JPH05169832A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance the oil resistance and plasticizer resistance of a recording image, in a thermal recording material having a thermal color forming layer containing a dye precursor and a developer reacting with the precursor under heating to develop a color, by using a compound represented by a specific chemical formula as the developer. CONSTITUTION:As the coupler contained in the thermal color forming layer of a thermal recording material, at least one kind of a compound represented by chemical formula (wherein R1 is one kind of an aromatic group substituted or non-substituted with at least one member selected from a lower alkyl group and a halogen atom, R2 and R3 are respectively independently a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group or a halogen atom and M is an (n) valent metal atom, for example, zinc, aluminum, magnesium or calcium) is used. This compound has no phenolic hydroxyl group but has strong color developing capacity to a basic leuco dye.

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-developed image is formed by heating, and more particularly to a heat-sensitive recording material which does not lose a color-developed image with time and is excellent in storage stability. More specifically, the present invention has good long-term storage stability of the recording, and moisture resistance of the recorded image, and environmental resistance such as heat resistance, and oil resistance,
And excellent in plastic resistance, image recording paper, facsimile paper, cash dispenser paper, ticket, commuter pass,
The present invention relates to a thermal recording material useful for labels such as POS labels, cards such as prepaid cards and tickets.

[0002]

2. Description of the Related Art A thermal recording material is generally composed of a support such as paper, synthetic paper, or plastic film, on which a color-forming substance composed of an electron-donating leuco dye and an organic acid substance such as an electron-accepting phenolic compound. A thermosensitive coloring layer containing a color-developing substance as a main component is provided, and a recorded image can be obtained by reacting these coloring components with thermal energy. Such thermal recording materials are disclosed in Japanese Examined Patent Publication Nos. 43-4160 and 45-140.
It is disclosed in Japanese Patent No. 39 and Japanese Patent Publication No. 48-27736, and has been widely put into practical use.

In general, a thermosensitive recording medium is used for an output of a computer, a facsimile, an automatic ticket vending machine, a printer of a scientific measuring instrument, or a CRT medical measuring instrument because the recording device is compact, inexpensive and easy to maintain. Widely used in printers, etc. However, in a conventional so-called dye-type thermosensitive recording medium in which a thermosensitive coloring layer containing a color-developing dye substance, a color-developing substance and a binder as an active ingredient is coated on a support, the coloring reaction is reversible. It is known that a colored image is erased over time because it is a target. This decolorization is accelerated by exposure to light, high humidity and high temperature,
Further, the contact with the plasticizer, oil and the like causes the image to proceed rapidly, and the image is erased to an unreadable level.

With respect to the thermosensitive color developing layer which normally uses a coloring system containing a dye precursor mainly composed of a colorless or light-colored lactone ring compound, many techniques have been disclosed in order to suppress this decoloring phenomenon. For example, JP-A-60-78782,
JP-A-59-167292, JP-A-59-114409
No. 6, and JP-A-59-93387, a compound containing a phenolic antioxidant in a thermosensitive color-developing layer, and a hydrophobic pigment as shown in JP-A-56-146796. A protective layer containing a polymer compound emulsion or the like formed on a thermosensitive color developing layer, JP-A-58-1
No. 99189, a water-soluble polymer compound or a hydrophobic polymer compound emulsion is provided on the thermosensitive coloring layer as an intermediate layer between the support and the thermosensitive coloring layer, and the hydrophobic polymer compound is provided thereon. Those provided with a surface layer of an oil paint as a resin component, and JP-A-62-164579.
As seen in No. 3, there is known one containing an epoxy compound in a thermosensitive coloring layer.

The image obtained in the heat-sensitive color forming layer containing the above-mentioned phenolic antioxidant has slightly improved environmental resistance as compared with the image obtained in the absence thereof, but it has oil resistance (for example, Preservation rate of image density after a certain period of time when salad oil was brought into contact with the coloring surface, and plasticizer resistance (image after a certain period of time when a wrap film containing a plasticizer was brought into contact with the coloring surface) No particular improvement in the storage ratio of concentration) is observed. On the other hand, in the thermal recording medium provided with the protective layer or the surface layer as described above, the environmental resistance is slightly improved, but when it is contacted with an oil or fat substance or a plasticizer for a long time, the image Decolorization is an unavoidable problem. Regarding oil resistance, the image storability immediately after contact with oil and fat substances is improved,
The image disappears almost completely as the oily substance penetrates, and it cannot be said to be an essential solution to the above problem. Further, in those containing an epoxy compound, a relatively long time is required from the heating color development operation until the color image is stabilized, for example, applying salad oil to the color image immediately after color development, If a colored image is brought into contact with a plasticizer, a considerable part of the color image is erased.

[0006]

DISCLOSURE 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 a colored image, and therefore, long-term storage of the colored image. The present invention is intended to provide a heat-sensitive recording material having excellent properties. Further, the present invention is useful, for example, as a ticket for a thermal recording medium for an automatic ticket vending machine, and not only that, but also as a ticket such as a coupon ticket or a commuter ticket that requires long-term storage, or as a polyvinyl chloride film. Not only suitable for applications in which contact with plasticizers and / or oils and fats, such as labels for POS bar code systems attached to the packaging surface of packaged foods, but also for long-term storage, facsimile paper or word processor paper Further, the present invention aims to provide a thermal recording material that can be used as an image printer sheet for CRT.

[0007]

The inventors of the present invention have found that the storage stability-improving effects such as oil resistance and plasticizer resistance of a color-developed image are exhibited within a shortest possible time after formation of the color-developed image. , The improved thermosensitive coloring layer was examined, and as a result,
It was discovered that an aromatic carboxylic acid derivative having an arylsulfonylaminocarbonylamino group has excellent color-developing ability and high oil and plasticizer resistance, and thus the obtained color image has an excellent long-term storage stabilizing effect. Then, the present invention has been completed.

That is, the heat-sensitive recording material of the present invention is a sheet-like substrate, a colorless or light-colored dye precursor formed on at least one surface of the sheet-like substrate, and reacts with the dye precursor under heating. And a thermosensitive color developing layer containing a color developing agent for developing the color, and the color developing agent is represented by the following general formula (I):

[Chemical 2] (However, R ₁ represents a lower alkyl group, and a member selected from at least one member selected from a halogen atom, and an unsubstituted aromatic group; R ₂ and R ₃ represent Each independently represent one member selected from a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group and a halogen atom, and M
Represents an n-valent metal atom, and n represents an integer of 1 or more. ) At least one compound represented by

[0009]

The compound of the formula (I) used in the present invention is a colorless or light-colored basic leuco dye (dye precursor) and a color developer capable of reacting with this dye precursor under heating to develop a color. It acts as a developer in the image formation in the thermosensitive coloring layer utilizing the color reaction with the agent. That is, the compound of the formula (I) does not have a phenolic hydroxyl group, but has a strong developing ability with respect to a basic leuco dye. It is speculated that this is because the urea group in the compound of formula (I) is activated by the sulfonyl group adjacent to it. Further, it is understood that the images formed by the reaction of the compound of the formula (I) and the leuco dye exhibit high storage stability under various environments because of the synergistic effect of the allylsulfonylurea group and the carboxylic acid group. To be done.

In the formula (I), the metal atom represented by M is preferably zinc, aluminum, magnesium and calcium. Specific examples of compounds of formula (I) useful in the present invention include the following chemical formula:

[Chemical 3] Compounds No. 1 to No. 9 represented by and the metal salts thereof can be used. In addition, these compounds may be used by dispersing them into metal salts,
This may be dispersed and used in the coexistence of a metal compound such as zinc oxide or calcium carbonate. 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 can be synthesized, for example, by the following reaction (1) or (2). Reaction (1): R ₁ —SO ₂ —NCO + R ₂ —NH—R ₃ → compound of formula (1) (ester) → hydrolysis → compound of formula (1) (acid) reaction (2): R ₁ -SO _{2 -NNCOO-R + R 2 -NH} -R 3 → base → compound of formula (1) (ester) → hydrolysis → compound of formula (1) (acid) was prepared in which in the above formula, R _1, R _2, and R ₃ has the same definition as defined above, and R represents a member selected from a lower alkyl group and an aryl group. ]

In the present invention, the leuco dye used as the dye precursor can be selected from conventionally known ones such as triphenylmethane type compounds, fluorane type compounds and diphenylmethane type compounds. Examples of these dye precursors include 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-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-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- (p-chloroanilino ) One or more selected from fluoran and the like can be used.

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, as long as the desired effect is not impaired. 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) and the like.

Further, in the present invention, the heat-sensitive coloring layer may contain a heat-fusible substance (so-called sensitizer). As such a sensitizer, a heat-fusible organic compound having a melting point of 50 to 150 ° C. is used, and they are, for example, 1-
Hydroxy-2-naphthoic acid phenyl ester (JP-A-57-191089), p-benzylbiphenyl (JP-A-60-82382), benzylnaphthyl ether (JP-A-58-87094), dibenzyl terephthalate (special JP-A-58-98285), benzyl p-benzyloxybenzoate (JP-A-57-201691),
Diphenyl carbonate, ditolyl carbonate (Japanese Patent Laid-Open No. 58-1364)
89), m-terphenyl (JP-A-57-89994).
No.), 1,2-bis (m-tolyloxy) ethane (JP-A-60-56588), 1,5-bis (p-methoxyphenoxy) -3-oxapentane (JP-A-62-18).
1183), oxalic acid diesters (JP-A-64-1)
583), 1,4-bis (p-tolyloxy) -benzene (JP-A-2-153787), and the like.

The heat-sensitive color developing layer of the present invention may further contain a hindered phenol compound or an ultraviolet absorber. They are, for example, JP-A-57-151394.
No. 58-160191 and 58-690.
96, JP-A-59-2884, JP-A-59-951
90, JP-A-60-22288, and JP-A-60-25.
5485, JP-A 61-44686, JP-A 62-
169683, JP-A-63-17081, JP-A-1
No. 249385 and Japanese Patent Application No. 2-266645, and the like, and specifically,
For example, 1,1,3-tris (3'-cyclohexyl-
4'-hydroxyphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-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'-diphenylacrylate, 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 contains the dye precursor and the developer compound of the above formula (I) of the present invention, but preferably further contains the sensitizer. Further, the heat-sensitive coloring layer, as described above, if necessary, a conventionally known phenol-based or organic acid-based developer,
Antioxidants, UV absorbers, or waxes can be included. Furthermore, it is preferable that the thermosensitive coloring layer contains organic or inorganic pigments. The thermosensitive coloring layer contains a binder for joining these components and fixing them to the support.

In the present invention, the content of the dye precursor in the thermosensitive coloring layer is generally preferably 5 to 20% by weight based on the dry weight of the thermosensitive coloring layer, and the content of the dye represented by the formula (I) of the present invention. Generally, the content of the colorant compound is preferably 10 to 50% by weight based on the dry weight of the thermosensitive coloring layer.
When the content of the color developing agent compound of the formula (I) is less than 10% by weight, the resulting thermosensitive color developing layer has insufficient color developing ability,
Even if it is used in a large amount exceeding 50% by weight, the color developing ability is saturated and no particular improvement is observed, which may be economically disadvantageous.

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

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. Examples thereof include inorganic fine powder such as silica and silica, and organic fine powder such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin.

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

As the binder, polyvinyl alcohol 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 copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, polyacrylamide, alginic acid Water-soluble polymer materials such as soda, gelatin, and casein, as well as polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate , Ethylene / vinyl acetate copolymer, and styrene /
Each latex such as butadiene / acrylic copolymer can be used.

The sheet-like substrate used in the heat-sensitive recording material of the present invention is selected from paper, coated paper having a surface coated with a pigment, latex, etc., laminated paper, synthetic paper made from polyolefin resin, plastic film and the like. be able to.

At least one surface of such a sheet-like substrate
Apply a coating solution containing the mixture of the above required components on top and dry.
Dry to produce a thermosensitive recording medium. The coating amount of this coating solution is
When the coating liquid layer is dried, 1 to 15 g / m²To become
Is preferred and 2 to 10 g / m ²More like to be
Yes.

In the thermosensitive recording medium of the present invention, a protective layer and / or a coating layer such as a printing layer may be further formed on the thermosensitive coloring layer, or between the support and the thermosensitive coloring layer. May be provided with an intermediate layer.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following examples. In these examples, unless otherwise specified,
"Parts" and "%" represent "parts by weight" and "% by weight", respectively.

Synthesis Example 1 o- (p-toluenesulfonyl)
Aminocarbonylamino) benzoic acid synthetic dropping funnel, and a three-necked flask equipped with a thermometer,
29.0 g of o-aminobenzoic acid methyl ester was added and this was dissolved in 300 ml of toluene. While vigorously stirring this solution with a magnetic stirrer, 39.4 g of toluenesulfonyl isocyanate was added dropwise from a dropping funnel. Then, an exothermic reaction occurred with dropping and a white solid was deposited, but when this mixed solution was stirred at 90 ° C. for another hour, a uniform solution was formed. 58.2 was obtained by adding an appropriate amount of n-hexane and recrystallizing.
g of o- (p-toluenesulfonylaminocarbonylamino) benzoic acid methyl ester was obtained as white crystals. Its melting point was 125 ° C.

This white solid was mixed with 3% ethanol containing 10% water.
Dissolve 27 g of caustic potash in 00 ml to 90
The above compound was hydrolyzed by heating at ° C for 1 hour. Next, the obtained solution was acidified with hydrochloric acid and then poured into a large amount of water to obtain a white solid. Its melting point was 168 ° C. By NMR measurement, mass spectrometry and IR measurement, the obtained compound was identified as the target compound.

The results of NMR measurement (in heavy acetone) are as follows. δ = 2.42 (s, 3H), 7.12 (t, 1)
H), 7.42 (d, 2H), 7.57 (t, 1H),
8.00 (d, 2H), 8.05 (d, 1H), 8.3
9 (d, 1H) and other peaks that are thought to be due to the N—H bond appeared near δ = 10.8.

The following characteristic absorption was confirmed by IR measurement (KBr tablet method). 1720 cm ^-1 (derived from a carboxyl group) 1680 cm ^-1 (derived from the carbonyl group of the urea group) 1345cm ^-1, (derived from the sulfonyl group) 1160 cm ^-1

Synthesis Example 2 p- (p-toluenesulfonyl
Aminocarbonylamino) benzoic acid synthetic dropping funnel, and a three-necked flask equipped with a thermometer,
32.3 g of p-aminobenzoic acid ethyl ester was added, and this was dissolved in 300 ml of toluene. While vigorously stirring this solution with a magnetic stirrer, 39.4 g of toluenesulfonyl isocyanate was added dropwise from a dropping funnel. Then, an exothermic reaction occurred with dropping, and a large amount of white solid was deposited. 90 ℃ this mixture
After further stirring for 1 hour, the mixture was cooled. The obtained reaction solution was filtered to remove the solid, and 70.1 g of white crystals of p- (p-toluenesulfonylaminocarbonylamino) benzoic acid ethyl ester were obtained. Its melting point was 176 ° C.

This white solid was mixed with 10% hydrous ethanol 3
Dissolve 27 g of caustic potash in 00 ml to 90
The above compound was hydrolyzed by heating at 0 ° C for 1 hour.
Next, the obtained solution was acidified with hydrochloric acid and then poured into a large amount of water to obtain a white solid. Its melting point is 20
It was 0 ° C. By NMR measurement, mass spectrometry and IR measurement, the obtained compound was identified as the target compound.

The results of NMR measurement (in heavy acetone) are as follows. δ = 2.45 (s, 3H), 7.45 (d, 2)
H), 7.60 (d, 2H), 8.00 (d, 4H),
Other peaks that are thought to be due to N—H bonds are δ =
Appeared around 8.8.

The following characteristic absorption was confirmed by IR measurement (KBr tablet method). 1700 cm ^-1 (Stacking absorption of absorption derived from carboxyl group and absorption derived from carbonyl group of urea group) 1345 cm ^-1 , and 1160 cm ^-1 (derived from sulfonyl group)

Example 1 A thermosensitive recording paper was manufactured by the following procedure . The sand grinder to 20 6-methyl-7-anilinofluoran polyvinyl alcohol 10% solution 10 Water 70 The composition - Dispersion Preparation Ingredient Weight (parts) 3- (N-isopentyl -N- ethylamino) of A , Average particle size is 1
It was pulverized until it became less than μm.

Preparation of dispersion B Component weight (parts) o- (p-toluenesulfonyl-aminocarbonylamino) 10 Benzoic acid (Compound No. 1) Oxalic acid di-p-methylbenzyl ester 10 Polyvinyl alcohol 10% liquid 10 Water 70 The average particle size of the above composition was 1 using a sand grinder.
It was pulverized until it became less than μm.

Preparation of Pigmented Undercoat Paper 85 parts of calcined clay (trademark: Ansilex) in 320 parts of water
A styrene-butadiene copolymer emulsion (solid content 50%) 40 parts and a 10% aqueous solution of oxidized starch 50 parts were mixed with the resulting dispersion to obtain a coating liquid, and the basis weight was 48 g. / m on one side of the ^second base paper, the coating amount after drying was coated so as to 7.0 g / m ^2, was prepared pigment undercoat paper.

Formation of thermosensitive coloring layer To 50 parts of the above liquid A and 200 parts of liquid B, 30 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, 3
15 parts of 0% paraffin dispersion and 100 parts of 10% aqueous polyvinyl alcohol solution were mixed and stirred to prepare a coating solution. This coating solution was applied to one side of the pigment-undercoated paper so as to have a coating amount after drying of 5.0 g / m ² and dried to form a thermosensitive coloring layer to prepare a thermosensitive recording paper. The thermal recording paper obtained as described above was treated with a super calendar, and the surface smoothness was adjusted to 600 to 1000 seconds.

With respect to the sample thus obtained, the color was developed with an applied energy of 0.49 mj / dot using a dynamic color tester obtained by modifying a commercial thermal facsimile machine manufactured by Hitachi, Ltd. The density of the obtained color image was measured with a Macbeth reflection densitometer RD-914 (this is called the original density). Then make a predetermined test piece from this color-developed sample,
Salad oil or dioctyl terephthalate (representative plasticizer) is applied to this test piece within 30 minutes after color development, and after leaving at room temperature for 3 hours, excess oil or plasticizer is wiped off, and the residual image density is measured by a Macbeth reflection densitometer. And the image preservation ratio was calculated according to the following formula.

Image preservation ratio (%) = [(residual image density) / (original density)] × 100 Table 1 shows the test results.

Example 2 A thermal recording paper was manufactured in the same manner as in Example 1. However, in preparing the dispersion liquid B, p- was used instead of o- (p-toluenesulfonylaminocarbonylamino) benzoic acid.
(P-Toluenesulfonylaminocarbonylamino) benzoic acid (Compound No. 3) was used. The test results are shown in Table 1.

Example 3 A thermal recording paper was produced in the same manner as in Example 1. However, in the preparation of the dispersion liquid B, instead of o- (p-toluenesulfonylaminocarbonylamino) benzoic acid, o-
(O-Toluenesulfonylaminocarbonylamino) benzoic acid (Compound No. 7) was used. Also, oxalic acid dip-
Oxalic acid dibenzyl ester was used instead of methylbenzyl ester. The test results are shown in Table 1.

Example 4 A thermal recording paper was manufactured in the same manner as in Example 1. However, in the preparation of Dispersion A, 3- (N-isopentyl-N-
3- (N, N-Dibutylamino) -6-methyl-7-anilinofluorane was used instead of ethylamino) -6-methyl-7-anilinofluorane. The test results are shown in Table 1.

Example 5 A thermal recording paper was produced in the same manner as in Example 1. However, Dispersion C having the following composition was prepared, and this Dispersion C was used in place of Dispersion B in the formation of the thermosensitive color developing layer. Preparation of Dispersion C Component weight (parts) o- (p-Toluenesulfonyl-aminocarbonylamino) 10 Benzoic acid (Compound No. 1) Oxalic acid di-p-methylbenzyl ester 10 40% Zinc oxide dispersion 15 Polyvinyl alcohol 10% liquid 10 water 55 The above composition was pulverized using a sand grinder until the average particle size became 2 μm or less. The test results are shown in Table 1.

Example 6 A thermal recording paper was produced in the same manner as in Example 1. However, in the formation of the thermosensitive coloring layer, 40 parts of solution A and solution 12 of solution B were used.
40 parts of C liquid described in Example 5 was mixed with 0 parts, and further 40 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, 15 parts of 30% paraffin dispersion and 120 parts of 10% aqueous polyvinyl alcohol solution. , And 3 parts of a wetting aid (Dapro U99) were mixed and stirred to prepare a coating liquid.
This coating solution was applied to one side of a synthetic paper (trademark: YUPO HBG-75, manufactured by Oji Yuka Synthetic Paper Co., Ltd.) at a coating amount of 8.5 g after drying.
/ M ² to form a thermosensitive coloring layer by coating and drying.
A thermal recording paper was prepared. The test results are shown in Table 1.

Comparative Example 1 A thermal recording paper was manufactured in the same manner as in Example 1. However, in the preparation of the dispersion liquid B, 2,2 instead of o- (p-toluenesulfonylaminocarbonylamino) benzoic acid was used.
-Bis (4-hydroxyphenyl) propane (bisphenol A) was used. The test results are shown in Table 1.

[0046]

[Table 1]

As is clear from Table 1 above, the novel developer used in the present invention has much better oil resistance and plasticizer resistance than bisphenol A which is a representative of conventional developers. This is what is given to the color image.

[0048]

The heat-sensitive recording material of the present invention contains a compound having an N-arylsulfonylurea group and a carboxyl group in one molecule as a color developer in the heat-sensitive color forming layer thereof. Therefore, the thermosensitive coloring layer has good sensitivity,
Moreover, the color image formed on the thermosensitive color developing layer has excellent oil resistance and plasticizer resistance immediately after color development.

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[Procedure amendment]

[Submission date] February 5, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Many of the compounds of formula (I) as described above are
It is a novel compound that has not been reported so far and can be synthesized, for example, by the following reaction (1) or (2). Reaction _{(1): R 1 -SO 2} -NCO + R 2 -NH-R 3 → compound of formula (I) (ester) → hydrolysis → compound of formula (I) (acid) Reaction (2): R _{1 -SO 2 -N H COO-R +} R 2 -NH-R 3 → compound of formula (I) (ester) → hydrolysis → compound of formula (I) (acid) was prepared in which in the above formula, R _1, R ₂ and R ₃ are the same as defined above, and R represents a member selected from a lower alkyl group and an aryl group. ]

Claims (1)

[Claims] 1. A sheet-shaped substrate, a colorless or light-colored dye precursor which is formed on at least one surface of the sheet-shaped substrate, and a developer which reacts with the dye precursor under heating to develop a color. And a thermosensitive coloring layer containing the above-mentioned color developer, wherein the developer has the following general formula (I): (However, R ₁ represents one member selected from a lower alkyl group and an aromatic group which is substituted with at least one member selected from a halogen atom, and is not substituted,
R ₂ and R ₃ each independently represent one member selected from a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, and a halogen atom,
M represents an n-valent metal atom, and n represents an integer of 1 or more. ) A thermal recording material comprising at least one compound represented by