JPH05193268A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To enhance the sensitivity of a thermal recording medium, and improve the resistance against oil and plasticizer of a colored image to increase the long-term stability of a colored image by using a chemical compound containing two or more N-(meth)acrylolyaminocarbonyl group per molecule as a color developer contained in the thermal coloring layer of the thermal recording medium together with a dye precursor. CONSTITUTION:A thermal coloring layer consists of a sheet-like base, a colorless or pale color dye precursor formed, at least, on one surface of the sheet-like base, and a color developer which develops a color through a chemical reaction with the dye precursor under heating effects. The color developer contains, at least, one type of chemical compound selected from among those expressed by formulae I, II (X is O, S: R1 is H, a methyl group; R2 is H, an alkyl group, an aralkyl group, an amino group, an alkyl group substituted by an aryloxy group, an aromatic group without a substituted group; A is an organic group with a valence higher than divalence; n is an integer of 2 or higher). Consequently, enhancing the long-term stability of a colored image can be ensured.

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 has no loss of the once-colored image and is excellent in storage stability of the recorded image. More specifically, the present invention has good long-term storability of recorded images, and at the same time has moisture resistance of recorded images, and environmental resistance such as heat resistance, and oil resistance,
And excellent in plasticizer 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 pass 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 such as an electron-donating leuco dye and an organic compound such as an electron-accepting phenolic compound. A thermosensitive coloring layer containing a color-developing substance such as an acidic substance as a main component is provided, and a recording image can be formed by reacting these coloring components with thermal energy. Such thermal recording materials are disclosed in Japanese Examined Patent Publication No. 43-4160, Japanese Examined Publication No. 45-14039,
And Japanese Patent Publication No. 48-27636.
Widely used.

The thermal recording medium having the above construction has a compact recording apparatus, is inexpensive, and is easy to maintain. Therefore, the output of a computer, a facsimile, an automatic ticket vending machine, a printer of a scientific measuring instrument, or a CRT is used. It is used in a wide range of applications such as printers for medical measurement.
However, in a conventional so-called dye-type thermosensitive recording medium constituted by coating a thermosensitive color developing layer containing a color forming dye substance, a color developing substance and a binder on the support, the color reaction Is reversible, it is known that the color image disappears over time. This decoloring reaction is accelerated under exposure to light, high humidity, or high temperature atmosphere, and further progresses rapidly by contact with a plasticizer, oil, etc., and the image is erased to an unreadable level.

A number of techniques have been disclosed in order to suppress the above-mentioned decoloring phenomenon in a thermosensitive recording medium using a color-forming system using a dye precursor mainly composed of a colorless or light-colored lactone ring compound. For example, (1) JP-A-60-7
8782, JP-A-59-167292, JP-A-59
-114096 and a phenolic antioxidant as described in JP-A-59-93387 incorporated into a thermosensitive color-developing layer, and (2) high hydrophobicity as disclosed in JP-A-56-146796. What uses a molecular compound emulsion or the like for the protective layer, (3) JP-A-58-199189
As shown in No. 2, a water-soluble polymer compound or a hydrophobic polymer compound emulsion is provided as an intermediate layer on the thermosensitive coloring layer, and a surface layer made of an oil-based paint containing the hydrophobic polymer compound as a resin component is provided thereon. (4) JP-A-62
Containing an epoxy compound as disclosed in JP-A-164579, and (5) JP-A-62-169681
And the like, which uses a metal salt of a specific salicylic acid derivative as a color developer, as disclosed in No.

In the color-developed image of the heat-sensitive color-developing layer containing the above-mentioned phenolic antioxidant, the environmental resistance is slightly improved as compared with the image obtained without the thermosensitive color-developing layer, but oil resistance (eg salad) is improved. Preservation rate of image density after a certain time when oil is brought into contact with the coloring surface, and plasticizer resistance (image density after a certain time when a wrap film containing a plasticizer is brought into contact with the coloring surface) Preservation rate)
No improvement can be recognized. On the other hand, in the color image of the thermosensitive recording medium provided with the protective layer or the surface layer, the environmental resistance is slightly improved, but the decoloring after a long time is inevitable. Regarding the oil resistance, the image storability immediately after contact with oil is improved, but the image disappears almost completely as the oil permeates, and it cannot be said to be an essential solution to the above problems. . In the case where the thermosensitive coloring layer contains an epoxy compound, a relatively long time is required from the heating coloring operation to the time when the colored image is stabilized against oils and fats or plasticizers. Immediately after that, when salad oil is applied to the colored image or brought into contact with a plasticizer, a considerable part of the colored image is erased. Further, those using a specific metal salicylate as a color developer, the oil resistance and plasticizer resistance of the color image is improved, but the white paper part tends to color by heating,
It also has the drawback that the chemical structure of the particular effective salicylic acid is complex and expensive.

[0006]

The present invention solves the above problems in the prior art and is excellent in oil resistance, plasticizer resistance, moisture resistance, heat resistance, etc. of color images, and is therefore excellent in long-term storage stability. It is intended to provide a recording body. The present invention is useful, for example, as a thermal recording type ticket for an automatic ticket vending machine, and also a coupon ticket or a commuter ticket that requires preservability, and a plasticizer, or a packaging of a food packaged with a polyvinyl chloride film. It is suitable as a label for POS bar code system that is attached to the packaging surface where contact with oils and fats is inevitable, and can also be used as facsimile paper or word processor paper for long-term storage, and image printer paper for CRT. It is the one that seeks to provide the body.

[0007]

The inventors of the present invention have found that the effect of improving the storage stability such as oil resistance and plasticizer resistance of this color image is exhibited within the shortest possible time after formation of the color image. Efforts have been made to develop an improved thermosensitive coloring layer, and as a result, an N- (meth) acryloylaminocarbonyl group represented by the following formula (III):

[Chemical 2] A compound having two or more of the above-mentioned compounds has an excellent color-developing ability with respect to a dye precursor, and a color image obtained by the compound has high oil resistance and plasticizer resistance, and thus has an excellent long-term storage stabilizing effect. It was discovered that they have, and completed the present invention.

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

[Chemical 3] (In the above formula, X represents an oxygen or sulfur atom, and R
₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom, an alkyl group, an aralkyl group, an amino group, an alkyl group substituted with an aryloxy group, an aromatic group having no substituent, and an alkyl group. , An aryl group, an aralkyl group, an alkyloxy group, an alkyloxycarbonyl group,
Represents a member selected from an aryloxycarbonyl group, an aralkyloxycarbonyl group, an arylsulfonyl group, and an aromatic group substituted by at least one member selected from a halogen atom, and A has a valence of 2 or more. Represents an organic group, and n represents an integer of 2 or more. ) At least one selected from the compounds represented by

[0009]

In the compounds of the formulas (I) and (II) used in the present invention, the type represented by A is not limited as long as it has a valence of 2 or more, but the following groups are preferred. Compounds of a: a divalent or higher-valent organic functional group such as a carbonyl group, a thiocarbonyl group, and a sulfonyl group. b: a divalent or higher valent organic group derived from an aliphatic hydrocarbon. c: a divalent or higher valent organic group derived from an aliphatic hydrocarbon containing at least one hetero atom in the main chain. d: a divalent or higher valent organic group derived from an aliphatic hydrocarbon having at least one carbonyl group, thiocarbonyl group, imide group, imino group, sulfonyl group, or ester bond in the main chain. e: a divalent or higher valent organic group derived from an aliphatic hydrocarbon containing at least one substituted or unsubstituted aromatic hydrocarbon in the main chain. f: a divalent or higher valent organic group derived from an aliphatic hydrocarbon containing at least one substituted or unsubstituted heteroaromatic in the main chain. g: 2 derived from a substituted or unsubstituted aromatic hydrocarbon
Organic groups with a valency or higher. h: a divalent or higher valent organic group derived from a substituted or unsubstituted heteroaromatic ring. i: a divalent or higher valent organic group derived from a compound in which two or more aromatic hydrocarbons and a heteroaromatic ring compound are bonded with the organic groups a to d.

Typical examples of the groups belonging to the above a to i are shown below.

[Chemical 4]

[0011]

[Chemical 5]

The compounds of formulas (I) and (II) used in the present invention act as a developer for the dye precursor. That is, the compounds of the formulas (I) and (II) do not have an acidic functional group such as a phenolic hydroxyl group or a carboxyl group, but have a strong color developing ability for a dye precursor such as a basic leuco dye. Of. It is considered that this is because the amino group in the compounds of formulas (I) and (II) is activated by the (meth) acryloyl group adjacent thereto. Further, the image formed by the compounds of formulas (I) and (II) and the dye precursor is
The reason for high long-term storage stability under various environments is 1
It is considered to be due to the effect of N- (meth) acryloylaminocarbonyl groups (formula (III)) present in two or more in the molecule.

Formulas (I) and (II) used in the present invention
The following compounds can be mentioned as specific examples of the compound.

[Chemical 6]

[0014]

[Chemical 7]

[0015]

[Chemical 8]

[0016]

[Chemical 9]

The compounds of formulas (I) and (II) may be used alone or in combination of two or more. Many of the compounds of the formulas (I) and (II) as described above are novel compounds and can be synthesized, for example, by the following reactions (1) to (3).

[0018]

[Chemical 10]

The leuco dyes used as the dye precursor in the present invention include triphenylmethane type compounds, fluorane type compounds 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-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,
One or more selected from 3- (N-ethyl-N-hexylamino) -6-methyl-7- (p-chloroanilino) fluorane and the like can be used as the dye precursor.

Further, in the present invention, a conventionally known developer containing a phenol or an organic acid is added to the formula (I) and / or (II) of the present invention within a range that does not inhibit the desired effect.
Can be used in combination with the compound. Examples of these conventional developers include 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 (special Kaihei 1-18
No. 0382), 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) and 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone (JP-A-60-208286) are used. be able to.

Further, in the present invention, it is preferable to use a heat-fusible substance (so-called sensitizer) together in the heat-sensitive color forming layer. Such a sensitizer has a melting point of 50 ° C to 150 ° C.
The heat-fusible organic compound described in (1) is used, and for example, 1-hydroxy-2-naphthoic acid phenyl ester (JP-A-57-
191089), p-benzylbiphenyl (Japanese Patent Application Laid-Open No. Sho 6-62).
0-82382), benzylnaphthyl ether (JP-A-58-87094), dibenzyl terephthalate (JP-A-58-98285), benzyl p-benzyloxybenzoate (JP-A-57-201691), carbonic acid. Diphenyl, ditolyl carbonate (JP-A-58-136489)
No.), 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 thermosensitive coloring layer of the present invention may further contain a hindered phenol compound or an ultraviolet absorber. Such compounds are disclosed, for example, in JP-A-57-151.
394, JP-A-58-160191, JP-A-58-160191
69096, JP-A-59-2884, JP-A-59-
95190, JP-A-60-22288, JP-A-60
-255485, JP-A-61-44686, JP-A-62-169683, JP-A-63-17081, and JP-A-1-249385. , 1,3-tris (3′-cyclohexyl-4′-hydroxyphenyl) butane, 1,
1,3-tris (2-methyl-4-hydroxy-5-t
ert-butylphenyl) butane, 4,4′-thiobis (3-methyl-6-tert-butylphenol),
1,3,5-trimethyl-2,4,6-tris (3,5
-Di-tert-butyl-4-hydroxybenzyl) benzene, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, p-octylphenyl salicylate, 2- (2'-hydroxy-5'-methylphenyl)
Benzotriazole, ethyl-2-cyano-3,3'-
Diphenyl acrylate, and 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 comprises a dye precursor, a color-developing agent comprising at least one compound of the above-mentioned formulas (I) and (II) of the present invention, and if desired, an increased color. It contains a sensitizer. Further, the heat-sensitive color developing layer may contain conventionally known phenol-based or organic acid-based color developers, antioxidants, ultraviolet absorbers, or waxes, if necessary. The heat-sensitive color forming layer preferably contains organic or inorganic pigments, and further contains a binder for fixing these components to the sheet-shaped substrate.

The content of the above-mentioned dye precursor in the heat-sensitive color forming layer is generally preferably 5 to 20% by weight of the heat-sensitive color forming layer, and is selected from at least one compound of the formulas (I) and (II) of the present invention. The content of the developer is
It is preferably 50% by weight. When the content of the color developer is less than 10% by weight, the color developing ability is insufficient, and
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 contains an antioxidant or an ultraviolet absorber, the content thereof is generally 1 to 1 of the thermosensitive coloring layer.
It is preferably 10% by weight. When a conventionally known phenol-based or organic acid-based developer is used in combination with the developer of the present invention, its content is preferably 5 to 40% by weight. When a sensitizer is used, its content is preferably 10 to 40% by weight. When waxes or pigments are contained in the thermosensitive coloring layer, the content ratios thereof are 5 to 5
It is preferably 20% by weight and 10 to 50% by weight.
The content of the binder in the thermosensitive coloring layer is generally 5
Is about 20% by weight.

Examples of the above-mentioned organic or inorganic pigments include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, calcined clay, talc, and surface-treated calcium carbonate. 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 metal salt of higher fatty acid 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 thermosensitive recording medium of the present invention is made of paper, coated paper whose surface is coated with pigment, latex, etc., laminated paper, synthetic paper made of polyolefin resin, plastic film and the like. You can choose.

At least one surface of such a sheet-like substrate is coated with a coating solution containing a mixture of the above-mentioned required components and dried to form a thermosensitive coloring layer, thereby producing a thermosensitive recording material. The coating amount of the thermosensitive coloring layer is 1 to 15 when the coating liquid layer is dried.
is preferably a ^{g / m 2, 2~10g / m} 2 is particularly preferred. In the thermosensitive recording material of the present invention, a coating layer such as a protective layer or a printing layer may be further formed on the thermosensitive coloring layer.

[0031]

The present invention will be described in detail with reference to the following examples. Unless otherwise specified, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively.

Example 1 A thermosensitive recording paper was prepared by the following operation. 1) Preparation Component Parts by weight of the dispersion A 3- (N-isopentyl -N- ethylamino) -6-methyl-7 20 - the anilinofluoran polyvinyl alcohol 10% solution 10 Water 70 The composition of a sand grinder Used with an average particle size of 1
It was pulverized until it became less than μm.

[0033] 2) Dispersion Preparation Component Parts by weight of 4,4'-bis B (N-methacryloyl-amino-carbonyloxy) 10 - diphenylmethane (Compound No. 14) oxalate di -p- methylbenzyl ester 10 polyvinyl alcohol 10% Liquid 10 Water 70 Using the above composition with a sand grinder, the average particle size is 1
It was pulverized until it became less than μm.

3) Preparation of pigmented primer paper 85 parts of calcined clay (trademark: Ansilex) in 320 parts of water
40 parts of a styrene-butadiene copolymer emulsion (solid content: 50%) and 50 parts of a 10% oxidized starch aqueous solution were mixed with the resulting dispersion to prepare a coating solution. A pigment-undercoated paper was prepared by coating a high-quality paper having a basis weight of 48 g / m ² so that the coating amount after drying was 7.0 g / m ² .

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

5) Test For the above-mentioned thermal recording paper samples, a dynamic color tester, which is a modification of a commercial thermal facsimile machine manufactured by Hitachi, was used.
Color was developed with an applied energy of 0.49 mj / dot. The density of the obtained color image was measured with a Macbeth reflection densitometer RD-914.
Was measured (this is referred to as original image density). Next, a predetermined test piece was prepared from this color-developed sample, and within 30 minutes after color development, salad oil or dioctyl terephthalate (representative plasticizer) was applied to the test piece, and after standing at room temperature for 3 hours, Excess oil or plasticizer was wiped from the test piece, the residual image density was measured with a Macbeth reflection densitometer, and the image retention rate was calculated according to the following formula. Image preservation ratio (%) = D / D ₀ × 100 [wherein D ₀ represents the original image density and D represents the residual image density. The test results are shown in Table 1.

Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the preparation of the dispersion liquid B, 4,4′-bis (N-methacryloylaminocarbonylamino) -diphenylmethane (Compound No. 1 was used instead of 4,4′-bis (N-methacryloylaminocarbonyloxy) -diphenylmethane.
5) was used. The test results are shown in Table 1.

Example 3 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the preparation of the dispersion liquid B, 4,4′-bis (N-methacryloylaminocarbonylamino) -diphenylsulfone (compound No. 20 was used instead of 4,4′-bis (N-methacryloylaminocarbonyloxy) -diphenylmethane. ) Was used, and oxalic acid dibenzyl ester was used instead of oxalic acid di-p-methylbenzyl ester. The test results are shown in Table 1.

Example 4 A thermal recording paper was prepared in the same manner as in Example 1. However, in forming the thermosensitive coloring layer, 40 parts of A solution, 120 parts of B solution,
40 parts of calcium carbonate pigment, 20 parts of 25% zinc stearate dispersion, 15 parts of 30% paraffin dispersion, 120 parts of 10% polyvinyl alcohol aqueous solution, and 3 parts of wetting aid (trademark: Dapro U99, San Nopco) ,
Stir to give a coating solution. Synthetic paper (trademark:
(Yupo FPG-80, manufactured by Oji Yuka Synthetic Paper Co., Ltd.) was coated and dried so that the coating amount after drying was 8.5 g / m ² to form a thermosensitive coloring layer, thus preparing a thermosensitive recording paper. .. The test results are shown in Table 1.

Example 5 A thermal recording paper was prepared 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.

Comparative Example 1 A thermosensitive recording paper was prepared in the same manner as in Example 1. However,
In preparing Dispersion B, 2,2-bis (4-hydroxyphenyl) was used instead of 4,4′-bis (N-methacryloylaminocarbonyloxy) -diphenylmethane.
Propane (bisphenol A) was used. The test results are shown in Table 1.

[0042]

[Table 1]

As is clear from Table 1 above, the novel color developer used in the present invention shows much better oil resistance and plasticizer resistance than the conventional representative color developer, bisphenol A. A colored image can be formed.

[0044]

The thermosensitive recording medium of the present invention comprises a compound having two or more N- (meth) acryloylaminocarbonyl groups (formula III) in one molecule as a developer in the thermosensitive coloring layer. Therefore, the color-developed image formed on the thermosensitive color-developing layer exhibits excellent oil resistance and plasticizer resistance immediately after color development.

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[Procedure amendment]

[Submission date] February 24, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

[0016]

[Chemical 9]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

[0042]

[Table 1]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044]

INDUSTRIAL APPLICABILITY The thermosensitive recording material of the present invention has two or more N- (meth) acryloylaminocarbonyl groups (formula (III) ) in one molecule as a developer in the thermosensitive color developing layer. Therefore, the color image formed on the thermosensitive color developing layer contains a compound, and thus exhibits excellent oil resistance and plasticizer resistance immediately after color development.

Claims (1)

[Claims] 1. A sheet-like substrate, a colorless or light-colored dye precursor which is formed on at least one surface of the sheet-like substrate, and a developer which reacts with the dye precursor under heating to develop a color. A thermosensitive coloring layer containing an agent, wherein the developer is represented by the following general formulas (I) and (II): (In the above formula, X represents an oxygen or sulfur atom, and R
₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom, an alkyl group, an aralkyl group, an amino group, an alkyl group substituted with an aryloxy group, an aromatic group having no substituent, and an alkyl group. Group, an aryl group, an aralkyl group, an alkyloxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, an aralkyloxycarbonyl group, an arylsulfonyl group, and an aromatic group substituted with at least one member selected from a halogen atom. A represents an organic group having a valence of 2 or more, and n represents an integer of 2 or more. ) A thermal recording material containing at least one selected from the compounds represented by