JPH021377A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance color forming properties and image stability by providing a thermal color forming layer comprising a specified leuco dye and a color developer on a support, and providing thereon a protective layer comprising a water-soluble high-molecular weight compound, an acidic zirconium salt and a filler. CONSTITUTION:A thermal color forming layer comprising a leuco dye of formula I (R1 is an up to 8C alkyl, R2 is an up to 8C alkyl, 5-7C cycloalkyl, benzyl or phenyl, each of X<1> and X<2> is an up to 8C alkyl, alkoxyl, F, Cl or Br, and X<3> is Cl or Br) and a color developer as main constituents is provided on a surface of a support. Then, a protective layer comprising a water-soluble high- molecular weight compound, an acidic zirconium salt, as a hardener, and a filler is provided on the color forming layer to produce a thermal recording material. The color developer may be a phenolic compound, a thiophenolic compound or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to improvements in heat-sensitive recording materials that utilize a color-forming reaction between a leuco dye and a color developer.

[Prior art]

Thermosensitive recording materials generally consist of a support such as paper, synthetic paper, or plastic film provided with a thermosensitive coloring layer containing a thermochromic composition as a main component, and can be heated with a thermal head, thermal pen, laser beam, etc. A colored image is obtained.

Compared to other recording materials, this type of recording material does not require complicated processing such as development and fixing, can produce records in a short time using relatively simple equipment, and generates less noise and pollutes the environment. It is widely used in many fields due to its advantages such as low cost.

In recent years, optical character reading devices and barcode reading devices have been developed, and their usage is increasing.However, in these devices, light sources with light wavelengths of 700 m or more using light emitting diodes or semiconductor lasers are required as light sources. Commonly used. However, conventionally used leuco dyes such as fluorane and triphenylmethane have almost no light absorption in the near-infrared region of 700 rrtn or more, and cannot be read by the above-mentioned reading device.

Several proposals have been made for leuco dyes that absorb light in the near-infrared region, such as Japanese Patent Publication Nos. 58-5940, 199757-1980, and 2308-1986.
No. 90 and Japanese Unexamined Patent Publication No. 62-106964.

However, these leuco dyes have disadvantages in that the leuco dye itself is yellow, causes background fogging, and has insufficient coloring properties and stability of colored images.

Also, JP-A-62-243653, JP-A-62-257
Publication No. 970 discloses a divinyl compound represented by the above general formula (1), and this compound is pale in color and has excellent color development. However, there is a problem in that the colored image fades when it comes into contact with chemicals such as solvents and plasticizers.

In addition, when trying to improve resistance to chemicals by applying a protective layer containing water-soluble polymer as the main component on the heat-sensitive coloring layer, formalin, glyoxal, chromium-light pan-melamine, melamine, etc. can be used as a hardening agent. - The use of conventionally known compounds such as formalin, polyamide resin, polyamide-epichlorohydrin resin, and aziridine compounds tends to impair the coloring properties of leuco dyes, and not only the chemical resistance and image stability. However, a problem arose in that the stability of the colored image in terms of heat resistance and water resistance also deteriorated.

〔the purpose〕

An object of the present invention is to use a leuco dye that absorbs light in the near-infrared region to enable reading with a reading device using a light emitting diode or semiconductor laser as a light source with a wavelength of 700 to 11,000 nm.

The object of the present invention is to provide a heat-sensitive recording material that has high color development and excellent image stability.

〔composition〕

According to the present invention, in a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer as main components and a protective layer composed of a water-soluble polymer, a curing agent, and a filler are laminated on the surface of a support,
There is provided a heat-sensitive recording material characterized in that at least one compound represented by the following general formula (N) is used as the leuco dye, and an acidic zirconium salt is used as the curing agent.

(In the formula, R0 is an alkyl group with 8 or less carbon atoms, R2 is an alkyl group with 8 or less carbon atoms, a cycloalkyl group with 5 to 7 carbon atoms, a chlorine atom, a bromine atom, an alkyl group with 4 or less carbon atoms as a substituent) represents a benzyl group or a phenyl group that may have a represents 0, ■, 2, or 3, and the x1 comrades of (Xl)m and the x2 comrades of (x2)n may be the same or different.

×3 indicates a chlorine atom or a bromine atom. ) That is, the heat-sensitive recording material of the present invention uses the compound represented by the general formula (1) as the leuco dye, and further contains an acidic zirconium salt as a hardening agent in the protective Jm, thereby inhibiting the color development of the leuco dye. It does not stain, has high color development, and
It has excellent image stability.

Specific examples of the compound represented by the general formula (1) used in the present invention include the following.

(1) 3.3-bis[2-(p-dimethylaminophenyl)=2-(phenylethynyl]~4,5,6.7
-Titrachlorophthalide (2) 3.3-bis[2-(ρ-dimethylaminophenyl)-2-(ρ-methylphenyl)ethynyl]-4
．． 5,6.7-Titrachlorophthalide (3) 3.3-bisC2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)ethynyl]-
4,5,6,7-Titrachlorophthalide (4) 3.3-bis[2-(p-dimethylaminophenyl)-2-(p-ethoxyphenyl)ethynyl)-
4,5,6,7-titrachlorophthalide (5) 3.3-bis[2-(dodimethylaminophenyl)-2-(m + p-dimethylphenyl)ethynyl)-4,5,6゜7 -Titrachlorophthalide (6) 3.3-bis(2-(p-dimethylaminophenyl)-2-(0-methyl-ρ-methoxyphenyl)
ethynyl]-4.5,6.7-titrachlorophthalide (
7) 3.3-bis(2-(p-dimethylamino-0
-methylphenyl)-2-phenylethynyl)-4,5
,6,7-titrachlorophthalide (8) 3.3-bis[2-(p-dimethylamino-
0-chlorophenyl)-2-(ρ-methylphenyl)ethynyl]-4,5,6,7-titrachlorophthalite (9
) 3.3-bis[2-(p-dimethylaminophenyl)-2-(p-chlorophenyl)ethynyl)-4,5
,6,7-titrachlorophthalide (10) 3.3-bisC2-(p-dimethylaminophenyl)2-(o, p-dimethoxyphenyl)
ethynyl)-4,5°6.7-titrachlorophthalide(il) 3.3-bis[2-(p-methylbutylaminophenyl)-2-(p-methoxyphenyl)ethynyl)-4,5° 6.7-Titrachlorophthalide (12) 3.3-bis(2-(p-dimethylaminophenyl)-2-(p-octylphenyl)ethynyl)
-4,5,6,7-te1-lachlorophthalide (13) 3.3-bis(2-(p-dimethylaminophenyl)-2-(p-hexyloxyphenyl)ethynyl]-4°5.6 .7-Titrachlorophthalide (14) 3.3-bis[2-(p-methylcyclohexylaminophenyl)-2-(p-methylphenyl)
ethynyl]-4.5,6.7-te1herachlorophthalate (15) 3.3-bis(z-(p-ethylbenzylaminophenyl)-2-(p-methoxyphenyl)ethynyl]-4゜5. 6.7-te1-rachlorophthalide (16) 3.3-bis[2-(p-dimethylaminophenyl)2-phenylethynyl)-4,5,6,7-
Titrabromophthalite (17) 3.3-bis(2-(p-dimethylaminophenyl)2-phenylethynyl]-5-chloro-4,
6,7-dribromophthalide (18) 3.3-bis(2-(P-dimethylaminophenyl)-2-(p-methoxyphenyl)ethynyl)
-5,6-cyclorho4. Fudipromophthalide Specific examples of acidic zirconium salts used in the present invention include the following. Inorganic polymers of zirconium nitrate, zirconium sulfate, zirconium acetate, zirconium acid chloride, and zirconium acid chloride.

Examples of water-soluble polymers to be contained in the protective layer of the present invention include polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, starch and its derivatives, casein, sodium alginate, polyvinylpyrrolidone, polyacrylamide, styrene,
Malenic acid copolymers and the like are commonly used.

Fillers such as calcium carbonate, silica, magnesia, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay talc, surface-treated calcium and silica, as well as styrene/methacrylate Organic fine powders such as acid copolymers and polystyrene resins can also be added.

In the present invention, the leuco dye represented by the general formula (I) is used, but other leuco dyes can also be used in combination, if necessary. As such a leuco dye, those applied to this type of heat-sensitive material can be arbitrarily applied.
For example, leuco compounds of triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based dyes are preferably used. Specific examples of such leuco dyes include those shown below.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-glorfluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-amyl-6-methyl-7-anilinofluorane, 3-diethylamino-7-chlorofluorane .

3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane.

3-diethylamine-6-methyl-7-chlorofluorane, 3-(N-p-tolyl-N-dithylamino)-6-methyl-7-anilinofluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoictolactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluorane, 3-diethylamino-7-(o- chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl -7-(2', 4'-
dimethylanilino)fluoran, 3-(N,N-diethylamino)-5-methyl-7-(
N,N-dibenzylamino)fluoran, benzoylleucomethylene blue 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide,3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide,3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide,3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-57
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-( N-benzyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-p-toluidino)-7-(,α-phenylethylamino)fluoran, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7- (α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-〇-butylanilino)fluoran, 3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino- 6-Methyl-7-anilinofluorane, 3,6-bis(dimethylamino)fluorene spiro(9
゜3')-6'~dimethylaminophthalide, 3-(N
-benzyl-N-cyclohexylamino)-5,6-penzo-7-α-naphthylamino-4'bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl)amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-
6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino 4', 5'-benzofluorane, and the like.

In addition, in the present invention, the color developer used is as follows:
Various electron-accepting compounds that cause the leuco dye to develop color upon contact are preferably applied, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, and specific examples thereof are shown below. Examples include things like:

4.4'-Impropylidene bisphenol, 4.4
′ -inpropylidene bis(O-methylphenol)
, 4.4'-Secondary-butylidene bisphenol 4.4'-Isopropylidene bis(2-tert-
butylphenol), 4.4'-cyclohexylidene diphenol, 4.4
′ -isopropylidene bis(2-chlorophenol)
, 2.2'-methylenebis(4-methyl-6-tert-butylphenol), 2.2'-methylenebis(4-ethyl-6-tert-butylphenol), 4.4'-butylidenebis(6-tert-butyl- 2-methylphenol), 1.1.3-tris(2-methyl-4-hydroxy-5
-tert-butylphenyl)butane, 1.1.3-
Tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4.4'-diphenolsulfone, 4.4'-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4'- Hydroxydiphenyl sulfone.

4.4'-diphenol sulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis(4-hydroxyphenylthio) )-3,5
-Dioxahebutane, 1.5-bis(4-hydroxyphenylthio)-3-oxapentane, 1.3-bis(4-hydroxyphenylthio)-propane, 1.3-bis(4-hydroxyphenylthio) -2-Hydroxypropane, N,N'-diphenylthiourea, N,N'-di(m-chlorophenyl)thiourea, salicylanilide, 5-chloro-salicylanilide, 2-hydroxy-3-naphthoe, 2- Hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum, calcium, etc., bis(4-hydroxyphenyl)acetic acid methyl ester, bis-(4-hydroxyphenyl) Benzyl acetate ester, 1.3-bis(4-hydroxycumyl)benzene, 1.
4-bis(4-hydroxycumyl)benzene, 2.4'
-diphenolsulfone, 3,3'-diallyl-4,4'-diphenolsulfone, α,α-bis(4-hydroxyphenyl)-α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, Tetrabromobisphenol S, etc.

In the present invention, various conventional binders can be used as appropriate to bind and support the leuco dye, color developer, and auxiliary components on the support.

For example, polyvinyl alcohol, starch and its derivatives,
Cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrroli I, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid ester/methacrylic acid terpolymer In addition to water-soluble polymers such as , styrene/maleic anhydride copolymer alkali salt, imbutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, and polyacrylic Examples include emulsions such as acid esters, polymethacrylate esters, vinyl chloride/vinyl acetate copolymers, ethylene/vinyl acetate copolymers, and latexes such as styrene/butadiene copolymers and styrene/butadiene/acrylic copolymers. It will be done.

In the present invention, in addition to the leuco dye, color developer, and auxiliary components, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible A sexual substance (or lubricant), etc. can be used in combination. In this case, fillers include, for example, inorganic microorganisms such as lucium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated calcium and silica. In addition to powder, organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be used.

Examples of thermofusible substances include 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 behenic acid. Fatty acid metal salts such as zinc acid, dobenzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naph 1-diacetic acid phenyl ester 1-hydroxy-2-naphthoic acid phenyl ester,
1-Hydroxy-2-naphthoic acid methyl ester, diphenyl carbonate, terephthalic acid dibenzyl ester, terephthalic acid dimethyl ester, 1゜4-dimethoxynaphthalene, 1,4-jethoxynaphthalene, 1,4-
Dibenzyloxynaphthalene, 1,2-bis(phenoxy)ethane, 1,2-bis(3-methylphenoxy)ethane, ■, 2-bis(4-methylphenoxy)ethane,
1,4-bis(phenoxy)butane, 1,4-bis(phenoxy)-2-butene, dibenzoylmethane, 1°4
-bis(phenylthio)butane, 1,4-bis(phenylthio)-2-butene, 1,3-bis(2-vinyloxyl-oxy)benzene, 1,4-bis(2-vinyloxyethoxy)benzene, p -(2-vinyloxyethoxy)biphenyl, p-aryloxybiphenyl, P
-Propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyl disulfide, ■, 1-diphenylethanol.

1.1-diphenylpropatol, p-(benzyloxy)benzyl alcohol, 1,3-diphenoxy-2-
Propatool, N-octadecylcarbamolyl-p-
Examples include methoxycarbonylbenzene and N-octadecylcarbamoylbenzene.

In addition, in the present invention, between the support and the thermosensitive coloring layer,
It is also possible to provide an undercoat layer if necessary. In this case, the above-mentioned filler, binder, thermofusible substance, surfactant, etc. can be used as components constituting the undercoat layer.

The heat-sensitive recording material of the present invention can be used in various fields like conventional ones, but in particular, it can be used in optical literature readers and label bar kneaders by taking advantage of its excellent near-infrared light absorption properties. - Can be used as a recording material for reading records with a barcode reader.

In addition, when the recording material of the present invention is used as a heat-sensitive recording label sheet 1-, a heat-sensitive coloring jet containing the above-mentioned leuco dye and color developer is provided on one side of the support, and It may have a structure in which a release mount is provided via an adhesive Jτ.

〔effect〕

Since the heat-sensitive recording material of the present invention uses the compound represented by the general formula (I) as the leuco dye, the colored image has light absorption in the near-infrared region, so a light emitting diode or semiconductor laser is used as the light source. It can be read by optical character reading devices and barcode reading devices, and it also has a protective layer using acidic zirconium salt as a hardening agent.
It has high color development and excellent image stability.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 Solutions [A] to (B) having the following compositions were dispersed using a sand grinder for 2 to 4 hours to prepare each solution.

[Liquid A]

10% polyvinyl alcohol aqueous solution 20 parts water 60 parts [B-ki] Calcium carbonate 20 parts 10
% polyvinyl alcohol 40 parts water

120 parts of [Liquid C] were mixed and stirred to have the following composition.

[Liquid C]

Zirconium acid chloride inorganic polymer 10 parts 30
% zinc stearate dispersion 3 parts silica 3 parts 10% polyvinyl alcohol 100 parts water
20
Next, [Liquid A] and [Liquid B] were mixed and stirred at a weight ratio of 1:3 to prepare a thermosensitive coloring M coating liquid.

This coating liquid was applied to a high-quality paper of 52 g/m2 at a dry weight of 2 to 3 H/rr? I applied it and let it dry. [Liquid C] is applied thereon to a dry weight of 2 to 3 g/m, and after drying, calendering is performed to obtain a Beck smoothness of 500 to 3000 seconds to create the recording material of the present invention. did.

Example 2 3,3-bis(2-(p-dimethylaminophenyl)-2-(ρ-methoxyphenyl)ethynyl) of [Liquid A] of Example 1 = 4.5,6.7-titrachlorophthari 3,3-bis(2-(p-dimethylaminophenyl)-2-(p-methylphenyl)ethynyl)-4,
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that 5,6,7-titrabromophthalite was used.

Example 3 Example 1 except that zirconium acid chloride was used instead of the inorganic polymer of zirconium acid chloride in [Liquid C] of Example 1.
A heat-sensitive recording material was prepared in the same manner.

Example 4 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that zirconium sulfate was used instead of the inorganic polymer of zirconium acid chloride in [Liquid C] of Example 1.

Example 5 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that zirconium acetate was used instead of the inorganic polymer of zirconium acid chloride in [Liquid C] of Example 1.

Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1, except that polyamide-ebichlorhythrin resin was used instead of the inorganic polymer of zirconium acid chloride in [Liquid C] of Example 1.

Comparative Example 2 Example 1 except that an aziridine compound was used instead of the inorganic polymer of zirconium acid chloride in [Liquid C] of Example 1.
A heat-sensitive recording material was prepared in the same manner.

Comparative Example 3 A comparative heat-sensitive recording material was prepared in the same manner as in Example 2, except that polyamide-ebichlorhythrin resin was used instead of the inorganic polymer of zirconium acid chloride in [Liquid C] of Example 2. .

Comparative Example 4 Example 2 except that an aziridine compound was used instead of the inorganic polymer of zirconium acid chloride in [Liquid C] of Example 2.
A heat-sensitive recording material for comparison was prepared in the same manner as described above.

The heat-sensitive recording material obtained as described above was subjected to various tests for dynamic color development sensitivity, heat resistance, oil resistance, plasticizer resistance, water resistance, and temperature and humidity resistance using the methods shown below. 900
The reflectance in nm was measured. The results are shown in Table-1.

i) Dynamic color development sensitivity Using a printing experiment device manufactured by Matsushita Seiko Parts Co., Ltd. and equipped with a thin film head, the head voltage was 0.68 W/dat, the recording time per line was 10 m5i, and the scanning line density was 8 x 3.85 dots/ Pulse width 0.5.0.6.0.7.0.
8.0.9.1, print at 0ms, each pulse dJ
The reflectance of the printed image was measured.

ii) Preservability test Similar to the dynamic color development sensitivity test, printing was performed with a pulse width of 0.9 ms to prepare a test sample.

]ii-■ Heat resistance...The above printed sample was heated to 70°C.
, the image area and reflectance after being left for 24 hours under dry conditions were 81! I decided.

1i) - ■ Oil resistance: After applying cottonseed oil to the surface of the above printed sample and leaving it for 24 hours at 40°C under dry conditions, the reflectance of the image area was 4! It has been decided.

1i) -■Plasticizer resistance...Layer 10 sheets of PVC rubber on the surface of the above printed sample, apply a load of 5-,
℃ and under dry conditions for 24 hours, the reflectance of the image area was measured.

1i) - Water resistance: The above printed sample was immersed in water at 20° C. for 24 hours, dried at room temperature, and the reflectance of the image area was measured.

11)-■ Temperature and humidity resistance...The above printed sample was heated to 40℃
The reflectance of the image area was measured after being left for 24 hours under -90% RI+ conditions.

iii) Measurement of reflectance The reflectance of the printed image area at 900 nm was measured using a Hitachi Model 330 spectrophotometer.

As is clear from Table 1, the heat-sensitive recording material of the present invention is
Compared to the comparative example, it has high color development and excellent image stability in various storage tests including oil resistance and plasticizer resistance.

Claims (1)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer as main components and a protective layer composed of a water-soluble polymer, a curing agent, and a filler are laminated on the surface of a support, the leuco dye is as follows: A heat-sensitive recording material characterized by using at least one compound represented by the general formula (I) and using an acidic zirconium salt as the curing agent. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R_1 is an alkyl group with 8 or less carbon atoms, R_2 is an alkyl group with 8 or less carbon atoms, a cycloalkyl group with 5 to 7 carbon atoms, or as a substituent. Indicates a chlorine atom, a bromine atom, a benzyl group or a phenyl group that may have an alkyl group with a carbon number of 4 or less. , represents a fluorine atom, a chlorine atom or a bromine atom, m and n represent 0, 1, 2 or 3, (X^1) m's X^1 comrade, (X^2) n
The X^2 comrades may be the same or different. X
^3 represents a chlorine atom or a bromine atom. )