JP2000255168A - Adhesive sheet for heat sensitive recording and method for using the sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive sheet for sensitive recording, which is prominent in the heat resistant preservation property of a skin unit and the preservation stability of a recording unit against chemicals, such as plasticizer, edible oil and the like, and the method for using the sheet. SOLUTION: In an adhesive sheet for heat sensitive recording, having a heat sensitive recording layer containing leuco dye and color developing agent, and a protecting layer sequentially on one side of a substrate and an adhesive agent layer, containing an adhesive agent as the principal, constituent of the same and provided on the other side of the substrate 2,2'-bis[4-(4-hydroxy phenyl sulfonyl)phenoxy diethyl ether] and 2,2'-bis[4-[4-(4-hydroxy phenyl sulfonyl) phenoxy-2-ethylene oxyethoxy]phenyl sulfonyl]phenoxy]diethyl ether or the like, which is shown by a formula, is contained in the heat sensitive recording layer as the color developing agent as a means for obtaining the adhesive sheet for the heat sensitive recording. In the formula, n shows an integer of 1-3.

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 pressure-sensitive adhesive sheet utilizing a color-forming reaction between a leuco dye and a color former, and more particularly to a heat-sensitive recording sheet which is excellent in heat resistance storage stability of a background portion and storage stability of a printed image. And a method for using the same.

[0002]

2. Description of the Related Art A pressure-sensitive adhesive sheet for heat-sensitive recording in which a plurality of color-forming substances are brought into contact by heat to obtain a recorded image is well known. As described above, the heat-sensitive recording pressure-sensitive adhesive sheet is relatively inexpensive, the recording device is compact, and the maintenance thereof is easy. Therefore, the pressure-sensitive adhesive sheet is used in recording media such as facsimile machines and various computers, and in a wide variety of fields.

[0003] As one of the fields of use, for example, POS
(Point of sales) Thermal recording pressure-sensitive adhesive sheets for systems. In recent convenience stores, systems for selling food after cooking it in a microwave oven have been introduced, and the heat-sensitive adhesive sheet for heat-sensitive recording, that is, the heat-sensitive adhesive label for heat-sensitive recording, which is attached to the packaging material of those foods, The entire surface is colored by hot water (steam) generated during cooking, and there is a problem that a bar code cannot be read at a cash register after cooking. Further, if the water resistance is insufficient, the printed portion is decolored by hot water (water vapor), or the recording portion is peeled off and cannot be used. On the other hand, in the case of frozen foods, since a heat-sensitive recording pressure-sensitive adhesive sheet is stuck on or under the wrapped product, the water resistance, plasticizer resistance, and water-resistant plasticizer resistance of the recording portion are also required. I have.

A heat-sensitive recording material using 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether as a colorant in order to enhance the plasticizer resistance and oil resistance of the recording portion is disclosed in Japanese Patent Application Laid-Open No. Hei 8 (1994) -108. -333329 and JP-A-10-29969.
Japanese Patent No. 29969 describes that the compound represented by the general formula (1) is used as a colorant, but a pressure-sensitive adhesive sheet for heat-sensitive recording which is excellent in hot water resistance (microwave resistance) is also disclosed. Requested.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording pressure-sensitive adhesive sheet which is excellent in heat-resistant storage stability of the background portion, storage stability against chemicals such as plasticizers and edible oils in the recording portion, and water-resistant plasticizer resistance. And a method of using the same.

[0006]

Means for Solving the Problems A heat-sensitive recording layer containing a leuco dye and a coloring agent and a protective layer are sequentially provided on one surface of a support, and an adhesive is mainly provided on the other surface of the support. The present invention relates to a heat-sensitive recording pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer contained as a component, as one means for obtaining the heat-sensitive recording pressure-sensitive adhesive sheet of the above-mentioned problem. , 2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether and a compound represented by the following general formula (1).

[0007]

Embedded image (In the general formula (1), n represents an integer of 1 to 3.)

Further, as a method of using such a pressure-sensitive adhesive sheet for heat-sensitive recording, the present invention is used for a label of a food to be heated by a microwave oven.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention comprises
In a heat-sensitive recording pressure-sensitive adhesive sheet having a heat-sensitive recording layer containing a leuco dye and a color former, and a protective layer in order and having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive as a main component on the other surface of the support, The recording layer contains 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether and a compound represented by the above general formula (1) as a coloring agent. Thereby, effects excellent in heat resistance storage stability of the background portion, storage stability against chemicals such as plasticizers and edible oils in the recording portion, and waterproof plasticizer resistance can be obtained.

The heat-sensitive recording pressure-sensitive adhesive sheet having such a structure can be used as a label for foods to be heated by a microwave oven, and can be used as a plasticizer in a film wrap or a pressure-sensitive adhesive layer in a film wrapping food. The recording portion is not erased by an adhesive or the like, and has an effect of preventing fogging even if the background portion is heated by a microwave oven.

In particular, the weight ratio of 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by formula (1) is 1: 1 to 1: 1.
By using the recording medium at a ratio of 4: 1, a very excellent effect can be obtained on the storage stability of the recording section over time.

In the heat-sensitive recording layer, 2,2'-
A specific colorant comprising bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether and a compound represented by the general formula (1) is used, provided that the desired effects of the present invention are not impaired. And other colorants may be contained.

As such other colorants, for example,
4'-isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 2,4 '-Dihydroxydiphenyl sulfone, 4,
4′-dihydroxydiphenyl sulfone, 4-hydroxy-4′-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
-Hydroxy-4'-methyldiphenylsulfone, 1,
4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α
Phenolic compounds such as-(4'-hydroxyphenyl) ethyl] benzene, N- (p-toluenesulfonyl)
Carbamoyl acid-p-cumylphenyl ester, Np
-Tolylsulfonyl-N'-p-tolylurea, 4,4 '
- bis (N-p-tolyl-sulfonylamino Cabo sulfonyl amino) having a -SO ₂ NH- bond in the molecule of diphenylmethane, 4- [2-(p-methoxyphenoxy)
Zinc salts of aromatic carboxylic acids such as zinc ethylethyl] salicylate and zinc 4- [3- (p-tolylsulfonyl) propyloxy] salicylate.

As the leuco dye contained in the heat-sensitive recording layer, various known leuco dyes are used. 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-7
Blue-coloring dyes such as -dibenzylamino-benzo [a] fluoran, 3- (N-ethyl-N-p-tolyl) amino-7-N-methylanilinofluoran, 3-diethylamino-7-anilino Fluoran, 3-diethylamino-
Green color-forming dyes such as 7-dibenzylaminofluoran,
-Cyclohexylamino-6-chlorofluoran, 3-
Diethylamino-6-methyl-7-chlorofluoran,
Red-coloring dyes such as 3-diethylamino-7-chlorofluorane, 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-pentyl)
Amino-6-methyl-7-anilinofluoran, 3-diethylamino-7- (o-chlorophenylamino) fluoran, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluoran, 3- (N-ethyl-
p-Toluidino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro- 7-anilinofluoran,
Black coloring dyes such as 3-pyrrolidino-6-methyl-7-anilinofluoran and 3-piperidino-6-methyl-7-anilinofluoran; 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 ′-(6′-dimethylamino)
Dyes having an absorption wavelength in the near infrared region, such as phthalide. Of course, the present invention is not limited to these, and two or more kinds can be used in combination. The amount of the leuco dye used is about 5 to 30% by weight based on the heat-sensitive recording layer.

The ratio of the leuco dye to the specific colorant used is appropriately selected according to the type of the leuco dye used, and is not particularly limited. 1 to 10 parts by weight, preferably about 1 to 5 parts by weight of a specific colorant is used.

The heat-sensitive recording layer may further contain a storability improving agent for increasing the storage stability of the recording portion and a sensitizer for increasing the recording sensitivity. Specific examples of such a preservability improver include, for example, 2,2′-methylenebis (4-methyl-6-tert-butylphenol),
2′-ethylidenebis (4,6-di-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,
3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-thiobis (3-
Methylphenol), 2,2-bis (4-hydroxy-
Hindered phenols such as 3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane Compound,
4,4'-diglycidyloxydiphenyl sulfone, 4
-Benzyloxy-4 '-(2-methylglycidyloxy) diphenylsulfone, diglycidyl terephthalate,
Epoxy compounds such as cresol novolak type epoxy resin, phenol novolak type epoxy resin, bisphenol A type epoxy resin and the like can be mentioned.

Specific examples of the sensitizer include, for example, stearic acid amide, methylenebisstearic acid amide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, 2-naphthyl benzyl ether, m-terphenyl, p-benzylbiphenyl , P-tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1,
2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-
Chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p −
Acetotoluidide, p-acetophenethidide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, dioxalate -P-chlorobenzyl ester, di-p-methylbenzyl oxalate, dibenzyl oxalate and the like. The amounts of these preservatives and sensitizers are not particularly limited, but are generally preferably adjusted to 4 parts by weight or less based on 1 part by weight of leuco.

The heat-sensitive recording layer generally uses water as a dispersion medium,
For example, a leuco dye, a color former, if necessary, a sensitizer, a preservative improver, etc., together or separately, finely dispersed by a stirring / pulverizer such as a ball mill, attritor, sand mill or the like so that the average particle diameter becomes 2 μm or less. After that, a coating solution for a heat-sensitive recording layer prepared by adding an adhesive and, if necessary, an auxiliary agent is applied to a support and dried.

Specific examples of the adhesive added to the coating solution for the heat-sensitive recording layer include starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol,
Acetoacetyl group-modified polyvinyl alcohol, silicon polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, Polyurethane-based latex, styrene-butadiene-based latex and the like can be mentioned. The amount of the adhesive used is about 5 to 30% by weight based on the total solid content of the heat-sensitive recording layer.

The auxiliary agent added to the coating solution for the heat-sensitive recording layer includes, for example, kaolin, light (heavy) calcium carbonate, calcined kaolin, titanium oxide, magnesium carbonate,
Pigments such as aluminum hydroxide, amorphous silica, urea / formalin resin filler, surfactants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, zinc stearate, steer Lubricants such as calcium phosphate, waxes such as polyethylene wax, carnauba wax, paraffin wax, ester wax, glyoxal, urea formalin resin, melamine-formalin resin, methylol urea, compounds having a methylol group such as ketone resin, glycerol polyglycidyl ether, Compounds having an epoxy group such as polyamide epichlorohydrin resin, hydrazine compounds such as adipic dihydrazide, boric acid, borax, ammonium zirconium carbonate Crosslinking agents and the like, and ultraviolet absorbers, antifoaming agents, fluorescent dyes, coloring dyes, mold release agents, antioxidants, and the like.

The protective layer provided to further enhance the chemical resistance of the recording portion or the recording running property may be formed, for example, by applying a protective layer coating liquid containing a film-forming adhesive and, if necessary, a pigment as a main component. It is formed by coating and drying on the layer. Examples of the adhesive contained in the protective layer coating liquid include polyvinyl alcohol such as 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. Alcohols, starches, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt And styrene / acrylic acid copolymer salts, urea resins, melamine resins, amide resins, acrylic resin-based latex, urethane resin-based latex, and the like.

Among them, polyvinyl alcohols, especially modified polyvinyl alcohol which can be easily crosslinked by a water-resistant agent such as carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol and diacetone-modified polyvinyl alcohol, are used in the present invention. This is preferable under severe conditions such as exposure of the sheet to hot water (steam).

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 can be added as long as the desired effect of the present invention is not impaired.

In the present invention, a gloss layer cured by irradiating the ionizing radiation-curable compound with ultraviolet rays or electron beams may be provided on the protective layer. Such a gloss layer is formed by applying a coating liquid for a gloss layer containing an ionizing radiation-curable compound as a main component on a protective layer and then irradiating an ultraviolet ray or an electron beam to polymerize the ionizing radiation-curable compound.

The other surface of the support is provided with an adhesive layer containing an adhesive as a main component. The pressure-sensitive adhesive is not particularly limited, and examples thereof include a natural rubber and an acrylic resin-based pressure-sensitive adhesive, or a styrene isoprene copolymer and a two-part crosslinkable acrylic resin-based re-peelable pressure-sensitive adhesive.

The pressure-sensitive adhesive layer may be formed by applying a hot-melt pressure-sensitive adhesive to the other surface of the support, or by applying a pressure-sensitive adhesive layer coating liquid containing an emulsion-polymerized pressure-sensitive adhesive as a main component. It is formed by a coating method of applying and drying the other surface. In general, when an emulsion-polymerized pressure-sensitive adhesive, particularly an emulsion-polymerized acrylic resin-based pressure-sensitive adhesive, is used, the recording sensitivity of the recording section decreases with time due to the effects of the emulsifier and the monomers and oligomers in the pressure-sensitive adhesive. By using the coloring agent used in the present invention, an effect of remarkably improving such a decrease in the recording density can be obtained.

Incidentally, The heat-sensitive recording sheet of the present invention can be finished into a so-called linerless type in which a release paper is laminated on a pressure-sensitive adhesive layer and a protective layer is provided with a release layer. In particular, as a resin used as a release layer provided on the protective layer, an ultraviolet-curable or electron-beam-curable silicone resin is preferably used because heat curing is not required.

The method for forming the heat-sensitive recording layer and the protective layer is not particularly limited, and includes, for example, air knife coating, variver blade coating, pure blade coating, gravure coating, rod blade coating, short dwell coating, curtain coating, die coating and the like. After coating and drying the coating solution for the heat-sensitive recording layer on the support by an appropriate coating method,
Further, the barrier layer coating liquid is formed on the heat-sensitive recording layer by a method such as coating and drying.

The support is appropriately selected from paper (neutral paper, acidic paper), plastic film, synthetic paper, nonwoven fabric, metal deposit, and the like. The coating amount of the heat-sensitive recording layer coating composition is by dry weight 2~12g / m ² preferably 3 to 7 g / m ² approximately, 0.5 to 10 g / m coating amount of the protective layer coating composition in a dry weight ² , preferably 1 to 5 g
/ M ² .

The method for forming the release layer and the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include the same methods as those for forming the heat-sensitive recording layer and the protective layer. The coating amount of the release layer mainly composed of silicone resin-based release agent 0.3~7g / m ² in solid weight, and preferably from 0.5 to 5 g / m ² approximately. Further, the coating amount of the pressure-sensitive adhesive layer is 3 to 50 as a solid amount.
g / m ^2, preferably from 5 to 30 g / m ² approximately. Each of the release layer and the pressure-sensitive adhesive layer is applied on the protective layer or on the entire back surface of the support, but may be applied partially. Also, regarding the method of forming the pressure-sensitive adhesive layer, after forming on the release layer, winding,
A method of transferring to the back side of the support is also possible.

Further, after each layer is applied, it is possible to apply a smoothing treatment such as super calendaring. It is desirable that the surface of the protective layer has a Beck smoothness of 500 seconds or more. In addition, a protective layer is also provided between the support and the pressure-sensitive adhesive layer, if necessary, to further enhance the preservability, or to have a main component of an organic or inorganic oil-absorbing pigment between the support and the heat-sensitive recording layer. Various known techniques in the heat-sensitive recording pressure-sensitive adhesive sheet manufacturing field, such as providing an undercoat layer, perforating the pressure-sensitive adhesive sheet, and part-coating the pressure-sensitive adhesive except for the edges and perforations by a printing method, are described below. It can be added as needed.

[0032]

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 to such specific Examples. Parts and% in Examples are parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 Preparation of Coating Solution for Undercoat Layer 60 parts of calcined clay [trade name: Ansilex, manufactured by EMC, oil absorption 110 ml / 100 g], 1 part of 40% aqueous solution of sodium polyacrylate, average particle diameter 4 of 1 μm hollow particles (film agent: polystyrene, film thickness: 0.3 μm)
80 parts of a 5% dispersion, 14 parts of a styrene / butadiene copolymer latex having a solid concentration of 48%, and a 10% aqueous solution of polyvinyl alcohol (saponification degree 88%, polymerization degree 1000) 5
A composition comprising 0 parts and 100 parts of water was mixed and stirred to obtain a coating liquid for an undercoat layer.

Preparation of Solution A 10 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluoran, 5% aqueous solution of methylcellulose 5
Parts and 40 parts of water were pulverized with a sand mill until the average particle size became 1.0 μm.

Preparation of Solution B Coloration wherein the weight ratio of 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) is 3.6: 1.0. A composition comprising 30 parts of an agent (trade name: D-77, manufactured by Nippon Soda Co., Ltd.), 5 parts of a 5% aqueous solution of methylcellulose, and 80 parts of water was pulverized by a sand mill until the average particle diameter became 0.6 μm.

Preparation of Solution C A composition comprising 10 parts of di-p-methylbenzyl oxalate, 10 parts of di-p-chlorobenzyl ester of oxalic acid, 5 parts of a 5% aqueous solution of methylcellulose and 55 parts of water was subjected to an average particle diameter by a sand mill. Was reduced to 1.0 μm.

Preparation of coating solution for heat-sensitive recording layer 55 parts of solution A, 115 parts of solution B, 80 parts of solution C, 10% of polyvinyl alcohol (degree of saponification 88%, degree of polymerization 1000)
A composition comprising 160 parts of an aqueous solution, 20 parts of a styrene / butadiene latex having a solid concentration of 50%, 17 parts of light calcium carbonate, 10 parts of a 40% aqueous solution of glyoxal, and 20 parts of a 20% aqueous solution of a polyamide epichlorohydrin resin is mixed and stirred. A coating solution for a heat-sensitive recording layer was obtained.

Preparation of Coating Solution for Protective Layer Acetoacetyl-modified polyvinyl alcohol [trade name:
GOSEFIMER Z200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.], 500 parts of a 10% aqueous solution, kaolin [trade name: UW-9]
80, manufactured by EC Co.] was mixed and stirred to obtain a coating liquid for a protective layer.

Preparation of Adhesive Sheet for Thermal Recording On one surface of neutral paper (support) having a basis weight of 64 g / m ^2, a coating liquid for an undercoat layer, a coating liquid for a thermosensitive recording layer, and a coating liquid for a protective layer are dried. The subsequent coating amounts were 9 g / m ² , 6 g / m ² , 3
g / m ² , followed by drying and then undercoating, heat-sensitive recording layer, and protective layer (each layer was subjected to a supercalender treatment, and the Bekk smoothness of the protective layer surface was 8).
00 seconds. ) To obtain a thermosensitive recording medium. Next, a coating liquid for an adhesive layer composed of an acrylic resin-based adhesive latex (solid concentration: 40%) is applied to the release layer surface of a commercially available release paper so that the applied amount after drying is 25 g / m ² and dried. Then, the pressure-sensitive adhesive layer was provided, and the other surface of the heat-sensitive recording medium was bonded to the pressure-sensitive adhesive layer to obtain a heat-sensitive recording pressure-sensitive adhesive sheet.

Example 2 In the preparation of Solution B of Example 1, 2,2'-bis [4-
Instead of 30 parts of the color former having a weight ratio of (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) of 3.6: 1.0, 2,
A colorant (trade name: D-90) in which the weight ratio of 2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) is 1.3: 1.0. A pressure-sensitive adhesive sheet for thermal recording was obtained in the same manner as in Example 1 except that 30 parts of Nippon Soda Co., Ltd. was used.

Example 3 In the preparation of solution B in Example 1, 2,2'-bis [4-
Instead of 30 parts of the color former having a weight ratio of (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) of 3.6: 1.0, 2,
20 parts of a coloring agent having a weight ratio of 2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether and the compound represented by the general formula (1) of 3.6: 1.0, and 4,4 ' -An adhesive sheet for thermal recording was obtained in the same manner as in Example 1 except that 10 parts of dihydroxydiphenylsulfone was used.

Example 4 In the preparation of the solution C of Example 1, 1,2-di (3- (3-methylbenzyl) ester was replaced with 1,2-di (3-methylbenzyl oxalate) instead of 10 parts of oxalic acid di-p-methylbenzyl ester. Example 1 except that 20 parts of methylphenoxy) ethane were used.
In the same manner as in the above, a heat-sensitive recording pressure-sensitive adhesive sheet was obtained.

Example 5 In the preparation of the coating solution for the thermosensitive recording layer of Example 1, 25 parts of a 20% aqueous solution of adipic dihydrazide was used instead of 10 parts of a 40% aqueous solution of glyoxal, Instead of 500 parts of a 10% aqueous solution of acetyl-modified polyvinyl alcohol [trade name: Gosefimer Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.], diacetone-modified polyvinyl alcohol [trade name: D-Polymer D-3480, manufactured by Unitika Ltd.] 10% aqueous solution of 500
A pressure-sensitive adhesive sheet for heat-sensitive recording was obtained in the same manner as in Example 1 except for using a part.

Example 6 In the preparation of the coating liquid for the protective layer of Example 1, 500 parts of a 10% aqueous solution of acetoacetyl-modified polyvinyl alcohol [trade name: Gosefimer Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.] was used instead. Then, a heat-sensitive recording pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that 500 parts of a 10% aqueous solution of carboxy-modified polyvinyl alcohol (trade name: Gosenal T215, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used.

Comparative Example 1 In the preparation of Solution B of Example 1, 2,2'-bis [4-
Instead of 30 parts of the color former having a weight ratio of (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by formula (1) of 3.6: 1.0, 4-
A heat-sensitive recording pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that 30 parts of hydroxy-4'-isopropoxydiphenylsulfone was used.

Comparative Example 2 In the preparation of Solution B of Example 1, 2,2′-bis [4-
Instead of 30 parts of the color former having a weight ratio of (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) of 3.6: 1.0, 2,
A heat-sensitive recording pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that 30 parts of 4'-dihydroxydiphenylsulfone was used.

Comparative Example 3 In the preparation of Solution B of Example 1, 2,2′-bis [4-
Instead of 30 parts of the color former having a weight ratio of (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) of 3.6: 1.0, 1,
A heat-sensitive recording pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that 30 parts of 1-bis (4-hydroxyphenyl) 1-phenylethane was used.

Comparative Example 4 In the preparation of Solution B of Example 1, 2,2′-bis [4-
Instead of 30 parts of the color former having a weight ratio of (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) of 3.6: 1.0, 2,
A heat-sensitive recording pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1, except that 30 parts of 2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether was used.

The following evaluation test was performed on the thus obtained pressure-sensitive adhesive sheet for heat-sensitive recording, and the results are shown in Table 1.

[Coloring property] Thermal recording evaluation machine (trade name: TH)
-PMD, manufactured by Okura Electric Co., Ltd.)
Record each thermosensitive recording adhesive sheet at 50 mJ / dot,
The density of the recording portion and the background portion were measured with a Macbeth densitometer (RD-9).
14 type, manufactured by Macbeth Corporation) in the visual mode.

[Plasticizer resistance] Polypropylene pipe (4
A wrap film (trade name: High Wrap KMA-W, manufactured by Mitsui Chemicals, Inc.) is wound three times on a 0 mmφ tube), and a heat-sensitive recording adhesive sheet after recording in recording density measurement is placed thereon, and further wrapped thereon After the film was wound three times and allowed to stand at 40 ° C. for 24 hours, the optical density of the recording portion was measured with the Macbeth densitometer to evaluate the plasticizer resistance.

[Water-resistant plasticizer] A wrap film (trade name: High Wrap KMA-W, manufactured by Mitsui Chemicals, Inc.) was wound three times on a polypropylene pipe (40 mm diameter pipe), and the heat sensitivity after recording in the measurement of recording density thereon A recording adhesive sheet was placed, a drop of water was dropped on the uppermost layer, and then a wrap film was further wrapped in triplicate, left at room temperature for 72 hours, and the optical density of the recording portion was measured with the Macbeth densitometer described above. To evaluate the plasticizer resistance.

[Hot water resistance: Microwave resistance] A heat sensitive recording adhesive sheet measured in the above color developing property was attached to a paper cover on a lid of a udon container sold by a convenience store (APM Japan) and consumed. After cooking in a microwave oven with a power of 500 W for 3 minutes, the background portion and the recording portion were covered with the Macbeth densitometer (trade name: RD-914).
Type, Macbeth)).

[0054]

[Table 1]

[0055]

As is clear from Table 1, the heat-sensitive recording pressure-sensitive adhesive sheet of the present invention has a heat-resistant preservation property for the background portion, a storage stability for the recording portion against chemicals such as a plasticizer and edible oil, and a water-resistant plasticizer. It is a heat-sensitive recording pressure-sensitive adhesive sheet excellent in heat resistance and suitable for use as a label for foods to be heated by a microwave oven.

Claims (3)

[Claims] 1. A support having a heat-sensitive recording layer containing a leuco dye and a coloring agent on one surface and a protective layer in order, and the other surface of the support containing a pressure-sensitive adhesive as a main component. In a heat-sensitive recording pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether is used as a colorant in the heat-sensitive recording layer and represented by the following general formula (1). Pressure-sensitive adhesive sheet for heat-sensitive recording, characterized by containing a compound to be prepared. Embedded image (In the general formula (1), n represents an integer of 1 to 3.) 2. The weight ratio of 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxydiethyl ether to the compound represented by the general formula (1) is from 1: 1 to 4: 1. The pressure-sensitive adhesive sheet for heat-sensitive recording according to the above. 3. A method of using a heat-sensitive recording pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the heat-sensitive recording pressure-sensitive adhesive sheet according to claim 1 is used as a label for foods to be heated by a microwave oven.