JPH0899466A - Heat sensitive recording medium - Google Patents

Abstract

PURPOSE: To obtain a light fast data recording medium which undergoes least discoloration in the bare surface and fading in a recorded image when it is exposed to a fluorescent light or sunlight for a long period of time, by containing a specified phenothiazine derivative and an antioxidant in a heat sensitive recording layer. CONSTITUTION: A heat sensitive recording medium which has a heat sensitive recording layer containing a black leuco color and a colorant on a support, wherein light fastness of a printed part is ensured and bare surface discoloration is reduced by containing a phenothiazine derivative as shown in Formula I and a compound as shown in Furmula II as an antioxidant. In formula I, R1 to R4 represent a 1-4C alkyl group, respectively, R5 an hydrogen atom, a halogen atom, a 1-4C alkyl group or a 1-4C alkoxyl group. In Formula II, R1 represents a hydrogen atom or a methyl group, R2 tert-butyl group tert-amyl group, R3 methyl or tert-amyl group.

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-developing reaction between a black color-forming leuco dye and a color-developing agent, and more particularly to a heat-sensitive recording material excellent in light stability of recorded image and suppression of discoloration of background. It is about the body.

[0002]

2. Description of the Related Art A heat-sensitive recording material is known in which a color image is obtained by contacting both color-forming substances with heat by utilizing a color reaction between a colorless or light-colored leuco dye and an organic or inorganic color developing agent. Has been. Such a thermal recording material is relatively inexpensive,
Since the recording device is compact and easy to maintain, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields. One of the fields of application is the POS (point of sales) of retail stores.
Thermal recording paper for the 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 heat-sensitive recording paper is often exposed to room light or sunlight, which has a 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 or an ultraviolet absorber in the heat-sensitive recording layer has been disclosed in JP-A-49-54040 and JP-A-50-.
Although disclosed in 104650 public information and Japanese Patent Laid-Open No. 60-48395, there are problems in background discoloration (background fogging) and stability of recorded images with time.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material excellent in light resistance, in which discoloration of the background portion and fading of a recorded image upon exposure to a fluorescent lamp or sunlight for a long time is extremely small. Is to provide.

[0005]

Means for Solving the Problems The present inventors have
A heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a black color-forming leuco dye and a color former, wherein the heat-sensitive recording layer contains a phenothiazine derivative represented by the following general formula (1). To improve the light resistance of the printed part, and to suppress the background fog of the phenothiazine derivative by combining the compound represented by the following general formula (2) as an antioxidant, and to suppress the discoloration of the background part. The present invention has been completed and the present invention has been completed.

[0006]

[Chemical 3]

[In the general formula (1), R _{1 to} R ₄ each represent a C _{1 to} C ₄ alkyl group, and R ₅ represents a hydrogen atom, a halogen atom, a C _{1 to} C ₄ alkyl group or C ₁
Is a C ₄ -alkoxyl group. ]

[0008]

[Chemical 4]

[In the general formula (2), R ₁ represents a hydrogen atom or a methyl group. R ₂ is a tert-butyl group or te
An rt-amyl group is shown. R ₃ represents a methyl group or a tert-amyl group. ]

[0010]

According to the present invention, a phenothiazine derivative represented by the general formula (1) and an antioxidant represented by the general formula (2) are contained in a heat-sensitive recording layer containing a black color-forming leuco dye and a coloring agent. The addition of the compound specifically improved the discoloration of the background and the light resistance of the recorded image.

The amount of the specific antioxidant and phenothiazine derivative used is not particularly limited, but generally 1 to 200 parts by weight of the specific antioxidant per 100 parts by weight of the all-black coloring leuco dye. Parts, preferably 1 to 100 parts by weight, and the phenothiazine derivative is 0.
It is desirable to use 1 to 50 parts by weight, preferably 1 to 10 parts by weight.

Examples of the black color-forming leuco dye used in the present invention include various known colorless or light-colored black color-forming leuco dyes. As a specific example, for example, 3- (N-
Ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane, 3-dimethylamino-7 (m-trifluoromethyl) anilinofluorane, 3-pyrrolidino-6-methyl-7-nitinofluorane, 3 -Diethylamino-7- (m-trifluoromethyl) anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-Nn-hexylamino) -6-methyl -7-anilinofluorane, 3- (N
-Ethyl-N-isoamylamino) -7- (o-chloroanilino) fluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3-di (n-).
Butyl) amino-6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino) -6-methyl-7-anilinofluorane, 3-
[N- (3-ethoxypropyl) -N-methylamino)
-6-methyl-7-anilinofluorane, 3- (N-n
-Hexyl-N-ethylamino) -7- (o-chloroanilino) fluorane, 3-di (n-butyl) amino-6
-Methoxy-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7 -(P-toluidino) fluorane, 3-diethylamino-6-methyl-7- (2,4-xylidino) fluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) ) Amino-6-methyl-7-m-toluidino, 3-diethylamino-6-
Methyl-7-m-toluidino, fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3
-Di (n-butyl) amino-7- (o-chloroanilino) fluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-
6-Methyl-7-anilinofluorane, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-
7- (o-fluoroanilino) fluorane, 3-di (n
-Butyl) amino-7- (o-fluoroanilino) fluorane, 3- (N-ethyl-N-cyclopentylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7- Anilino Fluoran, 3
-Diethylamino-6-chloro-7- (pn-butylanilino) fluorane, 3- (N-cyclohexyl-N)
-Methylamino) -6-methyl-7-anilinofluorane, 3- (Nn-butyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane, 3-di (n-butyl) Amino-6-methyl-7- (p-chloroanilino) fluorane, 3-pyridino-6-methyl-7
-Anilinofluorane, 3-pyridino-6-methyl-7
-(Pn-butylanilino) fluorane, 3-pyridino-6-methyl-7-anilinofluorane, 3- (N-
Ethyl-N-isobutylamino) -6-methyl-7-anilinofluorane, 3-pyridino-6-methyl-7-p
-Toluidinofluorane, 3-diethylamino-6-methyl-7- (p-ethoxyanilino) fluorane, 3-
(N-methyl-Nn-propylamino) -6-methyl-7-anilinofluorane and the like can be mentioned.

In the present invention, the phenothiazine derivative represented by the general formula (1) used in combination with the fluoran derivative as described above is a dye which produces a blue color tone when used alone, The following compounds and the like are exemplified. 3,7-bis (dimethylamino) -10-
Benzoylphenothiazine, 3,7-bis (diethylamino) -10-benzoylphenothiazine, 3,7-bis (di-n-butylamino) -10-benzoylphenothiazine, 3,7-bis (dimethylamino) -10- (4
-Methylbenzoyl) phenothiazine, 3,7-bis (diethylamino) -10- (4-methylbenzoyl)
Phenothiazine, 3,7-bis (di-n-butylamino) -10- (4-methylbenzoyl) phenothiazine, 3,7-bis (dimethylamino) -10- (4-methoxybenzoyl) phenothiazine, 3,7- Bis (dimethylamino) -10- (4-ethoxybenzoyl) phenothiazine, 3,7-bis (dimethylamino) -10
-(4-chlorobenzoyl) phenothiazine, 3,7-
Bis (dimethylamino) -10- (2-methylbenzoyl) phenothiazine, 3,7-bis (dimethylamino)
-10- (2-methoxybenzoyl) phenothiazine,
3,7-bis (dimethylamino) -10- (2-chlorobenzoyl) phenothiazine, 3,7-bis (di-n-
Butylamino) -10- (4-chlorobenzoyl) phenothiazine, 3-diethylamino-7-dimethylamino-10-benzoylphenothiazine and the like. Among these, the compound represented by 3,7-bis (dimethylamino) -10-benzoylphenothiazine is particularly preferable because the raw material is easily available, the cost is low, and the image storability, especially, the light resistance is excellent. . Of course, it is not limited to these, and two or more kinds may be used in combination as required.

The coating liquid for the heat-sensitive recording layer is generally prepared by using water as a dispersion medium and dispersing with a stirring / pulverizing machine such as a ball mill or a sand mill.

The coating liquid for the heat-sensitive recording layer contains 10 to 10% of the total solid content.
About 40% by weight, and more preferably about 15 to 30% by weight of binders are blended. Specific examples of the binders include methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, polyvinyl alcohol (PVA), carboxy group modified polyvinyl alcohol, sulfonic acid group modified polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, Water-soluble polyacrylic acid, starch and its derivatives, casein, gelatin water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, alkali salt of iso (or diiso) butylene / maleic anhydride copolymer, etc. Or ethylene / vinyl acetate copolymer, polystyrene, polyacrylic acid ester, polyurethane, styrene / butadiene copolymer, carboxylated styrene And butadiene copolymer, styrene / butadiene / acrylic acid copolymer, acrylonitrile / butadiene copolymer, ethylene / acrylic acid copolymer, water-soluble emulsion such as colloidal silica and acrylic resin composite particles are used. .

Further, a preservative improving agent may be used in combination for the purpose of further preserving the preservability of the recorded image, as long as the effects of the present invention are not impaired. Specific examples of such storage improvers include 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, 4-benzyloxy-
4 '-(2-methyl-2,3-epoxypropyloxy) diphenyl sulfone, 2,2'-methylenebis (4
-Methyl-6-tert-butylphenol), 4,4'-
Butylidene bis (6-tert-butyl-3-methylphenol), 2,2'-methylenebis (4-ethyl-6-te)
rt-butylphenol), 2,4-di-tert-butyl-
3-methylphenol, 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′-butylidenebis (6-tert-butyl-m-cresol), 2,5-
Di (tert-butyl) hydroquinone, 2,5-di (tert
-Amyl) hydroquinone, 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'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenyl sulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3) , 5-Dichlorophenyl) propane, 2,2-bis (4-hydroxy3.5-dimethylphenyl) propane and other hindered phenol compounds, 1
-[Α-Methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, N, N'-di-2-naphthyl- p-phenylenediamine, 2,2-methylenebis (4,6-di-tert-butylphenyl) sodium phosphate,
Examples thereof include a copolymer of glycidyl methacrylate and styrene, and tris (2,3-epoxypropyl) isocyanurate.

If desired, various auxiliary agents can be added to the coating solution. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, lauryl alcohol sulfate / sodium salt, and fatty acid metal salt. , UV absorbers, other defoaming agents, fluorescent dyes, coloring dyes, etc. are appropriately added.

Specific examples of the ultraviolet absorber include, for example, phenyl salicylate, p-tert-butylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxynzophenone, 2-hydroxy-4-octylbenzophenone. , 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2-
(2'-Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2-
(2'-hydroxy-5'-tert-octylphenyl)
Benzotriazole, 2- (2'-hydroxy-3 ',
5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-
Amylphenyl) benzotriazole, 2,4-di-te
rt-Butylphenyl-3,5-di-tert-butyl-4-
Hydroxybenzoate, 2- (2'-hydroxy-
5'-tert-butylphenyl) benzotriazole, 2
-(2'-hydroxy-3 ', 5'-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2H-
Benzotriazol-2-yl) -4-methyl-6-dodecylphenol, bis [2-hydroxy-3- (2 '
H-yl-benzotriazole) -5-octylphenyl] methane.

Further, if necessary, zinc stearate,
Add waxes such as calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined kaolin, titanium oxide, diatomaceous earth, fine anhydrous silica and activated clay. It is also possible to use a sensitizer together depending on the purpose.

Specific examples of the sensitizer include stearic acid amide, stearic acid methylenebisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide and other fatty acid amides, p-benzylbiphenyl, 1,2-
Di (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 1- (2-methylphenoxy) -2- (4
-Methoxyphenoxy) ethane, naphthylbenzyl ether, benzyl-4-methylthiophenyl ether, oxalic acid dibenzyl ester, oxalic acid-di-p-methyl-benzyl ester, oxalic acid-di-p-chloro-benzyl ester, terephthalic acid Examples thereof include dimethyl ester, terephthalic acid dibutyl ester, terephthalic acid dibenzyl ester, isophthalic acid dibutyl ester, 1-hydroxynaphthoic acid phenyl ester, benzyl-4-methylthiophenyl ether and various known heat-fusible substances.

Among these sensitizers, 1,2-di (3-methylphenoxy) ethane and oxalic acid-di-p-methylbenzyl ester are preferably used in the thermosensitive recording medium of the present invention. Further, it is generally desirable to adjust the amount of the sensitizer to be used in the range of about 400 parts by weight or less with respect to 100 parts by weight of the color developing agent.

The method of forming the recording layer is not particularly limited, and the heat-sensitive recording layer forming coating liquid is applied to the support by a suitable coating method such as air knife coating, varibar blade coating, pure blade coating, short dwell coating. It is formed by a method such as drying. The coating amount of the coating liquid is not particularly limited, 1 to 15 g / m ² is usually dry weight, preferably from 2 to 10 g / m ²
Adjusted in a range of degrees.

In the heat-sensitive recording material of the present invention, by providing a protective layer on the heat-sensitive recording layer, it is possible to further improve the light resistance of the recording / printing portion and the suppression of discoloration of the background portion. When the above ultraviolet absorber is added to the protective layer, the amount is preferably 1 to 25% by weight based on the total solid content of the protective layer.

Further, the above-mentioned epoxy compound may be added to the protective layer in order to improve the preservability of recording and printing. The above-mentioned epoxy compound is preferably in the range of 0.5 to 50% by weight based on the total solid amount of the protective layer.

The protective layer is generally formed by using a water-soluble or water-dispersible polymer as a main component, and specific examples of such a polymer include various binders as described above. Among these, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol are particularly preferably used because they have excellent effects as a protective layer.

In order to further improve the water resistance of the protective layer, glyoxal, formalin, glycine, glycidyl ester, glycidyl ether, dimethylol urea,
Ketene dimer, dialdehyde starch, melamine resin, polyamide resin, polyamide-epichlorohydrin resin,
A curing agent such as a ketone-aldehyde resin, borax, boric acid, ammonium zirconium carbonate, or an epoxy compound may be used in combination.

Further, in the protective layer, for improving the printability and sticking, for example, 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 Formalin resin filler, organic pigments such as raw starch particles, and the like can be blended as necessary. In addition, it is desirable that the amount of such a pigment is adjusted within a range of about 5 to 500 parts by weight with respect to 100 parts by weight of the binders.

In the coating liquid for forming the protective layer, if necessary, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax, and surfactants such as sodium dioctylsulfosuccinate ( Various auxiliaries such as a dispersant, a lubricant) and an antifoaming agent can be added as appropriate.

The protective layer coating liquid thus prepared is coated on the thermosensitive recording layer by a suitable coating device. If the coating amount is 20 g / m ² on a dry weight basis, the recording sensitivity of the thermosensitive recording material is lowered. Generally, 0.1-20 g /
It is desirable to adjust in the range of about m ² , preferably 0.5 to 10 g / m ² .

If necessary, a protective layer may be provided on the back side of the thermosensitive recording medium to further improve the storability. Furthermore, providing an undercoat layer on the support,
If necessary, various publicly known techniques in the field of heat-sensitive recording material production can be added, such as processing the back surface of the recording material with an adhesive to process it into an adhesive label. As a support,
Paper, plastic film, synthetic paper, etc. are used,
Paper is most preferably used in terms of price, coating suitability and the like.

[0031]

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.

Example 1 Formation of Undercoat 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 undercoat layer. The obtained coating solution was applied to a high-quality paper of 70 g / m ² and the coating amount after drying was 7 g
The undercoat layer was formed by applying and drying so that the undercoat layer had a thickness of / m ² .

Preparation of Solution A 3-di (n-butyl) amino-6-methyl-7-anilinofluorane 20 parts, 1,2-bis (3-methylphenoxy) ethane 40 parts, 5% aqueous solution of methylcellulose 2
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 A composition consisting of 40 parts of 4,4′-isopropylidenediphenol, 20 parts of a 5% aqueous solution of methylcellulose, and 10 parts of water was pulverized by a sand mill until the average particle size became 1.2 μm.

Preparation of Liquid C 5 parts of 3,7-bis (dimethylamino) -10-benzoylphenothiazine, 5% aqueous solution of methylcellulose 3
Parts and 2 parts of water were pulverized with a sand mill until the average particle size became 2.0 μm.

Preparation of Solution D 2-tert-butyl-6- (3'-tert-butyl-2-hi
Droxy-5-methylbenzyl) -4-methylphenyl
10 parts of acrylate, 5% aqueous solution of methylcellulose 5
Part and 15 parts of water on a sand mill
It was pulverized until the particle diameter became 1.5 μm. Formation of Recording Layer 130 parts of A solution, 70 parts of B solution, 10 parts of C solution, 30 parts of D solution,
200 parts of 10% polyvinyl alcohol aqueous solution, light carbonic acid
Calcium 50 parts, fine particle silicon oxide 20 parts, stearin
Mix 10 parts of 30% zinc oxide dispersion and 100 parts of water
The mixture was stirred to obtain a coating liquid for thermosensitive recording layer. The coating liquid obtained above
Dry weight of undercoat layer is 3g / m ²So that
After coating / drying, heat-sensitive recording material with super calendar processing
Got

Example 2 In preparation of solution D, 2-tert-butyl-6- (3'-te
rt-butyl-2-hydroxy-5-methylbenzyl)
2- [1 instead of -4-methylphenyl acrylate
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that-(2-hydroxy-3,5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenylacrylate was used.

Example 3 In preparation of solution A, 3-di (n-butyl) amino-6-
Instead of methyl-7-anilinofluorane, 3- (N-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane was used.

Example 4 In the same manner as in Example 1 except that 4,4'-bis (Np-tolylsulfonylurea) diphenylmethane was used in place of 4,4'-isopropylidenediphenol in the preparation of solution B. A thermosensitive recording medium was obtained.

Example 5 On the heat-sensitive recording layer obtained in Example 1, 80 parts of a 10% aqueous solution of acetoacetylated polyvinyl alcohol, partially saponified polyvinyl alcohol (trade name; PVA-217,
20% 10% aqueous solution of Kuraray Co., Ltd., 20 parts kaolin,
A coating solution obtained by mixing 2 parts of a 10% aqueous solution of glyoxal and 50 parts of water with stirring was applied and dried so that the coating amount after drying was 1 g / m ² to obtain a thermosensitive recording material having a protective layer. It was

Example 6 In the preparation of solution C, 3,7-bis (dimethylamino)-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 3,7-bis (di-n-butylamino) -10- (4-chlorobenzoyl) phenothiazine was used instead of 10-benzoylphenothiazine.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the liquid C was not used in forming the recording layer of Example 1.

Comparative Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the D liquid was not used in the formation of the recording layer of Example 1.

Comparative Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 4 except that the liquid C was not used in forming the protective layer of Example 5.

Comparative Example 4 A thermosensitive recording medium was obtained in the same manner as in Example 4 except that the D liquid was not used in forming the protective layer of Example 5.

The heat-sensitive recording material thus obtained was subjected to the following evaluation tests and the results are shown in Table 1. [Color density] Thermal recording material evaluation machine (trade name: THPMD,
Okura Electric Co., Ltd.) applied energy 0.2 mJ / do
Recording was performed at t, and the color density of the obtained recorded image was measured by a Macbeth densitometer (RD-914 type, manufactured by Macbeth Co.) visual mode. [Whiteness] Spectral reflectance meter (Product name: ELREPHO20
00) Measured with _R457 .

[Environmental test] A weather meter (product name: SUNSH) in which a thermosensitive recording medium is set under the conditions of light source xenon, 63 ° C. and 50% RH.
INE XENON LONG LIFE WEATH
After leaving it in ER METER, manufactured by Suga Test Instruments Co., Ltd. for 8 hours, the background part is subjected to a spectral reflectometer (ELREPHO200).
0), the whiteness was measured with R _457, the recording unit by measuring at Macbeth reflection densitometer to measure the photostability.

After being left for 100 hours with a fluorescent lamp of 5000 Lux, the whiteness of the background portion and the storage stability of the recording portion were measured under the conditions as described above.

[0049]

[Table 1]

[0050]

As is clear from the results shown in Table 1, the thermosensitive recording medium of the present invention has little background discoloration due to photooxidation and is excellent in light stability of a recorded image.

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[Procedure amendment]

[Submission date] October 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

As a coloring agent used in combination with a leuco dye
Are various known inorganic or organic acidic substances, examples
For example, activated clay, attapulgite, colloidal silica,
Inorganic acidic substances such as aluminum silicate, 4,4'-sec-
Butylidene diphenol, 4-phenylphenol,
4,4'-isopropylidenediphenol, 4,4'-
Dihydroxydiphenyl-2,2-butane, 2,4'-
Hydroxydiphenyl sulfone, 4,4'-hydroxy
Diphenyl sulfone, 4-hydroxy-4'-isopro
Pyroxydiphenyl sulfone, bis (3-allyl-4)
-Hydroxyphenyl) sulfone, 4-hydroxy-
4'-methyldiphenyl sulfone, 3,4-hydroxy
Diphenyl sulfone, 3,4-dihydroxy-4'-me
Tylphenyl sulfone, 4,4'-dihydroxy diphe
Nylmethane, 4,4'-cyclohexylidene dipheno
4,4'-dihydroxydiphenyl sulfide,
Hydroquinone monobenzyl ether, 4-hydroxy ester
Nzophenone, 2,4-dihydroxybenzophenone,
Phenyl 4-hydroxybenzoate, 4-hydroxybenzoate
Benzyl fragrance, novolac type phenolic resin, phenol
Phenolic compounds such as polymer, 3-cyclohexyl
-4-hydroxybenzoic acid, 3-benzylsalicylic acid,
3- (α-methylbenzyl) salicylic acid, 3-chloro-
5- (α-methylbenzyl) salicylic acid, 3,5-di-
tert-Butylsalicylic acid, 3-phenyl-5- (α, α
-Dimethylbenzyl) salicylic acid, 3,5-di-α-me
Cylbenzyl salicylic acid, 4- [3- (p-tolylsul
Aromatic carbo such as phenyl) propyloxy] salicylic acid
Zinc salt of acid, 4,4-bis (Np-tolylsulfonyl)
Rare) Organic acidic substances such as diphenylmethane. Leuco dyeing
The ratio of the colorant and colorant used depends on the type of colorant used.
It is appropriately selected and is not particularly limited.
However, in general, a coloring agent of 50 to 50 is added to 100 parts by weight of the dye.
Coloring of 0 parts by weight, preferably about 100 to 300 parts by weight
Agents are used. The coating liquid for the heat-sensitive recording layer is generally prepared by using water as a dispersion medium and dispersing with a stirring / pulverizing machine such as a ball mill or a sand mill.

Claims (2)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a black color-forming leuco dye and a color-developing agent provided on the support.
In the heat-sensitive recording layer, the phenothiazine derivative represented by the following general formula (1) and the following general formula (2) as an antioxidant are used.
A heat-sensitive recording material containing a compound represented by: [Chemical 1] [In the general formula (1), R _{1 to} R ₄ are each C ₁ to
A C ₄ alkyl group is shown, and R ₅ is a hydrogen atom, a halogen atom, a C ₁ -C ₄ alkyl group or a C ₁ -C ₄ alkoxyl group. ] [Chemical 2] [In the general formula (1), R ₁ represents a hydrogen atom or a methyl group. R ₂ represents a tert-butyl group or a tert-amyl group. R ₃ represents a methyl group or a tert-amyl group. ] 2. The heat-sensitive recording material according to claim 1, wherein the phenothiazine derivative is 3,7-bis (dimethylamino) -10-benzoylphenothiazine.