JPH1111021A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material having excellent color developability, little skin fog for heat, satisfactory storage stability of plasticizing resistance and oil resistance. SOLUTION: The thermal recording material comprises a thermal color developing layer provided on a support of paper, plastic sheet or synthetic paper. In this case, the layer contains color developable compound containing one selected from (1) bis(4-hydroxyphenyl)methylacetate, and (2) 1,1,3-tris(2- methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4,4'-butylidene-bis-(3-methyl-6-t- butylphenol) and 3,3',5,5'-tetrabrom-4,4'-dihydroxydiphenylsulfone.

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, and more particularly to a heat-sensitive recording material having excellent coloring properties, low background fog to heat, and good storage properties such as plasticizer resistance and oil resistance.

[0002]

2. Description of the Related Art A heat-sensitive recording material using a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance when heated is disclosed in JP-B-43-4160 and JP-B-45-14039.
And widely used. In general, a thermosensitive recording material is obtained by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles, and then mixing both.
Additives such as binders, sensitizers, fillers, lubricants, etc. are added to this to form a coating solution, which is applied to a support such as paper, film, synthetic paper, etc., and heated to produce a leuco dye and a developer. One or both of them is used to obtain a color recording by a chemical reaction caused by melting and contacting, and usually a sheet-like heat-sensitive recording material is prepared. A thermal printer with a built-in thermal head or the like is used for coloring the heat-sensitive recording sheet. Compared with other recording methods, this thermal recording method (1) produces no noise during recording, (2) does not require development and fixing,
(3) Maintenance-free. (4) Widely used in the facsimile field, computer output, printers such as calculators, recorders for medical measurement, automatic ticket vending machines, thermosensitive labeling, etc. Have been.

[0003] Among these fields of use, the use of POS systems in retail stores and supermarkets has led to the widespread use of labels and price tags. In particular, heat-sensitive labels affixed to fresh foods, lunch boxes, processed foods, etc. The image area is easily discolored by a packaging material (wrap film) containing a plasticizer, leaked edible oil or fat, and the background fog (coloration of the unprinted area) is likely to occur due to heat or humidity during heating or thawing. There is a problem.

In recent years, the demand for high-speed recording has been further increased, and the development of a heat-sensitive recording material for responding to the demand has been strongly desired. In general, however, if the sensitivity of the heat-sensitive recording material is increased to improve the thermal responsiveness, background fog will occur. The disadvantage that it occurs is likely to appear. Further, many of the above-mentioned preservability improvers, stabilizers, and the like used for improving the plasticizer resistance and oil resistance have a defect of causing a decrease in sensitivity and background fog. Conventionally, various methods have been proposed for improving heat responsiveness, excellent storage stability, and improving heat resistance and wet heat resistance of an unprinted portion, but a satisfactory method has not yet been established.

[0005] For example, Japanese Patent Publication No. 52-20142 discloses that the thermal responsive layer is improved in thermal responsiveness by increasing the smoothness of the heat-sensitive coloring layer by a super calendering process. In contrast, when the value is improved, there is a problem that the matching with the thermal head becomes poor. Japanese Patent Application Laid-Open No. 56-164890 discloses a method using a leuco dye having a low melting point. However, this method has a defect that heat fog is increased, although thermal response is improved. . Another method is to provide a specific intermediate layer between the support and the heat-sensitive recording layer.
5093, JP-A-60-248390, JP-A-1-
JP-A-113282, JP-A-2-214688 and the like are insufficient.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the disadvantages of the prior art as described above. That is,
An object of the present invention is to provide a heat-sensitive recording material having high sensitivity, excellent preservability of an image portion, and low background fog against heat and humidity.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to improve the above-mentioned drawbacks of the thermosensitive recording material, and as a result, completed the present invention. That is, the present invention relates to (1) a heat-sensitive recording material provided with a heat-sensitive color-forming layer comprising, as main components, a colorless or pale-colored color-forming compound and a color-developing compound capable of thermally generating the color-forming compound on a support. As the color-developing compound, (1) methyl bis (4-hydroxyphenyl) acetate and (2) 1,1,3-tris (2-methyl-4)
-Hydroxy-5-cyclohexylphenyl) butane,
4,4'-butylidene-bis- (3-methyl-6-t-
Butylphenol) and one selected from 3,3 ′, 5,5′-tetrabromo-4,4′-dihydroxydiphenylsulfone. (2) a thermosensitive coloring layer (1) The heat-sensitive recording material according to (1), wherein an intermediate layer is provided between the supports.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the heat-sensitive recording material of the present invention, the heat-sensitive color-forming layer contains a color-forming compound and a color-developing compound.
(1) methyl bis (4-hydroxyphenyl) acetate, and (2) 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4 ′
-Butylidene-bis- (3-methyl-6-t-butylphenol) and 3,3 ', 5,5'-tetrabromo-
One selected from 4,4'-dihydroxydiphenyl sulfone as a main component, a binder such as the following, and other fillers, if necessary, a heat-fusible compound, a lubricant, a surfactant, etc. Prepared by use.

The color-developing compound of the present invention comprises (1) bis (4-
(Hydroxyphenyl) acetic acid: (2) 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane or 4,4′-butyledene-bis- (3
-Methyl-6-t-butylphenol) or 3,3 ′,
A mixture of 5,5′-tetrabromo-4,4′-dihydroxydiphenylsulfone = 1: 2 to 10: 1 parts by weight, preferably 1: 1 to 5: 1 parts by weight, is mixed with 1 part by weight of the color-forming compound. It is used in a proportion of 1 to 10 parts by weight, preferably 2 to 5 parts by weight.

In forming the thermosensitive coloring layer in the present invention, the coloring compound is 1 to 50% by weight, methyl bis (4-hydroxyphenyl) acetate and 1,1,3-tris (2
-Methyl-4-hydroxy-5-cyclohexylphenyl) butane or 4,4'-butyledene-bis- (3-methyl-6-t-butylphenol) or 3,3 ', 5
The mixture of 5'-tetrabromo-4,4'-dihydroxydiphenylsulfone is 5 to 80% by weight, and the binder is 1 to 9%.
0% by weight, a filler and a heat-fusible compound are each used in an amount of 0 to 80% by weight, and other lubricants, surfactants and the like are used in arbitrary ratios.

In the present invention, the coating liquid comprising the above-described material is applied on the intermediate layer provided on the support in a dry weight of 1 to 5.
40 g / m ^2, preferably coated so that 5 to 15 g / m ^2, and dried thermosensitive coloring layer is formed. Further, a protective layer or the like can be provided on the thermosensitive coloring layer.

The color-forming compound used in the heat-sensitive color-forming layer can be used without particular limitation as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples of the color-forming compound that can be used include: For example, fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds,
Fluorene compounds and the like.

Among these, fluoran compounds include, for example, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl- N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3
-(N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluoran, 3-isobutylethylamino-6-methyl-7-anilinofluoran, 3- [N
-Ethyl-N- (3-ethoxypropyl) amino] -6
-Methyl-7-anilinofluoran, 3- (N-ethyl-N-hexylamino) -6-methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran, 3-
(N-ethyl-N-tetrahydrofurylamino) -6
Methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (p-chloroanilino) fluoran, 3-diethylamino-6-methyl-7- (p-fluoroanilino) fluoran, 3- (p- Toluidinoethylamino) -6-methyl-7-anilinofluoran, 3
-Diethylamino-6-methyl-7- (p-toluidino) fluoran, 3-diethylamino-7- (3,4-
Dichloroanilino) fluorane, 3-pyrrolidino-6
Methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran,
3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3
-Diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-dibutylamino-7-
(O-fluoroanilino) fluoran, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7- Phenylfluorane, 3- (p-toluidinoethylamino) -6-methyl-7-phenethylfluoran and the like.

The triarylmethane compounds include, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL), 3,3-bis (p
-Dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylaminoindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methyl Indole-3-
Yl) phthalide, 3- (p-dimethylaminophenyl)
-3- (2-Phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-
Yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide,
3,3- (2-phenylindol-3-yl) -5
Dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like.

Further, as the spiro compound, for example, 3
-Methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzopyran ) Spiropyran, 1,3,3-trimethyl-6
-Nitro-8'-methoxyspiro (indoline-2,
2′-benzopyran) and the like as diphenylmethane-based compounds, for example, N-halophenyl-leukoauramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4,5-trichlorophenylleucoura As a thiazine-based compound, for example, benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue, and as a lactam-based compound, for example, rhodamine B anilinolactam,
Rhodamine B-p-chloroanilinolactam and the like are fluorene-based compounds, for example, 3,6-bis (dimethylamino) fluorenespiro (9,3 ′)-6′-dimethylaminophthalide, 3,6-bis (Dimethylamino)
Fluorene spiro (9,3 ')-6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorene spiro (9,3')-6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

The color-developing compounds that can be used in combination other than the above-described color-developing compounds can be used without any particular limitation as long as they are generally used in pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples of the color developing compound that can be used include, for example, α-naphthol, β-naphthol, p-octylphenol,
-T-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) propane (alias: bisphenol A or BPA), 2,2-bis (p-hydroxyphenyl) butane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 4,4′-thiobisphenol, 4,4′-
Cyclohexylidenediphenol, 2,2 ′-(2,5
-Dibromo-4-hydroxyphenyl) propane, 4,
4-isopropylidenebis (2-t-butylphenol), 2,2′-methylenebis (4-chlorophenol), 4,4′-dihydroxydiphenylsulfone,
2,4'-dihydroxydiphenyl sulfone, bis (3
-Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone,
4-hydroxy-4′-butoxydiphenyl sulfone,
Butyl bis- (4-hydroxyphenyl) acetate, bis-
Phenolic compounds such as benzyl (4-hydroxyphenyl) acetate and 2,4-dihydroxy-2'-methoxybenzanilide; benzyl p-hydroxybenzoate;
Such as ethyl hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, and 3,5-di-α-methylbenzylsalicylic acid; Examples thereof include aromatic carboxylic acid derivatives, aromatic carboxylic acids and metal salts thereof.

In the present invention, specific examples of the binder which can be used for providing the intermediate layer, the thermosensitive coloring layer and the protective layer include methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose and polyvinyl alcohol (PVA). ), Carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, silyl group-modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid,
Water-soluble ones such as starch and derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salts of styrene / maleic anhydride copolymer, iso (or diiso) butylene / maleic anhydride copolymer salt, and styrene / Butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, polyvinyl acetate, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polystyrene ,
Acrylic resin, acrylic / styrene resin, polyacrylate, polyester, polycarbonate, polyurethane, polybutyral, epoxy resin, furan resin,
Examples include hydrophobic polymer compounds such as vinyl toluene resin, rosin ester resin, composite particles of colloidal silica and acrylic copolymer, and emulsions thereof.

Examples of fillers that can be used include calcium carbonate, magnesium carbonate, magnesium oxide, silica,
Examples include white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, acrylic resin, polyolefin resin, benzoguanamine resin, melamine resin, and urea-formalin resin.

Examples of heat-fusible compounds that can be used include waxes such as animal and vegetable waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, acetylated aromatic amines, naphthalene derivatives, and aromatic ethers. And aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, terphenyl derivatives, etc., which are solid at ordinary temperature and have a melting point of about 70 ° C. or more can be used.

Examples of waxes include wood wax, carnauba wax, shellac, paraffin, montan wax,
Paraffin oxide, polyethylene wax, polyethylene oxide and the like, as higher fatty acids, for example, stearic acid,
Examples of higher fatty acid amides such as behenic acid include stearic acid amide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, and ethylenebisstearin Acid amides and the like; higher fatty acid anilides such as stearic acid anilide and linoleic acid anilide; acetylated aromatic amines such as acetotoluide; naphthalene derivatives such as 1-benzyloxynaphthalene and 2-benzyloxynaphthalene; Benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and the like include aromatic ethers such as 1,2-diphenoxyethane, 1,4
-Diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methoxyphenoxy) ethane, 1,2-bis (3,4-dimethylphenyl) ethane, 1-phenoxy- 2- (4-chlorophenoxy) ethane, 1-phenoxy-2- (4-methoxyphenoxy) ethane and the like include aromatic carboxylic acid derivatives such as benzyl p-hydroxybenzoate,
Examples of aromatic sulfonic acid ester derivatives include benzyl p-benzyloxybenzoate and dibenzyl terephthalate, for example, p-toluenesulfonic acid phenyl ester, phenylmesitylene sulfonate,
-Methylphenyl mesitylenesulfonate and the like are carbonic acid or oxalic acid diester derivatives, for example, diphenyl carbonate, dibenzyl oxalate, dioxalate (4
-Methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester and the like, as biphenyl derivatives,
For example, p-benzylbiphenyl, p-allyloxybiphenyl and the like are terphenyl derivatives such as m-
Terphenyl and the like are each exemplified.

In addition, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, defoamers, ultraviolet absorbers and the like can be added as required.

When an intermediate layer is provided between the heat-sensitive color-forming layer and the support, the color-forming properties become better. The coating agent for this intermediate layer is
It is prepared by using the above-mentioned filler and binder as main components and using a crosslinking agent and various surfactants as necessary. Filler: Binder 20: 1 to 1: 5, preferably 10: 1
Used in a weight ratio of １1: 1. In general, the filler is preferably an organic polystyrene resin, an acrylic resin, a polyolefin resin, a benzoguanamine resin, a melamine resin, a urea-formalin resin or the like having a large heat insulating property, and preferably has an average particle diameter of 0.4 to 2 μm. .

In order to enhance the effect of the binder, it is preferable to use a crosslinking agent in combination. Examples of the crosslinking agent that can be used include glyoxal, formalin, borax, aziridine, dialdehyde starch, melamine resin, polyethyleneimine resin, polyamide / epichlorohydrin resin, ketone / aldehyde resin, epoxy resin, glycine, glycidyl ester, glycidyl ether, Ketene dimer, dimethylol urea, ammonium chloride, magnesium chloride, calcium chloride, aluminum sulfate, magnesium sulfate,
Examples include calcium hydroxide and zirconium ammonium carbonate.

The amount of the crosslinking agent to be used is 0.1 to
It is used in an amount of 50% by weight, preferably 1 to 20% by weight.

The heat-sensitive recording material of the present invention is prepared by using the above-mentioned materials by, for example, the following method. That is, first, a filler and a binder and, if necessary, a crosslinking agent, a wetting agent, an antifoaming agent, and the like are mixed and dispersed via water or an organic solvent such as toluene or IPA to prepare an intermediate layer coating solution. Then, the composition is coated on a support such as paper, plastic sheet, synthetic paper or the like by a bar coater, a blade coater, or the like so that the weight when dried is 1 to 40 g / m ² , preferably 5 to 20 g / m ^2. To form an intermediate layer. Next, methyl bis (4-hydroxyphenyl) acetate and 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane,
4'-butylidene-bis- (3-methyl-6-t-butylphenol), 3,3 ', 5,5'-tetrabromo-
After one selected from 4,4′-dihydroxydiphenyl sulfone is separately pulverized and dispersed together with a binder or other additives as necessary using a disperser such as a ball mill, an attritor, or a sand mill (pulverization, When the dispersion is carried out by a wet method, water is usually used as a medium) and mixed to prepare a coating solution for the heat-sensitive coloring layer, and the intermediate layer is formed on the intermediate layer so as to have a dry weight of 1 to 40 g / m ^2. (The ratio of the color-forming compound to the color-developing compound is usually from 2: 1 to 1:10 in terms of dry weight ratio), and dried to form a heat-sensitive color-forming layer. Obtain the recording material.
Further, if necessary, an overcoat layer may be provided on the thermosensitive coloring layer.

As the color developing compound, methyl bis (4-hydroxyphenyl) acetate and 1,1,3
-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-butylidene-bis- (3-methyl-6-t-butylphenol), 3,
The heat-sensitive recording material of the present invention containing one selected from 3 ', 5,5'-tetrabromo-4,4'-dihydroxydiphenylsulfone is excellent in color developability, has low background fog to heat, and is resistant to plasticity. Excellent storage stability such as chemical properties and oil resistance.

[0027]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicates parts by weight.

Example 1 (Formation of Intermediate Layer) An intermediate layer coating solution having the following ratio was prepared and dried on a high-quality paper having a basis weight of 50 g / m ² to a weight of 8%.
g / m ² and dried to form an intermediate layer. 48% polystyrene fine particle dispersion (average particle size: 0.5 μm) 166 parts 40% styrene / acrylate copolymer emulsion 50 parts Water 34 parts

(Formation of a thermosensitive coloring layer) A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle size became 2 μm or less, and the solution [A] and the solution [B] were respectively obtained.
A solution and a solution [C] are prepared. [A] solution: 3-dibutylamino-6-methyl-7-anilinofluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] solution: methyl bis (4-hydroxyphenyl) acetate (CAS Reg. No. 5129-00-0)) 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [C] liquid: 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, (CAS Reg.No.111850-25-25) 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, the respective preparations are mixed at the following ratios to prepare a coating solution for the thermosensitive coloring layer, coated on the above-mentioned intermediate layer so that the weight when dried is 7 g / m ^2, and dried to form a thermosensitive coloring. Get the layers. [A] solution 8 parts [B] solution 20 parts [C] solution 10 parts 50% calcium carbonate dispersion 8 parts 48% carboxylated styrene / butadiene copolymer latex 4 parts water 10 parts (formation of protective layer) The protective layer coating solution having the following ratio is applied onto the thermosensitive coloring layer so as to have a dry weight of 3 g / m ² and dried to obtain the thermosensitive recording material of the present invention. 15% carboxyl group-modified PVA aqueous solution 100 parts 20% colloidal silica dispersion 25 parts 30% glyoxal aqueous solution 1 part

[0031] Example 2 in place of the intermediate layer coating solution of Example 1, the intermediate layer coating solution was prepared, a basis weight of 50 g / weight of dry the fine paper of m ² is 15 g / m ² composed of the following proportions Is applied and dried to form an intermediate layer, and then the heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1. 30% polymethyl methacrylate fine particle dispersion liquid (average particle diameter 1 μm) 133 parts 40% styrene / acrylate copolymer emulsion 100 parts Water 17 parts

Example 3 25% of 4,4'-butylidene-bis- (3-methyl-6), which was similarly ground and dispersed in place of the solution [C] of Example 1, was used.
-T-butylphenol) (CAS Reg. No. 8)
5-60-9) The heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1 using the dispersion.

Example 4 Instead of the solution [C] in Example 1, 25% 3,3 ', 5,5'-tetrabromo-4,4'-pulverized and dispersed in the same manner.
Dihydroxydiphenyl sulfone (CAS No. 39
635-79-5) The heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1 using the dispersion liquid.

Example 5 A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the coating solution for the thermosensitive coloring layer prepared in Example 1 was used instead of the coating solution for the thermosensitive coloring layer of Example 1. [A] liquid 8 parts [B] liquid 20 parts [C] liquid 4 parts 20% methylol stearic acid amide dispersion 5 parts 50% calcium carbonate dispersion 8 parts 48% carboxylated styrene / butadiene copolymer latex 4 parts water 10 copies

Example 6 In place of 3-dibutylamino-6-methyl-7-anilinofluoran of Example 1, 3-diisopentylamino-
The heat-sensitive recording material of the present invention is obtained in the same manner as in Example 1 using 6-methyl-7-anilinofluorane.

Comparative Example 1 A mixture [D] was prepared by pulverizing and dispersing a mixture having the following composition using a sand grinder so that the average particle size became 2 μm or less. Solution [D]: 4-hydroxy-4'-isopropoxydiphenyl sulfone 25 parts 25% aqueous PVA solution 20 parts Water 55 parts Instead of solution [B] and solution [C] of Example 1, solution [D] was used. In the same manner as in Example 1, a comparative thermosensitive recording material is obtained.

Tables 1 and 2 show the quality performance of the heat-sensitive recording materials of the present invention and the comparative examples obtained as described above.

[0038]

Table 1 Quality performance test Background 1) Color density 2) Color density 3) Heat resistance 4) Heat resistance 5) Example 1 0.04 1.54 1.47 0.18 0.43 Example 2 0.04 1.55 1.49 0.18 0.44 Example 3 0.04 1.54 1.48 0.18 0.43 Example 4 0.04 1.60 1.60 0.19 0.10 46 Example 5 0.04 1.54 1.55 0.18 0.44 Example 6 0.04 1.55 1.55 0.15 0.39 Comparative Example 1 0.04 1.56 1.17 0 .65 1.56

[0039]

[Table 2]

The methods of the quality performance tests listed in Tables 1 and 2 are as follows. 1) Background: The uncolored sample was measured using a Macbeth reflection densitometer R
The value measured with Model D-914. 2) Coloring density: Macbeth reflection density of a printed portion of a sample printed using a commercially available POS label printer with printing energy of normal use. 3) Color density: Macbeth reflection density of a printing portion when printing is performed at a printing energy for high-speed use of the printer. 4) Heat resistance: Macbeth reflection density of a sample in which a hot plate at 100 ° C. was applied for 1 second at a printing pressure of 1 kg / cm ² for coloring. 5) Heat resistance: Macbeth reflection density of a sample in which a hot plate at 110 ° C. was applied at a printing pressure of 1 kg / cm ² for 1 second to form a color. 6) Plasticizer resistance: The sample printed by the above printer was converted to PV
Residual rate (%) of the print density after leaving the C-wrap film on both sides at room temperature for 24 hours under a load of 300 g / cm ² . 7) Oil resistance: Residual rate (%) of the density of a printed portion after applying salad oil on a sample printed by the above printer and leaving it at room temperature for 24 hours.

As is clear from the table, the heat-sensitive recording material of the present invention is excellent in color developability, and excellent in heat resistance of the background portion against heat, storage stability of the color developed portion such as plasticizer resistance and oil resistance.

[0042]

EFFECT OF THE INVENTION As a color developing compound in the thermosensitive coloring layer,
(1) methyl bis (4-hydroxyphenyl) acetate, and (2) 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4 ′
-Butylidene-bis- (3-methyl-6-t-butylphenol), 3,3 ', 5,5'-tetrabromo-4,
The heat-sensitive recording material of the present invention containing one selected from 4'-dihydroxydiphenyl sulfone is excellent in coloring properties, has little background fog to heat, and is excellent in plasticizer resistance and oil resistance storage stability. I have.

Claims (2)

[Claims] 1. A thermosensitive recording material comprising a support having thereon a heat-sensitive color-forming layer comprising a colorless or pale-colored color-forming compound and a color-developing compound capable of coloring the color-forming compound when heated. (1) methyl bis (4-hydroxyphenyl) acetate, and (2) 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4′-butylidene -Bis- (3
-Methyl-6-t-butylphenol) and 3,
A heat-sensitive recording material comprising one selected from 3 ', 5,5'-tetrabromo-4,4'-dihydroxydiphenylsulfone. 2. The heat-sensitive recording material according to claim 1, wherein an intermediate layer is provided between the heat-sensitive coloring layer and the support.