JPH09150577A - Thermal recording medium - Google Patents

Abstract

(57) [PROBLEMS] To provide a thermosensitive recording medium excellent in recording image quality. SOLUTION: In a heat-sensitive recording material in which a heat-sensitive recording layer containing a leuco dye and a color former is provided on a support, an acetylene glycol compound represented by the following general formula (1) is heat-sensitive in the heat-sensitive recording layer. 0.1 to the total solid content of the recording layer
1.0% by weight. Embedded image [In the general formula (1), R ₁ is a methyl group, an ethyl group,
It represents a propyl group or a butyl group, and R ₂ is-(OC ₂ H
_{4) n} OH or - represents a _{(OC 3 H 6) n OH} . n represents an integer of 1 to 10. ]

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 utilizing a color-forming reaction between a leuco dye and a color-developing agent, and more particularly to a heat-sensitive recording material having excellent recording image quality.

[0002]

2. Description of the Related Art A thermosensitive recording medium is known in which a coloring image is obtained by utilizing a coloring reaction with a leuco dye and a coloring agent to bring both coloring substances into contact with each other by heat. Since such a thermosensitive recording medium is relatively inexpensive, the recording device is compact, and its maintenance is relatively easy, it is used not only as a recording medium for facsimiles and various computers, but also in a wide range of fields. .

Examples of such fields of use include those for ultrasonic waves,
There are thermal recording materials for X-ray film, OHP, plate making, and magnetic cards. The thermal recording material used in these fields of application is required to have a recording image quality close to that of a silver salt photograph as a quality. For example, a thermal recording material using a film as a support can obtain excellent recording image quality, but coating unevenness due to bubbles in a coating liquid for forming a thermal recording layer or poor wettability of the coating liquid to the film. Occurrence may occur and uniform recording image quality may not be obtained.

As a method for improving coating unevenness, a method of adding an antifoaming agent, a dispersant, a surfactant, etc. to the coating liquid is known, but it is necessary to add bubbles to the coating liquid or a film of the coating liquid. The present situation is that coating unevenness due to poor wettability has not been sufficiently improved. For example, a method of incorporating acetylene glycol as a surfactant into a heat-sensitive recording layer for the purpose of preventing background fogging is described in JP-A-4-97892, but the purpose and effect of the present application are different.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium having excellent recording image quality.

[0006]

DISCLOSURE OF THE INVENTION The present inventor has found that in a heat-sensitive recording material having a heat-sensitive recording layer containing a leuco dye and a color former on a support, the following general formula ( It was found that the above problem can be solved by containing the acetylene glycol compound represented by 1) in an amount of 0.1 to 1.0% by weight based on the total solid content of the heat-sensitive recording layer.
The present invention has been completed.

[0007]

Embedded image

[In the general formula (1), R ₁ represents a methyl group, an ethyl group, a propyl group or a butyl group, and R ₂
Is _{- (OC 2 H 4) n} OH or _{- (OC 3 H 6) n} O
Represents H. n represents an integer of 1 to 10. ]

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a leuco dye and a color-forming agent. The specific acetylene glycol compound is contained in an amount of 0.1 to 1.0% by weight based on the total solid content of the heat-sensitive recording layer.
If it is less than 1% by weight, uneven coating occurs on the surface of the thermosensitive recording layer due to bird's eyes and bubbles in the coating liquid for the thermosensitive recording layer, and a uniform coated surface cannot be obtained. If it exceeds 1.0% by weight, background fog may occur over time.
The range of weight% is more preferred.

As the colorless or light-colored leuco dyes used in such a heat-sensitive recording layer, various types are known, and the following may be mentioned, for example.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylamino Phthalide, 3-
Diethylamino-7-dibenzylamino-benzo [a]
Blue-coloring dye such as fluoran; 3- (N-ethyl-N-)
green-coloring dyes such as p-tolyl) amino-7-N-methylanilinofluorane and 3-diethylamino-7-anilinofluorane;

3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3-diethylamino-7-
Methylfluorane, 3-diethylamino-6-methyl-
7-chlorofluorane, 3-diethylamino-7-chlorofluorane, rhodamine (p-chloroanilino) lactam, 3- (N-ethyl-p-toluidino) -7-methylfluorane, 3,3'-bis (1 -N-butyl-2-
Methylindol-3-yl) phthalide and other red-coloring dyes;

3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-
Methyl-N-cyclohexyl) amino-6-methyl-7
-Anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6
-Methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3
-Di (n-amyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-di (n-butyl) amino-7
-(O-chloroanilino) fluoran, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-
Di (n-butyl) amino-7- (o-fluoroanilino) fluoran, 3-diethylamino-7- (m-trifluoromethylanilino) fluoran, 3- (N-ethyl-p-toluidino) -6 Methyl-7-anilinofluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p-toluidino) fluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3 −
Black coloring dyes such as di (n-butyl) amino-6-methyl-7-m-toluidinofluorane and 3-piperidino-6-methyl-7-anilinofluorane;

3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-
2-yl] -4,5,6,7-tetrachlorophthalide,
3,3-bis [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide, 3-p- (p
-Dimethylaminoanilino) anilino-6-methyl-7
-Chlorofluoran, 3-p- (p-chloroanilino)
Anilino-6-methyl-7-chlorofluoran, 3,6
-Bis (dimethylamino) fluorene-9-spiro-
Dyes and the like having an absorption wavelength in the near infrared region at the time of color development such as 3 '-(6'-dimethylamino) phthalide. Of course, the present invention is not limited to these, and two or more kinds may be used in combination if necessary, and the amount used is 5 to 40% by weight, preferably 8 to 30% by weight based on the heat-sensitive recording layer. Used in the range.

As the colorant used in combination with the leuco dye, various known ones can be used, for example, 4,4'-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2, 2-bis (4-
Hydroxyphenyl) -4-methylpentane, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, bis (3- Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4′-methyldiphenyl sulfone, 4-hydroxyphenyl-4′-benzyloxyphenyl sulfone, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4'-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4 '
-Hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, 2,2 ′
-Phenolic compounds such as thiobis (3-tert-octylphenol); thiourea compounds such as N, N'-di-m-chlorophenylthiourea;4,4'-bis (Np
- toluenesulfonyl aminocarbonylamino) diphenylmethane, compounds having -SO ₂ NH- bond in the molecule, such as N-p-toluenesulfonyl -N'- phenylurea; p-chlorobenzoic acid zinc, 4- [2-(p -Methoxyphenoxy) ethyloxy] zinc salicylate, 4-
Examples thereof include zinc salts of aromatic carboxylic acids such as zinc [3- (p-tolylsulfonyl) propyloxy] salicylate and zinc 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylate.

In the present invention, the use ratio of the leuco dye and the color former in the heat-sensitive recording layer should be appropriately selected according to the kinds of the color former and the color former to be used, and it is not particularly limited. When using dyes and acidic substances,
Generally, a color former is used in an amount of 1 to 7 parts by weight, preferably about 1 to 4 parts by weight, based on 1 part by weight of the leuco dye.

The heat-sensitive recording layer generally uses water as a dispersion medium,
The leuco dye and the coloring agent are finely dispersed together with a stirring or crushing machine such as a ball mill, attritor, or sand mill so that the average particle diameter of each is 2 μm or less, and then an adhesive is added. It is formed by coating and drying the prepared coating liquid for heat-sensitive recording layer on a support.

Examples of the adhesive include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic,
Polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt,
Ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, natural rubber emulsion, styrene / butadiene copolymer emulsion, acrylonitrile / butadiene copolymer emulsion, methyl methacrylate / butadiene copolymer emulsion, At least one of polychloroprene emulsion, vinyl acetate emulsion, ethylene / vinyl acetate emulsion and the like is added to the heat-sensitive recording layer in an amount of 10 to 40% by weight, preferably 15 to 35% by weight.

If desired, various auxiliary agents can be added to the heat-sensitive recording layer coating liquid within the range that does not impair the effects of the present invention. For example, sodium dioctylsulfosuccinate and dodecylbenzenesulfonic acid. Surfactants such as sodium, sodium lauryl alcohol sulfate, fatty acid metal salts, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, kaolin, clay, calcium carbonate, calcined clay, calcined kaolin , Aluminum hydroxide, amorphous fine particle silica, styrene microballs, nylon powder, polyethylene powder, pigments such as urea / formalin resin filler, and other defoaming agents, fluorescent dyes, coloring dyes and the like are appropriately added.

Further, a sensitizer for increasing recording sensitivity and a preservative improving material for enhancing preservability of recorded images may be added. Specific examples of the sensitizer include stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, and methylenebisstearic acid. Amide, N-methylolstearic acid amide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, oxalic acid-di -P-methylbenzyl, oxalic acid-di-p-chlorobenzyl, p-benzylbiphenyl, di (p-methoxyphenoxyethyl) ether,
1,2-di (3-methylphenoxy) ethane, 1,2-
Di (4-methylphenoxy) ethane, 1,2-di (4-
Methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1
-(4-Methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenetizide, N-acetoacetyl -P-toluidine, di (β-biphenylethoxy)
Benzene, p-di (vinyloxyethoxy) benzene,
Examples include 1-isopropylphenyl-2-phenylethane and the like. The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within the range of 4 parts by weight or less relative to 1 part by weight of the color developing agent.

Specific examples of the storage stability improver include, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) and 2,2'-ethylenebis (4-methyl-6-tert-butylphenol). , 2,2'-methylenebis (4,6-di-tert-butylphenol), 2,
2′-ethylidenebis (4,6-di-tert-butylphenol), 2,2′-methylenebis (4-methoxy-6
-Tert-butylphenol), 2,2′-methylenebis (6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 4,
4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methoxy-6-tert
-Butylphenol), 4,4'-thiobis (2-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-m-cresol), 1-
[Α-Methyl-α- (4′-hydroxyphenyl) ethyl] -4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl-) 4-hydroxy-5-cyclohexylphenyl)
Butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4′-
Thiobis (3-methylphenol), 2,2-bis (4
-Hydroxy-3,5-dichlorophenyl) propane,
Hindered phenol compounds such as 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, N,
N'-di-2-naphthyl-p-phenylenediamine,
2,2'-methylenebis (4,6-di-tert-butylphenyl) sodium phosphate, 2- (2'-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-
5′-methylphenyl) benzotriazole, 2-
(2'-hydroxy-5'-tert-butylphenyl) benzotriazole etc. are mentioned.

Providing a protective layer on the heat-sensitive recording layer for the purpose of enhancing plasticity resistance, storability, recording runnability, etc. is one of preferred forms of use. The protective layer is composed mainly of a water-soluble resin, and specific examples of the water-soluble resin include starches such as oxidized starch, enzyme-modified starch, cation-modified starch, esterified starch, etherified starch, and the like. Cellulose derivatives such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, methoxy cellulose, hydroxyethyl cellulose, completely (or incompletely) saponified polyvinyl alcohol,
Polyvinyl alcohols such as carboxy-modified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, silicon-modified polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid copolymer Combined, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, sodium alginate, gelatin, water-soluble polymers such as casein, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester,
Latexes such as polybutyl methacrylate, styrene / butadiene copolymer, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer, and styrene / butadiene / acrylic copolymer are exemplified. Among these, polyvinyl alcohols such as completely (or incompletely) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, and silicon-modified polyvinyl alcohol, which exhibit an excellent effect of preserving recorded images, are particularly preferable. preferable.

The coating liquid for the protective layer is prepared by using water as a dispersion medium and mixing and stirring a water-soluble resin. In the coating liquid, if necessary, silicone oil emulsion, zinc stearate, calcium stearate, carnauba wax,
Lubricants such as paraffin wax and ester wax, calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, amorphous fine particle silica, aluminum hydroxide, barium sulfate, talc, kaolin, clay, calcined clay, colloidal silica and other pigments, and dispersion Auxiliary agents such as agents, defoaming agents, coloring dyes, fluorescent dyes, curing agents, and ultraviolet absorbers can be added.

The method for forming the heat-sensitive recording layer and the protective layer is not particularly limited, and examples thereof include air knife coating, varibar blade coating, pure blade coating, rod blade coating,
It is formed by applying and drying the coating solution for the thermal recording layer on a support such as high-quality paper, coated paper, transparent film, synthetic paper, etc. by an appropriate application method such as short dwell coating, curtain coating, die coating, etc. It Further, the coating amount of the coating liquid for the thermosensitive recording layer is 1 by dry weight.
It is adjusted in the range of ^{20 to 20} g / m ² , preferably 5 to 15 g / m ² . The coating amount of the coating liquid for the protective layer is 0.5 to 5 g /
Adjusted in the range of m ² .

In general, even when a transparent film such as a polyester film, a polypropylene film or a polycarbonate film having a haze value of 30% or less, which makes it difficult to form a uniform coated surface, is used as a support, the heat-sensitive material containing the general formula (1) is used. Since the coating liquid for the recording layer forms an extremely uniform coated surface, a thermosensitive recording medium having excellent recording image quality can be obtained.

The thermosensitive recording medium of the present invention is provided with a glossy layer containing a resin which is cured by electron beam or ultraviolet irradiation on the protective layer, or is subjected to a super calender treatment.
Various well-known techniques in the field of manufacturing a thermosensitive recording medium, such as providing an antistatic layer on the back surface or performing an adhesive processing, can be appropriately added.

[0027]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto. Further, unless otherwise specified, parts and% in the examples indicate parts by weight and% by weight, respectively.

Example 1 Preparation of Solution A 3- (N-ethyl-N-isoamylamino) -6-methyl-7-phenylaminofluorane 20 parts, 1,2-di (3-methylphenoxy) ethane 10 Parts, 30 parts of a 5% aqueous solution of methyl cellulose, and 60 parts of water were pulverized with a sand mill until the average particle size became 0.8 μm.

Preparation of Solution B A composition consisting of 20 parts of 4-hydroxy-4′-isopropoxydiphenyl sulfone, 20 parts of a 5% aqueous solution of methylcellulose, and 40 parts of water was pulverized with a sand mill until the average particle diameter became 0.8 μm. did.

Preparation of Coating Liquid for Thermal Recording Layer Liquid A 100 parts, liquid B 120 parts, amorphous fine particle silica-silica 20 parts, solid content 50% styrene / butadiene copolymer 58 parts, acetylene glycol (Surfynol 440, In the general formula (1), R ₁ is a butyl group, R ₂ is — (OC ₂ H ₄ ) _n OH, manufactured by Air Products Co., Ltd. 2
% Aqueous solution 12 parts and water 50 parts were mixed and stirred to obtain a thermal recording layer coating liquid.

Preparation of Thermosensitive Recording Material On a synthetic paper (trade name: YUPO FPG # 80, manufactured by Oji Yuka Synthetic Paper Co., Ltd.), the coating amount for the thermal recording layer was 7 g / m ² after drying. After coating and drying so as to form a thermosensitive recording layer, a supercalendering treatment was performed to obtain a thermosensitive recording material.

Example 2 In the preparation of the coating liquid for the thermosensitive recording layer of Example 1, a 2% aqueous solution of acetylene glycol 1
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the amount of 2 parts was changed to 7 parts.

Example 3 In the preparation of the coating liquid for the thermosensitive recording layer of Example 1, a 2% aqueous solution of acetylene glycol 1
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 2 parts and 50 parts of water were replaced with 40 parts of a 2% aqueous solution of acetylene glycol and 10 parts of water.

Example 4 In the formation of the thermosensitive recording layer of Example 1, a synthetic paper [trade name: YUPO FPG # 8 was used as the support.
0, haze value 100%, manufactured by Oji Yuka Synthetic Paper Co., Ltd., and subjected to corona discharge treatment [A-7
300, thickness 75 μm, haze value 2%, manufactured by Toyobo Co., Ltd. was used to obtain a thermosensitive recording medium in the same manner as in Example 1.

[Example 5] On the thermosensitive recording layer of Example 1, the following coating solution for protective layer was applied and dried so that the coating amount after drying was 2 g / m ² , to obtain a thermosensitive recording material. Preparation of coating liquid for protective layer 150 parts of 10% aqueous solution of polyvinyl alcohol modified with acetoacetyl group, aqueous dispersion of kaolin 10 having solid concentration of 60% 10
Parts, 5 parts of 10% aqueous solution of glyoxal, 1 part of 10% aqueous solution of sodium dioctyl sulfosuccinate, solid concentration 30
% Of a zinc stearate aqueous dispersion was mixed and stirred to obtain a protective layer coating liquid.

Comparative Example 1 In the same manner as in Example 1 except that 12 parts of a 2% aqueous solution of sodium dioctylsulfosuccinate was used in place of acetylene glycol in the preparation of the coating liquid for the thermal recording layer of Example 1. A thermosensitive recording medium was obtained.

Comparative Example 2 In the preparation of the coating liquid for the thermosensitive recording layer of Example 1, a 2% aqueous solution of acetylene glycol 1
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 2 parts were used instead of 2.

[Comparative Example 3] In the preparation of the coating liquid for the thermosensitive recording layer of Example 1, a 2% aqueous solution of acetylene glycol 1
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 2 parts and 50 parts of water were changed to 50 parts of a 2% aqueous solution of acetylene glycol.

[Comparative Example 4] In the preparation of the coating liquid for the thermal recording layer of Example 1, acetylene glycol (Surfynol 440, R ₁ in the general formula (1) is a butyl group, R ₂
There _{- (OC 2 H 4) n} OH, in 2% aqueous solution instead of Air Products and Chemicals, Inc.), acetylene glycol (Surfynol 82, the general formula (1) R ₁ is an ethyl group, R ₂
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that a 2% aqueous solution of a hydroxyl group (manufactured by Air Products) was used. [Comparative Example 5] In Comparative Example 1, the support was replaced by a corona discharge treated polyester film [A-7 instead of synthetic paper [trade name: YUPO FPG # 80, manufactured by Oji Yuka Synthetic Paper Co.].
300, thickness 75 μm, haze value 2%, manufactured by Toyobo Co., Ltd.] was used to obtain a thermosensitive recording medium in the same manner as in Comparative Example 1.

The following evaluation tests were performed on the thus obtained heat-sensitive recording medium, and the results are shown in Table 1. Recording density and image quality Thermal evaluation device [Product name: TH-PMD, Okura Electric Co., Ltd.]
The recording density and the unrecorded portion of the recorded image obtained by recording at 3 (mj / dot) were measured using a Macbeth densitometer [Macbeth RD-9
14 type] (visual mode) (however, in the thermosensitive recording medium of Example 4, the whiteness was 8 below the thermal recording medium).
The measurement was performed by spreading a 5% quality paper. ), And the recording quality of the recorded image was visually evaluated as follows. (Judgment Criteria) A: The recorded image has no unevenness and is very uniform. ◯: The recorded image is almost uniform and uniform. Δ: The recorded image is uneven and uneven. X: The recorded image has a lot of unevenness and is very uneven.

Coating unevenness The coating unevenness appearing on the surface of the thermosensitive recording layer of the obtained thermosensitive recording medium was visually judged. (Judgment Criteria) A: There is no coating unevenness and it is very uniform. ◯: Almost no coating unevenness and uniform. Δ: There is coating unevenness and it is non-uniform. X: There are many coating irregularities and they are extremely uneven.

Haze Value The haze value of the support and the thermosensitive recording medium of Example 4 and Comparative Example 5 was measured by a haze meter [trade name: TC-HIV type,
Manufactured by Tokyo Denshoku Co., Ltd.].

[0043]

[Table 1]

[0044]

As is apparent from the results shown in Table 1, the thermosensitive recording medium of the present invention had excellent recording image quality.

Claims (2)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a leuco dye and a color former, wherein the acetylene glycol compound represented by the following general formula (1) is contained in the heat-sensitive recording layer. 0.1 to the total solid content of the thermosensitive recording layer
A thermal recording material containing 1.0% by weight. Embedded image [In the general formula (1), R ₁ is a methyl group, an ethyl group,
It represents a propyl group or a butyl group, and R ₂ is-(OC ₂ H
_{4) n} OH or - represents a _{(OC 3 H 6) n OH} . n represents an integer of 1 to 10. ] 2. The heat-sensitive recording material according to claim 1, wherein the support is a transparent film having a haze value of 30% or less.