JPH061074A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain excellent color-developing capacity by forming a colorless or light-colored dye precursor formed onto at least one surface of a sheet base body and a thermal color-developing layer containing a developer in specific general formula being reacted with the dye precursor under heating and color- developing the precursor. CONSTITUTION:A compound in formula 1 (R<1> and R<2> represent a hydogen atom, a lower alkyl group, an aryl group, an aralkyl group or a halogen atom respectively independently, (m) and (n) the integers of 1-5 mutually indenpendently and respectively and R' and R'' hydrocarbon groups forming cyclic structure together with a part of a benzene ring, with which each of R<1> and R<2> bond, and may form polynucleus aromatic ring structure together with the benzene ring) functions as a developer when a color-developing image is shaped by utilizing the color reaction of a colorless or light-colored dye precursor and the developer capable of color-developing under heating with the dye precursor. The compound in formula 1 has an amino group activated by an adjacent sulfonyl group, thus displaying intense color-developing capacity in the dye precursor.

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 on which a color-formed image is formed by heating, and more particularly to a heat-sensitive recording material having excellent storage stability of the color-formed image. More specifically, the present invention has a high long-term storability of a recorded image, and at the same time is excellent in moisture resistance of recording, environment resistance such as heat resistance, and oil resistance, and plasticizer resistance. The present invention relates to a thermal recording material useful for applications such as facsimile paper, cash dispenser paper, boarding tickets, commuter passes, labels such as POS labels, cards such as prepaid cards, and pass tickets.

[0002]

2. Description of the Related Art A heat-sensitive recording material is generally composed of a support such as paper, synthetic paper, or plastic film on which a color-forming substance such as an electron-donating leuco dye and an organic compound such as an electron-accepting phenolic compound. A thermosensitive coloring layer mainly composed of a color-developing substance such as an acidic substance is provided, and a recorded image can be obtained by reacting the color-developing substance with the color-developing substance by thermal energy. is there. (For example, it is disclosed in JP-B-43-4160, JP-B-45-14039, and JP-B-48-27736, and is widely put into practical use.)

The thermosensitive recording medium having the above structure has a compact recording apparatus, is inexpensive, and is easy to maintain. Therefore, the output of a computer, a facsimile, an automatic ticket vending machine, a printer for scientific measuring instruments, or Widely used in CRTs, printers for medical measurement, etc. However, in the case of a conventional so-called dye-type thermosensitive recording medium obtained by coating a thermosensitive coloring layer containing a color-developing dye substance, a color-developing substance and a binder on the support, It is known that the color-developed image disappears over time because the color-developing reaction is reversible. This decoloring is accelerated under exposure to light, high humidity, and high temperature, and further progresses rapidly due to contact with a plasticizer, oil, etc., and the image is erased to an unreadable level.

A number of techniques have been disclosed in order to suppress this decoloring phenomenon in a color-forming system using a color-forming system which usually uses a dye precursor mainly composed of a colorless or light-colored lactone ring compound. They are, for example, JP-A-60-787.
82, JP-A-59-167292, JP-A-59-1.
No. 14096 and a compound containing a phenolic antioxidant as described in JP-A-59-93387 in a thermosensitive color developing layer, and a hydrophobic polymer compound emulsion as disclosed in JP-A-56-146796. And a protective layer or a surface layer including the above.

However, even a thermal recording paper containing a phenolic material is not very effective in improving the heat resistance and humidity resistance of an image. Conversely, the addition of an antioxidant causes
Defects such as a decrease in whiteness of the resulting thermal recording paper may be noticeable. On the other hand, a thermal recording medium provided with a protective layer or a surface layer has considerably improved environmental resistance for a short time, but image erasing is inevitable during long-term storage. Further, in this technique, since a heat insulating layer is formed on the surface of the thermosensitive recording paper, a decrease in recording sensitivity cannot be avoided.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems in the prior art and is excellent in oil resistance, plasticizer resistance, moisture resistance, heat resistance, etc. of color images, and therefore excellent long-term storage stability. It is an object of the present invention to provide a thermal recording material having The heat-sensitive recording material with improved storability according to the present invention can be used, for example, as a heat-sensitive recording type ticket for an automatic ticket vending machine, and can also be used for a coupon ticket or a commuter ticket that requires long-term storage, and It is also useful as a facsimile paper for storage, a word processor paper, and an image printer paper for CRT.

[0007]

The present inventors have investigated an improved method for improving the long-term storage stability of a color image, and as a result, a carbonylsulfonamide compound having a specific chemical structure has an excellent color development. The present invention has been completed by demonstrating its ability and having a higher image storability than conventional color developers.

The thermal recording material of the present invention comprises a sheet-shaped substrate,
Formed on at least one surface of the sheet-like substrate, and
A colorless or light-colored dye precursor, and a heat-sensitive color-developing layer containing a color-developing agent that reacts with this dye precursor under heating to develop a color, and the color-developing agent has the following general formula (I):

[Chemical 2] (However, R ¹ and R ² each independently represent a hydrogen atom, a lower alkyl group, an aryl group, an aralkyl group, or a halogen atom, and m and n each independently represent an integer of 1 to 5. And R ¹ and R ² are
Each is a hydrocarbon group that forms a cyclic structure with a part of the benzene ring to which it is bonded, and may form a polynuclear aromatic ring structure with the benzene ring. And at least one compound represented by the formula (1).

[0009]

The compound of the formula (I) used in the present invention is a coloration of a colorless or pale basic leuco dye (dye precursor) and a developer capable of developing the dye precursor under heating. It acts as a developer when forming a colored image by utilizing the reaction. That is, since the compound of formula (I) has an amino group activated by an adjacent sulfonyl group, it exhibits a strong developing ability with respect to a basic leuco dye. Whether or not the hydroxyl group in the ortho position to the carbonyl group itself enhances the color reaction as a phenolic hydroxyl group or further activates the amino group by its substituent effect is not yet clear enough. Absent.

The following compounds may be mentioned as specific examples of the compound of the general formula (I). N- (o-hydroxybenzoyl) -p-toluenesulfonamide, N- (o-hydroxy-p-toluoyl)
-P-toluenesulfonamide, N- (2-hydroxy-3-phenylbenzoyl) -p-toluenesulfonamide, N- (2-hydroxy-5-tert-butylbenzoyl) -p-toluenesulfonamide, N- ( 2-
Hydroxy-5-tert-octylbenzoyl) -p
-Toluenesulfonamide, N- (1-hydroxy-2
-Naphthylcarbonyl) -p-toluenesulfonamide, N- (o-hydroxy-p-toluoyl) -benzenesulfonamide, N- (o-hydroxy-m-toluoyl) -o-toluenesulfonamide, N- (o- Hydroxy-p-toluoyl) -p-chlorobenzenesulfonamide, N- (o-hydroxy-p-benzylbenzoyl) -p-toluenesulfonamide, N- (o-hydroxy-p-toluoyl) -mesitylenesulfonamide. These compounds may be used alone or as a mixture of two or more thereof.

Many of the compounds of formula (I) as described above are
It is a novel compound that has not been reported so far, and its synthesis can be carried out, for example, by the following reaction.

[Chemical 3] (However, R ¹ and R ² are as defined above, and m and n are also as defined above.)

The leuco dyes used as the dye precursor in the present invention are triphenylmethane type, fluorane type,
It can be selected from conventionally known compounds such as diphenylmethane compounds. For example, 3- (4-diethylamino-2
-Ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, crystal violet lactone, 3- (N-ethyl-N-isopentylamino) -6-methyl-7- Anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-
(O, p-dimethylanilino) fluorane, 3- (N-
Ethyl-N-p-toluidino) -6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-
7-anilinofluorane, 3- (N-cyclohexyl-
N-methylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7-
(M-trifluoromethylanilino) fluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane,
3-diethylamino-6-methylfluorane, and 3
-Cyclohexylamino-6-chlorofluorane, 3-
(N-ethyl-N-hexylamino) -6-methyl-7
1 selected from-(p-chloroanilino) fluorane, etc.
More than one species can be used.

Further, in order to further improve the storability of the color image in the thermosensitive color layer, specifically, the conventional color image such as oil or a plasticizer is completely erased in an extremely short time. An aromatic compound having at least one aziridinyl group or an aromatic compound having at least one epoxy group may be further contained in order to further improve the resistance to a substance that causes it.

Specific examples of these aromatic compounds having at least one aziridinyl group or aromatic compounds having at least one epoxy group are described in JP-A-62-1.
No. 64579, JP-A No. 2-220885, and JP-A No. 2-255376, the following compounds can be given as examples.

Epoxy group-containing aromatic compound 4,4'-bis (2 ", 3" -epoxypropyloxy) diphenyl sulfone, 2,2-bis [4'-
(2 ", 3" -epoxypropyloxy) phenyl] propane, 1,4-bis (2 ', 3'-epoxypropyloxy) benzene, 4- (2'-methyl-2', 3'-
Epoxypropyloxy) -4'-benzyloxy-diphenylsulfone, 4- (2 ", 3" -epoxypropyloxy) -4 '-(p-methylbenzyloxy) -diphenylsulfone, epoxidized ortho novolak cresol resin, 4 , 4'-bis (2 ", 3" -epoxypropyloxy) -diphenylmethane, 4,4'-bis (2 ", 3" -epoxypropylamino) -diphenylmethane, bis (2 ", 3" -epoxypropyl) -4
4'-methylenedibenzoate, 4,4'-bis (2 ", 3" -epoxypropyloxy) biphenyl,
4,4'-bis (2 ", 3" -epoxypropyloxy) 3,3 ', 5,5'-tetramethylbiphenyl,
2,6-bis (2 ', 3'-epoxypropyloxy)
Naphthalene, bis (2,3-epoxypropyl) terephthalate.

Aziridinyl aromatic compound 2,4-bis (1- aziridinylcarbonylamino ) toluene, bis [4- (1- aziridinylcarbonylamino ) phenyl] methane, bis [3-chloro-4- (1 −
Aziridinylcarbonylamino) phenyl] methane,
2,2-bis [4- (1-aziridinylcarbonyloxy) phenyl] propane, 1,4-bis (1-aziridinylcarbonyloxy) benzene, 1,4-bis (1-
Aziridinylcarbonyl) benzene.

Further, in the present invention, a conventionally known developer containing a phenol or an organic acid may be used in combination with the compound of the formula (I) of the present invention within a range not inhibiting the desired effect. . As these conventional color developers, for example,
2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [1-methyl-1- (4′- Hydroxyphenyl) ethyl] benzene, 1,3-bis [1-methyl-1- (4'-hydroxyphenyl) ethyl] benzene, dihydroxydiphenyl ether (JP-A-1-180382), benzyl p-hydroxybenzoate (JP-A-1) Sho 52-140483
No.), bisphenol S, 4-hydroxy-4'-isopropyloxydiphenyl sulfone (JP-A-60-13).
852), 1,1-di (4-hydroxyphenyl) cyclohexane, 1,7-di (4-hydroxyphenylthio) -3,5-dioxaheptane (JP-A-59-526).
94), 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone (JP-A-60-208286).
Etc. can be used.

Further, in the present invention, it is preferable to use a heat-fusible substance (so-called sensitizer) in the heat-sensitive color forming layer. As the sensitizer, a heat-fusible organic compound having a melting point of 50 to 150 ° C. is used, and examples thereof include 1-hydroxy-2-naphthoic acid phenyl ester (JP-A-57-19).
1089), p-benzylbiphenyl (JP-A-60-
82382), benzyl naphthyl ether (Japanese Patent Application Laid-open No. Sho 5)
8-87094), dibenzyl terephthalate (JP-A-58-98285), benzyl p-benzyloxybenzoate (JP-A-57-201691), diphenyl carbonate, ditolyl carbonate (JP-A-58-136489). ,
m-terphenyl (JP-A-57-89994), 1,
2-bis (m-tolyloxy) ethane (JP-A-60-5)
6588), 1,5-bis (p-methoxyphenoxy) -3-oxapentane (JP-A-62-181183).
No.), oxalic acid diesters (JP-A-64-1583).
No.), 1,4-bis (p-tolyloxy) benzene (JP-A-2-1537873), diphenyl sulfone (JP-B-59-25673), p-toluenesulfonic acid phenyl ester (JP-A-59-73990). , Mesitylene sulfonic acid p-tolyl ester (JP-A-2-8028)
5), 4,4'-diallyloxydiphenyl sulfone, 4,4'-diisopentyloxydiphenyl sulfone, 4,4'-dimethoxydiphenyl sulfone (Japanese Patent Publication No. 2-9951), 4,4'-di- It can be selected from n-pentyloxydiphenyl sulfone (JP-A-60-47070) and the like.

The thermosensitive coloring layer of the present invention may further contain a hindered phenol compound or an ultraviolet absorber. They are disclosed, for example, in JP-A-57-151394,
JP-A-58-160191, JP-A-58-69096
JP-A-59-2884, JP-A-59-95190
JP-A-60-22288 and JP-A-60-2554.
85, JP-A-61-44686, JP-A-62-16
9683, JP-A-63-17081, JP-A-1-249385 and the like.
Specifically, for example, 1,1,3-tris (3′-cyclohexyl-4′-hydroxyphenyl) butane, 1,
1,3-tris (2-methyl-4-hydroxy-5-t
ert-butylphenyl) butane, 4,4′-thiobis (3-methyl-6-tert-butylphenol),
1,3,5-Trimethyl-2,4,6-tris (3,5
-Di-tert-butyl-4-hydroxybenzyl) benzene, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, p-octylphenyl salicylate, 2- (2'-hydroxy-5'-methylphenyl)
Benzotriazole, ethyl-2-cyano-3,3'-
Diphenyl acrylate, tetra (2,2,6,6,-
Tetramethyl-4-piperidyl) 1,2,3,4-butane tetracarboate and the like.

The heat-sensitive color forming layer of the heat-sensitive recording material of the present invention mainly contains a leuco dye and the compound of the above formula (I) of the present invention, and optionally a sensitizer and other additives. The heat-sensitive color forming layer preferably further contains an aromatic compound having at least one aziridinyl group or an aromatic compound having at least one epoxy group, if necessary. Further, the heat-sensitive color developing layer can contain conventionally known phenol-based or organic acid-based color developers, antioxidants, ultraviolet absorbers, or waxes, and preferably contains organic or inorganic pigments. . The heat-sensitive color forming layer contains a binder for fixing these components to the support.

The content of the leuco dye in the thermosensitive coloring layer is generally preferably 5 to 20% by weight based on the dry weight of the thermosensitive coloring layer. The content of the developer compound of formula (I) of the present invention is generally preferably 10 to 50% by weight. When the content of the compound of the formula (I) is less than 10% by weight, the color developing ability is insufficient, and even when it is added in excess of 50% by weight, the color developing ability is saturated and a remarkable improvement is seen. Not be done and it may be economically disadvantageous. When the above-mentioned epoxy compound or aziridine compound is contained in the thermosensitive coloring layer, its content is preferably 1 to 30% by weight based on the weight of the thermosensitive coloring layer. If the content is less than 1%, the image storage stability effect is small, and even if it is used in a large amount over 30% by weight, the effect of improving the storage stability is saturated and no further improvement is observed.

When the thermosensitive coloring layer contains an antioxidant or an ultraviolet absorber, its content is preferably 1 to 10% by weight. When a conventionally known phenol-based or organic acid-based developer is used in combination, its content is preferably 5 to 40% by weight based on the total amount of the developer. The content of the sensitizer is preferably 10 to 40% by weight. When waxes and white pigments are contained in the thermosensitive color developing layer, their contents are preferably 5 to 20% by weight and 10 to 50% by weight, respectively, and the binder content is generally 5% by weight.
Is about 20% by weight.

Examples of the above-mentioned organic or inorganic pigments include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, calcined clay, talc, and surface-treated calcium carbonate. Inorganic fine powder such as silica and silica, urea-formalin resin, styrene / methacrylic acid copolymer,
And organic fine powder such as polystyrene resin.

As the waxes, known waxes such as paraffin, amide wax, bisimide wax, and metal salt of higher fatty acid can be used.

Regarding the binder, polyvinyl alcohols having various molecular weights, starch and its derivatives, cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester Polymers, acrylic acid amides / acrylic acid esters / methacrylic acid terpolymers, styrene / maleic anhydride copolymers alkaline salts, polyacrylamides, sodium alginates, gelatin, and water-soluble polymeric materials such as casein, and
Polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic ester,
Each latex such as vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / butadiene / acrylic copolymer can be used.

The sheet-like substrate used in the heat-sensitive recording material of the present invention is paper, coated paper having a surface coated with a pigment and / or latex, laminated paper, synthetic paper made from polyolefin resin, and plastic. You can choose from film etc. At least one surface of such a sheet-like substrate is coated with a coating solution containing a mixture of the above-mentioned required components and dried to form a thermosensitive coloring layer, thereby producing a thermosensitive recording material. The coating amount of the thermosensitive coloring layer is preferably ¹ to 15 g / m ² when the coating liquid layer is dried,
² to 10 g / m ² is particularly preferable.

In the heat-sensitive recording material of the present invention, a coating layer such as a protective layer and a printing layer can be further formed on the heat-sensitive color forming layer.

[0028]

The present invention will be further described with reference to the following examples.
In Examples and Comparative Examples, "part" unless otherwise specified.
And "%" means "part by weight" and "% by weight", respectively.
Represents

Synthesis Example 1 N- (o-hydroxy-p-to
Luoyl) -p-toluenesulfonamide synthesis In a three-necked flask equipped with a dropping funnel, a thermometer, and a reflux condenser, 22.8 g of m-cresotoic acid and 14.1 g of
7. Phenol was added and the mixture was stirred with a magnetic stirrer at room temperature from a dropping funnel.
8 g of phosphorus oxychloride was added dropwise. After the dropping was completed, the reaction suspension was reacted at 60 ° C. for 4 hours.

After completion of the reaction, the reaction solution was cooled to room temperature, poured into 120 ml of 13% sodium carbonate aqueous solution, and stirred vigorously. The obtained suspension was shaken with a separating funnel, ether was added thereto to extract an ether-soluble substance, magnesium sulfate was added to this extract, and the mixture was dried overnight. The reaction product solution was filtered to remove magnesium sulfate, and then the filtrate was concentrated. The concentrate was cooled to give yellowish white crystals. Melting point 44 [deg.] C.

To 11.4 g of this yellowish white crystal, 10.4 g of potassium carbonate and 10.3 g of p-toluenesulfoamide were added and mixed, and the mixture was heated and melted at 130.degree. Foaming from this melt was confirmed during the reaction and allowed to react for about 2 to 3 hours. After cooling, this melt was extracted with a 5% aqueous sodium carbonate solution, and hydrochloric acid was added to this extract to make it acidic, whereby crystals were precipitated. White crystals were obtained by filtration. 13.7g
White crystals of N- (o-hydroxy-p-toluoyl) -p-toluenesulfonamide were obtained. Its melting point was 214 ° C.

Further, it was identified by NMR measurement that the obtained compound was the desired product. NMR measurement (heavy CD
The results are as follows. δ = 2.3 (s, 3H), 2.45 (s, 3H), 6.
7 (t, 2H), 7.35 (d, 3H), 8.05
(D, 2H).

Synthesis Example 2 N- (o-hydroxybenzoi
Synthesis of p) -p-toluenesulfonamide The same synthetic procedure as in Synthetic Example 1 was performed. However, 22.8g
20.7 g of salicylic acid was used in place of m-cresotoic acid of. 13.1 g of N- (o-hydroxybenzoyl) -p-toluenesulfonamide white crystals were obtained.
Its melting point was 173 ° C. By NMR measurement, the obtained compound was identified as the above target product.

Synthesis Example 3 N- (2-hydroxy-3- phenyl)
Phenylbenzoyl) -p-toluenesulfonamide
The same synthetic operation as in Synthesis Example 1 was performed. However, 22.8g
32 g of 3-phenylsalicylic acid was used in place of the m-crestoic acid of 1., and the reaction suspension after the dropwise addition of phosphorus oxychloride was reacted at 80 to 100 ° C. After the completion of the reaction in the second step, the melt solidified by cooling, was washed with water and ethanol, and was recrystallized from ethanol to give 10.1 g.
N- (2-hydroxy-3-phenylbenzoyl)-
White crystals of p-toluenesulfonamide were obtained.

By NMR measurement, it was identified that the obtained compound was the desired product. NMR measurement (heavy DMSO
Middle) The results are as follows. δ = 2.35 (s, 3H), 6.8 (t, 1H), 7.
23 to 7.45 (m, 6H), 7.55 (d, 2H),
7.75 (3,2H).

Synthesis Example 4 N- (1-hydroxy-2-na)
Futylcarbonyl) -p-toluenesulfonamide
Forming a thermometer, and reflux condenser in a two-neck flask fitted with a, put toluene 30 ml, further 1-hydroxy-2-naphthoic acid phenyl 23.8 g, potassium carbonate 18.7g and 18.5g of p- toluene Sulfamide was added and mixed, heated and dissolved at 100 ° C., and reacted for 2 to 3 hours. After the reaction was completed, the reaction product was cooled to room temperature, and the solidified reaction product was washed with water and toluene and recrystallized from ethanol.
4.6 g of white crystals of N- (1-hydroxy-2-naphthylcarbonyl) -p-toluenesulfonamide were obtained. Its melting point was 265 ° C.

By NMR measurement, the obtained compound was identified as the desired product. NMR measurement (heavy DMSO
Middle) The results are as follows. δ = 2.35 (s, 3H), 7.2 (m, 3H), 7.
48 (m, 2H), 7.78 (m, 4H), 8.22
(D, 1H).

Example 1 A thermosensitive recording paper was prepared by the following operation. (1) dispersion A prepared Component Parts by weight 3- (N- isopentyl -N- ethylamino) sand grinder to 20 6-methyl-7-anilinofluoran polyvinyl alcohol 10% solution 10 Water 70 The composition It was crushed and crushed until the average particle size became 1 μm or less.

(2) Dispersion B Preparation Component Weight Part N- (o-hydroxybenzoyl) -p-10 Toluenesulfonamide Oxalic acid di (p-methylbenzyl) ester 10 Polyvinyl alcohol 10% liquid 10 Water 70 The above composition The product was pulverized using a sand grinder until the average particle size became 1 μm or less.

(3) Preparation of Pigmented Undercoat Paper 85 parts of calcined clay (trademark: Ansilex) was added to 320 parts of water.
40 parts of styrene-butadiene copolymer emulsion (solid content 50%) and 10 parts of
% A coating liquid obtained by mixing the oxidized starch solution 50 parts, on a base paper basis weight of 48 g / m ^2, the coating amount after drying was coated so as to 7.0 g / m ² A pigment-coated paper was prepared.

(4) Formation of Thermosensitive Coloring Layer 30 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, in 50 parts of solution A and 200 parts of solution B,
15 parts of a 30% paraffin dispersion and 100 parts of a 10% aqueous solution of polyvinyl alcohol were mixed and stirred to prepare a coating liquid. This coating solution, on one side of the pigment-undercoated paper,
A thermosensitive coloring layer was formed by coating and drying so that the coating amount after drying was 5.0 g / m ^2, and a thermosensitive recording paper was prepared.

(5) Calender treatment The thermal recording paper obtained as described above was treated with a super calender to obtain a surface smoothness of 800 to 100.
It was set to 0 seconds.

(6) Color development test With respect to the above-mentioned thermal recording paper samples, a dynamic color development tester obtained by modifying a commercial thermal facsimile machine manufactured by Hitachi Ltd. was used.
The sample was colored with an applied energy of 0.44 mj / dot. The color density was measured with a Macbeth reflection densitometer RD-914. The test results are shown in Table 1.

Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in preparing the dispersion liquid B, instead of N- (o-hydroxybenzoyl) -p-toluenesulfonamide,
N- (o-hydroxy-p-toluoyl) -p-toluenesulfonamide was used. The test results are shown in Table 1.

Example 3 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in preparing the dispersion liquid B, instead of N- (o-hydroxybenzoyl) -p-toluenesulfonamide,
N- (1-hydroxy-2-naphthylcarbonyl) -p
-Toluenesulfonamide was used. Table 1 shows the test results
Shown in.

Comparative Example 1 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in preparing the dispersion liquid B, instead of N- (o-hydroxybenzoyl) -p-toluenesulfonamide,
2,2-bis (4-hydroxyphenyl) propane (bisphenol A) was used. The test results are shown in Table 1.

[0047]

[Table 1]

Example 4 A thermosensitive recording paper was prepared by the following operation. (1) Dispersion C Preparation Component Weight Part Bis [4- (1-aziridinylcarbonyl 20 amino) phenyl] methane Polyvinyl alcohol 10% liquid 10 Water 70 The above composition was used to obtain an average particle size using a sand grinder. It was pulverized until it became 1 μm or less.

(2) Formation of thermosensitive coloring layer 50 parts of solution A and 200 parts of solution B described in Example 1,
50 parts of the C liquid, 23 parts of calcium carbonate pigment, 25 parts
% Zinc stearate dispersion liquid 20 parts, 30% paraffin dispersion liquid 15 parts, and 10% polyvinyl alcohol aqueous solution 120 parts were mixed and stirred to prepare a coating liquid. This coating solution was applied to one surface of the pigment-undercoated paper described in Example 1 so that the coating amount after drying was 5.0 g / m ² to form a thermosensitive color-developing layer to prepare a thermosensitive recording paper. did.

The thermal recording paper obtained as described above was subjected to the super calendar treatment described in Example 1, and thereafter,
The color development test described in Example 1 was performed.

The color density was measured by Macbeth reflection densitometer RD-91.
4 and then make a predetermined test piece from this color-developed sample, apply dioctyl terephthalate (representative plasticizer) within 30 minutes after color development, and leave at room temperature for 3 hours, then wipe off excess plasticizer The residual image density was measured again with a Macbeth reflection densitometer, and this was used as a value representative of image storability. The test results are shown in Table 2.

Example 5 A thermosensitive recording paper was prepared in the same manner as in Example 4. However, in the preparation of the liquid B used for forming the thermosensitive coloring layer, N
N- (o-hydroxy-p-toluoyl) -p-toluenesulfonamide was used instead of-(o-hydroxybenzoyl) -p-toluenesulfonamide. The test results are shown in Table 2.

Comparative Example 2 The image storability test described in Example 4 was carried out using the sample of Comparative Example 1. The test results are shown in Table 2.

[0054]

[Table 2]

As is clear from Table 1 above, the novel developer compound of the present invention has a coloring ability comparable to that of bisphenol A, which is a representative of conventional developer. Further, as is clear from Table 2 above, the heat-sensitive recording material using the novel developer of the present invention in combination with the aziridine compound exhibits better plasticizer resistance immediately after color development.

[0056]

The thermosensitive recording material of the present invention contains a carbonylsulfonamide compound having a specific chemical structure (formula (I)) as a developer in the thermosensitive coloring layer. , Shows a coloring ability comparable to that of conventional developers. Further, when the thermosensitive coloring layer further contains an aziridine compound, the obtained colored image shows good plasticizer resistance.

Claims (1)

[Claims] 1. A sheet-like substrate, a colorless or light-colored dye precursor which is formed on at least one surface of the sheet-like substrate, and a developer which reacts with the dye precursor under heating to develop a color thereof. And a thermosensitive color-developing layer containing, wherein the developer has the following general formula (I): (However, R ¹ and R ² each independently represent a hydrogen atom, a lower alkyl group, an aryl group, an aralkyl group, or a halogen atom, and m and n each independently represent 1 to 5 Represents an integer and is also R ¹ and R ²
Are each a hydrocarbon group forming a cyclic structure with a part of the benzene ring to which it is bonded, and may form a polynuclear aromatic ring structure together with the benzene ring. ), Which contains at least one compound, a thermosensitive recording medium.