JP2001232947A - Thermal recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording sheet excellent in color forming sensitivity, good in image preservability especially under high temperature and high humidity environment and prevented from powdering. SOLUTION: A dihydroxydiphenylsulfone compound represented by general formula (1) (wherein, R1 and R2 are each a 1-8C alkyl group, an alkenyl group or a halogen atom; and p and q are each an integer of 0-3) is added to the thermal color forming layer of the thermal recording sheet as a developer and a compound represented by formula (2) and a saturated fatty acid monoamide represented by general formula (3) (wherein, R3 is a 11-21C alkyl group) are added to the thermal color forming layer thereof.

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 sheet excellent in color sensitivity and image stability and free from dusting.

[0002]

2. Description of the Related Art A thermosensitive recording medium having a thermosensitive coloring layer mainly composed of a colorless or pale-colored dye precursor and a color developing agent which reacts with the dye precursor by heating to form a color is disclosed in JP-B-45-14.
No. 039, which is widely used. In order to perform recording on this thermal recording medium, a thermal printer or the like having a built-in thermal head is used, but such a thermal recording method is compared with other recording methods that have been practically used in the past.
With features such as no noise at the time of recording, no need for development and fixing, maintenance-free, relatively inexpensive and compact equipment, and very clear color development, with the development of the information industry, Widely used in facsimile and computer fields, various measuring instruments, labels, etc., as these recording devices become more diversified and have higher performance, the required quality of thermal recording media has become higher. ing. As for the recording speed, as the size of the apparatus is reduced and the recording speed is increased, it is required that a clear color image with a high density can be obtained even with minute heat energy. Further, with the spread of applications using the heat-sensitive recording medium, there are many occasions where the thermosensitive recording medium is used under high temperature and high humidity conditions such as outdoors, and it is required to maintain stability even in a severe environment.

In order to satisfy these requirements, as a method for increasing the color-forming sensitivity, for example, a method of adding a heat-soluble substance to a heat-sensitive layer described in JP-A-56-169087, and a method of JP-A-56-144193. However, it is difficult to say that sufficient quality can be obtained due to the drawbacks such as the occurrence of dusting with the passage of time. Was. Further, in the case of a method in which a dye and a developer are further used in combination with a suitable sensitizer, for example, when the developer is a phenolic compound represented by bisphenol A, p-benzylbiphenyl (JP-A-60-1985)
82382), benzyl p-benzyloxybenzoate (JP-A-57-201691), benzylnaphthyl ether (JP-A-58-87094) and the like have been used as suitable sensitizers. In the case of using a sensitizer, when heated, the sensitizer first melts, and this dissolves the dye and the developer so that they are mixed at the molecular level to induce a color-forming reaction. It is necessary to individually examine compatibility with the combination with the coloring agent.

The dihydroxydiphenylsulfone compound used as an organic color developer in the present invention is a conventionally known compound, but has a low color-forming ability and cannot meet the recent demand for high sensitivity. JP-A-8-67070 describes a method of adding a solid solution of two oxalic acid ester derivatives as a method of increasing color development sensitivity. However, although the color development sensitivity is slightly increased, dusting and image storability over time are not improved. It is hardly enough. As described above, the color sensitivity was increased, and other quality requirements such as image stability could not be satisfied.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording sheet which is excellent in color-forming sensitivity, has good image storability especially in a high-humidity environment, and prevents dusting. .

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a thermosensitive recording medium provided with a thermosensitive coloring layer containing a colorless or pale-colored basic colorless dye and an organic color developer as main components. The thermosensitive coloring layer contains at least one kind of a dihydroxydiphenylsulfone compound represented by the following general formula (1) as an organic developer, and a compound represented by the following formula (2) and a compound represented by the following general formula (3). A heat-sensitive recording sheet comprising at least one of the following saturated fatty acid monoamides.

[0007]

Embedded image (In the formula, R ₁ and R ₂ represent an alkyl group, an alkenyl group or a halogen atom having 1 to 8 carbon atoms, and p and q each represent an integer of 0 to _3. )

[0008]

Embedded image

[0009]

Embedded image (In the formula, R ₃ represents an alkyl group having 11 to 21 carbon atoms.)

It is generally assumed that the color development sensitivity of a thermosensitive recording medium is affected by the melt-dissolution diffusion rate of the dye and the developer and the saturation solubility. In order to improve these, a method of adding various materials as a sensitizer is adopted, and the addition of the sensitizer lowers the melting point, changes the polarity, lowers the activation energy, and improves the compatibility between the materials. It is considered that the factors work in a complicated manner, and the melt-dissolution diffusion rate and the saturation solubility are further increased, and thus the color sensitivity of the thermosensitive recording medium is improved.

The reason why a thermosensitive recording medium of excellent quality can be obtained in the present invention has not been elucidated yet, but the compound represented by the formula (2) and the saturated fatty acid monoamide represented by the general formula (3) are not clearly understood. It is considered that both have an amide group and are excellent in compatibility, so that the compatibility of each of the other materials is also improved, the color sensitivity is increased, and dusting is less likely to occur. The color image is formed of a charge transfer complex formed by a heat melting reaction between a dihydroxydiphenyl sulfone compound represented by the general formula (1) used as an organic developer and a basic colorless dye. The compound represented by the formula (2) and the saturated fatty acid monoamide are also melted by heat at the same time as the developer and the basic colorless dye react with each other and incorporated into the charge transfer complex, thereby maintaining the bonding force inside the complex. Therefore, it is considered that a stable charge transfer complex is obtained and the image storability is enhanced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to obtain a thermosensitive recording medium of the present invention,
For example, a dispersion in which a dye, a compound represented by the general formula (1), a compound represented by the general formula (2), or a compound represented by the general formula (3) is dispersed together with a binder is mixed, and a filler and other necessary additives are added thereto to form a thermosensitive coloring layer The thermosensitive recording medium of the present invention can be produced by preparing a thermosensitive coloring layer by preparing a liquid and applying and drying the solution on a substrate.

In the present invention, an organic developer represented by the general formula (1)
A dihydroxydiphenylsulfone compound represented by the formula: Specific examples of the compound represented by the general formula (1) include: 4,4'-dihydroxydiphenylsulfone (1-1) 2,4'-dihydroxydiphenylsulfone (1-2) bis- (3-allyl- 4-Hydroxyphenyl) sulfone (1-3) 3,3'-dimethyl-4,4'-dihydroxydiphenyl sulfone (1-4) 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxy Diphenyl sulfone (1-5) 2,2'-bis (4-chlorophenol) sulfone (1
-6) 4-Hydroxyphenyl-3'-isopropyl-4'-
Hydroxyphenyl sulfone (1-7) bis- (3-ethyl-4-hydroxyphenyl) sulfone (1-8) 2,2'-bis (pt-butylphenol) sulfone (1-9) 2,2'- Bis (pt-pentylphenol) sulfone (1-10) 2,2'-bis (pt-octylphenol) sulfone (1-11) and the like, but are not limited thereto.
Among them, (1-1) to (1-3) are preferably used because they have good sensitivity and heat resistance and are easily available. These developers may be used alone or in combination of two or more.

In the present invention, a compound represented by the formula (2) is used. The compound represented by the formula (2) is desirably used in a ratio of 0.1 to 2 parts with respect to 1 part of the organic color developer, and particularly when 0.3 to 1.5 parts is contained. Good quality is more preferable. In the present invention, a saturated fatty acid monoamide represented by the general formula (3) is used. The saturated fatty acid monoamide is desirably used in a ratio of 0.1 to 2 parts with respect to 1 part of the organic developer, and particularly when 0.3 to 1.5 parts are contained, very good quality is obtained. More preferred. In the present invention, the ratio of the compound represented by the formula (2) to the saturated fatty acid monoamide is 2: 1.
In the case of １ ： 1: 2, a good balance of quality such as color development sensitivity and image storability is preferred.

In the general formula (3), R ₃ represents a hydrocarbon group, specifically, an alkyl group having 11 to 21 carbon atoms. Specific examples of the compound represented by the general formula (3) include 3-1 to 3-4 shown below, but are not limited thereto. Among them, 3-2 and 3-3
The mixture of 3-2 and 3-3 is particularly preferably used because of its good color development sensitivity and the like when used together.

[0016]

Embedded image

As the leuco-developing basic leuco dye used in the present invention, any of those known in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and there is no particular limitation, but triphenylmethane. Compounds, fluorane compounds, fluorene compounds, divinyl compounds and the like are preferred. Specific examples of typical colorless or pale color dyes (dye precursors) are shown below. These dye precursors may be used alone or in combination of two or more.

<Triphenylmethane leuco dye> 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] 3,3-bis (p-dimethylaminophenyl) phthalide [ Malachite green lactone] <Fluoran leuco dye> 3-Diethylamino-6-methylfluoran 3-Diethylamino-6-methyl-7-anilinofluoran 3-Diethylamino-6-methyl-7- (o, p-dimethyl Anilino) fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-7- (o- Chloroanilino) fluoran 3-diethylamino-6-meth Le-7- (p-chloroanilino) fluoran 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-diethylamino-6-methyl-7- (m-methylanilino) fluoran 3-diethylamino-6 Methyl-7-n-octylanilinofluoran 3-diethylamino-6-methyl-7-n-octylaminofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl- 7-dibenzylanilinofluoran 3-diethylamino-6-chloro-7-methylfluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-chloro-7-p-methylanilino Fluoran 3-diethylamino-6-ethoxyethyl-7-anilinov Oran 3-diethylamino-7-methylfluoran 3-diethylamino-7-chlorofluoran 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-7- (o-chloroanilino) fluoran 3-diethylamino -7- (p-chloroanilino) fluoran 3-diethylamino-7- (o-fluoroanilino) fluoran 3-diethylamino-benzo [a] fluoran 3-diethylamino-benzo [c] fluoran 3-dibutylamino-6-methyl- Fluoran 3-dibutylamino-6-methyl-7-anilinofluoran

3-dibutylamino-6-methyl-7-
(O, p-dimethylanilino) fluoran 3-dibutylamino-6-methyl-7- (o-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (p-chloroanilino) fluoran 3-dibutylamino-6 -Methyl-7- (o-fluoroanilino) fluoran 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-dibutylamino-6-methyl-chlorofluoran 3-dibutylamino -6-ethoxyethyl-7-anilinofluoran 3-dibutylamino-6-chloro-7-anilinofluoran 3-dibutylamino-6-methyl-7-p-methylanilinofluoran 3-dibutylamino- 7- (o-chloroanilino) fluoran 3-dibutylamino-7- (o-fluoroanilino) fur Oran 3-di-n-pentylamino-6-methyl-7-anilinofluoran 3-di-n-pentylamino-6-methyl-7- (p-
Chloroanilino) fluorane 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluoran 3-di-n-pentylamino-6-chloro-7-anilinofluoran 3-di-n-pentyl Amino-7- (p-chloroanilino) fluoran 3-pyrrolidino-6-methyl-7-anilinofluoran 3-piperidino-6-methyl-7-anilinofluoran 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran 3- (N-methyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-xylamino) -6-methyl-
7- (p-chloroanilino) fluoran 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilino Fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-ethoxypropylamino) -6
-Methyl-7-anilinofluoran

3-cyclohexylamino-6-chlorofluoran 2- (4-oxahexyl) -3-dimethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-diethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-dipropylamino-
6-methyl-7-anilinofluoran 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluoran 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluoran 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluoran 2,4-dimethyl- 6-[(4-dimethylamino) anilino] -fluoran

<Fluorene Leuco Dye>3,6,6'-Tris (dimethylamino) spiro [fluorene-9,3'-phthalide] 3,6,6'-Tris (diethylamino) spiro [fluorene-9,3 '-Phthalide] <Divinyl leuco dye> 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5,
6,7-tetrabromophthalide 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5,
6,7-tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide 3,3- Bis- [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide <Others> 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide 3,3-bis (1-ethyl-2-methylindole-3
-Yl) phthalide 3,6-bis (diethylamino) fluoran-γ- (3
'-Nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (4
'-Nitro) anilinolactam 1,1-bis- [2', 2 ', 2 ", 2" -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-dinitrileethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2-
β-naphthoylethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-Diacetylethane bis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

Above all, 3-di-n-pentylamino-6-methyl-7-anilinofluoran is preferably used because of its excellent ground whiteness and heat resistance. Generally, it is considered that coloring of a coating liquid is caused by a part of a material contained in the coating liquid being dissolved in water and reacting with a dye. For example, 4,4'-dihydroxydiphenylsulfone, which is a kind of the compound represented by the general formula (1), has two -OH groups which are considered to form a basic colorless dye, and has a polarity of the molecule itself. Relatively high and easily soluble in water, but 3-di-n-pentylamino-6-methyl-7-
Anilinofluoran has a solubility in water of 1.349 ×
Since it is as low as 10 ^-6 g / l or less, 3-di-n-pentylamino-6 is used together with the compound represented by the general formula (1).
It is presumed that the use of -methyl-7-anilinofluoran can specifically suppress the coloring of the paint.

In the present invention, conventionally known sensitizers can be used as long as the desired effects on the above objects are not impaired. Such sensitizers include ethylene bisamide, montanic acid wax, polyethylene wax,
1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β-benzyloxynaphthalene, 4
-Biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, 4,4'-ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di (3 -Methylphenoxy) ethylene, 1,2-diphenoxyethylene, bis [2- (4-methoxy-phenoxy) ethyl] ether, methyl p-nitrobenzoate, dibenzyl oxalate,
Di (p-chlorobenzyl) oxalate, di (p-chlorobenzyl)
Methylbenzyl), dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-
Examples include diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, o-xylene-bis- (phenyl ether), 4- (m-methylphenoxymethyl) biphenyl, orthotoluenesulfonamide, and paratoluenesulfonamide. , But not limited to these. These sensitizers may be used alone or in combination of two or more.

The binder used in the present invention is a completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, a partially saponified polyvinyl alcohol, a carboxy-modified polyvinyl alcohol, an amide-modified polyvinyl alcohol, a sulfonic acid-modified polyvinyl alcohol, a butyral-modified polyvinyl alcohol. Alcohol, other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and cellulose derivatives such as ethyl cellulose, acetyl cellulose, polyvinyl chloride, polyacetic acid vinyl,
Examples thereof include polyacrylamide, polyacrylate, polyvinylbutylalal, polystyrene and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and cumaro resin. These macromolecules are water, alcohol, ketone,
In addition to dissolving in solvents such as esters and hydrocarbons,
It is used in a state of being emulsified or dispersed in water or another medium in the form of a paste, and may be used in combination depending on required quality.

In the present invention, 4,4'-butylidene (6-t-butyl-3) is used as an image stabilizer which exhibits an oil resistance effect of a recorded image, as long as the desired effect on the above-mentioned object is not impaired. -Methylphenol) 2,2'-di-t-butyl-5,5'-dimethyl-4,
4'-Sulfonyldiphenol 1,1,3-tris (2-methyl-4-hydroxy-5
-Cyclohexylphenyl) butane 1,1,3-tris (2-methyl-4-hydroxy-5
-T-butylphenyl) butane 4-benzyloxy-4 '-(2,3-epoxy-2-
Methylpropoxy) diphenylsulfone epoxy resin and the like can also be added.

The filler used in the present invention includes silica,
Examples include inorganic or organic fillers such as calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide. In addition, lubricants such as waxes, benzophenone-based or triazole-based ultraviolet absorbers, water-proofing agents such as glyoxal, dispersants, defoamers, antioxidants, fluorescent dyes, and the like can be used.

The amounts of the color developer and dye used in the heat-sensitive recording medium of the present invention and the types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited. , A developer 1 represented by the general formula (1)
Parts to 0.1 to 2 parts of a basic colorless dye and 0.5 parts of a filler
４4 parts are used, and the binder is suitably used in an amount of 5-25% of the total solid content. The desired heat-sensitive recording sheet can be obtained by applying the coating solution having the above composition to any support such as paper, recycled paper, synthetic paper, film, plastic film, foamed plastic film, nonwoven fabric, and gold foil. Further, a composite sheet obtained by combining these may be used as the support. Further, an overcoat layer of a polymer substance or the like can be provided on the thermosensitive coloring layer for the purpose of enhancing the storage stability. In addition, an undercoat layer of a polymer material containing a filler or the like can be provided below the heat-sensitive layer for the purpose of increasing the coloring sensitivity.

The above-mentioned organic developer, basic colorless dye and, if necessary, materials to be added are finely divided by a pulverizer such as a ball mill, an attritor, a sand glider or an appropriate emulsifier until the particle diameter becomes several microns or less. And a binder and various kinds of additive materials are added according to the purpose to obtain a coating liquid. The means for applying is not particularly limited, and can be applied according to a well-known conventional technique, for example, an off-machine coating machine equipped with various coaters such as an air knife coater, a rod blade coater, a bill blade coater, and a roll coater, and an on-machine coating machine. A machine coating machine is appropriately selected and used.

[0029]

The present invention will be described below with reference to examples.
In addition, in description, a part shows a weight part. [Example 1] Dispersions having the following compositions were prepared in advance for the respective materials of the dye, the developer, and the sensitizer, and wet grinding was performed by a sand grinder until the average particle diameter became 1 micron. <Developer dispersion>4,4'-dihydroxydiphenyl sulfone (BPS) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts <Dye dispersion> 3-di-n-pentylamino- 6-methyl-7-anilinofluoran (Black305) 3.0 parts 10% aqueous solution of polyvinyl alcohol 6.9 parts Water 3.9 parts <Compound dispersion of formula (2)> Compound of formula (2) 6.0 Part 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts <Saturated fatty acid monoamide dispersion> (3-3) compound 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts Were mixed to obtain a heat-sensitive layer coating liquid. The coating amount after drying this coating liquid on a high-quality paper having a basis weight of 50 g / m ² is 6 g / m ^2.
The coating was dried so as to give a Beck smoothness of 200 to 600 seconds using a super calender to obtain a thermosensitive recording medium. Developer dispersion 36.0 parts Dye dispersion 13.8 parts Compound dispersion of formula (2) 30.0 parts Saturated fatty acid monoamide dispersion 6.0 parts Kaolin clay 50% dispersion 26.0 parts Zinc stearate 6.7 parts of 30% dispersion

Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the number of parts of the compound dispersion of the formula (2) and the saturated fatty acid monoamide dispersion were changed as follows. Compound (2) dispersion 24.0 parts Saturated fatty acid monoamide dispersion 12.0 parts

Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the number of parts of the compound dispersion of the formula (2) and the saturated fatty acid monoamide dispersion were changed as follows. Compound of formula (2) 18.0 parts Saturated fatty acid monoamide dispersion 18.0 parts

Example 4 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the number of parts of the compound dispersion of the formula (2) and the saturated fatty acid monoamide dispersion were changed as follows. Compound dispersion of formula (2) 12.0 parts Saturated fatty acid monoamide dispersion 24.0 parts

Example 5 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the number of parts of the compound dispersion of the formula (2) and the saturated fatty acid monoamide dispersion were changed as follows. Compound dispersion of formula (2) 6.0 parts Saturated fatty acid monoamide dispersion 30.0 parts

[Comparative Example 1] In Example 1, the formula (2)
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 36.0 parts of a saturated fatty acid monoamide dispersion was blended without compounding the compound dispersion of Formula (1).

Comparative Example 2 Thermal recording was carried out in the same manner as in Example 1, except that the saturated fatty acid monoamide dispersion was not blended and the compound dispersion of the formula (2) was blended in an amount of 36.0 parts. I got a body.

Comparative Example 3 In Example 1, the formula (2)
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the compound dispersion of (1) and the saturated fatty acid monoamide dispersion were not blended, and 36.0 parts of the following sensitizer dispersion were blended. <1,2-bis (phenoxymethyl) benzene dispersion> 1,2-bis (phenoxymethyl) benzene (PMB2) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts

Comparative Example 4 The procedure of Example 3 was repeated except that the developer dispersion was changed from 4,4'-dihydroxydiphenylsulfone to 4,4'-isopropylidenediphenol (BPA). To obtain a thermosensitive recording medium.

The following quality performance tests were performed on the thermal recording media obtained in the above Examples and Comparative Examples, and the results are shown in Table 1. In the column of the sensitizer in Table 1, PAT represents the compound represented by the formula (2), and AP represents saturated fatty acid monoamide, and the number represents the number of blending parts. (1) Coloring Sensitivity Using TH-PMD manufactured by Okura Electric Co., printing was performed on the created thermal recording medium at an applied energy of 0.34 mj / dot. The image density after printing and after the quality test was measured with a Macbeth densitometer (using an amber filter). (2) Residual ratio of image area after high-humidity preservation treatment.
After standing for 24 hours in an atmosphere of H, the image area was measured with a Macbeth densitometer. The image remaining rate was calculated from the Macbeth density before and after the test by the following calculation method.

Equation 1 Image Residual Rate (%) = (Macbeth Density After Test) / (Macbeth Density Before Test) × 100 (3) Powder Wiping 24 mJ / using a UBI printer (manufactured by UBI).
After the image portion printed in mm ² was left indoors for 24 hours, the state of dusting of the image portion was visually evaluated. ◎ None ○ Almost none △ Somewhat × Yes

[0039]

[Table 1]

As is clear from the above results, Examples 1 to 5 in which the compound represented by the formula (2) and the saturated fatty acid monoamide were contained in the heat-sensitive color-forming layer exhibited color sensitivity, high temperature and high humidity. The image portion was excellent in moisture resistance and quality such as dusting prevention. Above all, Example 2 in which the ratio of the compound represented by the formula (2) to the saturated fatty acid monoamide is 2: 1 to 1: 2.
The quality of ~ 4 is better. On the other hand, in Comparative Examples 1 and 2 containing only one of the compound represented by the formula (2) and the saturated fatty acid monoamide, a thermosensitive recording medium having a well-balanced quality was not obtained. Further, even if a different sensitizer was used with respect to the developer specified in the present invention, no improvement in color development was observed, and Comparative Example 5, in which the developer specified in the present invention was not used, showed a preservation of the image area. It was inferior in sex.

[0041]

According to the present invention, fax paper, printers, etc. are obtained because they have high color development sensitivity, good image storability in a high temperature and high humidity environment, and excellent quality such as suppression of dusting. In applications widely and generally used as thermal paper, such as paper and cashier paper, it is possible to provide a higher-quality and reliable thermal recording medium.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tomonori Sekine 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Japan Paper Manufacturing Co., Ltd. (72) Toshio Kaneko 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo No. Japan Paper Manufacturing Co., Ltd. Product Development Laboratory F-term (reference) 2H026 AA07 BB28 DD02 DD12 DD14 DD43 DD45 DD53

Claims (1)

[Claims] 1. A heat-sensitive recording sheet comprising a support sheet and a heat-sensitive coloring layer containing a colorless or light-colored basic colorless dye and an organic color developing agent as main components, wherein the heat-sensitive color developing layer comprises an organic color developing agent. Contains at least one dihydroxydiphenylsulfone compound represented by the following general formula (1), and comprises at least one compound represented by the following formula (2) and at least one saturated fatty acid monoamide represented by the following general formula (3). A heat-sensitive recording sheet characterized by containing various types. Embedded image (In the formula, R ₁ and R ₂ represent an alkyl group, an alkenyl group or a halogen atom having 1 to 8 carbon atoms, and p and q each represent an integer of 0 to 3.) Embedded image (In the formula, R ₃ represents an alkyl group having 11 to 21 carbon atoms.)