JPH11277906A - Thermal recording material - Google Patents

Abstract

(57) [Problem] To provide a heat-sensitive recording material having high preservability of an image area, particularly excellent in oil resistance and plasticizer resistance. SOLUTION: In a heat-sensitive recording material having a heat-sensitive coloring layer mainly composed of a leuco dye and a color developing agent for coloring the leuco dye upon heating on a support, an aromatic compound having an acidic functional group as a substituent is provided. Two sulfonyl groups per molecule
A heat-sensitive recording material comprising at least one compound having at least one compound.

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 having excellent image storability.

[0002]

2. Description of the Related Art A thermosensitive recording material generally comprises a support provided with a thermosensitive recording layer mainly composed of an electron-donating colorless or light-colored dye precursor and an electron-accepting developer. By heating with a head, hot pen, laser light, etc.,
A dye precursor and a developer react instantaneously to obtain a recorded image. Japanese Patent Publication No. 43-4160, Japanese Patent Publication No. Sho 4
It is disclosed in JP-A-5-14039. Such a heat-sensitive recording material has advantages such that recording can be obtained with a relatively simple device, maintenance is easy, and noise is less generated.In recent years, computers, facsimile machines, ticket vending machines, label printers, It is used in a wide range of fields as a recording material for recorders and the like. A heat-sensitive recording material using such an electron-donating dye precursor and an electron-accepting color developer has excellent properties such as good appearance, good feel, high color density, and the like, but the recorded image The part is easily recorded by contacting with plastics such as polyvinyl chloride, discoloring with plasticizers and additives contained in plastics, or contacting with chemicals contained in foods, cosmetics, etc. There has been a drawback that the storability as a recording material is inferior, for example, the image portion is erased or the background portion is colored.

[0003] The use of highly reliable color developers as means for achieving high storage stability of recorded images has been clarified. For example, the use of a phenol sulfone compound in JP-A-58-82788 and JP-A-60-13852 and the use of a metal benzoate in JP-A-61-47292 are disclosed in 62-169
No. 681 proposes to use a substituted salicylic acid compound, but when these compounds are used as a color developer, the fastness of an image area to a plasticizer is insufficient.

Japanese Patent Application Laid-Open No. Sho 62-80089 discloses a heat-sensitive recording material using a nitrophthalic acid monoester compound, but this type is also insufficient in terms of fastness to a plasticizer in an image area. Was. Further, Japanese Unexamined Patent Publication No.
Japanese Patent Application Laid-Open No. 255262/1990 proposes a compound using a compound containing a sulfonylurea group, but this type has a disadvantage in that the fastness to the plasticizer in the image area is excellent, but the color sensitivity is extremely poor. I have.

Japanese Patent Application Laid-Open No. 9-267566 proposes to use a diamic acid derivative and a metal salt thereof. However, these compounds cause the image area to be largely decolorized under a high temperature environment. It has the disadvantage that

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material having high preservability of an image area, particularly excellent in oil resistance and plasticizer resistance in view of the above-mentioned prior art. I do.

[0007]

According to the present invention, there is provided a thermosensitive recording material having a thermosensitive coloring layer containing a leuco dye and a developer for developing the leuco dye upon heating on a support. A thermosensitive recording material, characterized by using at least one compound having two or more aromatic sulfonyl groups having one or more functional groups as substituents in one molecule. The present invention further provides a thermosensitive recording material, wherein the acidic group of the developer compound is a carboxyl group. Further, there is provided a heat-sensitive recording material characterized by providing an undercoat layer containing plastic spherical hollow fine particles between a support and a heat-sensitive recording layer.

The compound having two or more aromatic sulfonyl groups having one or more acidic functional groups as substituents in one molecule used in the present invention can be more specifically represented by the following general formula (I).

[0009]

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In the general formula (I), X is -OYO-
And a divalent functional group represented by a -NHYHN- group. Here, the divalent functional group represented by Y includes a carbonyl group, a sulfonyl group, a divalent group derived from an aliphatic hydrocarbon, one or more hetero atoms in the main chain, a carbonyl group, and a sulfonyl group. , Ester bond, divalent group derived from aliphatic hydrocarbon containing aromatic ring, one or more heteroatoms, carbonyl group, sulfonyl group, ester bond, alkylene, fat containing heteroatom in main chain And a divalent group derived from two aromatic hydrocarbons linked by an aromatic hydrocarbon.

A represents an acidic functional group having the functions of a Bronsted acid and a Lewis acid, and specifically represents a carboxyl group, a hydroxyl group, a urea group, a sulfonylurea group, an amide group and the like. Hydroxyl groups are preferred.

The compound represented by the general formula (I) is a completely new compound. The reason why the heat-sensitive recording material using these compounds has high plasticizer resistance is not clear, but it is considered that the following factors generally contribute. When two or more aromatic carboxylic acids are contained in one molecule, the molecular weight increases, and the solubility in the plasticizer decreases. By having two or more aromatic carboxylic acids in one molecule, it has a three-dimensional size that wraps around the dye. The presence of the electron-donating substituent increases the affinity for the dye.

Further, preferred examples of the compound of the present invention having two or more aromatic sulfonyl groups having one or more acidic functional groups as substituents in one molecule are represented by formulas (II) and (I).
The compound represented by II) is mentioned.

[0014]

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[0015]

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In the general formulas (II) and (III), X
Represents a divalent functional group represented by -OYO- and -NHYHN- groups. Here, the divalent functional group represented by Y includes a carbonyl group, a sulfonyl group, a divalent group derived from an aliphatic hydrocarbon, one or more hetero atoms in the main chain, a carbonyl group, and a sulfonyl group. , Ester bond, divalent group derived from aliphatic hydrocarbon containing aromatic ring, one or more heteroatoms, carbonyl group, sulfonyl group, ester bond, alkylene, fat containing heteroatom in main chain And a divalent group derived from two aromatic hydrocarbons linked by an aromatic hydrocarbon.

Specific examples of X include -OAO- (A is an alkylene having 1 to 8 carbon atoms,
Oxoalkylene, bisoxoalkylene, trisoxoalkylene, xylylene, phenylene, biphenylene, substituted biphenylene, naphthylene,

[0018]

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-NHBNH- (B is alkylene having 1 to 8 carbon atoms, oxoalkylene, phenylene, xylylene, biphenylene, substituted biphenylene, naphthylene,

[0020]

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Further, in the general formula (II), more preferable compounds include the compounds represented by the general formulas (IV) and (V).

[0022]

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[0023]

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Specific examples are shown in Tables 1 and 2 below, but are not necessarily limited to these. The numbers in the table represent compound numbers.

[0025]

[Table 1-1]

[0026]

[Table 1-2]

[0027]

[Table 1-3]

[0028]

[Table 2]

The undercoat layer used in the present invention is composed mainly of hollow spherical plastic particles. The hollow spherical plastic particles are made of a thermoplastic polymer as a shell and contain air or other gas inside. These are plastic spherical hollow fine particles already in a foamed state, and have an average particle size of about 0.2 to 20 μm. If the average particle size is smaller than 0.2 μm, there is a problem in terms of cost due to the problem of productivity such as difficulty in obtaining an arbitrary hollowness. Conversely, if the average particle size is 20 μm or more, the smoothness after coating and drying is reduced. Therefore, the contact property with the thermal head is deteriorated, and the thermal sensitivity improving characteristic cannot be exhibited. Further, the plastic spherical hollow fine particles used in the present invention,
The hollowness is 40% or more.
%, The thermal insulation from the thermal head is released through the support to the outside of the heat-sensitive recording material, and the effect of improving the thermal sensitivity becomes insufficient. Here, the hollowness is a ratio of the outer diameter to the inner diameter of the hollow particles, and is represented by the following equation. Hollowness (%) = (inner diameter of hollow particles / outer diameter of hollow particles) ×
100

The plastic spherical hollow fine particles used in the present invention can be easily and inexpensively produced from an acrylic resin such as acrylate or acrylonitrile, a styrene resin such as styrene, or a copolymer resin thereof.

As the basic dye precursor used in the present invention, a leuco dye is used, and examples thereof include the following. 3,3-bis (P-dimethylaminophenyl) phthalide, 3,3-bis (P-dimethylaminophenyl) -6
-Dimethylaminophthalide, 3-diethylamino-6-
Methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N-butylamino-6-methyl-7-anilinofluoran, 3-N -Ethyl-N-p-tolylamino-6-
Methyl-7-anilinofluoran, 3-N-methyl-N
-Propylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-propylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N-amylamino-6-methyl -7-anilinofluoran, 3-
N-ethyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-isoamylamino-6-methyl-7-anilinofluoran, 3-N-hexyl-N-isoamyl Amino-6-methyl-7-anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-N
-Ethyl-N-furanylmethylamino-6-methyl-7
-Anilinofluoran, 3-diethyl-N-butylamino-7- (2'-fluoroanilino) fluoran, 3-
Pyrrolidyl-7-dibenzylaminofluoran, 3-
Bis (diphenylamino) fluoran, 3-diethylamino-7- (2′-chloroanilino) fluoran, 3-
Diethylamino-6-chloro-7-anilinofluoran, 3-dibutylamino-7- (2'-chloroanilino) fluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluor Oran, 3-N-methyl-N-cyclohexylamino-6-chlorofluoran, 3-diethylamino-6
Methyl-7- (2 ′, 4′-dimethylanilino) fluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-butylamino-7- (2′-chloroanilino) fluoran, 3-diethylamino-6 Ethoxyethyl-7-anilinofluoran and the like.

In the present invention, in addition to being used as a color developer, it can be used in combination with a conventionally known color developer and used for other purposes such as a sensitizer. Specific examples of conventionally known color developers used at that time include the following. 4,4'-isopropylidenebisphenol, 4,4 '
Isopropylidenebis (o-methylphenol),
4,4′-sec-butylidenebisphenol, 4,
4'-isopropylidenebis (2-terbutylphenol), zinc p-nitrobenzoate, 1,3,5-tris (4-terbutyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid, 2,2 -(3,4-dihydroxyphenylpropane), bis (4-hydroxy-
3-methylphenyl sulfide), 4- {β- (p-methoxyphenoxy) ethoxy} salicylic acid, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, monobenzyl phthalate monocarboxylic acid Acid, 4,4′-cyclohexylidenebisphenol,
4,4′-isopropylidenebis (2-chlorophenol), 2,2′-methylenebis (4-methyl-6-te
rbutylphenol), 4,4'-butylidenebis (6
-Terbutyl-2-methyl) phenol, 1,1,3
-Tris (2-methyl-4-hydroxy-5-cyclohexyl) butane, 4,4'-thiobis (6-terbutyl-2-methylphenol), 4,4'-diphenolsulfone, 4-benzyloxy-4 '-Hydroxydiphenylsulfone, 4-isopropyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide, 2,4'-diphenolsulfoxide, P
Isopropyl hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) -2 -Hydroxypropane, N, N-diphenylthiourea, N, N-di (m-chlorophenylthiourea), salicylanilide, 5-chlorosalicylanilide, bis (4-hydroxyphenyl) acetic acid methyl ester, bis (4-hydroxy Phenyl) acetic acid benzyl ester, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene,
2,4'-diphenol sulfone, 2,2'-diallyl-4,4'-diphenol sulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone, α, α-bis (4-hydroxyphenyl)- α-methyltoluene,
4,4′-thiobis (2-methylphenol), 4,
4'-thiobis (2-chlorophenol) and the like.

In the present invention, various heat-fusible substances can be used as a sensitivity improver. Specific examples thereof include the following. Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, zinc stearate, aluminum stearate, calcium stearate, zinc palmitate, and fatty acid metal salts such as zinc behenate; diphenyl sulfone; Diphenylmethane,
p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, 1
-Phenyl-2-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl carbonate,
Benzyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane,
1,2-bis (4-methylphenoxyethane), 1,4
-Diphenoxy-2-butene, 1,2-bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,
4-diphenylthiobutane, 1,4-diphenylthio-
2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, di- Benzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethanol, 1,
1-diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) Propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (oxalate)
-Methylbenzyl), bis (4-chlorobenzyl) oxalate and the like.

In the present invention, the binder resin used for forming the heat-sensitive recording layer is appropriately selected from conventionally known water-soluble polymers and aqueous polymer emulsions. Specific examples thereof include, for example, polyvinyl alcohol, starch, starch derivatives, methoxycellulose, hydroxyethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate,
Polyvinyl pyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkaline salt, isobutylene / maleic anhydride copolymer alkaline salt, polyacrylamide, alginic acid Soda, gelatin, casein and the like. Examples of the aqueous polymer emulsion include latexes such as styrene / butadiene copolymer and styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic copolymer, and styrene / acrylate copolymer. Emulsions such as coalescence, acrylate resin, and polyurethane resin are exemplified.

In the present invention, the binder resin used for forming the undercoat layer is appropriately selected from conventionally known water-soluble polymers or aqueous polymer emulsions. Specific examples thereof include, for example, polyvinyl alcohol, starch, starch derivatives, methoxycellulose,
Cellulose derivatives such as hydroxyethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt , Isobutylene / maleic anhydride copolymer alkali salt polyacrylamide, sodium alginate, gelatin, casein and the like. Examples of the aqueous polymer emulsion include latexes such as styrene / butadiene copolymer and styrene / butadiene / acrylic copolymer, vinyl acetate resin, vinyl acetate / acrylic copolymer, and styrene / acrylate copolymer. Emulsions such as coalescence, acrylate resin, and polyurethane resin are exemplified.

In the present invention, by adding an inorganic pigment as a filler to the undercoat layer in addition to the plastic spherical hollow fine particles, it is possible to improve the contact property with the thermal head. Sensitivity can be further improved. Examples of inorganic pigments include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate,
Clay, talc, kaolin and the like.

Further, in the present invention, together with the leuco dye and the color developer, if necessary, auxiliary components commonly used in this type of heat-sensitive recording material, for example, fillers, surfactants, lubricants, pressure-color-forming inhibitors Can be used in combination. In this case, fillers include calcium carbonate, silica,
Inorganic fine powders such as zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium and silica, urea-formalin resin, styrene / methacrylic acid copolymer Organic fine powders such as a coalesced resin, a polystyrene resin, and a vinylidene chloride resin can be given. Examples of the lubricant include higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, and various animal, vegetable, mineral or petroleum waxes.

Further, the heat-sensitive recording material of the present invention is required on the heat-sensitive recording layer of the present invention for the purpose of improving the head matching property at the time of printing, and improving the writing property and printing property on the recording material. It is also possible to provide a protective layer accordingly, but in this case, the above-mentioned filler, binder, heat-fusible substance and the like can be used as components constituting the protective layer.

In the present invention, when the compounds represented by the general formulas (I) and (II) are used in the heat-sensitive recording layer, the content is 1 to 5 g / m ² , preferably 1 to ² g by dry weight.
/ M ² is appropriate.

The heat-sensitive recording material using the compound of the present invention can be used in any field where a heat-sensitive recording material is conventionally used. To be specific, facsimile paper, food POS label, industrial barcode label, linerless label, ticket paper, ticket paper with magnetism,
There are CAD paper, transparent heat-sensitive film and the like.

[0041]

Next, the present invention will be described in more detail with reference to examples. The following parts and percentages are all based on weight.

(Example 1) A mixture having the following composition was dispersed in a magnetic ball mill to prepare [Solution A] to [Solution E]. [Solution A] 3-N, N dibutylamino-6-methyl-7-anilinofluoran 10 parts 10% aqueous solution of polyvinyl alcohol 10 parts Water 30 parts [Solution B] Compound 10 of compound No. (28) 10 parts 10% polyvinyl Alcohol aqueous solution 10 parts Water 30 parts [liquid C] P527 (silica gel manufactured by Mizusawa Chemical) 10 parts 10% polyvinyl alcohol aqueous solution 10 parts water 30 parts [liquid D] zinc stearate 10 parts 10% polyvinyl alcohol aqueous solution 10 parts water 30 parts

Next, a mixture having the following composition was stirred and dispersed with a disper to prepare [E solution]. [E liquid] Non-foamable plastic micro hollow particles 40 parts (solid content 24%, average particle diameter 3 μm, hollowness 95%) Styrene / butadiene copolymer latex 10 parts Water 50 parts

Next, using [solution A] to [solution E], a coating solution for the thermosensitive coloring layer and a coating solution for the undercoat were prepared at the following mixing ratio. [Coating solution for thermosensitive coloring layer] [Solution A]: [Solution B]: [Solution C]: [Solution D] = 1: 2:
1: 1 [undercoat coating liquid] [liquid E]: [liquid C] = 2: 1 <coating of each layer> (undercoat coating liquid) was applied to the surface of commercially available high-quality paper (basis weight 60 g / m ² ). 3 g / m ² dry weight
And dried to obtain an intermediate coated paper (paper coated with an undercoat layer). On the undercoat layer, a thermosensitive coloring layer coating solution was applied and dried so as to have a dry weight of 2.5 g / m ² to form a thermosensitive coloring layer. Then, 10Kg /
A calendering treatment was performed at a pressure of cm ² to obtain a heat-sensitive recording material of the present invention.

Example 2 A thermosensitive recording was prepared in the same manner as in Example 1 except that the compound No. (29) was used instead of the compound No. (28) in the [solution B] of Example 1. The material was obtained.

Example 3 A thermosensitive recording was prepared in the same manner as in Example 1 except that the compound No. (28) was used in place of the compound No. (28) in the [solution B] of Example 1. The material was obtained.

Example 4 A thermosensitive recording was prepared in the same manner as in Example 1 except that the compound No. (28) was used in place of the compound No. (28) in the [solution B] of Example 1. The material was obtained.

Example 5 A thermosensitive recording was prepared in the same manner as in Example 1 except that the compound No. (28) was used in place of the compound No. (28) in the [solution B] of Example 1. The material was obtained.

Example 6 A thermosensitive recording was prepared in the same manner as in Example 1 except that the compound No. (44) was used instead of the compound No. (28) in [B solution] of Example 1. The material was obtained.

Example 7 A thermosensitive recording was prepared in the same manner as in Example 1 except that the compound of the liquid No. (28) was used in place of the compound No. (28) in the [solution B] of Example 1. The material was obtained.

Example 8 A thermosensitive recording was prepared in the same manner as in Example 1 except that the compound of the liquid No. (28) was used in place of the compound No. (28) in the [solution B] of the example 1. The material was obtained.

(Comparative Example 1) A heat-sensitive material was prepared in the same manner as in Example 1 except that 2,4'-dihydroxydiphenylsulfone was used in place of compound No. (28) in [B solution] of Example 1. A recording material was obtained.

(Comparative Example 2) A heat-sensitive material was prepared in the same manner as in Example 1 except that Compound No. (28) was replaced with 3-nitrophthalic acid mono-α-methyl ester in [Liquid B] of Example 1. A recording material was obtained.

(Comparative Example 3) A thermosensitive recording material was obtained in the same manner as in Example 1 except that the following structural formula compound was used in place of the compound No. (28) in the [solution B] of Example 1. Was.

[0055]

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Comparative Example 4 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the heat-sensitive recording layer was formed directly on the support (wood free paper) without providing the undercoat layer.

The following tests were performed on the heat-sensitive recording material prepared as described above, and the results are shown in Table 1. <Color development test> Head power 0.68 W /
dot, a pulse width of 0.8 under the conditions of a recording time of 10 ms / line, a scanning line density of 8 × 3.85 dots / mm
Printing was performed at 1.0 and 1.2 ms, and the image density at each pulse width was measured with a Macbeth densitometer to evaluate the color development sensitivity characteristics. <Image part preservation test> Using a thermal gradient tester manufactured by Toyo Seiki Co., Ltd., a heat block at a temperature at which each sample shows a saturation concentration is 2 kg /.
Printing was performed under the conditions of cm ² and 1 second to prepare an image sample before the test. (Plasticity resistance test) Three vinyl chloride wrap films (manufactured by Shin-Etsu Polymer Co., Ltd.) were placed on the test sample, and a 5 kg load was applied. evaluated. (Oil resistance test) Apply cottonseed oil to the test sample and apply 40%.
The image density after standing at 15 ° C. for 15 hours was measured with a Macbeth densitometer to evaluate oil resistance. (Heat Resistance Test) The image density of the test sample left at 100 ° C. for 15 hours was measured with a Macbeth densitometer to evaluate the heat resistance.

[0058]

[Table 3]

[0059]

As described above, the heat-sensitive recording material of the present invention has the following properties.
It is extremely effective in all of oil resistance and heat resistance. Further, the present invention having an undercoat layer made of hollow fine particles has an effect of being excellent in color sensitivity characteristics and excellent in image preservability.

Claims (4)

[Claims] 1. A heat-sensitive recording material having a thermosensitive coloring layer mainly composed of a leuco dye and a color developing agent for developing the leuco dye upon heating on a support, wherein an aromatic compound having an acidic functional group as a substituent. Group 2 in one molecule
A heat-sensitive recording material comprising at least one compound having at least one compound. 2. The heat-sensitive recording material according to claim 1, wherein the acidic functional group is a carboxyl group. 3. A compound having two or more aromatic sulfonyl groups having one or more acidic functional groups as substituents in a molecule is represented by the following general formula (IV). 2. The heat-sensitive recording material according to item 1. Embedded image 4. The heat-sensitive recording material according to claim 1, wherein an undercoat layer containing plastic spherical hollow fine particles is provided between the support and the heat-sensitive recording layer.