JP3336596B2 - Thermal recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium having excellent ground color stability and a thermosensitive recording medium having vivid color tone reversible recording properties.

[0002]

2. Description of the Related Art In general, a thermosensitive recording medium is usually a colorless or pale-colored electron-donating colorless dye and a developer such as a phenolic compound, each of which is ground and dispersed into fine particles, and then mixed. A coating solution obtained by adding a binder, filler, sensitivity enhancer, lubricant, and other auxiliaries is applied to a support such as paper, synthetic paper, film, plastic, etc. The color is developed by an instantaneous chemical reaction caused by heating with light or the like to obtain a visible record.

[0003] Thermal recording media have been applied to a wide range of fields, such as measurement recorders, computer terminal printers, facsimile machines, automatic ticket vending machines, and bar code labels. However, recently, diversification of recording devices for thermal recording media,
As the performance has been improved, the quality required for the thermosensitive recording medium has become higher. For example, from the viewpoint of high-speed recording, it is possible to obtain a high-density and clear color image even with a smaller amount of thermal energy. On the other hand, from the viewpoint of the storage stability of the recording medium, light resistance,
It is required to have excellent oil resistance, water resistance and solvent resistance.

[0004] On the other hand, as systems for recording on plain paper such as the electrophotographic system and the ink jet system have become widespread, there are increasing opportunities for comparing thermal recording with plain paper recording. For example, it is required that the stability of a recording portion (image) and the stability of a non-recording portion (ground color portion) before and after recording (hereinafter referred to as ground color stability) approach the quality of plain paper recording. ing. In particular, as a basic function of thermal recording, ground color stability to heat and a solvent has been required, and so to speak, it is desired that the recording medium is heat-sensitive only at the time of recording, and otherwise it is insensitive to heat.

Regarding the ground color stability of a thermal recording medium, for example,
Japanese Patent Application Laid-Open No. 4-353490 discloses a thermosensitive recording medium in which the whiteness of the ground color and the recording density do not decrease even under a high temperature condition of about 90 ° C.

[0006] On the other hand, the rapid increase in the consumption of recording media accompanying the spread of various networks, facsimile machines, and copiers has caused social problems such as garbage disposal. As one idea for addressing this problem, a reversible recording medium capable of recording and erasing repeatedly has attracted attention.

[0007] Reversible recording media are described in detail in review articles such as JPA 47 11 (1993) p1309-1322. For example, JP-A-3-230993, JP-A-4-366682, etc. In addition, a recording medium utilizing the reversible change of the recording material to a transparent state and a cloudy state by a given temperature is disclosed, and in addition, a recording medium utilizing the reversibility of a thermochromic material, a reversible leuco dye A recording medium using a great change in color tone has been proposed.

[0008]

The ground color stability of the heat-sensitive recording medium disclosed in Japanese Patent Application Laid-Open No. 4-353490 is 95%
When treated at 5 ° C. for 5 hours, the Macbeth density of the ground color is about 0.11, showing considerable stability, but still insufficient, and it is not possible to apply thermal lamination to the colored surface with a plastic film. Was.

Regarding a reversible recording medium, a recording medium utilizing a reversible change of the recording material between a transparent state and a cloudy state (in other words, a recording medium utilizing a change in the transparency of the recording material) is used. (1) Lack of image clarity,
(2) There are drawbacks such as a low whitening (decoloring) rate, and (3) a temperature control is required for erasing. In addition, in this record, in order to give a contrast between cloudiness and transparency,
There is no problem in using it as a transparent recording medium such as OHP, but for example, when a recording material is applied to a white opaque support like a conventional thermal recording medium, it is necessary to provide a colored layer on the back. is there. Therefore, the coating layer on the colored layer (the layer that reversibly changes to a transparent / opaque state) also needs a thin layer in order to give a contrast, in other words, to clearly show the color of the colored layer (the color of the base). On the other hand, on the other hand, to make it look white, a thick layer is preferable, and strictness of the coating layer is necessary.

In a reversible recording medium using a thermochromic material, most of the thermochromic material is
There are problems such as poor memory performance and the necessity of continuous heat supply to maintain a colored state.

On the other hand, a reversible recording medium using a leuco dye as a coloring source is disclosed in JP-A-60-193691 and JP-A-60-196369.
Japanese Patent No. 257289 discloses a reversible recording medium. However, these recording mediums perform erasing with water or water vapor, and have a problem in practical use. In addition, JP-A No. 2-18
No. 8293, JP-A-2-188294, and the like, a material having a simple layer structure and having both a developing color and a color-reducing effect of giving a reversible color tone change to a leuco dye only by controlling thermal energy (a color-reducing agent) ) Is disclosed. However, with this developer, the color erasing process has already contributed during the color developing process, so that there was a problem that the color density was low. Also recently, Ja
In Pan Hardcopy '93, Yokota et al. published a record using an amide phenol derivative having a long-chain alkyl, but this record also requires temperature control for erasure. There were drawbacks.

Accordingly, it is an object of the present invention to provide a thermosensitive recording medium having excellent ground color stability against heat and a solvent as a basic function. Also, as an additional function,
It is an object of the present invention to provide a thermosensitive recording medium having reversible recording properties capable of erasing and re-recording.

[0013]

The above object has been achieved by a thermosensitive recording medium using a naphthyl urea-based developer having a structure completely different from that of a general phenol-based developer.

According to the present invention, there is provided a thermosensitive recording medium having a thermosensitive coloring layer containing a colorless or pale color dye precursor and a developer which reacts upon heating to form the dye precursor. The present invention relates to a urea compound represented by the general formula (1), (2) or (3), wherein the thermosensitive coloring layer contains at least one kind of the urea compound.

[0015]

Embedded image (Where X represents an alkyl group having 1 to 6 carbon atoms, a halogen atom, or a hydrogen atom. Y represents a divalent group having up to 30 carbon atoms, and Z represents a divalent group having up to 30 carbon atoms. Represents a trivalent group composed of 30 or less.)

The urea compound represented by the general formula (1), (2) or (3) has a naphthyl urea structure (R-NH-C = O
-NH-, R = -Naphtyl). The urea compound of the general formula (1) is a compound in which two naphthyl urea structures are directly connected, and the urea compound represented by the general formula (2) or (3) is a compound of two to three naphthyl ureas. The structure is a compound linked by a joint group. The joint group is a divalent or trivalent group having 30 or less carbon atoms.

The urea compound represented by the general formula (1) or (2) (referred to as a dimerized urea compound in the present invention) and the urea compound represented by the general formula (3) (in the present invention, (It is called a trimerized urea compound.)
Can be synthesized by, for example, a reaction of an amine with an isocyanate compound.

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First, the dimerized urea compound represented by the general formula (2) is prepared by reacting (a) a diamine with a monoisocyanate compound or (b) a diisocyanate compound with a monoamine. It is possible to synthesize by such as.

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When a diisocyanate is reacted with a monoisocyanate compound, the diamines include carbohydrazide, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-diaminobutane, and 1,3-diamino. Pentane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,
9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-diamino-2-methylpropane, 1,3-diamino-2,2-dimethylpropane, 1 , 5-Diamino-2-methylpentane, 1,5-diamino-2,2-dimethylpentane, trimethylhexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 3,3'-diaminodipropylamine, N , N-bis (3-aminopropyl) methylamine, bis (3-aminopropyl) ether, 1,8-diamino-3,6-dioxaoctane, ethyleneglycolbis (3-aminopropyl) ether Ter, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-di (aminomethyl) cyclohexane, 1,4-di (aminomethyl) cyclohexane, 4,4'- Diamino Phenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodicyclohexyl Methane, 4,4 '
-Diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dichlorodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-diamino-1 , 2-Diphenylethane, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diaminodiphenylamine, 2,2'-diaminodiphenyldisulfide, 4,4'-diaminodiphenyldisulfide, 1,3 -Bis (m-aminophenoxy) benzene, 1,4-bis (m-aminophenoxy) benzene, 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis [4- (4-aminophenoxy) ) Phenyl] hexafluoropropane, α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene,
3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,4-diaminoazobenzene, 4,4'-diaminostilbene, 4,4'-diaminostilbene-2,2'-disulfonic acid, o-phenylene Diamine, m-phenylenediamine,
p-phenylenediamine, 4-chloro-o-phenylenediamine, 5-chloro-m-phenylenediamine, 2-chloro-p-phenylenediamine, 2-nitro-1,4-phenylenediamine, 4-nitro-1,2 -Phenylenediamine, 4-nitro-1,3
-Phenylenediamine, 2,4-diaminoanisole, p, p '
-Methylene dianiline, m-xylylenediamine, p-xylylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,4-diaminobenzoic acid, 3,5-diaminobenzoic acid, 1,5 -Diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene, 1,2-diaminoanthraquinone, 1,4-diaminoanthraquinone, 1,5-diaminoanthraquinone, 2,6-diaminoanthraquinone, 1,4- Diamino-2,3-dicyano-9,10-anthraquinone, 2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diamino-6-chloropyrimidine, 2,4- Diamino
-6-phenyl-1,3,5-triazine, 9,9-bis (4-aminophenyl) fluorene, piperazine, N-aminoethylpiperazine, 1,4-bis (3-aminopropyl) piperazine,
Examples include isophorone diamine, and examples of the monoisocyanate compound include naphthyl-based isocyanate compounds such as 1-naphthyl isocyanate and 2-naphthyl isocyanate, and any combination thereof can be selected.

On the other hand, when a monoamine is reacted with a diisocyanate compound, the diisocyanate compound may be 2,4-toluene diisocyanate (2,4-TDI) or 2,6-toluene diisocyanate. -(2,6-TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalenediisocyanate (NDI), tolidine diisocyanate (TODI)
Hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), p-phenylene diisocyanate, m-phenylene diisocyanate, transcyclohexane 1,4-diisocyanate, Xylylene diisocyanate (XDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), lysine diisocyanate (LDI)
, M-tetramethylxylene diisocyanate (m-TMXDI)
, P-tetramethylxylene diisocyanate (p-TMXDI)
And the like, as monoamines, 1-naphthylamine, 2-
Examples include naphthylamines such as naphthylamine, 2-methyl-1-naphthylamine, and 2-chloro-1-naphthylamine, and any combination thereof can be selected.

In the case of the dimerized urea compound represented by the general formula (1), hydrazine is used as a diamine, and the aforementioned compound is used as a monoisocyanate compound.
Just combine them.

On the other hand, the trimerized urea compound represented by the general formula (3) can be synthesized by a method of reacting a triamine with a monoisocyanate compound or a method of reacting a triisocyanate compound with a monoamine. Is possible.

First, when a monoisocyanate compound is reacted with a triamine, 1,2,4-
Examples of the monoisocyanate compound include triaminobenzene, tris (2-aminoethyl) amine, melamine, 2,4,6-triaminopyrimidine, triamterene, etc., and the above-mentioned compounds can be used. be able to. On the other hand, when a monoamine is reacted with a triisocyanate compound, triphenylmethane triisocyanate, tris (isocyanate-phenyl) thiophosphate, lysine ester triisocyanate, , 6,11-Undecane triisocyanate, 1,8-diisocyanate-4
-Isocyanate methyl octane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate and the like, and monoamines include the above-mentioned compounds, and any combination of both. You can choose.

The following compounds can be exemplified as specific examples of the urea compound represented by the general formula (1), (2) or (3).

[0025]

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The joint group should be appropriately selected depending on the melting point, decomposition temperature, solubility in a solvent and the like of the urea compound, and is not particularly limited. For example, when the joint group (Y) of the urea compound of the general formula (2) is roughly classified, the following can be mentioned.

(1) A linear alkylene group having 1 to 12 carbon atoms.

(2) An alkylene group having 1 to 15 carbon atoms and having a branched chain.

(3) A plurality of alkylene groups having 1 to 12 carbon atoms and linked by a nitrogen atom or an oxygen atom. Here, examples of the plurality of alkylene groups linked by a nitrogen atom or an oxygen atom include the following structures. (When linked by a nitrogen atom)

Embedded image (Where L1 = 1 to 11 and M1 = 1 to 11 are integers, and L1 + M1 = 2
~ 12. )

Embedded image (Where L2 = 1-10, M2 = 1-10, N2 = 1-10, and L2
+ M2 + N2 = 3 to 12. )

Embedded image (Here, L3 = 1-9, M3 = 1-9, N3 = 1-9, Q3 = 1-9, and L3 + M3 + N3 + Q3 = 4-12.)

Embedded image (Here, L4 = 1 to 8, M4 = 1 to 2, N4 = 1 to 8 are integers, and L4 + 3 × M4 + N4 = 5 to 12.)

Embedded image (Here, L5 = 1 to 7, M5 = 1 to 2, N5 = 1 to 7 are integers, and L4 + 4 × M4 + N4 = 6 to 12.) (When linked by an oxygen atom)

Embedded image (Where L6 = 1-11, M6 = 1-11, L6 + M6 = 2-12
It is. )

Embedded image (Where L7 = 1-10, M7 = 1-10, N7 = 1-10, L7
+ M7 + N7 = 3 to 12. )

Embedded image (Here, L8 = 1-9, M8 = 1-9, N8 = 1-9, R8 = 1-9, and L8 + M8 + N8 + Q8 = 4-12.) A nitrogen atom When the hydrogen atom bonded to the nitrogen atom of the joint group is substituted with an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 18 carbon atoms, It may be replaced.

(4) A group having 1 to 20 carbon atoms and containing at least one substituted or unsubstituted cycloalkyl ring.

(5) A group having 1 to 20 carbon atoms and containing one substituted or unsubstituted aromatic ring. In addition, as the aromatic ring, a benzene ring, a pyridine ring, a naphthalene ring and the like can be mentioned, but from the viewpoint of availability of raw materials, a benzene ring seems to be preferable.

(6) A group having 1 to 30 carbon atoms and containing two or more substituted or unsubstituted aromatic rings. Further classification can be made into two aromatic rings, three aromatic rings, and four aromatic rings. Also in this case, a benzene ring is preferable as the aromatic ring from the viewpoint of availability of raw materials and the like.

(7) A group having 1 to 12 carbon atoms and containing a substituted or unsubstituted piperazine ring.

Further, a substituent (X) having a naphthyl urea structure
As with the joint group, should be appropriately selected depending on the melting point of the urea compound, the decomposition temperature, the solubility in a solvent, and the like, and is not particularly limited.
However, from the viewpoint of recording density, it seems more preferable that the substituent is a hydrogen atom (that is, unsubstituted) or that the substituent is an electron-withdrawing group.

Patents using a monourea compound as a heat-sensitive recording material are disclosed in JP-A-58-211496 and JP-A-59-184694.
And Japanese Patent Application Laid-Open No. 61-211085. These monourea compounds are urea compounds in which only one amino group of urea is substituted, and have a fundamentally different structure from the naphthyl-based urea compound of the present invention. In general, a heat-sensitive recording material is used by dispersing it in water. However, monourea compounds have some problems because they exhibit some water solubility, and they are still unsatisfactory in heat resistance (150 ° C.). Further, heat-sensitive recording materials using a dimerized urea-type compound are disclosed in JP-A-5-317152, JP-A-5-147357 and the like. This dimerized urea-type compound has a structure having a sulfonyl group adjacent to a urea group (Ar-SO ₂ -NH
-(C = O) -NH-). However, even in this dimerized urea compound, the heat resistance (150
° C).

However, the thermosensitive recording medium using the dimerized urea compound represented by the general formula (1) or (2) or the trimerized urea compound represented by the general formula (3) according to the present invention has a basic property. Excellent performance is excellent ground color stability against heat and solvents. That is, this recording
Even when placed in a high-temperature environment of 120 ° C. or higher, the ground color of the recording surface does not substantially develop color. However, when the high energy of the thermal head, which is usually 200 ° C. to 300 ° C., is instantaneously applied, a deep color develops. With regard to the heat resistance of the ground color, the common sense of heat-sensitive recording media up to now is that
Despite the fact that no color appears at all when exposed to a heat block of at least ℃, it is unlikely that a thermal head can record at a density sufficient for practical use. Had not been.

Since the heat-sensitive recording material of the present invention has such high heat resistance, it has been impossible to perform heat lamination in which the recording surface after heat-sensitive recording is thermally bonded with a plastic film or the like, which has been impossible in the past. Attaching a toner to the surface of the heat-sensitive layer and thermally fixing the toner by using it as a photographic transfer sheet;
Alternatively, toner can be adhered to the recording surface of a sheet on which heat recording has been performed, and heat fixing can be performed.

Further, in the heat-sensitive recording material of the present invention, management of the manufacturing process is extremely easy. In other words, conventionally, in the production of a thermosensitive recording medium, the drying step after the application of the thermosensitive coloring layer requires extremely strict temperature control so as to prevent the occurrence of ground coloration on the coated surface. there were. However, the heat-sensitive recording medium of the present invention does not generate ground color even when exposed to hot air of 120 ° C. in a dry state, so that drying at a high temperature is possible and the control range of the drying temperature can be greatly expanded. Therefore, a dramatic improvement in productivity can be expected.

The thermosensitive recording medium of the present invention can be prepared by contacting with a non-alcohol-based solvent, possibly because the dimerized or trimerized urea compound used has a very low solubility in organic solvents. There is almost no disappearance of the image area or change of the ground color, and the stability to the solvent is high. Therefore, discoloration due to the oil-based ink does not occur.

The present inventors have proposed a number of dimerization, or three,
While studying the thermal decomposition temperature and solubility in solvents for the quantified urea compound, we focused on the fact that the thermal decomposition temperature and solubility in solvents can be controlled by selecting the joint group that is the binding site. The use of at least one of the dimerized urea compound represented by the general formula (1) or (2) or the trimerized urea compound represented by the general formula (3) as a developer is described. By applying a certain amount of heat to a characteristic heat-sensitive recording medium with a hot roll, thermal head, hot stamp, or the like, or by irradiating light with a laser, a halogen lamp, or the like, or by using methanol, ethanol, or the like. The recorded image can be erased by contact with an alcohol-based solvent. Doyare - The - it is possible to re-record it Atere, ie we have found recording medium having a reversible recording property.

With respect to the reversible recording material, a dimerized urea compound in which the joint group is a linear alkylene group having 1 to 12 carbon atoms is preferable in terms of decoloring by heat roll. A recording medium using (for example, compound A-1) a color developer is exemplified.

A heat-sensitive recording material using these urea compounds as a color developer is colored by a thermal head or the like, and
The color can be erased by contact with a heat roll at a temperature of 00 ° C. to 200 ° C., and the erased surface can be printed again with a thermal head or the like. For example, those using compound A-1 as a developer showed good results.

The dimerized or trimerized urea compound used in the present invention itself has a high color developing ability as a color developer in a thermosensitive recording medium by itself, and this compound is used together with an electron-donating dye precursor as a support. The coated surface applied above does not substantially develop color even at 120 ° C., and exhibits basic characteristics of excellent ground color solvent resistance. In addition, the urea compounds of the present invention may, depending on the choice of
Some of them have a function of heat resistance of a ground color of not less than ° C or reversible recording (coloring / decoloring). All of these properties are new properties that have not been known so far, and these urea compounds are excellent materials that have both color developability and decolorability while being a single color developer. is there.

The general method for producing the thermosensitive recording medium of the present invention comprises dispersing (a) a dye precursor and (b) a dimerized urea compound or a trimerized urea compound as a color developer. This is a method in which each is dispersed together with a binder, and if necessary, auxiliaries such as fillers and lubricants are added to prepare a coating liquid, which is coated on a support by a usual method and dried. In addition, the dimerized urea compound or the trimerized urea compound of the present invention may be used alone or in combination.

As the dye precursor used in the heat-sensitive recording material of the present invention, those which are conventionally known in the field of heat-sensitive recording can be used, and are not particularly limited, but include triphenylmethane-based leuco dyes, Preferred are fluoran leuco dyes, fluorene leuco dyes and the like. 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 -Trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-fluoran 3-diethylamino-7-methyl-fluorane 3-diethylamino-7-chloro-fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3- Diethylamino-6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7-p-methylanilinofluoran 3-diethylamino-6-methyl-7- ( o, p-Dimethylanilino) fluoran 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- (pn-butylanilino)
Fluoran 3-diethylamino-6-methyl-7-n-octylaminofluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-ethoxyethyl-7-anilinofluoran 3-diethylamino- Benzo [a] fluoran 3-diethylamino-benzo [c] fluoran 3-diethylamino-6-methyl-7-benzylaminofluoran 3-diethylamino-6-methyl-7-dibenzylaminofluoran 3-diethylamino-7-di (P-methylbenzyl) aminofluorane 3-diethylamino-6-methyl-7-diphenylmethylaminofluoran 3-diethylamino-7-dinaphthylmethylaminofluoran 10-diethylamino-4-dimethylaminobenzo [a] fluoran 3 -Dibutylamino-6-methyl-fluoran 3-dibutylamino-6-methyl-7-chlorofluorane 3-dibutylamino-6- Methyl-7-anilinofluoran 3-dibutylamino-6-methyl-7-p-methylanilinofluoran 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3-dibutyl Amino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-dibutylamino-6-methyl-7- (o-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (p-chloroanilino ) Fluoran 3-dibuethylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-dibuethylamino-6-methyl-7- (pn-butylanilino) fluoran 3-dibutylamino-6-methyl- 7-n-octylaminofluoran 3-dibutylamino-6-chloro-7-anilinofluoran 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran 3-di-n-pentylamino-6-methyl -7-anilinofluoran 3-di-n-pentylamino-6-methyl-7- (o, p-di Methylanilino) fluoran 3-di-n-pentylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-di-n-pentylamino-6-methyl-7- (o-chloroanilino) fluoran 3-di n-pentylamino-6-methyl-7- (p-chloroanilino) fluoran 3-di-n-pentylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-pyrrolidino-6-methyl-7- Anilinofluoran 3-piperidino-6-methyl-7-anilinofluoran 3- (N-methyl-Nn-propylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-Nn- Propylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-iso-propylamino) -6-methyl-7-
Anilinofluoran 3- (N-ethyl-Nn-butylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-iso-butylamino) -6-methyl-7-anilino Fluoran 3- (N-ethyl-Nn-hexylamino) -6-methyl-7-p-
Methylanilinofluoran 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (o,
p-Dimethylanilino) fluoran 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (m-
Trifluoromethylanilino) fluoran 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (o-
Chloroanilino) fluoran 3- (N-ethyl-N-iso-amylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-iso-amylamino) -6-chloro-7-anilinofur 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-anilinofluoran 3- (N-cyclohexyl-N-methylamino) -6-methyl-7
-Anilinofluoran 3- (N-cyclohexyl-N-methylamino) -7-anilinofluoran 3- (N-ethyl-N-3-methoxypropylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-3-ethoxypropylamino) -6-methyl-7-anilinofluoran 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 3- (4 ''-aminostilbuldyl-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) -Four-
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) fluoran- γ- (2′-nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (3′-nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (4′-nitro) Anilinolactam 3,6-bis (diethylamino) fluoran-γ-anilinolactam

These dye precursors may be used alone or in combination of two or more. The fluoran-based dye precursor is preferably used in the present invention, since the color developing property and the stability of the ground color are enhanced particularly on the basic function of the heat-sensitive recording medium. When importance is placed on thermal stability, naturally, a dye precursor having a high melting point and a high decomposition temperature is preferred. When reversible recording is important, use a dye precursor such as 3-diethylamino-7- (m-trifluoromethylanilino) fluoran, which has low image stability and a structure that can withstand repeated use and has a high decomposition temperature. Is good.

As the binder that can be used in the present invention, fully silicified polyvinyl alcohol having a polymerization degree 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, other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and ethyl cellulose, cellulose derivatives such as acetyl cellulose, polyvinyl chloride, poly Vinyl acetate, polyacrylamide, polyacrylate,
Polyacrylamide, polyacrylate, polyvinyl butyral, polystyrene and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, cumarone resin can be exemplified, among these polyvinyl Alcohol-based binders are desirable in terms of dispersibility, binder properties, and thermal stability of the ground color. In the case of reversible recording, a binder that can withstand repeated use and has little deterioration is preferable. These binders are used in a state of being dissolved in a solvent such as water, alcohol, ketone, ester, or hydrocarbon, or emulsified in water or another medium, or used in a state of being dispersed in a paste form, and used together according to required quality. You can do it.

In the present invention, when a thermosensitive recording medium having particularly high ground color thermal stability is produced, it is generally preferable not to use a sensitizer. If a sensitizer is used, these are melted at a temperature at about the time of drying, and the dye precursor and the color developer react with each other, so that the background color tends to develop. However, on the other hand, the sensitizer enhances the decoloring property, and when the decoloring property, that is, the reversible recording property is more important than the thermal stability of the ground color, these may be used. Sensitizers used for that purpose include 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-tolyl Ether, m-terphenyl, 1,2-diphenoxyethane, 1,2-bis (m-tolyloxy) ethane, 1,5-bis (p-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, oxalic acid Examples thereof include di (p-methylbenzyl) and di (p-chlorobenzyl) oxalate.

The filler used in the present invention includes inorganic fillers such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, zinc oxide, titanium oxide, zinc hydroxide and aluminum hydroxide, and polystyrene-based organic fillers. Fillers, styrene / butadiene-based organic fillers, styrene / acrylic-based organic fillers, hollow organic fillers and the like.

In addition, a releasing agent such as a fatty acid metal salt, a lubricant such as a wax, a benzophenone-based or benzotriazole-based ultraviolet absorber, a water-proofing agent such as glyoxal, a dispersant, and an antifoaming agent. Can also.

The amount of the (a) dye precursor of the present invention and (b) a dimerized or trimerized urea compound, and the types and amounts of other various components are determined according to the required performance and recording suitability. Although not particularly limited, usually 1 to 8 parts of a dimerized or trimerized urea compound and 1 to 20 parts of a filler with respect to 1 part of the dye precursor, and The content is 10 to 25% by weight. When used repeatedly, such as in a reversible recording medium, it is desirable that the composition be as simple as possible. These materials are ball mills,
It is pulverized to a particle size of several microns or less by a pulverizer such as an attritor or a sand grinder or a suitable emulsifying apparatus, and a coating liquid is prepared by adding a binder and various additives according to the purpose. The intended heat-sensitive recording medium by applying a coating solution having the above composition to any support such as paper, synthetic paper, nonwoven fabric, metal foil, plastic film, plastic sheet, or a composite sheet obtained by combining these. Is obtained.

Further, an overcoat layer made of a polymer substance is provided on the thermosensitive coloring layer for the purpose of enhancing the storage stability.
An undercoat layer of a filler-containing polymer substance or the like can be provided below the heat-sensitive layer for the purpose of enhancing color sensitivity.

The heat-sensitive recording medium of the present invention may be provided with a transparent and strong protective coating by thermally laminating a plastic film, taking advantage of high ground color stability. For example,
Even after thermal recording, a heat-resistant card can be easily prepared using a commercially available simple laminating machine.

Among the heat-sensitive recording materials of the present invention, a recording material having a decoloring function is useful as a reversible recording material (a rewritable recording material or a rewritable recording material) or as a simple display material. However, in the latter case, recording and erasing must be performed at almost the same speed.

There are two methods for decoloring the thermosensitive recording medium of the present invention. One method is to erase a recorded image by heat using a hot roll, a thermal head, a hot stamp, a carbon dioxide laser, a semiconductor laser, sunlight, a halogen lamp, or the like. For example, in the case of a hot roll, the decolorizing temperature is between 100 ° C and 200 ° C and the feed rate is
45mm / sec is appropriate. Another method is a method of erasing a recorded image by bringing an alcohol-based solvent into contact.

In the heat-sensitive recording medium of the present invention, the heat-sensitive recording layer may contain a light absorbing agent which absorbs light and converts it into heat. 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, a light absorber described in JP-A No. 2-206583, Japanese Patent Application No. 5-30954 or the like can be used. Examples of the heated reaction product of a thiourea derivative / copper compound include graphite, copper sulfide, lead sulfide, molybdenum trisulfide, black titanium, etc. described in JP-A-3-86580, and carbon black.

On the other hand, when a semiconductor laser is used as a light source for recording, a light absorbing agent is used as disclosed in JP-A-54-4142.
JP, JP-A-58-94494, JP-A-58-209594, JP-A-2-217287, JP-A-3-73814, etc., polymethine dyes (cyanine dyes),
Azorhenium dye, pyrylium dye, thiopyrylium dye, squarylium dye, croconium dye, dithiol complex, mercaptophenol metal complex dye, mercaptonaphthol metal complex dye, phthalocyanine dye, naphthalocyanine dye Dyes, triarylmethane-based dyes, immonium-based dyes, diimmonium-based dyes, naphthoquinone-based dyes, anthraquinone-based dyes, metal complex-based dyes, and the like can be given. Further, the light absorbing agents listed in the case of a light source having a continuous wavelength can be used in the same manner.

More specifically, examples of polymethine dyes (cyanine dyes) include Indocyanine Lin (manufactured by Daiichi Pharmaceutical Co., Ltd.), NK-2014 (manufactured by Japan Photographic Dye Laboratories), and NK -2612 (manufactured by Japan Photographic Dye Laboratories), 1,1,1
5,5-tetrakis (p-dimethylaminophenyl) -3-methoxy-1,4-pentadiene, 1,1,5,5-tetrakis (p-diethylaminophenyl) -3-methoxy-1,4-pentadiene, etc. NK-277 as a squarylium dye
2 (manufactured by Japan Photographic Dye Laboratories, Inc.). Examples of the dithiol complex include a toluene dithiol nickel complex, a 4-tert-butyl-1,2-benzenedithiol nickel complex, and a bisdithiobenzyl nickel complex. , Bis (4-ethyldithiobenzyl) nickel complex, bis (4-n-propyldithiobenzyl) nickel complex and the like. Examples of the immonium dye or diimmonium dye include:
IRG002 (Nippon Kayaku Co., Ltd.), IRG022 (Nippon Kayaku Co., Ltd.)
NIR-14 (manufactured by Yamamoto Kasei Co., Ltd.) as an example of a naphthalocyanine dye, and IR-750 (Nippon Kayaku Co., Ltd.) as an anthraquinone dye.
Manufactured). These light absorbers may be used alone or in combination of two or more.

These light absorbers are used by simply mixing (a) various materials necessary for a recording medium and (b) a method of
As described in JP 7287, etc., a method in which a light absorber is melted and mixed and dissolved or dispersed in advance in various materials necessary for a recording medium, or (c) a method necessary for a recording medium The light absorbing agent may be dissolved or dispersed in the material in advance with a solvent, and the dissolved or dispersed mixture may be used by a method using the solvent after removing the solvent.
The light absorber may be co-dispersed (simultaneously mixed and dispersed) with a developer and / or a sensitizer, or a dye precursor and / or a sensitizer.

The basic properties (eg, ground color stability such as heat resistance and solvent resistance) of the heat-sensitive recording material of the present invention are not significantly changed even when a light absorbing agent is contained. That is, thermal lamination and toner recording are possible even when a light absorbing agent is contained. The same was true for the additional function (reversible recording property). However, when using a sensitizer,
There was a tendency for heat resistance to decrease.

[0063]

The novel naphthyl-based dimerized urea compound or the trimerized urea compound according to the present invention is a developer having excellent color development as a basic function and excellent ground color stability against heat and solvents. Among them, there are color developers having reversible recording properties. The clear reasons for ground color stability and reversible recording have not yet been elucidated. However, it is estimated as follows.

The dimerized urea compound of the present invention, or 3
The structure of the quantified urea compound changes as in the following formula depending on conditions. Since this change is a phenomenon similar to keto / enol tautomerism, it is referred to herein as keto-enolization for convenience.

Embedded image

It is considered that enolization is necessary for the dimerized urea compound or the trimerized urea compound to function as a color developer. A high temperature is required for enolization, and the temperature of the thermal head instantaneously rises to 200 to 300 ° C. Therefore, enolization occurs in the urea compound that comes into contact with the thermal head, causing the color developing function to occur and the formation of the dye precursor. It is thought that the lactone ring is cleaved to develop color. Therefore, the urea compound does not change until the temperature at which enolization occurs and does not react with the dye precursor, so that the ground color remains white, which seems to be the reason for the high heat resistance. Also,
Compared with the monourea compound, in the case of the dimerized urea compound or the trimerized urea compound, the number of active hydrogens is increased, so that it is considered that good color developability is obtained.

On the other hand, if the enol compound formed in this way is eliminated for some reason and ketoized, it is considered that discoloration may occur, and the enol compound is brought into contact with an appropriate temperature and calorie, or with an alcohol solvent. It is thought that ketoization occurs and discoloration occurs. Since enolization and ketoization occur under completely different conditions, enolization and ketoization can be repeated under each condition, which would enable reversible recording.

The reason why the ground color does not change when writing with an oil-based ink is that the dimerized urea compound or the trimerized urea compound of the present invention has an extremely low solubility in the solvent used in the oil-based ink. It is considered that the mixing of the dye precursor and the developer does not substantially occur even when contact is made with the dye.

[0068]

EXAMPLES In the following description, parts and% indicate parts by weight and% by weight, respectively.

[Examples 1 to 5] As described below, a thermosensitive recording material was produced using the following dye precursor as a dye precursor and Compound A-1 as a developer. (See Table 1) (Dye precursor) ODB: 3-N, N-diethylamino-6-methyl-7-anilinofluoran ODB-2: 3-N, N-dibutylamino-6-methyl-7-ani Rinofluoran CVL: 3,3-bis (p-dimethylaminophenyl) -6-
Dimethylaminophthalide NEW-Blue: 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-
Azaphthalide I-red: 3,3-bis (1-ethyl-2-methylindole
-3-yl) phthalide That is, first, the developer dispersion (solution A) and the dispersion of the dye precursor (solution B) having the following composition were ground by a sand grinder to an average particle diameter of 1 micron. (Solution A: developer dispersion) Compound A-1 6.0 parts 10% aqueous solution of polyvinyl alcohol 18.8 parts Water 11.2 parts (Solution B: dye precursor dispersion) 2.0 parts of each of the above dye precursors 10 parts 10% aqueous solution of polyvinyl alcohol 4.6 Part Water 2.6 parts Next, a coating liquid was prepared by mixing the following liquid A (color developer dispersion), liquid B (dye precursor dispersion), and kaolin clay dispersion. Liquid A: developer dispersion liquid 36.0 parts Liquid B: dye precursor dispersion liquid 9.2 parts Kaolin clay (50% dispersion liquid) 12.0 parts This coating liquid was applied on one side of a 50 g / m ² base paper 6.0 g /
coating and drying so as to m ^2, was treated as smoothness of the sheet supercalendered is 500-600 seconds,
A thermosensitive recording medium was produced.

Examples 6 to 8 As described below, heat-sensitive recording media were prepared in the same manner as in Example 1 except that compounds A-6, A-7, and A-23 were used as developers. did. (See Table 1) (Solution C: developer dispersion) Compound A-6, A-7, or A-23 6.0 parts 10% aqueous solution of polyvinyl alcohol 18.8 parts Water 11.2 parts Then, at the following ratio, Solution C ( (Developer dispersion), the ODB dispersion used in Example 1, and the kaolin clay dispersion were mixed to form a coating liquid. Liquid C: developer dispersion 36.0 parts ODB dispersion used in Example 1 9.2 parts Kaolin clay (50% dispersion) 12.0 parts This coating liquid was applied on one side of a 50 g / m ² base paper 6.0 g. /
coating and drying so as to m ^2, was treated as smoothness of the sheet supercalendered is 500-600 seconds,
A thermosensitive recording medium was produced.

[Comparative Examples 1 to 7] Thermosensitive recording media for Comparative Examples were prepared in the same manner as in Examples 1 to 8, using the following known compounds as developers. . (See Table 1) (Known developer compound) Bisphenol A (B1) Bisphenol S (B2) 4-hydroxy-4'-iso-propoxydiphenylsulfone (B3) 4-hydroxy-4'-n -Butyroxydiphenyl sulfone (B
4) Phenyl urea (B5) described in JP-A-58-211496 Dimerized urea (B6) described in JP-A-5-147357 Amidophenol derivative (B7)

[0072]

Embedded image

That is, a dispersion of each of the above known color developer compounds having the following composition was ground to a mean particle size of 1 μm with a sand grinder. (D solution: developer dispersion) Known developer compounds (B1 to B7) 6.0 parts 10% aqueous solution of polyvinyl alcohol 18.8 parts Water 11.2 parts Then, at the following ratio, D solution (developer dispersion), The ODB dispersion (solution B) used in Example 1 and the kaolin clay dispersion were mixed to form a coating liquid. Liquid D: developer dispersion 36.0 parts ODB dispersion used in Example 1 9.2 parts Kaolin clay (50% dispersion) 12.0 parts This coating liquid was applied on one side of a 50 g / m ² base paper 6.0 g. /
coating and drying so as to m ^2, was treated as smoothness of the sheet supercalendered is 500-600 seconds,
A thermosensitive recording medium was produced.

(Evaluation of Thermosensitive Recording Material) The obtained thermosensitive recording material was subjected to a recording test using a thermal printer, a thermal stability test of a ground color, a thermal lamination test, and an oil-based ink suitability test.

[Recording Test (Dynamic Color Density)]: In order to check the recording suitability, recording was performed on the produced thermal recording medium using a word processor (RUPO-90F (manufactured by Toshiba)) at the maximum applied energy. The recording part is recorded with a Macbeth densitometer (RD-9
14, using an amber filter. 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.

[Ground Thermal Stability Test (Static Color Density)]: To check the thermal stability of the ground color of the recording sheet, 1
The prepared thermosensitive recording medium was pressed against a hot plate heated at 20 ° C. and 150 ° C. at a pressure of 10 g / cm ² for 5 seconds, and the recording medium was measured with a Macbeth densitometer. In this case, the smaller the Macbeth value, the lower the degree of coloring of the ground color, and the higher the thermal stability of the ground color.

[Thermal Laminate Test (Preparation of Laminate Recorded Body)]: Simple Laminate Apparatus (MS Pouch H-140)
The obtained thermal recording medium was sandwiched between pouch films to produce a laminated thermal recording medium, and the ground color portion was measured with a Macbeth densitometer. In this case, a smaller Macbeth value indicates that the ground color is more stable. In other words, it indicates that lamination can be performed without causing color development. The heat-sensitive recording material using the dimerized or trimerized urea compound of the present invention could be laminated while the ground color was stable.

[Oil-based ink suitability test (discoloration test of ground color with oil-based ink)]: Oil-based red magic ink No. 500
(Manufactured by Teranishi Chemical Co., Ltd.), and the degree of discoloration with respect to the original red color was visually observed by writing on the produced thermal recording medium. ◎: No discoloration ○: Almost no discoloration △: Slight discoloration ×: Significant discoloration

The evaluation results of Examples 1 to 8 using the dimerized or trimerized urea compound of the present invention as a developer and Comparative Examples 1 to 7 using a known developer compound as a developer are shown below. The results are shown in Table 1.

[0080]

[Table 1]

Next, a reversible recording test was performed on the obtained thermosensitive recording medium. [Reversible recording test]: In the same manner as in the recording test, the obtained thermosensitive recording medium was recorded by a word processor, and the recorded thermosensitive recording medium was heated at a speed of 180 mm between heat rolls at a speed of 30 mm.
The recording portion and the ground color portion were measured with a Macbeth densitometer. In this case, the lower the Macbeth density of the recording portion, the higher the decoloring property. Thereafter, recording was performed again with the above-mentioned word processor, and the Macbeth density of the recording portion was measured.

Table 2 shows the evaluation results of Examples in which the dimerized or trimerized urea compound of the present invention was used as a developer, and Comparative Examples in which a known developer compound was used as a developer.

[0083]

[Table 2]

Example 9 The thermosensitive recording medium of Example 4 was repeatedly subjected to a reversibility test by a heat roll 100 times. The Macbeth densities of the 100th recording portion and the ground color portion were 0.78 and 0.14, respectively.

Example 10 In the thermal recording medium of Example 6, after recording with a word processor, the recording surface was wiped off with ethanol and the Macbeth density of the recording portion was measured.
It was 0.27.

[Example 11] When the thermal recording medium of Example 1 was subjected to toner recording with a copying machine (manufactured by NP6060 Canon Inc.), no change was observed in the ground color, and printing was performed. We were able to.

Example 12 As described below, 3-N, N-diethylamino-6-methyl-7-anilinofluorane (alias: ODB) was used as a dye precursor and the present invention was used as a color developer. The compound A-1 was used as the light absorbing agent, and a bismuththiobenzylnickel complex and a sensitizer were used as a heat-melting material to produce a thermosensitive recording medium. That is, first, 94 parts of 4-biphenyl-p-tolyl ether was added with the bidithiobenzylnickel complex 6
The mixture was heated to 100 to 150 ° C., melted and mixed, and then pulverized to obtain a light absorber. Then, a light absorbent dispersion having the following composition was ground by a sand grinder to an average particle diameter of 1 micron. (Solution E: Light Absorbent Dispersion) Light Absorber 4.0 parts 10% aqueous polyvinyl alcohol solution 10.0 parts Water 6.0 parts Then, at the following ratio, the developer dispersion liquid used in Example 1 (Solution A), The ODB dispersion used in Example 1 (B
Solution), solution E (light absorber dispersion), and kaolin clay
Were mixed to form a coating solution. Liquid A (developer dispersion liquid) 36.0 parts Liquid B (dye precursor dispersion liquid) 9.2 parts Liquid E (light absorber dispersion liquid) 20.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts This coating liquid is 50 g / m2. the coating amount on one side of ² of the base paper 6.0g /
coating and drying so as to m ^2, was treated as smoothness of the sheet supercalendered is 500-600 seconds,
A thermosensitive recording medium was produced. Japanese Patent Laid-Open Publication No.
Laser light irradiation was performed using a laser plotter device described in JP-A-3-239598, and the recorded portion was measured with a Macbeth densitometer. The light irradiation conditions were as follows: As a recording light source, a semiconductor laser LT015M with an oscillation wavelength of 830 nm and an output of 30 mW
D (Sharp Corporation), an aspheric plastic lens with a numerical aperture of 0.45 and a focal length of 4.5 mm as a light collection lens
Using AP4545 (manufactured by Konica Corporation), recording speed 50mm / s
The recording was performed at ec and a recording interval of 50 microns, and a solid recording of 1 cm in length and width was obtained. The Macbeth density of the recording portion was 1.09.

[0088]

As described above, the naphthyl-based dimerized urea compound or trimerized urea compound of the present invention has substantially no change in ground color at an ambient temperature in the range of 120 to 150 ° C. Nevertheless, it can be seen that this is an epoch-making developer capable of obtaining a recording of image density sufficient for practical use by a thermal head or the like. Therefore, the following points can be mentioned as effects of the present invention.

(1) A heat-sensitive recording material which is more excellent in storage stability such as heat resistance and solvent resistance than a conventional heat-sensitive recording material. (2) The thermosensitive recording medium can be used under severe conditions that could not be used until now (for example, temperature conditions in the range of 90 ° C. to 150 ° C.). (3) Since discoloration does not occur when writing with an oil-based ink, it is possible to freely write on a thermosensitive recording medium using these writing tools. (4) The thermal recording medium can be easily thermally laminated by a simple laminating device or the like. Cards and the like can be easily made. (5) Since the ground color is stable even after passing through a heat roll, toner recording can be performed on a thermosensitive recording medium.

For a thermosensitive recording medium having a decoloring function, (6) a new recording system capable of repeating recording and erasing with a color tone is possible, and resources can be saved because it can be used many times. (7) There are some which can be erased only by passing through a heat roll, and strict temperature control is not required at the time of erasing. (8) Unlike a liquid crystal or the like, it can be used as a simple display element for recording and erasing using different heat energy.

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

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tosumi Satake 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. Central Research Laboratory (56) References JP-A-63-218394 (JP, A) JP-A-62-42883 (JP, A) JP-A-7-68945 (JP, A) JP-A-6-227142 (JP, A) JP-A-3-207688 (JP, A) JP-A-2-217287 (JP, A) JP-A-63-239083 (JP, A) JP-A-63-81082 (JP, A) JP-A-62-202785 (JP, A) JP-A-5-58056 (JP, A) JP-A-3-133626 (JP, A) JP-A-2-29393 (JP, A) JP-A-63-68856 (JP, A) JP-A-5-229253 (JP, A) JP-A-5-177931 ( JP, A) JP-A-4-43074 (JP, A) JP-A-4-344287 (JP, A) JP-A-5-254244 ( P, A) JP Akira 60-224585 (JP, A) JP Akira 56-166093 (JP, A) JitsuHiraku Akira 57-185567 (JP, U) (58 ) investigated the field (Int.Cl. ^7, DB name) B41M 5/30 G03G 7/00 101 CA (STN) REGISTRY (STN)

Claims (6)

(57) [Claims] 1. A thermosensitive recording medium having a thermosensitive coloring layer containing a colorless or pale-colored dye precursor and a developer which reacts upon heating to form the dye precursor, wherein the developer is represented by the following general formula: A heat-sensitive recording material, which is a urea compound represented by (1), (2) or (3), wherein the heat-sensitive coloring layer contains at least one kind of the urea compound. Embedded image (Where X represents an alkyl group having 1 to 6 carbon atoms, a halogen atom, or a hydrogen atom. Y represents a divalent group having up to 30 carbon atoms, and Z represents a divalent group having up to 30 carbon atoms. Represents a trivalent group composed of 30 or less.) 2. The heat-sensitive recording medium according to claim 1, wherein the recording layer contains a light absorbing agent that absorbs light and converts it into heat. 3. A heat-sensitive recording card obtained by laminating a heat-sensitive recording medium according to claim 1 with a plastic film. 4. An electrophotographic transfer sheet using the heat-sensitive recording medium according to claim 1. 5. A reversible recording method, wherein after recording on the thermosensitive recording medium according to claim 1 or 2, heat is applied to the recording section to erase the recorded image, and the thermosensitive recording is performed again. 6. After recording on the thermosensitive recording medium according to claim 1 or 2, the recording image is erased by bringing the recording portion into contact with an alcohol-based solvent, and the thermosensitive recording is performed again. Reversible recording method.