers such as dimethoxybenzophenone and 2-hydroxy-4-methoxy-5sulfobenzophenone.

Furthermore, 2- (2'-hydroxy-5 '
-Methylphenyl) benzotriazole, 2- (2'-
Hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-
Di-tert-butylphenyl) benzotriazole,
2- (2'-hydroxy-3'-tert-butyl-
5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-ter
t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-ter
t-amylphenyl) benzotriazole, 2- [2 ′
-Hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimido-methyl) -5'-methylphenyl] benzotriazole, 2- (2'-hydroxy-
5'-tert-octylphenyl) benzotriazole, 2- [2'-hydroxy-3 ', 5'-bis (α,
α-Dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-3′-dodecyl-
5'-methylphenyl) benzotriazole, 2-
[2'-hydroxy-4 '-(2 "-ethylhexyl)
Oxyphenyl] benzotriazole, polyethylene glycol (molecular weight about 300) and methyl-3- [3-te
rt-Butyl-5- (2H-benzotriazole-2-
Benzotriazole-based UV absorbers such as condensates with yl) -4-hydroxyphenyl] propionate, 2 ′
Examples thereof include cyanoacrylate-based UV absorbers such as ethylhexyl-2-cyano-3,3-diphenylacrylate and ethyl-2-cyano-3,3-diphenylacrylate. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

Among these ultraviolet absorbers, benzotriazole type ultraviolet absorbers are preferable, and particularly 2- (2'-
Hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-dodecyl -5'-
Methylphenyl) benzotriazole, 2- [2'-hydroxy-4 '-(2 "-ethylhexyl) oxyphenyl] benzotriazole, polyethylene glycol (molecular weight about 300) and methyl-3- [3-tert-butyl-5- (2H-benzotriazol-2-yl)-
A condensate with 4-hydroxyphenyl] propionate exhibits a particularly remarkable effect of improving light resistance and is therefore more preferable.

The addition amount of the microcapsules containing the ultraviolet absorber or the solid fine particles of the ultraviolet absorber is not particularly limited, but when it is contained in the thermosensitive coloring layer and in the protective layer provided on the thermosensitive coloring layer. In any case, the content is preferably about 5 to 70% by weight based on the total solid content of each layer. Particularly preferably 1
Adjust in the range of 5 to 50% by weight. If it is less than 5% by weight, the effect of improving the light resistance is poor, and if it is more than 70% by weight, not only the effect of improving the light resistance is poor, but also the sensitivity of the thermosensitive coloring layer may be lowered. The microcapsules containing the ultraviolet absorber or the solid fine particles of the ultraviolet absorber can improve the light resistance more effectively when they are contained in the protective layer than in the thermosensitive coloring layer.

The ultraviolet absorbent microcapsules used in the present invention can be prepared by various known methods. Generally, the solid or liquid ultraviolet absorbent at room temperature is dissolved in an organic solvent as necessary. It is prepared by a method of emulsifying and dispersing the obtained core substance (oily liquid) in an aqueous medium to form a wall film made of a polymer substance around the oily droplets. Specific examples of the polymer substance that becomes the wall film of the microcapsule include:
For example, polyurethane resin, polyurea resin, polyamide resin, polyester resin, polycarbonate resin, aminoaldehyde resin, melamine resin, polystyrene resin,
Examples thereof include styrene-methacrylate copolymer resin, styrene-acrylate resin, gelatin, polyvinyl alcohol and the like. Among these, in particular, a microcapsule having a wall film made of a polyurethane-polyurea resin or an aminoaldehyde resin has excellent heat resistance, and therefore, in a thermosensitive coloring layer or a protective layer for the purpose of preventing sticking to a thermal head. Exhibits an excellent accompanying effect of also fulfilling the function of the added inorganic pigment, moreover, the refractive index is low compared to the microcapsules and other pigments composed of other wall films, and because the shape is spherical, Even if added in a large amount to the protective layer, there is no fear of causing a decrease in concentration due to irregular reflection of light, and therefore it is preferably used.

The microcapsules containing an ultraviolet absorber used in the present invention are those in which the ultraviolet absorber is a core substance as a liquid part and is protected by the capsule wall material, and the dye precursor is highly The presence state, shape, and desired function are completely different from the composite fine particles containing the dye precursor which is considered to exist in a solid solution state with the molecule.

In the present invention, the addition of a fluorescent whitening agent to the heat-sensitive color forming layer and the protective layer also has the effect of improving light resistance and can be preferably used. Fluorescent brighteners are widely used as brighteners because they have the function of absorbing light in the ultraviolet region and emitting light in the visible light region of longer wavelength. The dye precursor contained in the composite fine particles used in the present invention has a property of easily decomposing and yellowing due to the light having a high energy in the ultraviolet region, but the fluorescent whitening agent makes the ultraviolet light more harmless in the long wavelength region. By changing to light, not only yellowing can be prevented but also an effect on whiteness can be obtained. Further, the decoloring of the printed portion by light can be improved by containing a fluorescent whitening agent.

The fluorescent whitening agent usable in the present invention includes:
Examples thereof include derivatives of pyrene, coumarin, oxazole, imidazole, imidazolone, pyrazole, benzidine, diaminocarbazole, naphthalic acid and diaminostilbenedisulphonic acid. More specifically, 1,2-bis (5-methyloxazol-2-yl) ethylene, β, 4-bis (5-methyloxazol-2-yl) -styrene, 3-ethyloxycarbonyl-7,8 -Benzocoumarin, N-methyl-4-methoxynaphthalene-1,8-dicarboxylic acid imide, 4- [3-
(4-Chlorophenyl) -5-phenyl-1-pyrazolin-1-yl] -sodium benzenesulfonate, 1,2-
Bis [4- (phenylaminocarbonylamino) -2-
Sodiumoxysulfonylphenyl] ethylene, 1,2
-Bis {4- [2- (p-sodiumoxysulfonylanilino) -4-bis (2-hydroxyethyl) amino-
1,3,5-triazin-6-yl] amino-2-sodiumoxysulfonylphenyl} ethylene and the like. Among these compounds, 1,2-bis {4- [2- (p is a diaminostilbene disulfonic acid derivative.
-Sodium oxysulfonylanilino) -4-bis (2
-Hydroxyethyl) amino-1,3,5-triazin-6-yl] amino-2-sodiumoxysulfonylphenyl} ethylene is also preferable from the viewpoint of easy handling during preparation of the coating solution.

The amount of the fluorescent whitening agent added is not particularly limited, but it is 0.5 with respect to the total solid content of the thermosensitive coloring layer.
It is preferably about 15% by weight. Particularly preferably, 1 to 1
It is adjusted to be in the range of 0% by weight. When the amount is less than 0.5% by weight, a sufficient effect cannot be obtained, and when the amount is more than 10% by weight, the background is colored by the color of the fluorescent whitening agent itself, and a thermal recording material having a poor natural paper feeling is not preferable.

In the present invention, a magnetic recording layer may be provided on the surface of the support on which the thermosensitive coloring layer is not provided or between the support and the thermosensitive coloring layer. The magnetic recording layer is
It is possible to use a magnetic recording layer that has been conventionally used for a magnetic ticket, a prepaid card, a magnetic commuter pass, and the like. When the magnetic recording layer is provided between the support and the thermosensitive coloring layer, of course, even when it is provided on the surface of the support on which the thermosensitive coloring layer is not provided, it is applied before the thermosensitive coloring layer is applied. Is desirable for keeping the whiteness of the thermosensitive coloring layer high.

In the present invention, an undercoat layer which has been used in conventionally known heat-sensitive recording materials can also be used. Particularly when paper is used as a support, it is desirable to provide an undercoat layer. By using a pigment having a high porosity such as silica or calcined kaolin for the undercoat layer, the color developing sensitivity of the thermosensitive color developing layer can be increased. Incorporation of plastic pigments, hollow particles, foams, etc. in the undercoat layer is also effective in improving the color development sensitivity of the thermosensitive color development layer formed thereon.

In the present invention, it is desirable to provide a protective layer containing a water-soluble polymer material and a pigment as used in conventionally known heat-sensitive recording materials on the heat-sensitive color developing layer. As the water-soluble polymer material and the pigment, the materials exemplified for the thermosensitive coloring layer can be used. At this time, it is more desirable to add a crosslinking agent to impart water resistance to the protective layer. Such a protective layer is coated on the thermosensitive color developing layer so that the coating amount after drying is 0.5 to 10 g / m ² . The coating amount is more preferably 1 to 5 g / m ² .

In the present invention, a resin layer cured with an electron beam or an ultraviolet ray may be provided on the thermosensitive coloring layer or the protective layer. As an example of a resin cured by an electron beam, Japanese Patent Application Laid-Open No.
No. 8-177392, JP-A-58-177392 and the like. In such resin, non-electron beam curing resin, pigment, and defoaming agent, leveling agent, lubricant,
Additives such as surfactants and plasticizers can be added as appropriate. In particular, it is preferable to add pigments such as calcium carbonate and aluminum hydroxide, and lubricants such as waxes and silicon because they help prevent sticking to the thermal head. The resin layer cured with an electron beam or an ultraviolet ray is applied so that the coating amount after drying is 0.5 to 10 g / m ² . The coating amount is more preferably 1 to 5 g / m ² .

In the present invention, it is possible to print with UV ink, flexo ink or the like. In this case, the printing may be performed on any layer such as the heat sensitive layer, the protective layer, the electron beam curable resin layer, or the ultraviolet curable resin layer.

There are no particular restrictions on the type, shape, dimensions, etc. of the support material used in the present invention. For example, high-quality paper (acidic paper, neutral paper), medium-quality paper, coated paper, art paper, cast In addition to coated paper, glassine paper, resin laminated paper, polyolefin synthetic paper, synthetic fiber paper, non-woven fabric, synthetic resin film and the like, various transparent supports and the like can be appropriately selected and used. When the present invention is used for magnetic ticket applications, it is desirable to use paper, but when the present invention is used for prepaid cards or magnetic commuter pass applications, a plastic substrate made of polyethylene terephthalate having a thickness of 100 μm or more is used. It is desirable to use a material, particularly a foamed base material, from the viewpoint of heat-sensitive color development sensitivity. Of course, a laminated base material of a foamed polyethylene terephthalate film and a non-foamed polyethylene terephthalate film can also be used.

In the present invention, in order to increase the added value of the thermosensitive recording material, the thermosensitive recording material can be further processed to give a thermosensitive recording material having higher functions. For example, the back surface may be coated with an adhesive, a rewetting adhesive, a delayed tack type adhesive, or the like to give an adhesive paper, a rewetting adhesive paper, or a delayed tack paper. In particular, the heat-sensitive recording material of the present invention, which has been subjected to an adhesive treatment, is useful as a heat-sensitive label because of its good storability. Further, by utilizing the back surface, it is possible to impart a function as a thermal transfer paper, an inkjet paper, a carbonless paper, an electrostatic recording paper, or a xerographic paper to the recording paper, which enables double-sided recording. Of course, a double-sided heat-sensitive recording material can also be used.

As a method for forming each of the above layers on the support, known coating methods such as an air knife method, a blade method, a gravure method, a roll coater method, a spray method, a dip method, a bar method, and an extrusion method are used. Either may be used. Further, a back layer may be provided to suppress the penetration of oil or plasticizer from the back surface of the recording material or to control curl. Smoothing the heat-sensitive recording surface using a known smoothing method such as a super calender or a soft calender is effective in increasing the coloring sensitivity. The heat-sensitive recording surface may be treated by applying it to either a metal roll or an elastic roll of a calender.

[0091]

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the invention.
Unless otherwise specified, “part” and “%” indicate “part by weight” and “% by weight”, respectively.

(1) Preparation of materials used for undercoat layer, thermosensitive coloring layer and protective layer <Preparation of composite fine particle dispersion containing color forming dye precursor> Table 1
The chromogenic dye precursor having the compounding ratio shown in (4) was dissolved in 24 parts of dicyclohexylmethane-4,4'-diisocyanate heated to 100 ° C., and the solution was cooled to 25 ° C., and then 8% polyvinyl alcohol (Japan Synthetic Chemical Industry, trademark: Gohsenol GM-14L) was gradually added to 250 parts of an aqueous solution, and TK homomixer (model HV-M,
(Made by Tokushu Kika Kogyo Co., Ltd.) and emulsified and dispersed by stirring at a rotation speed of 5000 rpm.
Parts were added and homogenized. The emulsified dispersion is heated to 80 ° C. and allowed to undergo a curing reaction for 10 hours to give an average particle diameter of 1 to 2.
A dispersion liquid of composite fine particles containing a color-developing dye precursor having a size of μm was prepared.

<Preparation of Microcapsules Encapsulating Color-Developing Dye Precursor> One color-forming dye precursor having the compounding ratio shown in Table 1 was used.
After dissolving in 18 parts of tricresyl phosphate heated to 00 ° C. and cooling to room temperature, dicyclohexylmethane-4,4 '
-Add 6 parts of diisocyanate, gradually add this solution to 250 parts of 8% polyvinyl alcohol (Nippon Gosei Kagaku Kogyo, trademark: Gohsenol GM-14L) aqueous solution.
K homomixer (model HV-M, manufactured by Tokushu Kika Kogyo Co., Ltd.)
Was emulsified and dispersed by stirring at a rotation speed of 5000 rpm, and 100 parts of water was added to this emulsified dispersion for homogenization. This emulsified dispersion was heated to 80 ° C. and allowed to undergo a curing reaction for 10 hours to prepare a dispersion of microcapsules containing color-forming dye precursors having an average particle diameter of 1 to 2 μm.

<Preparation of Dye Precursor in Solid Fine Particle State, Color-Developing Compound, Sensitizer Dispersion> Red Coloring Dye Precursor: 3-Diethylamino-7-chlorofluorane Black Coloring Dye Precursor: 3- Di (n-pentyl) amino-6-methyl-7-anilinofluorane green to blue color forming dye precursor: 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-Azaphthalide near infrared absorbing dye precursor: 3,3 -bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide color developing compound: bis (3-allyl-4-hydroxyphenyl) sulfone sensitized Agent: Di-p-methylbenzyl oxalate

The above dye precursor, the color-developing compound, and the sensitizer were separately mixed with polyvinyl alcohol at the following compounding ratios, and each mixture was subjected to vertical sand mill (sand grinder manufactured by AIMEX Co., Ltd.). Then, it was pulverized and dispersed so that the average particle diameter was 1.2 μm to obtain a dispersion liquid of each compound in the form of solid fine particles.

[0096]                 Amount of ingredients (parts by weight)   Each compound 40   Polyvinyl alcohol 10% liquid 40   (Polymerization degree 500, Saponification degree 90%)   Water 20

<Preparation of Inorganic Pigment Dispersion> Silica was mixed with sodium polyacrylate in the following blending ratio, and this mixture was dispersed with a Cowles disperser. Ingredient Amount (parts by weight) Silica 50 Sodium polyacrylate 1.0% solution 50

Separately, an aqueous solution of polyvinyl alcohol (NM11Q, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a solid content of 10% was used as an adhesive solution, and an aqueous zinc stearate dispersion having a solid content of 21% (Z- was used as a lubricant dispersion). 7. Chukyo Yushi Co., Ltd. was prepared.

(2) Formation of undercoat layer The pigment dispersion liquid and the adhesive liquid are mixed at a solid content ratio of 8
It is blended so that it becomes 0:20, and this coating material is applied to a high-quality paper (neutral paper) having a basis weight of 60 g / m ² by using a Mayer bar.
2.0 g / m ² (dry) was applied to form an undercoat layer.

(3) Formation of thermosensitive color developing layer The solid content ratio is shown in Table 2 in Examples 1 to 4 and Comparative Examples 1 to 6.
The thermosensitive color developing layer coating solution formulated so as to correspond to the above was applied onto the undercoat layer formed earlier using a Mayer bar so that the coating amount was 8.0 g / m ² (dry), A color forming layer was formed.

(4) Formation of protective layer Solid content ratio of the above pigment dispersion, adhesive liquid and lubricant
, But the protective layer coating liquid was formulated so as to be 40: 55: 5
3.0 g / m on the thermosensitive coloring layer that was previously formed ²Coating
Apply with a Mayer bar to the amount (dry),
Each heat-sensitive recording material before the smoothing treatment was obtained.

The heat-sensitive recording material thus obtained was supercalendered and the Beck smoothness (JIS
-P8119) was smoothed for 200 to 250 seconds to obtain heat-sensitive recording materials corresponding to Examples and Comparative Examples.

Evaluation of two-color color heat-sensitive recording material Regarding the two-color color heat-sensitive recording material of Table 2, one line recording time: 5 msec, sub-scanning linear density: Solid printing of 256 lines was performed under the conditions of 8 lines / mm and applied energy per dot: 0.5 mJ, and red color recording was performed in low temperature printing. Separately, 1 line recording time: 5 msec, sub-scanning line density: 8 lines / mm, applied energy per dot:
Solid printing of 256 lines was performed under the condition of 2.0 mJ, and black color recording was performed in high temperature printing.

With respect to the colored product thus obtained,
The color separation property was visually evaluated. O indicates that clear red color development was obtained in low temperature color development and black color development was obtained in high temperature color development. Δ indicates that red, which was colored at low temperature, was mixed with black, which was colored at high temperature, slightly. X indicates that sufficient color separation could not be performed, such as mixing of the low-temperature color tone with red and black and the high-temperature color tone not being sufficiently black.

For the two-color color thermosensitive recording materials in the near-infrared reading evaluation table 2, one line recording time: 5 msec, sub scanning line density: 8 lines / mm, the applied energy per dot: 2.0 mJ, the barcode is printed, and the symbol verification machine La is manufactured by Symbol Corporation.
The bar code readability at a wavelength in the near infrared region of 680 nm was evaluated by serCheck II. Evaluation is ANSI
Comprehensive evaluation points (Overall Qual
It was performed in the "Itity Grade". A to D are in the pass level, and in that, the readability becomes worse in the order of A, B, C, and D. Although F can barely be read, the quality as a bar code is a failure level.

[0106]

[Table 1]

[0107]

[Table 2]

[0108]

EFFECTS OF THE INVENTION According to the present invention, multicolors having different color tones are developed due to the difference in the condition of applying heat from the thermal head, and the reddish tone of low temperature printing and the blackish tone of high temperature coloring. It is possible to manufacture a multicolor thermal recording material with little color mixture and excellent readability with an optical character reader or bar code reader that reads black color in high temperature printing in the near infrared region. It has become possible.

Continuation of the front page (56) Reference JP-A-57-151388 (JP, A) JP-A-6-122278 (JP, A) JP-A-6-345760 (JP, A) JP-A-9-142025 (JP , A) JP 9-0776634 (JP, A) JP 11-58950 (JP, A) JP 10-119438 (JP, A) JP 9-295457 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41M 5/28-5/34

Claims (3)

(57) [Claims] 1. A support, two or more kinds of dye precursors formed on the support, which develop different colors, and a color-developing compound that reacts with the dye precursor under heating to develop the color. A thermosensitive recording material containing a thermosensitive color developing layer containing and a multicolored thermosensitive recording material, wherein the thermosensitive color developing layer comprises (1) a solution containing a polyvalent isocyanate compound as a solvent and a first dye precursor as a solute; after emulsification and dispersion in water, the composite fine particles obtained by promoting the polymerization reaction of the polyvalent isocyanate compound, and a solid particulate of a second dye precursor which develops color tone of the (2) reddish one And (3) the first dye precursor contained in one thermosensitive coloring layer has 100 parts by weight of the dye precursor that develops a black color tone, and does not have an absorption peak in the near infrared region.
Dye precursor 10 to 200-fold coloring in shades of green to bluish have
The amount unit and multicolor heat-sensitive recording material which comprises a mixture of a dye precursor 10 to 200 parts by weight having a strong absorption peak in colored shades of green to bluish, and near-infrared region. 2. A support, two or more kinds of dye precursors formed on the support, which develop different colors, and a color-developing compound that reacts with the dye precursor under heating to develop the color. A thermosensitive color recording layer containing a thermosensitive color developing layer containing, and a thermosensitive color developing layer comprising: (1) a polymer compound as a wall material, a high boiling point solvent as a solvent, and a first dye precursor Microcapsules containing a solution containing the body as a solute as a core substance, and (2) solid fine particles composed of a second dye precursor that develops a reddish color tone, are contained in one thermosensitive coloring layer, and ( 3) The first dye precursor does not have an absorption peak in the near infrared region with 100 parts by weight of the dye precursor that develops a black color tone.
Dye precursor 10 to 200-fold coloring in shades of green to bluish have
The amount unit and multicolor heat-sensitive recording material which comprises a mixture of a dye precursor 10 to 200 parts by weight having a strong absorption peak in colored shades of green to bluish, and near-infrared region. 3. The first dye precursor comprises 100 parts by weight of 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane and 10-200 parts by weight of 3- (4-diethylamino). 2-Ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide and 10-200 parts by weight of 3,3 -bis (4-diethylamino-2-ethoxyphenyl). A multicolor thermosensitive recording material according to claims 1 and 2, which comprises a mixture with -4-azaphthalide.