JPH0725141A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material especially reduced in background fog and obtaining a recording image excellent in light stability and stability with the elapse of time. CONSTITUTION:In a thermal recording material wherein a thermal recording layer containing a colorless or light-colored basic dye and a coupler is provided on a support, a 4-hydroxydiphenylsulfone derivative being the coupler and 2,5-di(tert-butyl)hydroquinone or 2,5-di(tert-amyl)hydroquinone being an oxidation inhibitor are added to the thermal recording layer.

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 which is particularly free from background fog and has excellent light stability and temporal stability of recorded images.

[0002]

2. Description of the Related Art A heat-sensitive recording material which utilizes a coloring reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to bring both coloring substances into contact with each other by heat to obtain a recorded image is often used. Are known. Such a thermal recording material is relatively inexpensive,
Also, since the recording equipment is compact and its maintenance is easy,
It is used not only as a recording medium for facsimiles and various computers, but also in a wide range of fields.

[0003] As one of the fields of use thereof, P in retail stores
Thermal recording paper for an OS (point of sales) system can be mentioned. Along with the expansion of the system, the uses attached to products are increasing. However, depending on the product, the attached thermosensitive recording paper is often exposed to room light or sunlight, which has the drawback that the recorded image is easily discolored. Conventionally, in order to improve the light resistance of a recorded image, a method of adding an antioxidant, an ultraviolet absorber or the like into a heat-sensitive recording layer has been disclosed in JP-A-49-54040 and JP-A-50-104.
No. 650, Japanese Patent Application Laid-Open No. 50-149353 and the like, and in Japanese Patent Application Laid-Open No. 60-48395, 2,5-di (tert-butyl) hydroquinone and 2,5-dicarboxylic acid are used as antioxidants. Although a heat-sensitive recording material using di (tert-amyl) hydroquinone is described, there are problems in background fog and stability of recorded image with time.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium which has a particularly low background fog and which is excellent in light stability and temporal stability of recorded images.

[0005]

The recorded image of a heat-sensitive recording material using a 4-hydroxydiphenylsulfone derivative as a coloring agent for a colorless or light-colored basic dye is excellent in stability over time, but is light-stable. Is inferior to. Therefore, the present inventors have found that in a heat-sensitive recording material in which a thermosensitive recording layer containing a colorless or light-colored basic dye and a color-developing agent is provided on a support, 4-hydroxy as a color-developing agent is contained in the heat-sensitive recording layer. Diphenyl sulfone derivative and 2,5-di (tert-butyl) hydroquinone or 2,5-di (te as an antioxidant
rt-amyl) by containing at least one of hydroquinone, it is found that the above objects are achieved,
The present invention has been completed.

[0006]

The present invention provides a thermosensitive recording layer containing a colorless or pale basic dye and a 4-hydroxydiphenylsulfone derivative as a coloring agent, or 2,5-di (tert-butyl) hydroquinone as an antioxidant or 2,5-di (te
By adding rt-amyl) hydroquinone, the light resistance of the recorded image was specifically improved.

The amounts of the specific antioxidant and the 4-hydroxydiphenyl sulfone derivative used are not particularly limited, but the basic dye 100 is generally used.
10 to 5 for specific antioxidant with respect to parts by weight.
00 parts by weight, preferably 20 to 200 parts by weight, 50 to 50 for the 4-hydroxydiphenyl sulfone derivative
It is desirable to use 0 part by weight, preferably 100 to 300 parts by weight.

Specific examples of the 4-hydroxydiphenyl sulfone derivative used as a colorant include, for example, 2,
4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4 '
-Isopropyloxydiphenyl sulfone, bis (3-
Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-3 ', 4'-tetramethylenediphenylsulfone, 3,4-dihydroxydiphenylsulfone, 3,4
-Dihydroxy-4'-methyldiphenyl sulfone and the like are exemplified. Of course, it is not limited to these,
If necessary, two or more kinds can be used in combination.

Further, various other known colorants may be used as long as the effects of the present invention are not impaired. Examples of such colorants include inorganic clay such as activated clay, attapulgite, colloidal silica and aluminum silicate. Substance, 4-tert
-Butylphenol, 4-hydroxydiphenoxide,
α-naphthol, β-naphthol, 4-hydroxyacetophenol, 4-tert-octylcatechol, 2,
2'-dihydroxydiphenol, 4,4'-isopropylidene bis (2-tert-butylphenol), 4,
4'-sec-butylidene diphenol, 4-phenylphenol, 4,4'-isopropylidene diphenol (bisphenol A), 2,2'-bis (4-hydroxyphenyl) -4-methylpentane, 2,2 ' -Methylenebis (4-chlorophenol), hydroquinone,
4,4'-cyclohexylidene diphenol, 4,4 '
-Dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4
4'-trihydroxybenzophenone, 2,2 ', 4
4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate,
Propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, 4
-Chlorophenyl hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, -p-chlorobenzyl 4-hydroxybenzoate, -p-methoxybenzyl 4-hydroxybenzoate,
Phenolic compounds such as novolac type phenol resin and phenol polymer, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-
Aromatic carboxylic acids such as 4-hydrobenzoic acid and 3,5-dimethyl-4-hydroxybenzoic acid, bis (3-tert
-Butyl-4-hydroxy-6-methylphenyl) sulfide, bis (2-methyl-4-hydroxy-6-tert)
-Butylphenyl) sulfide and other sulfide derivatives,
Furthermore, salts of these phenolic compounds, aromatic carboxylic acids and the like with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin and nickel, and organic acid such as antipyrine complex of zinc thiocyanate. Examples include substances.

In the present invention, various known colorless or light-colored basic dyes can be used as the basic dye constituting the heat-sensitive recording layer. Examples thereof include the following. Three
3-bis (p-dimethylaminiphenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl)
-6-Dimethylaminophthalide, 3-diethylamino-
7-dibenzylamino-benzo [a] fluorane, 3-
(N-Ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,6- Bis (diethylamino) fluorane-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-
6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl) -N-cyclohexyl) amino-
6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (N-pentyl) amino-6-methyl-
7-anilinofluorane, 3-diethylamino-7-
(O-chlorophenylamino) fluorane, 3-di (n
-Butyl) amino-7- (o-chlorophenylamino)
Fluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-chlorophenylamino) fluorane,
3-diethylamino-7- (o-fluorophenylamino) fluorane, 3-di (n-butyl) amino-7-
(O-Fluorophenylamino) fluorane, 3- (N
-Ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino)-
6-methyl-7- (p-toluidino) fluorane, 3-
(N-ethyl-N-furfurylamino) -6-methyl-
7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-methyl-N
-N-propylamino) -6-methyl-7-anilinofluorane, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -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, 3,3-bis [1,1
-Bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3-p
-(P-Dimethylaminoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6 '
-(N-cyclohexyl-N-methylamino) -3'-
Methyl spiro [phthalide-3,9'-xanthene-2 '
Examples include -ylamino] phenyl} propane and 3,6,11-tri (dimethylamino) fluorane. Among them, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane is particularly preferable because it has less background fog.
Of course, it is not limited to these, and two or more kinds may be used in combination as required. When the basic dye as described above is used in combination, it is desirable to adjust the ratio of the dye as described above to 20% by weight or less in the total basic dye.

In the present invention, a coating solution containing a basic dye, a coloring agent, an antioxidant and the like is generally prepared by using water as a dispersion medium and stirring with a ball mill, attritor, vertical or horizontal sand mill, colloid mill, etc. Dye,
It is prepared by dispersing a color former and a heat-fusible substance together or separately.

In such coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy group-modified polyvinyl alcohol, sulfo group-modified polyvinyl alcohol, acetoacetyl group-modified are usually used as binders. Polyvinyl alcohol, various modified polyvinyl alcohol such as silicone modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer A coalescing salt, a styrene / butadiene copolymer emulsion, a urea resin, a melamine resin, an amide resin and the like are blended in an amount of 5 to 30% by weight, preferably 8 to 25% by weight, based on the total solid content. Of course, these binders may be used in combination of two or more.

Further, various auxiliary agents can be added to the coating liquid, for example, 2,2'-methylenebis (4,6-
Mixture of sodium salt of di-tert-butylphenyl) phosphate and magnesium silicate, dioctyl sulfosuccinic acid sodium salt, dodecylbenzenesulfonic acid sodium salt, lauryl alcohol sulfate / sodium salt, dispersant for fatty acid metal salt, benzophenone system,
Examples thereof include cyanoacrylate-based and hydroxybenzoate-based ultraviolet absorbers, defoaming agents, fluorescent dyes, and coloring dyes.

Further, stearic acid ester wax, polyethylene wax, carnauba wax, microcrystalline wax, so as to prevent the thermal recording material from sticking due to contact with recording equipment or recording head.
It is also possible to add a dispersion liquid or emulsion of carboxy-modified paraffin wax, zinc stearate, calcium stearate or the like.

In addition, kaolin, clay, talc, calcium carbonate,
Magnesium carbonate, calcined clay, titanium oxide, diatomaceous earth,
Inorganic pigments such as particulate anhydrous silica and activated clay, organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch granules can also be added.

Further, a sensitizer may be used in combination according to the purpose. Specific examples thereof include fatty acid amides such as stearic acid amide, stearic acid methylenebisamide, oleic acid amide, palmitic acid amide, and coconut fatty acid amide. 4,4'-butylidene bis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-
Methyl-4-hydroxy-5-tert-butylphenyl)
Butane, hindered phenols such as 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, p-benzylbiphenyl, p- (4
-Tolyloxy) biphenyl, 1,5-bis (4-methoxyphenoxy) -3-oxa-pentane, 1,2-bis (phenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,2- Bis (3-methylphenoxy) ethane, 1- (2-methylphenoxy) -2- (4
-Methoxyphenoxy) ethane, ethers such as 2-naphtholbenzyl ether, dibenzyl terephthalate, 1-hydroxy-2-naphthoic acid phenyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, oxalic acid Examples thereof include esters such as di (4-chlorobenzyl) ester.

A storability improver may be added to further enhance the storability of the recorded image. Specific examples of such a shelf life improver include, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,
2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-)
tert-butylphenol), 4,4'-thiobis (3-
Methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol),
4,4'-thiobis (2-methylphenol), 4,
4'-thiobis (2,6-dimethylphenol), 4,
4'-thiobis (2,6-di-tert-butylphenol), 2,2'-thiobis (4-tert-octylphenol), 2,2'-thiobis (3-tert-octylphenol), 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, 2,2-bis (4-hydroxy-3,
5-dibromophenyl) propane, 2,2-bis (4-
Hydroxy-3,5-dichlorophenyl) propane,
Hindered phenolic compounds such as 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane,
1,4-Diglycidyloxybenzene, 4-benzyloxy-4 '-(2-methyl-2,3-epoxypropyloxy) diphenyl sulfone, 4,4'-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, cresol novolak Type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin and other epoxy compounds, N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6-di-tert. -Butylphenyl) sodium phosphate, N, N'-di-2-naphthyl-p-phenylenediamine, 4,4'-bis (ethyleneiminecarbonylamino) diphenylmethane and the like.

In the heat-sensitive recording material of the present invention, the method for forming the recording layer is not particularly limited. It can be formed according to a well-known and conventional technique. For example, the coating liquid for the heat-sensitive recording layer is coated on a support with an appropriate coating device such as an air knife coater, a blade coater, a bar coater, a die coater, a gravure coater, and a curtain coater, and dried to form a recording layer.

The coating amount of the coating liquid is also not particularly limited, and is generally 1.0 to 10 g / m on a dry weight basis.
² , preferably in the range of 1.5 to 7 g / m ² . As the support, paper, plastic film, synthetic paper and the like are used, but paper is most preferably used in terms of cost and coating suitability. The use of synthetic paper is more preferable because of its high color density.

In the present invention, a protective layer may be formed on the heat-sensitive layer to enhance the storage stability. Examples of the water-soluble or water-dispersible polymer used for forming the protective layer include various binders as described above. Among them, acetoacetyl group-modified polyvinyl alcohol and carboxyl group-modified polyvinyl alcohol are water-resistant. It is particularly preferably used in combination with an agent and a cross-linking agent to form a strong film.

A pigment may be added to the protective layer, if necessary, in order to further improve printability and sticking. Specific examples thereof include calcium carbonate,
Inorganic pigments such as zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, kaolin, clay, calcined kaolin, colloidal silica, styrene microballs, nylon powder, polyethylene powder, urea Examples include formalin resin fillers and organic pigments such as raw starch particles.
The amount used is generally 5 to 100 parts by weight of the resin component.
It is desirable to adjust within the range of about 500 parts by weight.

Furthermore, in the coating liquid for forming the protective layer, zinc stearate, calcium stearate,
Lubricants such as polyethylene wax, carnauba wax, paraffin wax, ester wax, etc., surfactants such as sodium dioctylsulfosuccinate (dispersant, wetting agent),
Various auxiliaries such as antifoaming agents, potassium alum, water-soluble polyvalent salts such as calcium acetate, etc. may be appropriately added. Also, to further improve water resistance, glyoxal, boric acid,
Hardeners such as dialdehyde starch and epoxy compounds can also be added.

The coating liquid for forming the protective layer is generally prepared by using water as a dispersion medium. The coating solution for protective layer thus prepared is coated on the thermosensitive recording layer by a suitable coating device. However, if the coating amount exceeds 10 g / m ² in dry weight, the recording sensitivity of the thermosensitive recording medium may be significantly lowered. Therefore, it is generally 0.1 to 10 g / m ² , preferably 0.5 to 7 g.
It is desirable to adjust in the range of about / m ² .

If desired, a protective layer may be provided on the back side of the thermosensitive recording medium to further improve the storability. Further, it is possible to provide an undercoat layer on the support or to apply a super calender after coating each layer, and to apply a pressure-sensitive adhesive to the back surface of the recording material to process it into an adhesive label. The publicly known technology can be added as needed.

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively, unless there is particular notice.

[0026]

Example 1 Formation of Intermediate Layer Calcined clay [trade name: Ansilex, manufactured by EMC] 1
00 parts, styrene-butadiene copolymer latex (solid content: 50%) 15 parts, polyvinyl alcohol 10%
A composition comprising 30 parts of an aqueous solution and 200 parts of water was mixed and stirred to prepare a coating liquid for intermediate layer. The obtained coating liquid is 7
An intermediate layer was formed by coating and drying on a high-quality paper of 0 g / m ² such that the coating amount after drying was 7 g / m ² .

Preparation of Solution A 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 20 parts of 1,2-bis (3-methylphenoxy) ethane, 5% aqueous solution of methylcellulose 1
A composition consisting of 0 part and 50 parts of water was pulverized with a sand mill until the average particle size became 0.8 μm.

Preparation of Solution B 4-Hydroxy-4′-isopropyloxydiphenylsulfone 30 parts, 5% aqueous solution of methylcellulose 10
Parts and 50 parts of water were pulverized with a sand mill until the average particle size was 1.2 μm.

Preparation of Solution C A composition consisting of 10 parts of 2,5-di (tert-butyl) hydroquinone, 5 parts of a 5% aqueous solution of methylcellulose, and 15 parts of water was pulverized with a sand mill until the average particle size became 1.5 μm. did.

Formation of Thermosensitive Recording Layer 90 parts of solution A, 90 parts of solution B, 30 parts of solution C, 160 parts of 10% aqueous solution of polyvinyl alcohol, light calcium carbonate 1
0 part, 20 parts of fine particle silicon oxide, 30 parts of zinc stearate
% Dispersion liquid and 100 parts water were mixed and stirred to obtain a coating liquid for the heat-sensitive recording layer. The resulting coating liquid was applied onto the above-mentioned intermediate layer so that the dry weight was 3 g / m ² , dried and then subjected to a super calender treatment to obtain a thermosensitive recording medium.

[0031]

Example 2 In preparation of solution B, 4-hydroxy-4 '
-2,4'-dihydroxydiphenyl sulfone was used instead of isopropyloxydiphenyl sulfone, and 2,5-di (tert-amyl) hydroquinone was used instead of 2,5-di (tert-butyl) hydroquinone in the liquid C preparation. A thermal recording material was obtained in the same manner as in Example 1 except that the thermal recording material was used.

[0032]

Example 3 In preparation of solution A, 3-di (n-butyl)
Amino-6-methyl-7-anilinofluoranno Same as Example 1 except 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran was used instead of amino-6-methyl-7-anilinofluoranno. A thermosensitive recording material was obtained.

[0033]

Example 4 In preparation of solution A, 3-di (n-butyl)
Amino-6-methyl-7-anilinofluoranno was carried out except that 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluoran was used instead. A thermal recording material was obtained in the same manner as in Example 1.

[0034]

[Comparative Example 1] 4-hydroxy-4 'in preparation of solution B
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 4,4′-isopropylidenediphenol was used instead of isopropyloxydiphenylsulfone.

[0035]

Comparative Example 2 Example 1 was repeated except that 2,2'-methylenebis (4-methyl-6-tert-butylphenol) was used in place of 2,5-di (tert-butyl) hydroquinone in the preparation of solution C. A thermosensitive recording medium was obtained in the same manner as described above.

[0036]

[Comparative Example 3] In the preparation of solution C, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane was used instead of 2,5-di (tert-butyl) hydroquinone. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the heat-sensitive recording material was used.

[0037]

Comparative Example 4 A thermosensitive recording medium was obtained in the same manner as in Example 2 except that the liquid C was not used.

The following seven types of heat-sensitive recording papers thus obtained were evaluated, and the results are shown in Table 1.

Recording Density A thermal recording material evaluation machine [trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.] was used to record on recording paper with an applied energy of 0.2 mJ / dot, and the color density of the obtained recorded image was calculated as Macbeth density. Total [R
D-914 type, manufactured by Macbeth Co., Ltd.] It was measured in visual mode. Background Fog In order to evaluate the degree of background fogging, the whiteness of the recording layer side was measured with a Hunter whiteness meter. Light resistance of recorded image After the thermal recording paper after recording was stuck to the window side on the south side and kept for 10 days, the density of the recorded image was measured with a Macbeth reflection densitometer,
The light stability was evaluated. Stability of Recorded Image with Time After the heat-sensitive recording paper after recording was allowed to stand for 7 days under the condition of 40 ° C. and 90% RH, the density of the recorded image was measured with a Macbeth reflection densitometer to evaluate the stability with time.

[0040]

[Table 1]

[0041]

[Effect] As is clear from the results shown in [Table 1], the thermosensitive recording materials obtained in the respective examples of the present invention have less background fog and have excellent light stability and temporal stability of recorded images. It was a thermosensitive recording medium.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Yoshihiro Shimizu Inventor Yoshihiro Shimizu 4-3-1, Jokoji, Amagasaki City, Hyogo Kanzaki Paper Mill Kanzaki Mill

Claims (2)

[Claims] 1. A thermosensitive recording medium comprising a support and a thermosensitive recording layer containing a colorless or light-colored basic dye and a color former, wherein 4-hydroxydiphenylsulfone is used as a color former in the thermosensitive recording layer. 2, as a derivative and antioxidant
5-di (tert-butyl) hydroquinone or 2,5-
A heat-sensitive recording material containing at least one kind of di (tert-amyl) hydroquinone. 2. The thermosensitive recording medium according to claim 1, wherein the basic dye is 3-di (n-butyl) amino-6-methyl-7-anilinofluorane.