JP2001080219A - Thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording medium which is excellent in the preservability of a recording part against chemicals such as plasticizers and oils and the preservability of a recording part over time, and is excellent in background fog resistance and recording running property. To provide. SOLUTION: In a heat-sensitive recording medium having a heat-sensitive recording layer containing a leuco dye, a color developer and an adhesive on a support, as one means for solving the above-mentioned problems, the present invention relates to 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether is used as an agent, and a graft copolymer of starch and polyvinyl acetate is used as an adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium utilizing a color development reaction between a leuco dye and a color developer.

[0002]

2. Description of the Related Art A thermosensitive recording medium utilizing a color development reaction between a leuco dye and a color developer by heat is relatively inexpensive, the recording equipment is compact, and its maintenance is easy. It is used in media and other broad areas.

[0003] With the expansion of the field of use, there has been a demand for a heat-sensitive recording material which is excellent in the preservability of compounds such as plasticizers, edible oils, and cosmetics in a recording area by a color-forming reaction between a leuco dye and a developer. ing.

A heat-sensitive recording material using 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether as a color developer in order to enhance the plasticizer resistance and oil resistance of the recording portion is a special feature. JP-A-8-333329,
It is described in JP-A-10-29969 and the like, and further disclosed in JP-A-10-297089 and JP-A-10-29.
Japanese Patent No. 7092 discloses a heat-sensitive recording material containing 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether and a diphenylsulfone derivative. There is a demand for improvements.

Japanese Patent Application Laid-Open No. 4-2783 discloses that a thermosensitive recording material using a graft copolymer of starch and polyvinyl acetate as an adhesive has an excellent effect on recording running properties.
Although described in Japanese Patent Publication No. 85, there is a problem that the density of the recording portion tends to decrease with time.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an excellent storage property of a recording section against chemicals such as plasticizers and oils, and excellent preservation property of the recording section over time. An object of the present invention is to provide an excellent thermal recording medium.

[0007]

Means for Solving the Problems In a heat-sensitive recording medium having a heat-sensitive recording layer containing a leuco dye, a color developer and an adhesive on a support, one of the means for solving the above-mentioned problems is as follows. The present invention uses 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether as a color developer and uses a graft copolymer of starch and polyvinyl acetate as an adhesive. . As another means, 4-hydroxy-4′-isopropoxydiphenyl sulfone, 2,2
4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, bis (3-allyl-4
By using at least one selected from -hydroxyphenyl) sulfone and 2,4-bis (phenylsulfonyl) phenol, the effect of improving the recording sensitivity and the storage stability of the recording portion over time can be obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a thermosensitive recording layer,
It contains a specific developer (a) of 2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether and a specific adhesive of a graft copolymer of starch and polyvinyl acetate. The amount of the specific developer and the specific adhesive is not particularly limited, but the specific developer (A) is about 1 to 50% by weight, preferably 1 to 50% by weight, based on the heat-sensitive recording layer. About 30% by weight. The specific adhesive is about 5 to 35% by weight based on the heat-sensitive recording layer.

Further, 4-hydroxy-4 'is used as a developer.
-Selected from isopropoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 2,4-bis (phenylsulfonyl) phenol By using at least one specific developer (b), the effect of improving the recording sensitivity and the storage stability of the recording portion over time can be obtained. Among them, among specific developers (b), 4-hydroxy-
4'-isopropoxydiphenyl sulfone is preferable because of its excellent recording density.

A specific developer (a) and a specific developer (b)
Is not particularly limited, but the specific developer (a) is 5-90 to the total amount of the specific developer (b).
It is preferable to have about 5% by weight, especially about 5 to 50% by weight.

The specific adhesive contained in the heat-sensitive recording layer is
For example, polyvinyl acetate can be directly grafted on a starch mainly composed of amylose and amylopectin obtained from corn, potato, sweet potato, etc. It is obtained by kraft polymerization of the monomer.

The graft ratio of polyvinyl acetate to starch is about 0.5 to 10% by weight. Part of the polyvinyl acetate part in the specific adhesive may be saponified.

Various known leuco dyes can be used in the heat-sensitive recording layer. Specific examples of such leuco dyes include the following. 3,
3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl)
-6-dimethylaminophthalide, 3-diethylamino-
Blue-coloring dyes such as 7-dibenzylamino-benzo [a] fluoran, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluoran, 3-diethylamino-7-aniline Green chromogenic dyes such as linofluoran and 3-diethylamino-7-dibenzylaminofluoran;
3-cyclohexylamino-6-chlorofluoran, 3
Red-coloring dyes such as -diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7-chlorofluoran, rhodamine (o-chloroanilino) lactam, 3-diethylamino-6,8-dimethylfluoran, -(N-ethyl-N-isoamyl) amino-6-
Methyl-7-anilinofluoran, 3- (N-methyl-
N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-
Anilinofluoran, 3-di (n-butyl) amino-6
-Methyl-7-anilinofluoran, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluoran, 3- (N-ethyl-p-toluidino) -6-methyl-7-ani Linofluoran, 3- (N-ethyl-N
-Tetrahydrofurfurylamino) -6-methyl-7-
Anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran and the like Black coloring dye of 3,
3-bis [1- (4-methoxyphenyl) -1- (4-
Dimethylaminophenyl) 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-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-
Dyes having an absorption wavelength in the near infrared region, such as (6'-dimethylamino) phthalide, are not limited thereto, and two or more dyes can be used in combination.

The present invention relates to a specific developer (a) or 2, (2) -bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether as a color developer. And 4-hydroxy-4'-isopropoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 2,4-bis ( (Phenylsulfonyl) phenol and at least one specific developer (b), but other various known developers may be used in combination as long as the desired effects of the present invention are not impaired. You can do it.

As such a developer, for example, 4,4'-
Isopropylidene diphenol, 4,4′-cyclohexylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, benzyl 4-hydroxybenzoate, 1,1-bis (4-hydroxyphenyl) Phenolic compounds such as -1-phenylethane, N
-(P-tolylsulfonyl) carbamoyl acid-p-cumylphenyl ester, N- (o-tolyl) -p-tolylsulfonamide, 4,4′-bis (Np-tolylsulfonylaminocarbonylamino) diphenylmethane Such as those having a —SO ₂ NH— bond in the molecule, such as 4- [2- (p
Of aromatic carboxylic acids such as -methoxyphenoxy) ethyloxy] zinc salicylate, 4- [3- (p-tolylsulfonyl) propyloxy] zinc salicylate, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid Zinc salts and the like.

The use ratio of the leuco dye to the specific developer (a) or the specific developer (a) and the specific developer (b) is not particularly limited, but the weight ratio is not limited. 1: 8
~ 2: 1 is preferred.

Further, the heat-sensitive recording layer may contain various sensitizers for improving the recording sensitivity and a storability improving agent for further improving the storability of the recording portion. Such sensitizers include, for example, stearic acid amide, methylenebisstearic acid amide, dibenzyl terephthalate,
-Benzyl benzyloxybenzoate, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, p-tolylbiphenyl ether, di (4-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- (3-methylphenoxy) ethane, p-
Methylthiophenyl benzyl ether, di (β-biphenylethoxy) benzene, di-p-chlorobenzyl oxalate, di-p-methylbenzyl oxalate, dibenzyl oxalate, and the like.

Examples of such a preservability improver include, for example, 2,
2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-thiobis (2-methyl-6-te
rt-butylphenol), 4-4′-butylidenebis (6-tert-butyl-m-cresol), 1,1,1
3-tris (2-methyl-4-hydroxy-5-tert-
Butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl)
Hindered phenol compounds such as butane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane; 4,4 ′ -Diglycidyloxydiphenyl sulfone, 4-benzyloxy-4 '-(2-
Examples include epoxy compounds such as methyl glycidyloxy) diphenyl sulfone, diglycidyl terephthalate, cresol novolak type epoxy resin, phenol novolak type epoxy resin, and bisphenol A type epoxy resin. The amount of these preservatives to be used is not particularly limited, but it is generally desirable to adjust the amount to 4 parts by weight or less based on 1 part by weight of the leuco dye.

The heat-sensitive recording layer generally uses water as a dispersion medium,
Leuco dye, specific developer, if necessary, preservative improver,
A sensitizer prepared by adding a specific adhesive together or separately with a specific adhesive after finely dispersing them together or separately using a stirrer / pulverizer such as a ball mill, attritor, or sand mill so that the average particle size becomes 2 μm or less. The coating liquid for a recording layer is formed by coating and drying on a support such as high-quality paper (neutral paper or acidic paper), synthetic paper, or transparent film.

Although a specific adhesive is used as the adhesive in the heat-sensitive recording layer, other adhesives may be added to the coating solution for the heat-sensitive recording layer as long as the desired effects of the present invention are not impaired. You can also. The total amount of the adhesive used is about 5 to 35% by weight based on the heat-sensitive recording layer.

Examples of such other adhesives include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, starch oxide, casein, styrene-maleic anhydride copolymer, methyl vinyl ether-
Water-soluble resins such as maleic anhydride copolymer and isopropylene-maleic anhydride copolymer, and water-dispersible resins such as styrene-butadiene latex, acrylic latex and urethane latex are exemplified.

Further, various auxiliaries can be added to the heat-sensitive recording layer coating liquid as needed, for example, kaolin,
Light (heavy) calcium carbonate, calcined kaolin, titanium oxide, magnesium carbonate, aluminum hydroxide, amorphous silica, pigments such as urea / formalin resin filler, sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, lauryl alcohol sulfate Sodium, surfactants such as fatty acid metal salts, zinc stearate, calcium stearate, waxes such as polyethylene wax, carnauba wax, paraffin wax, ester wax, glyoxal, urea formalin resin, polyamide epoxy resin, polyamide epichlorohydrin, adipic dihydrazide , Boric acid, borax, ammonium zirconium carbonate and the like, as well as UV absorbers, defoamers, fluorescent dyes, coloring dyes and the like.

A protective layer may be provided on the heat-sensitive recording layer in order to increase the chemical resistance and water resistance of the recording portion or to improve the recording running property. Such a protective layer is formed, for example, by applying a coating liquid for a protective layer containing a film-forming adhesive and, if necessary, a pigment as a main component on the heat-sensitive recording layer and drying.

The adhesive contained in the coating liquid for the protective layer includes completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol. Polyvinyl alcohols, starches, etc.
Hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, diisobutylene / maleic anhydride copolymer salt,
Styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt,
Styrene / butadiene latex, acrylic latex, urethane latex, and the like can be given.

In the coating solution for the protective layer, an auxiliary agent which can be added to the coating solution for the heat-sensitive recording layer may be added. The coating amount of the heat-sensitive recording layer coating liquid is 2 to 12 g / dry weight.
m ^2, preferably from 3 to 7 g / m ² approximately, the coating amount of the protective layer coating composition is 0.5 to 10 g / m ² by dry weight, preferably 1
５5 g / m ² .

Further, in order to enhance the recording sensitivity and recording image quality, an undercoat layer containing an oil-absorbing pigment or hollow particles as a main component is provided between the support and the heat-sensitive recording layer. It is also possible to apply a chemical treatment. Various other known techniques in the field of heat-sensitive recording medium production can be added as needed.

[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. In the examples, [parts] and [%] indicate [parts by weight] and [% by weight], respectively, unless otherwise specified.

Example 1 Preparation of Coating Liquid for Undercoat Layer 70 parts of calcined clay (trade name: Ansilex, manufactured by Engel Hard Co., oil absorption 110 ml / 100 g), plastic pigment (trade name: Grosdale 104S, solid content) : 46%, manufactured by Mitsui Chemicals, Inc., 38 parts, starch-polyvinyl acetate graft copolymer (trade name: Petrocoat C)
-8, 33 parts of a 12% aqueous solution of Nisse Chemical Co., Ltd., 2 parts of carboxymethyl cellulose (trade name: Cellogen 7A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), styrene-butadiene latex (trade name: L-1537Y, solid content) : 50%, manufactured by Asahi Kasei Kogyo Co., Ltd.) and 14 parts of water and 100 parts of water were mixed and stirred by a high-speed stirrer to obtain a coating liquid for an undercoat layer.

Preparation of solution A 16 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 8 parts of a 10% aqueous solution of polyvinyl alcohol (degree of saponification 65 mol%, degree of polymerization 200) , And 26 parts of water were pulverized with a sand grinder until the average particle diameter became 0.8 μm to obtain a liquid A.

Preparation of solution B 20 parts of 4-hydroxy-4'-isopropoxydiphenylsulfone, 15 parts of di-p-methylbenzyl oxalate, polyvinyl alcohol (degree of saponification 65 mol%,
A composition composed of 20 parts of a 10% aqueous solution having a degree of polymerization of 200) and 45 parts of water was subjected to a sand grinder to give an average particle size of 1.
The solution B was obtained by pulverizing until the particle size became 0 μm or less.

Preparation of Solution C A color developer containing about 55% by weight of 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether (trade name: D-90, manufactured by Nippon Soda Co., Ltd.) 20
Parts, 15 parts of oxalic acid di-p-methylbenzyl ester,
Polyvinyl alcohol (degree of saponification 65 mol%, degree of polymerization 2
A composition comprising 20 parts of a 10% aqueous solution of (00) and 45 parts of water was pulverized with a sand grinder until the average particle diameter became 1.0 μm or less, to obtain a liquid C.

Preparation of coating solution for heat-sensitive recording layer 25 parts of solution A, 75 parts of solution B, 25 parts of solution C, 12 parts of calcium carbonate (trade name: Brilliant 15, manufactured by Shiraishi Calcium Co., Ltd.), aluminum hydroxide (trade name) : Heidilite H-42, manufactured by Showa Denko KK) 10 parts, zinc stearate 30% dispersion liquid 25 parts, paraffin wax 30% dispersion liquid 15 parts, starch-vinyl acetate graft copolymer 20
80% aqueous solution (trade name: Petrocoat C-8, manufactured by Nisse Chemical Co., Ltd.), polyvinyl alcohol (trade name: PVA-
110, manufactured by Kuraray Co., Ltd.) and a composition comprising 38 parts of a 12% aqueous solution and 30 parts of water were stirred and mixed to obtain a thermosensitive recording layer coating liquid.

Preparation of thermosensitive recording medium 8.0 g of an undercoat layer coating solution after drying with a pure blade coater on acidic woodfree paper having a basis weight of 50 g / m ^2.
/ M ² after application and drying, supercalendering to form an undercoat layer, and then applying a coating solution for the heat-sensitive recording layer thereon with a rod blade coater so that the applied amount after drying is 5 g / m ^2. After drying, using a super calender, Oken type smoothness (JAPAN TAPPI No. 5) was 150.
A smoothing treatment was performed so that the time became 0 second to obtain a thermosensitive recording medium.

Example 2 In the preparation of Solution B of Example 1, 4-hydroxy-4'-
2,4 'instead of isopropoxydiphenyl sulfone
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that -dihydroxydiphenylsulfone was used.

Example 3 In the preparation of solution B in Example 1, 4-hydroxy-4'-
4,4 'instead of isopropoxydiphenyl sulfone
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that -dihydroxydiphenylsulfone was used.

Example 4 In the preparation of Solution B of Example 1, 4-hydroxy-4'-
Bis (3) instead of isopropoxydiphenyl sulfone
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that (allyl-4-hydroxyphenyl) sulfone was used.

Example 5 In the preparation of Solution B of Example 1, 4-hydroxy-4'-
2,4- instead of isopropoxydiphenyl sulfone
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that bis (phenylsulfonyl) phenol was used.

Example 6 The procedure of Example 1 was repeated, except that 90 parts of solution B and 10 parts of solution C were used instead of 75 parts of solution B and 25 parts of solution C in the production of the thermosensitive recording medium of example 1. Thus, a thermosensitive recording medium was obtained.

Example 7 The procedure of Example 1 was repeated, except that 50 parts of B liquid and 50 parts of C liquid were used instead of 75 parts of B liquid and 25 parts of C liquid in the production of the thermosensitive recording medium of Example 1. Thus, a thermosensitive recording medium was obtained.

Example 8 In the production of the thermosensitive recording medium of Example 1, except that 100 parts of liquid C was used instead of 75 parts of liquid B and 25 parts of liquid C,
A thermosensitive recording medium was obtained in the same manner as in Example 1.

Example 9 In the preparation of the coating solution for the heat-sensitive recording layer of Example 1, 80 parts of a 20% aqueous solution of starch-vinyl acetate graft copolymer (trade name: Petrocoat C-8, manufactured by Nissei Chemical Co., Ltd.) And 20 parts of a 20% aqueous solution of the starch-vinyl acetate graft copolymer and 138 parts of a 12% aqueous solution of the polyvinyl alcohol were used instead of 38 parts of a 12% aqueous solution of polyvinyl alcohol (trade name: PVA-110, manufactured by Kuraray Co., Ltd.) A heat-sensitive recording material was obtained in the same manner as in Example 1 except for using the same.

Comparative Example 1 In the preparation of the coating solution for the heat-sensitive recording layer of Example 1,
20% aqueous solution of vinyl acetate graft copolymer (trade name:
Example 1 except that 80 parts of a 20% aqueous solution of oxidized starch (trade name: Ace C, manufactured by Oji Cornstarch) was used instead of 80 parts of Petrocoat C-8 (manufactured by Nichien Chemical Co., Ltd.).
In the same manner as in the above, a thermosensitive recording medium was obtained.

Comparative Example 2 In the preparation of the coating solution for the heat-sensitive recording layer of Example 1,
20% aqueous solution of vinyl acetate graft copolymer (trade name:
A thermosensitive recording medium was obtained in the same manner as in Example 1, except that 40 parts of a vinyl acetate-based latex (solid concentration: 40%) was used instead of 80 parts of Petrocoat C-8 (manufactured by Nisse Chemical Corporation).

Comparative Example 3 In the preparation of the coating solution for the heat-sensitive recording layer of Example 1,
20% aqueous solution of vinyl acetate graft copolymer (trade name:
Instead of 80 parts of Petrocoat C-8, manufactured by Nisse Chemical Co., Ltd., polyvinyl alcohol (trade name: PVA-110,
Except that 133 parts of a 12% aqueous solution of Kuraray Co., Ltd.) was used.
A thermosensitive recording medium was obtained in the same manner as in Example 1.

The thus-obtained thermosensitive recording medium was subjected to the following evaluation tests, and the results are shown in Table 1.

[Background Fog Resistance] The background fog resistance of the heat-sensitive recording medium after standing at 40 ° C. and 90% RH for 24 hours was measured for whiteness using a Hunter whiteness meter. The larger the value, the more excellent the background fog resistance.

[Recording Density and Recording Runnability] Using a thermosensitive recording medium evaluation machine (trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.), recording was performed at an applied energy of 0.3 mj / dot.
The density of the recording portion was measured in a visual mode using a Macbeth densitometer (RD-914, manufactured by Macbeth), and the recording running property was determined as follows from the degree of sticking or thermal head residue generated during recording. ：: Sticking and thermal head residue hardly occurred. ：: Sticking or thermal head residue was slightly generated. X: Sticking or a large amount of thermal head residue was generated.

[Temporary Storage Property of Recording Section] The density of the recording section after the thermal recording medium recorded in the above evaluation of the recording density was allowed to stand at 30 ° C. and 80% RH for 7 days was measured using a Macbeth densitometer (R).
D-914, manufactured by Macbeth) in the visual mode.

[Plasticizer resistance] Polypropylene pipe (4
A vinyl chloride wrap film (manufactured by Nippon Carbide Industrial Co., Ltd.) is wound three times on a 0 mmφ tube, and the thermosensitive recording medium recorded in the above-described evaluation of the recording density is sandwiched therebetween so that the recording surface is outside. A vinyl chloride wrap film was wound three times from above, and after standing at 25 ° C. for 24 hours, the density of the recording portion was measured with a Macbeth densitometer (RD-914, manufactured by Macbeth) in visual mode.

[Oil resistance] One drop of salad oil is dripped on the recording portion of the heat-sensitive recording medium recorded in the above evaluation of the recording density.
After one minute, wipe off excess oil with tissue paper,
The density of the recording portion was measured in a visual mode using a Macbeth densitometer (RD-914, manufactured by Macbeth).

[0051]

[Table 1]

[0052]

The heat-sensitive recording material of the present invention is excellent in the preservability of the recording portion against chemicals such as plasticizers and oils and the preservability of the recording portion over time, and also has excellent background fog resistance and recording running performance. It has an effect.

Continued on the front page (72) Inventor: Takashi Takemura 1850, Oudotaka, Nichinan-shi, Miyazaki Prefecture Oji Paper Co., Ltd. Nichinan Mill F-term (reference) 2H026 AA07 BB02 BB25 BB30 CC01 CC05 FF01 4H056 BB05 BB14 BC01 BD01 BE06 BF02F BF26F BF28E FA03

Claims (3)

[Claims] 1. A thermosensitive recording medium having a thermosensitive recording layer containing a leuco dye, a developer and an adhesive on a support, wherein the developer is 2,2′-bis [4- (4-hydroxyphenyl). (Sulfonyl) phenoxy] diethyl ether, and the adhesive is a graft copolymer of starch and polyvinyl acetate. 2. The heat-sensitive recording layer further comprises 4-
Hydroxy-4'-isopropoxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 4,
The heat-sensitive recording material according to claim 1, further comprising at least one selected from 4'-dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, and 2,4-bis (phenylsulfonyl) phenol. 3. The method according to claim 2, wherein the 2,2′-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether is 4-hydroxy-4′-isopropoxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 3. The heat-sensitive recording according to claim 2, wherein the thermosensitive recording medium has 5 to 90% by weight based on the total amount of 4'-dihydroxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone and 2,4-bis (phenylsulfonyl) phenol. body.