JPH08216526A - Thermal recording material - Google Patents

Abstract

PURPOSE: To obtain a thermal recording material excellent in ground color stability by adding at least one urea compd. represented by a specific formula to a thermal color forming layer as a coupler. CONSTITUTION: As a coupler added to the thermal color forming layer of a thermal recording material, a monourea compd. having an arylureido structure [HOOC-Ar-NH-C(=O)-NH-] having a carboxyl group in its molecule represented by formula (R is a phenyl group, a 7-10C alkylphenyl group, a 7-10C alkoxyphenyl group, a tri-halogenated methylphenyl group or a halogenated phenyl group and X is a 1-6C alkyl group or a 1-4C alkoxy group) is used. By using this monourea comd., the change in a ground color is not substantially generated at environment temp. of 120-135 deg.C and recording of image density worthy of practical use can be obtained by a thermal head.

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 excellent in stability of a background color portion (white paper portion).

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is prepared by grinding and dispersing a colorless or light-colored electron-donating colorless dye and a color developing agent such as a phenolic compound into fine particles, and then mixing the two. A coating liquid obtained by adding a binder, a filler, a sensitivity improver, a lubricant, and other auxiliaries to a support such as paper, synthetic paper, film, plastic, etc.,
A visible record is obtained by color development by an instant chemical reaction caused by heating with a thermal head, hot stamp, laser light or the like.

The thermosensitive recording medium is applied to a wide range of fields such as a measuring recorder, a computer terminal printer, a facsimile, an automatic ticket vending machine and a bar code label. However, with the recent diversification of recording devices for thermal recording media and the progress of higher performance, the quality required for thermal recording media has become higher and more difficult. For example, from the viewpoint of speeding up recording, there is a demand for a heat-sensitive recording material that can obtain a color image with a high recording density even with a smaller heat energy. On the other hand, from the viewpoint of storage stability of the recording material, there is a demand for a thermal recording material having excellent light resistance, oil resistance, water resistance, solvent resistance and the like.

With the spread of plain paper recording systems such as electrophotographic systems and ink jet systems, thermal recording systems are often compared with these plain paper recording systems. Therefore, for example, the stability of the recording portion (image) of the thermal recording material or the stability of the non-recording portion before and after recording (called the background color portion or the blank sheet portion) (hereinafter referred to as background color stability) , Etc.) is required to approach the same quality as the plain paper recording method. Among them, particularly, the thermal recording material is required to have background color stability against heat and solvent (hereinafter referred to as background color heat resistance and background color solvent resistance, respectively). In other words, it can be said that the recording body is, so to speak, “heat-sensitive” only during recording and is “non-heat-sensitive” except during recording.

Regarding the background color stability of the thermal recording material, for example,
Japanese Patent Laid-Open No. 4-353490 discloses a heat-sensitive recording material having relatively good ground color stability even under a high temperature condition of about 90 ° C. This heat-sensitive recording material is characterized by containing a 4-hydroxydiphenylsulfone compound and a metal salt of phosphate.

[0006]

The background color stability of the thermosensitive recording medium disclosed in Japanese Patent Laid-Open No. 4-353490 is 95% in a dryer.
When processed at 5 ℃ for 5 hours, the Macbeth density of the background color is about 0.11 and shows a considerable stability, but it is still insufficient in terms of the stability of the background color at a temperature higher than that, for example, 120 ℃. there were. Therefore, it is an object of the present invention to provide a thermosensitive recording medium excellent in ground color stability.

[0007]

The above problems were solved by a thermosensitive recording medium using a monourea compound having a carboxyl group as a developer.

JP-A-53-140043 and JP-A-57-87993
JP-A-57-82787, JP-A-59-67083 and the like have been known as a conventional developer such as a urea compound and a phenol type developer (bisphenol A, bisphenol S, etc.). A thermosensitive recording medium is disclosed in which a phenol compound) is used in combination. In these publications, the urea compound has only a limited number of carbon atoms and is basically used only as a melting point adjusting agent for a phenol-based developer. However, a heat-sensitive recording material containing a urea compound and a phenol-based color developer in combination could not obtain sufficient heat resistance against background color.

Patents using a specific monourea compound in a thermal recording material are disclosed in JP-A-58-211496, JP-A-59-184694 and JP-A-61-211085. There is. The monourea compound used in these publications is a urea compound in which only one amino group portion of urea is substituted. However, a heat-sensitive recording material using this urea compound alone as a color developer also did not show sufficient background color heat resistance. Also in these publications,
It was used in combination with a phenol-based developer, and with this combination, good ground color heat resistance could not be obtained.

Further, a heat-sensitive recording material using a bisurea compound is disclosed in Japanese Patent Application Laid-Open No. 5-131752, Japanese Patent Application Laid-Open No. 5-147357,
It is disclosed in Japanese Patent Application Laid-Open Nos. 5-148220, 6-227142, and the like. JP-A-5-131752, JP-A-5-147357
The bisurea compound described in JP-A No. 5-148220 or JP-A No. 5-148220 has a structure in which a sulfonyl group is adjacent to a urea structure (Ar—SO ₂ —NH—C (═O) —NH—)
It is characterized by having individual pieces. However, even these urea compounds have insufficient heat resistance under high temperature conditions of 120 ° C or higher. On the other hand, the bisurea compound described in JP-A-6-227142 is a compound in which two arylureido structures (Ar-NH-C (= O) -NH-) are linked by a diphenyl derivative. In this publication, the aryl group having an arylureido structure is exemplified by halogen substitution and unsubstituted, but there is no description about the case of having a carboxyl group (—COOH). Although this urea compound can obtain heat resistance under a high temperature condition of 120 ° C. or higher, it has a drawback that the coloring sensitivity is insufficient.

The present inventors have found that a heat-sensitive recording material excellent in ground color stability can be obtained by using a specific monourea compound (monourea compound having a carboxyl group) as a developer. The present invention has been completed and the present invention has been completed. That is, the present invention provides a thermosensitive recording material having a thermosensitive color developing layer containing a colorless or light-colored dye precursor and a developer which reacts when heated to develop the color of the dye precursor. It relates to a monourea compound represented by the formula (1), wherein the thermosensitive coloring layer contains at least one kind of the monourea compound.

[0012]

Embedded image (Here, R is a phenyl group, an alkylphenyl group having 7 to 10 carbon atoms, an alkoxyphenyl group having 7 to 10 carbon atoms, a trihalogenated methylphenyl group, a halogenated phenyl group, and 7 to 10 carbon atoms. Aralkyl group of 10 to 12 carbon atoms
Represents an alkenylaralkyl group, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group, or a hydrogen atom. X
Is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a trihalogenated methyl group, a nitro group,
Represents a halogen atom or a hydrogen atom. )

The monourea compound represented by the general formula (1) used in the present invention is a monourea having an arylureido structure (HOOC-Ar-NH-C (= O) -NH-) having a carboxy group in the molecule. It is a compound. Regarding the substituent (R) of the monourea compound represented by the general formula (1), the melting point of the monourea compound, the decomposition temperature, the solubility in a solvent, etc.
It should be appropriately selected depending on the performance of the manufactured thermal recording material (recording density, stability of recording area, ground color stability, etc.), or ease of synthesis (availability of raw materials, reaction yield, etc.). There is no particular limitation. However, from the viewpoint of recording density, the substituent (R) of the monourea compound represented by the general formula (1) is preferably a substituted or unsubstituted phenyl group, and among them, an electron-withdrawing group is preferable. The case where it is substituted (that is, in the case of a trihalogenated methylphenyl group and a halogenated phenyl group) and the case where it is unsubstituted (in the case of a phenyl group) are more preferable. From the viewpoint of cost, as a matter of course, a phenyl group is preferable.

On the other hand, considering the arylureido structure having a carboxy group, the substituent (X) on the aromatic ring of the arylureido structure portion of the monourea compound represented by the general formula (1) is also the melting point of the monourea compound, It should be appropriately selected depending on the decomposition temperature, the solubility in a solvent, etc., or the performance (recording density, stability of recording area, background color stability, etc.) of the thermosensitive recording medium to be manufactured, and is not particularly limited. is not. However, from the viewpoint of recording density, higher recording density can be obtained when the substituent (X) on the aromatic ring is a hydrogen atom (that is, when the substituent is unsubstituted), or when electron withdrawing is performed. It is more preferable that it is a functional group (alkyl halide group, nitro group, halogen atom). Considering recording density, ground color stability, economy (cost), etc. comprehensively, aromatic ring substituent (X)
Is a hydrogen atom, which is the most well-balanced and most preferable.

Regarding the carboxyl group of the carboxyarylureido structure portion of the monourea compound represented by the general formula (1), the hydroxyl group is
It is more preferably located at the meta position or the para position with respect to the ureido structure.

The monourea compound represented by the general formula (1) includes, for example, (1) a reaction of an aminobenzoic acid derivative with a monoisocyanate compound (reaction of the formula (A)), (2) an isocyanate of benzoic acid. It can be easily synthesized by a reaction between the derivative and monoamines (reaction of formula (a)).

[0017]

Embedded image

Among these reactions, the reaction of the formula (a) is the most advantageous method from the viewpoints of availability of raw materials, simplicity of reaction and the like. In the case of the reaction of the formula (a), for example, as aminobenzoic acid derivatives, anthranilic acid, m-aminobenzoic acid, p-aminobenzoic acid, 6-amino-o-toluic acid, 3-amino-p-toluic acid, 4-amino-2-n-butylbenzoic acid, 4-amino-2-tert-butylbenzoic acid, 4-amino-2
-n-hexylbenzoic acid, 2-amino-5-methoxybenzoic acid, 5-amino-2-methoxybenzoic acid, 5-amino-2-n-butoxybenzoic acid, 4-nitroanthranilic acid, 5-amino-2
-Nitrobenzoic acid, 4-chloroanthranilic acid, 5-chloroanthranilic acid, 3-amino-4-chlorobenzoic acid, 4-amino-2-chlorobenzoic acid, 2-amino-5-bromobenzoic acid,
4-amino-2-trifluoromethylbenzoic acid and the like can be mentioned. On the other hand, monoisocyanate compounds include phenyl isocyanate, p-tolyl isocyanate, and 4-isocyanate.
Methoxyphenyl, o-trifluoromethylphenyl isocyanate, m-trifluoromethylphenyl isocyanate, p-fluorophenyl isocyanate, p-isocyanate
Chlorophenyl, benzyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate, phenylpropyl isocyanate, methyl isocyanate, ethyl isocyanate, n-propyl isocyanate, iso-propyl isocyanate, n-butyl isocyanate, isocyanate Examples thereof include sec-butyl acid, tert-butyl isocyanate, n-hexyl isocyanate, and cyclohexyl isocyanate, which can be selected by arbitrarily combining them.

The following compounds may be mentioned as specific examples of the monourea compound represented by the general formula (1).

[0020]

[Chemical 4]

Embedded image

[0021]

[Chemical 6]

[Chemical 7]

[0022]

Embedded image

[Chemical 9]

[0023]

[Chemical 10]

[Chemical 11]

[0024]

[Chemical 12]

[Chemical 13]

The heat-sensitive recording material using the monourea compound represented by the general formula (1) of the present invention is excellent in ground color stability against heat and solvent. That is, 1
Even when placed in a high temperature environment of 20 ° C. or higher, the ground color of the recording surface (the surface provided with the thermosensitive coloring layer) of the thermosensitive recording material does not substantially change (does not develop color). However, this recording medium is usually
When the high energy of the thermal head of ~ 300 ° C is applied instantaneously, the recording material develops a dark color. Regarding the heat-sensitive recording materials known so far, regarding the heat resistance of the background color, even if a heat block of 120 ° C or higher is applied to the surface of the heat-sensitive recording layer, the color does not develop Therefore, it was unthinkable that the density could be recorded for practical use. Moreover, the material which can do such a thing was not known at all.

Since the thermal recording material of the present invention has high heat resistance, for example, (a) thermal lamination is performed by heat-adhering the recording surface after thermal recording with a plastic film or the like;
(b) To be used as a transfer sheet for electrophotography, to adhere toner to the surface of the thermosensitive recording layer for thermal fixing, or
(c) It is also possible to attach toner to the heat-sensitive recording surface of the heat-sensitively recorded sheet to fix the heat.

Further, the thermosensitive recording medium of the present invention has an advantage that the manufacturing process is very easy to control. That is, conventionally, in the production of a thermosensitive recording medium, the drying step after coating the thermosensitive coloring layer requires very strict temperature control so that the background coloring of the coated surface does not occur, and therefore high speed coating is also limited. was there. However, the thermal recording material of the present invention is
Since the background color does not develop even if hot air is applied, high-temperature drying in the drying process is possible, and the control range of the drying temperature can be greatly expanded, so it is possible to expect a dramatic improvement in productivity. it can.

Further, in the heat-sensitive recording material of the present invention, the monourea compound used does not cause discoloration due to the oil-based ink, probably because the monourea compound has low solubility in an organic solvent. Therefore,
It is also possible to write with an oil-based ink on the surface of the heat-sensitive recording layer of the heat-sensitive recording material. As described above, the monourea compound represented by the general formula (1) is a heat-sensitive recording material excellent in stability of background color (heat resistance, solvent resistance, etc.).

A general method for producing the heat-sensitive recording material of the present invention is to disperse (a) a dye precursor and (b) a urea compound represented by the general formula (1) as a developer with a dispersing function. This is a method in which each is dispersed together with the binder that it has, an auxiliary agent such as a filler and a lubricant is added if necessary to prepare a coating liquid, and the coating liquid is applied onto a support by a usual method and dried.

In the present invention, the monourea compound represented by the general formula (1) may be used alone or in combination of two or more kinds. In addition, for example, Japanese Patent Application No. 5-231105
Specification, Japanese Patent Application No. 5-250328, Japanese Patent Application No. 5-250329, Japanese Patent Application No. 5-311502, Japanese Patent Application No. 5-315023, Japanese Patent Application No. 5-317211 Specification, Japanese Patent Application No. 5-321506, Japanese Patent Application No. 6-100082, Japanese Patent Application No. 6-14310, Japanese Patent Application No. 6-144159, Japanese Patent Application No. 6-144160. It is also possible to use in combination with the urea compounds described in Japanese Patent Application No. 6-164161, Japanese Patent Application No. 6-184285, Japanese Patent Application No. 7-9806, and the like.

In principle, the thermosensitive recording medium of the present invention should not be used in combination with a phenol compound conventionally known as a color developer. When a phenol compound is used, the performance of the heat-sensitive recording material (recordability, heat resistance, solvent resistance, etc.) mainly depends on the phenol compound. Therefore, the heat-sensitive recording material used in combination with the phenol compound cannot obtain sufficient heat resistance of the background color. However, as long as the performance such as the ground color stability (heat resistance, solvent resistance, etc.) of the heat-sensitive recording material to be produced is not impaired, a conventionally known developer (for example, bisphenol) for coloring the dye precursor is developed. A, bisphenol S, benzyl 4-hydroxybenzoate, 4-hydroxy-4′-isopropoxydiphenyl sulfone, etc.) may be used together in a small amount.

As the dye precursor used in the heat-sensitive recording material of the present invention, those conventionally known in the field of heat-sensitive recording can be used, and although not particularly limited, triphenylmethane leuco dyes, Fluoran-based leuco dyes and fluorene-based leuco dyes are preferred. Hereinafter, typical dye precursors will be exemplified.

3,3-bis (4'-dimethylaminophenyl)
-6-Dimethylaminophthalide (also known as crystal violet lactone (CVL)) 3,3-bis (4'-dimethylaminophenyl) -6-pyrrolidylphthalide 3,3-bis (4'-dimethylamino Phenyl) phthalide
(Alias: Malachite Green Lactone (MGL)) Tris [4- (dimethylamino) phenyl] methane (Alias: Leuco Crystal Violet (LCV)) 3-Dimethylamino-6-methyl-7- (m-trifluoromethyl) Anilino) fluorane 3-diethylamino-6-methyl-fluorane 3-diethylamino-7-methyl-fluorane 3-diethylamino-7-chloro-fluorane 3-diethylamino-6-methyl-7-chlorofluorane 3-diethylamino-6- Methyl-7-anilinofluorane 3-diethylamino-6-methyl-7-p-methylanilinofluorane 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane 3-diethylamino-6 -Methyl-7- (m-trifluoromethylanilino) fluorane 3-diethylamino-6-methyl-7- (o-chloroanilino) fluorane 3-diethylamino-6-methyl-7- (p-Chloroanilino) fluorane 3-diethylamino-6-methyl-7- (o-fluoroloanilino) fluorane 3-diethylamino-6-methyl-7- (pn-butylanilino)
Fluorane 3-diethylamino-6-methyl-7-n-octylaminofluorane 3-diethylamino-6-chloro-7-anilinofluorane 3-diethylamino-6-ethoxyethyl-7-anilinofluorane 3-diethylamino- Benzo [a] fluorane 3-diethylamino-benzo [c] fluorane 3-diethylamino-6-methyl-7-benzylaminofluorane 3-diethylamino-6-methyl-7-dibenzylaminofluorane 3-diethylamino-7-di (P-Methylbenzyl) aminofluorane 3-diethylamino-6-methyl-7-diphenylmethylaminofluorane 3-diethylamino-7-dinaphthylmethylaminofluorane 10-diethylamino-4-dimethylaminobenzo [a] fluorane 3 -Dibutylamino-7- (o-chloroanilino) fluorane 3-dibutylamino-6-methylfluorane 3-dibutylamino-6- Methyl-7-chlorofluorane 3-dibutylamino-6-methyl-7-anilinofluorane 3-dibutylamino-6-methyl-7-p-methylanilinofluorane 3-dibutylamino-6-methyl-7 -(o, p-Dimethylanilino) fluorane 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3-dibutylamino-6-methyl-7- (o-chloroanilino) fluorane 3 -Dibutylamino-6-methyl-7- (p-chloroanilino) fluorane 3-dibuethylamino-6-methyl-7- (o-fluoroloanilino) fluorane 3-dibuethylamino-6-methyl-7- ( pn-Butylanilino) fluorane 3-dibutylamino-6-methyl-7-n-octylaminofluorane 3-dibutylamino-6-chloro-7-anilinofluorane 3-dibutylamino-6-ethoxyethyl-7-ani Rinofluorane 3-di-n-pentylamino-6-methyl-7-anilino Luoran 3-di-n-pentylamino-6-methyl-7- (o, p-dimethylanilino) fluorane 3-Di-n-pentylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3 -Di-n-pentylamino-6-methyl-7- (o-chloroanilino) fluorane 3-di-n-pentylamino-6-methyl-7- (p-chloroanilino) fluorane 3-di-n-pentylamino-6-methyl -7- (o-Fluoroloanilino) fluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 3-piperidino-6-methyl-7-anilinofluorane 3- (N-methyl-Nn-propyl Amino) -6-methyl-7-anilinofluorane 3- (N-ethyl-Nn-propylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-iso-propylamino) -6-methyl-7-
Anilinofluorane 3- (N-ethyl-Nn-butylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-iso-butylamino) -6-methyl-7-anilino Fluoran 3- (N-ethyl-Nn-hexylamino) -6-methyl-7-p-
Methylanilinofluorane 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (o,
p-Dimethylanilino) fluorane 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (m-
Trifluoromethylanilino) fluorane 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (o-
Chloroanilino) fluorane 3- (N-ethyl-N-iso-amylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-iso-amylamino) -6-chloro-7-anilinoflu Oran 3- (N-ethyl-N-3-methylbutylamino) -6-methyl-7
-Anilinofluoran 3- (N-ethyl-Np-toluidino) -6-methyl-7-anilinofluoran 3- (N-ethyl-Np-toluidino) -6-methyl-7- (p-methylanilino) Fluoran 3- (N-ethyl-Np-toluidino) -6-methyl-7- (o, p-dimethylanilino) fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-
Methyl-7-anilinofluorane 3- (N-cyclohexyl-N-methylamino) -6-methyl-7
-Anilinofluorane 3- (N-cyclohexyl-N-methylamino) -7-anilinofluorane 3- (N-ethyl-N-3-methoxypropylamino) -6-methyl-7-anilinofluorane 3- (N-Ethyl-N-3-ethoxypropylamino) -6-methyl-7-anilinofluorane 2- (4-oxahexyl) -3-dimethylamino-6-methyl
-7- Anilinofluorane 2- (4-oxahexyl) -3-diethylamino-6-methyl
-7- Anilinofluorane 2- (4-oxahexyl) -3-dipropylamino-6-methyl-7-anilinofluorane 3- (4``-aminostilbrudil-4'-amino)- 7,8-Benzofuran 3,6,6'- Tris (dimethylamino) spiro [fluorene
-9,3'-phthalide] 3,6,6'-tris (diethylamino) spiro [fluorene
-9,3'-phthalide] 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-diethylamino-2-n-hexylphenyl) -3- (1-
Ethyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylmethylamino-2-methoxyphenyl) -3- (1-ethyl-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-methylindol-3-yl) phthalide 3,3-bis (2-methyl-1-octylindol-3-yl)
Phthalide 3- (1-Ethyl-2-methylindol-3-yl) -3- (1-
n-Butyl-2-methylindol-3-yl) phthalide 3,7-bis (dimethylamino) -10-benzoylphenothiazine 3,7-bis (dimethylamino) -N- [pN-bis (4,4 '-Dimethylaminophenyl) methylamino] benzoylphenothiazine 3,7-bis (dimethylamino) -N- [pN-bis (4,4'-diethylaminophenyl) methyl] benzoylphenothiazine 3,6-bis (diethylamino) fluorane- γ- (2'-nitro) anilinolactam 3,6-bis (diethylamino) fluorane-γ- (3'-nitro) anilinolactam 3,6-bis (diethylamino) fluorane-γ- (4'-nitro) Anilinolactam 3,6-bis (diethylamino) fluorane-γ-anilinolactam

These dye precursors may be used alone or in admixture of two or more. In the present invention, among these dye precursors, a fluoran dye precursor can be preferably used. Further, in particular, when importance is attached to thermal stability, naturally, a dye precursor having a high melting point and a high decomposition temperature is preferable.

Further, in the heat-sensitive recording material of the present invention, in particular, when heat resistance of the background color is required, it is generally preferable not to use a sensitizer. This is because when a sensitizer is used, the color development temperature depends on the melting point of the sensitizer. However, these may be used alone or in combination depending on the required performance of the manufactured thermal recording material. As the sensitizer used, 2-di (3-methylphenoxy) ethane, p-benzylbiphenyl, β-benzyloxynaphthalene, 1-
Hydroxy-2-naphthoic acid phenyl ester, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, diphenyl carbonate, ditolyl carbonate, 4-biphenyl-p-
Trilyl ether, m-terphenyl, 1,2-diphenoxyethane, 1,2-bis (m-tolyloxy) ethane, 1,5-bis (p-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, shu Examples include acid di (p-methylbenzyl), oxalate di (p-chlorobenzyl), and the like.

As the binder which can be used in the heat-sensitive recording material of the present invention, fully saponified polyvinyl alcohol having a polymerization degree of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol and sulfonic acid are used. Polyvinyl alcohols such as modified polyvinyl alcohol, butyral modified polyvinyl alcohol and other modified polyvinyl alcohols; cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, ethyl cellulose and acetyl cellulose; styrene-maleic anhydride copolymer, styrene -Butadiene copolymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acid ester, polyacrylic acid ester, polyvinyl chloride Butyral, polystyrene,
And synthetic polymers such as copolymers composed of combinations thereof; polyamide resins, silicone resins, petroleum resins,
Resins such as terpene resin, ketone resin and coumarone resin can be exemplified. Among these examples, polyvinyl alcohol-based binder has dispersibility, binder property,
It is also desirable in terms of heat stability of the ground color. These binders are used in a state of being dissolved in a solvent such as water, alcohol, ketone, ester, hydrocarbon, or emulsified in water or other medium, or dispersed in a paste form, and used together depending on the required quality. It is also possible.

The fillers used in the present invention include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, zinc oxide, titanium oxide, zinc hydroxide, aluminum hydroxide, and other inorganic fillers, or polystyrene-based organic fillers. Examples include fillers, styrene / butadiene organic fillers, styrene / acrylic organic fillers, hollow organic fillers, and the like.

In addition to these, a releasing agent such as a fatty acid metal salt, a lubricant such as wax, an ultraviolet absorber of benzophenone type or benzotriazole type, a water resistant agent such as glyoxal, a dispersant, an antifoaming agent, etc. should be used. You can also

The blending amount of the (a) dye precursor of the present invention and (b) the monourea compound represented by the general formula (1), and the types and blending amounts of other various components are required performance and recording. It is determined according to suitability and is not particularly limited, but is usually 1 to 8 parts of monourea compound and 1 to 20 parts of filler to 1 part of the dye precursor, and the binder is 10 to 10 parts in the total solid content. 25% by weight. These materials are pulverized by a crusher such as a ball mill, attritor, or sand grinder, or an appropriate emulsifying device to a particle size of several microns or less, and a binder and various additives depending on the purpose are added to a coating liquid. And A desired thermosensitive recording medium can be obtained by applying the coating liquid to a support.

The support used in the present invention is paper,
Examples thereof include synthetic paper, non-woven fabric, metal foil, plastic film, plastic sheet, and composite sheets obtained by combining these.

Further, in the heat-sensitive recording material of the present invention, an overcoat layer made of a polymeric substance is provided on the heat-sensitive color developing layer for the purpose of enhancing the storage stability of the recording material, or a filler is used for the purpose of enhancing the color developing sensitivity of the recording material. It is also possible to provide an undercoat layer of a polymer substance or the like containing under the thermosensitive coloring layer.

Further, in the heat-sensitive recording material of the present invention, by utilizing high ground color stability, a plastic film can be thermally laminated to provide a transparent and strong protective coating. For example, even after heat-sensitive recording on the heat-sensitive recording material of the present invention, a card having excellent stability such as heat resistance can be easily prepared by using a commercially available simple laminating machine. Examples of the plastic film used in the heat-sensitive recording material of the present invention include low density polyethylene, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer,
Ethylene / methyl methacrylate copolymer, ethylene /
There may be mentioned thermoplastic resins such as methacrylic acid copolymers.

The heat-sensitive recording material of the present invention may have a light-absorbing agent which absorbs light and converts it into heat in its heat-sensitive recording layer. The light absorber is not particularly limited as long as it is a substance that absorbs the emission wavelength of various light sources.

For example, when a light source having a continuous wavelength, a strobe flash or the like is used as a light source for recording, the light absorber is described in JP-A-2-206583 and Japanese Patent Application No. 5-30954. Examples include heating reaction products of thiourea derivatives / copper compounds, graphite described in JP-A-3-86580, copper sulfide, lead sulfide, molybdenum trisulfide, black titanium, carbon black, and the like.

On the other hand, when a semiconductor laser is used as a light source for recording, it is used as a light absorber in JP-A-54-4142.
JP-A-58-94494, JP-A-58-209594, JP-A-2-217287, JP-A-3-73814, etc., polymethine dyes (cyanine dyes),
Azolenium dyes, pyrylium dyes, thiopyrylium dyes, squarylium dyes, croconium dyes, dithiol complexes, mercaptophenol metal complex dyes, mercaptonaphthol metal complex dyes, phthalocyanine dyes, naphthalocyanine dyes, triarylmethane dyes Examples thereof include dyes, immonium dyes, diimmonium dyes, naphthoquinone dyes, anthraquinone dyes, and metal complex dyes. Further, the light absorbers mentioned in the case of the light source having a continuous wavelength can be used as well.

Specifically, for example, Color Chemical Encyclopedia (edited by Organic Synthesis Society, CMC Publishing (1988) p196-2)
00) Table 1 and Chemical Industry (vol.5, 1986, p379-389) Table 3
Near infrared absorbing dyes described, JP-A-61-69991, JP-A-61-69991
61-246391 Publication, US-PATENT: 35570122, US-PATENT: 35
75871, near-infrared absorbing dyes described in US-PATENT: 3637769, 1,1,5,5-tetrakis (p-dimethylaminophenyl)
-3-Methoxy-1,4-pentadiene (or its cation), 1,1,5,5-tetrakis (p-diethylaminophenyl) -3-methoxy-1,4-pentadiene (or its cation), toluene Dithiol nickel complex, 4-tert
-Butyl-1,2-benzenedithiol nickel complex, bisdithiobenzyl nickel complex, bis (4-ethyldithiobenzyl) nickel complex, bis (4-n-propyldithiobenzyl) nickel complex and the like. You may use these light absorbers individually or in mixture of 2 or more types.

These light absorbers are used (a) by simply mixing them in various materials necessary for the heat-sensitive recording material, and (b) JP
As described in 2-217287, etc., in various materials necessary for a thermal recording material, a method in which a light absorber is melt-mixed in advance and dissolved or dispersed, or (c)
The light absorber may be dissolved or dispersed in a solvent in advance in various materials necessary for the heat-sensitive recording material, and the dissolved or dispersed mixture may be used according to a method of using after removing the solvent. Further, the light absorber is a developer, a dye precursor,
It may be co-dispersed (simultaneous mixing dispersion) with a sensitizer, a mixture of a developer and a sensitizer, or a mixture of a dye precursor and a sensitizer.

The heat-sensitive recording material of the present invention does not change its background color stability (heat resistance, solvent resistance, etc.) even if it contains a light absorber. Therefore, even in the case of a heat-sensitive recording material containing a light absorber, toner recording,
Alternatively, heat lamination or the like can be performed.

A heat-sensitive card prepared by heat-laminating a heat-sensitive recording material containing a light-absorbing agent with a plastic film before or after heat-sensitive recording should be recorded using light from above the laminated plastic film. You can also

[0050]

The monourea compound represented by the general formula (1) of the present invention is a color developing agent which is excellent in color forming property and stability in background color against heat and solvent. General formula (1) of the present invention
The clear reason why the monourea compound represented by the formula (3) gives high ground color stability has not yet been clarified.
However, the reason is estimated as follows.

The bisurea compound represented by the general formula (1) has a carboxyl group directly bonded to the aryl group of the carboxyarylureido structure as a site which is considered to have a color developing property (a property of developing a dye precursor). , And two urea structures of carboxyarylureido structure. However, it is believed that the urea structure is mainly involved in the color developing property in both cases. The structure of this urea structure changes according to the conditions as shown in the following formula. Since this change is a phenomenon similar to keto / enol tautomerism, it is referred to as keto-enolization here for convenience.

[0052]

Embedded image

In order for the urea structure to function as a color developer, it seems necessary to be enolized. The enolization requires high temperature conditions. Since the thermal head momentarily reaches a high temperature of 200 to 300 ° C, it is considered that the urea structure causes enolization and develops color by contact with the thermal head. Therefore, under temperature conditions below the temperature at which enolization occurs, the urea structure retains the keto type and does not develop color, so that the ground color is stable. This seems to be the reason why the ground color heat resistance is high.

On the other hand, the carboxyl group directly linked to the aryl group seems to have an acid-catalytic function for enolization of the urea structure, rather than being directly involved in the color developing property. The carboxyl group directly linked to the aryl group is considered to be useful, for example, in lowering the enolization temperature and improving the enolization rate (conversion ratio from keto type to enol type), and is therefore superior in terms of recording density. It is considered possible to obtain a thermosensitive recording medium.

Further, the ground color does not change by writing with the oil-based ink because the monourea compound of the present invention has a low solubility in the solvent used in the oil-based ink, and even if it is brought into contact with these solvents, it becomes a dye precursor. It is considered that this is because there is substantially no mixing with the developer.

[0056]

EXAMPLES <Synthesis of Monourea Compound> As a synthesis example of a monourea compound, synthesis examples of compounds A-1, A-2, A-3 and the like are shown below. Other monourea compounds were synthesized according to Synthesis Examples 1 to 16.

[Synthesis Example 1] Anthranilic acid (13.7 g, 100 m
M) was dissolved in acetone (200 ml). A solution prepared by dissolving phenyl isocyanate (13.1 g, 110 mM) in acetone (50 ml) was added dropwise to the reaction solution. After stirring at 60 ° C. for 1 hour, a white precipitate was produced. This precipitate was filtered and thoroughly washed with acetone and n-hexane until one spot was obtained on TLC to obtain compound A-1.

Synthesis Example 2 m-aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). A solution prepared by dissolving phenyl isocyanate (13.1 g, 110 mM) in acetone (50 ml) was added dropwise to this solution. Precipitation occurred after stirring at 50 ° C. for 1 hour. This is filtered, and TL is added with acetone and n-hexane.
Wash thoroughly until 1 spot on C
Got 2

[Synthesis Example 3] p-aminobenzoic acid (13.7 g, 100
mM) was dissolved in ethyl acetate (200 ml). To this solution, add phenyl isocyanate (13.1g, 110mM) to ethyl acetate (50ml).
The solution dissolved in was added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered, washed thoroughly with ethyl acetate and n-hexane until 1 spot was obtained on TLC,
Compound A-3 was obtained.

[Synthesis Example 4] 3-Aminotoluic acid (15.1 g, 1
00 mM) was dissolved in acetone (200 ml). A solution prepared by dissolving phenyl isocyanate (13.1 g, 110 mM) in acetone (50 ml) was added dropwise to this solution. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered, and acetone, n-hexane, T
Wash thoroughly until 1 spot on LC
I got A-5.

Synthesis Example 5 4-nitroanthranilic acid (18.
2 g, 100 mM) was dissolved in acetone (200 ml). Phenyl isocyanate (13.1 g, 110 mM) was added to this solution with acetone (5
A solution dissolved in 0 ml) was added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered and washed thoroughly with acetone and n-hexane until it became 1 spot on TLC,
Compound A-12 was obtained.

[Synthesis Example 6] 3-Amino-4-chlorobenzoic acid
(17.2 g, 100 mM) was dissolved in ethyl acetate (200 ml). A solution prepared by dissolving phenyl isocyanate (13.1 g, 110 mM) in ethyl acetate (50 ml) was added dropwise to this solution. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered, ethyl acetate, n-
The compound A-16 was sufficiently washed with hexane until 1 spot on TLC was obtained.

[Synthesis Example 7] p-aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). A solution of m-tolyl isocyanate (14.6 g, 110 mM) in acetone (100 ml) was added dropwise to this solution. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered, and acetone, n-hexane, T
Wash thoroughly until 1 spot on LC
I got A-19.

[Synthesis Example 8] p-aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). 4-Methoxyphenyl isocyanate (16.4 g, 110 mM) was added to this solution with acetone.
The solution dissolved in (100 ml) was added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered and sufficiently washed with acetone and n-hexane until one spot on TLC was obtained to obtain a compound A-27.

[Synthesis Example 9] p-aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). To this solution, m-trifluoromethylphenyl isocyanate (20.6 g, 110 mM)
Was dissolved in acetone (100 ml) and added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered, and with acetone and n-hexane until it became 1 spot on TLC,
After thorough washing, compound A-33 was obtained.

[Synthesis Example 10] p-Aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). To this solution was added p-chlorophenyl isocyanate (16.8g, 110mM) in acetone (1
(00 ml) was added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered and thoroughly washed with acetone and n-hexane until 1 spot on TLC was obtained to obtain a compound A-37.

Synthesis Example 11 p-aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). To this solution, a solution of benzyl isocyanate (14.6 g, 110 mM) in acetone (100 ml) was added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered, and acetone, n-hexane, T
Wash thoroughly until 1 spot on LC
I got A-39.

[Synthesis Example 12] p-Aminobenzoic acid (11.0 g, 80 m
M) was dissolved in acetone (400 ml). Add m-isopropenyl-α, α-dimethylbenzyl isocyanate to this solution.
A solution of (17.1 g, 85 mM) dissolved in acetone (50 ml) was added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered and sufficiently washed with acetone and n-hexane until it became one spot on TLC to obtain a compound A-41.

[Synthesis Example 13] p-Aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). A solution of ethyl isocyanate (7.8 g, 110 mM) in acetone (50 ml) was added dropwise to this solution. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered and thoroughly washed with acetone and n-hexane until 1 spot was obtained on TLC, to obtain compound A-47.

[Synthesis Example 14] p-aminobenzoic acid (13.7 g, 120
mM) was dissolved in acetone (400 ml). A solution of n-butyl isocyanate (10.9 g, 130 mM) dissolved in acetone (50 ml) was added dropwise to this solution. Precipitation occurred after stirring at 50 ° C. for 1 hour. This is filtered, and TL is added with acetone and n-hexane.
Wash thoroughly until 1 spot on C
Got 53.

Synthesis Example 15 p-aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). To this solution, tert-butyl isocyanate (10.9 g, 110 mM) was added acetone (50 ml).
The solution dissolved in was added dropwise. Precipitation occurred after stirring at 50 ° C. for 1 hour. This was filtered, acetone, n-hexane,
It was thoroughly washed until 1 spot was obtained on TLC to obtain compound A-57.

[Synthesis Example 16] m-aminobenzoic acid (13.7 g, 100
mM) was dissolved in acetone (400 ml). Cyclohexyl isocyanate (13.8 g, 110 mM) was added to this reaction solution with acetone (1
The solution dissolved in (00 ml) was added dropwise. A white precipitate was formed upon stirring at room temperature for 2 hours. This precipitate was filtered, and with acetone and n-hexane until it became 1 spot on TLC,
After thorough washing, compound A-58 was obtained.

<Production of Thermosensitive Recording Body> In the following description, parts and% mean parts by weight and% by weight, respectively. [Examples 1 to 28] As described below, a thermosensitive recording medium was produced using the urea compound of the present invention as a color developer and any of the following 6 types of dye precursors as a dye precursor. . (See Table 1 and Table 2) ODB: 3-diethylamino-6-methyl-7-anilinofluorane ODB-2: 3-dibutylamino-6-methyl-7-anilinofluorane TH-107: 3- Dibutylamino-7- (o-chloroanilino) fluorane CVL: 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide New Blue: 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-Ethyl-2-methylindol-3-yl) -4-
Azaphthalide Indolyl Red: 3,3-Bis (1-ethyl-2-methylindol-3-yl) phthalide That is, first, a developer dispersion (solution A) and a dye precursor dispersion (B) having the following composition The liquid) was ground with a sand grinder to an average particle size of 1 micron. (Liquid A: Developer dispersion liquid) Urea compound of the present invention 6.0 parts 10% polyvinyl alcohol aqueous solution 18.8 parts Water 11.2 parts (liquid B: dye precursor dispersion liquid) Each dye precursor 2.0 parts 10% polyvinyl alcohol aqueous solution 4.6 parts 2.6 parts of water Next, liquid A (developing agent dispersion liquid), liquid B (dye precursor dispersion liquid), and kaolin clay dispersion liquid were mixed at the following ratio to prepare a coating liquid. Solution A: Developer dispersion 36.0 parts Solution B: Dye precursor dispersion 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Coating solution 6.0 g / m ² on one side of 50 g / m ² base paper
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared.

[Comparative Examples 1 to 7] As described below, thermal recording materials for Comparative Examples were prepared in the same manner as in Examples 1 to 28 using the following compounds as the color developing agents. (See Table 2) (Developer compound) Bisphenol A (B-1) Bisphenol S (B-2) 4-hydroxy-4'-iso-propoxydiphenyl sulfone (B-3) 4-hydroxy-4'-n -Butyroxydiphenyl sulfone (B
-4) Phenylurea (B-5) JP-A-58-211496 JP Bisurea compound (B-6) JP-A-5-147357 JP Monourea compound (B-7) That is, The dispersion liquid of each developer compound shown in 1 was ground to an average particle size of 1 micron with a sand grinder. (C liquid: developer dispersion liquid) Developer compound (B-1 to B-7) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts Next, at the following ratio, liquid C (developing agent dispersion liquid) ), The dispersion liquid of the dye precursor used in Examples 1 to 18 (liquid B), and the dispersion liquid of kaolin clay were mixed to prepare a coating liquid. Liquid C: Developer dispersion 36.0 parts Liquid B: Dye precursor dispersion 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Coating solution 6.0g / on one side of 50g / m ² base paper
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared.

[0075]

[Chemical 15]

<Evaluation of Thermal Sensitive Recording Material> The thermal recording material thus obtained was subjected to a recording property test using a word processor, a thermal stability test for the background color, and an oil ink suitability test. [Recordability test (dynamic color density)]: A word processor (trade name: RUPO-90F / Co., Ltd.)
Using Toshiba's), the applied energy is maximum and recorded on the prepared thermal recording material, and the recording part is recorded by Macbeth densitometer (RD-9
14. An amber filter was used. Hereinafter, the concentration measurement was performed under these conditions. ). In this case, the larger the Macbeth value, the higher the recording density and the better the recording suitability. [Heat resistance test (static color density)]: In order to check the thermal stability of the ground color of the recording sheet, it was prepared at a pressure of 10 g / cm ² on a hot plate heated to 90 ° C, 120 ° C and 135 ° C, respectively. The heat-sensitive recording material was pressed for 5 seconds, and the recording material was measured with a Macbeth densitometer. In this case, the smaller the Macbeth value is, the less the ground color is colored and the higher the thermal stability of the ground color is. [Oil-based ink suitability test (ground color change test with oil-based ink)]: Oil-based red magic ink (Product name: Magic IN
K No.500 / manufactured by Teranishi Kagaku Co., Ltd. was used to write on the prepared thermosensitive recording medium, and the degree of discoloration to the original red color was visually measured. ◎ ... No discoloration ○ ... Almost no discoloration △ ... Slightly discolored × ... Remarkably discolored

Tables 1 and 2 show the evaluation results of Examples 1 to 28 in which the urea compound of the present invention was used as a developer and Comparative Examples 1 to 7 in which a known developer compound was used as a developer. It was shown to.

[0078]

[Table 1]

[Table 2]

[Embodiment 29] A heat-sensitive recording material of Embodiment 1 is sandwiched between pouch films, and a simple laminating apparatus (trade name: M
Thermal lamination was carried out using S Pouch H-140 / Meiko Shokai Co., Ltd. When the recorded part and the background color part were measured with a Macbeth densitometer, the recorded part was 1.40 and the background color part was 0.13.

[Embodiment 30] A heat-sensitive recording material of Embodiment 2 is sandwiched between pouch films, and a simple laminating apparatus (trade name: M
Thermal lamination was carried out using S Pouch H-140 / Meiko Shokai Co., Ltd. When the recorded part and the background color part were measured with a Macbeth densitometer, the recorded part was 1.35 and the background color part was 0.13.

[Embodiment 31] A heat-sensitive recording material of Embodiment 3 is sandwiched between pouch films and a simple laminating apparatus (trade name: M
Thermal lamination was carried out using S Pouch H-140 / Meiko Shokai Co., Ltd. When the recording part and the background color part were measured with a Macbeth densitometer, the recording part was 1.22 and the background color part was 0.12.

[Embodiment 32] In the thermal recording material of Embodiment 1, a copying machine (trade name: NP6060 / manufactured by Canon Inc.)
Then, when toner recording was performed, no change was observed in the background color, and printing could be performed.

[Embodiment 33] In the thermal recording material of Embodiment 2, a copying machine (trade name: NP6060 / manufactured by Canon Inc.)
Then, when toner recording was performed, no change was observed in the background color, and printing could be performed.

[Embodiment 34] In the thermal recording material of Embodiment 3, a copying machine (trade name: NP6060 / manufactured by Canon Inc.)
Then, when toner recording was performed, no change was observed in the background color, and printing could be performed.

[Embodiment 35] In the thermosensitive recording material of Embodiment 4, a copying machine (trade name: NP6060 / manufactured by Canon Inc.)
Then, when toner recording was performed, no change was observed in the background color, and printing could be performed.

<Production of Optical Recording Material> [Examples 36 to 40] As the dye precursor, 3-
Compound A-3 was prepared using N, N-diethylamino-6-methyl-7-anilinofluorane (alias: ODB) as a developer.
Then, an optical recording material was produced by using a heat-melted material of the following absorption dye and sensitizer as a light absorber. Cyanine dye (trade name: NK-2015 / manufactured by Japan Photosensitive Dye Research Institute) Naphthalocyanine dye (trade name: NIR-14 / Yamamoto Kasei Co., Ltd.) Immonium dye (trade name: IRG- 002 / Nippon Kayaku Co., Ltd.) Anthraquinone dye (trade name: IR-750 / Nippon Kayaku Co., Ltd.) Bisdithiobenzyl nickel complex (BDBNi). , 6 parts of the didithiobenzyl nickel complex were added, and 100 ~
The mixture was heated to 150 ° C., melt-mixed, and then pulverized to obtain a light absorber. Then, the light absorbent dispersion having the following composition was ground to an average particle size of 1 micron with a sand grinder. (Liquid D: Light Absorber Dispersion) Light Absorber 4.0 parts 10% Aqueous Polyvinyl Alcohol 10.0 parts Water 6.0 parts Then, at the following ratio, the compound A- used in Example 3
3 dispersion (Solution A), dye precursor (ODB) dispersion used in Examples 1-18 (Solution B), Solution D (light absorber dispersion), and Kaolin clay dispersion were mixed. To obtain a coating solution. Liquid A (developer dispersion liquid) 36.0 parts Liquid B (dye precursor dispersion liquid) 9.2 parts Liquid D (light absorber dispersion liquid) 20.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts This coating liquid 50 g / m Coating amount 6.0g / on one side of base paper ²
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared.

[Examples 41 to 42] As a light absorber, a heat-sensitive recording material was produced by using an absorbing dye alone instead of a thermal melt of each absorbing dye and a sensitizer. Toluenedithiol nickel complex (TDNi) 1,1,5,5-tetrakis (p-diethylaminophenyl) -3-
Methoxy-1,4-pentadiene (TDEPMP) The following light absorbing developer dispersion (solution H) was ground to an average particle size of 1 micron with a sand grinder. (Liquid H: Light Absorbing Developer Dispersion) Compound A-3 of Example 3 6.0 parts TDNi or TDEPMP 1.0 part 10% polyvinyl alcohol aqueous solution 18.8 parts water 10.2 parts Then, at the following ratio, Colorant dispersion (H
Liquid), the dispersion liquid of the dye precursor (ODB) used in Example 3 (liquid B), and the dispersion liquid of kaolin clay were mixed to prepare a coating liquid. Solution H (light-absorbing developer dispersion) 36.0 parts Solution B (dye precursor dispersion) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts This coating solution is applied to one side of 50 g / m ² base paper. Quantity 6.0g /
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared.

<Evaluation of Thermal Recording Material Containing Light Absorber>
A recording test was performed on the obtained thermal recording material. [Recordability test (optical recording)]: A laser plotter device described in JP-A-3-239598 was used to irradiate an optical recording medium with laser light, and the recording portion was measured with a Macbeth densitometer. As the light irradiation conditions, a semiconductor laser (product name: LT015MD / Sharp Co., Ltd.) with an oscillation wavelength of 830 nm and an output of 30 mW was used as a recording light source, and a light collecting lens with a numerical aperture of 0.45 and a focal length of 4.5 mm Using a spherical plastic lens (trade name: AP4545 / manufactured by Konica Corp.) at a recording speed of 50 mm / sec and a recording interval of 50 microns,
Solid prints of 1 cm in length and width were obtained. The evaluation results are shown in Table 3.

[0089]

[Table 3]

[0090]

As described above, the monourea compound of the present invention can be practically used by a thermal head or the like, even though the background color does not substantially change at the ambient temperature of 120 to 135 ° C. It is an epoch-making developer that can obtain sufficient image density recording. The effects of the present invention include, for example, the following points.

(1) The heat-sensitive recording material of the present invention is a heat-sensitive recording material having excellent background color stability such as heat resistance and solvent resistance as compared with the conventional heat-sensitive recording material. (2) The thermal recording medium of the present invention can be used under severe environmental conditions (for example, temperature conditions in the range of 90 ° C to 150 ° C). (3) The thermosensitive recording medium of the present invention can be freely written on the recording surface (the surface having the thermosensitive coloring layer) using an oil-based ink. (4) The thermosensitive recording medium of the present invention can be heat laminated with a plastic film by a simple laminating device or the like. Therefore, a card or the like can be easily made. (5) The heat-sensitive recording material of the present invention can be used for toner recording.

Similar effects can be expected even if the heat-sensitive recording material of the present invention contains a light absorbing agent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisami Satake 5-21-1 Oji, Kita-ku, Tokyo Inside Nippon Paper Industries Co., Ltd.

Claims (4)

[Claims] 1. A thermosensitive recording medium having a thermosensitive color developing layer comprising a colorless or light-colored dye precursor and a developer which reacts when heated to develop the color of the dye precursor, wherein the developer has the following general formula: The urea compound represented by (1), wherein the thermosensitive coloring layer contains at least one kind of the urea compound. Embedded image (Here, R is a phenyl group, an alkylphenyl group having 7 to 10 carbon atoms, an alkoxyphenyl group having 7 to 10 carbon atoms, a trihalogenated methylphenyl group, a halogenated phenyl group, and 7 to 10 carbon atoms. Aralkyl group of 10 to 12 carbon atoms
Represents an alkenylaralkyl group, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group, or a hydrogen atom. X
Is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a trihalogenated methyl group, a nitro group,
Represents a halogen atom or a hydrogen atom. ) 2. The thermosensitive recording medium according to claim 1, wherein the thermosensitive coloring layer contains a light absorbing agent which absorbs light and converts it into heat. 3. A heat-sensitive recording card in which the heat-sensitive recording material according to claim 1 or 2 is laminated with a plastic film. 4. A transfer sheet for electrophotography, which uses the thermosensitive recording medium according to claim 1 or 2.