JPH09327972A - Thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording material wherein image retention and heat resistant ground color stability are drastically improved. SOLUTION: A thermal recording material is provided wherein a compound having an N-formamide group (-NHCHO) and a carbonylsulfonamide group (-SO2 NHCO-) which are expressed by the formula (wherein either of A1 or A2 is an N-formamide group, and the other expresses a hydrogen atom, R1 or R2 respectively independently expresses a hydrogen atom, an alkyl group, an alkoxyl group, a halogen atom, an acyl group, an alkokyl carbonyl group, and substituted or non-substituted aryl group.) is used as a developer. Though the compound has not a phenolic OH group, it has a developing capability for coloring a dye precursor with the N-formamide group and the carbonylsulfonamide group which present an acidic atmosphere. Further, by being compared with a conventionally used phenolic developer or the like, propeties which are excellent in image retention of a recording part and heat resistant ground color stability are presented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium using a compound having an N-formamide group and a carbonylsulfonamide group as a developer. Compared with a conventional color developer, it has excellent image storability of a recording portion and heat-resistant ground color stability of a blank portion, and is useful for applications requiring long-term storability of a recorded image.

[0002]

2. Description of the Related Art In general, a thermosensitive recording medium is prepared by grinding and dispersing a colorless or pale-colored dye precursor, which is usually an electron-donating compound, and a developer, which is an electron-accepting compound, into fine particles. A mixture obtained by mixing both and adding a binder, a filler, a sensitizer, a lubricant and other auxiliaries to a support such as paper, synthetic paper, film, plastic, etc. A color record is obtained by an instantaneous chemical reaction caused by heating of a stamp, a laser beam or the like. These thermosensitive recording materials include measurement recorders, computer terminal printers, facsimile machines, automatic ticket vending machines,
It is applied to a wide range of fields such as barcode labels.

However, with the recent diversification of recording devices for thermosensitive recording media and the development of higher performance, the quality required for thermosensitive recording media has become higher. In addition, with the spread of plain paper recording methods such as the electrophotographic method and the ink jet method, the thermal recording method has more opportunities to be compared with these plain paper recording methods. Therefore, for example, the stability of the recording portion (image) of the thermosensitive recording medium, or the stability of the non-recording portion (ground color portion or blank portion) before and after recording approaches the same level of quality as the plain paper recording method. Is required. In particular, from the viewpoint of storage stability of a recorded image, a heat-sensitive recording medium having excellent light resistance, oil resistance, water resistance, and plasticizer resistance has been required.

In order to solve these problems, an epoxy compound (Japanese Patent Application Laid-Open No. 4-97888), an aziridine compound (Japanese Patent Application Laid-Open No. 4-113888) and various kinds of metals are used in the heat-sensitive coloring layer for oil resistance and plasticizer resistance. An example containing a salt (JP-A-63-22683, etc.) is known. However, the effect is insufficient.

On the other hand, so-called non-phenolic color developers having an acidic atmosphere capable of coloring a dye precursor without having a hydroxy group have been developed in place of the conventionally used phenol color developers. is there. For example, a thiourea compound (Japanese Patent Application Laid-Open No. 58-21496), a carbonylsulfonamide compound (Japanese Patent Application Laid-Open No. 4-282291), an organic phosphorus compound (Japanese Patent Application Laid-Open No. 6-99666).
And the like. One of the causes of decolorization of the color image is the dissociation of the dye and the developer, but the non-phenolic developer is less soluble in water, oil, plasticizer, etc. than the conventional phenolic developer, It is considered that the image storability is improved. However, with some effect, the degree is still not enough.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium having improved image storability in the recording area and heat-resistant background color stability in the blank area.

[0007]

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that a compound having an N-formamide group and a carbonylsulfonamide group is used as a developer for a thermosensitive recording medium. The inventors have found that they exhibit excellent functions and completed the present invention. That is, the present invention is characterized in that the thermosensitive color-developing layer contains the compound represented by the following general formula (1).

[0008]

Embedded image (However, _one of A ₁ and A ₂ is an N-formamide group and the other is a hydrogen atom. R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an acyl group, Represents an alkoxycarbonyl group or a substituted or unsubstituted aryl group.)

The compound represented by the general formula (1) of the present invention does not have a phenolic OH group, unlike the conventionally used phenol type developers. However, N- formamide groups (-NHCHO) and carbonyl sulfonamide group (-SO ₂ NHCO-) has a developed ability to both develop the dye precursor. The carbonylsulfonamide group is already known as a color developing agent (Japanese Patent Laid-Open No. 2828/1992).
No. 2291 gazette), but even if it has a carbonylsulfonamide group alone, the effect is weak and it is difficult to obtain a sufficient color density. However, a compound having an N-formamide group at the same time was able to impart necessary and sufficient color developing ability for the first time. Although the detailed color development mechanism is not clear, one of the NH of the N-formamide group is bonded to CHO and the other is bonded to the phenyl group, and one of the NH of the carbonylsulfonamide group is bonded to SO ₂ and the other is bonded to CO. Therefore, the electron density on N is reduced by these electron-withdrawing groups, and an acidic atmosphere is exhibited.
It is considered that the color developing property of opening the lactone portion of various dye precursors is developed.

Regarding the image storability, the N-formamide group has a relatively large polarity and therefore has a low solubility in oil, a plasticizer and the like. Therefore, it is not eluted even when exposed to these, and as a result, image disappearance due to dissociation with the dye does not occur. Further, the carbonylsulfonamide group also has a property of being hardly dissolved in various solvents. Only when these two functional groups are present at the same time, a very excellent image storability is obtained synergistically.

The following compounds are exemplified as specific examples of the compound of the general formula (1) used in the present invention, but the invention is not limited thereto.

[0012]

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[0013]

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[Chemical 6]

[0014]

[Chemical 7]

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION General formula (1) used in the present invention
To obtain the compound represented by, for example, first, benzenesulfonamide and nitrobenzoyl chloride are heated under reflux in pyridine to obtain a coupling product. Then, a hydrogenation reaction is performed to synthesize an amino compound. This may be dissolved in formic acid, acetic anhydride may be added dropwise thereto, and the mixture may be heated and stirred at 50 ° C. for reaction.

To manufacture the thermosensitive recording medium of the present invention, various conventionally known manufacturing methods can be used. Specifically, it can be produced by the following method. That is,
The N-formamide compound is singly or mixed, and the dye precursor and the sensitizer are atomized by a pulverizer such as a ball mill, an attritor and a sand grinder or an emulsifier,
Various fillers and various additives are added, and dispersed in an aqueous solution of a water-soluble binder to form a coating. The coating is applied to an arbitrary support with an air knife coater, a blade coater, a roll coater, or any other coater to form a thermosensitive recording medium. Is obtained.

As the dye precursor used in the heat-sensitive recording material of the present invention, conventionally known dye precursors can be used and are not particularly limited. The dye precursor is illustrated below. These dye precursors may be used alone or in combination of two or more.

3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide (also known as CVL),
3-Diethylamino-6-methyl-7-anilinofluorane (ODB), 3-dibutylamino-6-methyl-7
-Anilinofluorane (ODB-2), 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane (S-205), 3-diethylamino-7
-M-trifluoromethylanilinofluorane (Bla
ck-100), 3-dibutylamino-7-o-chloroanilinofluorane (TH-107), 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-aminofluorane (PSD- 150), 3-diethylamino-7-anilinofluorane (Green-2), 3,
3-bis (4-dimethylaminophenyl) phthalide (M
GL), tris [4- (dimethylamino) phenyl] methane (LCV), 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide (indolyl red), 3-cyclohexylamino-6. -Chlorofluorane (OR-55), 3,3-bis [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide ( NI
R-Black), 1,1,5,5-tetrakis (p-
Dimethylaminophenyl) -3-methoxy-1,4-pentadiene, 1,1,5,5-tetrakis (p-dimethylaminophenyl) -3- (p-dimethylaminophenyl) -1,4-pentadiene.

In the present invention, the compound of the general formula (1) may be used in combination with one or more known conventionally used color developers. Examples of the color developer are shown below,
It is not limited to these.

Bisphenols such as 2,2-bis- (4-hydroxyphenyl) propane, 1,7-di (4-hydroxyphenylthio) -3,5-dioxaheptane and 4,4'-cyclohexylidenediphenol. Kind, 4-
4-hydroxybenzoic acid esters such as benzyl hydroxybenzoate, ethyl 4-hydroxybenzoate, n-propyl 4-hydroxybenzoate, isopropyl 4-hydroxybenzoate and butyl 4-hydroxybenzoate, 4
Dimethyl hydroxyphthalate, diisopropyl 4-hydroxyphthalate, dibenzyl 4-hydroxyphthalate, dihexyl 4-hydroxyphthalate, etc. 4-hydroxyphthalic acid diesters, phthalic acid monobenzyl ester, phthalic acid monocyclohexyl ester, phthalic acid Phthalic acid monoesters such as monophenyl ester and phthalic acid monomethylphenyl ester, bis- (4-
Hydroxy-3-tert-butyl-6-methylphenyl) sulfide, bis- (4-hydroxy-2,5-dimethylphenyl) sulfide, bis- (4-hydroxy-2-methyl-5-ethylphenyl) sulfide and the like. 4-hydroxyphenyl aryl sulfones such as bis-hydroxyphenyl sulfides, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-n-propoxydiphenyl sulfone 4-hydroxyphenylbenzenesulfonate, 4-hydroxyphenyl-p-tolylsulfonate, 4-hydroxyphenyl-p-chlorobenzenesulfonate, etc.
Hydroxyphenylarylsulfonates, 1,3-
Di [2- (4-hydroxyphenyl) -2-propyl]
1, such as benzene and 1,3-di [2- (4-hydroxy-3-alkylphenyl) -2-propyl] benzene
3-di [2- (hydroxyphenyl) -2-propyl]
Benzene, benzyl 4-hydroxybenzoyloxybenzoate, methyl 4-hydroxybenzoyloxybenzoate, ethyl 4-hydroxybenzoyloxybenzoate, n-propyl 4-hydroxybenzoyloxybenzoate, isopropyl 4-hydroxybenzoyloxybenzoate, 4-Hydroxybenzoyloxybenzoic acid esters such as butyl 4-hydroxybenzoyloxybenzoate, bis- (3-tert-butyl-4-hydroxy-6-methylphenyl) sulfone, bis- (3-ethyl-4-hydroxy) Phenyl) sulfone, bis- (3-
Propyl-4-hydroxyphenyl) sulfone, bis-
(3-isopropyl-4-hydroxyphenyl) sulfone, bis- (3-ethyl-4-hydroxyphenyl) sulfone, bis- (4-hydroxyphenyl) sulfone,
Bisphenol sulfones such as 2-hydroxyphenyl-4′-hydroxyphenyl sulfone, bis- (3-chloro-4-hydroxyphenyl) sulfone and bis- (3-bromo-4-hydroxyphenyl) sulfone, p
Phenol such as -tert-butylphenol, p-phenylphenol, p-benzylphenol, 1-naphthol, 2-naphthol, benzoic acid, p-tert
-Butylbenzoic acid, trichlorobenzoic acid, 3-sec-
Aromatic such as butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, 3,5-dimethyl-4-hydroxybenzoic acid, terephthalic acid, salicylic acid, 3-isopropylsalicylic acid, and 3-tert-butylsalicylic acid Metal salts of carboxylic acids.

In a heat-sensitive recording medium containing a dye precursor and a color developer as a color-forming component, a sensitizer is usually used to enhance the color-forming sensitivity. Sensitizer is information paper (Paper Industry Times, 1
987), non-impact printing (CMC,
1986) and various patent publications can be used. The following compounds can be illustrated as specific examples, but the compounds are not limited thereto, and two or more kinds of these may be used.

Stearic acid, zinc stearate, aluminum stearate, calcium stearate, zinc palmitate, stearic acid amide, palmitic acid amide, oleic acid amide, behenic acid, zinc behenate, ethylenebisstearamide, coconut fatty acid amide, Montan wax, polyethylene wax, phenyl-α-naphthyl carbonate, di-p-tolyl carbonate, diphenyl carbonate, 4-biphenyl-p-tolyl ether, p-benzyl biphenyl, m-terphenyl,
Triphenylmethane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,2-bis (3-methylphenoxy) ethane,
1,2-bisphenoxyethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-bisphenoxybutane, 1,4-bisphenoxybutene, 2-naphthylbenzyl ether, 1,4-di Ethoxynaphthalene, 1,4
-Dimethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid methyl ester, 2-naphthoic acid phenyl ester,
benzyl p-benzyloxybenzoate, dibenzyl terephthalate, dimethyl terephthalate, 1,1-diphenylethanol, 1,1-diphenyl-2-propanol,
1,3-diphenoxy-2-propanol, p- (benzyloxy) benzyl alcohol, n-octadecylcarbamoyl-p-methoxycarbonylbenzene, n-octadecylcarbamoylbenzene.

In the present invention, various auxiliaries may be added in order to improve the stability of recorded images. The following are examples, but the present invention is not limited thereto.

Metal salt of p-chlorobenzoic acid (Zn, C
a), p-nitrobenzoic acid metal salt (Zn, Ca), phthalic acid monobenzyl ester metal salt (Zn, Ca), 4,
4'-isopropylidene-bis (3-methyl-6-te
rt-butyl) phenol.

As the binder used in the heat-sensitive recording material of the present invention, those conventionally known in the field of heat-sensitive recording can be used and are not particularly limited. Examples of the binder are described below.

Completely saponified polyvinyl alcohol having a degree of polymerization of 2000 or less, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, other modified polyvinyl alcohol, hydroxy Ethyl cellulose, methyl cellulose,
Cellulose derivatives such as carboxymethylcellulose and acetylcellulose, casein, gelatin, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polymers and copolymers such as styrene, vinyl acetate, acrylamide and acrylate, polyamide Resins, silicone resins, petroleum resins, terpene resins, ketone resins, coumarone resins, and others can be mentioned. These natural and synthetic polymer substances can be used by dissolving them in water or an organic solvent such as alcohol, or can be used in a state of being emulsified or dispersed in a paste form in a medium such as water. Also, two or more of these can be used.

The filler used in the thermosensitive recording medium of the present invention includes clay, calcined clay, diatomaceous earth, talc, kaolin, calcium carbonate, basic magnesium carbonate, barium sulfate, barium carbonate, aluminum hydroxide, zinc oxide, silica , Magnesium hydroxide, titanium oxide, urea
Formalin resin, polystyrene resin, phenol resin,
Other natural or synthetic inorganic or organic fillers can be included, but are not limited to. Two or more of these can be used.

As additives, ultraviolet absorbers, defoamers,
Examples thereof include, but are not limited to, optical brighteners, waterproofing agents, and lubricants.

The amounts of the dye precursor and the developer used in the thermosensitive recording medium of the present invention, and the types and amounts of other various main components are as follows.
It is determined according to the required performance and recording suitability, and is not particularly limited, but usually 1 to 8 parts of the developer and 1 to 20 parts of the filler are used for 1 part of the dye precursor, and the binder is entirely used. 10 to 25% of the solid content is suitable.

As the support used in the thermal recording medium of the present invention, paper such as high quality paper, medium quality paper, coated paper, synthetic paper,
Examples thereof include plastic films, but are not limited thereto.

For the purpose of further improving the storage stability, an overcoat layer of a polymer substance or the like can be provided on the thermosensitive coloring layer. Further, for the purpose of enhancing the storage stability and sensitivity, an undercoat layer containing an organic filler or an inorganic filler may be provided between the color-forming layer and the support.

[0032]

EXAMPLES The present invention will be described in detail with reference to the following examples, which are synthetic examples of N-formamide compounds used in the present invention and production examples of heat-sensitive recording materials. Further, the reactants and other components used are shown as typical examples, and various modifications can be made within the scope of the present invention as described above.

-Synthesis of N-formamide compound- [Synthesis Example 1] Synthesis of N-benzenesulfonyl-4- (formamino) benzamide (A-01) 9.43 g of benzenesulfonamide and 40 ml of pyridine
Was dissolved. The solution was ice-cooled, and a solution of 11.36 g of p-nitrobenzoyl chloride dissolved in 40 ml of toluene was added dropwise under ice-cooling. The dropping was performed at 10 ° C. or lower.
After the dropping, the reaction solution was slowly returned to room temperature and further heated and refluxed for 5 hours. After completion of the reaction, the solvent was distilled off under reduced pressure, and the residue was extracted with ethyl acetate. The extract was washed with 1N hydrochloric acid, water, saturated aqueous sodium carbonate, water and brine in this order, and dried over anhydrous sodium sulfate. After removing the desiccant, the solvent was distilled off under reduced pressure, and the residue was recrystallized from a mixed solvent of methylene chloride and hexane to give N-benzenesulfonyl-4-nitrobenzamide.
Was obtained 4.48 g (yield 24%). This is ethanol 2
It was dissolved in 00 ml, 5% palladium carbon (0.64 g) was added, the system was replaced with hydrogen, and the mixture was reacted at room temperature for 5 hours. Palladium carbon was removed by filtration through Celite, and the solvent was distilled off under reduced pressure to obtain 3.60 g (yield 89%) of N-benzenesulfonyl-4-aminobenzamide. Furthermore, this is formic acid 10
It was dissolved in 0 ml, the solution was heated to 50 ° C., and 30 ml of acetic anhydride was added dropwise under the same temperature. After stirring for 1 hour as it was, the reaction solution was concentrated under reduced pressure. Precipitation occurred when ice water was added, and this was collected by filtration and recrystallized from a mixed solvent of acetone-hexane to give a white solid N-benzenesulfonyl-4-.
(Formamino) benzamide (A-01) was added to 2.73.
g (yield 70%) was obtained. The melting point is 190-191 ° C.

<IR spectrum> (KBr tablet method, cm ^-1 ) 3356,3284,3179,3059,1702,1675,160
9,1590,1522,1510,1446,1397,1326,1311,1240,1197,116
1,1056,892,845,758,720,694 < ¹ H-NMR spectrum> (300MHz, DMSO-d ₆ , δ / ppm, TMS) 12.46 (bs, 1H, SO ₂ NHC
O), 10.56 (s, 0.8H, NHCHO), 10.48 (d, 0.2H, J = 11Hz, NHCHO),
8.98 (d, 0.2H, J = 11Hz, NHCHO), 8.36 (s, 0.8H, NHCHO), 8.03
(d, 2H, J = 7Hz, Ar), 7.89 (d, 1.6H, J = 8Hz, Ar), 7.75-7.61 (m,
5H, Ar), 7.30 (d, 0.4H, J = 8Hz, Ar) < ¹³ C-NMR spectrum> (75MHz, DMSO-d ₆ , δ / ppm, TMS) 164.86, 162.84, 160.47,
142.78,139.77,133.85,130.45,130.05,129.33,127.88,1
26.24,118.68,116.42 <MS spectrum> (FAB-MS (M / Z)) 305 (M + H) ⁺

[Synthesis Example 2] Synthesis of N-[(4-methylbenzene) sulfonyl] -4 '-(formamino) benzamide (A-04) The same synthesis method as in Synthesis Example 1 was carried out. However, 4-toluenesulfonamide 10.
Using 0 g, 9.53 g (yield 51%) of the coupling product was obtained. Of this, 8.00 g was used to carry out a hydrogenation reaction to obtain 7.13 g (yield 98%) of a reduced product. Further, 6.00 g of the mixture was subjected to N-formylation reaction to give a pale yellow solid N-[(4-methylbenzene) sulfonyl] -4 '-(formamino) benzamide (A-
04) was obtained (4.55 g, yield 69%). Melting point is 143
It is -147 degreeC.

<IR spectrum> (KBr tablet method, cm ^-1 ) 3329,3093,2858,1671,1597,1530,145
7,1413,1343,1321,1249,1159,1068,839,661,562 < ¹ H-NMR spectrum> (300MHz, DMSO-d ₆ , δ / ppm, TMS) 12.27 (bs, 1H, SO ₂ NHC
O), 10.47 (s, 0.8H, NHCHO), 10.44 (d, 0.2H, J = 11Hz, NHCHO),
8.95 (d, 0.2H, J = 11Hz, NHCHO), 8.33 (s, 0.8H, NHCHO), 7.90
(d, 2H, J = 8Hz, Ar), 7.86 (d, 2H, J = 9Hz, Ar), 7.67 (d, 1.6H, J =
9Hz, Ar), 7.40 (d, 2H, J = 8Hz, Ar), 7.26 (d, 0.4H, J = 9Hz, Ar),
2.40 (s, 3H, Me) < ¹³ C-NMR spectrum> (75MHz, DMSO-d ₆ , δ / ppm, TMS) 164.86, 162.84, 160.47,
142.78,139.77,133.85,130.45,130.05,129.33,127.88,1
26.24,118.68,116.42 <MS spectrum> (FAB-MS (M / Z)) 305 (M + H) ⁺

[Synthesis Example 3] Synthesis of N-[(4-chlorobenzene) sulfonyl] -4 '-(formamino) benzamide (A-06) The same synthesis method as in Synthesis Example 1 was carried out. However, using 13.41 g of 4-chlorobenzenesulfonamide instead of benzenesulfonamide, the coupling product was converted to 19.3 g.
0 g (yield 82%) was obtained. A hydrogenation reaction was performed using 17.01 g of this to obtain 15.31 g (yield 99%) of a reduced product. Furthermore, using 12.88 g of that, N-
A formylation reaction was performed to obtain 8.73 g (yield 62%) of a pale yellow solid N-[(4-chlorobenzene) sulfonyl] -4 '-(formamino) benzamide (A-06). The melting point is 150-151 ° C.

<IR spectrum> (KBr tablet method, cm ^-1 ) 3610,3496,3099,3048,1681,1667,160
7,1546,1476,1463,1397,1344,1267,1160,1086,1078,84
9,827,766,561 < ¹ H-NMR spectrum> (300MHz, DMSO-d ₆ , δ / ppm, TMS) 12.50 (bs, 1H, SO ₂ NHC
O), 10.53 (s, 0.75H, NHCHO), 10.45 (d, 0.25H, J = 11Hz, NHCH
O), 8.95 (d, 0.25H, J = 10Hz, NHCHO), 8.33 (s, 0.75H, NHCHO),
7.98 (d, 2H, J = 9Hz, Ar), 7.87 (d, 1.5H, J = 9Hz, Ar), 7.70 (d, 2
H, J = 9Hz, Ar), 7.67 (d, 2H, J = 9Hz, Ar), 7.27 (d, 0.5H, J = 8.5H
z, Ar) < ¹³ C-NMR spectrum> (75 MHz, DMSO-d ₆ , δ / ppm, TMS) 164.96, 162.83, 160.46,
143.40,142.85,138.82,138.56,130.08,129.91,129.51,1
26.08,118.67,116.41 <MS spectrum> (FAB-MS (M / Z)) 339 (M + H) ⁺ , 341 (M + H + 2) ⁺

[Synthesis Example 4] Synthesis of N-[(4-formanilino) sulfonyl] -benzamide (A-10) The same synthesis method as in Synthesis Example 1 was carried out. However, starting from 26.28 g of 4-nitrobenzenesulfonamide instead of benzenesulfonamide and 17.4 ml of benzoyl chloride instead of 4-nitrobenzoyl chloride, 37.43 g (94% yield) of a coupling product was obtained. . A hydrogenation reaction was carried out using 7.66 g of this to obtain 6.98 g (yield 99%) of a reduced product. Furthermore, 6.
N-formylation reaction was carried out using 70 g to give a white solid N.
5.40 g (yield 74%) of-[(4-formanilino) sulfonyl] -benzamide (A-10) was obtained. The melting point is 203-205 ° C.

<IR spectrum> (KBr tablet method, cm ^-1 ) 3308, 3267, 3111, 3059, 1702, 1678, 159
2,1537,1498,1470,1402,1354,1273,1256,1163,1087,89
3,835,714,647,567 < ¹ H-NMR spectrum> (300MHz, DMSO-d ₆ , δ / ppm, TMS) 12.48 (bs, 1H, SO ₂ NHC
O), 10.67 (s, 0.8H, NHCHO), 10.57 (d, 0.2H, J = 10Hz, NHCHO),
8.98 (d, 0.2H, J = 10Hz, NHCHO), 8.38 (s, 0.8H, NHCHO), 7.95
(d, 2H, J = 9Hz, Ar), 7.87 (d, 1.6H, J = 9Hz, Ar), 7.84 (d, 2H, J =
9Hz, Ar), 7.64 (t, 1H, J = 8Hz, Ar), 7.50 (d, 2H, J = 9Hz, Ar), 7.
45 (d, 0.4H, J = 9Hz, Ar) <13 C-NMR _{spectrum> (75MHz, DMSO-d 6} , δ / ppm, TMS) 165.58,162.92,160.58,
142.88,133.53,133.45,131.69,129.85,129.67,128.79,1
28.59,119.00,116.75 <MS spectrum> (FAB-MS (M / Z)) 305 (M + H) ⁺

[Synthesis Example 5] N-[(4-formanilino) sulfonyl] -4'-methylbenzamide (A-1)
Synthesis of 3) The synthesis was performed in the same manner as in Synthesis Example 1. However, starting from 10.11 g of 4-nitrobenzenesulfonamide instead of benzenesulfonamide and 8.02 ml of 4-toluoyl chloride instead of 4-nitrobenzoyl chloride,
12.53 g (yield 78%) of the coupling product was obtained. Of this, 10.50 g was used for hydrogenation reaction to obtain 8.83 g (yield 95%) of a reduced product. Further, N-formylation reaction is carried out using 8.00 g of the above,
White solid N-[(4-formanilino) sulfonyl]-
5.88 g of 4'-methylbenzamide (A-13)
(Yield 67%) was obtained. The melting point is 148-149 ° C.

<IR spectrum> (KBr tablet method, cm ^-1 ) 3532,3263,3166,3113,1690,1680,161
1,1590,1492,1463,1452,1352,1339,1258,1161,1087,89
4,829,749,654,641,566 < ¹ H-NMR spectrum> (300MHz, DMSO-d ₆ , δ / ppm, TMS) 12.37 (bs, 1H, SO ₂ NHC
O), 10.65 (s, 0.8H, NHCHO), 10.51 (d, 0.2H, J = 10Hz, NHCHO),
8.96 (d, 0.2H, J = 11Hz, NHCHO), 8.35 (d, 0.8H, J = 1.2Hz, NHCH
O), 7.94 (d, 2H, J = 9Hz, Ar), 7.79 (d, 1.6H, J = 9Hz, Ar), 7.74
(d, 2H, J = 8Hz, Ar), 7.40 (d, 0.4H, J = 9Hz, Ar), 7.26 (d, 2H, J =
8 Hz, Ar), 2.33 (s, 3H, Me) < ¹³ C-NMR spectrum> (75 MHz, DMSO-d ₆ , δ / ppm, TMS) 165.38, 162.88, 160.58,
143.87,142.86,133.77,129.47,129.34,128.89,128.83,1
28.66,118.98,116.73,21.29 <MS spectrum> (FAB-MS (M / Z)) 319 (M + H) ⁺

Synthesis Example 6 N-[(4-formanilino) sulfonyl] -4'-chlorobenzamide (A-1)
Synthesis of 5) The synthesis was performed in the same manner as in Synthesis Example 1. However, starting from 10.11 g (50 mmol) of 4-nitrobenzenesulfonamide instead of benzenesulfonamide and from 7.63 ml (60 mmol) of p-chlorobenzoyl chloride instead of 4-nitrobenzoyl chloride, the coupling product was prepared as 15.15. 66 g (yield 92%) was obtained. Of these,
A hydrogenation reaction was carried out using 10.40 g to obtain 8.39 g (yield 90%) of a reduced product. Furthermore, it is 7.50
N-formylation reaction was carried out using g to obtain a white solid N-
4.86 g (yield 60%) of [(4-formanilino) sulfonyl] -4'-chlorobenzamide (A-15).
Obtained. The melting point is 159-161 ° C.

<IR spectrum> (KBr tablet method, cm ^-1 ) 3464, 3264, 3186, 3112, 1698, 1677, 159
0,1493,1466,1405,1364,1339,1258,1162,1087,893,840,
828,751,694,648,567 < ¹ H-NMR spectrum> (300MHz, DMSO-d ₆ , δ / ppm, TMS) 12.58 (bs, 1H, SO ₂ NHC
O), 10.65 (s, 0.75H, NHCHO), 10.56 (d, 0.25H, J = 10Hz, NHCH
O), 8.97 (d, 0.25H, J = 10Hz, NHCHO), 8.36 (s, 0.75H, NHCHO),
7.97 (d, 1.6H, J = 8Hz, Ar), 7.87 (d, 2H, J = 8Hz, Ar), 7.79 (d, 2
H, J = 8Hz, Ar), 7.53 (d, 2H, J = 8Hz, Ar), 7.43 (d, 0.4H, J = 8Hz,
Ar) < ¹³ C-NMR spectrum> (75 MHz, DMSO-d ₆ , δ / ppm, TMS) 164.68, 162.94, 160.61,
142.98,138.46,138.42,133.55,130.57,129.93,129.56,1
28.95,119.06,116.79 <MS spectrum> (FAB-MS (M / Z)) 339 (M + H) ⁺ , 341 (M + H + 2) ⁺

-Production of Thermal Recording Material-Examples 1 to 6 Thermal recording materials comprising the following compositions were prepared. That is, first, a dye dispersion (solution A) and a developer dispersion (solution B) having the following composition were each ground by a sand grinder to an average particle diameter of 1 μm. (Liquid A: Dye dispersion) 3-N, N-diethylamino-6-methyl-7-anilinofluorane 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts (solution B: color development) Agent dispersion) Compound of the present invention (see Tables 1 and 2) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts Then, dispersions A and B and kaolin clay in the following proportions. To prepare a heat-sensitive paint. Solution A: Dye dispersion 9.2 parts Solution B: developer dispersion 36.0 parts Kaolin clay (50% dispersion) 12.0 parts Amount of this heat-sensitive paint applied to one side of a 50 g / m ² base paper 6.
The sheet was coated and dried so as to have a thickness of 0 to 6.5 g / m ² , and this sheet was treated with a super calender so that the smoothness became 500 to 600 seconds, thereby producing a thermosensitive recording medium.

[Comparative Examples 1 to 3] Examples 1 to 6 except that in the developer dispersion (liquid B), the following conventionally known developers were used in place of the compounds used in the present invention. A thermosensitive recording medium was prepared in the same manner. 2,2-bis-4- (hydroxyphenyl) propane
(B-01) 4-Hydroxy-4'-isopropoxydiphenyl sulfone (B-02) N-benzoylbenzenesulfonamide (B-03)

-Evaluation of Thermal Recording Material- [Coloring Method] The thermal recording material prepared was used for UBI printer 2
01 (manufactured by UBI) with an applied energy of 450 mj / mm
^{In 2} , recording was performed on the produced thermosensitive recording medium. Next, the image density of the recording portion and the blank portion was measured using a Macbeth densitometer (RD-9).
14. An amber filter was used. Hereinafter, the concentration measurement was performed under these conditions. ). Using this as a test sample, the following test was performed. [Plasticizer resistance test]: A test sample was brought into contact with a vinyl chloride film (DIALAP 300G manufactured by Mitsubishi Plastics Co., Ltd.) and left at 40 ° C. for 24 hours, and the image residual density was measured with a Macbeth densitometer. [Oil resistance test]: The test sample was dipped in salad oil for 1 hour, wiped off the oil, and allowed to stand at room temperature for 24 hours, and the image residual density was measured with a Macbeth densitometer. [Heat-resistant ground color test on blank area]: The test sample was left at 100 ° C. for 30 minutes, and the density on the blank area was measured with a Macbeth densitometer. Table 1 shows the results of the image storability test of the image recording part and the heat resistant background color test of the blank part.

[0048]

[Table 1]

As is clear from these results, Examples 1 to 6 in which the compound of the present invention was used as the color developing agent had a better image storability than Comparative Examples 1 and 2 in which the conventional phenol type color developing agent was used. Has improved significantly. Further, as compared with Comparative Example 3 in which the carbonylsulfonamide compound was used as the color developer, the color density and the image storability were significantly improved, and N in the molecule was improved.
-The effect of having a formamide group and a carbonylsulfonamide group at the same time is remarkably exhibited. In addition, the compounds of the invention have good heat resistant background color results.

[0050]

The compound having an N-formamide group and a carbonylsulfonamide group used in the present invention is
The N-formamide structure and the carbonylsulfonamide structure provide sufficient ability to develop the dye precursor. A thermosensitive recording medium using the compound as a color developer is also very excellent in image storability in the recording area and heat-resistant background color stability in the blank area, and is extremely useful.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hidetoshi Yoshioka 5-21-1 Oji, Kita-ku, Tokyo Inside Central Research Institute, Nippon Paper Industries Co., Ltd.

Claims (1)

[Claims] 1. A thermosensitive recording medium having a thermosensitive color developing layer comprising a colorless or light-colored dye precursor and a developer which reacts when heated to develop the color of the dye precursor, wherein the developer has the following general formula: N-formamide group (-NHC) represented by (1)
HO) and carbonyl sulfonamide group (-SO ₂ NHC
A thermal recording material, which is a compound having O-). Embedded image (However, _one of A ₁ and A ₂ is an N-formamide group and the other is a hydrogen atom. R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an acyl group, Represents an alkoxycarbonyl group or a substituted or unsubstituted aryl group.)