JP2000079766A - Thermal recording material - Google Patents

Abstract

(57) [Summary] [Problem] Due to the difference in heating application conditions from a thermal head, the color develops into multiple colors having different color tones, the color tone of low-temperature printing is less mixed at the time of high-temperature coloring, and the background fog is reduced. To provide a less multicolor heat-sensitive recording material. SOLUTION: A heat-sensitive coloring layer or a support, formed thereon, containing at least one dye precursor, and a color developing compound which reacts with the dye precursor under heating to form a color therefrom, or A multicolor thermosensitive coloring layer, and 55
After storage for 100 hours in an environment of 90 ° C. and 90% RH, the whiteness of the non-image portion is 70% or more. 3-diethylamino-7 as the dye precursor
Selected from -chlorofluorane, 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide, and 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluoran It is preferable that the color developing compound is 2,4-di (benzenesulfonyl) phenol.

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 more particularly to a heat-sensitive recording material having excellent storage stability of an image and having less coloration in a non-image portion (hereinafter referred to as background fog). Also, the present invention develops multiple colors having different color tones due to differences in heating application conditions from the thermal head,
The present invention relates to a multicolor heat-sensitive recording material that has low color mixing in low-temperature printing and low color mixing during high-temperature coloring and low background fog.

[0002]

2. Description of the Related Art Conventionally, a dye precursor and a color developing reaction between the dye precursor and a color developer which is brought into contact with the developer under heating to form a color are utilized.
Thermal recording materials for obtaining a color image are widely known. Such heat-sensitive recording materials are relatively inexpensive,
Because the recording equipment is compact and easy to maintain, facsimile, word processor, various computers,
And as a recording medium for other uses.

With respect to the heat-sensitive recording material, the required quality has been diversified with the expansion of uses thereof. For example, there have been demands for high sensitivity, image stabilization, multicolor recording, and the like.

[0004] The conventional heat-sensitive recording material has a drawback that the colored portion after printing is erased by oil or a plasticizer. For the purpose of preventing this, various proposals have been made so far. For example, a method of improving the storage stability by microencapsulating a coloring component as a core substance is disclosed in Japanese Patent Application Laid-Open No. 57-12695. And JP-A-59-21469
No. 1 and the like. Japanese Patent Application Laid-Open No. 9-262
JP-A-457-457, JP-A-9-263057, and JP-A-9-290565 disclose methods for improving image stability by compounding a color-forming component and a polymer compound.

However, even if these means are used,
Depending on the selection of the color-developing compound, sufficient image stability may not be obtained, and the background of the heat-sensitive recording material may be colored to reduce whiteness, that is, so-called fog may be a problem.

[0006] The multicolor recording means has the advantage that characters or graphics to be emphasized can be clearly and clearly displayed in a different color tone from other parts. Among them, a two-color heat-sensitive recording material capable of recording in two colors of red and black is excellent in versatility, and therefore demand for practical use is high.

As a multicolor heat-sensitive recording system, attempts have been made to utilize a difference in heating temperature or a difference in heat energy, and various multicolor heat-sensitive recording materials have been proposed. In general, a multicolor heat-sensitive recording material is formed by sequentially laminating a high-temperature coloring layer and a low-temperature coloring layer that develop different colors on a support. There are two types of molds.

Examples of the decolorizable multicolor heat-sensitive recording material include, for example, JP-A-50-17865 and JP-A-57-14.
As disclosed in Japanese Patent Publication No. 320 and JP-A-2-80287, only the low-temperature coloring layer is colored by the low-temperature coloring operation. This is a method in which a decoloring agent having an action acts to obtain color development only in the high-temperature coloring layer. This method has an advantage that the color tone can be freely selected, but it is necessary to add a large amount of a decoloring agent in order to obtain a sufficient decoloring effect on the low-temperature coloring layer. However, due to the action of a large amount of the decolorizing agent, the recorded color-developed image fades during long-term storage, or an excessive amount of heat is required to melt the decoloring agent, which places an excessive burden on the thermal head. However, it is not always satisfactory in terms of the reliability of the recorded image, the recording sensitivity, and the like.

On the other hand, a color-added multicolor heat-sensitive recording material is
JP-B-49-27708, JP-B-51-1998
No. 9, JP-A-51-146239, and the like, a method of laminating two color-forming layers that develop different colors and applying two different amounts of heat to obtain two colors that can be identified. is there. In this method, the lower color layer is black because the upper color layer develops color at low temperature to obtain the upper color tone, and the upper and lower color layers develop color at high temperature, and an image with a mixed color tone of both colors is obtained. It is suitable for coloring. Since no color erasing agent is used in an additive color recording material, there is an advantage that compared with a color erasure type recording material, the recorded image has excellent long-term storage properties and can be manufactured relatively inexpensively. Also, since no extra heat is required for melting the decoloring agent, there is an advantage that the high-temperature coloring layer can be colored with lower energy than the decoloring type. However, in the color-added multicolor heat-sensitive recording material having such a configuration, if too much heat is applied at the time of low-temperature coloring, color mixing occurs because a part of the coloring of the high-temperature coloring layer is also mixed, and it is difficult for a low-temperature coloring image to be sharp. There was a problem. In particular, depending on the selection of the color-developing compound, the division of the color-forming sensitivity may not be clear, the color separation may be insufficient, and only an indistinct multicolor may be obtained. Therefore, in order to obtain a multicolor heat-sensitive recording material having excellent color separation properties, selection of a color developing compound is an important point. See also
Japanese Patent Application Laid-Open No. 6-99697 describes a method in which two or more dye precursors having different color tones and different average particle diameters are mixed in the same layer, but the color mixing at low temperature coloring becomes more intense. There was a problem.

[0010] Japanese Patent Publication No. 4-4960 and Japanese Unexamined Patent Publication No.
JP-A-10-101885 describes that a color-forming component, which forms colors different from each other, is dissolved in a solvent, and each of the components is contained in two or more types of microcapsules having different glass transition temperatures to achieve multicoloring. . However, separately encapsulating two or more types of dye precursors that develop different color tones reduces the color development sensitivity of each of the two dye precursors, making it difficult to classify the sensitivity, and as a result, mixing of the color tones is likely to occur. There was a problem.

On the other hand, the color-forming dye is microencapsulated or formed into composite fine particles to lower the color-forming sensitivity, and the sensitivity is classified using the difference in color-forming sensitivity from the color-forming dye existing in the form of solid fine particles. Multicolor heat-sensitive recording materials are disclosed in JP-A-9-76634 and JP-A-9-1420.
No. 25 and JP-A-9-290565. However, even in a multicolor heat-sensitive recording material using a technique of microencapsulation or composite fine particle formation, depending on the selection of a color developing compound, there is a problem that the classification of color development sensitivity is not sufficient and color separation becomes unclear. Further, depending on the selection of the coloring dye, there are problems such as poor image stability and fogging of the background. Therefore, it has been demanded to obtain a multicolor heat-sensitive recording material having good color separation properties, excellent image stability, and low background fog.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-color image having different color tones due to a difference in heating application conditions from a thermal head. An object of the present invention is to provide a multicolor heat-sensitive recording material which has a small amount of background fogging.

[0013]

Means for Solving the Problems The heat-sensitive recording material according to the present invention is formed on a support, on which at least one dye precursor, and reacts with the dye precursor under heating to form And a heat-sensitive coloring layer containing a color developing compound for coloring
After storing for 0 hours, the whiteness of the non-image portion based on JIS P8123 is 70% or more.

The thermosensitive coloring layer in the present invention is obtained by emulsifying and dispersing a solution containing a polyisocyanate compound as a solvent and a dye precursor as a solute in water, and then promoting the polymerization reaction of the polyvalent isocyanate compound. It is preferable to contain the obtained composite fine particles.

It is preferable that the thermosensitive coloring layer in the present invention contains microcapsules containing a polymer compound as a wall material, a high boiling point solvent as a solvent, and a solution containing a dye precursor as a solute as a core substance.

Further, the dye precursor according to the present invention comprises:
3-diethylamino-7-chlorofluoran, 3,3
'-Bis (1-n-butyl-2-methylindole-3
-Yl) phthalide and at least one member selected from 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluoran.

The heat-sensitive recording material according to the present invention comprises: a support;
2 formed thereon and developing colors different from each other
A multicolor thermosensitive coloring layer containing at least one kind of dye precursor and a color developing compound which reacts with the dye precursor under heating to develop the color, and has a temperature of 55 ° C. and 90% RH. JIS P812 after storing for 100 hours in the environment of
The whiteness based on No. 3 is 70% or more.

The multicolor thermosensitive coloring layer according to the present invention comprises:
(1) composite fine particles obtained by emulsifying and dispersing a solution containing a first dye precursor as a solute in water and using a polyvalent isocyanate compound as a solvent, and then promoting the polymerization reaction of the polyvalent isocyanate compound; And 2) solid fine particles comprising a second dye precursor that develops a color tone different from the first dye precursor.

Further, the multicolor thermosensitive coloring layer in the present invention comprises: (1) a micro-layer containing a polymer compound as a wall material, a high-boiling-point solvent as a solvent, and a solution containing a first dye precursor as a solute as a core substance. It is preferable to contain a capsule and (2) solid fine particles made of a second dye precursor that develops a color tone different from the first dye precursor.

Further, in the present invention, the second dye precursor is 3-diethylamino-7-chlorofluoran, 3,
3'-bis (1-n-butyl-2-methylindole-
It is preferably at least one selected from 3-yl) phthalide and 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluoran.

In the present invention, the color-developing compound is 2,2.
Particularly preferred is 4-di (benzenesulfonyl) phenol.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the heat-sensitive recording material of the present invention, (1) solid fine particles of a first dye precursor and (2) a color-developing compound which is brought into contact with a dye precursor under heating to form a color. , 2,4-di (benzenesulfonyl) phenol, and (3) 3-diethylamino-7-chlorofluorane, 3,3'-bis (1-n-butyl-2-methylindole-) as a second dye precursor. 3-yl) phthalide, 3
A heat-sensitive recording layer containing at least one selected from-(N-ethyl-N-isoamylamino) -7-phenoxyfluoran is provided on a sheet-like support.

In the multicolor heat-sensitive recording material of the present invention, (1) a solution containing a polyvalent isocyanate compound as a solvent and a first dye precursor as a solute is emulsified and dispersed in water, and then the polyvalent isocyanate compound is polymerized. A composite microparticle obtained by accelerating the reaction, or a microcapsule containing a polymer compound as a wall material, a solution containing a high boiling point solvent as a solvent, and a first dye precursor as a solute as a core substance, and (2) 2) diphenylbenzene sulfonylphenol as a color developing compound which develops a color by contacting it with a dye precursor under heating;
-Diethylamino-7-chlorofluoran, 3,3'-
Multicolor containing at least one selected from bis (1-n-butyl-2-methylindol-3-yl) phthalide and 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluoran The heat-sensitive recording layer is provided on a sheet-like support.

In the multicolor heat-sensitive recording material of the present invention, (1) a solution containing a polyvalent isocyanate compound as a solvent and a first dye precursor as a solute is emulsified and dispersed in water, and then the polyvalent isocyanate compound is polymerized. A composite microparticle obtained by accelerating the reaction, or a microcapsule containing a polymer compound as a wall material, a solution containing a high boiling point solvent as a solvent, and a first dye precursor as a solute as a core substance, and (2) 2) diphenylbenzene sulfonylphenol as a color-developing compound capable of forming a color by contacting the dye precursor under heating, and (3) at least 3-diethylamino-7-chloroform as a second dye precursor. A combination of fluoran and 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide in a weight ratio of 1:20 to 20: 1. A.

The color-developing compound that can be used in the heat-sensitive recording material is selected from those having a property of liquefying or dissolving by an increase in temperature, and a property of contacting with a dye precursor to develop a color. Typical examples include phenolic compounds, aromatic carboxylic acids, and organic acidic substances such as salts of these compounds with polyvalent metals. Among these color developing compounds,
2,4-di (benzenesulfonyl) phenol is obtained by emulsifying and dispersing a solution containing a polyisocyanate compound as a solvent and a dye precursor as a solute in water, and then promoting the polymerization reaction of the polyvalent isocyanate compound. The heat-sensitive coloring image obtained by combining with a coloring material such as a microcapsule containing a composite fine particle or a polymer compound as a wall material, a solution containing a high boiling point solvent as a solvent, and a dye precursor as a solute as a core substance, as a core substance. The storage stability was found to be excellent. Further, since the color development of 2,4-di (benzenesulfonyl) phenol and the dye precursor rises sharply at a certain temperature, when applied to multicolor thermal recording, the first color development at a low temperature and the second color development at a high temperature It has the feature that the boundary with color formation is clear, that is, there is no color mixing and the color separation is excellent. In particular, in the color development with the dye precursor contained in the composite fine particles or microcapsules,
This tendency is strong, and the clarity of color separation is outstanding. These multicolor heat-sensitive recording materials may have a configuration of a multilayer coloring layer in which a plurality of dye precursors are respectively arranged in different layers, or a single-layer coloring layer in which a plurality of dye precursors are contained in the same layer. There may be.

Usually, the color-developing compound is preferably used in an amount of 30 to 2,000 parts by weight, more preferably 100 parts by weight, based on 100 parts by weight of the coloring dye present in the composite fine particles, the microcapsules and in the solid fine particle state. Is 50-2
It is used in a proportion of 00 parts by weight.

If necessary, in addition to 2,4-di (benzenesulfonyl) phenol, the following color developing compounds generally used in heat-sensitive recording materials may be used in combination. it can. Representative color developing compounds include 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol,
4'-sec-butylidenediphenol, 4-phenylphenol, 4,4'-dihydroxydiphenylmethane, 4,4'-isopropylidenediphenol, 4,
4'-dihydroxydiphenyl ether, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone,
4,4'-cyclohexylidenediphenol, 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, 4-
Phenolic compounds such as hydroxy-4'-isopropoxydiphenyl sulfone and bis (3-allyl-4-hydroxyphenyl) sulfone can be mentioned.

Further, in the present invention, compounds that can be used as a color developing compound include 4-hydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, and 4-hydroxybenzoic acid. Phenolic compounds such as -sec-butyl, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenyl ether, or benzoic acid; p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3,5-di- Aromatic carboxylic acids such as ert- butyl salicylate, further can be cited such as zinc, magnesium, aluminum, and organic acidic substances such as aromatic carboxylic acid salt is a salt with a polyvalent metal such as calcium.

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

The color precursor of the dye precursor contained in the composite fine particles has extremely good preservability, particularly excellent resistance to oils and plasticizers, as compared with the color former colored in the form of solid fine particles. . Although the reason is not always clear, it is considered that the color former and the polymer substance (base material) have an interaction and are stabilized.

The external appearance of the composite fine particles used in the present invention is substantially spherical or slightly dented erythrocyte when observed with an electron microscope. In cross-sectional observation with an electron microscope, the shape is an internal body, a porous body, or a hollow body. When applied to a single-color heat-sensitive recording material, the average particle size is desirably 0.2 to 1.5 μm in order to obtain an appropriate color sensitivity. When the particle size is small, the storage stability of the colored portion with respect to oil, plasticizer and the like may be deteriorated, and it is not desirable to make the average particle size smaller than 0.2 μm. When applied to a multicolor heat-sensitive recording material, the average particle diameter is desirably 0.5 to 5.0 µm. When the average particle size is smaller than 0.5 μm, it is difficult to distinguish the color developing sensitivity from the dye precursor in the form of solid fine particles having different color developing tones to be mixed, and color mixing may occur at low temperature. If the average particle size is larger than 5.0 μm, the coloring sensitivity is lowered, and it is necessary to excessively apply energy to the thermal head, which is not preferable.

The microcapsules enclosing the dye precursor used in the present invention are those in which a solution of the dye precursor is a core material as a liquid part, which is protected by the capsule wall material. It is clearly distinguished from the shell. Therefore, the 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 be present in a solid solution state with the polymer.

In the multicolor heat-sensitive recording material of the present invention, the compound which can be used as the first dye precursor contained in the composite fine particles and microcapsules or as the second dye precursor existing in the form of solid fine particles is , Triaryl, diphenylmethane, thiazine, spiro, lactam, and fluoran leuco compounds can be preferably used. Such a dye precursor gives a unique color tone upon contact with a color developer, and the color tone ranges from black, red, magenta, orange, blue, green, and yellow.

Among the second dye precursors which are present as solid fine particles, mention is made in particular of 3-diethylamino-7-chlorofluoran, 3,3'-bis (1-n-butyl-2-methylindol-3-yl) ) Phthalide, and 3- (N
-Ethyl-N-isoamylamino) -7-phenoxyfluoran, when the multicolor heat-sensitive recording material of the present invention is used, the color development sensitivity at a predetermined temperature is high, and the first color development at a low temperature is obtained. The boundary with the second color development at high temperature is clear, there is no color mixing, and clear color separation is obtained,
Further, there is little fogging of the background, and the obtained image has excellent stability. The second dye precursor is 3-diethylamino-7
Selected from -chlorofluorane, 3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide, and 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluoran At least one of these compounds can be used as a single compound, but in particular 3-diethylamino-
It is preferable to use 7-chlorofluorane and 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide in combination in a weight ratio of 1:20 to 20: 1. Further, one or more other different color-forming dye precursors can be mixed for the purpose of obtaining a desired color tone.

In the case of the multicolor heat-sensitive recording material of the present invention,
The low-temperature color tone is the color tone of the second dye precursor present in the state of solid fine particles, and the high-temperature color tone is a color mixture of the first dye precursor present in the composite fine particles. In the multicolor heat-sensitive recording material, in order to emphasize the difference between the high-temperature color tone and the low-temperature color tone, a color-forming dye having a color tone different from the low-temperature color tone, more preferably a complementary color-forming dye, is used. (1) It is preferable that the dye is contained in the composite fine particles together with the dye precursor. For example, as the specific second dye precursor present in the form of solid fine particles in the present invention, 3-diethylamino-7-chlorofluorane and 3,3′-bis (1-n-butyl-2-methylindole-3- Ill)
In a multicolor heat-sensitive recording material using phthalide in combination, the low-temperature color tone is reddish. When the high-temperature coloring tone is a black color, a black coloring dye precursor is used as the first dye precursor in the composite fine particles, and a dye precursor that develops a blue or green color that is a complementary color to the red color is used. The difference between the low-temperature color tone and the high-temperature color tone can be made more prominent by including the black color-forming first dye precursor in the composite fine particles. Of course, as the first dye precursor, a dye precursor having various color tones may be contained in addition to the black and blue to green dye precursors to correct the color tone.

Further, the color-forming first dye precursor contained in the composite fine particles or microcapsules or the second dye precursor existing in the form of solid fine particles contains a color-forming dye having strong absorption in the near infrared region. This makes it possible to provide a thermosensitive recording material having excellent readability in an optical character reader or a barcode reader.

In the multicolor heat-sensitive recording material of the present invention, as the first dye precursor contained in the composite fine particles and the second dye precursor existing in the form of solid fine particles, one or more of the following compounds can be used.

As a dye precursor giving a black color, 3-
Pyrrolidino-6-methyl-7-anilinofluoran, 3
-Diethylamino-7- (m-trifluoromethylanilino) fluoran, 3-diethylamino-6-methyl-
7- (m-methylanilino) fluoran, 3- (N-isoamyl-N-ethylamino) -7- (o-chloroanilino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-ani Linofluoran, 3- (N
-Ethyl-N-2-tetrahydrofurfurylamino)-
6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-di-
n-butylamino-6-methyl-7-anilinofluoran, 3-di-n-amylamino-6-methyl-7-anilinofluoran, 3- (N-isoamyl-N-ethylamino) -6 Methyl-7-anilinofluoran, 3-
(Nn-hexyl-N-ethylamino) -6-methyl-7-anilinofluoran, 3- [N- (3-ethoxypropyl) -N-ethylamino] -6-methyl-7-anilino Fluoran, 3- [N- (3-ethoxypropyl) -N-methylamino] -6-methyl-7-anilinofluoran, 3-diethylamino-7- (2-chloroanilino) fluoran, 3-di-n -Butylamino-7-
(2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (2,6-dimethylanilino) fluoran, 3-diethylamino-6-methyl -7
-(2,4-dimethylanilino) fluoran, 2,4-
Examples thereof include dimethyl-6- (4-dimethylaminoanilino) fluoran and 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluoran.

Among the dye precursors giving a black color, 3-di-n-amylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7, which are relatively excellent in light resistance. -(2,6-dimethylanilino) fluoran, 3-diethylamino-6-methyl-7
-(2,4-dimethylanilino) fluoran, 2,4-
It is preferably at least one selected from dimethyl-6- (4-dimethylaminoanilino) fluoran.

The dye precursor giving a blue color includes:
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2)
-Methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylamino-2-methylphenyl) -4-azaphthalide, 3- (1-ethyl-2-methyl) Indole-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.

As the dye precursor giving green color, 3
-(N-ethyl-NN-hexylamino) -7-anilinofluoran, 3-diethylamino-7-dibenzylaminofluoran, 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4 -Azaphthalide, 3-
(N-ethyl-Np-tolylamino) -7- (N-phenyl-N-methylamino) fluoran, 3- [p-
(P-anilinoanilino) anilino] -6-methyl-7
-Chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, and the like.

Dye precursors having absorption in the near infrared region include 3,3'-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 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-chlorofluoran, 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) pyridofluoran, 3-di (n-butyl) amino-6,8,8-trimethyl-8,9-dihydro-
(3,2, e) pyridfluoran, 3- [1,1-bis (p-diethylaminophenyl) ethylene-2-yl]
-6-dimethylaminophthalide, 3- (pn-butylaminoanilino) -6-methyl-7-chlorofluorane, 2-mesidino-8-diethylamino-benz [C]
And fluoran.

Dye precursors that develop a red color that can be used in the present invention include 3,6-bis (diethylamino) fluoran-γ-anilinolactam and 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-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-ethylfluorane, 3- (N-ethyl-N-isobutylamino) -6-methyl-7 -Chlorofluorane, and 3-
(N-ethyl-N-isoamylamino) -7,8-benzofluoran and the like.

Further, 3-cyclohexylamino-6-chlorofluorane, 3-di-n-butylamino-6-methyl-7-bromofluorane, 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, and 2- (N-methylanilino) -3-methyl-
Examples thereof include 6-di-n-butylaminofluoran and 3-diethylamino-7-phenoxyfluoran.

Further, 3,3'-bis (1-ethyl-
2-methylindol-3-yl) phthalide, 3,3 '
-Bis (1-n-octyl-2-methylindole-3
-Yl) phthalide, 7- (N-ethyl-N-isoamylamino) -3-methyl-1-phenylspiro [(1,4
-Dihydrochromeno [2,3-c] pyrazole) -4,
3'-phthalide], 7- (N-ethyl-N-isoamylamino) -3-methyl-1-p-methylphenylspiro [(1,4-dihydrochromeno [2,3-c] pyrazole) -4 , 3'-phthalide], and 7- (N-ethyl-Nn-hexylamino) -3-methyl-1-phenylspiro [(1,4-dihydrochromeno [2,3-c]
Pyrazole) -4,3'-phthalide] and the like as red dye precursors.

Dye precursors which give yellowish color development include 3,6-dimethoxyfluoran and 1- (4-
n-dodecyloxy-3-methoxyphenyl) -2-
(2-quinolyl) ethylene and the like.

In the production of the composite fine particles used in the present invention, the method described in JP-A-9-295457 can be used.

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

The microcapsules used in the present invention can be prepared by various known methods such as the method described in JP-A-59-214691, and generally, the above-mentioned dye precursor is optionally added to an organic solvent if necessary. Is prepared by emulsifying and dispersing a core substance (oil-based liquid) obtained by dissolving the polymer in an aqueous medium to form a wall film made of a polymer substance around the oil-based droplets. Specific examples of the polymer substance serving as the wall film of the microcapsule include, for example, polyurethane resin, polyurea resin,
Examples include polyamide resin, polyester resin, polycarbonate resin, aminoaldehyde resin, melamine resin, polystyrene resin, styrene-methacrylate copolymer resin, styrene-acrylate resin, gelatin, and polyvinyl alcohol. Among them, microcapsules having a wall film made of polyurethane-polyurea resin or aminoaldehyde resin are particularly preferably used because of their excellent heat resistance.

In the present invention, when a multicolor heat-sensitive recording material is used, a second dye precursor that develops a color tone different from that of the first dye precursor contained in the composite fine particles or microcapsules is used in the form of solid fine particles. In this case, the second dye precursor is pulverized by various wet pulverizers such as a sand grinder, an attritor, a ball mill, and a cobo mill using water as a dispersion medium, and this is modified with polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, and a sulfone group. Water-soluble polymer compounds such as modified polyvinyl alcohol such as polyvinyl alcohol, methylcellulose, carboxymethylcellulose, styrene-maleic anhydride copolymer salts and derivatives thereof, and, if necessary, dispersed together with a surfactant and an antifoaming agent The dispersion liquid is dispersed in a medium, and this dispersion liquid can be used for preparing a thermosensitive coloring layer or a multicolor thermosensitive coloring layer-forming coating material. After dissolving the dye precursor in an organic solvent, this solution is emulsified and dispersed in water using the water-soluble polymer as a stabilizer, and the organic solvent is evaporated from the emulsion to form the dye precursor into solid fine particles. You can also. In each case, the average particle size of the dispersed particles of the dye precursor used in the state of solid fine particles is 0.2 to 3.0 in order to obtain appropriate color sensitivity.
μm, more preferably 0.3 to
1.5 μm. Of course, a dye precursor having the same color tone can be used in the form of solid fine particles together with the composite fine particles to obtain a single-color heat-sensitive recording material.

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

In the present invention, a sensitizer can be used to improve the heat-sensitive recording color development sensitivity. As the sensitizer that can be used, a compound conventionally known as a sensitizer for a heat-sensitive recording material can be used, for example, parabenzylbiphenyl, dibenzylterephthalate,
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-chlorobenzyl oxalate, 1,2-bis (3,4
-Dimethylphenyl) ethane, 1,3-bis (2-naphthoxy) propane, meta-terphenyl, diphenyl,
Benzophenone and the like can be given. Among these compounds, it is preferable to use di-p-methylbenzyl oxalate and di-p-chlorobenzyl oxalate as sensitizers because a sensitizing effect with less fog can be obtained.

Additives such as the color-developing compound, image stabilizer and 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, and the heat-sensitive coloring layer Alternatively, it may be mixed with a coating material for forming a multicolor thermosensitive coloring layer. Further, these additives may be dissolved in a solvent and emulsified in water using a water-soluble polymer compound as an emulsifier. Further, the image stabilizer and the sensitizer may be contained in the composite fine particles containing the dye precursor.

In the present invention, a fine pigment having a high whiteness and an average particle diameter of 10 μm or less is added to the heat-sensitive coloring layer or the multicolor heat-sensitive coloring layer to improve the whiteness of the heat-sensitive coloring layer or the multicolor heat-sensitive coloring layer. It can be contained in a multicolor 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, inorganic pigments such as silica, urea-formalin resin, styrene-methacrylic acid copolymer resin, polystyrene Organic pigments such as resins can be used. It is preferable to use a pigment having an oil absorption of 50 ml / 100 g or more in order to prevent sticking of the residue to the thermal head and prevention of sticking. The amount of the pigment
It is preferable that the amount does not lower the coloring density, that is, 50% by weight or less based on the total solid weight of the thermosensitive coloring layer or the multicolor thermosensitive coloring layer.

In the present invention, an adhesive is used as another component material constituting the thermosensitive coloring layer or the multicolor thermosensitive coloring layer, and if necessary, a crosslinking agent, a wax, a metal soap, a colored dye, a colored pigment and a fluorescent material. Dyes and the like can be used. As the adhesive, those similar to those used in the undercoat layer, for example, polyvinyl alcohol and derivatives thereof, starch and derivatives thereof, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose derivatives such as ethyl cellulose, polyacrylic acid Soda, polyvinylpyrrolidone, acrylamide-acrylate copolymer, acrylamide-acrylate-methacrylate copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin and Water-soluble polymer materials such as derivatives thereof, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl Methacrylate, ethylene - vinyl acetate copolymer emulsion and styrene -
Latexes of water-insoluble polymers such as butadiene copolymers and styrene-butadiene-acrylic copolymers can be mentioned.

In order to improve the water resistance of the thermosensitive coloring layer or the multicolor thermosensitive coloring layer, a crosslinking agent for three-dimensionally curing the adhesive may be contained in the thermosensitive coloring layer or the multicolor thermosensitive coloring layer. it can. For example, aldehyde compounds such as glyoxal, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, dimethylol urea compounds, aziridine compounds,
Blocked isocyanate compounds, and at least one selected from inorganic compounds such as ammonium persulfate, ferric chloride, magnesium chloride, sodium tetraborate, potassium tetraborate, or boric acid, boric acid triesters, boron-based polymers, and the like. It is preferable to use the crosslinkable compound in the range of 1 to 10 parts by weight based on 100 parts by weight of the total solid content of the thermosensitive coloring layer or the multicolor thermosensitive coloring layer.

Examples of the wax added to the thermosensitive coloring layer or the multicolor thermosensitive coloring layer include waxes such as paraffin wax, carnauba wax, microcrystalline wax, polyolefin wax and polyethylene wax, and, for example, stearic acid amide, ethylene bisstearic acid Examples thereof include higher fatty acid amides such as amides, higher fatty acid esters and derivatives thereof. In particular, when a methylolated fatty acid amide is added to the heat-sensitive color-forming layer or the multicolor heat-sensitive color-forming layer, the sensitizing effect can be obtained without deteriorating the background fog, so that it can be preferably used.

Examples of the metal soap added to the thermosensitive coloring layer or the multicolor thermosensitive coloring layer include 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 a two-color heat-sensitive recording material, it is possible to include a colored dye and / or a colored pigment having a color tone complementary to the low-temperature color tone in the multicolor thermosensitive coloring layer. It is preferably used for adjusting the color tone of a recording material before printing. If necessary,
Various additives such as an oil repellent, an antifoaming agent, and a viscosity modifier can be further added to the thermosensitive coloring layer or the multicolor thermosensitive coloring layer as long as the effects of the present invention are not impaired.

In the present invention, the heat-sensitive coloring layer or the multicolor heat-sensitive coloring layer has a coating amount of 2 to 20 g / d on the undercoat layer after drying.
m ² , more preferably 4 to 10 g / m ² .

In the present invention, microcapsules containing an ultraviolet absorbent or solid fine particles of the ultraviolet absorbent are contained in the heat-sensitive coloring layer, the multicolor heat-sensitive coloring layer, or the protective layer provided thereon. Thus, light resistance can be significantly improved.

Specific examples of the ultraviolet absorber include the following. Phenyl salicylate, pt
salicylic acid ultraviolet absorbers such as tert-butylphenyl salicylate and p-octylphenyl salicylate;
2,4-dihydroxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-
Benzophenone-based ultraviolet absorbers such as dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 2-hydroxy-4-methoxy-5sulfobenzophenone; I can give it.

Further, 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-
Yl) -4-hydroxyphenyl] propionate and other benzotriazole ultraviolet absorbers, such as 2′-
Examples include cyanoacrylate-based ultraviolet absorbers such as ethylhexyl-2-cyano-3,3-diphenylacrylate and ethyl-2-cyano-3,3-diphenylacrylate. Of course, the present invention is not limited to these, and two or more kinds can be used in combination as needed.

Among these ultraviolet absorbers, benzotriazole-based 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 is particularly preferable because it exhibits a particularly remarkable effect of improving light resistance.

The amount of the microcapsules containing the ultraviolet absorber or the solid fine particles of the ultraviolet absorber is not particularly limited, but may be contained in the heat-sensitive coloring layer or the multicolor heat-sensitive coloring layer, or may be added to the heat-sensitive coloring layer. When contained in the protective layer provided on the layer or on the multicolor thermosensitive coloring layer, in any case, 5 to 5% of the total solid content of each layer.
About 70% by weight is preferable. Particularly preferably, 15 to 50
% By weight. When the amount is less than 5% by weight, the effect of improving light resistance is poor. When the amount is more than 70% by weight, the effect of improving light resistance is not only saturated, but also the color sensitivity of the thermosensitive coloring layer or the multicolor thermosensitive coloring layer is reduced. Sometimes.
Microcapsules containing UV absorbers or solid fine particles of UV absorbers contained in the protective layer more effectively improve light resistance than contained in the thermosensitive coloring layer or multicolor thermosensitive coloring layer. Can be.

The microcapsules of the ultraviolet absorbent used in the present invention can be prepared by various known methods. In general, the solid or liquid ultraviolet absorbent at room temperature is dissolved in an organic solvent as required. The obtained core substance (oil-based liquid) is emulsified and dispersed in an aqueous medium, and is prepared by a method of forming a wall film made of a polymer substance around oil-based droplets. As a specific example of the polymer substance which becomes the wall film of the microcapsule,
For example, polyurethane resin, polyurea resin, polyamide resin, polyester resin, polycarbonate resin, aminoaldehyde resin, melamine resin, polystyrene resin,
Styrene-methacrylate copolymer resin, styrene-acrylate resin, gelatin, polyvinyl alcohol and the like can be mentioned. Among these, in particular, microcapsules having a wall film made of a polyurethane-polyurea resin or an aminoaldehyde resin are excellent in heat resistance. Therefore, in order to prevent sticking to a thermal head, the microcapsules are used in a thermosensitive coloring layer or in a multicolor thermosensitive coloring. In the layer or in the protective layer, it has an excellent accompanying effect of also functioning as an inorganic pigment added to the protective layer, and has a lower refractive index than microcapsules made of other wall films and ordinary pigments, and Since it is spherical in shape, even if it is added in a large amount in the protective layer, there is no possibility of causing a decrease in density due to irregular reflection of light, so that it is preferably used.

The microcapsules enclosing the ultraviolet absorbent used in the present invention are those in which the ultraviolet absorbent is a core substance as a liquid part, is protected by the capsule wall material, and the dye precursor is high. Composite particles containing a molecule and a dye precursor which is considered to exist in a solid solution state are completely different in the state of existence, shape, and desired function.

In the present invention, the addition of a fluorescent whitening agent to the thermosensitive coloring layer, the multicolor thermosensitive coloring layer, or the protective layer also has an effect of improving light resistance and can be preferably used. Fluorescent whitening agents are widely used as whitening agents because they have the function of absorbing light in the ultraviolet region and emitting light in the visible light region having a longer wavelength. The dye precursor contained in the composite fine particles used in the present invention is decomposed by light in a high-energy ultraviolet region and has a property of easily yellowing, but a long-wavelength region in which ultraviolet light is more harmless by a fluorescent whitening agent. By changing to light of not only yellowing can be prevented, but also an effect on whiteness can be obtained. Also, decoloring of the printed portion by light can be improved by including a fluorescent whitening agent.

The fluorescent whitening agents usable in the present invention include:
Examples include pyrene, coumarin, oxazole, imidazole, imidazolone, pyrazole, benzidine, diaminocarbazole, naphthalic acid, and derivatives of diaminostilbene disulfonic acid. More specifically, 1,2-bis (5-methyloxazole-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-sodiumoxy And sulfonylphenyl ethylene. Among these compounds, diaminostilbene disulfonic acid derivative 1,2-bis {4- [2-
(P-sodiumoxysulfonylanilino) -4-bis (2-hydroxyethyl) amino-1,3,5-triazin-6-yl] amino-2-sodiumoxysulfonylphenyl {ethylene} coating liquid preparation It is preferable from the viewpoint of easy handling at the time.

The amount of the fluorescent whitening agent to be added is not particularly limited, but is preferably about 0.5 to 15% by weight, more preferably about 0.5 to 15% by weight, based on the total solid content of the thermosensitive coloring layer or the multicolor thermosensitive coloring layer. Ranges from 1 to 10% by weight.
When the amount is less than 0.5% by weight, a sufficient fluorescent whitening effect cannot be obtained, and when the amount is more than 10% by weight, the background is colored by the color of the fluorescent brightening agent itself, resulting in a heat-sensitive recording material having a poor natural paper feeling. Therefore, it is not preferable.

In the present invention, the magnetic recording layer is provided on the surface of the support on which the thermosensitive coloring layer or the multicolor thermosensitive coloring layer is not provided, or between the support and the thermosensitive coloring layer or the multicolor thermosensitive coloring layer. It can also be provided. As the magnetic recording layer, a magnetic recording layer conventionally used for a magnetic ticket, a prepaid card, a magnetic commuter pass, or the like can be used. The magnetic recording layer is, of course, provided between the support and the heat-sensitive coloring layer or the multi-color heat-sensitive coloring layer, or in the case where the magnetic recording layer is provided on the surface where the heat-sensitive coloring layer or the multi-color heat-sensitive coloring layer is not provided. Also, it is desirable to apply the coating before providing the thermosensitive coloring layer or the multicolor thermosensitive coloring layer in order to keep the whiteness of the thermosensitive coloring layer or the multicolor thermosensitive coloring layer high.

In the present invention, an undercoat layer used in a conventionally known heat-sensitive recording material can also be used. In particular, when paper is used as the 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 sensitivity of the thermosensitive coloring layer or the multicolor thermosensitive coloring layer can be increased. Including plastic pigments, hollow particles, foams, and the like in the undercoat layer is also effective in improving the color sensitivity of the heat-sensitive coloring layer or the multicolor heat-sensitive coloring 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 a conventionally known thermosensitive recording material on a thermosensitive coloring layer or a multicolor thermosensitive coloring layer. . As the water-soluble polymer material and the pigment, the materials exemplified for the thermosensitive coloring layer or the multicolor 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 coloring layer or the multicolor thermosensitive coloring layer so that the coating amount after drying is 0.5 to 10 g / m ² , more preferably 1 to 5 g. /
for coating such that m ^2.

In the present invention, a resin layer cured by an electron beam or ultraviolet rays may be provided on a thermosensitive coloring layer, a multicolor thermosensitive coloring layer, or a protective layer. Examples of the resin cured by an electron beam are described in JP-A-58-177392 and JP-A-58-177392. In such a resin, a non-electron beam curing resin, a pigment, an antifoaming agent,
Additives such as a leveling agent, a lubricant, a surfactant, and a plasticizer can be appropriately added. Especially calcium carbonate,
It is preferable to add a pigment such as aluminum hydroxide or a lubricant such as waxes or silicone because it helps prevent sticking to the thermal head. Resin layer cured with electron beam or ultraviolet light, curing and coating amount after drying is applied such that 0.5 to 10 g / m ^2, coating as more preferably a 1 to 5 g / m ² Work.

In the present invention, printing can be performed with UV ink, flexo ink, or the like. In this case, printing is performed on the thermosensitive coloring layer or on the multicolor thermosensitive coloring layer, on the protective layer,
Printing may be performed on any layer such as an electron beam curable resin layer or an 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 (acid paper, neutral paper), medium paper, coated paper, art paper, cast paper, etc. In addition to coated paper, glassine paper, resin-laminated paper, polyolefin-based synthetic paper, synthetic fiber paper, nonwoven fabric, synthetic resin film, and the like, various transparent supports and the like can be appropriately selected and used. When the present invention is used for magnetic ticket use, it is preferable to use paper. However, when the present invention is used for magnetic commuter pass use, a plastic base 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 coloring sensitivity. Of course, a laminated substrate of a foamed polyethylene terephthalate film and a non-foamed polyethylene terephthalate film can be used.

In the present invention, in order to increase the added value of the heat-sensitive recording material, the heat-sensitive recording material can be further processed to obtain a heat-sensitive recording material having a higher function. For example, by applying a pressure-sensitive adhesive, rewet adhesive, delayed tack type adhesive on the back surface, adhesive paper,
It can be rewet adhesive paper or delayed tack paper.
In particular, those that have been subjected to adhesive processing of the heat-sensitive recording material of the present invention,
It is useful as a heat-sensitive label because of its good storage stability. In addition, a recording material capable of performing double-sided recording can be provided by using the back surface of the recording material and imparting the function as thermal transfer paper, inkjet paper, carbonless paper, electrostatic recording paper, and xerographic paper. Of course, a double-sided heat-sensitive recording material can also be used.

The method for forming each of the above layers on the support may be any of known coating methods such as an air knife method, a blade method, a gravure method, a roll coater method, a spray method, a dipping method, a bar method and an extrusion method. May be used. In addition, a back layer can be provided to suppress penetration of oil or plasticizer from the back surface of the heat-sensitive 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 color sensitivity.
The surface of the heat-sensitive coloring layer or the surface of the multicolor heat-sensitive coloring layer may be treated by applying to either a metal roll or an elastic roll of a calender.

[0080]

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

<Preparation of Multicolor Thermosensitive Recording Material> Example 1 (1) Preparation of Materials Used for Undercoat Layer, Multicolor Thermosensitive Coloring Layer, and Protective Layer <Preparation of Black Fine Particle Precursor-Containing Composite Fine Particle Dispersion Solution> 8 parts of 3-di (n-amyl) amino-6-methyl-7-anilinofluoran as a black color-forming dye precursor at 100 ° C.
Dissolved in 24 parts of dicyclohexylmethane-4,4'-diisocyanate heated to 25 ° C., and after cooling this solution to 25 ° C., an aqueous solution of 8% polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gohsenol GM-14L) at the same temperature 250 parts of TK homomixer (Model H
VM, manufactured by Tokushu Kika Kogyo Co., Ltd.)
After emulsification and dispersion by stirring at pm, 100 parts of water was added to the emulsified dispersion to homogenize. This emulsified dispersion is
C., and a curing reaction was performed for 10 hours to prepare a dispersion of composite fine particles containing a chromogenic dye precursor having an average particle diameter of 1.1 μm.

<Preparation of Dye Precursor, Developing Compound, and Sensitizer Dispersion in Solid Fine Particle State> Red Developing Dye Precursor A: 3-Diethylamino-7-chlorofluorane Developing Compound: 2,4 -Di (benzenesulfonyl) phenol sensitizer: di-p-methylbenzyl oxalate

The red color-forming dye precursor A, the color-developing compound and the sensitizer are separately mixed with polyvinyl alcohol at the following compounding ratio, and each mixture is subjected to a vertical sand mill (manufactured by IMEX Co., Ltd., sand grinder). The resulting mixture was pulverized and dispersed so as to have an average particle diameter of 1.0 μm to obtain a dispersion of each compound in the form of solid fine particles.

Component Amount (parts by weight) Each compound 40 (dye precursor, color developing compound and sensitizer) Polyvinyl alcohol 10% solution 40 (polymerization degree 500, saponification degree 90%) water 20

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

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

(2) Formation of Undercoat Layer The above-mentioned pigment dispersion and adhesive liquid were mixed at a solid content of 8
0:20, and this paint was coated on a high-quality paper (neutral paper) with a basis weight of 60 g / m ² using a Meyer bar.
0.0 g / m ² (dry) was applied to form an undercoat layer.

(3) Formation of Multicolor Thermosensitive Color-Developing Layer The above-mentioned composite fine particles containing a black-coloring dye precursor, a red-coloring dye precursor A, a color-developing compound, a sensitizer, an inorganic pigment and an adhesive are 30: 7: 25: 15: 1
A Mayer bar was coated with the coating solution for a multicolor thermosensitive coloring layer, which was blended so as to be 5: 8, on the previously formed undercoat layer so that the coating amount (dry) was 8.0 g / m ^2. To form a multicolor thermosensitive coloring layer.

(4) Formation of protective layer A coating liquid for a protective layer was prepared by mixing the above-mentioned pigment dispersion, adhesive liquid and lubricant so that the solid content ratio was 40: 55: 5. 3.0 g / m3 on the formed thermosensitive coloring layer
Coating was performed using a Meyer bar so that the coating amount (drying) was ² to obtain a heat-sensitive recording material before smoothing treatment.

The heat-sensitive recording material thus obtained was subjected to a Beck smoothness (JIS) on the heat-sensitive recording surface using a super calendar.
P8119) to obtain a multicolor heat-sensitive recording material by performing a smoothing treatment so as to be 1200 to 1500 seconds.

Example 2 Red color-forming dye precursor B: 3- (N-ethyl-N-isoamylamino) together with the red color-forming dye precursor A
Using -7-phenoxyfluorane, composite particles containing a black coloring dye precursor, a red coloring dye precursor A, a red coloring dye precursor B, a color developing compound, a sensitizer, an inorganic pigment and an adhesive. , The solid content ratio is 30: 6: 1: 25: 1
A heat-sensitive recording material was produced in the same manner as in Example 1, except that the mixing ratio was 5: 15: 8.

Example 3 The red color-forming dye precursor B: 3,3'bis (1-n-
Example 2 except that the red chromogenic dye precursor C: 3- (N-ethyl-N-isoamylamino) -7-phenoxyfluorane was used in place of butyl-2-methylindol-3-yl) phthalide In the same manner as in the above, a heat-sensitive recording material was produced.

Example 4 A heat-sensitive recording material was prepared in the same manner as in Example 1, except that the black color-forming dye precursor-containing composite microparticles prepared in the following manner were used instead of the black color-forming dye precursor-containing composite fine particles. Produced. <Preparation of microcapsules encapsulating black chromogenic dye precursor> 8 parts of 3-di (n-amyl) amino-6-methyl-7-anilinofluoran as a black chromogenic dye precursor at 100 ° C.
After cooling to room temperature, 18 parts of tricresyl phosphate was heated and cooled to room temperature. Then, 6 parts of dicyclohexylmethane-4,4'-diisocyanate was added, and this solution was added to 8% polyvinyl alcohol (trade name: Gohsenol GM, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.). -14 L) The solution was gradually added to 250 parts of an aqueous solution, and emulsified and dispersed by stirring with a TK homomixer (Model HV-M, manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotation speed of 5000 rpm. And homogenized.
The temperature of the emulsified dispersion was raised to 80 ° C., and a curing reaction was performed for 10 hours to prepare a dispersion of microcapsules encapsulating a color-forming dye precursor having an average particle diameter of 1.2 μm.

Example 5 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that a multicolor heat-sensitive coloring layer was formed by the following method. Formation of multicolor thermosensitive coloring layer The following black coloring dye precursor, the color developing compound, sensitizer, inorganic pigment and adhesive used in Example 1 were mixed at a solid content of 7:25:15: A coating solution for a heat-sensitive coloring layer, which was blended at a ratio of 15: 8, was placed on the undercoat layer formed earlier.
Coating was performed using a Mayer bar so that the coating amount (drying) was 8.0 g / m ² , thereby forming a high-temperature thermosensitive coloring layer. Next, the red-color-forming dye precursor A, the color-developing compound, the sensitizer, the inorganic pigment, and the adhesive used in Example 1 were mixed at a solid content of 7: 25: 15: 15: 8. 4.0 g / m ² coating amount (dry) of the thermosensitive coloring layer coating liquid blended in
Was applied using a Meyer bar to obtain a low-temperature thermosensitive coloring layer. <Preparation of Black Chromogenic Dye Precursor Dispersion> 3-Di (n-amyl) amino-6-methyl-7-anilinofluorane was mixed with polyvinyl alcohol at the following mixing ratio, and each mixture was made into a vertical type. Using a sand mill (manufactured by Imex Co., Ltd., a sand grinder), the mixture was pulverized and dispersed so that the average particle diameter became 1.0 μm, to obtain a dispersion of each compound in a solid fine particle state.

Component Amount (parts by weight) Each compound 40 (the black coloring dye precursor, color developing compound and sensitizer) Polyvinyl alcohol 10% solution 40 (polymerization degree 500, saponification degree 90%) water 20

Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that 4,4'isopropylidenediphenol was used instead of the color developing compound 2,4-di (benzenesulfonyl) phenol.

Comparative Example 2 A heat-sensitive recording material was prepared in the same manner as in Example 3 except that 4,4'-isopropylidenediphenol was used instead of the color developing compound 2,4-di (benzenesulfonyl) phenol.

Comparative Example 3 A thermosensitive recording material was prepared in the same manner as in Example 4 except that 4,4'-isopropylidenediphenol was used instead of the color developing compound 2,4-di (benzenesulfonyl) phenol.

Example 5 A thermosensitive recording material was prepared in the same manner as in Example 5, except that 4,4'-isopropylidenediphenol was used instead of the color developing compound 2,4-di (benzenesulfonyl) phenol.

<Preparation of Single-Colored Thermosensitive Recording Material> Example 6 A thermosensitive recording material was prepared in the same manner as in Example 1 except that the red coloring dye precursor was not used.

Example 7 A heat-sensitive recording material was prepared in the same manner as in Example 4, except that the red color dye precursor was not used.

Comparative Example 4 A heat-sensitive recording material was prepared in the same manner as in Example 6, except that 4,4'-isopropylidenediphenol was used instead of the color developing compound 2,4-di (benzenesulfonyl) phenol.

Comparative Example 5 A heat-sensitive recording material was prepared in the same manner as in Example 7, except that 4,4′isopropylidenediphenol was used instead of the color developing compound 2,4-di (benzenesulfonyl) phenol.

<Evaluation of two-color heat-sensitive recording material>
Using the thermal printing tester TH-PMD (manufactured by Okura Electric Co., Ltd.) for the eight types of thermal recording materials of Comparative Examples 1 to 3, a one-line recording time: 5 msec, and a sub-scanning line density: 8
Line / mm, applied energy per dot: 0.5m
Solid printing of 256 lines was performed under the condition of J, and red coloring was recorded in low-temperature printing. Separately, under the conditions of 1-line recording time: 5 msec, sub-scanning line density: 8 lines / mm, and applied energy per dot: 2.0 mJ, 25
Solid printing of 6 lines was performed, and black color recording in high-temperature printing was performed.

<Evaluation of Color Separability> The color products thus obtained were visually evaluated for color separation, and the results are shown in Table 1. O indicates that a clear red color was obtained at low-temperature coloring and a black color was obtained at high-temperature coloring. × indicates that red was a low-temperature color tone mixed with black and the color was reddish to black, indicating that color separation could not be performed. The results are shown in Table 1.

<Test of Image Storage Stability> As a test of image storage stability of the obtained heat-sensitive recording material after color development, 2
It was immersed at 0 ° C. for 24 hours, and the degree of decoloration was examined. ○ indicates that almost no erasing was observed, and X indicates that the erasing was performed, the printing density was significantly reduced, and the original printing became unrecognizable. Δ indicates that the original printed image was recognizable although the density was reduced. The results are shown in Table 1.

<Surface Fog Test> Further, the heat-sensitive recording material was stored for 100 hours in an environment of a temperature of 55 ° C. and a humidity of 90% RH, and the whiteness of the non-image area (Hunter whiteness, JIS)
P8123) was measured, and the results are shown in Table 1. When the value of whiteness is 75% or more, there is practically no problem in whiteness, but when the value is 70% or less, a slightly dirty impression is given. The results are shown in Table 1.

[0108]

[Table 1]

<Evaluation of Single-Colored Thermosensitive Recording Material>
Thermal printing tester TH-PMD (manufactured by Okura Electric Co., Ltd.) for the four types of single-color heat-sensitive recording materials of Comparative Examples 4 and 5
, One line recording time: 5 msec, sub-scanning line density: 8 lines / mm, applied energy per dot:
Perform solid printing of 256 lines under the condition of 2.0 mJ,
A black color recording was performed. The density of the printed portion of the obtained monochromatic heat-sensitive recording material was measured using a Macbeth densitometer RD914, and the results are shown in Table 2. If the color density is 1.20 or more, there is no practical problem. Further, an image storability test and a background fog test, which were performed in the evaluation of the two-color heat-sensitive recording material, were performed.

[0110]

[Table 2]

[0111]

According to the present invention, it has become possible to produce a thermosensitive recording material which is excellent in image storage stability and has little background fog. Further, according to the present invention, due to the difference in heating application conditions from the thermal head, a multicolor having different color tones is formed, the color tone of low-temperature printing, the color mixture at the time of high-temperature color development, and the background fog are small. It has become possible to produce a heat-sensitive recording material.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasutaka Sachigata 1-10-6 Shinonome, Koto-ku, Tokyo Inside Oji Paper Co., Ltd. Shinonome Research Center (72) Inventor Satoshi Fukui 1-10, Shinonome, Koto-ku, Tokyo No. 6 Oji Paper Co., Ltd. Shinonome Research Center

Claims (9)

[Claims] 1. A heat-sensitive color-forming layer formed on a support, comprising at least one dye precursor, and a color-developing compound which reacts with the dye precursor under heating to develop a color. 55 in a thermosensitive recording material having
A thermosensitive recording material, wherein the whiteness of a non-image part according to JIS P8123 is 70% or more after storage in an environment of 90 ° C. and 90% RH for 100 hours. 2. The thermosensitive coloring layer is obtained by emulsifying and dispersing a solution containing a polyvalent isocyanate compound as a solvent and a dye precursor as a solute in water, and then promoting the polymerization reaction of the polyvalent isocyanate compound. 2. The heat-sensitive recording material according to claim 1, which contains composite fine particles. 3. The thermosensitive coloring layer according to claim 1, wherein the thermosensitive coloring layer contains microcapsules containing a polymer compound as a wall material, a high boiling point solvent as a solvent, and a solution containing a dye precursor as a solute as a core substance. Thermal recording material. 4. The method according to claim 1, wherein the dye precursor is 3-diethylamino-7-chlorofluoran, 3,3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, and 3- (N -Ethyl-N-isoamylamino) -7-
4. The heat-sensitive recording material according to claim 1, which is at least one selected from phenoxyfluorane. 5. A support, two or more kinds of dye precursors formed thereon and emitting colors different from each other, and a color developing property which reacts with the dye precursors under heating to develop the color. A multicolor thermosensitive recording material containing a compound and a multicolor thermosensitive coloring layer.
After storing for 100 hours under RH environment, JIS of non-image part
A thermosensitive recording material having a whiteness based on P8123 of 70% or more. 6. The multicolor thermosensitive coloring layer comprises: (1) a polyvalent isocyanate compound as a solvent and a solution containing a first dye precursor as a solute emulsified and dispersed in water, followed by a polymerization reaction of the polyvalent isocyanate compound. 6. The heat-sensitive recording material according to claim 5, comprising: composite fine particles obtained by accelerating the first dye precursor; and (2) solid fine particles comprising a second dye precursor that develops a color tone different from that of the first dye precursor. 7. A microcapsule, wherein the multicolor thermosensitive coloring layer includes (1) a polymer compound as a wall material, a high-boiling solvent as a solvent, and a solution containing a first dye precursor as a solute as a core substance. 6. The heat-sensitive recording material according to claim 5, further comprising: (2) solid fine particles of a second dye precursor that develops a color tone different from that of the first dye precursor. 8. The method according to claim 1, wherein the second dye precursor is 3-diethylamino-7-chlorofluorane, 3,3′-bis (1-n
-Butyl-2-methylindol-3-yl) phthalide, and 3- (N-ethyl-N-isoamylamino)
At least one selected from -7-phenoxyfluoran
8. The heat-sensitive recording material according to claim 6, which is a seed. 9. The heat-sensitive recording material according to claim 1, wherein the color-developing compound is 2,4-di (benzenesulfonyl) phenol.