JPH11321114A - Thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording medium having high image stability. SOLUTION: The thermal recording medium comprises a heat sensitive color developing layer containing a compound represented by a formula as a developer and at least one type of polyurea compound of 0.01 to 0.9 pt. to 1 pt. of the developer as a stabilizer (wherein R1 , R2 , R3 , and R4 are each, which may be the same or different, a hydrogen atom, 1-4C lower alkyl group or a halogen atom, R1 and R2 or R3 and R4 are bonded to one another which may form an aromatic ring, and X, Y are each, which may be the same or different, an oxygen atom or sulfur atom).

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 having excellent image stability, particularly, image stability against a plasticizer.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording medium generally comprises a colorless or pale-colored basic dye and a developer such as a phenol compound.
After grinding and dispersing each into fine particles, both are mixed,
Paints obtained by adding binders, fillers, sensitivity enhancers, lubricants and other auxiliaries, paper, synthetic paper, film,
This is a product coated on a support such as plastic, and a color is formed by an instantaneous chemical reaction caused by heating with a thermal head, a hot stamp, a hot pen, a laser beam or the like, thereby obtaining a recorded image. The thermal recording medium can be used in a wide range of applications such as facsimile machines, computer terminal printers, automatic ticket vending machines, measurement recorders, and has recently been used for various purposes such as home delivery slips and food barcode labels. However, in a conventional so-called dye-type thermosensitive recording medium in which a thermosensitive coloring layer containing a basic colorless dye, a color developer and a binder as active ingredients is coated on a support, a color image disappears with time. It was known and had been a problem. This decolorization is accelerated by exposure to light, high-temperature, high-humidity atmosphere, and further progresses significantly due to long standing in water, contact with oil such as salad oil, or plasticizer, and the image becomes unreadable. I will.

[0003] In order to suppress such a decoloring phenomenon, various techniques have been disclosed for heat-sensitive recording materials using a basic dye mainly composed of a colorless or pale-colored lactone ring compound. For example, Japanese Unexamined Patent Publication No.
As disclosed in JP-A-9-114096, a composition in which a phenolic antioxidant is incorporated in a thermosensitive coloring layer,
No. 46794, in which a hydrophobic polymer compound emulsion or the like is used for a protective layer.
As disclosed in Japanese Patent No. 4579, there is known a phenol-based developer in which an epoxy compound is used in combination. However, it is still insufficient for practical use, and a search for a new means for stabilizing an image is required.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to greatly improve the image stability of a thermosensitive recording medium, particularly, the image stability against a plasticizer.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a thermosensitive recording medium having the above-described performance, and as a result, the thermosensitive coloring layer contains a specific developer and a stabilizer. As a result, the inventors have found that the above object has been achieved, and have completed the present invention. That is, the present invention provides a thermosensitive recording medium provided with a thermosensitive coloring layer containing a colorless or pale-colored basic dye and an organic developer as main components, wherein the developer is at least one of the following general formula (1) Which is at least one kind of polyurea compound as a stabilizer in an amount of 0.01 to 0.9 part per 1 part of the developer.

[0006]

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In the formula, R ₁ , R ₂ , R ₃ and R ₄ may be the same or different and represent a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, or a halogen atom. Examples of the lower alkyl group having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and s.
ec-butyl group, or tert-butyl group,
Examples of the halogen atom include fluorine, chlorine, bromine, and iodine. Among them, a hydrogen atom or a methyl group is preferable, and among them, a hydrogen atom is particularly preferable. further,
R ₁ and R ₂ or R ₃ and R ₄ may be bonded to each other to form an aromatic ring. For example, a naphthalene ring may be combined with a benzene ring to which R ₁ and R ₂ or R ₃ and R ₄ are bonded. And the like. X and Y may be the same or different and represent an oxygen atom or a sulfur atom. That is,
When X is an oxygen atom and Y is also an oxygen atom, when X is an oxygen atom and Y is a sulfur atom, when is a sulfur atom and Y is an oxygen atom, when X is a sulfur atom and Y is also a sulfur atom Is mentioned.

[0008] When the compound represented by the general formula (1) is used as a color developer, image stability is extremely higher than when a conventional phenol-based color developer is used. The reason for this has not been clearly elucidated, but is presumed as follows. In general, a thermosensitive recording medium is constituted by using a basic colorless dye (dye precursor) as an electron donor and an organic acidic substance as an electron acceptor. Electrons are exchanged between these dye precursors and the developer by thermal melting, whereby a kind of charge transfer complex is formed and solidified to obtain a color-developed image. 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. The compound of the general formula (1) used as a color developer in the present invention has a plurality of so-called acidified nitrogen atoms having a reduced electron density adjacent to an electron-withdrawing group in the molecule. Due to this, the chemical bonding strength of acid and base is increased, and as a result, it is thought that the color is formed by the reaction between the developer and the basic colorless dye during the heat melting reaction and the recorded image is stabilized. . Therefore, even if the recorded image comes into contact with a plasticizer or the like, it is considered that the image is not easily erased.

In the present invention, the color developing ability of the polyurea compound used as a stabilizer itself is recognized, but is generally inferior to the color developing ability of an organic color developing agent used for a thermosensitive recording medium. However, by using the polyurea compound in a specific ratio to 1 part of the organic color developer, the compound functions as a stabilizer. The reason for this has not been clearly elucidated, but is presumed as follows. In the case of the present invention, it is presumed that when the developer and the dye react, the polyurea compound also thermally melts and one charge transfer complex is formed. It is considered that the solubility of the polyurea compound in the plasticizer is low, and thus, the formed charge transfer complex also has low solubility in the plasticizer. Therefore, by using the polyurea compound and the compound of the formula (1) together, a thermosensitive recording medium having high stability can be obtained.

The amount of the polyurea compound of the present invention contained in the heat-sensitive color-forming layer varies depending on the quality required. Insufficient effect, 0.9 parts per part of developer
If the number is larger than the required number, 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 0.9 parts.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The compound represented by the general formula (1) of the present invention can be synthesized by reacting 3-aminobenzenesulfonamide with an isocyanate compound or an isothiocyanate compound. For example, it can be easily obtained by reacting 3-aminobenzenesulfonamide represented by the formula (4) with an isocyanate compound represented by the general formula (5) or an isothiocyanate compound represented by the general formula (6).

[0012]

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R ₇ -NCO (5) wherein R ₇ is an unsubstituted monocyclic or condensed polycyclic aromatic ring (eg, benzene, naphthalene, etc.), a C ₁ -C ₄ alkyl group or a halogen atom Represents a monocyclic aromatic ring or a condensed polycyclic aromatic ring (to be referred to above) substituted with 2.

R ₈ -NCS (6) wherein R ₈ is an unsubstituted monocyclic or condensed polycyclic aromatic ring (see the above), a C ₁ -C ₄ alkyl group or halogen Represents a monocyclic aromatic ring or a condensed polycyclic aromatic ring (referred to above) substituted by 1 to 2).
The compound is reacted with an isocyanate compound or an isothiocyanate compound in an organic solvent or a water-containing solvent at a reaction temperature of 60 ° C. and under a neutral condition to produce a 3-sulfamoylcarbanilide compound. French Patent No. 99346 without isolation of the formed 3-sulfamoylcarbanilide compound
According to the method described in No. 5, an aqueous alkali hydroxide solution is added to form an alkali metal salt of a 3-sulfamoylcarbanilide compound, and then easily reacted with a corresponding isocyanate compound or isothiocyanate compound. Can be manufactured.

Examples of the isocyanate compound include phenyl isocyanate, toluene isocyanate, diisopropylphenyl isocyanate, chlorophenyl isocyanate, bromophenyl isocyanate, and naphthalene isocyanate. On the other hand, as the isothiocyanate compound, phenyl isothiocyanate, toluene isothiocyanate, chlorophenyl isothiocyanate, Bromophenyl isothiocyanate, naphthalene isothiocyanate and the like can be mentioned.

The organic solvent used in the reaction is acetone, methyl ethyl ketone, methyl isobutyl ketone, acetonitrile, dimethylformamide, dimethylsulfoxide, ethyl acetate, methanol, ethanol, preferably acetone, acetonitrile, dimethylformamide, dimethylsulfoxide. Examples of the alkali hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, and calcium hydroxide.

Specific examples of the compound represented by the general formula (1) used as a developer in the present invention include the following compounds, and these compounds may be used alone or in combination of two or more as necessary. These can be used together. 3-
(Phenylcarbamoylsulfamoyl) carbanilide, 3- (phenylcarbamoylsulfamoyl) thiocarbanilide, 3- (phenylthiocarbamoylsulfamoyl) carbanilide, 3- (phenylthiocarbamoylsulfamoyl) thiocarbanilide, 3- (p-tri Rucarbamoylsulfamoyl) carbanilide, 3-
(P-tolylcarbamoylsulfamoyl) thiocarbanilide, 3- (p-tolylthiocarbamoylsulfamoyl) carbanilide, 3- (p-tolylthiocarbamoylsulfamoyl) thiocarbanilide, 3- (m-tolylcarbamoylsulfamoyl) Carbanilide, 3-
(M-tolylcarbamoylsulfamoyl) thiocarbanilide, 3- (m-tolylthiocarbamoylsulfamoyl) carbanilide, 3- (m-tolylthiocarbamoylsulfamoyl) thiocarbanilide, 4-methyl-
3 ′-(phenylcarbamoylsulfamoyl) carbanilide, 3-methyl-3 ′-(phenylcarbamoylsulfamoyl) carbanilide, 4-methyl-3 ′-(phenylthiocarbamoylsulfamoyl) carbanilide, 3-methyl-3 '-(Phenylthiocarbamoylsulfamoyl) carbanilide, 4-methyl-3'-(phenylcarbamoylsulfamoyl) thiocarbanilide, 3-methyl-3 '-(phenylcarbamoylsulfamoyl) thiocarbanilide, 4-methyl-3' -(Phenylthiocarbamoylsulfamoyl) thiocarbanilide, 3-methyl-3 '-(phenylthiocarbamoylsulfamoyl) thiocarbanilide, 3- (p-chlorophenylcarbamoylsulfamoyl) carbanilide,
3- (m-chlorophenylcarbamoylsulfamoyl) carbanilide, 3- (p-chlorophenylthiocarbamoylsulfamoyl) carbanilide, 3- (m-chlorophenylcarbamoylsulfamoyl) thiocarbanilide, 4-chloro-3 ′-(phenylcarbamoyl) Sulfamoyl) carbanilide, 3-chloro-3 ′-(phenylcarbamoylsulfamoyl) carbanilide, 4
-Bromo-3 '-(phenylcarbamoylsulfamoyl) carbanilide, 4-chloro-3'-(p-chlorophenylcarbamoylsulfamoyl) carbanilide, 4
-Chloro-3 '-(phenylcarbamoylsulfamoyl) thiocarbanilide, 4-chloro-3'-(phenylthiocarbamoylsulfamoyl) thiocarbanilide,
3- (α-naphthylcarbamoylsulfamoyl) carbanilide, 3- (β-naphthylcarbamoylsulfamoyl) carbanilide, 1- (α-naphthyl) -3- (m
-Phenylcarbamoylsulfamoylphenyl) urea, 3- (α-naphthylthiocarbamoylsulfamoyl) carbanilide, 3- (β-naphthylthiocarbamoylsulfamoyl) carbanilide, 1- (α-naphthyl) -3- (m -Phenylcarbamoylsulfamoylphenyl) thiourea, 1- (β-naphthyl) -3- (m
-Phenylcarbamoylsulfamoylphenyl) thiourea, 1- (α-naphthyl) -3- (m-α-naphthylcarbamoylsulfamoylphenyl) urea, 1- (α
-Naphthyl) -3- (m-α-naphthylcarbamoylsulfamoylphenyl) thiourea. Especially 3
-(Phenylthiocarbamoylsulfamoyl) carbanilide is preferable because it has good plasticizer resistance.

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 (RDKatsaravaetal., M
Chem., 194, 3209 (1993)), and (i) a method of synthesizing from diisocyanate and benzoic acid in dimethyl sulfoxide (WRSorensen, J. Org. Chem., 24, 978 (1959)). 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 present invention, the polyurea compound represented by the general formula (2) or (3) is effectively used.
In the general formula (2) or (3), 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 (7) and (8), but the present invention is not limited to these.

[0021]

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[0022]

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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.

[0024]

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[0025]

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[0026]

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[0027]

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A general method for producing the heat-sensitive recording material of the present invention is to disperse a colorless or pale-colored basic dye, a color developer, and at least one polyurea as a stabilizer together with a binder, if necessary. In this method, a coating liquid is prepared by adding an auxiliary agent such as a filler, a lubricant, an ultraviolet absorber, a water-proofing agent, an antifoaming agent, and the like, and is applied and dried on a support by a usual method. As the colorless or light-colored basic dye used in the heat-sensitive recording medium of the present invention, any known dyes in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and there is no particular limitation. Preference is given to methane compounds, fluoran compounds, fluorene compounds, divinyl compounds and the like. Specific examples of typical colorless or pale color dyes (dye precursors) are shown below. These dye precursors may be used alone or
You may mix and use more than one kind.

Triphenylmethane leuco dye 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] 3,3-bis (p-dimethylaminophenyl) phthalide [also known as 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-m-methylanilinofluoran 3-diethylamino-6-methyl-7-n-octylanilino Fluoran 3-diethylamino-6-methyl-7-n-octylaminofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl-7-dibenzylanilinofluoran 3- Diethylamino-6-chloro-7-methylfluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-chloro-7-p-methylanilinofluoran 3-diethylamino-6-ethoxyethyl -7-anilinofluoran 3-diethylamino-7-methylfluoran 3-diethylamino-7-chlorofluorane 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-7- (o- Chloroanilino) fluoran 3-diethylamino-7 (P-chloroanilino) fluoran 3-diethylamino-7- (o-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) Fluorane 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 Le-chlorofluorane 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran 3-dibutylamino-6-chloro-7-anilinofluoran 3-dibutylamino-6-methyl-7-p-methyl Anilinofluoran 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-7- (m-trifluoromethylanilino) fluoran 3-n-dipentylamino-6-chloro-7- Anilinofluoran 3-n-dipentylamino-7- (p-chloroanilino) fluoran 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, conventionally known color developers can be used in combination according to the desired image stability and recording sensitivity within a range that does not impair the desired effects on the above-mentioned problems.
However, the addition amount is desirably small, and is about 0.01 to 0.9 part per 1 part of the compound of the general formula (1). When manufacturing a thermosensitive recording medium having extremely excellent image storability, it is better not to use the thermosensitive recording medium together.

In the present invention, conventionally known sensitizers can be used as long as the desired effects on the above objects are not impaired. Examples of such a sensitizer include fatty acid amides such as stearic acid amide and palmitic acid amide, methylolated fatty acid amides such as ethylenebisamide and methylol stearic acid amide, montanic acid wax, polyethylene wax, 1,2-di- (3-methyl Phenoxy)
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-
Examples thereof include bis- (phenyl ether) and 4- (m-methylphenoxymethyl) biphenyl, but are not particularly limited thereto. 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, It is also possible to add a metal salt of monobenzyl phthalate (Ca, Zn) or a diphenylsulfone derivative. Fillers that can be used in the present invention include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide,
Examples include inorganic or organic fillers such as zinc oxide, aluminum hydroxide, polystyrene resin, urea-formalin resin, styrene-methacrylic acid copolymer, styrene-butadiene copolymer, and hollow plastic pigment. In addition, release agents such as fatty acid metal salts, lubricants such as waxes, benzophenone-based and triazole-based ultraviolet 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. Further, an overcoat layer of a polymer substance or the like can be provided on the thermosensitive coloring layer for the purpose of enhancing the storage stability.
Further, for the purpose of improving the storage stability and sensitivity, an undercoat layer containing an organic filler or an inorganic filler can be provided between the color-forming layer and the support.

The amounts of the developer and the basic colorless dye used in the heat-sensitive recording medium of the present invention, and the types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited. Is usually used as a dye with respect to 1 part of the compound represented by the general formula (1) used as a developer.
1 to 2 parts and 0.5 to 4 parts of filler are used, and the binder is suitably 5 to 25% of the total solid content. The polyurea compound of the present invention is used in an amount of 0.01 to 0.9 parts per part of the developer.

These developers, dyes and materials to be added as required are pulverized by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifier to a particle size of several microns or less. 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.

[0041]

EXAMPLES Synthesis of Compound of General Formula (1) Synthesis Example 1 Synthesis of 3- (phenylcarbamoylsulfamoyl) carbanilide 3-Aminobenzenesulfone was placed in a 500 ml four-necked flask equipped with a stirrer, a condenser and a thermometer. 17.2 g of amide,
Acetonitrile (200 ml) was charged and dissolved by stirring. Next, while maintaining the solution temperature at 20 ° C., acetonitrile 50
11.9 g of phenyl isocyanate dissolved in 1 ml
Dropped in time. Thereafter, the reaction was carried out for 6 hours to produce 3-sulfamoylcarbanilide. The generated 3-sulfamoylcarbanilide was added to the reaction mixture without isolation.
After adding 42 g of a 0% aqueous sodium hydroxide solution and stirring for 1 hour, 11.9 g of phenyl isocyanate dissolved in 50 ml of acetonitrile was added dropwise over 1 hour, and the reaction was carried out for 6 hours. After completion of the reaction, acetonitrile was distilled off under reduced pressure, and 200 g of water and 100 ml of ethyl acetate were added to the concentrated residue to extract an unreacted substance, and the aqueous layer was separated. When the aqueous solution was acidified with hydrochloric acid, white crystals were precipitated. The crystals were collected by filtration and recrystallized from ethyl acetate to give 34 g of white crystals having a melting point of 197 to 199 ° C.
Obtained. It was confirmed from infrared spectroscopy, mass spectrometry and elemental analysis that the white crystals were 3- (phenylcarbamoylsulfamoyl) carbanilide.

Synthesis Example 2 Synthesis of 3- (phenylcarbamoylsulfamoyl) thiocarbanilide In the reaction between 3-aminobenzenesulfonamide and phenylisocyanate of Synthesis Example 1, except that 13.5 g of phenylisothiocyanate was used instead of phenylisocyanate. The same operation as in Synthesis Example 1 was carried out to give a melting point of 170 to 17.
25 g of 2 ° C. white crystals were obtained. From infrared spectroscopy, mass spectrometry and elemental analysis, it was confirmed that the white crystal was 3- (phenylcarbamoylsulfamoyl) thiocarbanilide.

Synthesis Example 3 Synthesis of 3- (phenylthiocarbamoylsulfamoyl) carbanilide The same reaction as in Synthesis Example 1 was performed to produce 3-sulfamoylcarbanilide, and phenylisothiocyanate 13 was used instead of phenylisocyanate. The same operation as in Synthesis Example 1 was performed except that 0.5 g was used, to obtain 25 g of white crystals having a melting point of 165 to 168 ° C. From infrared spectroscopy, mass spectrometry and elemental analysis, it was confirmed that the white crystal was 3- (phenylthiocarbamoylsulfamoyl) carbanilide.

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 <Spinning property> Available <Viscosity> 20 .3mPa · s

Synthesis Example 3 Synthesis of polyurea compound (a06) using 2,4-TDI and 4,4′-diaminodiphenylmethane 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> 20.1 mPa · s

Synthesis Example 4 Synthesis of polyurea compound (a15) using 2,4-TDI and 1,6-hexamethylenediamine 2.67 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 Synthesis of polyurea compound (a21) using 2,6-TDI and 1,6-hexamethylenediamine 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 Hereinafter, the thermosensitive recording material of the present invention will be described with reference to Examples.
In the description, parts and% represent parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 In Example 1, the heat-sensitive recording medium of the present invention was prepared by adding 3-
(Phenylcarbamoylsulfamoyl) carbanilide (hereinafter abbreviated as compound (I)), 3-dibutylamino-6-methyl-7-anilinofluoran (ODB-2) as a basic colorless dye, Urea (a0
This is an example using 3). A developer dispersion (solution A), a basic colorless dye dispersion (solution B), and a sensitizer dispersion (solution C) having the following composition are separately separated by a sand grinder until the average particle diameter becomes 1 micron. Wet grinding was performed. Liquid A (developer dispersion liquid) Compound (I) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Liquid B (dye dispersion liquid) 3-dibutylamino-6-methyl-7-aniline Linofluorane (ODB-2) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts Liquid C (stabilizer dispersion) Polyurea (a03) 2.0 parts 10% aqueous polyvinyl alcohol solution 18 8 parts water 11.2 parts Next, the dispersion liquid was mixed and stirred at the following ratio to prepare a coating liquid. Solution A (Developer [Compound (I)] dispersion) 36.0 parts Solution B (Dye [ODB-2] dispersion) 9.2 parts Solution C (Stabilizer [Polyurea (a03)] dispersion) 32.0 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above coating solutions was applied to one surface of a base paper of 50 g / m ² , dried, and the sheet was supercalendered. And a coating amount of 6.0 g / m ² was obtained.

Examples 2 to 4 Thermal recording paper was prepared in the same manner as in Example 1. Where A
In preparing the solution, 3- (phenylcarbamoylsulfamoyl) carbanilide (compound (I)) was replaced with 3
-(Phenylcarbamoylsulfamoyl) thiocarbanilide (compound (II)), 3- (phenylthiocarbamoylsulfamoyl) carbanilide (compound (III))
And 3- (phenylthiocarbamoylsulfamoyl)
Thiocarbanilide (compound (IV)) was used.

Example 5 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, two types of developers, 3- (phenylcarbamoylsulfamoyl) thiocarbanilide (compound (II)) and 3- (phenylthiocarbamoylsulfamoyl) carbanilide (compound (III)), were used. In addition, each dispersion liquid was mixed and stirred as described below to prepare a coating liquid. Liquid A (developer [compound (II)] dispersion) 18.0 parts Liquid A (developer [compound (III)] dispersion] 18.0 parts Liquid B (dye [ODB-2] dispersion) 9.2 parts C liquid (stabilizer [polyurea (a03)] dispersion) 32.0 parts Kaolin clay (50% dispersion) 12.0 parts

Examples 6 to 8 Thermal recording papers were prepared in the same manner as in Example 2. However, B
In preparing the solution, 3-dibutylamino-6-methyl-7
-Instead of anilinofluoran (ODB-2), 3-diethylamino-6-methyl-7-anilinofluoran (ODB; Example 6), 3- (N-ethyl-N-isoamylamino) -6 Methyl-7-anilinofluoran (S-205; Example 7), 3-diethylamino-7-
(M-trifluoromethylanilino) fluoran (Bl
ack100; Example 8) was used.

Example 9 A thermosensitive recording paper was prepared in the same manner as in Example 2. However, 3- (N-ethyl-N-isoamylamino) is used as the dye.
-6-methyl-7-anilinofluoran (S-205)
And 3-dibutylamino-6-methyl-7-anilinofluoran (ODB-2). In addition, each dispersion liquid was mixed and stirred as described below to prepare a coating liquid. Solution A (Developer [Compound (II)] dispersion) 36.0 parts Solution B (Dye [S-205] dispersion) 4.6 parts Solution B (Dye [ODB-2] dispersion) 4.6 Part C liquid (stabilizer [polyurea (a03)] dispersion) 32.0 parts kaolin clay (50% dispersion) 12.0 parts

Examples 10 to 13 Thermal recording papers were prepared in the same manner as in Example 2. Where C
In preparing the liquid, polyurea (a01), (a06), (a15) and (a21) were used instead of polyurea (a03).
Was used.

Example 14 A thermosensitive recording paper was produced in the same manner as in Example 1. Where C
In preparing the solution, two types of polyureas (a03) and (a05) were used. In addition, each dispersion liquid was mixed and stirred as described below to prepare a coating liquid. Solution A (Developer [Compound (II)] dispersion) 36.0 parts Solution B (Dye [ODB-2] dispersion) 9.2 parts Solution C (Stabilizer [Polyurea (a03)] dispersion) 16.0 parts liquid C (stabilizer [polyurea (a05)] dispersion) 16.0 parts kaolin clay (50% dispersion) 12.0 parts

Comparative Example 1 A thermosensitive recording paper was prepared in the same manner as in Example 9. However, the liquid C was not mixed in the formation of the coloring layer. Comparative Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 9. Where A
In preparing the solution, instead of compound (II), 4,4′-
Isopropylidene diphenol (bisphenol A; abbreviated as BPA in the table) was used.

Comparative Example 3 A thermosensitive recording paper was prepared in the same manner as in Example 9. However, the liquid C was adjusted as described below in the formation of the coloring layer. C 'liquid (stabilizer dispersion liquid) Polyurea (a03) 0.030 parts 10% aqueous polyvinyl alcohol solution 0.282 parts Water 0.168 parts Next, the dispersion liquid was mixed and stirred at the following ratio to prepare a coating liquid. . Solution A (Developer [Compound (II)] dispersion) 36.0 parts Solution B (Dye [S-205] dispersion) 4.6 parts Solution B (Dye [ODB-2] dispersion) 4.6 Part C liquid (stabilizer [polyurea (a03)] dispersion) 0.48 part kaolin clay (50% dispersion) 12.0 parts

Comparative Example 4 A thermosensitive recording paper was prepared in the same manner as in Example 9. However, the liquid C was adjusted as described below in the formation of the coloring layer. C〃 Solution (Stabilizer dispersion) 9.0 parts of polyurea (a03) 10% aqueous solution of polyvinyl alcohol 84.6 parts Water 50.4 parts Next, the dispersion was mixed and stirred at the following ratio to prepare a coating liquid. . Solution A (Developer [Compound (II)] dispersion) 36.0 parts Solution B (Dye [S-205] dispersion) 4.6 parts Solution B (Dye [ODB-2] dispersion) 4.6 Part C liquid (stabilizer [polyurea (a03)] dispersion) 144.0 parts kaolin clay (50% dispersion) 12.0 parts

Evaluation of heat-sensitive recording medium The prepared heat-sensitive recording medium was measured using a TH-P manufactured by Okura Electric Co., Ltd.
Using an MD (thermal recording paper printing tester, manufactured by Kyocera, with a thermal head attached), applied energy -0.41 mj / d
Printed at ot. The image recording density of the recorded sample was measured using a Macbeth densitometer (RD-914, Amber filter).
Used) to obtain the untreated concentration. The ground color density was measured in the same manner. Then, a vinyl wrap (Mitsui Toatsu High Wrap KMA) is wrapped around the paper tube in a single layer, and the thermosensitive recording medium recorded thereon is pasted thereon. After standing for 24 hours, the Macbeth density in the image area was measured. (See Tables 1 and 2)

[0061]

[Table 1]

Note) Content ratio to 1 part of developer * 1: 0.005 * 2: 1.5

[0063]

[Table 2]

As is evident from the results of Tables 1 and 2, Examples 1 to 14 of the present invention using the compound represented by the general formula (1) and the polyurea compound showed a comparison between only one of them. Compared with Examples 1 and 2, the image stability to the plasticizer is significantly higher. Therefore, it can be seen that the compound represented by the general formula (1) and the polyurea each have a low resistance to a plasticizer when used alone, and show an excellent stabilizing effect only when used in combination. Further, the polyurea was contained in a proportion of 0.005 part in Comparative Example 3 and 1.5 parts in Comparative Example 4 with respect to 1 part of the compound represented by the general formula (1). The recording density was low when the polyurea content was too large (Comparative Example 4). That is, even when the compound represented by the general formula (1) and the polyurea are present at the same time, the polyurea defined in the present invention is not converted into the general formula (1)
It can be understood that the desired stability cannot be obtained unless the condition of containing 0.01 to 0.9 part with respect to 1 part of the compound represented by is satisfied.

[0065]

The heat-sensitive recording material of the present invention has sufficient color development sensitivity and extremely excellent image stability, especially stability against a plasticizer. Therefore, even if it comes into contact with a plasticizer contained in a wrap film, a leather product, or the like, the recorded image is not erased, so that it is highly practical. Further, since the heat-sensitive recording medium of the present invention contains the compound represented by the general formula (1) and polyurea in the color-forming layer, the heat-sensitive recording medium has a plasticizer resistance without requiring a protective layer. It can be applied, and is excellent in economic efficiency.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naomi Sumikawa 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Inside Japan Product Research Laboratory (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 having thereon a heat-sensitive coloring layer containing a colorless or pale-colored basic dye and an organic color developing agent as main components, wherein at least one color developing agent is used.
A compound represented by the following general formula (1), wherein at least one polyurea compound is contained as a stabilizer in an amount of 0.01 to 0.9 part relative to 1 part of the developer. Characterized thermal recording medium. Embedded image (Wherein, R ₁ , R ₂ , R ₃ , and R ₄ may be the same or different and represent a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms, or a halogen atom, and R ₁ and R ₂ or R ₃ and R ₄ may combine with each other to form an aromatic ring, and X and Y may be the same or different and each represent an oxygen atom or a sulfur atom.) 2. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive coloring layer contains a polyurea compound having a repeating unit represented by the following general formula (2). Embedded image (In the formula, A ¹ represents a divalent group.) 3. The thermosensitive recording medium according to claim 1, wherein the thermosensitive coloring layer contains a polyurea compound having a repeating unit represented by the following general formula (3). Embedded image (In the formula, one of R ⁵ and R ⁶ represents a hydrogen atom and the other represents a methyl group. A ² represents a divalent group.)