JP2000247031A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain versatility and at the same time, increase the amount of information per unit area, and enhance identification and antiforgery properties when a thermal recording material is applied to a normal use. SOLUTION: This thermal recording material has one or more thermal recording layers which develop a color in two or more hues by heating, formed on both faces of an opaque substrate. In this case, one or more of developed hues on the surface and the rear are difference from each other. At the same time, all the developed hues on bath the faces are made different from each other. Consequently, the improvement effect is enhanced. In addition, it is possible to form one or more thermal recording layers capable of forming a color developed image having absorption in a near infrared part by heating and a color developed image having no absorption in the near infrared part, on both faces of the opaque substrate. In this case, it is also possible to make one kind or two kinds of the developed hues visible only on one face.

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 improved information discrimination and forgery prevention.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support having thereon a thermosensitive recording layer mainly comprising a colorless or pale-colored electron-donating dye precursor and an electron-accepting developer. When heated with a hot pen, a laser beam, or the like, the electron-donating dye precursor and the electron-accepting color developer react instantaneously, and an image is obtained. No., for example.

In general, such a heat-sensitive recording material has advantages that an image can be obtained with a relatively simple apparatus, maintenance is easy, and no noise is generated.
Facsimile, printer, computer terminal,
It is widely used in a wide range of fields such as vending machines such as label printing machines and ticketing. In particular, when the heat-sensitive recording material is applied to applications such as tickets, voting tickets, securities, receipt documents, etc., it is desired to improve the discrimination of issued tickets and the prevention of forgery.

Several proposals have been made so far for providing a thermosensitive recording material with a technology for preventing forgery. For example, Japanese Patent Application Laid-Open No. 62-278084 discloses a method in which a colored concealing layer is provided on a thermosensitive coloring layer so that the colored portion and the uncolored portion of the thermosensitive coloring layer cannot be distinguished. JP-A-63-
Japanese Patent No. 126783 discloses a method in which a toner is fixed on a heat-sensitive coloring layer, and the heat-sensitive coloring layer immediately below is fixed. JP Hei 3
JP-A-193349 discloses a method of providing a heat-sensitive recording layer on a magnetic recording layer, which is opaque at room temperature but becomes transparent by heating. JP-A-4-129794 and JP-A-4-182188
Nos. 7,186,554 and 7,266,763, and the like, use a difference in absorptivity in a near infrared wavelength region between a recording portion and a non-recording portion. JP-A-5-278372, ibid.
-249873, 8-216515, Hirakai 4-
No. 126877, 6-29860 and the like, a reversible thermosensitive coloring layer and a printing layer using the same ink as the coloring hue of the coloring layer are provided, or a reversible thermosensitive coloring layer and a hologram layer are combined, A method using a reversible thermosensitive coloring layer, such as a combination of a reversible thermosensitive coloring layer and a general thermosensitive coloring layer. JP-A-6-166264 proposes various methods such as a method in which a fluorescent dye is contained in a heat-sensitive recording layer and pattern printing is performed on the surface thereof with an ultraviolet absorbent. However, all of these require special materials, and after recording, a special light source is required for authenticity judgment.
There were inconveniences in actual use.

Further, Japanese Utility Model Application Laid-Open No. 54-194066 discloses a method in which a thermosensitive coloring layer is provided on both surfaces of a support. Although effective, such as being economical and usable without being conscious of the front and back, the discrimination and anti-counterfeiting properties were still insufficient.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to maintain the versatility when used as a normal thermosensitive recording material, maintain the discriminability of information and a higher level of anti-counterfeiting, and provide a unit. An object of the present invention is to provide a thermosensitive recording material having an increased amount of information per area.

[0007]

Means for Solving the Problems The inventors of the present invention have provided a thermosensitive recording material having at least one thermosensitive recording layer which develops two or more colors by heating on both surfaces of an opaque support. And at least one layer capable of forming a color image having absorption in the near infrared region and a color image having substantially no absorption in the near infrared region on both sides of the opaque support by heating. By adopting a configuration in which the above-described heat-sensitive recording layers are provided, at least one heat-sensitive recording layer that develops two or more colors by heating is provided on one surface of the opaque support, and the other one is provided. By providing at least one or more thermosensitive recording layers capable of forming a color image having absorption in the near infrared region by heating and a color image having substantially no absorption in the near infrared region by heating. Purpose I was able to obtain a heat-sensitive recording material.

Further, at least one heat-sensitive recording layer which develops two or more colors by heating on one surface of the opaque support, or a color image having absorption in the near infrared region by heating and a heat sensitive recording layer having a near infrared region. A structure in which at least one or more heat-sensitive recording layers capable of forming a color image having substantially no absorption are provided, and a heat-sensitive recording layer which develops only one hue by heating is provided on the other surface. As a result, the desired heat-sensitive recording material could be obtained. Further, at least one of at least two or more kinds of coloring components contained in the heat-sensitive recording layer is in the form of particles provided with a coloring control layer obtained by polymerizing a compound having an unsaturated carbon bond on the surface thereof. It has been found that the object can be more effectively achieved by being included in the heat-sensitive recording layer.

In this case, at least one or more of the color hues of at least one heat-sensitive recording layer which develops at least two hues provided on one surface of the opaque support is converted to the support. By using the same hue as at least one of the coloring hues of at least one thermosensitive recording layer that develops at least two kinds of hues provided on the other surface, the versatility and information can be obtained. Thus, a heat-sensitive recording material having excellent discriminative properties and anti-counterfeiting properties was obtained.

[0010] Further, the two opaque supports provided on one surface of
Any one of at least one heat-sensitive recording layer that develops at least one kind of hue has at least one heat-sensitive recording layer that develops at least two kinds of hue provided on the other surface of the support. By using a hue different from any of the coloring hues, it was possible to obtain a heat-sensitive recording material excellent in information discrimination and forgery prevention.

Further, one of the color hues of at least one or more heat-sensitive recording layers that develops at least two hues provided on one surface of the opaque support is blackened. We found that versatility became higher.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The heat-sensitive recording material of the present invention can be formed by arranging an arbitrary portion on a heat-sensitive recording layer provided with necessary information on both sides by a thermal printing method such as thermal head printing or laser irradiation. In this case, different color images can be recorded visually or optically. In other words, by changing the applied energy, two or more types of information patterns having different hues on both surfaces, and an information pattern having absorption in the visible part and an information pattern having absorption in the near infrared part can be randomly selected. Can be formed in parts. By combining these information patterns,
A higher degree of discrimination and forgery prevention can be obtained.

In order to form visually different information recording patterns, it is sufficient to provide at least one or more heat-sensitive recording layers which develop two or more kinds of hues due to differences in thermal energy. In order to form an information recording pattern, at least one or more layers capable of forming a color image having absorption in the near infrared region and a color image having substantially no absorption in the near infrared region due to a difference in thermal energy What is necessary is just to provide a thermosensitive recording layer. These can also be combined, and more advanced information discrimination and forgery prevention can be obtained.

The method of obtaining an information pattern based on visually different color images is not particularly limited as long as the color images have different hues. For example, when a low applied energy is applied, a red color image can be obtained. When formed and given higher applied energy, a black color image may be formed. By applying such a design to both sides, it is possible to obtain an information pattern based on a color image having more hues, one surface being red and black, and the other being red and black. , And one side is yellow, red and blue, the other is also yellow, red and blue, etc.
One side has red and black tones, the other has red and blue tones, and one has yellow, red and blue tones, and the other has red and black tones. One or more of the hues on each side are the same, or one side has red and green tones, and the other side has blue and black tones. Different hues are possible. As described above, the type of the color hue can be arbitrarily designed according to the use and the purpose of use.

The method of obtaining an information pattern based on optically different color images is not particularly limited. For example, when a low applied energy is applied, a color image having substantially no absorption in the near infrared region can be obtained. When formed and given higher applied energy, a colored image having absorption in the infrared region is formed. As a result, a color image of information having absorption in the near-infrared region is formed along with recognition as visible information. The near-infrared region indicates a wavelength region of 650 nm to 1300 nm. That is, a dye having an absorption in the near-infrared region formed with a higher applied energy has an absorption in this wavelength region, and thus can be mechanically read in this wavelength region, but is formed with a lower applied energy. A dye having substantially no absorption in the near infrared region has almost no absorption in this wavelength region and does not hinder any mechanical reading in this wavelength region. The hue of the color image is not particularly limited, but in order to enhance the effect of preventing forgery and tampering, the hue of the image of visible information and the image having absorption in the near infrared region are the same, or the hue of the image having absorption in the near infrared region is the same. It is more preferable that the hue of an image having absorption be a shallower hue, because it makes identification difficult.

That is, the color hue of the heat-sensitive recording layer that forms a color with a low applied energy that gives a visible information image is the same as the color hue of the heat-sensitive recording layer that forms a color with a higher applied energy that gives an image having absorption in the near infrared region. Alternatively, it is preferable that the color hue of the heat-sensitive recording layer that develops color with a low applied energy be colored black. Even if the coloring hue of the heat-sensitive recording layer that develops with higher applied energy is not particularly black, it cannot be visually distinguished from the black of the visible information image by mixing with the black of the heat-sensitive recording layer that develops color with lower applied energy. Good.

The heat-sensitive recording layer according to the present invention contains two or more kinds of color-forming components that develop color upon heating. The color-forming component generally comprises a colorless or pale-colored reactant, and a co-reactant that reacts with the reactant when heated to form a colored substance. This colored substance is recognized as a color image.

The reactant and co-reactant used in the heat-sensitive recording material of the present invention may be any compounds which form a colored body by mutual reaction. Conventionally, inorganic and organometallic compounds and polyvalent hydroxyaromatic compounds have been used. A combination of an electron-donating dye precursor and an electron-accepting developer, a combination of a diazo compound and a coupler such as a hydroxy aromatic compound,
Combinations of imino compounds and isocyanate compounds, and combinations of electron-donating dye precursors and isocyanate compounds are known, and these combinations can be used alone or in combination depending on the application. In order to obtain various hues, it is preferable to use an electron-donating dye precursor.

The inorganic material used in the heat-sensitive recording material of the present invention,
Examples of the organic metal compound include copper nitrate, ferric chloride, iron stearate, copper stearate, silver behenate, iron oleate, and iron benzoate. These can be used alone or in combination of two or more.

The inorganic material used in the heat-sensitive recording material of the present invention,
The amount of the organometallic compound used is 0. 01 to 3.0 g / m ² ,
More preferably, it is used in the range of about 0.03 to 2.0 g / m ² .

The polyvalent hydroxy aromatic compound used in the heat-sensitive recording material of the present invention includes tannic acid, catechol, stearyl gallate, propyl gallate, pyrogallol and the like. These can be used alone or in combination of two or more.

The amount of the polyvalent hydroxy aromatic compound used in the heat-sensitive recording material of the present invention is from 0.01 to 3.0 g / g.
m ² , more preferably in the range of about 0.03 to 2.0 g / m ² .

The colorless or pale-color electron-donating dye precursor which forms a colored substance having substantially no absorption in the near infrared region used in the heat-sensitive recording material of the present invention is generally a pressure-sensitive recording paper or a heat-sensitive recording paper. It is typically used for paper and the like, but is not particularly limited. Specific examples include the following, for example.

Examples of the electron-donating dye precursor which gives a black color by reacting with an electron-accepting developer when heated are 3-dibutylamino-6-methyl-7-anilinofluoran and 3-dibutylamino-7. -(2-chloroanilino) fluoran,
3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 3-diethylamino-7- (o-chlorophenyl) aminofluoran, 3-diethylamino-7
-(2-carbomethoxy-phenylamino) fluoran, 3- (N-cyclohexyl-N-methyl) amino-
6-methyl-7-anilinofluoran, 3- (N-cyclopentyl-N-ethyl) amino-6-methyl-7-anilinofluoran, 3- (N-isoamyl-N-ethyl) amino-6 Methyl-7-anilinofluoran, 3
-(N-ethyl-p-toluidino) -6-methyl-7-
Anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3
-(N-methyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluoran 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-pyrrolidino-6
Methyl-7-p-butylphenylaminofluoran, 3
-Piperidino-6-methyl-7-anilinofluoran and the like. These can be used alone or in combination of two or more.

As the electron-donating dye precursor which exhibits a blue tone by reacting with an electron-accepting developer when heated, 3-bis (p-
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-aminophenyl) -4-azaphthalide, 3- (1-ethyl-2
-Methylindol-3-yl) -3- (2-ethoxy-4-methylaminophenyl) -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-ethoxy-4-dihydroxyaminophenyl) -4-azaphthalide, 3- (1
-Ethyl-2-methylindol-3-yl) -3-
(2-ethoxy-4-dichloroaminophenyl) -4-
Azaphthalide, 3- (1-ethyl-2-methylindo-
Ru-3-yl) -3- (2-ethoxy-4-diallylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy) -4-dimethoxyaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-
Yl) -3- (2-ethoxy-4-dicyclohexylaminophenyl) -4-azaphthalide, 3,3-bis (p
-Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (1-ethyl-2-ethylindole-3)
-Yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-
Propylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide;
3- (1-ethyl-2-methoxyindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-ethoxyindole- 3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-phenylindol-3-yl)-
3- (2-ethoxy-4-diethylaminophenyl)-
4-azaphthalide and the like. These can be used alone or in combination of two or more.

Examples of the electron-donating dye precursor which reacts with an electron-accepting developer when heated to give a reddish color include 3-diethylamino-6-methyl-7-chlorofluoran and 3-cyclohexylamino-6-chlorofluorolane. Fluoran, 3-diethylamino-benzo [a] fluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-N-ethyl-N-isoamylamino-benzo [a] fluoran, 3-N-ethyl-Np
-Methylphenylamino-7-methylfluoran, 3-
Diethylamino-6,8-dimethylfluoran, 3-dibutylamino-6-methyl-7-bromofluoran,
3,6-bis (diethylaminofluoran) -γ-
(4'-nitro) anilinolactam, bis (1-n-butyl-2-methylindol-3-yl) phthalide, bis (1-ethyl-2-methylindol-3-yl) phthalide and the like. These can be used alone or in combination of two or more. In particular, red-colored 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluoran, which is reddish near red, 3
-N-Ethyl-N-p-methylphenylamino-7-methylfluoran is preferred.

Examples of the electron-donating dye precursor which gives a yellow tone upon hot reaction with an electron-accepting developer include 3,6-dimethoxyfluoran, 3-cyclohexylamino-6-chlorofluoran, and 2,6. -Diphenyl-4- (4-dimethylaminophenyl) -pyridine, 2,2-bis (4-
(2- (4-diethylaminophenyl) quinazolyl) oxyphenyl) propane, 4-chloro-N- (4- (N
-(4-methylbenzyl) -N-methylamino) benzylidene) aniline, 1- (2-quinolyl) -2- (3-
Methoxy-4-dodecyloxyphenyl) ethene, 1-
(4-n-dodecyloxy-3-methoxyphenyl)-
2- (2-quinolyl) ethylene and the like. These can be used alone or in combination of two or more.

Examples of the electron-donating dye precursor which reacts with an electron-accepting developer when heated to give a green color include 3-anilino-
7-dibenzylaminofluoran, 3-anilino-6
Methyl-7-dibenzylaminofluoran, 3-pyrrolidino-7-dibenzylaminofluoran, 3-pyrrolidino- (7-cyclohexylanilino) fluoran, 3-
Diethylamino-7-dibenzylaminofluoran, 3
-Diethylamino-6-chloro-7-dibenzylaminofluoran and the like. These can be used alone or in combination of two or more. These electron-donating dye precursors adjust the color hue, so that two or more kinds of electron-donating dye precursors that emit different colors can be used in combination.

Examples of the usually colorless or light-colored electron-donating dye precursor which forms a colored substance having absorption in the near infrared region used in the heat-sensitive recording material of the present invention include, for example, the following. It is not limited.

3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,6-bis (diethylamino) fluorene-9
Fluorene-based compounds such as -spiro-3 '-(6'-diethylamino) phthalide; 3,3-bis [2'-(p-
Dimethylaminophenyl) -2 '-(p-methoxyphenyl) vinyl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [2'-(p-dimethylaminophenyl) -2'- (P-methoxyphenyl) vinyl] -4,
5,6,7-tetrabromophthalide, 3,3-bis [2
'-(P-methoxyphenyl) -2'-(p-pyrrolidinophenyl) vinyl] -4,5,6,7-tetrachlorophthalide, bis (p-dimethylaminostyryl) -p-
Toluenesulfonylmethane, bis (p-diethylaminostyryl) -p-toluenesulfonylmethane, bis (p-dimethylaminostyryl) -benzenesulfonylmethane, 1,1-bis [2 ', 2'-(p-dimethylaminophenyl) Divinyl compounds such as vinyl] -2,2-dinitrileethane;

2-methyl-6-p- (p-dimethylaminophenyl) aminoanilinofluoran, 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran, 2-chloro-6 -P- (p-dimethylaminophenyl) aminoanilinofluoran, 2-diethylamino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran, 2-phenyl-6-p-
(P-phenylaminophenyl) aminoanilinofluoran, 2-benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran, 3-diethylamino-6-p- (p-diethylaminophenyl) aminoani Linofluoran, 2-chloro-3-methyl-6-p-
Fluorane compounds such as (p-phenylaminophenyl) aminoanilinofluoran and the like. These electron donating compounds are used alone or in combination of two or more.

The amount of the electron-donating dye precursor used in the heat-sensitive recording material of the present invention is 0.01 to 3.0 g / m ² ,
More preferably, it is used in the range of about 0.03 to 2.0 g / m ² .

The electron-accepting color developer used in the heat-sensitive recording material of the present invention is typically represented by an acidic substance used in pressure-sensitive recording paper and heat-sensitive recording paper, but is not particularly limited. For example, polyvalent metal salts such as clay substances, phenol derivatives, aromatic carboxylic acid derivatives, N, N'-diarylthiourea derivatives, and zinc salts of organic compounds can be used.

More specifically, clay materials such as acid clay, activated clay, zeolite, bentonite and kaolin, p-phenylphenol, p-hydroxyacetophenone,
-Hydroxy-4'-methyldiphenylsulfone, 4-
Hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 1,1-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) cyclododecane, 2,2-bis (4-hydroxyphenyl) Propane, 2,2-bis (4-hydroxyphenyl) hexane, 2,2-bis (4-hydroxyphenyl) octane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphen) Le) -1-phenylethane,
1,3-di- [2- (4-hydroxyphenyl) -2-
Propyl] benzene, 1,3-di- [2- (3,4-dihydroxyphenyl) -2-propyl] benzene,
4-di- [2- (4-hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone,
2,4'-dihydroxydiphenyl sulfone, 3,3 '
-Dichloro-4,4'-dihydroxydiphenylsulfone, 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone, 3,3'-dichloro-4,4'-dihydroxydiphenylsulfide, 2,2-bis ( Methyl 4-hydroxyphenyl) acetate, butyl 2,2-bis (4-hydroxyphenyl) acetate, 4,4'-thiobis (2-t-butyl-5-methylphenol), benzyl p-hydroxybenzoate, p- Chlorobenzyl hydroxybenzoate, dimethyl 4-hydroxyphthalate, benzyl gallate, stearyl gallate, salicylanilide,
5-chlorosalicylanilide, novolak phenolic resin, modified terpene phenolic resin, 3,5-di-t-butylsalicylic acid, 3,5-di-t-nonylsalicylic acid,
3,5-didodecylsalicylic acid, 3-methyl-5-t-
Dodecyl salicylic acid, 5-cyclohexyl salicylic acid,
Examples include 3,5-bis (α, α-dimethylbenzyl) salicylic acid, 3-methyl-5- (α-methylbenzyl) salicylic acid, and metal salts of zinc, nickel, aluminum, calcium, and the like. In particular, compounds containing an alkyl group in the molecule are preferably used. These can be used alone or in combination of two or more.

The amount of the electron-accepting developer used in the heat-sensitive recording material of the present invention is selected according to the type of the electron-accepting developer used. 50 to 2000% by weight, more preferably 80 to 15% by weight
It is preferable to use it in the range of about 00% by weight.

As the diazo compound used in the heat-sensitive recording material of the present invention, a photo-decomposable aromatic diazonium compound is particularly preferable.
And diazosulfonate compounds. 4-diethylaminobenzenediazonium, 2,5-dibutoxy-4-
Morpholinobenzenediazonium, 2,5-diethoxy-4-tolylthiobenzenediazonium, 4-N-ethyl-N-hydroxyethylbenzenediazonium, 3-
Methyl-4-pyrrolidinobenzenediazonium and the like can be mentioned. These tetrafluoroborate salts, hexafluorophosphate salts and the like have high hydrophobicity and are preferred salts. These can be used alone or in combination of two or more.

The amount of the diazo compound used in the heat-sensitive recording material of the present invention is preferably in the range of about 0.01 to 2.0 g / m ² , more preferably about 0.03 to 1.0 g / m ^2. preferable.

As the coupler which reacts with the diazo compound used in the heat-sensitive recording material of the present invention to form a colored product, a hydroxy aromatic compound or an active methylene compound is preferable. , 2,3-dihydroxynaphthalene,
2,3-dihydroxy-6-sulfanylnaphthalene,
1,5-dihydroxynaphthalene, dihydroxybiphenyl, 2-hydroxy-3-naphthoic acid anilide, 2-
Hydroxy-3-naphthoic acid tetradecylamide, benzoylacetanilide, 1-phenyl-3-phenylacetamido-5-pyrazolone and the like can be mentioned. These can be used alone or in combination of two or more.

The amount of the coupler which reacts with the diazo compound used in the heat-sensitive recording material of the present invention to form a colored body is 0.01 to 3.0 g / m ² , more preferably 0.04 to 3.0 g / m ² .
It is preferable to use in a range of about 1.5 g / m ² .

When a diazo compound is used, it is preferable to add a basic compound in order to improve the reactivity. Specifically, organic amines such as tricyclohexylamine, guanidines such as 1,2-dicyclohexyl-3-phenylguanidine, ureas such as allyl urea and ethylene thiourea, imidazoles such as 4-phenylimidazole, and dibenzylpiperazine And the like, and piperidines, amidines, pyrroles, morpholines and the like. These can be used alone or 2
A mixture of more than one species can be used.

The isocyanate compound used in the heat-sensitive recording material of the present invention has at least one isocyanate group in the molecule and is a compound that can be added to the quenching agent and the color-forming component described below at least under heating conditions. A colorless or pale-colored aromatic isocyanate compound or heterocyclic isocyanate compound which is solid at ordinary temperature is preferable.

Specifically, examples of the isocyanate compound include 2,6-dichlorophenyl isocyanate, p
-Chlorophenyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-dimethylbenzene-4,6-diisocyanate, 1,4-dimethylbenzene-2,5-di Isocyanate, 1-methoxybenzene-2,4-diisocyanate, 1-methoxybenzene-2,5-diisocyanate, 1-ethoxybenzene-2,4-diisocyanate, 2,5-dimethoxybenzene-1 , 4-diisocyanate, 2,5-diethoxybenzene-1,4-diisocyanate, 2,5-dibutoxybenzene-1,4-diisocyanate, azobenzene-4,4'-diisocyanate, Diphenyl ether-4,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-dii Cyanate, naphthalene-2,6
-Diisocyanates, naphthalene-2,7-diisocyanates,

3,3'-dimethylbiphenyl-4,4 '
-Diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 3,3'-dichlorobiphenyl-4,4'-diisocyanate, 3,3 ',
6,6'-tetrachlorobiphenyl-4,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenyldimethylmethane-4,4'-diisocyanate, benzophenone-3,3'-di Isocyanate, fluorene-2,7-diisocyanate, anthraquinone-2,6-diisocyanate, 9-ethylcarbazole-3,6-diisocyanate, pyrene-3,8
Diisocyanate, naphthalene-1,3,7-triisocyanate, biphenyl-2,4,4'-triisocyanate, 4,4 ', 4 "-triisocyanatotriphenylamine, 4,4', 4 "-triisocyanate-
2,5-dimethoxytriphenylamine, p-N, N-
Dimethylaminophenyl isocyanate, 5,7-diisocyanate-1,1-dimethyl-6-n-propylindane, 5,7-diisocyanate-1,1,4,6-
Tetramethylindane, and tris (4-phenylisocyanate) thiophosphate, and the like.

If necessary, these isocyanate compounds may be used as so-called block isocyanates, which are addition compounds with phenols, lactams, oximes and the like, and may be used as dimer diisocyanates. For example, a dimer and a trimer of 1-methylbenzene-2,4-diisocyanate may be used as isocyanurate. Further, it can be used as a polyisocyanate reacted with various polyols and the like, for example, a reaction of tolylene diisocyanate and trimethylolpropane. Further, the isocyanate compound is a block isocyanate or diisocyanate.
The monomer, the trimer, and the polyisocyanate may be used alone or in combination of two or more.

The imino compound used in the heat-sensitive recording material of the present invention, which reacts with an isocyanate compound upon heating to form a colored body, contains one or more imino groups in the molecule. And the like.

3-iminoisoindoline-1-one, 3
-Imino-4,5,6,7-tetrachloroisoindoline-1-one, 3-imino-5,6-dichloroisoindoline-1-one, 3-imino-4,5,7-trichloro-6- Methoxyisoindoline-1-one, 1-ethoxy-3-iminoisoindoline, 1,3-diiminoisoindoline, 1,3-diimino-4,5,6,7-tetrachloroisoindoline, 1,3- Diimino-6-methoxyisoindoline, 1,3-diimino-6-cyanoisoindoline, 7-amino-2,3-dimethyl-5-
Oxopyrrolo [3,4b] pyrazine, 1- (2'-cyano-4'-nitrophenylimino) -3-iminoisoindoline, 1- (2'-chloro-5'-cyanophenylimino) -3-iminoiso Indoline, 1- (2 ',
5'-diethoxyphenylimino) -3-iminoisoindoline, 1- (4'-N, N-dimethylaminophenylimino) -3-iminoisoindoline, 1- (2'-
Methoxy-5'-N-phenylcarbamoylphenylimino) -3-iminoisoindoline, 1- (3'-dimethylamino-4'-methoxyphenylimino) -3-iminoisoindoline, 1- (4'-phenylamino Phenylimino) -3-iminoisoindoline, 1- (p-
Phenylazophenylimino) -3-iminoisoindoline, 1- (N-ethylcarbazolyl-3'-imino)
-3-iminoisoindoline, 1- (naphthoquinone-
1'-imino) -3-iminoisoindoline, 1- (pyridyl-4'-imino) -3-iminoisoindoline,
1- (benzimidazolyl-2'-imino) -3-imino-4,7-dithiotetrahydroisoindoline, 1-
[(Cyanobenzimidazolyl-2 ')-methylene]-
3-imino-6-chloroisoindoline, 3-imino-
1-sulfobenzoic acid imide, 3-imino-1-sulfo-
6-chlorobenzoic imide, 3-imino-1-sulfo-
6-nitrobenzoimide, 3-imino-1-sulfonaphthoic imide, 3-imino-1-sulfo-5-bromonaphthoic imide, and 3-imino-2-methyl-
4,5,6,7-tetrachloroisoindoline-1-one and the like.

The amount of the isocyanate compound used in the heat-sensitive recording material of the present invention is usually 0.1 to 2.0 g / m ² as the isocyanate compound, but is particularly preferably 0.2 to 1.5 g. / M ² is preferred for obtaining a high color density. The amount of the electron-donating dye precursor or imino compound is suitably from 10 to 300% by weight, preferably from 20 to 250% by weight, based on the isocyanate compound.

The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention, as disclosed in JP-A-8-282115,
A color-forming component, such as at least one of the electron-donating dye precursors;
The seed may be encapsulated in a microcapsule, or may be contained in the heat-sensitive recording layer in the form of particles in which a color-controlling layer is provided on the surface of one or more compounds of the color-forming component. Further, it is preferable to adjust the temperature for color development by incorporating at least one of the color-forming components into the resin to form a heat-sensitive recording layer that develops two or more hues in a one-layer structure. By laminating more than one heat-sensitive recording layer, and using a color-forming component such as an electron-donating dye precursor having a different color hue, a diazo compound or the like in each layer, as a heat-sensitive recording layer that develops two or more hues. Is also good. In this case, a decoloring layer adjacent to each thermosensitive coloring layer may be provided.

The decoloring layer is a layer having a function of decoloring a colored substance formed by heating in the heat-sensitive recording layer laminated on the decoloring layer, or obtaining sharpness and vividness of a color image. The decoloring agent contained in the decoloring layer differs depending on the type of the coloring component. For example, when the color-forming component is composed of an electron-donating dye precursor, petroleum resins, aromatic resins, oligomers such as ester resins, polymers, guanidine-based, piperidine-based primary and secondary and tertiary amines, Amides, esters and the like are used.

When the color-forming component used in the heat-sensitive recording material of the present invention is contained in the heat-sensitive recording layer in the form of a particle having a color-controlling layer provided on at least one surface of the color-forming component, the color-controlling layer may be formed of a particle. By providing on the surface, it is possible to raise or lower the coloring temperature and adjust the coloring energy.

The color control layer provided on the particle surface of at least one or more color components used in the heat-sensitive recording material of the present invention is preferably obtained by polymerizing a compound having an unsaturated carbon bond. Although the color control layer can be provided by using the conventional method for producing microcapsules, the characteristics of the color control layer can be freely controlled by providing a color control layer obtained by polymerizing a compound having an unsaturated carbon bond. It is more preferable because it can be performed.

As a method of forming the color control layer on the surface of the particles, for example, a compound having an unsaturated carbon bond is added to a dispersion of the compound particles constituting the color forming component, and a polymerization initiator is added. By heating in accordance with the formula (1), the unsaturated carbon bond in the compound having an unsaturated carbon bond becomes an active site, undergoes addition polymerization, and can be formed by coating the surface of the particles of the compound constituting the color-forming component.

The dispersion of the compound constituting the color-forming component used in the present invention may be prepared by a method in which the compound constituting the color-forming component is dry-pulverized and dispersed in a dispersion medium, or by mixing the compound constituting the color-forming component into a dispersion medium. It can be obtained by a wet pulverizing method or the like. Any method can be used as a method for pulverizing. The particle size of the compound particles constituting the color-forming component in the dispersion of the compound constituting the color-forming component is from 0.1 μm to 2 μm.
It is preferably 0 μm or less. When the particle size is in this range in the present invention, it is possible to efficiently provide a color control layer,
It is also advantageous from the viewpoint of easy production of the dispersion and the printability of the heat-sensitive recording material.

In the present invention, water or a mixed solution of water and an organic solvent compatible with water is preferably used as the dispersion medium in which the particles of the compound constituting the color-forming component are dispersed. Specific examples of water-soluble organic solvents include:
Examples thereof include methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, and ethylene glycol, but are not particularly limited as long as they are organic solvents compatible with water. Furthermore, in the present invention, it is preferable that water accounts for 50% by weight or more of the total weight of the dispersion medium in which the compound particles constituting the color-forming component are dispersed. When 50% by weight or more of the total weight of the dispersion medium is composed of water, when a compound having an unsaturated carbon bond is subjected to addition polymerization to form a color control layer on the surface of compound particles constituting a color forming component, The dispersion stability of the compound particles constituting the color-forming component is good, the aggregation of the compound particles constituting the color-forming component hardly occurs, and the formation of the color-controlling layer due to the aggregation is hardly hindered.

In the present invention, when a compound having an unsaturated carbon bond is added to a dispersion of compound particles constituting a color-forming component having a surface on which a color-controlling layer is provided, the compound is added in the form of a suspension. Is preferred. When the compound having an unsaturated carbon bond is added to the dispersion of the compound particles constituting the heat-sensitive recording component, a small amount of the unsaturated carbon bond is added by suspending and adding the compound having the unsaturated carbon bond in a dispersion medium. A coloring control layer can be provided on the surface of the compound particles constituting the coloring component with the compound having the coloring agent efficiently, and the coloring properties such as the coloring temperature of the coloring component can be adjusted.

In the present invention, by changing the characteristics of the color-controlling layer, the characteristics such as the color-forming temperature, solvent resistance and storage stability of the heat-sensitive recording material containing the color-forming component provided with the color-controlling layer can be significantly changed. Can be. As a method of changing the characteristics of the color control layer, it can be easily realized by changing the type and amount of the compound having an unsaturated carbon bond.

The compound having an unsaturated carbon bond according to the present invention is a compound having one or more unsaturated carbon bonds. This makes it possible to freely change the characteristics of the color control layer. The color control layer formed by mixing and polymerizing a compound having one unsaturated carbon bond and a compound having two or more unsaturated carbon bonds has an unsaturated structure due to a cross-linked structure of the polymer forming the color control layer. Compared with a color control layer formed by polymerization without containing a compound having two or more carbon bonds, resistance to external stimuli such as heat and an organic solvent is improved.

Further, as the content of the compound having two or more unsaturated carbon bonds increases, the color control layer has a higher-density crosslinked structure, and heat resistance and solvent resistance are improved. The content of the compound having two or more unsaturated carbon bonds is 1 to the total weight of the compound having the unsaturated carbon bond.
It is preferably in the range of not less than 70% by weight and not more than 70% by weight. Within this range, the coloring properties such as the coloring temperature of the coloring component in the thermosensitive recording material can be freely adjusted over a wide range.
Furthermore, a substance that causes the thermosensitive recording material to develop color, for example,
Even if an organic solvent or the like adheres to an unprinted portion, it is difficult to form a color, and it is possible to obtain a thermosensitive recording material having a high coloring density in a printed portion and capable of performing uniform printing.

The amount of the compound having an unsaturated carbon bond to be used is preferably 0.5% by weight or more and 1000% by weight or less with respect to the compound particles constituting the color forming component for providing the color controlling layer. 0.5% by weight or more and 1000% by weight with respect to the compound particles constituting the color forming component for providing the color forming control layer
In the case of the following, a coating having a sufficient function as a color-developing layer can be provided, polymerization can easily proceed, aggregation does not easily occur at the time of polymerization, and a color-developing density of the heat-sensitive recording material is sufficient.

Specific examples of the compound having only one unsaturated carbon bond according to the present invention include styrene, α-methylstyrene, α-methoxystyrene, m-bromostyrene, m-chlorostyrene, o-bromostyrene, o-chlorostyrene, p-bromostyrene, p-chlorostyrene, p-methylstyrene, p-methoxystyrene, 2-
Vinyl pyridine, isobutene, 3-methyl-1-butene, butyl vinyl ether, methyl vinyl ketone, nitroethylene, vinylidene cyanide, ethylene, propylene, vinyl chloride, vinyl acetate, acrolein, methyl acrolein, acrylamide, N-methylol acrylamide, N , N-dimethylacrylamide, diacetone acrylamide, N-octadecylacrylamide, α
-Ethyl acetoxyacrylate, ethyl α-chloroacrylate, methyl α-chloroacrylate, methyl α-cyanoacrylate, methyl α-phenylacrylate, benzyl acrylate, butyl acrylate, ethyl acrylate,
2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, tridecyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,

2-methoxyethyl acrylate, 2-butoxyethyl acrylate, ethoxyethyl acrylate, methyltriglycol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, cyanoethyl acrylate, ferrocenylmethyl acrylate ,
Glycidyl acrylate, heptafluorobutyl acrylate, methyl acrylate, octyl acrylate, methyl trifluoroacrylate, 2-chloroethyl acrylate, 2-nitrobutyl acrylate, acrylic acid, α-
Bromoacrylic acid, 2-hydroxyethylacryloyl phosphate, acrylonitrile, allyl glycidyl ether, allyl acetic acid, allyl alcohol, allyl benzene, N-allyl stearyl amide, 1-butene, 2-butene, N-vinyl caprolactam, N-vinyl carbamic acid Ethyl, N-vinylcarbazole, crotonaldehyde, crotonic acid, 1,1-diphenylethylene, tetrafluoroethylene, diethyl fumarate, 1-hexene, 1-vinylimidazole, 1-vinyl-2-methylimidazole, indene, maleic acid Diethyl, maleic anhydride, maleimide, methacrylamide, benzyl methacrylate, ethyl methacrylate, ferrocenylmethyl methacrylate, glycidyl methacrylate, isopropyl methacrylate, meth Acrylic acid propyl, methacrylic acid -
n-butyl,

Isobutyl methacrylate, methacrylic acid
sec-butyl, t-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate, lauryl methacrylate,
Tridecyl methacrylate, stearyl methacrylate, methyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, dimethylamino methacrylate Ethyl, diethylaminoethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, methacrylic acid, methacryloxyethyl phosphate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, N-methylol methacrylamide, methacrylonitrile, methacryloyl acetone , 2-isopropenyl-2-oxazoline, 2-vinylquinoline, vinyl benzoate, vinyl dodecyl ether, vinyl Ethyl sulfoxide, vinyl formate, vinyl isobutyl ether, vinyl laurate, vinyl phenyl ether, acetylene, although such phenylacetylene and the like, and the present invention is not limited thereto.

The compound having two or more unsaturated carbon bonds is defined as having a carbon-carbon double bond and / or a carbon-carbon triple bond which can be added and polymerized by opening an unsaturated carbon bond in one molecule. Those having two or more are preferably used.

As specific examples, polyethylene glycol diacrylates such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, octaethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate , Polyethylene glycol dimethacrylates such as triethylene glycol dimethacrylate and tetraethylene glycol dimethacrylate, 2,2-bis (4-acryloxyethoxyphenyl) propane, 2,2-bis (4-acryloxydiethoxyphenyl) propane And 2,2-bis (4-acryloxytriethoxyphenyl) propane and the like.
2-bis (4-acryloxypolyethoxyphenyl) propanes, 2,2-bis (4-methacryloxyethoxyphenyl) propane, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, 2,2- Screw (4-
2,2-bis (4-methacryloxypolyethoxyphenyl) propanes such as methacryloxytriethoxyphenyl) propane,

Allyl acrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polypropylene glycol Diacrylate, N, N'-methylenebisacrylamide, allyl methacrylate, 1,3-butanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol dimethacrylate, diallyl phthalate, diallyl chloride Lendate, butadiene, ethyl butadiene-1-carboxylate, diethyl butadiene-1,4-dicarboxylate, diallyl melamine, diallyl phthalate, N, N-di Niruanirin, divinyl ether,
Divinylbenzene, divinylnaphthalene, 1,3-butanediol dimethacrylate, isoprene, etc., pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate , Triallyl trimellitate, etc., tetramethylolmethane tetraacrylate, tetramethylolmethanetetramethacrylate, etc., but the present invention is not limited thereto.

The compounds having one or more unsaturated carbon bonds according to the present invention can be used alone or in combination of two or more. When two or more kinds are used in combination, as described above, a combination of a compound having one unsaturated carbon bond and a compound having two or more unsaturated carbon bonds in a specific ratio is preferable. May be used in combination with one compound having one or two compounds having two or more unsaturated carbon bonds.

When 50% by weight or more of the total weight of the dispersion medium in which the compound particles constituting the color forming component are dispersed is composed of water, the compound having an unsaturated carbon bond may be benzyl methacrylate or ethyl methacrylate. , Ferrocenylmethyl methacrylate, glycidyl methacrylate, isopropyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, -sec-butyl methacrylate, -t-butyl methacrylate,
2-ethylhexyl methacrylate, cyclohexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, methyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, methacrylic acid-2
-Hydroxypropyl, 2-ethoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, methacryloxyethyl phosphate, polyethylene glycol mono Methacrylate, polypropylene glycol monomethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, allyl methacrylate, 1,3-butanediol dimethacrylate,
Methacryl such as neopentyl glycol dimethacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, trimethylolethanetrimethacrylate, trimethylolpropanetrimethacrylate, tetramethylolmethanetetramethacrylate, etc. It is particularly preferable to use an acid ester for part or all of the compound having an unsaturated carbon bond.

As the polymerization initiator to be added for the addition polymerization of the compound having an unsaturated carbon bond, known polymerization initiators can be used, and the type of polymerization reaction is not particularly limited, such as radical polymerization, anionic polymerization, and cationic polymerization. Radical polymerization is particularly preferably used. During the polymerization, the system may be heated as required. Specific examples of the polymerization initiator for radical polymerization are shown below. Hydrogen peroxide, cumene hydroperoxide, t-butyl hydroperoxide, dichloro peroxide, di-t-butyl peroxide, benzoyl peroxide, peroxides such as lauroyl peroxide, potassium persulfate, persulfates such as ammonium persulfate, 2,2 '
-Azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionamidine) dihydrochloride, azo compounds such as 4,4'-azobis (4-cyanovaleric acid), a combination of hydrogen peroxide and ferrous salt, a combination of persulfate and sodium acid sulfite, cumene Redox initiators such as a combination of hydroxyperoxide and a ferrous salt, a combination of benzoyl peroxide and diethylaniline, a combination of a peroxide and a metal alkyl, and a combination of oxygen and an organic metal alkyl are exemplified.

These are not limited to use alone, and may be used as a mixture. In addition, if the color-developing layer is provided on the surface of the compound particles constituting the color-forming component in two or more portions, the polymerization initiator to be added for polymerizing the compound having an unsaturated carbon bond two or more times is once Alternatively, it is added in two or more portions. When the polymerization initiator is added in two or more portions, a single or mixed polymerization initiator may be used for each addition, or a different single or mixed polymerization initiator may be used for each addition. May be.

The polymerization initiator for radical polymerization is not particularly limited as long as it generates active radicals by the energy of heat or light other than those described above, but is not particularly limited, and is a dispersion medium for dispersing compound particles constituting a color-forming component. 50 of the total weight of
When the weight percentage is more than water, it is particularly preferable to use a water-soluble polymerization initiator such as potassium persulfate, ammonium persulfate, and 2,2'-azobis (2-methylpropionamidine) dihydrochloride.

The amount of the polymerization initiator to be added is not particularly limited as long as the compound having an unsaturated carbon bond initiates the addition polymerization. The content is preferably 0.001 to 10% by weight based on the compound having a bond. When a compound having an unsaturated carbon bond is subjected to addition polymerization twice or more, the ratio of the amount of the polymerization initiator to the compound having an unsaturated carbon bond may be the same or different.

In the heat-sensitive recording material of the present invention, when a color-adjusting layer is provided for a compound that determines the absorption wavelength of a color-forming component among the compounds constituting the color-forming components, a plurality of color-forming components are contained in the same layer. This is particularly preferred because The absorption wavelength of the color former by the electron donating dye precursor and the electron accepting color developer generally depends on the type of the electron donating dye precursor. Therefore, when two types of electron-donating dye precursors are used, an electron-accepting developer is used in common for both color-forming components, and a color-forming control layer is provided on the surface of one electron-donating dye precursor particle, and The heat-sensitive recording material capable of obtaining a color-developed image having two different absorption wavelengths depending on the heating temperature can be obtained by including the same electron-donating dye precursor and electron-accepting developer in the same layer. Can be

That is, when the heating is carried out at a lower temperature, the near-infrared region composed of the electron-donating dye precursor having no color-developing layer on its surface and the electron-accepting color developer has substantially no absorption. At a higher temperature, a color-developed image is obtained, and when heated at a higher temperature, the electron-donating dye precursor provided with the color-developing layer on the surface and the electron-donating dye precursor provided with the color-developing layer on the surface exhibit electron accepting properties. By reacting with the colorant, a color image having absorption in the near infrared region can be obtained.

The thickness of the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention is preferably in the range of 0.5 μm to 30 μm on one surface, particularly preferably in the range of 1 μm to 20 μm. Within this range, even when the heat-sensitive recording layers are laminated, it is possible to clearly confirm the recording obtained by coloring the heat-sensitive recording layer provided below. The heat-sensitive recording layer itself may be optically opaque, but when laminated, it is more preferable that the heat-sensitive recording layer is transparent or translucent, and the haze value of the heat-sensitive recording layer is preferably 80% or less. It is particularly preferably at most 60%.

The heat-sensitive recording material of the present invention is formed by providing a heat-sensitive recording layer on both sides of an opaque support. The heat-sensitive recording layer is formed by providing a coating solution or ink for the heat-sensitive recording layer containing a coloring component, that is, a compound of a reactant and a coreactant, on a support. As a method of including in the coating liquid or the ink, a method of individually dissolving each compound in a solvent or dispersing in a dispersion medium and then mixing, or a method of mixing and dissolving each compound in a solvent or a dispersion medium And a method in which each compound is heated and dissolved to homogenize, then cooled, and then dissolved in a solvent or dispersed in a dispersion medium, but the method is not particularly limited. If necessary, a dispersing aid may be used for dispersion.
When water is used as the dispersion medium, examples of the dispersion aid include water-soluble polymers such as polyvinyl alcohol and various surfactants. Further, a water-soluble organic solvent such as ethanol may be mixed. When an organic solvent typified by hydrocarbons is used as a dispersion medium, lecithin or phosphates may be used as a dispersion aid. Further, a binder may be used in the heat-sensitive recording layer, if necessary. The binder contained in the heat-sensitive recording layer is not particularly limited, but those having less influence on the color-forming properties of the color-forming component are particularly preferably used.

The average particle size of the color-forming component contained in the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention is usually 7 μm or less, preferably 0.1 to 5 μm, particularly preferably 0.1 to 2 μm.
Is preferable. If the average particle size exceeds 7 μm, light scattering is likely to occur, the transparency of the heat-sensitive recording layer is impaired, and more energy is required to obtain a color image.

As described above, a binder can be added to the heat-sensitive recording layer for the purpose of improving the strength of the heat-sensitive recording layer. Specific examples of the binder include, for example, polyvinyl alcohol completely or partially saponified with a water-soluble binder, modified polyvinyl alcohol such as cation-modified and silanol-modified, carboxy-modified polyvinyl alcohol, starch and oxidized starch, carboxymethyl cellulose, and hydroxymethyl. Cellulose, hydroxyethyl cellulose, modified cellulose such as cellulose sulfate, gelatin, casein, pullulan, gum arabic, karaya gum, natural polymers such as albumin or derivatives thereof, polyacrylamide, polyvinylpyrrolidone, polypropylene glycol, polyethylene glycol, polyacryl Sodium acrylate, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid Synthetic polymers such as terpolymer, sodium salt of styrene-maleic anhydride copolymer, and sodium polystyrene sulfonate are used. As the hydrophobic binder, polyvinyl acetate, polyurethane, polyacrylate, styrene / butadiene copolymer are used. Copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl chloride copolymer, polyvinyl chloride, ethylene / vinylidene chloride copolymer, polyvinylidene chloride, etc. Latex, etc.
The present invention is not particularly limited to these, and they can be used alone or in combination.

Further, a sensitizer may be contained in the heat-sensitive recording layer as an additive for adjusting the color development sensitivity of the heat-sensitive recording layer. These compounds preferably have a melting point of 60C to 200C, particularly preferably compounds having a melting point of 80C to 180C. In addition, sensitizers used in general thermosensitive recording paper can also be used. These compounds include N-hydroxymethyl stearamide, behenamide, stearamide, palmitamide, oleamide, ethylenebissteaamide, ricinoleamide, paraffin wax, microcrystalline wax, polyethylene wax, Waxes such as carnauba wax, 2-
Naphthol derivatives such as benzyloxynaphthalene, p
-Biphenyl derivatives such as -benzylbiphenyl and 4-allyloxybiphenyl, m-terphenyl, 1,2-bis (3-methylphenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4 -Methoxyphenyl) ether and other polyether compounds, diphenyl carbonate, dibenzyl oxalate, carbonic acid or oxalic acid diester derivatives such as bis (p-methylbenzyl) oxalate, and the like. These may be added in combination of two or more. Can also.

When the sensitizer is added to a heat-sensitive recording layer containing, as main components, an electron-donating dye precursor, an aromatic isocyanate compound and a diazo compound as a color-forming component,
It is preferably used in an amount of 10 to 400% by weight, more preferably 30 to 350% by weight, based on the color-forming component.

A protective layer can be provided on at least one of the heat-sensitive recording layers provided on both sides of the heat-sensitive recording material of the present invention. The protective layer is formed mainly of a material such as a water-soluble polymer and latex. In this case, a hardener such as a compound having an epoxy group or a zirconium salt or a crosslinking agent may be added. In addition, a protective layer may be formed by coating and curing a light and electron beam curable resin or a thermosetting resin. Further, a protective film may be formed by laminating a plastic film. Further, a pigment or the like may be added in order to further improve the writing property and the running property. The average particle size of the pigment used in the protective layer is preferably 2.0 μm or less in order to increase the image density. The coating amount of the protective layer is 0.2 to 10 g
/ M ² , preferably 1 to 5 g / m ² , and may have a multilayer structure of two or more layers as necessary.

Specific examples of the resin used to form the protective layer include starches, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol,
Modified polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, sodium polyacrylate, polyethylene terephthalate, polybutylene terephthalate, chlorinated polyether, allyl resin, furan resin, ketone resin, oxybenzoyl Polyester, polyacetal, polyetherketone, polyethersulfone, polyimide, polyamide, polyamideimide, polyaminobismaleimide,
Polymethylpentene, polyphenylene oxide, polyphenylene sulfide, polyphenylene sulfone, polysulfone, polyarylate, polyallylsulfone, polybutadiene, polycarbonate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyurethane, phenolic resin, urea Resin, melamine resin, melamine formalin resin, benzoguanamine resin, bismaleimide triazine resin, alkyd resin, amino resin, epoxy resin, unsaturated polyester resin, styrene / butadiene copolymer,
Acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, acrylamide / acrylic ester copolymer, acrylamide / acrylic ester / methacrylic acid terpolymer And styrene / maleic anhydride copolymer alkali salts, ethylene / maleic anhydride copolymer alkali salts or ammonium salts, and various other polyolefin-based resins.
A mixture of more than one species can be used.

The pigment used for the heat-sensitive recording layer and / or the protective layer includes diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea -Pigments such as formalin resins. Other additives include head wear prevention,
For the purpose of preventing sticking and the like, dispersing metal salts of higher fatty acids such as zinc stearate and calcium stearate, waxes such as paraffin, paraffin oxide, polyethylene, polyethylene oxide, stearamide and custard wax, and sodium dioctyl sulfosuccinate Agents, surfactants, fluorescent dyes and the like can also be used.

Further, in the heat-sensitive recording material of the present invention, between the heat-sensitive recording layer and the protective layer, between the heat-sensitive recording layer and the heat-sensitive recording, if necessary, in order to obtain thermal adjustments such as smoothness, heat transfer and heat insulation and hue adjustment. Between the layers, or between the thermosensitive recording layer and the support,
An intermediate layer containing at least one of a water-soluble polymer, a white or colored dye, a hollow particle, and a decoloring agent can be provided. In this case, the protective layer and / or the intermediate layer may be composed of two or three or more layers. The coating amount when this intermediate layer is provided is 0.1 to 30 g / m ^2.
And more preferably in the range of 0.5 to 15 g / m ² . The heat-sensitive recording layer may be a multilayer of two or more layers by containing each component one by one or changing the mixing ratio for each layer. Further, a material capable of recording information electrically, optically, and magnetically may be included in the heat-sensitive recording layer and / or another layer or the uppermost layer. Further, an anti-blocking agent and an anti-static agent can be added to the coating layer on the surface.

The pigments used in the intermediate layer include calcined kaolin, kaolin, talc, calcium carbonate, zinc oxide, diatomaceous earth, aluminum hydroxide, magnesium hydroxide,
Inorganic pigments such as silica and alumina, and organic pigments such as styrene / acrylic resin, polystyrene resin, acrylic resin, polyethylene resin, polypropylene resin, and urea / formalin resin can be used. Also,
In order to obtain heat insulation properties, inorganic and organic pigments having many pores, hollow particles, expandable hollow particles, and air capsules containing air therein can also be used.

The decoloring agent used for the intermediate layer is used as necessary, particularly when two or more heat-sensitive recording layers are laminated. Specifically, oligomers such as petroleum resins, aromatic resins, and ester resins, polymers, primary, secondary, and tertiary amines, amides, and esters are used.

As the binder used for the intermediate layer, conventionally known latexes and water-soluble polymers can be used. That is, latexes include styrene / butadiene latex, acrylonitrile / butadiene / styrene latex, vinyl acetate resin, vinyl acetate / acrylate copolymer, styrene / acrylate copolymer, acrylate resin, and polyurethane resin Etc. can be used. Examples of the water-soluble polymer include polyvinyl alcohol, starch and derivatives thereof, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinyl pyrrolidone, acrylamide / acrylate copolymer, acrylamide / Acrylic ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and the like can be used.

The opaque support used in the present invention is a support having such a degree of opacity that a color image formed by a heat-sensitive recording layer provided on one side of the support cannot be confirmed from the other side. To tell. As the opaque support, synthetic resin films such as polyester and polyolefin,
Examples include paper, various nonwoven fabrics, woven fabrics, and synthetic papers. In addition, a support obtained by laminating a synthetic resin such as polyethylene or polypropylene on these supports, a support obtained by evaporating a metal or the like, or a composite sheet obtained by combining these various supports by lamination or the like is optionally used according to the purpose. be able to.

The opaque support of the present invention may be provided with an anchor layer for the purpose of improving the adhesion between the heat-sensitive recording layer and the support. A hydrophilic binder such as gelatin and PVA, a solvent-soluble binder such as butyral resin, a latex, a curing agent, a pigment, a surfactant and the like can be appropriately added to the anchor layer.

The thickness of the opaque support used in the present invention does not need to be particularly limited.
It is selected in the range of μm, and is preferably about 20 to 200 μm in view of handling properties, suitability for paper passing of the printer, and the like. Further, in order to impart cushioning properties and concealing properties, a void-containing film containing a large number of voids inside the film can also be used.

The synthetic paper is not particularly limited as long as it is formed by converting a high molecular compound represented by polyolefins, polystyrenes, polyesters, polyamides and the like into a paper by internal paper or surface paper. The paper support is not particularly limited, and generally used paper can be used.
Preferably, smooth base paper is preferred. As the pulp constituting the base paper, natural pulp, recycled pulp, synthetic pulp and the like can be used alone or in combination of two or more. Those having good surface smoothness are preferable, and JIS-P-8
Those having a Beck's smoothness of at least 50 seconds measured in 119 are particularly preferred.

In the present invention, the method for providing a heat-sensitive recording layer, a protective layer, and an intermediate layer on an opaque support is not particularly limited, and can be formed by a conventional method.
For example, coating equipment such as air knife coater, blade coater, bar coater, curtain coater, lithographic printing plate,
Various printing machines using a relief printing, intaglio printing, flexo, gravure, screen, hot melt and other methods can also be used. Drying of the respective layers can be performed by UV irradiation or EB irradiation depending on the type of the binder used, in addition to the usual drying steps such as an air dryer and an infrared method.

[0092]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. The percentages and parts shown below are% by weight and parts by weight, respectively. The coating amount is an absolutely dry coating amount.

Example 1 (1) Preparation of Opaque Support A 1: 1 mixture of hardwood bleached kraft pulp (LBKP) and softwood bleached kraft pulp (NBKP) was dispersed in water at a concentration of 4% in a double disc refiner. Using a Canadian Standard Freeness Tester, the mixture was beaten to 300 ml. To this pulp slurry, an alkyl ketene dimer was added as a sizing agent to 0.3% by weight of pulp, a polyacrylamide as a strength enhancer was added to 1.0% by weight of pulp, and a cationic starch was added to 2.0% by weight of pulp. To give a 1% slurry. The slurry was weighed at 70 g / m by a fourdrinier paper machine.
^Then , a size press was applied using a size press to apply a polyvinyl alcohol 4% and a 0.5% concentration of a dimethylamine / epichlorohydrin polycondensate Polyfix P601 (manufactured by Showa Polymer) 0.5%. A paper support for use in the heat-sensitive recording material of the present invention was produced.

(2) Preparation of a thermosensitive recording material in which both sides of the support are colored black and red by heating. Preparation of Microcapsule Solution Containing Electron-donating Dye Precursor As an electron-donating dye precursor whose coloring material is black, 3
-Diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluorane (32 parts) was added to 1- (3,4
-Dimethylphenyl) -1-phenylethane, and dissolved in 128 parts of diphenylmethane-4,4'-diisocyanate and 1,2-bis {p- (p-isocyanatobenzyl) phenylaminocarbonyloxy} ethane.
40 parts of one mixture and 20 parts of ethyl acetate as an auxiliary solvent were added and uniformly dissolved. This solution was mixed with 160 parts of a 5% aqueous solution of polyvinyl alcohol, and mixed with a homomixer.
The emulsion was dispersed at 5 ° C. to obtain an emulsion having an average particle size of 2 μm. An aqueous solution obtained by dissolving 16 parts of diethylenetriamine in 84 parts of distilled water was added to the obtained emulsion, and the mixture was stirred at 80 ° C.
Heating was performed for 3 hours to obtain a microcapsule liquid.

B. Preparation of heat-sensitive recording material As a reddish electron-donating dye precursor,
Diethylamino-6-chloro-7-methylfluoran 1
5 parts were pulverized with a paint conditioner together with 35 parts of a 2% aqueous solution of polyvinyl alcohol to obtain a dye precursor dispersion. Next, the electron-accepting developer 1,1-bis (4-
(Hydroxyphenyl) cyclohexane 150 parts with a 2% aqueous polyvinyl alcohol solution and 350 parts of a developer dispersion obtained by pulverizing with a paint conditioner, and 150 parts of a sensitizer m-terphenyl with 350 parts of a 2% aqueous polyvinyl alcohol solution. A sensitizer dispersion obtained by pulverizing with a paint conditioner, a calcium carbonate dispersion having a volume average particle diameter of 1 μm obtained by dispersing 5 parts of calcium carbonate with 10 parts of a 2% aqueous sodium hexametaphosphate solution using a homogenizer, . After adding the microcapsule solution obtained in the above, 500 parts of a 10% aqueous solution of polyvinyl alcohol, and 620 parts of water, the mixture was sufficiently stirred to obtain a coating liquid for forming a heat-sensitive recording layer which developed two colors. This coating solution was applied to both sides of the paper support obtained in (1) using an air knife coater so that the coating amount of the solid content was 8.0 g / m ^2, and dried in an oven at 60 ° C. Thus, a heat-sensitive recording material of the present invention was obtained.

Example 2 Production of a heat-sensitive recording material capable of obtaining a color image having absorption in the near infrared region and a color image having substantially no absorption in the near infrared region on both surfaces of the opaque support by heating A. Preparation of Electron Donating Dye Precursor Particles Provided with Color Controlling Layer 3,6-bis (dimethylamino) fluorene-9-
Spiro-3 '-(6'-dimethylamino) phthalide 25
And 2.5 parts of a polyvinyl alcohol aqueous solution (450 parts) with a ball mill to obtain a dispersion having a volume average particle diameter of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 20 parts of methyl methacrylate, which is a compound having an unsaturated carbon bond, was added, and the temperature was raised to 70 ° C. while stirring. To this, 0.2 part of potassium persulfate as a polymerization initiator was added, and polymerization was carried out for 6 hours while stirring was continued. Next, this was cooled to room temperature to obtain a dispersion of electron-donating dye precursor particles having a color-developing layer on the surface.

B. Preparation of Thermosensitive Recording Material As an electron-donating dye precursor in which the color former has absorption in the visible light region and does not have absorption in the near-infrared region, 3-di-n-butylamino-6-type in which the color former is black is used. 25 parts of methyl-7-anilinofluoran were ground together with 80 parts of a 2.5% aqueous solution of polyvinyl alcohol in a ball mill for 24 hours to obtain an electron-donating compound dispersion. Next, 40 parts of 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone as an electron accepting developer was ground with a ball mill for 24 hours together with 60 parts of a 2.5% aqueous solution of polyvinyl alcohol to prepare a dispersion of the electron accepting compound. Obtained. 55 parts of 2-benzyloxynaphthalene as a sensitizer were ground together with 120 parts of a 2.5% aqueous solution of polyvinyl alcohol in a ball mill for 24 hours to obtain a sensitizer dispersion. These three dispersions, and a calcium carbonate dispersion having a volume average particle diameter of 1 μm obtained by dispersing 5 parts of calcium carbonate with 10 parts of a 2% aqueous sodium hexametaphosphate solution using a homogenizer, and further providing the above-described coloring control layer Coating liquid for forming a heat-sensitive recording layer that can obtain a color image having absorption in the near infrared and a color image having substantially no absorption in the near infrared by mixing the dispersion liquid of the electron donor dye precursor particles. I got This coating liquid is applied to both sides of a high-quality paper as an opaque support having a thickness of 55 μm using an air knife coater so that the solid coating amount is 5 g / m ^2, and dried in an oven at 60 ° C. Thus, a heat-sensitive recording material of the present invention was obtained.

Example 3 Production of a heat-sensitive recording material in which one side of an opaque support develops two colors of black and red by heating and the other side of the support develops a black color. A. Preparation of Electron-donating Dye Precursor Particles Provided with Color-Controlling Layer
25 parts of di-n-butylamino-6-methyl-7-anilinofluorane was added to a 2.5% aqueous solution of polyvinyl alcohol 4
Pulverized with a ball mill together with 50 parts, volume average particle size 1 μm
Was obtained. Next, this dispersion was transferred to a polymerization vessel, and 20 parts of methyl methacrylate, which is a compound having an unsaturated carbon bond, was added, and the temperature was raised to 70 ° C. while stirring. To this, 0.2 part of potassium persulfate as a polymerization initiator was added, and polymerization was carried out for 6 hours while stirring was continued. Then
This was cooled to room temperature to obtain a dispersion of electron-donating dye precursor particles having a color-developing layer on the surface.

B. Preparation of heat-sensitive recording material As an electron-donating dye precursor whose coloring material is red, 3
-Diethylamino-6-chloro-7-methylfluorane (25 parts) was pulverized with a 2.5% aqueous polyvinyl alcohol solution (80 parts) in a ball mill for 24 hours to obtain an electron-donating dye precursor dispersion. Then, as an electron-accepting developer,
40 parts of 3'-diallyl-4,4'-dihydroxydiphenylsulfone in 2.5% aqueous polyvinyl alcohol
The mixture was pulverized with 60 parts by a ball mill for 24 hours to obtain an electron-accepting developer dispersion. 55 parts of 2-benzyloxynaphthalene as a sensitizer were ground with a ball mill for 24 hours together with 120 parts of a 2.5% aqueous solution of polyvinyl alcohol to obtain a sensitizer dispersion. These three dispersions and 5 parts of calcium carbonate were added to a 2% aqueous sodium hexametaphosphate solution 10
And a calcium carbonate dispersion having a volume average particle diameter of 1 μm obtained by dispersing with a homogenizer together with a dispersion of electron-donating dye precursor particles provided with the above-described color-developing layer, to form two colors. A coating liquid for forming a heat-sensitive recording layer was obtained. This coating liquid was applied to one surface of a high-quality paper as an opaque support having a thickness of 55 μm using an air knife coater so that the solid content was 5 g / m ^2, and an oven at 60 ° C. And dried.

Next, 25 parts of 3-di-n-butylamino-6-methyl-7-anilinofluorane as an electron-donating dye precursor having a black color is 2.5% aqueous solution of 2.5% polyvinyl alcohol. And an electron-donating dye precursor dispersion obtained by pulverizing with a ball mill for 24 hours, and 40 parts of 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone as an electron-accepting developer in 2.5 parts. Electron-accepting developer dispersion obtained by pulverizing in a ball mill for 24 hours together with 60 parts of a 50% aqueous solution of polyvinyl alcohol, 55 parts of 2-benzyloxynaphthalene as a sensitizer and 120 parts of a 2.5% aqueous solution of polyvinyl alcohol in a ball mill. A sensitizer dispersion obtained by grinding for 24 hours, and 5 parts of calcium carbonate were homogenized with 10 parts of a 2% aqueous sodium hexametaphosphate solution. Thoroughly stirred after mixing the resulting calcium carbonate dispersion was dispersed by homogenizer, to obtain a heat-sensitive recording layer forming coating solution for colored blackish. The coating liquid was coated on one side of the high-quality paper, which is an opaque support coated on one side, with an air knife coater so that the solid content was 5 g / m ^2. Then, the resultant was dried in an oven at 60 ° C. to obtain a heat-sensitive recording material of the present invention.

Example 4 By heating, one surface of the support developed into two colors of yellow and black.
Preparation of a thermosensitive recording material in which the other side develops two colors of red and purple. As an electron-donating dye precursor whose color former is black,
Dye precursor dispersion obtained by pulverizing 15 parts of 3-dibutylamino-6-methyl-7-anilinofluoran together with 40 parts of a 2% aqueous polyvinyl alcohol solution using a paint conditioner, and 1, 1 as an electron-accepting developer. Service (4-
(Hydroxyphenyl) cyclohexane 25 parts of a 2% aqueous polyvinyl alcohol solution and 60 parts of an aqueous polyvinyl alcohol solution were pulverized with a paint conditioner to obtain an electron-accepting developer dispersion. A heat-fusible compound dispersion obtained by pulverizing with a paint conditioner together with 100 parts of an aqueous solution, and 70 parts of calcium carbonate well dispersed with 100 parts of a 0.5% polyvinyl alcohol aqueous solution using a homogenizer to obtain a volume average. After mixing a calcium carbonate dispersion having a particle size of 1 μm, the mixture was sufficiently stirred to obtain a coating liquid for forming a heat-sensitive recording layer which developed black. As an electron-donating dye precursor in which the color former is yellow,
Dye precursor dispersion obtained by pulverizing 15 parts of 3,6-dimethoxyfluoran together with 40 parts of a 2% aqueous polyvinyl alcohol solution using a paint conditioner, and 1,1-bis (4-hydroxyphenyl) cyclohexane as an electron accepting developer 25 parts of 2% polyvinyl alcohol aqueous solution 60
Of the electron-accepting developer dispersion obtained by pulverizing with a paint conditioner together with 40 parts of 2-benzyloxynaphthalene as a heat-fusible compound together with 100 parts of a 2% aqueous solution of polyvinyl alcohol using a paint conditioner. The fusible compound dispersion was obtained by well dispersing 70 parts of calcium carbonate with 100 parts of a 0.5% aqueous polyvinyl alcohol solution using a homogenizer.
After mixing a calcium carbonate dispersion having a volume average particle diameter of 1 μm, the mixture was sufficiently stirred to obtain a coating liquid for forming a heat-sensitive recording layer which developed yellow.

As an electron-donating dye precursor having a blue color group, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -7- A dye precursor dispersion obtained by pulverizing 15 parts of azaphthalide with 40 parts of a 2% aqueous polyvinyl alcohol solution using a paint conditioner, 25 parts of 1,1-bis (4-hydroxyphenyl) cyclohexane as an electron-accepting developer and 2% polyvinyl alcohol Alcohol aqueous solution 6
Electron-accepting developer dispersion obtained by pulverizing with a paint conditioner together with 0 part, and 40 parts of 2-benzyloxynaphthalene as a heat-fusible compound were pulverized with a paint conditioner together with 100 parts of a 2% aqueous solution of polyvinyl alcohol. A heat-fusible compound dispersion and 70 parts of calcium carbonate in a 0.5% aqueous polyvinyl alcohol solution 100
A calcium carbonate dispersion having a volume average particle diameter of 1 μm obtained by well-dispersing using a homogenizer together with the portion was mixed and sufficiently stirred to obtain a coating liquid for forming a heat-sensitive recording layer which developed a blue color.

As a reddish electron-donating dye precursor, 15 parts of 3-diethylamino-6-chloro-7-methylfluoran were obtained by pulverizing with a paint conditioner together with 40 parts of a 2% aqueous solution of polyvinyl alcohol. Dye precursor dispersion, Electron accepting developer dispersion obtained by pulverizing 25 parts of 1,1-bis (4-hydroxyphenyl) cyclohexane with 60 parts of a 2% aqueous solution of polyvinyl alcohol with a paint conditioner as an electron accepting developer. Liquid, a heat-fusible compound dispersion obtained by pulverizing 40 parts of 2-benzyloxynaphthalene as a heat-fusible compound with 100 parts of a 2% aqueous polyvinyl alcohol solution by a paint conditioner, and 70 parts of calcium carbonate in 0.5 part
Volume average particle diameter obtained by well-dispersing with a homogenizer together with 100 parts of a 100% aqueous solution of polyvinyl alcohol.
After mixing the μm calcium carbonate dispersion, the mixture was stirred well,
A coating liquid for forming a heat-sensitive recording layer that develops a red color was obtained. Is coated on one surface of a high-quality paper as an opaque support having a thickness of 55 μm using an air knife coater so that the coating amount of each solid is 5 g / m ^2. After the work, the material was dried in an oven at 60 ° C. to obtain a heat-sensitive recording material. Further, the coating liquid obtained in the above was coated on the other surface of the high-quality paper using an air knife coater such that the solid coating amount was 5 g / m ^2. The resultant was dried in an oven at ℃ to obtain a heat-sensitive recording material of the present invention.

Example 5 By heating, a color image having absorption in near infrared and a color image having substantially no absorption in near infrared were obtained on one surface of the opaque support. Preparation of a heat-sensitive recording material capable of obtaining a black color image on one side. A. Preparation of Electron Donating Dye Precursor Particles Provided with Color Controlling Layer 3,6-bis (dimethylamino) fluorene-9-
Spiro-3 '-(6'-dimethylamino) phthalide 25
And 2.5 parts of a polyvinyl alcohol aqueous solution (450 parts) with a ball mill to obtain a dispersion having a volume average particle diameter of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 20 parts of methyl methacrylate, which is a compound having an unsaturated carbon bond, was added, and the temperature was raised to 70 ° C. while stirring. To this, 0.2 part of potassium persulfate as a polymerization initiator was added, and polymerization was carried out for 6 hours while stirring was continued. Next, this was cooled to room temperature to obtain a dispersion of electron-donating dye precursor particles having a color-developing layer on the surface.

B. Preparation of Thermosensitive Recording Material As an electron-donating dye precursor in which the color former has absorption in the visible light region and does not have absorption in the near-infrared region, 3-di-n-butylamino-6-type in which the color former is black is used. 25 parts of methyl-7-anilinofluoran were ground together with 80 parts of a 2.5% aqueous solution of polyvinyl alcohol in a ball mill for 24 hours to obtain an electron-donating compound dispersion. Next, 40 parts of 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone as an electron accepting developer was ground with a ball mill for 24 hours together with 60 parts of a 2.5% aqueous solution of polyvinyl alcohol to prepare a dispersion of the electron accepting compound. Obtained. 55 parts of 2-benzyloxynaphthalene as a sensitizer was ground with a 2.5% aqueous polyvinyl alcohol solution (120 parts) in a ball mill for 24 hours.
A sensitizer dispersion was obtained. These three dispersions, and a calcium carbonate dispersion having a volume average particle diameter of 1 μm obtained by dispersing 5 parts of calcium carbonate with 10 parts of a 2% aqueous sodium hexametaphosphate solution using a homogenizer, Mixing the dispersion of the electron-donating dye precursor particles provided with the color control layer obtained in the above, and a color image having absorption in the near infrared,
A coating liquid for forming a heat-sensitive recording layer capable of obtaining a black color-developed image substantially having no absorption in the near infrared was obtained. This coating solution was coated on one side of a high-quality paper as an opaque support having a thickness of 55 μm using an air knife coater to obtain a solid coating amount of 5 g / m 2.
Coating was carried out so as to be ² and dried in an oven at 60 ° C.

Next, 25 parts of 3-di-n-butylamino-6-methyl-7-anilinofluoran was used as an electron-donating dye precursor having a black color system as a 2.5% aqueous solution of 2.5% polyvinyl alcohol. And an electron-donating dye precursor dispersion obtained by pulverizing with a ball mill for 24 hours, and 40 parts of 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone as an electron-accepting developer in 2.5 parts. Electron-accepting developer dispersion obtained by pulverizing in a ball mill for 24 hours together with 60 parts of a 50% aqueous solution of polyvinyl alcohol, 55 parts of 2-benzyloxynaphthalene as a sensitizer and 120 parts of a 2.5% aqueous solution of polyvinyl alcohol in a ball mill. A sensitizer dispersion obtained by grinding for 24 hours, and 5 parts of calcium carbonate were homogenized with 10 parts of a 2% aqueous sodium hexametaphosphate solution. Obtained by dispersing in homogenizer, thoroughly stirred after mixing the calcium carbonate dispersion having a volume average particle size of 1 [mu] m, to obtain a heat-sensitive recording layer forming coating solution for colored blackish. This coating liquid was applied to the other surface of the high-quality paper coated on one side using an air knife coater so that the coating amount of the solid content was 5 g / m ² , To obtain a heat-sensitive recording material of the present invention.

Example 6 By heating, a color image having absorption in the near infrared region and a color image having substantially no absorption in the near infrared region were obtained on one surface of the opaque support. Preparation of a heat-sensitive recording material capable of obtaining two color images of red and black on one surface. A. Preparation of Electron Donating Dye Precursor Particles Provided with Color Controlling Layer 3,6-bis (dimethylamino) fluorene-9-
Spiro-3 '-(6'-dimethylamino) phthalide 25
And 2.5 parts of a polyvinyl alcohol aqueous solution (450 parts) with a ball mill to obtain a dispersion having a volume average particle diameter of 1 μm. Next, this dispersion was transferred to a polymerization vessel, and 20 parts of methyl methacrylate, which is a compound having an unsaturated carbon bond, was added, and the temperature was raised to 70 ° C. while stirring. To this, 0.2 part of potassium persulfate as a polymerization initiator was added, and polymerization was carried out for 6 hours while stirring was continued. Next, this was cooled to room temperature to obtain a dispersion of electron-donating dye precursor particles having a color-developing layer on the surface.

B. Preparation of Thermosensitive Recording Material As an electron-donating dye precursor in which the color former has absorption in the visible light region and does not have absorption in the near-infrared region, 3-di-n-butylamino-6-type in which the color former is black is used. 25 parts of methyl-7-anilinofluoran were ground together with 80 parts of a 2.5% aqueous solution of polyvinyl alcohol in a ball mill for 24 hours to obtain an electron-donating compound dispersion. Next, 40 parts of 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone as an electron accepting developer was ground with a ball mill for 24 hours together with 60 parts of a 2.5% aqueous solution of polyvinyl alcohol to prepare a dispersion of the electron accepting compound. Obtained. 55 parts of 2-benzyloxynaphthalene as a sensitizer were ground together with 120 parts of a 2.5% aqueous solution of polyvinyl alcohol in a ball mill for 24 hours to obtain a sensitizer dispersion. These three dispersions, and a calcium carbonate dispersion having a volume average particle diameter of 1 μm obtained by dispersing 5 parts of calcium carbonate with 10 parts of a 2% aqueous sodium hexametaphosphate solution using a homogenizer, A dispersion of electron-donating dye precursor particles provided with a color-developing layer obtained in the above is mixed, and a color image having absorption in the near infrared and a black color image having substantially no absorption in the near infrared Was obtained to obtain a thermosensitive recording layer forming coating liquid. This coating solution was coated on one side of a high-quality paper as an opaque support having a thickness of 55 μm using an air knife coater to obtain a solid coating amount of 5 g / m 2.
Coating was carried out so as to be ² and dried in an oven at 60 ° C.

C. Preparation of Electron-donating Dye Precursor Particles Provided with Color-Controlling Layer
25 parts of di-n-butylamino-6-methyl-7-anilinofluorane was added to a 2.5% aqueous solution of polyvinyl alcohol 4
Pulverized with a ball mill together with 50 parts, volume average particle size 1 μm
Was obtained. Next, this dispersion was transferred to a polymerization vessel, and 20 parts of methyl methacrylate, which is a compound having an unsaturated carbon bond, was added, and the temperature was raised to 70 ° C. while stirring. To this, 0.2 part of potassium persulfate as a polymerization initiator was added, and polymerization was carried out for 6 hours while stirring was continued. Then
This was cooled to room temperature to obtain a dispersion of electron-donating dye precursor particles having a color-developing layer on the surface.

D. Preparation of heat-sensitive recording material As a reddish electron-donating dye precursor,
Diethylamino-6-chloro-7-methylfluoran 2
5 parts were ground with a ball mill for 24 hours together with 80 parts of a 2.5% aqueous solution of polyvinyl alcohol to obtain an electron-donating dye precursor dispersion. Next, 3,3 'is used as an electron accepting developer.
40 parts of diallyl-4,4'-dihydroxydiphenylsulfone in 2.5% aqueous polyvinyl alcohol solution 60
The resulting mixture was ground with a ball mill for 24 hours to obtain an electron-accepting developer dispersion. 55 parts of 2-benzyloxynaphthalene as a sensitizer in 2.5% aqueous polyvinyl alcohol 1
20 parts together with a ball mill for 24 hours to obtain a sensitizer dispersion. These three dispersions, and a calcium carbonate dispersion having a volume average particle diameter of 1 μm obtained by dispersing 5 parts of calcium carbonate with 10 parts of a 2% aqueous sodium hexametaphosphate solution using a homogenizer; The dispersion liquid of the electron-donating dye precursor particles provided with the color-developing layer obtained in the above was mixed to obtain a coating liquid for forming a heat-sensitive recording layer which developed two colors. This coating solution was applied to B.I. The other side of the high-quality paper coated on one side obtained in the above was coated using an air knife coater so that the solid content was 5 g / m ^2, and dried in an oven at 60 ° C. Thus, a heat-sensitive recording material of the present invention was obtained.

Comparative Example 1 In Example 1, a biaxially stretched transparent polyethylene terephthalate film having a thickness of 75 μm was used instead of using the paper support obtained in (1) Preparation of opaque support. Except for the above, a heat-sensitive recording material was obtained in exactly the same manner as in Example 1.

Comparative Example 2 As an electron-donating dye precursor whose color former is black, 3
Dye precursor dispersion obtained by pulverizing 15 parts of -dibutylamino-6-methyl-7-anilinofluoran together with 40 parts of a 2% aqueous polyvinyl alcohol solution using a paint conditioner, and 1,1-bis as an electron-accepting developer. (4-Hydroxyphenyl) cyclohexane 25 parts of a 2% aqueous solution of polyvinyl alcohol was pulverized with a paint conditioner to obtain an electron-accepting developer dispersion, and 40 parts of 2-benzyloxynaphthalene as a heat-fusible compound were added. A heat fusible compound dispersion obtained by pulverizing with a paint conditioner together with 100 parts of an aqueous solution of 100% polyvinyl alcohol, and 70 parts of calcium carbonate obtained by well-dispersing with 100 parts of an aqueous solution of 0.5% polyvinyl alcohol using a homogenizer. Mix calcium carbonate dispersion with volume average particle size 1μm Thoroughly stirred after, to obtain a heat-sensitive recording layer forming coating solution for colored black. Apply the obtained coating liquid to a thickness of 5
Using a air knife coater on both sides of a general high-quality paper as an opaque support having a thickness of 5 μm, each solid coating amount was 5 g.
/ M ² and dried in an oven at 60 ° C. to obtain a heat-sensitive recording material.

Test and Evaluation Both surfaces of the heat-sensitive recording materials obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were applied with a G3 facsimile printing tester at an applied voltage of 26 V and an energizing time of 0.6 ms. Printing under the low energy condition of
V, and printing was performed under high energy conditions with an energization time of 0.9 millisecond. In each of the obtained images, each hue was observed with the naked eye.
Table 1 shows the results. In each of the obtained images, the absorbance at 780 nm, which is a near-infrared light region, was also measured. An image in which an extremely strong absorbance of 0.8 or more was recognized was indicated as "near" in the hue column of the image in the table. On the other hand, when the absorbance was 0.1 or less and the absorption at 780 nm was hardly recognized, no display was made.

Regarding the discriminability of information, it is possible to discriminate information by the difference in hue of the obtained images or by the optical difference. The points are shown in Table 1. The larger the discrimination point, the better the discrimination of information.

Regarding the anti-counterfeiting property, the anti-counterfeiting effect can be obtained even if the obtained images have different hues. As a result, it is possible to print the secret information as an image that cannot be visually distinguished in advance. That is, when optically different images are used, an extremely high forgery prevention effect can be obtained. Therefore, the number of images having different hues and the number of optically different images are added together, and when an optically different image is obtained, a value obtained by adding one point is shown in Table 1 as a forgery prevention point. . The greater the anti-counterfeiting points, the better the anti-counterfeiting properties.

[0116]

[Table 1]

As is clear from Table 1, by printing information on both sides, it is possible to increase the amount of information and at the same time improve the discrimination of information. Also, by increasing the number of hues in the resulting image, anti-counterfeiting is improved. Furthermore, it can be seen that the use of an image having absorption in the near-infrared region significantly improves the forgery prevention. In Comparative Example 1, since the support was transparent, the information on the back surface could be seen from the front. Therefore, when independent information is printed on the front and back sides, when viewed from the front side, the image on the front side and the image on the back side overlap, making it difficult to read the individual information. Was difficult.

[0118]

According to the present invention, at least one heat-sensitive recording layer, which is usually colorless and develops two or more hues upon heating, is provided on one surface of the opaque support, and the other surface is provided with at least one heat-sensitive recording layer. By providing at least one heat-sensitive recording layer that is colorless and develops one or more hues by heating, a heat-sensitive recording material that has a large amount of information per unit area and has a single-colored front and back color in the same hue As compared with the above, it becomes possible to obtain a heat-sensitive recording material having improved discrimination and forgery prevention. In addition, by making at least one of the coloring hues a black hue, versatility is improved. Further, by adopting a heat-sensitive recording layer having a structure capable of obtaining a color image having absorption in near infrared and a color image having substantially no absorption in near infrared, anti-counterfeiting property is further improved.

Claims (9)

[Claims] 1. A heat-sensitive recording material comprising at least one heat-sensitive recording layer which develops two or more colors by heating on both surfaces of an opaque support. 2. At least one color hue of at least one heat-sensitive recording layer that develops at least two colors provided on one surface of an opaque support has at least one color hue. 2. The color hue of at least one or more of the color hues of at least one or more thermosensitive recording layers that develops at least two hues provided on the other surface. Thermal recording material. 3. The color hues of at least one heat-sensitive recording layer which develops two or more hues provided on one surface of an opaque support are provided on the other surface of the support. 2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer is different from at least one of the heat-sensitive recording layers that develops at least one kind of hue. 4. The color hue of at least one heat-sensitive recording layer which develops at least two colors provided on one surface of an opaque support, wherein one color hue is black. 3. The heat-sensitive recording material according to claim 1, wherein 5. An opaque support is provided with at least one heat-sensitive recording layer that develops two or more hues on one surface, and develops only one hue on the other surface of the support. A heat-sensitive recording material comprising a heat-sensitive recording layer. 6. A color image having absorption in the near infrared region and a color image having substantially no absorption in the near infrared region can be formed on both surfaces of the opaque support by heating.
A thermosensitive recording material comprising at least two thermosensitive recording layers. 7. At least one layer capable of forming a color image having absorption in the near infrared region and a color image having substantially no absorption in the near infrared region on one surface of the opaque support by heating. A heat-sensitive recording material, comprising: a heat-sensitive recording layer that develops only one type of hue on the other surface of the support. 8. An opaque support is provided with at least one heat-sensitive recording layer which develops two or more colors by heating on one surface of the opaque support, and has an absorption in the near infrared region by heating on the other surface. A thermosensitive recording material comprising at least one thermosensitive recording layer capable of forming a color image and a color image having substantially no absorption in the near infrared region. 9. A form of a particle having at least one of two or more coloring components contained in the heat-sensitive recording layer provided with a coloring control layer obtained by polymerizing a compound having an unsaturated carbon bond on the surface thereof. 9. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer is contained in the heat-sensitive recording layer.