JPH07164757A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance the stability of a ground color and reversible recording properties, in the thermal recording material having a thermal color forming layer containing a dye precursor and a coupler, by using a specific urea compd. as the coupler to add the same to the thermal color forming layer. CONSTITUTION:A thermal recording material having a thermal color forming layer containing a colorless or light-colored dye precursor and a coupler reacting with the dye precursor at the time of heating to develop a color develops a color by instantaneous chemical reaction started by heating due to a thermal head, a hot stamp or laser beam to obtain visible recording. In this case, a urea compd. represented by either one of formulae I, II, III (wherein X is a 1-6C alkyl group, a halogen atom or a hydrogen atom, Y is a divalent group having 30 or less carbon atoms and Z is a trivalent group having 30 or less carbon atoms) is used as the coupler to be added to the thermal color forming layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material excellent in stability of background color and a heat-sensitive recording material having reversible recording property with vivid color tone.

[0002]

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

The thermosensitive recording medium is applied to a wide range of fields such as a measuring recorder, a computer terminal printer, a facsimile, an automatic ticket vending machine and a bar code label. However, recently, the diversification of recording devices for thermal recording media,
Higher performance is being promoted, and therefore, the quality required for the thermal recording material is also higher. For example, from the viewpoint of speeding up recording, it is possible to obtain a clear color image with high density even with smaller thermal energy. On the other hand, from the viewpoint of storage stability of the recording material, light resistance,
It is required to have excellent oil resistance, water resistance and solvent resistance.

On the other hand, as the method of recording on plain paper such as the electrophotographic method and the ink jet method has become widespread, thermal recording is often compared with the recording on plain paper. For example, it is required that the stability of the recording portion (image) and the stability of the non-recording portion (background color portion) before and after recording (hereinafter referred to as background color stability) approach the quality comparable to plain paper recording. ing. Particularly, as a basic function of heat-sensitive recording, ground color stability against heat and solvent has been required, and so to speak, it has been desired to be heat-sensitive only at the time of recording and insensitive otherwise.

Regarding the background color stability of the thermal recording material, for example,
Japanese Patent Laid-Open No. 4-353490 discloses a heat-sensitive recording material 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.

On the other hand, the rapid increase in the amount of recording materials consumed with the construction of various networks and the spread of facsimiles and copying machines causes social problems such as dust disposal. As one idea for dealing with this problem, a reversible recording medium capable of repeating recording and erasing is drawing attention.

Regarding the recording medium having reversible recording property, it is detailed in a review article such as the Paper and Paper Cooperative Journal 47 11 (1993) p1309-1322. For example, JP-A-3-230993 and JP-A-4-366682 are available. Discloses a recording material that utilizes the reversible change of a recording material between a transparent state and a cloudy state depending on a given temperature, and a recording material that utilizes the reversibility of a thermochromic material and a reversible dye of a leuco dye. A recording body using various color tone changes has been proposed.

[0008]

The background color stability of the thermosensitive recording medium disclosed in Japanese Patent Laid-Open No. 4-353490 is 95% in a dryer.
When processed at 5 ° C for 5 hours, the Macbeth density of the ground color is about 0.11, which shows considerable stability, but is still insufficient, and it is not possible to heat-laminate the colored surface with a plastic film. It was

Regarding a reversible recording material, a recording material utilizing the reversible change of the recording material between a transparent state and a cloudy state (in other words, a recording material utilizing a change in transparency of the recording material) is (1) Poor image clarity,
(2) There are drawbacks such as slow white turbidity (decoloring) speed and (3) temperature control required for erasing. Also, with this recording medium, in order to create contrast with white turbidity and transparency,
There is no problem in using it as a transparent recording material such as OHP, but when the recording material is coated on a white opaque support like a conventional thermal recording material, it is necessary to provide a colored layer on the back. is there. Therefore, the coating layer (the layer that reversibly changes to a transparent / white turbid state) on the colored layer should have a thin layer in order to obtain contrast, in other words, to clearly show the color of the colored layer (color of the base). On the other hand, on the other hand, in order to appear white, a thick layer is preferable, and strictness of the coating layer is required.

In a reversible recording medium using a thermochromic material, most of the thermochromic material is
There is a problem that the memory property is poor and continuous heat supply is required to maintain the color-developed state.

On the other hand, reversible recording materials using a leuco dye as a color-forming source are disclosed in JP-A-60-193691 and JP-A-60.
Although reversible recording bodies are disclosed in Japanese Patent Publication No. 257289, these recording bodies have a problem in practical use because they are decolorized with water or water vapor. In addition, Japanese Patent Laid-Open No. 2-18
No. 8293, JP-A-2-188294, and the like, a material having a simple layer structure and having a color developing effect and a color reducing effect for reversibly changing the color tone of a leuco dye only by controlling thermal energy (a color reducing agent). ) Is disclosed. However, in this color-developing / reducing agent, the decoloring process has already contributed in the color-developing process, so that there is a problem that the color density is low. Also recently, Ja
In pan Hardcopy '93, Yokota et al. announced a recording medium using an amidophenol derivative having a long-chain alkyl, but this recording medium also requires a temperature control for erasing. There was a flaw.

Therefore, it is an object of the present invention to provide a heat-sensitive recording material having an excellent ground color stability against heat and solvent as a basic function. As an additional function, record-
An object of the present invention is to provide a heat-sensitive recording material having a reversible recording property that can be erased and re-recorded.

[0013]

The above problems were solved by a thermosensitive recording medium using a naphthylurea type developer having a structure which is completely different from that of a general phenol type developer.

The present invention relates to a thermosensitive recording medium having a thermosensitive color developing layer containing a colorless or pale color dye precursor and a developer which reacts when heated to develop the color of the dye precursor. It relates to a urea compound represented by the general formula (1), (2) or (3), wherein the thermosensitive color developing layer contains at least one kind of the urea compound.

[0015]

[Chemical 2] (Here, X represents an alkyl group having 1 to 6 carbon atoms, a halogen atom, or a hydrogen atom. Y is a divalent group having 30 or less carbon atoms, and Z is a divalent group. Represents a trivalent group consisting of 30 or less.)

The urea compound represented by the general formula (1), (2) or (3) has a naphthylurea structure (R-NH-C = O).
-NH-, R = -Naphtyl) is a compound having two or three. The urea compound of the general formula (1) is a compound in which two naphthylurea structures are directly linked, and the urea compound represented by the general formula (2) or (3) is a compound of 2 to 3 naphthylureas. The structure is a compound connected 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, for example, by reacting an amine with an isocyanate compound.

[Chemical 3]

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

[Chemical 4]

When the monoisocyanate compound is reacted with diamines, the diamines include carbohydrazide, ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-diaminobutane, 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, ethylene glycol bis (3-aminopropyl) ether Tell, 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, sulfurized 4,4'-diaminodiphenyl, 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 '
-Methylenedianiline, 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 thereof include isophoronediamine, and examples of the monoisocyanate compound include naphthyl 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-naphthalene diisocyanate (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)
, As monoamines, 1-naphthylamine, 2-
Examples thereof include naphthylamines such as naphthylamine, 2-methyl-1-naphthylamine, and 2-chloro-1-naphthylamine, which can be selected in any combination.

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

On the other hand, the trimerized urea compound represented by the general formula (3) is 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 triisocyanate is reacted with a monoisocyanate compound, 1,2,4-
Triaminobenzene, tris (2-aminoethyl) amine, melamine, 2,4,6-triaminopyrimidine, triamterene and the like are mentioned as the monoisocyanate compound, and the compounds mentioned above can be mentioned, and any combination thereof can be selected. be able to. On the other hand, in the case of reacting a monoamine with a triisocyanate compound, triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, lysine ester triisocyanate, 1 is used as the triisocyanate compound. , 6,11-Undecane triisocyanate, 1,8-diisocyanate-4
-Isocyanate methyl octane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, etc., and the monoamines include the above-mentioned compounds. You can choose.

Specific examples of the urea compound represented by the general formula (1), (2) or (3) include the following compounds.

[0025]

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

The joint group should be appropriately selected depending on the melting point of the urea compound, the decomposition temperature, the solubility in a solvent, etc., 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 straight-chain 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 each having 1 to 12 carbon atoms and connected 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 connected by nitrogen atom)

[Chemical 9] (Where L1 = 1 to 11 and M1 = 1 to 11 are integers, and L1 + M1 = 2
~ 12. )

[Chemical 10] (Where L2 = 1-10, M2 = 1-10, N2 = 1-10 integers, L2
+ M2 + N2 = 3 to 12. )

[Chemical 11] (Here, L3 = 1-9, M3 = 1-9, N3 = 1-9, Q3 = 1-9, and L3 + M3 + N3 + Q3 = 4-12.)

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

[Chemical 13] (Here, L5 = 1 to 7, M5 = 1 to 2, and N5 = 1 to 7 are integers, and L4 + 4 × M4 + N4 = 6 to 12.) (When connected by oxygen atoms)

[Chemical 14] (Where L6 = 1 to 11 and M6 = 1 to 11 are integers, and L6 + M6 = 2 to 12
Is. )

[Chemical 15] (Where L7 = 1-10, M7 = 1-10, N7 = 1-10 integers, L7
+ M7 + N7 = 3 to 12. )

[Chemical 16] (Here, L8 = 1 ~ 9, M8 = 1 ~ 9, N8 = 1 ~ 9, R8 = 1 ~ 9, L8 + M8 + N8 + Q8 = 4 ~ 12.) 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. Examples of the aromatic ring include a benzene ring, a pyridine ring, a naphthalene ring, and the like. From the availability of raw materials, the 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. If it is further classified, it can be divided into two aromatic rings, three aromatic rings, and four aromatic rings. Also in this case, the benzene ring is preferable as the aromatic ring in view of availability of raw materials.

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

The substituent (X) having a naphthylurea structure
Similarly to 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 that the case where the substituent is a hydrogen atom (that is, unsubstituted) or the case where the substituent is an electron-withdrawing group is more preferable.

Patents using a monourea compound in a heat-sensitive recording material are disclosed in JP-A-58-211496 and JP-A-59-184694.
JP-A No. 61-211085 and the like. These monourea compounds are urea compounds in which only the amino group portion on one side of urea is substituted, and their structures are basically different from the naphthyl-based urea compound of the present invention. Generally, a heat-sensitive recording material is used by dispersing it in water, but a monourea compound is problematic because it exhibits some water solubility, and is still unsatisfactory in terms of heat resistance (150 ° C.). Further, a heat-sensitive recording material using a dimerized urea type compound is disclosed in JP-A Nos. 5-1317152 and 5-147357. This dimerized urea type compound has a structure having a sulfonyl group adjacent to a urea group (Ar—SO ₂ —NH
It is characterized by-(C = O) -NH-). However, even with this dimerized urea compound, the heat resistance (150
There was a problem in terms of (° 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) of the present invention is basically The ground color stability against heat and solvent is excellent. That is, this recording body
Even if it is placed in a high temperature environment of 120 ° C or higher, the ground color of the recording surface does not substantially develop. However, when the high energy of the thermal head, which is usually 200 ° C to 300 ° C, is applied instantaneously, it develops a dark color. Regarding the heat resistance of the background color, it is common knowledge of thermal recording materials so far that the surface of the thermal recording layer is
It is unthinkable that a thermal head can record a density that is practical enough, even though a color is not applied at all when exposed to a heat block above ℃. It wasn't done.

Since the heat-sensitive recording material of the present invention has such high heat resistance, it is impossible to carry out heat lamination in which the recording surface after heat-sensitive recording is heat-bonded with a plastic film or the like, which has been impossible in the past. To be used as a photographic transfer sheet to attach toner to the surface of the heat-sensitive layer for thermal fixing,
Alternatively, it has become possible to attach a toner to the recording surface of the sheet on which heat-sensitive recording has been carried out and to fix it by heat.

Further, the thermal recording material of the present invention is extremely easy to control the manufacturing process. That is, conventionally, in the production of a thermosensitive recording medium, the drying step after coating the thermosensitive coloring layer requires very strict temperature control so that the background coloring of the coated surface does not occur, and therefore, there is a limit to high-speed coating. there were. However, the heat-sensitive recording material of the present invention does not develop the ground color even when hot air of 120 ° C. is applied in the dry state, so that it can be dried at a high temperature and the control range of the drying temperature can be greatly expanded. Therefore, it is possible to expect a dramatic improvement in productivity.

Further, in the heat-sensitive recording material of the present invention, the dimerized or trimerized urea compound used has extremely low solubility in an organic solvent, and it may be brought into contact with a solvent other than an alcohol solvent. In addition, the image area hardly disappears or the background color does not change, and the stability to the solvent is high. Therefore, discoloration due to the oil-based ink does not occur.

We have a large number of dimerizations, or 3
Regarding quantified urea compounds, we are investigating the thermal decomposition temperature and the solubility in solvents, etc., and paying attention to the fact that the thermal decomposition temperature and the solubility in solvents can be controlled by selecting the joint group that is the binding site, and further research is conducted. Proceeding to using at least one kind 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. In the characteristic heat-sensitive recording material, by applying a certain amount of heat with a heat roll, a thermal head, a hot stamp, or by irradiating light with a laser, a halogen lamp, or the like, methanol, ethanol, etc. The recorded image can be erased by bringing it into contact with an alcohol solvent. Doyare - The - it is possible to re-record it Atere, ie we have found recording medium having a reversible recording property.

Regarding the reversible recording material, a dimerized urea compound in which the joint group is a straight-chain alkylene group having 1 to 12 carbon atoms is preferable in terms of decoloring by heat roll. A recording material containing (for example, compound A-1) as a color developer is exemplified.

A heat-sensitive recording material containing these urea compounds as a color-developing agent is colored by a thermal head or the like, and then 1
The color can be erased by bringing it into contact with a heat roll at 00 ° C to 200 ° C, and this decolorized surface can be printed again with a thermal head or the like. For example, the one using the compound A-1 as the developer showed good results.

The dimerized or trimerized urea compound used in the present invention by itself has a high developing ability as a developing agent in a thermosensitive recording medium, and this compound together with an electron-donating dye precursor is used as a support. The coated surface coated on top shows the basic characteristics that it does not substantially develop color even at 120 ° C, and the background color has excellent solvent resistance. In addition, the urea compounds of the present invention can be added to other compounds depending on the choice of joint group.
Some have a function of heat resistance of the background color of ℃ or more or reversible recording property (coloring / decoloring property). These properties are new properties that have not been known so far, and these urea compounds are excellent materials that have the properties of color developing property and decoloring property even though they are single color developing agents. is there.

The general method for producing the thermosensitive recording medium of the present invention is to disperse (a) a dye precursor and (b) a dimerized urea compound or a trimerized urea compound as a developer. This is a method in which each is dispersed together with a binder, an auxiliary agent such as a filler or a lubricant is added if necessary to prepare a coating liquid, and the coating liquid is applied onto a support by a usual method and dried. In 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 conventionally known in the field of heat-sensitive recording can be used, and although not particularly limited, triphenylmethane leuco dyes, Fluoran-based leuco dyes and fluorene-based leuco dyes are preferred. Hereinafter, typical dye precursors will be exemplified.

3,3-bis (4'-dimethylaminophenyl)
-6-Dimethylaminophthalide (also known as crystal violet lactone (CVL)) 3,3-bis (4'-dimethylaminophenyl) -6-pyrrolidylphthalide 3,3-bis (4'-dimethylamino) Phenyl) phthalide (also known as malachite green lactone (MGL)) tris [4- (dimethylamino) phenyl] methane (also known as leuco crystal violet (LCV)) 3-dimethylamino-6-methyl-7- (m -Trifluoromethylanilino) fluorane 3-diethylamino-6-methyl-fluorane 3-diethylamino-7-methyl-fluorane 3-diethylamino-7-chloro-fluorane 3-diethylamino-6-methyl-7-chlorofluorane 3- Diethylamino-6-methyl-7-anilinofluorane 3-diethylamino-6-methyl-7-p-methylanilinofluorane 3-diethylamino-6-methyl-7- ( o, p-Dimethylanilino) fluorane 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3-diethylamino-6-methyl-7- (o-chloroanilino) fluorane 3-diethylamino-6 -Methyl-7- (p-chloroanilino) fluorane 3-diethylamino-6-methyl-7- (o-fluoroloanilino) fluorane 3-diethylamino-6-methyl-7- (pn-butylanilino)
Fluorane 3-diethylamino-6-methyl-7-n-octylaminofluorane 3-diethylamino-6-chloro-7-anilinofluorane 3-diethylamino-6-ethoxyethyl-7-anilinofluorane 3-diethylamino- Benzo [a] fluorane 3-diethylamino-benzo [c] fluorane 3-diethylamino-6-methyl-7-benzylaminofluorane 3-diethylamino-6-methyl-7-dibenzylaminofluorane 3-diethylamino-7-di (P-Methylbenzyl) aminofluorane 3-diethylamino-6-methyl-7-diphenylmethylaminofluorane 3-diethylamino-7-dinaphthylmethylaminofluorane 10-diethylamino-4-dimethylaminobenzo [a] fluorane 3 -Dibutylamino-6-methyl-fluorane 3-dibutylamino-6-methyl-7-chlorofluorane 3-dibutylamino-6- Methyl-7-anilinofluorane 3-dibutylamino-6-methyl-7-p-methylanilinofluorane 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluorane 3-dibutyl Amino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3-dibutylamino-6-methyl-7- (o-chloroanilino) fluorane 3-dibutylamino-6-methyl-7- (p-chloroanilino ) Fluoran 3-dibuethylamino-6-methyl-7- (o-fluoroloanilino) fluorane 3-dibuethylamino-6-methyl-7- (pn-butylanilino) fluoran 3-dibutylamino-6-methyl- 7-n-octylaminofluorane 3-dibutylamino-6-chloro-7-anilinofluorane 3-dibutylamino-6-ethoxyethyl-7-anilinofluorane 3-din-pentylamino-6-methyl -7- Anilinofluorane 3-di n-pentylamino-6-methyl-7- (o, p-di Methylanilino) fluorane 3-di n-pentylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3-di n-pentylamino-6-methyl-7- (o-chloroanilino) fluorane 3-di n-Pentylamino-6-methyl-7- (p-chloroanilino) fluorane 3-di n-pentylamino-6-methyl-7- (o-fluoroloanilino) fluorane 3-pyrrolidino-6-methyl-7- Anilinofluorane 3-piperidino-6-methyl-7-anilinofluorane 3- (N-methyl-Nn-propylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-Nn- Propylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-iso-propylamino) -6-methyl-7-
Anilinofluorane 3- (N-ethyl-Nn-butylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-iso-butylamino) -6-methyl-7-anilino Fluoran 3- (N-ethyl-Nn-hexylamino) -6-methyl-7-p-
Methylanilinofluorane 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (o,
p-Dimethylanilino) fluorane 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (m-
Trifluoromethylanilino) fluorane 3- (N-ethyl-Nn-hexylamino) -6-methyl-7- (o-
Chloroanilino) fluorane 3- (N-ethyl-N-iso-amylamino) -6-methyl-7-anilinofluorane 3- (N-ethyl-N-iso-amylamino) -6-chloro-7-anilinoflu Oran 3- (N-ethyl-N-3-methylbutylamino) -6-methyl-7
-Anilinofluoran 3- (N-ethyl-Np-toluidino) -6-methyl-7-anilinofluoran 3- (N-ethyl-Np-toluidino) -6-methyl-7- (p-methylanilino) Fluoran 3- (N-ethyl-Np-toluidino) -6-methyl-7- (o, p-dimethylanilino) fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-
Methyl-7-anilinofluorane 3- (N-cyclohexyl-N-methylamino) -6-methyl-7
-Anilinofluorane 3- (N-cyclohexyl-N-methylamino) -7-anilinofluorane 3- (N-ethyl-N-3-methoxypropylamino) -6-methyl-7-anilinofluorane 3- (N-Ethyl-N-3-ethoxypropylamino) -6-methyl-7-anilinofluorane 2- (4-oxahexyl) -3-dimethylamino-6-methyl
-7- Anilinofluorane 2- (4-oxahexyl) -3-diethylamino-6-methyl
-7- Anilinofluorane 2- (4-oxahexyl) -3-dipropylamino-6-methyl-7-anilinofluorane 3- (4``-aminostilbrudil-4'-amino)- 7,8-Benzofuran 3,6,6'- Tris (dimethylamino) spiro [fluorene
-9,3'-phthalide] 3,6,6'-tris (diethylamino) spiro [fluorene
-9,3'-phthalide] 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-diethylamino- 2-Ethoxyphenyl) -3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-diethylamino-2-n-hexylphenyl) -3- (1-
Ethyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylmethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -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) fluorane- γ- (2'-nitro) anilinolactam 3,6-bis (diethylamino) fluorane-γ- (3'-nitro) anilinolactam 3,6-bis (diethylamino) fluorane-γ- (4'-nitro) Anilinolactam 3,6-bis (diethylamino) fluorane-γ-anilinolactam

These dye precursors may be used alone or in admixture of two or more. The fluoran dye precursor has high color-developing properties and stability of the background color, especially in view of the basic function of the heat-sensitive recording material, and is therefore preferably used in the present invention. When importance is attached to thermal stability, naturally, a dye precursor having a high melting point and a high decomposition temperature is preferable. When reversible recording is important, dye precursors such as 3-diethylamino-7- (m-trifluoromethylanilino) fluorane that have weak image stability and a structure that can withstand repeated use and have a high decomposition temperature. Is good.

As the binder which 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, polyacrylic ester,
Polyacrylamide, polyacrylic acid ester, polyvinyl butyral, polystyrol and their copolymers, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, coumarone resin can be exemplified. Alcohol binders are desirable in terms of dispersibility, binder properties, and thermal stability of background color. Further, in the case of reversible recording, a binder with little deterioration that can withstand repeated use is preferable. These binders are used in a state of being dissolved in a solvent such as water, alcohol, ketone, ester, hydrocarbon, or emulsified in water or other medium, or dispersed in a paste form, and used together depending on the required quality. You can also do it.

Further, in the present invention, in the case of producing a heat-sensitive recording material having particularly high thermal stability of the background color, it is generally preferable not to use a sensitizer. This is because when a sensitizer is used, these are melted at a temperature of about the time of drying, and the dye precursor and the developer are reacted with each other, so that the background color tends to develop. However, on the other hand, since the sensitizer enhances the decoloring property, when decoloring property, that is, reversible recording property is more important than thermal stability of the background color, these may be used. As the sensitizer used for that purpose, 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 oxalate di (p-chlorobenzyl).

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

In addition, a release agent such as a fatty acid metal salt, a lubricant such as waxes, a benzophenone-based or benzotriazole-based UV absorber, a waterproofing agent such as glyoxal, a dispersant, an antifoaming agent, etc. should be used. You can also

The compounding amount of the (a) dye precursor of the present invention and the (b) dimerized or trimerized urea compound, and the kinds and compounded amounts of other various components are determined according to the required performance and recording suitability. Although not particularly limited, it is usually 1 to 8 parts of a dimerized or trimerized urea compound and 1 to 20 parts of a filler per 1 part of the dye precursor, and the binder is a total solid content. It is 10 to 25% by weight. When it is used repeatedly like a reversible recording medium, it is desirable that the composition be as simple as possible. These materials are ball mills,
A pulverizer such as an attritor and a sand grinder, or an appropriate emulsifying device is used to atomize the particles to a particle size of several microns or less, and a binder and various additive materials are added to form a coating solution. The target thermosensitive recording medium by applying a coating solution having the above composition to any support such as paper, synthetic paper, non-woven fabric, metal foil, plastic film, plastic sheet, or composite sheet combining these. Is obtained.

Further, an overcoat layer made of a polymer material may be provided on the thermosensitive coloring layer for the purpose of improving the storage stability,
An undercoat layer of a polymeric substance containing a filler may be provided below the heat-sensitive layer for the purpose of increasing the color development sensitivity.

The heat-sensitive recording material of the present invention may be provided with a transparent and strong protective coating by thermally laminating a plastic film by 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, the recording material having a decoloring function is useful as a reversible recording material (rewrite recording material or rewritable recording material) or as a simple display material. However, in the latter case, it is necessary to record and erase at almost the same speed.

There are two methods for erasing the heat-sensitive recording material of the present invention. One method is a method of erasing a recorded image by heat using a heat roll, a thermal head, a hot stamp, a carbon dioxide gas laser, a semiconductor laser, sunlight, a halogen lamp or the like. For example, in the case of hot rolls, the erasing temperature is between 100 ℃ and 200 ℃, and the feed rate is 8 mm
45mm / sec is suitable. Another method is a method of erasing a recorded image by bringing it into contact with an alcohol solvent.

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

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

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

Specific examples of polymethine dyes (cyanine dyes) include, for example, indocyanine green (manufactured by Daiichi Pharmaceutical Co., Ltd.), NK-2014 (manufactured by Japan Photosensitive Dye Research Institute), NK -2612 (manufactured by Japan Photosensitive Dye Research Institute, Inc.), 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. As a squarylium dye, NK-277
2 (manufactured by Japan Photosensitive Dye Research Institute Co., Ltd.) and the like, and as the dithiol complex, toluene dithiol nickel complex, 4-tert-butyl-1,2-benzenedithiol nickel complex, bisdithiobenzyl nickel complex , Bis (4-ethyldithiobenzyl) nickel complex, bis (4-n-propyldithiobenzyl) nickel complex, and the like, and examples of immonium-based dyes or diimmonium-based dyes include
IRG002 (Nippon Kayaku Co., Ltd.), IRG022 (Nippon Kayaku Co., Ltd.)
Manufactured by Yamamoto Chemicals Co., Ltd., and the anthraquinone dye manufactured by IR-750 (Nippon Kayaku Co., Ltd.).
Manufactured) and the like. You may use these light absorbers individually or in mixture of 2 or more types.

These light absorbers are used (a) by simply mixing them in various materials necessary for the recording medium, and (b) JP-A-2-21.
As described in Japanese Patent No. 7287, etc., a method in which a light absorber is melt-mixed in advance in the materials necessary for the recording material and dissolved or dispersed, or (c) various materials required for the recording material. 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 according to the method of use after removing the solvent.
Further, the light absorber may be co-dispersed (simultaneous mixture dispersion) with a color developer and / or a sensitizer, or a dye precursor and / or a sensitizer.

The heat-sensitive recording material of the present invention does not change much in basic performance (for example, ground color stability such as heat resistance and solvent resistance) even if it contains a light absorber. That is, thermal lamination and toner recording are possible even if a light absorber is contained. The same applies to the additional function (reversible recording property). However, when using a sensitizer,
It was recognized that the heat resistance tended to decrease.

[0063]

The novel naphthyl type dimerized urea compound or trimerized urea compound according to the present invention is a color developing agent which is excellent in color development as a basic function and is also excellent in ground color stability against heat and solvent. Among them, there is a color developer having a reversible recording property. The clear reasons for ground color stability and reversible recording properties have not yet been clarified. However, it is estimated as follows.

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

[Chemical 17]

It is considered that an enolization is necessary for the dimerized urea compound or the trimerized urea compound to function as a developer. A high temperature is required for enolization, and the thermal head momentarily reaches a high temperature of 200 to 300 ° C, so the enolization occurs in the urea compound that contacts the thermal head, and the color development function occurs and the dye precursor It is believed that the lactone ring is cleaved to develop color. Therefore, the urea compound does not change until the temperature at which enolization occurs, and the background color remains white because it does not react with the dye precursor, which seems to be the reason for the high heat resistance. Also,
It is considered that the dimerized urea compound or the trimerized urea compound has an increased number of active hydrogens as compared with the monourea compound, so that good color development can be obtained.

On the other hand, if the enol compound thus formed is dissolved for some reason and turned into a keto, it is considered that decolorization may occur, and the decolorization may be brought into contact with an appropriate temperature and heat amount or an alcohol solvent. It is thought that keto-induced phenomenon occurs and the color disappears. Since enolization and ketoization occur under completely different conditions, enolization and ketoization can be repeated under each condition, which will enable reversible recording.

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

[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 medium was manufactured using the following dye precursors as the dye precursor and the compound A-1 as the developer. (See Table 1) (Dye precursor) ODB: 3-N, N-diethylamino-6-methyl-7-anilinofluorane ODB-2: 3-N, N-dibutylamino-6-methyl-7-ani Rinofluorane 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)
That is, first, the developer dispersion (liquid A) and the dye precursor dispersion (solution B) having the following formulations were ground to an average particle diameter of 1 micron with a sand grinder. (Solution A: developer dispersion) Compound A-1 6.0 parts 10% polyvinyl alcohol aqueous solution 18.8 parts Water 11.2 parts (solution B: dye precursor dispersion) 2.0 parts of each of the above dye precursors 10% polyvinyl alcohol aqueous solution 4.6 Part Water 2.6 parts Next, the liquid A (developing agent dispersion), the liquid B (dye precursor dispersion), and the kaolin clay dispersion were mixed at the following ratio to prepare a coating liquid. Solution A: Developer dispersion 36.0 parts Solution B: Dye precursor dispersion 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Coating solution 6.0 g / m ² on one side of 50 g / m ² base paper
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared.

[Examples 6 to 8] In the same manner as in Example 1 except that each of the compounds A-6, A-7 and A-23 was used as a developer, a thermosensitive recording medium was prepared as follows. did. (See Table 1) (Liquid C: Developer Dispersion) Compound A-6, A-7, or A-23 6.0 parts 10% polyvinyl alcohol aqueous solution 18.8 parts water 11.2 parts Then, at the following ratio, liquid C ( The developer dispersion), the ODB dispersion used in Example 1, and the kaolin clay dispersion were mixed to prepare a coating solution. Liquid C: Developer dispersion 36.0 parts ODB dispersion used in Example 1 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Coating solution 6.0 g on one side of 50 g / m ² base paper /
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared.

[Comparative Examples 1 to 7] As described below, thermal recording materials for Comparative Examples were prepared in the same manner as in Examples 1 to 8 using the following known compounds as color 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) Phenylurea (B5) described in JP-A-58-211496, dimerized urea (B6) described in JP-A-5-147357, amidophenol derivative (B7)

[0072]

[Chemical 18]

That is, a dispersion of each of the known developer compounds shown below having the following composition was ground to a mean particle size of 1 micron with a sand grinder. (D liquid: developer dispersion) Known developer compound (B1 to B7) 6.0 parts 10% polyvinyl alcohol aqueous solution 18.8 parts water 11.2 parts Next, at the following ratio, liquid D (developing liquid dispersion), The dispersion liquid of ODB (liquid B) used in Example 1 and the dispersion liquid of kaolin clay were mixed to prepare 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 Coating solution 6.0 g on one side of 50 g / m ² base paper /
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared.

(Evaluation of Thermal Recording Material) The thermal recording material thus obtained was subjected to a recording test by a thermal printer, a thermal stability test for ground color, a thermal laminate test, and an oil ink suitability test.

[Recordability Test (Dynamic Color Density)]: In order to check recording suitability, a word processor (RUPO-90F (manufactured by Toshiba)) was used, and recording was performed on the prepared thermal recording medium with maximum applied energy. The recording section of the Macbeth densitometer (RD-9
14. An amber filter was used. Hereinafter, the concentration measurement was performed under these conditions. ). In this case, the larger the Macbeth value, the higher the recording density and the better the recording suitability.

[Ground color thermal stability test (static color density)]: To check the thermal stability of the ground color of the recording sheet, 1
The prepared heat-sensitive recording material was pressed against the hot plate heated at 20 ° C. and 150 ° C. at a pressure of 10 g / cm ² for 5 seconds, and the recording material was measured with a Macbeth densitometer. In this case, the smaller the Macbeth value is, the less the ground color is colored, and the higher the thermal stability of the ground color is.

[Thermal laminate test (production of laminar recording material)]: Simple laminator (MS Pouch H-140)
The thermosensitive recording material thus obtained was sandwiched between pouch films using Meiko Shokai Co., Ltd. to prepare a laminated thermosensitive recording material, and its ground color part was measured by a Macbeth densitometer. In this case, the smaller the Macbeth value is, the more stable the ground color is. In other words, it is shown that the lamination can be performed without causing the color development. The thermosensitive recording medium using the dimerized or trimerized urea compound of the present invention was capable of laminating while the ground color remained stable.

[Oil-based ink suitability test (ground-color discoloration test with oil-based ink)]: Oil-based red magic ink No. 500
(Manufactured by Teranishi Chemical Co., Ltd.) was used to write on the prepared thermosensitive recording medium, and the degree of discoloration with respect to the original red color was visually measured. ◎ ... No discoloration ○ ... Almost no discoloration △ ... Slightly discolored × ... Remarkably discolored

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. The results are shown in Table 1.

[0080]

[Table 1]

Next, a reversible recording property test was also conducted on the obtained thermosensitive recording medium. [Reversible recording property test]: As in the recording property test, the obtained thermal recording medium was recorded by a word processor, and the recorded thermal recording medium was rotated at a speed of 30 mm at a temperature of 180 ° C.
The recording part and the background color part were measured with a Macbeth densitometer. In this case, it is shown that the smaller the Macbeth density of the recording portion, the higher the decoloring property. After that, the recording was performed again by 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] In the thermosensitive recording medium of Example 4, the reversibility test by the heat roll was repeated 10 times. The Macbeth densities at the 100th recording and the background color were 0.78 and 0.14.

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

[Embodiment 11] Toner recording was carried out on the heat-sensitive recording material of Embodiment 1 using a copying machine (NP6060 Canon Co., Ltd.). As a result, 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 in the present invention. A heat-sensitive recording material was prepared by using the compound A-1 of Example 1 above and a hot melt of a bisdithiobenzylnickel complex as a light absorber and a sensitizer. That is, first, 94 parts of 4-biphenyl-p-tolyl ether was added to the bidithiobenzyl nickel complex 6
Parts were added, heated to 100 to 150 ° C., melted and mixed, and then pulverized to obtain a light absorber. Then, the light absorbent dispersion having the following composition was ground to an average particle size of 1 micron with a sand grinder. (Liquid E: Light Absorber Dispersion) Light Absorber 4.0 parts 10% Polyvinyl alcohol aqueous solution 10.0 parts Water 6.0 parts Next, the developer dispersion (A) used in Example 1 at the following ratios: The dispersion of ODB used in Example 1 (B
Liquid), liquid E (light absorber dispersion liquid), and kaolin clay
The dispersion liquid of was mixed to obtain a coating liquid. 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 50 g / m Coating amount 6.0g / on one side of base paper ²
It is coated and dried so that it has a surface area of m ² , and this sheet is treated with a super calendar so that the smoothness is 500 to 600 seconds.
A thermosensitive recording medium was prepared. For this thermal recording material,
Laser light irradiation was performed using the laser plotter device described in JP-A-3-239598, and the recording portion was measured with a Macbeth densitometer. As the light irradiation conditions, a semiconductor laser LT015M with an oscillation wavelength of 830 nm and an output of 30 mW was used as a recording light source.
An aspherical plastic lens with a numerical aperture of 0.45 and a focal length of 4.5 mm using D (Sharp Co., Ltd.) as a light collecting lens.
Recording speed of 50mm / s using AP4545 (Konica Corp.)
ec, recording interval was 50 microns, and solid recording of 1 cm in length and width was obtained. The Macbeth density in the recording area was 1.09.

[0088]

As described above, the naphthyl-based dimerized urea compound or trimerized urea compound of the present invention does not substantially change the ground color at the ambient temperature of 120 to 150 ° C. Nevertheless, it can be seen that the developer is an epoch-making developer that can obtain a practical image density record by using 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 having excellent storage stability such as heat resistance and solvent resistance as compared with 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) It is possible to easily heat-laminate the thermosensitive recording medium by using a simple laminator or the like. Cards can be easily made. (5) Toner recording can be carried out on the thermosensitive recording medium because the ground color is stable even after passing through a heat roll.

Regarding the thermosensitive recording medium having the erasing function, (6) a new recording system capable of repeating recording / erasing with a color tone is possible and can be used many times, which saves resources. (7) Some of them can be erased only by passing them through a heat roll, and no strict temperature control is required at the time of erasing. (8) Unlike liquid crystals, it can be used as a simple display for recording / erasing using different thermal energy.

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

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

Claims (6)

[Claims] 1. A thermosensitive recording medium having a thermosensitive color developing layer comprising a colorless or light-colored dye precursor and a developer which reacts when heated to develop the color of the dye precursor, wherein the developer has the following general formula: A heat-sensitive recording material which is a urea compound represented by (1), (2) or (3), wherein the heat-sensitive color forming layer contains at least one kind of the urea compound. [Chemical 1] (Here, X represents an alkyl group having 1 to 6 carbon atoms, a halogen atom, or a hydrogen atom. Y is a divalent group having 30 or less carbon atoms, and Z is a divalent group. Represents a trivalent group consisting of 30 or less.) 2. The heat-sensitive recording material 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 the heat-sensitive recording material according to claim 1 or 2 with a plastic film. 4. A transfer sheet for electrophotography, which uses the heat-sensitive recording material according to claim 1 or 2. 5. A reversible recording method comprising: recording on the thermosensitive recording medium according to claim 1 or claim 2, applying heat to a recording section to erase the recorded image, and recording again by thermal recording. 6. The heat-sensitive recording material according to claim 1 or 2, after recording, the recording portion is brought into contact with an alcohol solvent to erase the recorded image, and the heat-sensitive recording is performed again. Reversible recording method.