JPH10315633A - Thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording medium having a recording image part and a ground color (unrecorded part) with excellent heat resistance and plasticizer resistance. SOLUTION: In the thermal recording medium comprising a colorless or light color dye precursor, a recording layer containing developer for color developing in reaction with the precursor as a main component on a support, the developer is at least one type of compound represented by a formula and the recording layer contains at least one type of polyurea compound, where X indicates oxygen atom or sulfur atom, R indicates unsubstituted or substituted phenyl group, naphthyl group, aralkyl group, 1-6C lower alkyl group, 3-6C cycloalkyl group or 2-6C lower alkenyl group, Z indicates 1-6C lower alkyl group or electron absorbing group, and n indicates integer of 0 to 4, p indicates integer of 1 to 5 where n+p<=5 is satisfied.

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 medium having excellent heat resistance and plasticizer resistance.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording sheet is usually prepared by grinding and dispersing a colorless or pale-colored dye precursor and a developer such as a phenolic compound into fine particles, and then mixing the two to form a binder and filling. A coating solution obtained by adding an agent, a sensitivity enhancer, a lubricant and other auxiliaries is applied to a support such as paper, synthetic paper, film, plastic, etc. The color is developed by an instantaneous chemical reaction caused by heating with a pen, a laser beam or the like, and a recorded image is obtained.

[0003] These heat-sensitive recording materials include a measuring recorder, a computer terminal printer, a facsimile,
It is applied to a wide range of fields, such as automatic ticket vending machines and bar code labels, but with the diversification and advancement of performance of these recording devices, the required quality of thermal recording sheets has become higher. . For example, with the speeding up of recording, it is required to obtain a high-density and vivid color image even with a small amount of thermal energy, while preservation such as light resistance, heat resistance, water resistance, oil resistance and plasticizer resistance is required. There is a demand for a heat-sensitive recording sheet having excellent properties.

However, in a conventional heat-sensitive recording material in which a heat-sensitive recording layer containing a dye precursor, a color developer and a binder as main components is coated on a support, the developed image loses its color over time. Was known and had been a problem. This decolorization is accelerated under light, high temperature and high humidity atmospheres, and further progresses significantly due to prolonged standing in water, contact with oil such as salad oil, plasticizer contained in wrap film, etc. The image becomes unreadable.

[0005] In order to suppress such a decoloring phenomenon of a recorded image, various techniques have been disclosed for a thermosensitive recording medium containing a dye precursor and a developer as main components. For example, JP-A-60-78782 and JP-A-59-11409
JP-A-56-146794, in which a phenolic antioxidant is incorporated into a thermosensitive coloring layer as disclosed in JP-A-6-146.
As described in JP-A-62-164579, there are known those in which a hydrophobic polymer compound emulsion or the like is used for a protective layer and those in which an epoxy compound is used in combination with a phenol-based developer. Have been. However, the effect of these additives on the plasticizer was not sufficient, and decoloring over time remained a problem.

[0006] More recently, as systems for recording on plain paper, such as the electrophotographic system and the ink jet system, have become widespread, there have been more opportunities to compare thermal recording with these plain paper recordings. For example, it is required that the stability of an image be as high as that of toner recording, and the stability of a non-printed portion (blank paper portion or ground color portion) before and after recording be close to that of plain paper. In addition, when heat-sensitive recording paper is used as a food label that is sterilized at a high temperature, or when heat lamination is performed when cards such as lift tickets are manufactured, the background color portion is exposed to heat of about 100 ° C. The demand for stability is increasing.

[0007] Regarding the ground color stability to heat, see
JP-A-353490 uses 3-dibutylamino-7- (o-chloroanilino) fluoran as a dye,
A 4-hydroxydiphenylsulfone compound having a melting point of 120 ° C. or higher, and 2,2′-methylenebis (4,6-di-
A heat-sensitive recording material containing a mixture of sodium salt of tert-butylphenyl) phosphate and magnesium silicate, etc., is described, and is excellent in stability of a ground color portion and a recorded image portion even under a high temperature environment of about 90 ° C. Is disclosed.

The present inventors have proposed a heat-sensitive recording medium having heat resistance even at a high temperature of 100 ° C. or higher, as disclosed in
4727, JP-A-8-25810, JP-A-8-53407, JP-A-8-59603,
JP-A-8-132739, Japanese Patent Application No. 7-97021
In the specification, Japanese Patent Application No. 7-122393, or Japanese Patent Application No. 7-250789, a heat-sensitive recording material using an aminobenzenesulfonamide derivative as a developer is described. However, these heat-sensitive recording materials are excellent in heat resistance but unsatisfactory in plasticizer resistance. Further, the addition of the plasticizer-resistant auxiliary often deteriorates the heat resistance, which is an extremely excellent property of the aminobenzenesulfonamide derivative.

[0009]

Therefore, the present invention solves the above-mentioned problems of the prior art, and has high heat resistance and excellent plasticizer resistance in a recorded image area and a ground color (unrecorded area). The object was to provide a heat-sensitive recording medium.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to provide a recording layer comprising, as a main component, a colorless or pale-colored dye precursor and a color developer which reacts with the dye precursor to form a color. In the heat-sensitive recording medium provided, the color developer is at least one compound represented by the following general formula (1), and the recording layer contains at least one polyurea compound. .

[0011]

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(Wherein, X represents an oxygen atom or a sulfur atom, R is an unsubstituted or substituted phenyl group,
It represents a naphthyl group, an aralkyl group, a lower alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a lower alkenyl group having 2 to 6 carbon atoms. Z has 1 to 1 carbon atoms
6 represents a lower alkyl group or an electron-withdrawing group. n is 0
Represents an integer of 1 to 4, and p represents an integer of 1 to 5. Where n
It is assumed that + p ≦ 5 is satisfied. )

In the present invention, the aminobenzenesulfonamide derivative represented by the general formula (1) used as a color developer has a structural change from the neutral structure of the general formula (1) (keto-type structure in the case of urea). Is caused to change to an acidic structure (enol-type structure in the case of urea), thereby exhibiting a color developing ability. Since the thermal head that supplies heat instantaneously rises to a high temperature of 200 to 300 ° C. or more, the compound of the general formula (1) contained in the recording layer causes tautomerism to become an acidic type and exhibit a developing function. It is thought to be expressed. As a result, the lactone ring of the dye precursor is cleaved to form a color.

A high temperature is an essential condition for the above-mentioned tautomerism, and is hardly caused by a plasticizer or the like. Therefore, when a compound having these structures is used as a color developer, the color development reaction does not occur even if the plasticizer comes into contact with the ground color portion, and the problem of ground color development by the plasticizer is extremely reduced. .

Further, the temperature at which the compound of the general formula (1) changes to an acidic structure (enolization or thiolation) is considered to be higher than the temperature required for heat lamination or sterilization by heating. Therefore, even in a high-temperature heat environment, the structure does not change to an acidic structure and the function of the developer is not expressed, so that the thermal stability of the ground color portion is increased.

In the aminobenzenesulfonamide derivative represented by the general formula (1), an aminosulfonyl group (—SO ₂ NH ₂ ) contributes to promotion of a color developing function and stabilization of an acidic structure. It is estimated to be. In order to stabilize the acidic structure showing a developing ability after heating, the N-position (or 1-position) of the urea structure or thiourea structure of the above general formula is required.
Aromatic ring may exist with position) in aminosulfonyl group (-SO ₂ NH _2). An aminosulfonyl group (—SO ₂ N
When H ₂ ) is present at the ortho position or the meta position, the coloring property at a lower heat energy (recording energy) is better than that at the para position, so that it can be preferably used.

R in the general formula (1) is not particularly limited as long as it does not impair the color developing ability and stability. For example, unsubstituted or substituted phenyl, naphthyl, aralkyl, C 1 -C 1 A lower alkyl group having 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a lower alkenyl group having 2 to 6 carbon atoms. Further, R in the general formula (1) includes:
Substituents that do not impair color development and heat resistance can be added. Examples of the substituent include a lower alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group, a lower alkenyl group such as an isopropenyl group, and an electron-withdrawing group such as fluorine, chlorine, bromine, and a nitro group. . Further, Z in the general formula (1) may be any substituent that does not impair color development and heat resistance. Examples of such a substituent include a lower alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group, or fluorine,
Examples thereof include electron-withdrawing groups such as chlorine, bromine, and nitro groups.

On the other hand, when the polyurea compound used in the thermal recording medium of the present invention is used together with the aminobenzenesulfonamide derivative represented by the general formula (1) used in the present invention, This compound gives the thermosensitive recording medium of the present invention a stronger plasticizer resistance while maintaining the extremely high heat resistance which is a property of the compound of the formula (1). Particularly, in the present invention, a polyurea compound having a repeating unit represented by the following general formula (2) or (3) is effectively used from the viewpoint of the action and effect with an aminobenzenesulfonamide derivative.
These may be used alone or in combination of two or more.

[0019]

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(However, A ¹ represents a divalent group.)

[0021]

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(However, ^one of R ¹ and R ² represents a hydrogen atom and the other represents a methyl group. A ² represents a divalent group.)

Once the aminobenzenesulfonamide derivative represented by the general formula (1) takes an acidic structure by the heat supplied from the thermal head, for example, it is represented by the general formula (2) or (3) The polyurea compound contributes to promoting the color developing function and stabilizing the acidic structure so as to promote the effect of the aminosulfonyl group of the general formula (1).
The reason for this has not been clearly elucidated, but is presumed as follows. Generally, in a thermosensitive recording medium, when a developer and a dye precursor react by thermal melting, electrons are transferred between the two to form a kind of charge transfer complex,
By solidification, a colored image is obtained. If a plasticizer adheres to this, the color-developed image dissolves in the plasticizer, thereby weakening the bonding force inside the complex, and eventually returns to the original dye precursor and developer, causing a decoloring phenomenon.

In the case of the present invention, when the developer of the general formula (1) reacts with the dye precursor, it is presumed that the polyurea compound is also melted by heat to form one charge transfer complex. .
Since the charge transfer complex is considered to have extremely low solubility in the plasticizer, the plasticizer is hardly penetrated into the image, and the bonding force inside the complex is hardly changed.
Further, it is considered that the polyurea compound acts to stabilize the acidic structure of the color developer of the general formula (1) and maintain the bonding force inside the complex. In addition, since the polyurea compound does not have a low melting point, it does not hinder the extremely high heat resistance, which is the characteristic of the general formula (1). Therefore, it is possible to obtain a heat-sensitive recording material that is extremely excellent in plasticizer resistance without decoloring even when in contact with a strong image decoloring substance such as a plasticizer while maintaining high heat resistance.

The amount of the polyurea compound of the present invention contained in the color-forming layer may vary depending on the required quality. The effect is insufficient, and if the amount is more than 5 parts per part of the developer, it is difficult to obtain a sufficient initial color density. Therefore, the content of the polyurea compound is 0.1 to 1 part of the developer.
It is desirable to use from 01 to 5 parts, more preferably from 0.1 to 2 parts.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION In order to obtain a compound represented by the general formula (1) used in the present invention, as an example, an aminobenzenesulfonamide having an aminosulfonyl group and an isocyanate or an isothiocyanate It can be produced by the reaction of esters. That is, in the reaction, the isocyanate ester or the isothiocyanate ester is added at a ratio of 1 to 2.5 mol per 1 mol of the aminobenzenesulfonamide. As the solvent to be used, the above-mentioned aminobenzenesulfonamides,
Any solvent capable of dissolving isocyanates or isothiocyanates can be used.Examples include aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated aromatic hydrocarbons such as chloroform, dichloromethane, and chlorobenzene; and diethyl ether. , Ethers such as tetrahydrofuran, acetonitrile, nitriles such as propionitrile, esters such as ethyl acetate, acetone, ketones such as methyl ethyl ketone,
Non-proton-donating polar solvents such as dimethylformamide and dimethylsulfoxide; alcohols such as methanol and ethanol; and mixed solvents thereof.
Reaction temperatures range from 0 to 150 ° C.

Specific examples of the compound represented by the general formula (1) are shown below as (A-1) to (A-54);
Alternatively, (B-1) to (B-18) are exemplified, but the invention is not limited thereto.

[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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The polyurea compound used in the present invention can be synthesized by a conventionally known method. In that case,
(A) Diisocyanate and diamine are dissolved in an inert solvent such as dimethylacetamide, acetone, dimethylformamide, chlorobenzene, and dimethylsulfoxide, mixed under an inert gas atmosphere, and stirred at room temperature for several minutes to several hours. Reaction method (ELLawton et al., J. Appl.P
olym.Sci., 25, 187 (1980), CSMarvel, JH Johnson, JA
m. Chem. Soc., 72, 1674 (1950)) or (b) a method in which a diamine and urea are mixed, heated, deammonified, and synthesized (Mitsui Toatsu, US Pat., 2973342 (1961)). . further,
(C) A method of synthesizing via reaction of diamine and phosgene via carbamic acid chloride (P. Borner et al., Makr
omol.Chem., 101, 1 (1967), L. Alexandru, L. Dascalu, J. Po
lym. Sci., 52, 331 (1961)), (d) Method of reacting diamine with water to synthesize via amino isocyanate (Y. Iwakura et al., Nikka Kagaku, 78, 1416 (1957)) , (E)
Synthesis by heating diamine and carbamate (Bri
t.Pat., 528437 (1940) and USPat., 2181663 (1940)),
(F) A method of synthesizing a diamine and carbon dioxide by heating under pressure (N. Yamazaki et al., J. Polym. Sci., Polym. Lett. E
d., 12,517 (1974)), (g) A method of synthesizing a diamine and carbon oxysulfide by heating under reduced pressure (GJMVa
n d. Kerk, Recueil. Trav. Chim., 74, 1301 (1955)),
(H) A method of synthesizing from diamine and diphenyl carbonate or di (p-nitrophenyl) carbonate (RDKatsarava et a
Chem., 194, 3209 (1993)), (i) a method of synthesizing from diisocyanate and benzoic acid in dimethyl sulfoxide (WR Sorensen, J. Org. Chem., 24, 978 (195)
9)) and the like. Although the polyurea compounds according to claims 2 and 3 of the present invention are thought to be able to be synthesized from any of the above methods, the methods (a) and (d), which are synthesized using diisocyanate, are particularly simple. is there.

When the polyurea compound used in the present invention is synthesized from diisocyanate, diphenylmethane-4,4'-diisocyanate (trade name: MDI) or toluylene-2,4-diisocyanate <2,4-TD as a raw material is used.
I>, toluylene-2,6-diisocyanate <2,6
-TDI> is very easily and inexpensively available because it is industrially produced in large quantities as a raw material for coatings, adhesives and polyurethane. Also, the production can be performed at a high yield without requiring any special equipment. Therefore, there is an advantage that the production cost of the compound of the present invention is very low. In the polyurea compound represented by the general formula (2) or (3) of the present invention, A ¹ and A ² represent a divalent group. Representative examples of the groups belonging to A ¹ and A ² are shown in the following formulas (4) and (5), but the present invention is not limited to these.

[0038]

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[0039]

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The following compounds are illustrated as specific examples of the compound of the general formula (2) or (3) used in the present invention, but the present invention is not limited thereto.

[0041]

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[0042]

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[0043]

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[0044]

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The general method for producing the thermosensitive recording medium of the present invention comprises a dye precursor, at least one compound represented by the general formula (1) as a color developer, and a compound represented by the general formula (2) or (3). The polyurea compound represented by the formula (1) is dispersed together with a binder, and if necessary, auxiliaries such as a filler, a lubricant, an ultraviolet absorber, a waterproofing agent, and an antifoaming agent are added to prepare a coating liquid. This is a method of coating and drying on a support by a usual method.

As the dye precursor to be used in the heat-sensitive recording material of the present invention, any of those known in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used and is not particularly limited. Compounds, fluorane compounds, fluorene compounds, divinyl compounds and the like are preferred. Specific examples of typical dye precursors are shown below. These dye precursors may be used alone or in combination of two or more.

<Triphenylmethane leuco dye> 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] 3,3-bis (p-dimethylaminophenyl) phthalide [ Aka malachite green lactone)

<Fluoran Leuco Dye> 3-Diethylamino-6-methylfluoran 3-Diethylamino-6-methyl-7-anilinofluoran 3-Diethylamino-6-methyl-7- (o, p-dimethylanilino ) Fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-7- (o-chloroanilino) Fluoran 3-diethylamino-6-methyl-7- (p-chloroanilino) fluoran 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-diethylamino-6-methyl-7-n-octylanilino Fluoran 3-diethylamino-6-methyl-7-n-octylua Minofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl-7-dibenzylanilinofluoran 3-diethylamino-6-chloro-7-methylfluoran 3-diethylamino-6 -Chloro-7-anilinofluorane 3-diethylamino-6-chloro-7-p-methylanilinofluoran 3-diethylamino-6-ethoxyethyl-7-anilinofluoran 3-diethylamino-7-methylfluoran 3-diethylamino-7- (chloroanilino) fluoran 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-7- (o-chloroanilino) fluoran 3-diethylamino-7- (p-chloroanilino) fluoran 3 -Diethylamino-7- ( -Fluoroanilino) fluoran 3-diethylamino-benzo [a] fluoran 3-diethylamino-benzo [c] fluoran 3-dibutylamino-6-methyl-fluoran 3-dibutylamino-6-methyl-7-anilinofluoran 3 -Dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3-dibutylamino-6-methyl-7- (o-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (p -Chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-dibutylamino-6 -Methyl-chlorofluoran 3-dibutylamino-6-ethoxyethyl- 7-anilinofluoran 3-dibutylamino-6-chloro-7-anilinofluoran 3-dibutylamino-6-methyl-7-p-methylanilinofluoran 3-dibutylamino-7- (o-chloroanilino ) Fluoran 3-dibutylamino-7- (o-fluoroanilino) fluoran 3-n-dipentylamino-6-methyl-7-anilinofluoran 3-n-dipentylamino-6-methyl-7- (p- Chloroanilino) fluoran 3-n-dipentylamino-6-chloro-7-anilinofluoran 3-n-dipentylamino-7- (p-chloroanilino) fluoran 3-n-dipentylamino-7- (m-trifluoromethyl Anilino) fluorane 3-pyrrolidino-6-methyl-7-anilinofluoran 3-piperidino-6-methyl 7-anilinofluoran 3- (N- methyl -N- propylamino) -6-methyl-7-anilinofluoran 3- (N- methyl -N- cyclohexylamino) -6-
Methyl-7-anilinofluoran 3- (N-ethyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-xylamino) -6-methyl-
7- (p-chloroanilino) fluoran 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilino Fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-ethoxypropylamino) -6
-Methyl-7-anilinofluoran 3-cyclohexylamino-6-chlorofluoran 2- (4-oxahexyl) -3-dimethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-diethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-dipropylamino-
6-methyl-7-anilinofluoran 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluoran 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluoran 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluoran 2,4-dimethyl- 6-[(4-dimethylamino) anilino] -fluoran

<Fluorene Leuco Dye>3,6,6'-Tris (dimethylamino) spiro [fluorene-9,3'-phthalide] 3,6,6'-Tris (diethylamino) spiro [fluorene-9,3 '-Phthalide]

<Divinyl leuco dye> 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrabromophthalide 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide 3,3- Bis- [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide

<Others> 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide 3,3-bis (1-ethyl-2-methylindole-3
-Yl) phthalide 3,6-bis (diethylamino) fluoran-γ- (3
'-Nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (4
'-Nitro) anilinolactam 1,1-bis- [2', 2 ', 2 ", 2" -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-dinitrileethane 1,1-bis- [2 ', 2', 2 ", 2" -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2-
β-naphthoylethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-Diacetylethane bis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

In the present invention, a conventionally known color developer for coloring the dye precursor can be used in accordance with the heat resistance characteristic with respect to the target thermal environment, as long as the desired effect on the above-mentioned problem is not impaired. . However, it is desirable to add an extremely small amount, and the amount of the conventionally known color developer is about 0.01 to 0.9 part relative to the compound represented by the general formula (1). When producing a heat-sensitive recording medium having extremely excellent heat resistance, it is better to avoid using a conventionally known color developer. Examples of such a developer include bisphenol A described in JP-A-3-207688 and JP-A-5-24366.
4-hydroxybenzoic acid esters, 4-hydroxyphthalic acid diesters, phthalic acid monoesters, bis-
(Hydroxyphenyl) sulfides, 4-hydroxyphenylarylsulfones, 4-hydroxyphenylarylsulfonates, 1,3-di [2- (hydroxyphenyl) -2-propyl] -benzenes, 4-hydroxybenzoyloxy Benzoic acid esters and bisphenol sulfones are exemplified.

In the present invention, conventionally known sensitizers can be used as long as the desired effects on the above-mentioned objects are not impaired. When manufacturing a heat-sensitive recording material having extremely excellent heat resistance, it is generally better not to use a sensitizer, but it is necessary to add an appropriate amount of the sensitizer according to the heat-resistant temperature characteristics of the target thermal environment. Can be. Examples of such a sensitizer include stearic acid amide, palmitic acid amide, ethylenebisamide, montanic acid wax, polyethylene wax, 1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane,
Dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methylbenzyl) oxalate, dibenzyl terephthalate, benzyl p-benzyloxybenzoate,
Di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, o-xylerin-bis- (phenyl ether), 4- (m- Examples thereof include, but are not particularly limited to, methylphenoxymethyl) biphenyl. These sensitizers may be used alone or in combination of two or more.

As the binder used in the present invention, completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol Modified polyvinyl alcohol such as alcohol, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, cellulose derivatives such as acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide , Polyacrylate, polyvinyl butyral, polystyrene and copolymers thereof, polyamide resin, silicone Butter, petroleum resins, terpene resins, ketone resins, and coumarone resins. These polymeric substances include water, alcohol, ketones, esters,
In addition to being used by dissolving in a solvent such as a hydrocarbon, it can be used in a state of being emulsified or dispersed in water or another medium in the form of a paste, and used in combination depending on required quality.

Further, in the present invention, p-nitrobenzoic acid metal salts (Ca, Zn), which are known stabilizers exhibiting an oil resistance effect of a recorded image and the like, as long as the desired effects on the above-mentioned problems are not impaired, Alternatively, phthalic acid monobenzyl ester metal salt (Ca, Zn) can be added. Methylolated fatty acid amides described in Japanese Patent Application No. 7-313910 may be added. Fillers that can be used in the present invention include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, zinc oxide, aluminum hydroxide, polystyrene resin, urea-formalin resin, and styrene-methacrylic acid. Examples thereof include a polymer, a styrene-butadiene copolymer, and an inorganic or organic filler such as a hollow plastic pigment. In addition, release agents such as fatty acid metal salts,
Lubricants such as waxes, benzophenone-based and triazole-based UV absorbers, water-proofing agents such as glyoxal,
Dispersants, defoamers, antioxidants, fluorescent dyes and the like can be used.

As the support, paper, synthetic paper, plastic film, non-woven fabric, metal foil and the like can be used, or a composite sheet combining these can be used. The amounts of the dye precursor and the developer used in the thermosensitive recording medium of the present invention, the amount of the polyurea compound, and the types and amounts of other various components are determined according to the required performance and recording suitability, and are particularly limited. Although not particularly described, usually, developers 1 to 8 represented by the general formula (1) are used for 1 part of the dye precursor.
Parts, 0.01 to 40 parts of a polyurea compound and 1 to 20 parts of a filler, and the binder is suitably used in an amount of 10 to 25% based on the total solid content.

The developer, the dye precursor and, if necessary, the materials to be added are pulverized by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifying apparatus to a particle size of several microns or less, and the binder and Various coating materials are added according to the purpose to form a coating liquid.
Examples of the coating method include hand coating, size press coater method, roll coater method, air knife coater method, blend coater method, flow coater method, comma direct method, gravure direct method, gravure reverse method, reverse roll coater method and the like. . After spraying, spraying or dipping, drying may be performed.

The thermosensitive recording medium of the present invention further comprises:
An overcoat layer of a polymer substance or the like can be provided on the heat-sensitive recording layer for the purpose of enhancing the storage stability. Further, an undercoat layer containing an organic filler or an inorganic filler can be provided between the recording layer and the support for the purpose of enhancing the storage stability and sensitivity. The thermosensitive recording medium of the present invention can be a thermosensitive recording medium capable of optical recording by incorporating a light absorbing agent which absorbs light and converts it into heat in the thermosensitive recording layer or the like. As the light absorber for converting light to heat used in the recording medium of the present invention, any substance may be used as long as it absorbs the emission wavelength of various light sources, and various dyes, various pigments, near-infrared absorbers and the like can be used, There is no particular limitation.

Further, the heat-sensitive recording medium of the present invention has excellent heat resistance and extremely high thermal stability of ground color, so that a strong protective film can be provided by heat lamination of a plastic film. Therefore, before or after recording by heat or light, it is possible to easily produce a card protected by a plastic film and having excellent heat resistance and various stability by using a plastic film for thermal lamination and a commercially available laminator. Can be. Examples of the base material of the plastic film for heat lamination include polyethylene terephthalate (PET) and polypropylene (PP). Examples of the heat sealant for the plastic film for heat lamination include low-density polyethylene and ethylene / vinyl acetate. A thermoplastic resin such as a copolymer (EVA), an ethylene / ethyl acrylate copolymer (EEA), an ethylene / methyl methacrylate copolymer (EMAA), and an ethylene / methacrylic acid copolymer (EMAA) can be used.

In addition, the heat-sensitive recording medium of the present invention can be subjected to extrusion coating treatment using an extrusion coating resin that can be subjected to extrusion treatment. Examples of the resin for extrusion coating include polypropylene (PP), polyethylene terephthalate (PET), and the like, in addition to various thermoplastic resins useful as the heat sealant. Also,
Since the heat-sensitive recording medium of the present invention has excellent heat resistance, it does not develop ground color even when it comes into contact with the toner heat fixing portion of an electrophotographic copying machine. Therefore, it can be used as a paper for an electrophotographic copying machine. Heat recording is also possible before or after toner recording by an electrophotographic copying machine.

[0061]

【Example】

<< Synthesis of Polyurea Compound >> [Synthesis Example 1] Synthesis of polyurea compound (a01) using MDI and 4,4'-diaminodiphenylmethane 3.0 g of 4,4'-diaminodiphenylmethane was dissolved in 20 ml of anhydrous acetone. Here, under nitrogen atmosphere, M
A solution of 3.75 g of DI dissolved in 20 ml of anhydrous acetone was added dropwise. A white precipitate formed during the addition. The mixture was stirred at room temperature for 2 hours. After the completion of the reaction, the reaction solution was poured into 500 ml of methanol, and the precipitate was separated by filtration, washed with acetone, and dried under reduced pressure to give 6.22 g of a white solid (a01) (yield: 92).
%)Obtained. This was heated and melted at a temperature equal to or higher than the decomposition point or the melting point, attached to a glass rod and pulled up, and it was confirmed whether or not it exhibited a stringy stretchability. The viscosity of this compound was adjusted to a concentration of 0.2 g / dl in 95% sulfuric acid, and measured at 25 ° C. using a Canon-Fenske viscometer (manufactured by Shibata Scientific Instruments, JIS K2283). did. In the following synthesis examples, spinnability and viscosity were examined in the same manner. <Decomposition point> 300 ° C or higher <IR spectrum> (KBr tablet method, cm ~ ¹ ) 3306,3019,1649,1595,1540,1508,1407,1304,1229,1199,
1178,810,501 <Spinnability> None <Viscosity> 19.9mPa · s

Synthesis Example 2 Synthesis of polyurea compound (a03) using MDI and 1,6-hexamethylenediamine 1.86 g of 1,6-hexamethylenediamine was dissolved in 40 ml of dimethylacetamide. Under nitrogen atmosphere, 4.00 g of MDI was added to 40 ml of dimethylacetamide.
Was added dropwise. A white precipitate formed during the addition. The mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction solution was poured into 500 ml of methanol, and the precipitate was separated by filtration, washed with acetone, and dried under reduced pressure to obtain 4.6 of a white solid (a03).
5 g (79% yield) was obtained. <Decomposition point> 260-270 ° C <IR spectrum> (KBr tablet method, cm ~ ¹ ) 3314,2929,2851,1639,1596,1541,1510,1411,1307,1236 <Stringiness> Yes <Viscosity> 20 .3mPa · s

[Synthesis Example 3] 2,4-TDI and 4,4 '
-Polyurea compound (a) with diaminodiphenylmethane
Synthesis of 06) 3.42 g of 4,4′-diaminodiphenylmethane was dissolved in 20 ml of anhydrous acetone. Here under a nitrogen atmosphere,
A solution obtained by dissolving 2.47 ml of 2,4-TDI in 20 ml of anhydrous acetone was added dropwise. Immediately after the dropwise addition, a white precipitate was formed. The mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction solution was poured into 500 ml of methanol, and the precipitate was separated by filtration, washed with acetone, and dried under reduced pressure to obtain a white solid (a06).
14 g (96% yield) was obtained. <Decomposition point> 300 ° C or higher <IR spectrum> (KBr tablet method, cm ~ ¹ ) 3293,2272,1645,1596,1540,1510,1409,1304,1218,1203,
810,662,507 <Spinnability> Yes <Viscosity> 20.1mPa · s

Synthesis Example 4 2,4-TDI and 1,6-
Polyurea compound with hexamethylenediamine (a1
Synthesis of 5) 1.67 g of 1,6-hexamethylenediamine was dissolved in 40 ml of dimethylformamide. Under a nitrogen atmosphere, a solution of 3.29 ml of 2,4-TDI dissolved in 40 ml of dimethylformamide was added dropwise thereto. Immediately after the dropwise addition, a white precipitate was formed. The mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction solution was poured into 500 ml of methanol, and the precipitate was separated by filtration, washed with acetone, and dried under reduced pressure to obtain a white solid (a
5.41 g (yield 81%) of 15) were obtained. <Decomposition point> 230-245 ° C <IR spectrum> (KBr tablet method, cm ~ ¹ ) 3326,2930,2856,1633,1546,1446,1413,1215,1011,649,5
91 <Spinnability> Yes <Viscosity> 20.7 mPa · s

Synthesis Example 5 2,6-TDI and 1,6-
Polyurea compound with hexamethylenediamine (a2
Synthesis of 1) 2.67 g of 1,6-hexamethylenediamine was dissolved in 40 ml of dimethylformamide. Under a nitrogen atmosphere, a solution prepared by dissolving 4.00 g of 2,6-TDI in 40 ml of dimethylformamide was added dropwise thereto. Immediately after the dropwise addition, a white precipitate was formed. The mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction solution was poured into 500 ml of methanol, the precipitate was separated by filtration, washed with acetone, and dried under reduced pressure to give a white solid (a2
6.34 g (yield 95%) of 1) was obtained. <Decomposition point> 250 ° C or higher <IR spectrum> (KBr tablet method, cm ~ ¹ ) 3320,2930,2857,1636,1558,1472,1438,1294,1241,1066,
783,668 <Spinnability> Yes <Viscosity> 20.8mPa · s

<< Production of Thermosensitive Recording Material; Examples 1 to 17,
Comparative Examples 1 to 3 >> The thermosensitive recording medium of the present invention will be described below with reference to examples. In the description, parts and% indicate parts by weight and% by weight, respectively. Various solutions, dispersions, or coating solutions were prepared as follows.

[Examples 1 to 6] In Examples 1 to 6, compounds A-1 and A-1 were used as color developers in the heat-sensitive recording material of the present invention.
0, A-13, A-19, A-40 and B-5, 3-diethylamino-6-methyl-7-anilinofluoran (hereinafter referred to as ODB) as a dye precursor, and a polyurea compound (a03 ). A developer dispersion (solution A), a dye precursor dispersion (solution B), and a methylolated fatty acid amide dispersion (formula C) of the general formula (2) having the following composition are separately averaged in a sand grinder. Wet grinding was performed until the diameter was 1 micron. Solution A (Developer Dispersion) Developer of General Formula (1) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Solution B (Dye precursor dispersion) 3-diethylamino-6 -Methyl-7-anilinofluoran (ODB) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts Liquid C (polyurea compound dispersion) Compound (a03) 4.0 parts 10% polyvinyl alcohol Aqueous alcohol solution 18.8 parts Water 11.2 parts Next, the dispersion liquid was mixed at the following ratio to obtain a coating liquid for the recording layer. Recording layer coating liquid A liquid (developer dispersion liquid) 36.0 parts B liquid (dye precursor dispersion liquid) 9.2 parts C liquid (polyurea compound (a03) dispersion liquid) 34.0 parts Kaolin clay (50) % Dispersion) 12.0 parts Then, the coating liquid for the recording layer was applied to one side of the support (60 g / m ² base paper) and then dried, and the sheet was smoothed with a super calendar at a smoothness of 500 to 600 seconds. To obtain a recording layer having a coating amount of 6.0 g / m ² .

Examples 7 to 10 In Examples 7 to 10, compounds A-10 were used as a developer, the following dye precursors other than ODB were used as dye precursors, and (a) was used as a polyurea compound.
03) This is an example of use. (Dye precursor) ODB-2; 3-dibutylamino-6-methyl-7-anilinofluoran PSD-170; 3-pyrrolidino-6-methyl-7-anilinofluoran BLACK100; 3-diethylamino-7- (M-trifluoromethylanilino) fluoran CVL; 3,3-bis (p-dimethylaminophenyl)
-6-Dimethylaminophthalide A developer dispersion of Compound A-10 and a dispersion of polyurea compound (a03) were treated in the same manner as in Examples 1 to 6.
The dispersion liquids (D liquids) of the dye precursors other than ODB were separately wet-ground by a sand grinder until the average particle diameter became 1 μm. Solution D (Dye precursor dispersion other than ODB) The above dye precursor 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts Then, the dispersion liquid is mixed and stirred at the following ratios, and then coated. Was prepared. Solution A (Developer [Compound (A-10)] dispersion 36.0 parts Solution D (dye precursor dispersion other than ODB) 9.2 parts Solution C (polyurea compound a03 dispersion) 34.0 parts Kaolin clay (50% dispersion) 12.0 parts Next, a recording layer coating liquid was applied to one side of a support (60 g / m ² base paper), and then dried. Processing was performed for 500 to 600 seconds to obtain a recording layer having a coating amount of 6.0 g / m ² .

Embodiments 11 to 14 Embodiments 11 to 14
Is a compound A-10 as a developer and O as a dye precursor
DB, compounds (a01) and (a0) as polyurea compounds
6), (a15), or (a21). A developer dispersion of Compound A-10 and an ODB dispersion were treated in the same manner as in Examples 1 to 6. The polyurea compound dispersion was treated in the same manner as the liquid C to obtain a dispersion E. Next, the dispersion liquid was mixed and stirred at the following ratio to prepare a coating liquid. Solution A (developer [compound (A-10)] dispersion 36.0 parts Solution B (dye precursor [ODB] dispersion) 9.2 parts Solution E (various polyurea compound dispersions) 34.0 parts Kaolin clay (50% dispersion) 12.0 parts Next, a recording layer coating liquid was applied to one side of a support (60 g / m ² base paper), and then dried. Processing was performed for 500 to 600 seconds to obtain a recording layer having a coating amount of 6.0 g / m ² .

Example 15 Example 15 is an example in which A-1 and A-10 are used as color developers, ODB is used as a dye precursor, and compound (a03) is used as a polyurea compound. Compounds A-1 and A-1 in the same manner as in Examples 1 to 6.
0, a developer dispersion, an ODB dispersion, and a compound (a03) dispersion. Next, the dispersion liquid was mixed and stirred at the following ratio to prepare a coating liquid. Liquid A (developer [compound (A-1)] dispersion 18.0 parts Liquid A (developer [compound (A-10)] dispersion 18.0 parts Liquid B (dye precursor [ODB] dispersion) Liquid) 9.2 parts Liquid C (polyurea compound (a03) dispersion) 34.0 parts Kaolin clay (50% dispersion) 12.0 parts Then, the recording layer coating liquid was applied to a support (60 g / m ² base). After coating on one side of paper, the sheet was dried, and the sheet was treated with a super calender so that the smoothness was 500 to 600 seconds, to obtain a recording layer having a coating amount of 6.0 g / m ² .

Example 16 In Example 16, A-10 was used as a developer, and ODB and PSD-17 were used as dye precursors.
0 is an example using compound (a03) as the polyurea compound. Compound A-10 in the same manner as in Examples 1 to 10
Developer dispersion, ODB and PSD-170 dispersion,
The compound (a03) dispersion was treated. Next, the dispersion liquid was mixed and stirred at the following ratio to prepare a coating liquid. Solution A (developer [compound (A-10)] dispersion 36.0 parts Solution B (dye precursor [ODB] dispersion) 4.6 parts Solution D (dye precursor [PSD-170] 4.6) Part C liquid (polyurea compound (a03) dispersion) 34.0 parts Kaolin clay (50% dispersion) 12.0 parts Then, the recording layer coating liquid was applied to one surface of a support (60 g / m ² base paper). After the application, the sheet was dried, and the sheet was treated with a super calendar so that the smoothness became 500 to 600 seconds, to obtain a recording layer having an application amount of 6.0 g / m ² .

Example 17 Example 17 is an example using A-10 as a developer, ODB as a dye precursor, and compounds (a03) and (a15) as polyurea compounds. In the same manner as in Examples 1 to 14, a developer dispersion of Compound A-10, a dispersion of ODB, and a dispersion of Compounds (a03) and (a15) were treated. Next, the dispersion liquid was mixed and stirred at the following ratio to prepare a coating liquid. 16. Liquid A (developer [compound (A-10)] dispersion 36.0 parts Liquid B (dye precursor [ODB] dispersion) 9.2 parts Liquid C (polyurea compound (a03) dispersion) 0 part E liquid (polyurea compound (a15) dispersion) 17.0 parts kaolin clay (50% dispersion) 12.0 parts Then, the recording layer coating liquid was applied to one side of a support (60 g / m ² base paper). After drying, the sheet was treated with a super calender so as to have a smoothness of 500 to 600 seconds to obtain a recording layer having a coating amount of 6.0 g / m ² .

[Comparative Example 1] The same processing as in Example 2 was performed except that the solution C was omitted. [Comparative Example 2] The dye precursor was replaced with OD except for the solution C of Example 4.
Except having changed to B2, the same process was performed.

[Comparative Example 3] A dispersion of bisphenol A (hereinafter referred to as BPA) as a color developer of a comparative example having the following composition (F
Liquid) was wet-ground with a sand grinder until the average particle size became 1 micron. Solution F (BPA dispersion) BPA 6.0 parts 10% aqueous solution of polyvinyl alcohol 18.8 parts Water 11.2 parts Next, the dispersion of the solution F and the solution B is mixed in the following ratio, and the coating of the recording layer is performed. Liquid. Recording layer coating liquid F liquid (BPA dispersion liquid) 36.0 parts Liquid B (dye precursor dispersion liquid) 9.2 parts Kaolin clay (50% dispersion liquid) 12.0 parts Then, the recording layer coating liquid was applied to the support ( 60 g / m ² of base paper), and then dried. This sheet was treated with a super calender so that the smoothness was 500 to 600 seconds, and the recording layer having a coating amount of 6.0 g / m ² was used. I got

<< Evaluation of Thermosensitive Recording Material; Examples 1 to 17,
Comparative Examples 1 to 3 >> The thermal recording materials of Examples 1 to 17 and Comparative Examples 1 to 3 were subjected to a thermal recording test (recording density, ground color density) and a plasticizer resistance test. Table 1 shows the thermosensitive recording materials of Examples and Comparative Examples, and Table 2 shows the results of the respective tests. Each test in Table 2 was performed by the following method.

[Thermal Recording Test (Dynamic Color Density)] Personal Word Processor Rupo-90FII (manufactured by Toshiba Corporation)
The thermal recording was performed on the thermal recording media of Examples 1 to 17 and Comparative Examples 1 to 3 at the maximum applied energy (the same conditions were used for the thermal recording described below). The recording density of the recording portion was measured by a Macbeth densitometer (RD-914, using an amber filter, the same conditions hereinafter). In the heat-sensitive recording materials of Examples 1 to 17 using the compound of the present invention as a color developer, a sufficient recording density was obtained by a printer.

[Plasticizer resistance test] A vinyl chloride wrap (High Wrap KMA manufactured by Mitsui Toatsu) was wrapped around a paper tube in a single layer, and a thermosensitive recording medium recorded by the printer was attached thereon, and further a vinyl chloride wrap was further placed thereon. Was wound three times and left at 40 ° C. for 4 hours, and then the Macbeth densities of the image area and the ground color area were measured. In the heat-sensitive recording materials of Examples 1 to 17 of the present invention, the recorded image almost remained, and no coloring of the ground color portion occurred.

[Ground Thermal Stability Test] Using a gear type aging tester (Toyo Seiki Seisaku-sho, Ltd.) at a test temperature of 11
A heat resistance test at 0 ° C. (2 hours) was performed on the thermosensitive recording media of Examples 1 to 17 and Comparative Examples 1 to 3. After the heat resistance test, the density of the ground color was measured with a Macbeth densitometer. In this case, the smaller the value of the Macbeth density, the less the ground color is developed, and the higher the thermal stability of the ground color. The heat-sensitive recording materials of Examples 1 to 17 using the compound of the present invention as a color developer had a value of 0.1 or less even at 110 ° C, and showed good thermal stability.

[0079]

[Table 1]

[0080]

[Table 2]

[0081]

The heat-sensitive recording material of the present invention has high heat resistance and extremely strong plasticizer resistance in the recorded image area and the ground color area. The effects of the present invention can be summarized as follows. (1) Even if it comes into contact with a plasticizer contained in a wrap film or the like that is used daily, the recorded image does not lose color and is highly practical, and the coloring of the ground color portion does not occur, so that the appearance is impaired. There is no. (2) The heat-sensitive recording material of the present invention can be heated in a microwave oven or the like while being attached to a wrap film, or can be subjected to high-temperature sterilization. is there. (3) The thermosensitive recording medium of the present invention has the general formula (1) in the recording layer.
Since it contains a developer represented by and a polyurea compound, thermal recording can be performed by at least one coating,
In addition, since it is possible to form a layer having heat resistance and plasticizer resistance, it is excellent in economical efficiency.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Reiko Sato 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Inside Japan Paper Products Co., Ltd. (72) Inventor Reiji Ohashi 5-2-11-1 Oji, Kita-ku, Tokyo No. Nippon Paper Industries Central Research Laboratory (72) Inventor Tomoyuki Nakano 5-21-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Central Research Laboratory

Claims (3)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing, as a main component, a colorless or pale color dye precursor and a color developer which reacts with the dye precursor to form a color. The developer is at least one compound represented by the following general formula (1), and at least one compound is contained in the recording layer.
A heat-sensitive recording material comprising a kind of polyurea compound. Embedded image (Wherein, X represents an oxygen atom or a sulfur atom;
Is an unsubstituted or substituted phenyl group, naphthyl group, aralkyl group, lower alkyl group having 1 to 6 carbon atoms, cycloalkyl group having 3 to 6 carbon atoms, or 2 to 6 carbon atoms.
Represents a lower alkenyl group. Z represents a lower alkyl group having 1 to 6 carbon atoms or an electron-withdrawing group. n represents an integer of 0 to 4, and p represents an integer of 1 to 5. Where n + p ≦ 5
Shall be satisfied. ) 2. The thermosensitive recording medium according to claim 1, wherein the recording layer contains a polyurea compound having a repeating unit represented by the following general formula (2). Embedded image (However, A ¹ represents a divalent group.) 3. The heat-sensitive recording material according to claim 1, wherein the recording layer contains a polyurea compound having a repeating unit represented by the following general formula (3). Embedded image (However, ^one of R ¹ and R ² represents a hydrogen atom and the other represents a methyl group. A ² represents a divalent group.)