JP2006021340A - Thermosensitive recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive recording body, which is highly sensitive and by which a highly dynamic color developing density is obtained and moreover which is excellent in storage stability. <P>SOLUTION: This thermosensitive recording body is formed by providing a thermosensitive color developing layer mainly including a colorless or light-colored basic colorless dye and an organic developer on a support under the condition that the thermosensitive color developing layer includes a mixture of 4-methyl-4'-hydroxydiphenyl sulfone and 4-methyl-2'-hydroxydiphenyl sulfone as the organic developer and at least one kind of compounds expressed by general formula (1) as a sensitizer, wherein X represents an oxygen atom or a sulfur atom, Y represents a 1-6C straight-chain or branched alkyl group, R<SB>1</SB>and R<SB>2</SB>represent each a hydrogen atom, a halogen atom and a 1-6C alkyl group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat-sensitive recording material utilizing a color development reaction between a basic colorless dye and an organic developer.

  In general, a heat-sensitive recording material having a heat-sensitive color developing layer mainly composed of a colorless or light-colored dye precursor and a color developer that reacts with the dye precursor when heated is widely put into practical use (Patent Document 1). . A thermal printer with a built-in thermal head is used for recording on this thermal recording medium, but such a thermal recording method has no noise during recording as compared with other recording methods that have been put to practical use. With the development of the information industry, with the development of the information industry, development and fixing are not necessary, maintenance is free, the equipment is relatively inexpensive and compact, and the resulting color development is very clear. Widely used for various measuring instruments and labels. With the diversification and high performance of these recording apparatuses, the required quality for thermal recording media has become higher. With respect to the color development sensitivity, it is required that a clear color image with a high density can be obtained even with a small amount of heat energy as the apparatus is miniaturized and the recording speed is increased.

  In order to satisfy these requirements, a method for increasing the color development sensitivity by adding a heat-soluble substance in the heat-sensitive layer (Patent Document 2), and a method for increasing the color development sensitivity by using a new developer having a high color development ability ( Patent Document 3) has been proposed. However, all of these methods have sufficient drawbacks such as deterioration of the heat-resistant ground color, wiping with time, and deterioration in color density (reprintability) when printed after long-term storage of uncolored areas. It's hard to say that quality is good. In general, there is known a method in which an appropriate sensitizer is further used in combination with a dye and a developer. For example, when the developer is a phenol compound represented by bisphenol A, p-benzylbiphenyl (patented) Literature 4), benzyl p-benzyloxybenzoate (Patent Literature 5), benzyl naphthyl ether (Patent Literature 6) and the like are used as suitable sensitizers.

  Recently, a method using a trisphenol compound as a developer or an anti-fading agent (Patent Documents 7 and 8) has been disclosed, but a sufficient color density cannot be obtained even if these compounds are used.

  As described above, a heat-sensitive recording material having a high color density and a clear color image even with minute heat energy and having storage stability (heat resistance, moisture resistance, etc.) of the image area has not been obtained yet.

Japanese Examined Patent Publication No. 45-14039 JP-A-56-169087 JP 56-144193 A JP 60-82382 A JP-A-57-201691 JP 58-87094 A Japanese Patent Laid-Open No. 9-278695 JP 2001-96926 A

  An object of the present invention is to provide a heat-sensitive recording material which can obtain a high dynamic color density with minute heat energy and is excellent in storage stability of an image area.

As a result of intensive studies by the present inventors, a heat-sensitive recording layer provided with a heat-sensitive coloring layer containing a colorless or light-colored basic colorless dye and an organic developer as main components on a support, the heat-sensitive coloring layer comprises A mixture of 4-methyl-4′-hydroxydiphenylsulfone and 4-methyl-2′-hydroxydiphenylsulfone as an organic developer, and at least one compound represented by the following general formula (1) as a sensitizer It was achieved by containing.

（式中、Ｘは酸素原子又は硫黄原子を示し、Ｙは炭素数１〜６の直鎖又は分岐のアルキル基を示し、Ｒ１，Ｒ２はそれぞれ水素原子、ハロゲン原子、炭素数１〜６のアルキル基を示す。）

(In the formula, X represents an oxygen atom or a sulfur atom, Y represents a linear or branched alkyl group having 1 to 6 carbon atoms, and R1 and R2 are a hydrogen atom, a halogen atom, and an alkyl having 1 to 6 carbon atoms, respectively. Group.)

  According to the present invention, a thermal printer that needs to form a high-density and high-definition image with a small amount of energy, such as a miniaturized thermal printer, a high-speed recording type thermal printer, etc. A high-density and high-definition image can be obtained, and a heat-sensitive recording material excellent in storage stability (heat resistance and water resistance) of the image area can be obtained.

  In the present invention, the thermosensitive coloring layer is a mixture of 4-methyl-4′-hydroxydiphenylsulfone and 4-methyl-2′-hydroxydiphenylsulfone as an organic developer, and represented by the general formula (1) as a sensitizer. By containing at least one of the above compounds, a high-density and high-definition image can be obtained even with a minute amount of thermal energy, and a heat-sensitive recording material excellent in storage stability (heat resistance and water resistance) of the image area can be obtained. be able to. The reason why this excellent effect can be obtained is considered as follows.

  By mixing 4-methyl-4'-hydroxydiphenylsulfone and 4-methyl-2'-hydroxydiphenylsulfone, a kind of melting point effect phenomenon occurs. In addition, a sulfide or ether compound having a benzene ring, which is structurally similar to 4-methyl-4′-hydroxydiphenylsulfone and 4-methyl-2′-hydroxydiphenylsulfone and having a benzene ring, is increased. By using as a sensitizer, the compatibility of the developer and sensitizer is improved. For this reason, it is presumed that a high-density and high-definition image can be obtained even with a minute energy. Furthermore, when 4-methyl-4'-hydroxydiphenylsulfone and 4-methyl-2'-hydroxydiphenylsulfone are mixed, it is in a kind of buffer state, and an image due to external factors (heat, humidity, etc.). It is presumed that fading of the part is prevented.

  In order to obtain the heat-sensitive recording material of the present invention, a basic colorless dye, a mixture of 4-methyl-4′-hydroxydiphenylsulfone and 4-methyl-2′-hydroxydiphenylsulfone, and the general formula (1) are used. Mixing a dispersion in which at least one compound is dispersed together with a binder, adding a filler and other necessary additives to prepare a thermosensitive coloring layer coating solution, coating and drying on a substrate to form a thermosensitive coloring layer By doing so, the heat-sensitive recording material of the present invention can be produced.

  In the present invention, at least one compound represented by the general formula (1) is 0 for 1 part by weight of a mixture of 4-methyl-4′-hydroxydiphenylsulfone and 4-methyl-2′-hydroxydiphenylsulfone. It is desirable to contain about 1 to 5 parts by weight, and more preferably 0.5 to 2 parts by weight. The amount of at least one compound represented by the general formula (1) is less than 0.1 parts by weight per 1 part by weight of a mixture of 4-methyl-4'-hydroxydiphenylsulfone and 4-methyl-2'-hydroxydiphenylsulfone If it is, it is difficult to obtain high color development sensitivity, and if it exceeds 5 parts by weight, the heat resistance of the heat-sensitive recording material (heat-sensitive color development layer) is lowered, and the print residue is increased.

  As the leuco coloring-type basic leuco dye used in the present invention, those known in the conventional pressure-sensitive or thermal recording paper field can be used, and are not particularly limited. Compounds, fluoran compounds, fluorene compounds, divinyl compounds and the like are preferable. Specific examples of typical colorless or light-colored dyes (dye precursors) are shown below. These dye precursors may be used alone or in combination of two or more.

<Triphenylmethane leuco dye>
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone)
3,3-bis (p-dimethylaminophenyl) phthalide (also known as malachite green lactone)
<Fluoran leuco dye>
3-diethylamino-6-methylfluorane 3-diethylamino-6-methyl-7-anilinofluorane 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane 3-diethylamino-6-methyl -7-chlorofluorane 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3-diethylamino-6-methyl-7- (o-chloroanilino) fluorane 3-diethylamino-6-methyl- 7- (p-chloroanilino) fluorane 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluorane 3-diethylamino-6-methyl-7- (m-methylanilino) fluorane 3-diethylamino-6-methyl- 7-n-octylanilinofluorane 3-diethylamino- 6-methyl-7-n-octylaminofluorane 3-diethylamino-6-methyl-7-benzylaminofluorane 3-diethylamino-6-methyl-7-dibenzylaminofluorane 3-diethylamino-6-chloro-7 -Methylfluorane 3-diethylamino-6-chloro-7-anilinofluorane 3-diethylamino-6-chloro-7-p-methylanilinofluorane 3-diethylamino-6-ethoxyethyl-7-anilinofluorane 3-diethylamino-7-methylfluorane 3-diethylamino-7-chlorofluorane 3-diethylamino-7- (m-trifluoromethylanilino) fluorane 3-diethylamino-7- (o-chloroanilino) fluorane 3-diethylamino- 7- (p-chloroanilino) fluorane -Diethylamino-7- (o-fluoroanilino) fluorane 3-diethylamino-benzo [a] fluorane 3-diethylamino-benzo [c] fluorane 3-dibutylamino-6-methyl-fluorane 3-dibutylamino-6-methyl- 7-anilinofluorane 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluorane 3-dibutylamino-6-methyl-7- (o-chloroanilino) fluorane 3-dibutylamino-6 -Methyl-7- (p-chloroanilino) fluorane 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluorane 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) Fluorane 3-dibutylamino-6-methyl-chlorofluorane 3-dibutyla Mino-6-ethoxyethyl-7-anilinofluorane 3-dibutylamino-6-chloro-7-anilinofluorane 3-dibutylamino-6-methyl-7-p-methylanilinofluorane 3-dibutylamino -7- (o-chloroanilino) fluorane 3-dibutylamino-7- (o-fluoroanilino) fluorane 3-di-n-pentylamino-6-methyl-7-anilinofluorane 3-di-n-pentyl Amino-6-methyl-7- (p-chloroanilino) fluorane 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluorane 3-di-n-pentylamino-6-chloro-7- Anilinofluorane 3-di-n-pentylamino-7- (p-chloroanilino) fluorane 3-pyrrolidino-6-methyl-7-anilino Fluorane 3-piperidino-6-methyl-7-anilinofluorane 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluorane 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-xylamino) -6-methyl- 7- (p-chloroanilino) fluorane 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-isoamylamino) -6-methyl-7-ani Linofluorane 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilinofluorane 3- (N-ethyl-N-tetrahydrofurfurylamino) -6 Methyl-7-anilinofluorane 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-ethoxypropylamino) -6-methyl-7 -Anilinofluorane 3-cyclohexylamino-6-chlorofluorane 2- (4-oxahexyl) -3-dimethylamino-6-methyl-7-anilinofluorane 2- (4-oxahexyl) -3- Diethylamino-6-methyl-7-anilinofluorane 2- (4-oxahexyl) -3-dipropylamino-6-methyl-7-anilinofluorane 2-methyl-6-p- (p-dimethylamino) Phenyl) aminoanilinofluorane 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluorane 2-chloro-3-methyl-6 p- (p-phenylaminophenyl) aminoanilinofluorane 2-chloro-6-p- (p-dimethylaminophenyl) aminoanilinofluorane 2-nitro-6-p- (p-diethylaminophenyl) aminoani Linofluorane 2-amino-6-p- (p-diethylaminophenyl) aminoanilinofluorane 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane 2-phenyl-6-methyl-6 -P- (p-phenylaminophenyl) aminoanilinofluorane 2-benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane 2-hydroxy-6-p- (p-phenylaminophenyl) Aminoanilinofluorane 3-methyl-6-p- (p-dimethylaminophenyl) amino Nilinofluorane 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluorane 2,4-dimethyl-6-[( 4-Dimethylamino) anilino] -fluorane

<Fluorene leuco dye>
3,6,6'-tris (dimethylamino) spiro [fluorene-9,3'-phthalide]
3,6,6'-tris (diethylamino) spiro [fluorene-9,3'-phthalide]

<Divinyl leuco dye>
3,3-bis- [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrabromophthalide 3,3-bis- [2- ( p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene -2-yl] -4,5,6,7-tetrabromophthalide 3,3-bis- [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl]- 4,5,6,7-tetrachlorophthalide <Others>
3- (4-Diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-diethylamino-2-ethoxyphenyl) -3- (1 -Octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4- Azaphthalide 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide 3,6-bis (diethylamino) fluorane-γ- (3′-nitro) anilinolactam 3,6-bis (diethylamino) Fluorane-γ- (4′-nitro) anilinolactam 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminopheny L) -ethenyl] -2,2-dinitrileethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2-β -Naphthoylethane 1,1-bis- [2 ', 2', 2 ", 2" -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,2-diacetylethane bis- [2,2,2 '2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

  As the sensitizer used in the present invention, 1,2-di- (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 1,2-di (3-methylphenoxy) ethylene, 1,2- A sulfide or ether compound having a benzene ring such as diphenoxyethylene is preferred, and among these, 1,2-di- (3-methylphenoxy) ethane is preferred. In addition, one type or two or more types of conventionally known sensitizers can be used in combination as long as the desired effects on the above problems are not impaired. Such sensitizers include saturated fatty acid monoamide, ethylene bisamide, montanic acid wax, polyethylene wax, p-benzylbiphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 4,4 ′. -Ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, bis [2- (4-methoxy-phenoxy) ethyl] ether, methyl p-nitrobenzoate, dibenzyl oxalate, di-oxalate (p- Chlorobenzyl), di (p-methylbenzyl) oxalate, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1- Hydroxy-2-naphthoic acid phenyl ester Ter, 4- (m-methylphenoxymethyl) biphenyl, 1,2-bis (phenoxymethyl) benzene, paratoluenesulfonamide, and orthotoluenesulfonamide can be exemplified, but are not particularly limited thereto. .

  As the binder used in the present invention, fully saponified polyvinyl alcohol having a polymerization degree of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, and others Modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and cellulose derivatives such as ethyl cellulose, acetyl cellulose, polyvinyl chloride, polyvinyl acetate, poly Acrylamide, polyacrylic ester, polyvinyl butyllar, polystyrose and their copolymers, polyamide resin, silico Resins, petroleum resins, terpene resins, ketone resins, and the Khumalo resin. These polymer substances are used by dissolving them in solvents such as water, alcohol, ketones, esters, hydrocarbons, etc., and are used in the state of being emulsified or pasted in water or other media to achieve the required quality. It can also be used in combination.

  Further, in the present invention, 4,4′-butylidene (6-tert-butyl-3-methylphenol) is used as an image stabilizer exhibiting the oil resistance effect of a recorded image and the like within a range that does not impair the desired effect on the above problems. ), 2,2'-di-t-butyl-5,5'-dimethyl-4,4'-sulfonyldiphenol, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) Butane, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4-benzyloxy-4- (2,3-epoxy-2-methylpropoxy) diphenylsulfone, epoxy Resin, 4,4′-bis (3- (phenoxycarbonylamino) methylphenylureido) diphenylsulfone (trade name: UU, manufactured by Asahi Kasei Corporation), 4,4′-bisf Nord S and diethylene glycol polycondensate: may be added (trade name D-90, manufactured by Nippon Soda Co., Ltd.) and the like.

  Examples of the filler used in the present invention include inorganic or organic fillers such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide. In addition, lubricants such as waxes, benzophenone and triazole ultraviolet absorbers, water resistance agents such as glyoxal, dispersants, antifoaming agents, antioxidants, fluorescent dyes, and the like can be used.

  General amounts of basic colorless dye, developer, filler, binder and the like used in the heat-sensitive recording material of the present invention are 0.1 to 2 parts of basic colorless dye with respect to 1 part of developer. Filler 0.5-4 parts, binder is 5-25% in the total solids. In addition, other components necessary for the required quality can be added as appropriate, and there is no particular limitation on the type and blending amount.

  The desired thermosensitive recording sheet can be obtained by coating the coating liquid having the above composition on an arbitrary support such as paper, recycled paper, synthetic paper, film, plastic film, foamed plastic film, and nonwoven fabric. Moreover, you may use the composite sheet which combined these as a support body.

  Furthermore, an overcoat layer such as a polymer substance can be provided on the heat-sensitive color developing layer for the purpose of enhancing the storage stability. In addition, an undercoat layer such as a polymer material containing a filler can be provided under the heat-sensitive layer for the purpose of increasing the color development sensitivity. The aforementioned organic developer, basic colorless dye, and material to be added as necessary are finely divided to a particle size of several microns or less by a pulverizer such as a ball mill, attritor, sand glider or an appropriate emulsifier, and a binder. Depending on the purpose, various additive materials are added to obtain a coating solution. The application means is not particularly limited, and can be applied according to well-known conventional techniques. For example, an off-machine coating machine equipped with various coaters such as an air knife coater, a rod blade coater, a bill blade coater, and a roll coater, A machine coater is appropriately selected and used.

  Hereinafter, the present invention will be described by way of examples, but the present invention is not limited thereto. In the description, parts indicate parts by weight.

[Example 1]
For each material of the dye and developer, a dispersion having the following composition was prepared in advance, and wet grinding was performed with a sand grinder until the average particle size became 0.5 microns.
<Developer dispersion>
1/1 mixture of 4-methyl-4'-hydroxydiphenylsulfone and 4-methyl-2'-hydroxydiphenylsulfone (trade name DS-2000, Yamamoto Kasei)
6.0 parts 10% polyvinyl alcohol aqueous solution 18.8 parts water 11.2 parts <sensitizer dispersion>
1,2-di- (3-methylphenoxy) ethane 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts <dye dispersion>
3-Di-n-butylamino-6-methyl-7-anilinofluorane
(ODB2) 3.0 parts 10% aqueous polyvinyl alcohol solution 6.9 parts Water 3.9 parts The following composition was mixed to obtain a heat-sensitive layer coating solution. This coating solution is applied and dried on a high-quality paper having a basis weight of 50 g / m ^{2 so} that the coating amount after drying becomes 6 g / m ^2, and processed so that the Beck smoothness becomes 200 to 600 seconds with a super calendar, A heat-sensitive recording material was obtained.
Developer dispersion 36.0 parts Sensitizer dispersion 36.0 parts Dye dispersion 13.8 parts Kaolin clay 50% dispersion 26.0 parts Zinc stearate 30% dispersion 6.7 parts

[Comparative Example 1]
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 1,2-di- (3-methylphenoxy) ethane in the sensitizer dispersion was changed to stearamide.

[Comparative Example 2]
In Example 1, a 1/1 mixture of 4-methyl-4′-hydroxydiphenylsulfone and 4-methyl-2′-hydroxydiphenylsulfone (trade name DS-2000, Yamamoto Kasei) in the developer dispersion was used. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 4'-dihydroxydiphenylsulfone was used.

[Color development sensitivity]
Using TH-PMD manufactured by Okura Electric Co., Ltd., printing was performed on the created thermal recording medium with an applied energy of 0.34 mJ / dot. The image density after printing and after the quality test was measured with a Macbeth densitometer (using an amber filter).

[Heat-resistant]
Using TH-PMD manufactured by Okura Electric Co., Ltd., a sample piece printed with an applied energy of 0.34 mJ / dot was left in a 60 ° C. environment for 24 hours, and then the Macbeth density of the image portion and the background portion was measured.

[Moisture resistance]
Using TH-PMD manufactured by Okura Electric Co., Ltd., leaving the image area printed at 0.34 mJ / dot for 24 hours in an environment of 60 ° C and 90%, then measuring the density of the image area and the background area with a Macbeth densitometer did.

[Plasticizer]
A PVC wrap (Mitsui Chemicals High Wrap KMA) is wrapped around a paper tube in a single layer, and a sample piece printed with an applied energy of 0.34 mJ / dot is pasted thereon using a TH-PMD made by Okura Electric Co., Ltd. Further, a product obtained by wrapping a vinyl chloride wrap on top of this was allowed to stand at 23 ° C. for 24 hours, and then the density of the image portion and the background portion was measured with a Macbeth densitometer.

  As is apparent from the table, Example 1 of the present invention is excellent in image storage stability such as color development sensitivity, heat resistance, moisture resistance, and plasticizer resistance. On the other hand, good quality cannot be obtained for the heat-sensitive recording material of Comparative Example 1 using a sensitizer other than that specified in the present invention and Comparative Example 2 using a developer other than that specified in the present invention.

Claims (2)

A thermosensitive recording medium comprising a thermosensitive color-developing layer comprising a colorless or light-colored basic colorless dye and an organic developer as main components on a support, wherein the thermosensitive color-developing layer is 4-methyl- A heat-sensitive product comprising a mixture of 4'-hydroxydiphenylsulfone and 4-methyl-2'-hydroxydiphenylsulfone, and at least one compound represented by the following general formula (1) as a sensitizer. Recorded body.

(In the formula, X represents an oxygen atom or a sulfur atom, X represents a linear or branched alkyl group having 1 to 6 carbon atoms, and R1 and R2 are a hydrogen atom, a halogen atom, and an alkyl having 1 to 6 carbon atoms, respectively. Group.) The heat-sensitive recording material according to claim 1, wherein the sensitizer is 1,2-di (3-methylphenoxy) ethane.