JPH04358887A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal recording medium with excellent color development and high whiteness by forming a thermal color development layer containing colorless or pale dye precursor and N-arylsulfonyl (thio or dithio) ester cabamoylate of specific chemical structure as a color developer, on a sheet-like base. CONSTITUTION:A chemical compound expressed by formula I is used as a color developer. In the formula, X, Y are O or S and R1 is a non-substituted aromatic ring group and a benzene ring group substituted by aryl, aralkyl or halogen. R2 is an aralkyl group, an aralkyl group substituted by aryloxy, a non-substituted or substituted aromatic ring group. The substituted group of the aromatic ring group is an alkyl group, an alkenyl group, an aralkyl group, an alkyloxy group, an alkylmercapto group, an alkyloxycarbonyl group or halogen. In addition, if an organic aziridinyl group is added to the thermal color development layer, it is possible to obtain a color developed image which is highly resistant against oil and plasticizer immediately after color development.

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 that forms a colored image by heating. More specifically, the present invention relates to a heat-sensitive recording material that has excellent oil resistance and plasticizer resistance, high whiteness, no loss of colored images over time, and excellent recording storage stability. Such a heat-sensitive recording material is suitable for use in image recording paper, facsimile paper, cash dispenser paper, train tickets, commuter passes, labels such as POS labels, cards such as prepaid cards, and pass tickets.

0002

[Prior Art] Thermosensitive recording materials are generally made by coating a support such as paper, synthetic paper, or plastic film with a color-forming substance such as an electron-donating leuco dye and an organic acidic substance such as an electron-accepting phenolic compound. A heat-sensitive coloring layer is provided which has a color-developing substance as a main component, and a recorded image can be formed by causing these coloring components to react with thermal energy. Such heat-sensitive recording bodies are disclosed in, for example, Japanese Patent Publications No. 43-4160, Japanese Patent Publication No. 45-14039, and Japanese Patent Publication No. 48-27736, and have been widely put into practical use.

[0003] The above-mentioned heat-sensitive recording medium is used as a recording device that is compact, inexpensive, and easy to maintain, so it can be used as an output of an electronic computer, a facsimile machine, an automatic ticket vending machine, a printer of scientific measuring instruments, or a CRT medical measuring device. Widely used in printers, etc. However, in conventional so-called dye-type thermosensitive recording materials in which a thermosensitive coloring layer containing a coloring dye substance, a color developer substance, and a binder as active ingredients is coated on a support, the coloring reaction is reversible. Therefore, there is a problem that the colored image fades over time. This decoloring phenomenon is accelerated by exposure to light, high humidity, and high temperature atmospheres, and especially when it comes into contact with plasticizers, oils, etc., it progresses rapidly, and as a result, colored images are decolored to an unreadable level. be.

[0004] Many techniques have been disclosed for suppressing the color fading phenomenon when using a coloring system using a dye precursor mainly consisting of a colorless or light-colored lactone ring compound. For example, JP-A-60-78782, JP-A-59-167
No. 292, JP-A-59-114096, and JP-A-59-93387, in which a phenolic antioxidant is blended into the heat-sensitive coloring layer;
As seen in No. 146796, a protective layer made of a hydrophobic polymer compound emulsion etc. is arranged, JP-A No. 5
As seen in Publication No. 8-199189, an intermediate layer formed from a water-soluble polymer compound or a hydrophobic polymer compound emulsion is provided on the heat-sensitive coloring layer, and a hydrophobic polymer compound is formed as a resin component on top of the intermediate layer. There are known those in which a surface layer is provided with an oil-based paint, or those in which an epoxy compound or an aziridine compound is contained in a heat-sensitive coloring layer, as shown in JP-A-62-164579.

Colored images formed by the heat-sensitive coloring layer containing the aforementioned phenolic antioxidant have been somewhat improved in terms of environmental resistance such as heat resistance and moisture resistance; There is little information regarding the retention rate of image density after a certain period of time when it is brought into contact with a coloring surface), plasticizer resistance (the retention rate of image density after a certain period of time when dioctyl phthalate is brought into contact with a coloring surface), etc. No improvement is recognized. On the other hand, a heat-sensitive recording material provided with a protective layer or a surface layer has considerably improved environmental resistance. However, in terms of oil resistance and plasticizer resistance, image preservation is improved when the surface comes in contact with salad oil or dioctyl phthalate, but when it comes into contact with the back or edge, the penetration of salad oil or dioctyl phthalate increases. As a result, the image almost completely disappears. This is not an essential solution to the above problems. Furthermore, in the case of a thermosensitive coloring layer containing an epoxy or aziridine compound, it takes a relatively long time to stabilize the colored image after the heating coloring operation. The disadvantage is that when salad oil or dioctyl phthalate is applied to a colored image, a large portion of the colored image is erased. Further, JP-A-60-18487 and JP-A-2-266977 disclose that a heat-sensitive coloring layer contains a carbamoylic acid ester compound. However, the compounds described in the above publication are
It was unsatisfactory in its color developing ability and color image stabilizing effect.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a heat-sensitive recording medium which has excellent whiteness, oil resistance, plasticizer resistance, etc., and therefore has excellent storage stability of colored images. It is an attempt to provide the body. For example, the present invention can be used not only as a thermal recording type ticket for automatic ticket vending machines, but also for use in coupon tickets and commuter passes that require long shelf life, and for plastics that inevitably come into contact with plasticizers and oils. It can be used as a label for POS barcode systems that is attached to the packaging surface of food products packaged with vinyl chloride film, and can also be used as facsimile paper and word processing paper for long-term storage, as well as image printer paper for CRT. The aim is to provide a record.

[0007]

[Means for Solving the Problems] The present inventors have developed a heat-sensitive film that exhibits the effect of improving the storage stability of colored images, such as oil resistance and plasticizer resistance, within as short a time as possible after forming colored images. We investigated ways to improve the coloring layer, and as a result, we developed a group of N-arylsulfonyl (thio or dithio) with a specific chemical structure.
The carbamoylic acid ester compound has excellent color developing ability and whiteness improvement effect, and by combining this compound with the aziridine compound, it has excellent oil resistance and plasticizer resistance, and therefore has excellent long-term properties. A heat-sensitive color forming layer having a storage stabilizing effect can be obtained, and even though these compounds do not have acidic functional groups such as phenolic hydroxyl groups and carboxyl groups, they can be contacted with dye precursors under heating. Then, they discovered that it has a color developing ability that can sufficiently develop color, leading to the completion of the present invention.

The heat-sensitive recording material of the present invention includes a sheet-like substrate, a colorless or light-colored dye precursor formed on at least one surface of the sheet-like substrate, and a color developer that develops color by reacting with the dye precursor under heating. and a thermosensitive coloring layer containing the color developer, the color developer having the following general formula (I):

[Formula 2] [However, X and Y each independently represent an oxygen atom or a sulfur atom, and R1 is an aromatic ring group having no substituent, a lower alkyl group, an aryl group,
and a benzene ring group substituted with at least one member selected from a halogen atom,
R2 is an aralkyl group, an alkyl group substituted with an aryloxy group, an aromatic ring group without a substituent, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkyloxy group, an aryloxy group, an aralkyl group. From aromatic ring groups substituted with at least one member selected from oxy group, alkylmercapto group, arylmercapto group, aralkylmercapto group, alkyloxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, and halogen atom Represents one selected member. ] It is characterized by containing at least one kind of compound represented by.

Further, in the heat-sensitive recording material of the present invention, it is preferable that the heat-sensitive coloring layer further contains an organic compound having at least one aziridinyl group. The aziridinyl group has the following chemical formula:

[Chemical 3] is expressed by

0010

[Function] The N-arylsulfonyl (thio or dithio) carbamoylate compound of formula (I) used in the present invention acts as a color developer. That is, the compound of formula (I) does not have a phenolic hydroxyl group or a carboxyl group, or has a
It has excellent color developing ability. This is the formula (I)
This is probably because the amino group in the compound is activated by the adjacent sulfonyl group and carboxyl group.

Specific examples of the compound of formula (I) are as follows. N-(p-toluenesulfonyl)carbamoylic acid phenyl ester (melting point 106°C), N-(p-toluenesulfonyl)carbamoylic acid 2,3,4-trimethylphenyl ester (melting point 144°C), N-(p-toluenesulfonyl) ) Carbamoylic acid benzyl ester (melting point 98°C), N-(p-toluenesulfonyl)carbamoylic acid 2-phenoxyethyl ester (melting point 120°C)
, N-(p-toluenesulfonyl)carbamoylic acid p-
Cumyl phenyl ester (melting point 120°C), N-(p
-Toluenesulfonyl)carbamoylic acid o-biphenyl ester (melting point 136°C), N-(p-toluenesulfonyl)carbamoylic acid 1-naphthyl ester (melting point 1
48°C), N-(p-toluenesulfonyl)carbamoylic acid 1-(4-methoxynaphthyl) ester, N-(p-toluenesulfonyl)carbamoylic acid 1-(4-methoxynaphthyl) ester,
-Toluenesulfonyl)carbamoylic acid p-benzyloxycarbonylphenyl ester (melting point 112-13
0 °C), N-(p-toluenesulfonyl)carbamoylic acid p-methoxycarbonylphenyl ester (melting point
176°C), N-(p-toluenesulfonyl)carbamoylic acid p-n-butoxycarbonylphenyl ester (
Melting point 113°C), N-(p-toluenesulfonyl)carbamoylic acid p-benzyloxyphenyl ester (melting point 122°C), N-(p-toluenesulfonyl)carbamoylic acid m-benzyloxyphenyl ester, N-
(p-Toluenesulfonyl)carbamoylic acid p-methoxyphenyl ester (melting point 95°C), N-(p-toluenesulfonyl)carbamoylic acid m-methoxyphenyl ester (melting point 96°C), N-(p-toluenesulfonyl)carbamoylic acid p-ethoxyphenyl ester (melting point 88°C), N-(p-toluenesulfonyl)carbamoylic acid p-n-butoxyphenyl ester (melting point 114
°C), N-(benzenesulfonyl)carbamoylic acid p-
Chlorophenyl ester, N-(p-toluenesulfonyl)carbamoylic acid 2-methoxy-4-allylphenyl ester (melting point 123°C), N-(p-toluenesulfonyl)carbamoylic acid p-methylmercaptophenyl ester (melting point 95°C), N-(p-toluenesulfonyl)carbamoylic acid 3-methyl-4-methylmercaptophenyl ester (melting point 105°C), N-(o-toluenesulfonyl)carbamoylic acid p-biphenyl ester, N-(p-toluenesulfonyl)carbamoyl acid p
-Benzylmercaptophenyl ester, N-(1-naphthalenesulfonyl)carbamoylic acid p-benzyl ester, N-(p-toluenesulfonyl)thiocarbamoylic acid p-tolyl ester (melting point 95°C), N-(p-toluenesulfonyl) Dithiocarbamoylic acid p-methylbenzyl ester. These compounds may be used alone or in combination of two or more thereof.

The N-arylsulfonyl (thio or dithio)carbamoylic acid ester compounds of formula (I) as described above are new compounds and can be synthesized by the following reactions (a) and (b). . (a) R1 -SO2NH2+ClC(=X)-Y-R2 →
Addition of base → Compound of formula (I) (b) R1 -SO2NCO+H-Y-R2 → Compound of formula (I) [However, in the above formula, R1, R2, X and Y are as defined above]

Further, as specific examples of the aziridinyl group-containing compound that can be used in the present invention, the following compounds can be mentioned. 2,4-bis(1-aziridinylcarbonylamino)toluene, bis(4-(1-aziridylcarbonylamino)phenyl)methane, bis(3-chloro-4-(1-aziridylcarbonylamino)phenyl) methane, 2,2
-bis(4-(1-aziridinylcarbonyloxy)phenyl)propane, 1,4-bis(1-aziridinylcarbonyloxy)benzene, and 1,4-bis(1-
aziridinylcarbonyl)benzene.

In the present invention, the leuco dye used as a dye precursor includes triphenylmethane-based, fluoran-based, diphenylmethane-based compounds, etc., and can be selected from conventionally known leuco dyes. For example, 3-(4-
diethylamino-2-ethoxyphenyl)-3-(1-
Ethyl-2-methylindol-3-yl)-4-azaphthalide, crystal violet lactone, 3-(N
-ethyl-N-isopentylamino)-6-methyl-7
-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6
Methyl-7-(o,p-dimethylanilino)fluorane, 3-(N-ethyl-N-p-toluidino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7- Anilinofluorane, 3-dibutylamino-
6-Methyl-7-anilinofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-7-(o-chloroanilino)fluorane, 3- diethylamino-7-
(m-trifluoromethylanilino)fluorane, 3-
diethylamino-6-methyl-7-chlorofluorane,
3-diethylamino-6-methylfluorane, and 3
-cyclohexylamino-6-chlorofluorane, 3-
(N-ethyl-N-hexylamino)-6-methyl-7
-1 selected from (p-chloroanilino)fluorane, etc.
More than one species can be used.

[0015] In addition to the compound of formula (I), the color developer used in the present invention may contain conventionally known color developer compounds consisting of phenols or organic acids, within a range that does not impede the desired effect. May contain. Such known color developer compounds include, 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-1-1
80382), 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 (Japanese Patent Application Laid-open No. 59-52694), 3,3'-diallyl-4,4'-dihydroxydiphenylsulfone (Japanese Patent Application Laid-Open No. 60-208286), etc. , these alone,
Alternatively, two or more kinds can be used in combination.

Furthermore, in the present invention, in the heat-sensitive coloring layer,
A thermofusible substance (so-called sensitizer) may be included within a range that does not inhibit the desired effect. As the sensitizer, a thermofusible organic compound with a melting point of 50 to 150°C is used, examples of which include 1-hydroxy-2-naphthoic acid phenyl ester (Japanese Patent Application Laid-open No. 191089/1989), p-
Benzyl biphenyl (JP 60-82382), benzyl naphthyl ether (JP 58-87094)
, dibenzyl terephthalate (JP-A-58-98285
No.), benzyl p-benzyloxybenzoate (Unexamined Japanese Patent Publication No. 5
7-201691), diphenyl carbonate, ditolyl carbonate (JP-A-58-136489), m-terphenyl (
JP-A-57-89994), 1,2-bis(m-tolyloxy)ethane (JP-A-60-56588), 1,
5-bis(p-methoxyphenoxy)-3-oxapentane (JP-A-62-181183), oxalic acid diester (JP-A-64-1583), 1,4-bis(p-
tolyloxy)benzene (JP-A-2-153783)
and so on.

The heat-sensitive layer of the present invention may further contain a hindered phenol compound or an ultraviolet absorber. These compounds are disclosed in, for example, JP-A-57-151394, JP-A-58-160191, and JP-A-58-6909.
No. 6, JP-A-59-2884, JP-A-59-9519
No. 0, JP-A-60-22288, JP-A-60-255
No. 485, JP-A-61-44686, JP-A-62-1
69683, JP-A-63-17081, and JP-A-1-249385, examples of which 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-t
ert-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, and tetra(2,2,6,6-tetramethyl-4-piperidyl)1,2, 3,4-butanetetracarboate and the like.

The heat-sensitive color forming layer of the heat-sensitive recording material of the present invention mainly comprises (a) a color developer containing a dye precursor and a compound of formula (I) of the present invention, or (b) a dye precursor and the above-mentioned compound of the present invention. A color developer containing a compound of formula (I) and an aziridine compound. Each heat-sensitive coloring layer may contain a conventionally known phenolic or organic acid color developer compound, sensitizer, antioxidant, ultraviolet absorber, or waxes, if necessary. Further, the thermosensitive coloring layer preferably contains organic or inorganic pigments. Furthermore,
The thermosensitive coloring layer contains a binder for fixing these components to the support.

The content of the dye precursor in the heat-sensitive coloring layer is generally preferably 5 to 20% by weight, and the content of the color developer containing the compound of formula (I) is generally 10% by weight.
It is preferably 50% by weight. If the content of the color developer is less than 10% by weight, the color developing ability may be insufficient, and if it exceeds 50% by weight, the color developing ability will be saturated and no particular improvement will be seen, resulting in economical problems. may be disadvantageous. When the thermosensitive coloring layer contains an aziridine compound, the content thereof is preferably 1 to 30% by weight. If the content is less than 1%, the effect of stabilizing image storage may become insufficient, and even if it is used in a large amount exceeding 30% by weight, the effect of improving storage stability is saturated and no further improvement is observed.

[0020] When an antioxidant or ultraviolet absorber is contained in the heat-sensitive coloring layer, the content thereof is preferably 1 to 10% by weight. If the content is less than 1% by weight, the effect of suppressing discoloration is small, and if it exceeds 10% by weight, the whiteness of the heat-sensitive recording material may decrease or problems may occur with the running properties of the recording material in the printing device. It may occur. When the heat-sensitive coloring layer contains a conventional phenolic or organic acid color developer compound, the content is preferably 5 to 40% by weight, and when a sensitizer is included, the content is 10% by weight. It is preferably 40% by weight. When waxes and white pigments are included in the heat-sensitive coloring layer, their content is preferably 5 to 20% by weight and 10 to 50% by weight, respectively, and the binder content is generally 5 to 2% by weight.
It is 0% by weight.

Examples of the above 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 inorganic fine powders such as calcium carbonate and silica, as well as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene. Examples include organic fine powder such as resin.

[0022] As the wax, known waxes such as paraffin, amide wax, bisimide wax, and metal salts of higher fatty acids can be used.

As for the binder, polyvinyl alcohol of 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, etc. Polymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt,
Water-soluble polymeric materials such as polyacrylamide, sodium alginate, gelatin, and casein, as well as polyvinyl acetate, polyurethane, styrene/butadiene copolymers, polyacrylic acid, polyacrylic esters, vinyl chloride/vinyl acetate copolymers , polybutyl methacrylate, ethylene/vinyl acetate copolymer, and styrene/butadiene/acrylic copolymer.

The sheet-like substrate used in the heat-sensitive recording medium of the present invention is paper, coated paper whose surface is coated with pigment, latex, etc., multilayer synthetic paper made from polyolefin resin, plastic film, or any of these. You can choose from composite sheets, etc. A coating liquid containing a mixture of the above-mentioned necessary components is applied onto at least one surface of such a sheet-like substrate and dried to produce a heat-sensitive recording material. The coating amount is 1 to 15 g/m2 when the coating liquid layer is dry.
It is preferably 2 to 10 g/m2, particularly preferably 2 to 10 g/m2.

In the heat-sensitive recording material of the present invention, a covering layer such as a protective layer, a printing layer, etc. may be further formed on the heat-sensitive coloring layer.

[0026] The present invention will be specifically explained below with reference to Examples.

[Example] In the following example, unless otherwise specified, "
"Parts" and "%" represent "parts by weight" and "% by weight," respectively.

Synthesis Example 1 (Synthesis of N-(p-toluenesulfonyl)-carbamoylic acid p-cumylphenyl ester) 10 g of p-toluenesulfamide was placed in a three-necked flask equipped with a dropping funnel, a thermometer, and a reflux device. was dissolved in 20 ml of pyridine. While stirring the solution thus obtained with a magnetic stirrer and cooling the flask with an ice bath, a solution of 16.9 g of chlorocarbonate cumyl phenyl ester dissolved in 20 ml of toluene was added dropwise from the dropping funnel. did. The dropping temperature was regulated to 20°C or less. After completion of the dropwise addition, the temperature of the obtained reaction solution was slowly returned to room temperature, the ice bath was replaced with an oil bath, and the reaction solution was reacted at 100° C. for 3 hours. After the reaction was completed, the reaction product was washed with 0.1N hydrochloric acid solution and extracted with ether. The resulting ether solution was washed with water, further dried over magnesium sulfate, and filtered. Ether was distilled off from this filtrate to obtain a toluene solution containing crystals. A small amount of toluene was added to this and recrystallized to obtain 19.4 g of white crystals. Its melting point is 120
It was ℃. The obtained compound was identified as the target compound by NMR measurement and IR measurement.

Synthesis Example 2 N-(p-toluenesulfonyl)-carbamoylic acid p-benzyloxyphenyl ester 5.0 g of hydroquinone monobenzyl ether was placed in a three-necked flask equipped with a dropping funnel, a thermometer, and a reflux device. This was dissolved in 20 ml of toluene at 80°C. While stirring the reaction solution with a magnetic stirrer,
5.2 g of p-toluenesulfonyl isocyanate was added dropwise from the dropping funnel. After the dropwise addition, several drops of pyridine were added, and the resulting reaction mixture was subjected to a reaction at 80° C. for 2 hours. After the reaction was completed, the reaction solution was cooled to room temperature, and white crystals were precipitated. 9.4 Collect this precipitate by filtration and dry it.
g white crystals were obtained. Its melting point was 122°C. The obtained compound was identified as the target compound by NMR measurement and IR measurement.

Example 1 A thermosensitive recording paper was prepared by the following procedure. The above composition was ground using a sand grinder until the average particle size was 1 μm or less.

[0030] The above composition was ground using a sand grinder until the average particle size became 1 μm or less.

■ Preparation of pigmented undercoated paper Disperse 85 parts of fired clay (trade name: Ansilex) in 320 parts of water.
A coating liquid was prepared by mixing 40 parts of a styrene-butadiene copolymer emulsion (solid content 50%) and 50 parts of a 10% oxidized starch aqueous solution into the obtained aqueous dispersion. This coating liquid was applied onto one surface of a 48 g/m2 base paper so that the coating amount after drying was 7.0 g/m2, and dried to prepare a pigment-primed paper.

■ Formation of heat-sensitive coloring layer 75 parts of the above liquid A, 150 parts of liquid B, 33 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, 30%
A coating solution for forming a heat-sensitive coloring layer was prepared by mixing and stirring 15 parts of a paraffin dispersion and 120 parts of a 10% polyvinyl alcohol aqueous solution. This coating solution was coated on one side of a base paper having a basis weight of 50 g/m2 so that the coated amount after drying was 5.0 g/m2, and dried to form a heat-sensitive color, thereby producing a heat-sensitive recording paper.

The heat-sensitive recording paper obtained as described above was treated with a supercalender to check the smoothness of its surface.
The time was 600 to 1000 seconds.

The sample thus obtained was subjected to a dynamic color development tester using a heat-sensitive facsimile manufactured by Hitachi, Ltd. modified for testing purposes, and an image was developed on the sample under the condition of applied energy of 0.46 mj/dot. The color density of the obtained colored image was measured using a Macbeth reflection densitometer RD-914. In addition, the whiteness of the blank portion of the sample was measured using a Hunter whiteness meter (Blue Filter). The test results are shown in Table 1.

Example 2 The same operation as in Example 1 was carried out. However, in preparing the color developer dispersion B, instead of N-(p-toluenesulfonyl)carbamoylic acid p-cumylphenyl ester,
N-(p-toluenesulfonyl)carbamoylic acid p-benzyloxyphenyl ester (melting point: 122°C (Synthesis Example 2)) was used. The test results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was carried out. However, in preparing color developer dispersion B, N-(p-toluenesulfonyl)
Instead of carbamoylic acid p-cumylphenyl ester, 2,2-bis(4-hydroxyphenyl)propane (
Bisphenol A (melting point: 156°C) was used. The test results are shown in Table 1.

Comparative Example 2 The same operation as in Example 1 was carried out. However, in preparing color developer dispersion B, N-(p-toluenesulfonyl)
Instead of carbamoylic acid p-cumylphenyl ester, 4-t-butylphenyl N-phenyl carbamate described in JP-A-60-184879 was used. The test results are shown in Table 1.

[Table 1]

Example 3 A thermosensitive recording paper was prepared by the following procedure. The above composition was ground using a sand grinder until the average particle size was 1 μm or less.

■ Formation of heat-sensitive coloring layer 50 parts of solution A described in Example 1, 150 parts of solution B, 50 parts of solution C, 30 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, 30% Paraffin dispersion 15
parts, and 10% polyvinyl alcohol aqueous solution 120
The components were mixed and stirred to prepare a coating solution. Apply this coating liquid to one side of the pigment undercoated paper to a coating amount of 5.0 g/m2 after drying.
The mixture was coated and dried to form a heat-sensitive color, and a heat-sensitive recording paper was prepared. The thermal recording paper obtained as above was
It was treated with a super calender to give a surface smoothness of 600 to 1000 seconds.

[0040] Regarding the sample thus obtained, an image was developed using a dynamic color development tester which was a modified heat-sensitive facsimile machine manufactured by Hitachi, Ltd. with an applied energy of 0.46 mj/dot. Color density is measured using Macbeth reflection densitometer RD-9.
Measured at 14. Next, a predetermined sample piece is prepared from this colored sample, and (a)
Within 30 minutes after color development, (b) 5 hours later, the test piece was immersed in salad oil, left at room temperature for 24 hours, and the remaining image density was measured using a Macbeth reflection densitometer, which is representative of image storage stability. value. The test results are shown in Table 2.

Example 4 The same operation as in Example 3 was carried out. However, color developer dispersion B
In the preparation of N-(p-toluenesulfonyl)carbamoylic acid p-cumylphenyl ester, N
-(p-Toluenesulfonyl)carbamoylic acid p-benzyloxyphenyl ester (melting point: 122°C) was used. The test results are shown in Table 2.

Example 5 The same operation as in Example 3 was carried out. However, in preparing the aziridinyl compound dispersion C used for forming the heat-sensitive coloring layer, 2,4-bis(1-aziridinylcarbonyl) was used instead of bis(4-(1-aziridinicarbonylamino)phenyl)methane. amino) toluene was used. The test results are shown in Table 2.

Example 6 The same operation as in Example 4 was carried out. However, in forming the heat-sensitive coloring layer, 40 parts of liquid A, 120 parts of liquid B, 40 parts of liquid C, 40 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, 15 parts of 30% paraffin dispersion, and % polyvinyl alcohol aqueous solution 120 parts mixed,
The mixture was stirred to prepare a coating solution. Apply this coating liquid with a basis weight of 48g.
/m2 of base paper, the coating amount after drying is 7.0g/m2.
A heat-sensitive coloring layer was formed by coating and drying to obtain a heat-sensitive recording paper. The test results are shown in Table 2.

Example 7 The same operation as in Example 4 was carried out. However, in preparing dye precursor dispersion A, 3-dibutylamino-6-methyl-7-instead of 3-(N-isopentyl-N-ethylamino)-6-methyl-7-anilinofluorane Anilinofluorane was used. The test results are shown in Table 2.

Comparative Example 3 The same operation as in Example 3 was carried out. However, in preparing the color developer dispersion B, instead of N-(p-toluenesulfonyl)carbamoylic acid p-cumylphenyl ester,
2,2-bis(4-hydroxyphenyl)propane (bisphenol A) was used. The test results are shown in Table 2.

Comparative Example 4 The same operation as in Example 3 was carried out. However, in preparing the color developer dispersion B, instead of N-(p-toluenesulfonyl)carbamoylic acid p-cumylphenyl ester,
4-t-butylphenyl N-phenyl carbamate described in JP-A-60-184874 was used. The test results are shown in Table 2.

[Table 2]

As is clear from Table 1, the novel color developer of the present invention is compatible with bisphenol A, which is a typical color developer of the conventional color developer.
It has a coloring ability comparable to that of the thermosensitive recording material, and the whiteness of the obtained thermosensitive recording material is significantly high. Further, as is clear from Table 2 above, the heat-sensitive recording material using the novel color developer of the present invention in combination with an aziridine compound exhibits good oil resistance and plasticizer resistance immediately after color development.

[0048]

Effects of the Invention The heat-sensitive recording material of the present invention contains an N-arylsulfonyl (thio or dithio) carbamoylate compound having a specific chemical structure as a color developer in its heat-sensitive color forming layer, and therefore, The heat-sensitive coloring layer has better coloring performance than conventional color developers, and also has better whiteness. In addition, when the thermosensitive coloring layer contains an aziridine compound, the coloring image obtained immediately after coloring is
Can exhibit good oil resistance and plasticizer resistance.

Claims (2)

[Claims] 1. A heat-sensitive coloring layer formed on at least one surface of the sheet-like substrate and containing a colorless or light-colored dye precursor and a color developer that reacts with heating to develop color. and the color developer has the following general formula (I): [Formula 1] [where X and Y each independently represent an oxygen atom or a sulfur atom, and R1 has a substituent aromatic ring groups, lower alkyl groups, aryl groups,
and one member selected from a benzene ring group substituted with at least one member selected from a halogen atom, R
2 is an aralkyl group, an alkyl group substituted with an aryloxy group, an aromatic ring group without a substituent, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkyloxy group, an aryloxy group, an aralkyl group From aromatic ring groups substituted with at least one member selected from oxy group, alkylmercapto group, arylmercapto group, aralkylmercapto group, alkyloxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, and halogen atom selected 1
represents a member. ] A thermosensitive recording material characterized by containing at least one compound represented by the following. 2. The thermosensitive coloring layer further contains an organic compound having at least one aziridinyl group.
The thermosensitive recording medium according to claim 1.