JP2679459B2 - Thermal recording medium - Google Patents

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 image is formed by heating, and more particularly to a heat-sensitive recording material which does not lose a once-colored image and is excellent in storage stability. More specifically, the long-term storability of the recorded image is good, and at the same time, the recorded image has excellent moisture resistance, environment resistance such as heat resistance, oil resistance, and plasticizer resistance.
Also, the whiteness is high, so 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 pass tickets.

[0002]

2. Description of the Related Art A thermal recording material is generally composed of a color-forming substance such as an electron-donating leuco dye and an organic acid substance such as an electron-accepting phenolic compound on a support such as paper, synthetic paper and plastic film. 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 a thermal recording material is disclosed in, for example, Japanese Examined Patent Publication No.
No. 60, Japanese Patent Publication No. 45-14039, and Japanese Patent Publication No. 48-
It is disclosed in Japanese Patent No. 27736 and is widely put into practical use.

Since the recording device of the thermal recording medium is compact, inexpensive and easy to maintain, the output of a computer, a facsimile, an automatic ticket vending machine, a printer for scientific measuring instruments, a printer for CRT medical measurement, etc. Widely used in. However, in a conventional so-called dye-type heat-sensitive recording material in which a heat-sensitive coloring layer containing a color-forming dye substance, a color-developing substance and a binder as an active ingredient is coated on a support, the coloring reaction is reversible. For this reason, it is known that a color image loses its color over time. This erasing phenomenon is due to light exposure,
The image is accelerated in a high-humidity and high-temperature atmosphere, and further progresses rapidly due to contact with a plasticizer and oil, and the image is erased to an unreadable level.

When a coloring system containing a dye precursor mainly containing a colorless or light-colored lactone ring compound is used,
Many techniques have been disclosed to suppress this decoloring phenomenon. For example, JP-A-60-78782 and JP-A-59
No. 167292, JP-A-59-114096, and JP-A-59-93387, in which a thermosensitive color-forming layer is blended with a phenolic antioxidant,
An emulsion using a hydrophobic polymer compound emulsion as disclosed in JP-A-56-146796 in a protective layer, or a highly water-soluble layer on a thermosensitive coloring layer as disclosed in JP-A-58-199189. A molecular compound or a hydrophobic polymer compound emulsion is provided as an intermediate layer, and a surface layer of an oil-based paint containing a hydrophobic polymer compound as a resin component is provided thereon, and further, JP-A-62-16457.
Those containing an epoxy compound as found in No. 9 are known.

In the thermosensitive coloring layer containing the above-mentioned phenolic antioxidant, the environment resistance is slightly improved as compared with the image in the case where it is not contained, but the oil resistance (for example, salad oil is used as a coloring surface). Of image density after a certain period of time when contacted with a), plasticizer resistance (preservation rate of image density after a certain period of time when a wrap film containing a plasticizer is brought into contact with the color surface), etc. No improvement can be recognized for. On the other hand, a thermal recording material provided with a protective layer and a surface layer has a considerably improved environmental resistance, but erasing is inevitable after long-term storage or use. Regarding the oil resistance, the image storability immediately after contact with oil is improved, but the image disappears almost completely as the oil permeates,
It is not 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, When it comes into contact with a plasticizer, a large part of the color image is erased.

[0006]

SUMMARY OF THE INVENTION The present invention solves these problems in the prior art and is a thermal recording material excellent in long-term storage stability of color images such as oil resistance, plasticizer resistance, moisture resistance, and heat resistance. Is to provide. INDUSTRIAL APPLICABILITY The present invention can be used not only as a heat-sensitive recording type ticket for an automatic ticket vending machine, but also for use on a number-of-times ticket or a commuter ticket that requires preservation and contact with plasticizers and fats and oils is inevitable. Suitable as a label for a POS bar code system that is attached to the packaging surface of food packed with vinyl chloride film, and also for long-term storage such as facsimile paper, word processor paper, and CRT.
The present invention aims to provide a thermal recording material that can also be used as an image printer paper.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have developed a thermosensitive color development in which the storage stability-improving effects such as oil resistance and plasticizer resistance of a color image are developed within the shortest possible time after color image formation. The layer modification method was investigated, and as a result, a group of N-arylsulfonyl (thio) urea derivatives having a specific chemical structure was
Having excellent color developing ability, further by combining this compound with an aziridine compound, it is possible to obtain a thermosensitive color forming layer having excellent oil and plasticizer resistance, and thus an excellent long-term storage stabilizing effect, and , These compounds are
It has been discovered that, even though it does not have an acidic functional group such as a phenolic hydroxyl group or a carboxyl group, it has the ability to strongly color when contacted with a colorless or light-colored basic leuco dye. The invention was completed.

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 thermosensitive color developing layer containing a colorless or light-colored dye precursor and a color developing agent that reacts under heating to develop a color, and the color developing agent has the following general formula (I):

Embedded image[However, in the formula (I), X represents an oxygen atom or a sulfur atom.
Represents, R₁Is an aromatic group having no substituent, and a low
Less selected from primary alkyl groups and halogen atoms
One selected from benzene ring groups substituted by 1 member
Represents a member, R _Two, R_ThreeIndependently of each other, hydrogen
Atom, alkyl group, aralkyl group, aryloxy group
Substituted alkyl group, aromatic group having no substituent,
And an alkyl group, an aryl group, an aralkyl group, an alkyl group.
Luoxy group, alkyloxycarbonyl group, aryl group
Xycarbonyl group, aralkyloxycarbonyl group,
Selected from reel sulfonyl group and halogen atom
Selected from aromatic groups substituted by at least one member
Represent a member. ] At least one compound represented by
It is characterized by the following.

In the heat-sensitive recording material of the present invention, the heat-sensitive color developing layer may further contain an organic compound having at least one aziridinyl group. The aziridinyl group has the following chemical formula (II):

Embedded image Is represented by

[0010]

The N-arylsulfonyl (thio) ureas of the formula (I) used in the present invention act as a developer. That is, the compound of formula (I) does not have an acidic functional group such as a phenolic hydroxyl group or a carboxyl group, but has a strong color developing ability for a basic leuco dye. It is understood that this is because the (thio) urea group in the compound of formula (I) is activated by the sulfonyl group adjacent to it.

Specific examples of the compound of formula (I) are as follows. N- (p-toluenesulfonyl) -N'-phenylurea (melting point 165 ° C), N- (p-toluenesulfonyl)-
N '-(p-methoxyphenyl) urea (melting point 155
C), N- (p-toluenesulfonyl) -N '-(o-
Trilyl) urea (melting point 148 ° C.), N- (p-toluenesulfonyl) -N ′-(m-tolyl) urea (melting point 184
C), N- (p-toluenesulfonyl) -N '-(p-tolyl) urea (melting point 149C), N- (p-toluenesulfonyl) -N'-(pn-butylphenyl) urea (melting point 177). C), N- (p-toluenesulfonyl)-
N ', N'-diphenylurea (melting point 159 ° C), N-
(P-toluenesulfonyl) -N '-(o-chlorophenyl) urea (melting point 180 ° C), N- (p-toluenesulfonyl) -N'-(m-chlorophenyl) urea (melting point 1
93 ° C.), N- (p-toluenesulfonyl) -N′-
(2,4-dichlorophenyl) urea, N- (p-toluenesulfonyl) -N'-methyl-N'-phenylurea (melting point 155 ° C), N- (p-toluenesulfonyl)-
N'-benzylurea (melting point 177 ° C), N- (p-toluenesulfonyl) -N '-(1-naphthyl) urea (melting point 124 ° C), N- (p-toluenesulfonyl) -N'-
(1- (2-methylnaphthyl)) urea, N- (benzenesulfonyl) -N′-phenylurea (melting point 153 ° C.),
N- (p-chlorobenzenesulfonyl) -N'-phenylurea, N- (o-toluenesulfonyl) -N'-phenylurea, N- (p-toluenesulfonyl) -N'-methylurea (melting point 172 ° C), N- (p-toluenesulfonyl) -N'-ethylurea (melting point 141 ° C), N- (p
-Toluenesulfonyl) -N '-(2-phenoxyethyl) urea (melting point 191 ° C), N, N'-bis (p-toluenesulfonyl) urea (melting point 155 ° C), N- (p-toluenesulfonyl) -N '-Phenylthiourea, N-
(P-toluenesulfonyl) -N '-(o-diphenyl) urea (melting point 148 ° C), N- (p-toluenesulfonyl) -N'-(p-ethoxycarbonylphenyl) urea. These compounds may be used alone or as a mixture of two or more thereof.

Many of the N-arylsulfonyl (thio) ureas of the formula (I) as described above are novel compounds which have not been reported so far, and their synthesis is carried out, for example, by the following reactions (1) to (4). Can be done by.

Embedded image

Examples of compounds having an aziridinyl group that can be used in the present invention are disclosed in Japanese Patent Application No. 2-23314.
Although it is described in No. 9, specific examples thereof include the following compounds. 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.

Examples of the leuco dye used as a dye precursor in the present invention include triphenylmethane type, fluorane type and diphenylmethane type compounds, which can be selected from conventionally known ones. 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-Np-toluidino) -6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-
7-anilinofluoran, 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 One or more selected from-(p-chloroanilino) fluorane 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 within a range that does not inhibit the desired effect. These conventional color developers are, 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-52-140483), bisphenol S, 4-hydroxy-4'-isopropyloxydiphenyl sulfone (JP-A-60-13852),
1,1-di (4-hydroxyphenyl) cyclohexane, 1,7-di (4-hydroxyphenylthio) -3,
5-dioxaheptane (JP-A-59-52694),
3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone (JP-A-60-208286) and the like.

Further, in the present invention, it is preferable to use a heat-fusible substance (so-called sensitizer) in combination. As the sensitizer, a heat-fusible organic compound having a melting point of 50-150 C is used,
Examples thereof include 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 (JP-A-58-98285)
No.), benzyl p-benzyloxybenzoate (Japanese Unexamined Patent Publication No.
7-201691), diphenyl carbonate, ditolyl carbonate (JP-A-58-136489), m-terphenyl (JP-A-57-89994), and 1,2-bis (m-tolyloxy) ethane (JP-A-5-89994). No. 60-56588),
1,5-bis (p-methoxyphenoxy) -3-oxapentane (JP-A-62-181183), oxalic acid diesters (JP-A-64-1583), 1,4-bis (p-tolyloxy) benzene (JP-A-2-15378
No. 3) and so on.

The thermosensitive coloring layer of the present invention may further contain a hindered phenol compound or an ultraviolet absorber. These are described, for example, in JP-A-57-151394, JP-A-58-160191, and JP-A-58-69096.
JP-A-59-28884, JP-A-59-95190
JP-A-60-22288, JP-A-60-2554
No. 85, JP-A-61-44686, JP-A-62-16
9683, JP-A-63-17081, JP-A-1-249385, and the like. Specific examples include 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'-
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 comprises (a) a dye precursor, a mixture of the compound of the above formula (I) of the present invention and a sensitizer, or (b) a dye precursor. It includes the compound of the above formula (I) of the present invention, a sensitizer, and an aziridine compound. In each case, the thermosensitive coloring layer may contain a conventionally known phenol-based or organic acid-based developer, antioxidant, ultraviolet absorber, or wax, if necessary. Further, it preferably contains organic or inorganic pigments. Further, the thermosensitive coloring layer contains a binder for fixing these components to the support.

The content of the above-mentioned 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 color developing agent of the formula (I) of the present invention is Generally, it is preferably 10 to 50% by weight.
When the content of the color developer is less than 10% by weight, the color developing ability is insufficient, and even when it exceeds 50% by weight, the color developing ability is saturated and no particular improvement is observed, which is economically disadvantageous. May be. When the thermosensitive coloring layer contains an aziridine compound, 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. A conventionally known phenolic or organic acid-based developer, and its content is preferably 5 to 40% by weight, and the content of the sensitizer is preferably 10 to 40% by weight. When waxes and white pigments are contained in the thermosensitive coloring layer, their contents are respectively 5 to 20% by weight and 10 to 5% by weight.
It is preferably 0% by weight, and the content of the binder is generally 5 to 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.
About the binder, polyvinyl alcohol of various molecular weights, starch and derivatives thereof, methoxycellulose, carboxymethylcellulose, methylcellulose,
Cellulose derivatives such as ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide /
Water-soluble polymers such as acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, and casein Materials and polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / Each latex such as a 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. On at least one surface of such a sheet-like substrate, a coating solution containing a mixture of the above-mentioned required components is applied and dried to produce a thermosensitive recording medium. The coating amount is preferably 1 to 15 g / m ² when the coating liquid layer is dried, and ² to 10 g.
/ M ² is particularly preferred.

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

[0025]

The present invention will be specifically described below with reference to examples. Unless otherwise specified, "part" and "%" represent "part by weight" and "% by weight", respectively.

[0026]Synthesis Example 1 N- (p-toluenesulfoni
) -N'-phenylurea A three-necked frass equipped with a dropping funnel, thermometer, and reflux.
Put 18.6g of aniline in 200 ml of torue
Dissolved in water. Magnetic stirrer for reaction solution
While stirring, add 42.0 g of toluene sulphate from the dropping funnel.
Honyl isocyanate was added dropwise. If you continue stirring,
An exothermic reaction occurred and a large amount of white solid precipitated. Reaction mixture
The mixture was heated at 90 ° C. for 1 hour, cooled and filtered by filtration to 5
8.0 g of white crystals were obtained. The melting point was 166 ° C.
Obtained by NMR measurement, mass spectrometry and IR measurement
The compound was identified as the desired product.

[0027]Synthesis Example 2 N- (p-toluenesulfoni
) -N '-(o-tolyl) urea The same operation as in Synthesis Example 1 was performed. However, 18.6g
Use 10.7 g of o-toluidine instead of aniline
20.7 g of toluenesulfonyl isocyanate
Using. 30.0 g of white crystals were obtained. Melting point is 148 ° C
Met. By NMR measurement, mass spectrometry and IR measurement
The resulting compound was identified as the target compound.

[0028]Synthesis Example 3 N- (p-toluenesulfoni
) -N '-(p-tolyl) urea The same operation as in Synthesis Example 2 was performed. However, 18.6g
Use 10.7 g of p-toluidine instead of aniline
Was. 29.6 g of white crystals were obtained. Melting point is 149 ° C
Was. Obtained by NMR measurement, mass spectrometry and IR measurement
The identified compound was identified as the target compound.

Synthesis Example 4 N- (benzenesulfonyl)-
To a three-necked flask equipped with a N'-phenylurea dropping funnel, a thermometer, and a reflux condenser, 6.3 g of benzenesulfonamide was placed, and 10 m
It was dissolved in a mixed solvent of 1 pyridine and 10 ml of tetrahydrofuran. While stirring the reaction solution with a magnetic stirrer, 5.0 g of phenyl isocyanate was added dropwise from a dropping funnel. The reaction solution is heated and refluxed for 3
Allowed to react for hours. After the reaction was completed, the reaction product was poured into water and adjusted to be weakly acidic with dilute hydrochloric acid to precipitate a white solid,
After filtration and drying, 10.6 g of white crystals were obtained. Melting point is 1
53 ° C. The obtained compound was identified as the target product by NMR measurement, mass spectrometry and IR measurement.

Example 1 A thermosensitive recording paper was prepared by the following operation. Using a sand grinder dispersion A prepared INGREDIENT AMOUNT (parts) 3- (N-isopentyl -N- ethyl-20-amino) -6-methyl-7-anilinofluoran polyvinyl alcohol 10% solution 10 Water 70 The composition The powder was pulverized until the average particle diameter became 1 μm or less.

[0031] Dispersion B prepared INGREDIENT AMOUNT (parts) N-(p-toluenesulfonyl) - 10 N '- (p-tolyl) urea oxalate di para methylbenzyl ester 10 polyvinyl alcohol 10% solution 10 Water 70 The above composition The product was pulverized using a sand grinder until the average particle size became 1 μm or less.

Preparation of Pigmented Undercoat Paper 85 parts of calcined clay (trade name Ansilex) in 320 parts of water
In a dispersion obtained by dispersing styrene-butadiene copolymer emulsion (solid content: 50%), 40 parts, 10%
48 g of a coating liquid obtained by mixing 50 parts of an oxidized starch aqueous solution
/ M ² base paper was applied so that the coating amount after drying was 7.0 g / m ² to obtain a pigment-coated paper.

Formation of color-developing layer 50 parts of the above solution A, 200 parts of solution B, calcium carbonate pigment 3
3 parts, 20 parts of 25% zinc stearate dispersion, 15 parts of 30% paraffin dispersion, and 120 parts of 10% polyvinyl alcohol aqueous solution were mixed and stirred to obtain a coating liquid. This coating solution was applied to one surface 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, thereby preparing a thermosensitive recording paper. The thermal recording paper obtained as described above is processed with a super calendar,
The smoothness of the surface was set to 600 to 1000 seconds.

The thus-obtained sample was color-developed with an applied energy of 0.39 mj / dot using a dynamic color tester which is a commercial thermal facsimile machine manufactured by Hitachi, Ltd. Color density is Macbeth reflection densitometer RD-9
The whiteness of the white paper portion of the sample was measured with a Hunter whiteness meter (blue filter). Table 1 shows the test results.

Example 2 The same operation as in Example 1 was performed. However, in the preparation of the dispersion liquid B, N- (p-toluenesulfonyl) -N'-
N- (p-toluenesulfonyl) -N'-phenylurea was used instead of (p-tolyl) urea, and oxalic acid dibenzyl ester was used instead of oxalic acid diparamethylbenzyl ester. Table 1 shows the test results.

Comparative Example 1 The same operation as in Example 1 was performed. However, in preparing the dispersion liquid B, N- (p-toluenesulfonyl) -N ′ was used.
2,2-bis (4-hydroxyphenyl) propane (bisphenol A) was used instead of-(p-tolyl) urea. Table 1 shows the test results.

Comparative Example 2 The same operation as in Example 1 was performed. However, in preparing the dispersion liquid B, N- (p-toluenesulfonyl) -N ′ was used.
N-N'-diphenylurea was used instead of-(p-tolyl) urea. Table 1 shows the test results.

[Table 1]

Example 3 A thermosensitive recording paper was prepared in the same manner as in Example 1 except for the following matters.

[0039] Preparation Ingredients Amount of Dispersion C (parts) bis (4- (1-aziridinyl carbonyl 20) phenyl) methane polyvinyl alcohol 10% solution 10 Water 70 The composition using a sand grinder to an average particle It was pulverized until the diameter became 1 μm or less.

Formation of Coloring Layer 50 parts of solution A described in Example 1 and solution 2 described in Example 2
00 parts, the above C liquid 50 parts, calcium carbonate pigment 23 parts,
20 parts of 25% zinc stearate dispersion, 15 parts of 30% paraffin dispersion, and 120 parts of 10% polyvinyl alcohol aqueous solution were mixed and stirred to obtain a coating liquid. This coating solution is applied to one side of a pigment-undercoated paper in an amount of 5.0 after drying.
Applying and drying so as to be g / m ² to form a thermosensitive coloring layer,
A thermal recording paper was prepared. The thermal recording paper obtained as described above was treated with a super calender and the surface smoothness was adjusted to 600 to 1000 seconds.

The thus-obtained sample was color-developed with an applied energy of 0.39 mj / dot using a dynamic color tester which was a commercial heat-sensitive facsimile machine manufactured by Hitachi Ltd. Color density is Macbeth reflection densitometer RD-9
It was measured at 14. Then, a predetermined test piece was prepared from this color-developed sample, and (a) within 30 minutes after color development, and (b) after 5 hours, the test piece was coated with salad oil or dioctyl terephthalate (representative plasticizer) and allowed to stand at room temperature. After standing for 3 hours, excess oil or plasticizer was wiped off, and the residual image density was measured with a Macbeth reflection densitometer, which was taken as a value representative of image storability. The test results are shown in Tables 2 and 3.

Example 4 The same operation as in Example 3 was performed. However, in the preparation of the dispersion liquid B, N- (p-toluenesulfonyl) -instead of N- (p-toluenesulfonyl) -N'-phenylurea
Used for N '-(o-tolyl) urea. The test results are shown in Tables 2 and 3.

Example 5 The same operation as in Example 3 was performed. However, in preparation of the liquid C used for forming the thermosensitive coloring layer, 2,4-bis (1-aziridinylcarbonylamino) was used instead of bis (4- (1-aziridinylcarbonylamino) phenyl) methane. ) Toluene was used. The test results are shown in Tables 2 and 3.

Example 6 The same operation as in Example 3 was performed. However, in the formation of the thermosensitive coloring layer, 40 parts of A solution, 120 parts of B solution, 40 parts of C solution,
43 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, 15 parts of 30% paraffin dispersion, and 1
120 parts of 0% polyvinyl alcohol aqueous solution was mixed and stirred to obtain a coating liquid. This coating liquid, the base paper side of 48 g / m ^2, the coating amount after drying by coating and drying so that 7.0 g / m ² to form a thermosensitive coloring layer to prepare a thermal recording paper. The test results are shown in Tables 2 and 3.

Example 7 The same operation as in Example 3 was performed. However, in preparing the solution A used for forming the thermosensitive coloring layer, 3-dibutylamino-6 was used instead of 3- (N-isopentyl-N-ethylamino) -6-methyl-7-anilinofluorane. -Methyl-7-anilinofluorane was used to prepare solution B.
N- (p-toluenesulfonyl) -instead of N- (p-toluenesulfonyl) -N '-(p-tolyl) urea
N'-benzenesulfonylurea was used. The test results are shown in Tables 2 and 3.

Comparative Example 3 The same operation as in Example 3 was performed. However, in the preparation of the liquid B used for forming the thermosensitive coloring layer, 2,2- instead of N- (p-toluenesulfonyl) -N'-phenylurea was used.
Bis (4-hydroxyphenyl) propane (bisphenol A) was used. The test results are shown in Tables 2 and 3.

[Table 2]

[0047]

[Table 3]

As is clear from Table 1 above, the novel developer of the present invention is bisphenol A which is a representative of conventional developers.
With the ability to develop color that surpasses. In addition, Tables 2 and 3 above
As is clearer, the heat-sensitive recording material using the novel color developer of the present invention in combination with the aziridine compound exhibits better oil resistance and plasticizer resistance immediately after color development.

[0049]

INDUSTRIAL APPLICABILITY The thermosensitive recording material of the present invention contains N-arylsulfonyl (thio) ureas having a specific chemical structure as a developer in the thermosensitive coloring layer, and therefore the thermosensitive coloring layer is It has superior color development performance to conventional color developers. Further, when the thermosensitive color developing layer further contains an aziridine compound, the obtained color image shows good oil resistance and plasticizer resistance immediately after color development.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-203381 (JP, A) JP-A-62-170388 (JP, A) JP-A-61-27287 (JP, A) JP-A-57- 38186 (JP, A) JP 59-165678 (JP, A) JP 56-99695 (JP, A) JP 4-282291 (JP, A) JP 4-358887 (JP, A) Japanese Examined Japanese Patent Sho 54-36507 (JP, B2)

Claims (2)

(57) [Claims] 1. A thermosensitive coloring layer comprising 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 color developer which reacts under heating to develop a color thereof. And the developer has the following general formula (I): [Wherein, X in the formula (I) represents an oxygen atom or a sulfur atom, R ₁ is substituted with at least one member selected from an aromatic group having no substituent, a lower alkyl group, and a halogen atom. Represents a member selected from the group consisting of a benzene ring group, R ₂ and R ₃ are each independently of the other, a hydrogen atom, an alkyl group, an aralkyl group, an alkyl group substituted with an aryloxy group, or an aromatic group having no substituent. Group, and at least one member selected from an alkyl group, an aryl group, an aralkyl group, an alkyloxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, an aralkyloxycarbonyl group, an arylsulfonyl group, and a halogen atom. Represents a member selected from aromatic groups. ] A thermosensitive recording medium comprising at least one compound represented by 2. The thermosensitive coloring layer further comprises at least one.
The thermosensitive recording medium according to claim 1, which contains an organic compound having one aziridinyl group.