JP3336593B2 - 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 prepared by grinding and dispersing a colorless or light-colored electron-donating colorless dye and a developer 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.
The color is formed by an instantaneous chemical reaction caused by heating such as a mulled head, a hot stamp, a laser beam, etc. 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, recording apparatuses for heat-sensitive recording media have been diversified and their performance has been improved, and as a result, the quality required for heat-sensitive recording media has also 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 heat energy. On the other hand, from the viewpoint of the storage stability of the recording medium, heat resistance, light resistance, oil resistance, It is required to have excellent water resistance and solvent resistance.

[0004] More recently, with the widespread use of recording methods on plain paper such as the electrophotographic method and the ink jet method, there has been an increasing number of opportunities for comparing thermal recording with those on plain paper. Non-recording part (ground color part)
(Hereinafter referred to as ground color stability) is required to approach the quality of plain paper recording, and in particular, ground color stability to heat or a solvent is required.

Regarding the ground color stability of a thermal recording medium, for example,
JP-A-4-353490 discloses a heat-sensitive recording medium having relatively good ground color stability even under a high temperature condition of about 90 ° C. This heat-sensitive recording material is 4-hydroxydiphenyl.
Contains metal sulfonate compounds and phosphates
A thermosensitive recording medium characterized by the following.

On the other hand, the rapid increase in the consumption of recording media accompanying the spread of OA equipment such as computers, 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 been attracting attention.

As a reversible recording medium, for example, Japanese Patent Application Laid-Open
230993, JP-A-4-366682 and the like, a recording medium utilizing the reversible change of the recording material to a transparent state and a cloudy state by a given temperature, a recording medium utilizing the reversibility of the thermochromic material, leuco A recording medium using a reversible color tone change of a dye 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.
The temperature, for example, at 120 ° C, is still insufficient
Minutes.

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) The clouding (decoloring) speed is slow, and (3)
There are drawbacks such as the need for control. Also,
The white turbid recording medium has no problem when used as a transparent recording medium such as OHP because it provides a contrast between opacity and transparency. For example, facsimile paper,
When used as opaque recording media such as professional paper
Is Put another way, as in the conventional heat-sensitive recording material, when the recording material is applied to the opaque support of white, transparent
It is necessary to provide a colored layer under a layer that reversibly changes to a cloudy state (reversible change layer) . Therefore, the reversible change layer
So, to give the contrast, that is, the color of the colored layer
A thin layer is desirable to make the (base color) clear,
On the other hand, a thick layer is preferable to make the recording medium look white.
In addition, strict control of the thickness of the coating layer is required. On the other hand, in a reversible recording medium using a thermochromic material,
Many thermochromic materials have poor memory properties,
There are problems such as the necessity of continuous heat supply to maintain the colored state. On the other hand, leuco dyes can be used as a coloring source.
Japanese Patent Application Laid-Open No. 60-193691 discloses a reverse recording medium.
Japanese Unexamined Patent Publication No. 60-257289 discloses a reversible recording medium.
I have. The recordings of these publications use the decoloring operation with water or
Is performed with water vapor, and has a practical problem. Japanese Patent Application Laid-Open Nos. 2-188293 and 2-188294 disclose, in a simple layer structure, development (coloring) and color reduction that give a reversible color change to a leuco dye only by controlling heat energy. A material (developing agent) having both functions is disclosed. However, this color-depleting agent has already been erased during the color development process.
Since the action contributes, there is a problem that the color density (recording density) is low.

Accordingly, the present invention provides a thermosensitive recording medium having excellent ground color stability against heat and a solvent, and a thermosensitive recording medium having reversible recording properties capable of recording, erasing, and re-recording. That was the task.

[0011]

The above object has been attained by using a specific urea compound as a developer.

The present invention relates to 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. The present invention relates to a heat-sensitive recording material, characterized by containing a urea compound represented as a color developer in a heat-sensitive coloring layer.

[0013]

Embedded image (Where X is an alkyl group having 1 to 12 carbon atoms, 1 carbon atom
Represents an alkoxy group, a trifluoromethyl group, a nitro group, a halogen atom, or a hydrogen atom. Y represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. N represents an integer of 1 to 3. )

The urea compound represented by the general formula (1)
For example, it can be synthesized by a reaction between a hydrazide compound and an isocyanate compound.

Embedded image RN = C−O + R′-SO ₂ —NH—NH ₂ → R—NH—C (＝ O) —NH—NH—SO ₂ —R ′

Examples of the hydrazide compound include benzenesulfonyl hydrazide and p-toluenesulfonyl hydrazide. On the other hand, as the isocyanate compound,
Phenyl isocyanate, p-bromophenyl isocyanate, o-chlorophenyl isocyanate, m-chlorophenyl isocyanate, p-chlorophenyl isocyanate, 2,5-dichlorophenyl isocyanate, 3,4-dichlorophenyl isocyanate, 2,6 isocyanate -Dichlorophenyl, o-fluorophenyl isocyanate, m-fluorophenyl isocyanate, p-fluorophenyl isocyanate, o-tolyl isocyanate, m-tolyl isocyanate, p-isocyanate
Tolyl, 2,5-dimethylphenyl isocyanate, 3,4-dimethylphenyl isocyanate, 2,6-dimethylphenyl isocyanate, 3,4,5-trimethylphenyl isocyanate, 2-methoxyphenyl isocyanate, isocyanic acid 3 -Methoxyphenyl, 4-methoxyphenyl isocyanate, o-trifluoromethylphenyl isocyanate, m-isocyanate
Trifluoromethylphenyl, p-trifluoromethylphenyl isocyanate, nitrophenyl isocyanate and the like can be mentioned, and any combination can be selected from both.

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

[0017]

Embedded image

Embedded image

The structure of the urea compound represented by the general formula (1) should be appropriately selected depending on the melting point, decomposition temperature, solubility in a solvent, and the like of the urea compound. Absent.

Patents using a phenyl urea compound as a heat-sensitive recording material are disclosed in JP-A-58-211496 and JP-A-59-1811.
Nos. 4694 and 61-211085 disclose patents using an arylsulfone urea compound as a heat-sensitive recording material, for example, in Japanese Patent Application Laid- Open Nos . 5-1311752 and 5-147357. I have. However, these ures
A) Compounds can withstand ground color under high temperature conditions of 120 ° C or higher
Thermal properties were insufficient.

A heat-sensitive recording material using the urea compound represented by the general formula (1) of the present invention as a developer has excellent ground color stability against heat and solvents. That is, this thermal recording medium develops a dark color when high energy is instantaneously applied from a thermal head, which is usually at 200 to 300 ° C., but this recording medium is placed in a high temperature environment of 120 to 150 ° C. However, the recording surface does not substantially develop color, and there is almost no change in ground color.

The heat-sensitive recording material of the present invention has high ground color heat resistance.
For example, (a) add the recording surface after thermal recording
Perform thermal lamination by heat bonding with tic film, etc.
And (b) a thermosensitive recording sheet used as a transfer sheet for electrophotography.
Heat-fixing by attaching toner to the recording layer surface, or
(C) Toner adheres to the heat-sensitive recording surface of the heat-sensitive recorded sheet
It is also possible to fix by heat.

Further, as an advantage of the heat-sensitive recording medium of the present invention, the control of the manufacturing process becomes extremely easy. That is, 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 such that the temperature does not become high even in part so that the base surface of the coated surface does not develop color. Therefore, there was a limit to high-speed coating.
However, the heat-sensitive recording material of the present invention does not develop a ground color even when exposed to hot air at 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.

Further, in the heat-sensitive recording material of the present invention, discoloration due to oil-based ink does not occur , probably because the urea compound used has low solubility in an organic solvent . Therefore, feeling
Writing with oil-based ink on the surface of thermal recording layer of thermal recording medium
Is also possible.

Further, the thermal recording medium of the present invention comprises a heat roll,
Thermal head, hot stamp, carbon dioxide laser,
The recorded image can also be erased by giving an appropriate amount of heat using a semiconductor laser, sunlight, a halogen lamp, or the like. For a hot roll, the decolorization temperature is 100 ~
The feed rate between 200 ° C and 8 mm to 45 mm / sec is appropriate.
If a thermal head or a laser is again applied to the surface from which the image has been erased in this manner, it is possible to perform recording again. That is, the thermosensitive recording medium of the present invention is a reversible recording thermosensitive recording medium.

As a good thing in decoloring by a heat roll, for example, a compound A-1 or the like is used as a color developer.
Thermal recording media are exemplified.

The urea compound used in the present invention by itself has a high color developing property (color developing property) as a color developer in a thermosensitive recording medium. On the other hand, the sensitivity using these compounds
Thermal recording body is not 120 ° C. but substantially colored, "background heat
In addition, depending on the selection of the compound, it is an excellent material that has heat resistance of ground color above 150 ° C or reversible recording (coloring / decoloring). is there.

The general method for producing the thermosensitive recording medium of the present invention comprises dispersing (a) a dye precursor and (b) a urea compound represented by the general formula (1) 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 then coated and dried on a support by an ordinary method.

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. And fluorene-based compounds are preferred, and representative examples thereof are shown below.

<Triphenylmethane Leuco Dye> Crystal Violet Lactone (CVL) Malachite Green Lactone (MGL)

<Fluoran Leuco Dye> 3-Diethylamino-6-methyl-7-anilinofluoran 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- (o-fluoroanilino)
Fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-fluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-ethoxyethyl-7-anilino Fluoran 3-diethylamino-benzo [a] -fluoran 3-pyrrolidino-6-methyl-7-anilinofluoran 3-piperidino-6-methyl-7-anilinofluoran 3-dibutylamino-6-methyl-7 -Anilinofluoran 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-dibutyl Amino-6-methyl-7- (o-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (o-fluoroanilino)
Fluoran 3-dibutylamino-6-methyl-7-chlorofluoran 3-dibutylamino-6-methyl-fluoran 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-dimethylanilino) 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- (o-fluoroanilino) fluoran 3- (N-ethyl-Np-toluidino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6 -Methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilinofluoran 3- (N-ethyl -N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-hexylamino) -6-methyl-7- (p-chloroanilino) fluoran 3- (N-ethyl -N-hexylamino) -6-methyl-7- (m-trifluoromethylanilino) fluoran 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-
Anilinofluoran 3- (N-cyclohexyl-N-methylamino) -7-anilinofluoran 3-cyclohexylamino-6-chlorofluoran 3- (N-methyl-N-propylamino) -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

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

These dye precursors may be used alone or in combination of two or more. The fluoran-based dye precursor is particularly suitable in terms of the coloring property of the heat-sensitive recording material and the stability of the ground color.
It can be preferably used in the present invention. 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 which can be used in the heat-sensitive recording material of the present invention, completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl Polyvinyl alcohol such as alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, and other modified polyvinyl alcohol
Calls: hydroxyethylcellulose, methylcellulo
Carboxymethylcellulose, ethyl cellulose
, Cellulose derivatives such as acetylcellulose;
Tylene-maleic anhydride copolymer, styrene-butadiene
Copolymer, polyvinyl chloride, polyvinyl acetate, polyamide
Cryamide, polyacrylate, polyacryl
Acid esters, polyvinyl butyral, polystyrene,
Of copolymers and their combinations
Polymers ; polyamide resin, silicone resin, petroleum resin,
Resins such as terpene resin, ketone resin, and coumarone resin can be exemplified. Among these examples, the polyvinyl alcohol-based binder has dispersibility, binder properties,
This is desirable from the viewpoint of thermal stability of the ground color. 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. It is also possible.

In the present invention, in particular, when a thermosensitive recording medium having a high ground color thermal stability is manufactured, it is generally better not to use a sensitizer. When a sensitizer is used, these are melted at about the temperature at the time of drying, and the dye precursor and the developer tend to react with each other, so that the ground color tends to develop. However, on the other hand, the sensitizer enhances the decoloring property, so if the decoloring property, that is, the reversible recording property is more important than the thermal stability of the ground color,
These are sometimes used. Sensitizers used for that purpose include 2-di (3-methylphenoxy) ethane, di (p-methylbenzyl) oxalate, p-benzylbiphenyl,
β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, dibenzyl oxalate, and di (p-chlorobenzyl) oxalate are exemplified as preferable ones. it can.

The filler used in the present invention may be an inorganic filler such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, aluminum hydroxide, or a polystyrene-based organic filler, styrene /
Butadiene-based organic fillers, styrene / acrylic-based organic fillers, hollow-based 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 triazole-based ultraviolet absorber, a water-proofing agent such as glyoxal, a dispersant, and an antifoaming agent may be used. it can.

The amount of (a) the dye precursor of the present invention and (b) the urea compound represented by the general formula (1), and the types and amounts of other various components are determined according to the required performance and recording. Although it is determined according to suitability and is not particularly limited, usually, the urea compound 1 is added to one part of the dye precursor.
８8 parts, fillers 1-20 parts, binder is 10-25% by weight of total solids. When used repeatedly, such as in a reversible recording medium, it is desirable that the composition be as simple as possible. These materials are pulverized by a pulverizer such as a ball mill, attritor, sand grinder, or an appropriate emulsifier to a particle size of several microns or less,
A coating liquid is prepared by adding a binder and various additives depending on the purpose. A coating liquid having the above composition is applied to paper, synthetic paper, nonwoven fabric, metal foil, plastic film, plastic sheet.
The desired thermosensitive recording medium can be obtained by applying the composition to an arbitrary support such as a sheet or a composite sheet obtained by combining these.

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

Further, in the heat-sensitive recording medium of the present invention, a transparent and strong protective coating may be provided 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.

In the heat-sensitive recording medium of the present invention , the recorded image is
The erasable thermosensitive recording medium is useful as a reversible recording medium (a rewritable recording medium or a rewritable recording medium). In recent years, liquid crystal displays (liquid crystal displays)
B) is an information display (medium for temporarily displaying information)
The thermosensitive recording medium of the present invention is also used as
Very simple information display using its reversible recording
It can also be used as a body. However, in the latter case
Recording and erasing at almost the same speed.
You.

The heat-sensitive recording material of the present invention may be made into an optical recording material by incorporating a light absorbing agent which absorbs light and converts it into heat in the heat-sensitive recording layer. Examples of the light absorber include immonium such as IRG002 (manufactured by Nippon Kayaku Co., Ltd.) and IRG022 (manufactured by Nippon Kayaku Co., Ltd.), diimmonium compound, bisdithiobenzylnickel complex, toluenedithio-nickel complex, Dithiolate-based nickel complexes such as tert-butyl-1,2-benzenedithiol-nickel complex, indocyanine lean (manufactured by Daiichi Pharmaceutical Co., Ltd.), NK-2014 (manufactured by Japan Photographic Dye Laboratories, Inc.) ), NK-2612 (manufactured by Japan Photographic Dye Laboratories, Inc.), 1,1,5,5-tetrakis (p-dimethylaminophenyl) -3-methoxy-1,4-pentadienetoluene,
Cyanine-based dyes such as 1,5,5-tetrakis (p-diethylaminophenyl) -3-methoxy-1,4-pentadienetoluene, squalium-based dyes such as NK-2772 (manufactured by Japan Photographic Dye Laboratory), Examples include naphthoquinone dyes, phthalocyanine dyes, naphthalocyanine dyes, and anthraquinone dyes. These light absorbers may be used alone or in combination.

[0042]

The urea compound represented by the general formula (1) of the present invention is a color developer having excellent coloring properties and excellent ground color stability against heat and solvents. Also, among them, there are color developers having excellent reversible recording properties. The specific reasons for ground color stability, reversible recording properties, etc., have not yet been elucidated. However, it is estimated as follows.

The structure of the urea compound of the present invention changes as follows according to the conditions. Since this change is a phenomenon similar to keto / enol tautomerism, for the sake of convenience here, ketoization,
This is called enolization.

Embedded image

It is considered that enolization is necessary for the urea compound to function as a color developer. High temperature is required for enolization, and the thermal head
It is thought that since the temperature rises to about 300 ° C., the urea compound which comes into contact with the thermal head undergoes enolization and develops a color developing function to cleave the lactone ring of the dye precursor to form a 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. On the other hand, if the enol compound thus formed is eliminated and ketoized for some reason, it is considered that discoloration may occur, and by contacting with an appropriate temperature and calorie, or 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.

[0045]

【Example】

<Synthesis of Urea Compound> [Synthesis Example 1] Benzenesulfonyl hydrazide (12.0 g, 70
mM) was dissolved in ethyl acetate (300 ml). In this solution,
Phenyl isocyanate (8.1 ml, 75 mM) was added to ethyl acetate (50 m
The solution dissolved in l) was added dropwise. The reaction solution was treated at room temperature for 5 hours, diluted with ethyl acetate, washed with 1N-hydrochloric acid and saturated saline, dehydrated with sodium sulfate, concentrated, and crystallized from n-hexane to obtain a urea compound.

Synthesis Example 2 p-Toluenesulfonyl hydrazide (13.0 g, 70 mM) was dissolved in ethyl acetate (300 ml). To this solution, phenyl isocyanate (8.1 ml, 75 mM)
Was dissolved in ethyl acetate (50 ml) and added dropwise. The reaction solution was treated at room temperature for 4 hours, diluted with ethyl acetate, washed with 1N-hydrochloric acid and saturated saline, dehydrated with sodium sulfate, then concentrated, and crystallized from n-hexane to obtain a urea compound.

<Manufacture of Thermosensitive Recording Material> In the following description, parts and% indicate parts by weight and% by weight, respectively.

[Examples 1 and 2] As shown below, 3-N, N-diethylamino-6-methyl-7-anilinofluoran (ODB) was used as a dye precursor, A thermosensitive recording medium was manufactured using the urea compound represented by (1). That is, a developer dispersion (solution A) and a dye dispersion (solution B) having the following composition were ground by a sand grinder to an average particle diameter of 1 micron. (Solution A: developer dispersion) 6.0 parts of the urea compound of the present invention 10% aqueous solution of polyvinyl alcohol 18.8 parts Water 11.2 parts (Solution B: dye dispersion) 3-N, N-diethylamino-6-methyl-7-ani Linofluorane (ODB) 2.0 parts 10% aqueous solution of polyvinyl alcohol 4.6 parts Water 2.6 parts Then, the following liquids were mixed with a liquid A, a liquid B, and a dispersion of kaolin clay to prepare a coating liquid. Liquid A: developer dispersion liquid 36.0 parts Liquid B: dye 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 3 to 6 As described below, heat-sensitive recording materials were prepared using the following dye precursors as dye precursors. (Dye precursor) CVL: 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide ODB-2: 3-N, N-di-n-butylamino-6-methyl-7-anilino Fluoran I-red: 3,3-bis (1-ethyl-2-methylindole-3-a
Le) phthalide NEW-Blue: 3-N- (4-diethylamino-2-ethoxyphenyl) -3-N- (1-ethyl-2-methylindol-3-yl)-
4-Azaphthalide (C solution: Dye precursor dispersion) 2.0 parts of the above dye precursor 4.6 parts of a 10% aqueous polyvinyl alcohol solution 4.6 parts of water 2.6 parts Then, at the following ratios, A solution (a color developer dispersion), C solution,
And a dispersion liquid of kaolin clay to obtain a coating liquid. Developer dispersion of Example 1 using compound A-1 36.0 parts Liquid C: dye precursor dispersion 9.2 parts Kaolin clay (50% dispersion) 12.0 parts The above coating solution was applied to a base paper of 50 g / m ² . Application amount on one side 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.

[Comparative Examples 1 to 5] As described below, the following compounds were used as color developers to prepare thermosensitive recording media for Comparative Examples. (Known developer compound) Bisphenol A (B-1) Bisphenol S (B-2) 4-hydroxy-4'-iso-propoxydiphenyl sulfone (B-3) Phenylurea (B-4) Bisurea compound (B-5) described in JP-A-58-211496 JP-A-5-147357

[0051]

Embedded image

That is, a dispersion of each of the above developer compounds having the following composition was ground by a sand grinder to an average particle diameter of 1 μm. (D solution: developer dispersion liquid) The above-mentioned developer compound (B-1 to B-5) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Then, at the following ratio, D solution, B solution, And a dispersion liquid of kaolin clay to obtain a coating liquid. Liquid D: developer dispersion 36.0 parts Liquid B: ODB dye dispersion used in Examples 1-2 9.2 parts Kaolin clay (50% dispersion) 12.0 parts The above coating solution was applied to a base paper of 50 g / m ² . Application amount on one side 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 for a comparative example was produced.

The obtained thermosensitive recording medium was subjected to a recording test, a thermal stability test of a ground color, an oil-based ink suitability test, a thermal lamination test and a reversible recording test using a thermal printer as described below.

[Recording Test (Dynamic Color Density)]: A word processor (RUPO90)
F (manufactured by Toshiba Corp.), recording was performed on the thermosensitive recording medium at the maximum applied energy, and the recorded portion was measured using a Macbeth densitometer (RD-914, amber filter). Performed). 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 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 smaller the degree of coloring of the ground color and the higher the thermal stability of the ground color.

[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

[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 urea compound of the present invention could be laminated while the ground color was stable.

[Reversible recording test]: The obtained heat-sensitive recording medium was recorded with a word processor in the same manner as in the recording test, and the recorded heat-sensitive recording medium was heated at 180 ° C. between heat rolls. The paper was passed at a speed of 30 mm / sec, and 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.

Tables 1 and 2 show the evaluation results of Examples 1 to 6 and Comparative Examples 1 to 5.

[0060]

[Table 1]

[Table 2]

Example 7 In the thermal recording medium of Example 1, after recording with a word printer, the recording surface was wiped off with ethanol and the Macbeth density of the recording portion was measured.
It was 0.33.

[Example 8] Toner recording was performed with a copy machine (manufactured by NP6060 Canon Inc.) using the heat-sensitive recording material obtained in Example 1 as a transfer paper. As it was, a clear toner image could be obtained.

Example 9 A dispersion (solution E) of a light-absorbing developer having the following composition was wet-milled for 1 hour with a sand grinder. (E liquid: light-absorbing developer dispersion) Compound A-1 6.0 parts NK-2014 (manufactured by Japan Photochromic Laboratories Co., Ltd.) 1.0 part 10% aqueous polyvinyl alcohol solution 18.8 parts Water 10.2 parts Then, the following ratios Then, the dispersion liquid of the E liquid, the B liquid, and the kaolin clay was mixed to obtain a coating liquid. Solution E: light-absorbing developer dispersion 36.0 parts Solution B: ODB dye dispersion used in Examples 1-2 9.2 parts Kaolin clay (50% dispersion) 12.0 parts 50 g / m ² of the above coating solution 6.0g / applied amount on one side of base paper
coating and drying so as to m ^2, was treated as smoothness of the sheet supercalendered is 500-600 seconds,
An optical recording medium was produced. When this recording medium was irradiated with laser light using a laser plotter apparatus described in JP-A-3-239598, clear printing could be obtained.

[0064]

As described above, the urea compound of the present invention has a practically sufficient image density in a thermal head even though the ground color does not substantially change at an environmental temperature in the range of 120 to 150 ° C. It can be seen that this is an epoch-making developer capable of obtaining the record of Therefore, the following points can be mentioned as effects of the present invention.

(1) Using the urea compound of the present invention as a developer
By using this, the background color can be
Thermal stability with excellent stability (ground color heat resistance, ground color solvent resistance, etc.)
A recording is obtained. (2) The obtained thermal recording medium is used in a conventional thermal recording medium.
Severe conditions that could not be used (for example,
Range of temperature conditions). (3) The obtained thermosensitive recording medium is printed on the recording surface of the thermosensitive recording medium.
It is possible to write freely with oil-based ink. (4) The obtained heat-sensitive recording material is a simple laminating device or the like.
Enables easy thermal lamination of thermal recording media
It is easy to make a card etc.
You. The heat-sensitive recording medium that has been laminated is added by light.
It is possible to record. (5) The obtained thermal recording medium has high ground color heat resistance.
Therefore, toner recording can be performed on the thermosensitive recording medium. (6) The obtained reversible thermosensitive recording medium has a color tone
A new recording system that can repeatedly erase data
It is possible. (7) The obtained reversible thermosensitive recording medium can be used repeatedly.
And help save resources. (8) The obtained reversible thermosensitive recording medium passes through a heat roll.
Can be erased just by letting
No temperature control is required. (9) The obtained reversible thermosensitive recording medium is a liquid crystal display
Unlike a simple display using heat energy
Can be used.

──────────────────────────────────────────────────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-6-328838 (JP, A) JP-A-63-203381 (JP, A) JP-A-54-154526 (JP, A) JP-A-52-127969 (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-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-5-229253 (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

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, represented by the general formula (1). A thermosensitive recording medium comprising a thermosensitive coloring layer containing a urea compound as a color developer. Embedded image (Where X is an alkyl group having 1 to 12 carbon atoms, 1 carbon atom
Represents an alkoxy group, a trifluoromethyl group, a nitro group, a halogen atom, or a hydrogen atom. Y represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. N represents an integer of 1 to 3. ) 2. A thermosensitive recording card obtained by laminating the thermosensitive recording medium according to claim 1 with a plastic film. 3. An electrophotographic transfer sheet using the heat-sensitive recording medium according to claim 1. 4. An optical recording medium according to claim 1, wherein the recording layer of the thermosensitive recording medium contains a light absorbing agent that absorbs light and converts it into heat. 5. A reversible recording method, wherein after recording on the thermal recording medium according to claim 1, heat is applied to a recording section to erase a recorded image, and thermal recording is performed again. 6. A reversible recording method, wherein after recording on the heat-sensitive recording medium according to claim 1, an alcohol-based solvent is brought into contact with the recording portion to erase the recorded image, and then heat-sensitive recording is performed again.