JPH0710624B2 - Multicolor thermal recording material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-sensitive recording material that develops multiple colors.

More specifically, the present invention relates to a multicolor thermosensitive recording material for thermally recording images having a plurality of hues substantially independently.

<< Prior Art >> In the thermal recording method, (1) development is not necessary, (2) when the support is paper, the quality of the paper is close to that of ordinary paper, (3) easy handling, (4) color density It has been rapidly popularized in the field of monochrome facsimiles and printers in recent years because of its advantages such as high cost, (5) simple and inexpensive recording device, and (6) no noise during recording. These thermal recording materials are papers, synthetic papers, and the like coated with a color former and a developer, and are recorded by a heating process using a thermal head based on an electric signal corresponding to the original. .

Even in such a recording field, with the rapid development of the information industry, there is an increasing demand for easily obtaining a color hard copy from a terminal of an information device such as a computer or a facsimile. As this method, an inkjet method and a thermal transfer method have been studied. However, since this ink jet system is a system in which the ink containing the colorant is ejected from a thin nozzle, the colorant and other contents are likely to be clogged in the nozzle, and there is a big defect that the reliability of recording is lacking. Further, the heat-sensitive transfer method is a method in which ink on an ink sheet is heated and melted in an image form and transferred onto paper, so that it is necessary to use four ink sheets in order to obtain a color image of four colors, for example. However, it is uneconomical to use a large amount of ink sheets. Also, in the case of the ink jet system, the user must always make sure that the ink liquid does not run short, and in the case of the thermal transfer system,
It is necessary to take care not to run out of ink sheets. That is, both of these methods require users to perform complicated management.

On the other hand, the thermal recording method does not require the complicated management described above and has high recording reliability. Therefore, if a multicolor recording material is realized by this method, it will be easy to use without the drawbacks of the conventional methods. . However, in order to realize multiple colors, it has been necessary to incorporate a number of color-developing mechanisms corresponding to the number of color-developing colors on the same support and to control and act each color-developing mechanism. However, it was not sufficient in terms of hue and color separation.

For example, as one of the conventional methods, Japanese Patent Publication No. 51-19989,
52-11231, JP-A-54-88135, 55-133991,
As described in JP-A-55-133992, there is a system in which a plurality of color-forming units are simply sequentially added as the applied heat energy increases and the colors are mixed and the hue changes while becoming muddy. Other methods include, for example, Japanese Examined Patent Publications Nos. 50-17868, 51-5791, and 57.
As disclosed in JP-A-14318, JP-A-57-14319, and JP-A-55-161688, when a color-forming unit having a higher thermal response temperature develops color, a decoloring agent acts at the same time to form a color-forming unit which develops color at low temperature Some have incorporated an erasing mechanism called erasing.

<Problems to be Solved by the Invention> However, all of them are not only capable of realizing a small number of hues that can be developed, but also have bleeding due to bleeding and color mixing, and thus are not considered to have sufficient functions as a color hard copy. Hard to say. In particular, as a color hard copy, the fact that the number of coloring hues is small was a fatal drawback in principle. The following points can be given as one of the major reasons why this drawback cannot be overcome in the past. That is,
For example, when trying to increase the number of coloring hues, simply by increasing the number of applied heat energy fractions and widening the energy difference between them, a plurality of corresponding thermosensitive coloring layers can be formed on the same support. It suffices to design individual heat-sensitive recording materials, but in reality, if the applied heat energy is spread to a lower region than before, problems will occur in terms of raw storage stability (so-called fog) of the recording material itself. When the applied heat energy is spread to a high area, serious problems are newly caused in terms of image scorching, poor print running property due to fusion (for example, sticking), and shortening of life of the thermal head. Therefore, conventionally, the number of fractions of the applied heat energy is practically the maximum limit of about two fractions when trying to satisfy the color separation property.

On the other hand, as the support of the thermal recording material, an opaque support such as paper or synthetic paper is usually used. This is because the color image is simply read as a reflection image from one side.

Examples of conventional heat-sensitive recording materials provided on a substantially transparent support include Japanese Patent Publication No. 40-20151, Japanese Patent Application No. 60-68875 and Japanese Patent Application No. 60-184483. This is done for the purpose of obtaining a high-contrast image or a high-quality image excellent in gloss by observing the formed recorded image from the transparent support side. Further, JP-A-57-208298 has been proposed as an example in which a thermosensitive coloring layer is provided on both sides of a support. The purpose of this is to reduce the loss in terms of cost and storage space of printed copies by printing and recording on both sides of the opaque support, and in any case, it relates to the above-mentioned multicolor recording material. It did not make a special contribution to the shortcomings.

Further, an invention of providing a thermosensitive recording layer having different hues on both sides of a transparent support to obtain a two-color or a plurality of color-developed images is disclosed in JP-A-49-114431 and JP-A-50-3640. Kaisho
Proposed in No. 60-4092.

However, since the thermosensitive coloring layer is a dispersion of the coloring component and the developing component in the solid state, the coloring layer itself becomes an opaque layer due to light scattering. It is impossible to obtain a vividly color-fractionated multicolor image. Further, in JP-A-60-4092, there is a description that each component is dissolved and applied to the same layer in order to improve the transparency of the thermosensitive coloring layer. In this case,
Since the color of each component easily occurs before printing,
So-called fog occurs. Therefore, the above-mentioned known techniques have a small number of possible color fractions in any case, and are essentially insufficient as a multicolor recording material.

The present inventors have conducted extensive studies to solve the drawbacks of the related art, and as a result, by providing, on both sides of the transparent support, a hue that is substantially transparent and develops different hues, the heat sensitivity is better than ever before. The inventors have found that a colored image can be obtained and have reached the present invention.

Therefore, it is a first object of the present invention to provide a heat-sensitive recording material which can sufficiently control the number of hues to be formed and color separation and can obtain a substantially multicolor image.

A second object of the present invention is to provide a method for forming a good multicolor image by a thermal recording system.

<< Means for Solving the Problem >> The above-mentioned object of the present invention is a multicolor thermosensitive recording material comprising, on both surfaces of a transparent support, one or more color forming unit layers capable of forming different hues, respectively. At least one of the color forming unit layers is substantially transparent, and the color forming component contained in the transparent color forming unit layer is a combination of a diazonium salt and a coupler, or a combination of a basic dye precursor and a developer. Among the combined color-forming components, the diazo compound or the basic dye precursor is encapsulated in microcapsules, and the coupler or developer coexisting with the microcapsules is a poorly water-soluble or water-insoluble organic compound. This is achieved by a multicolor heat-sensitive recording material characterized by being dissolved in a solvent, emulsified and dispersed, and then coated.

A more desirable embodiment of the multicolor heat-sensitive recording material of the present invention (hereinafter abbreviated as heat-sensitive material) uses a transparent support having a transparent undercoat layer on both surfaces, and further has one or more heat-sensitive layers (that is, the whole) on both surfaces thereof. As a plurality of heat-sensitive layers that develop different hues, and a protective layer.

<< Operation >> A method for easily obtaining a good multicolor image using the heat-sensitive material of the present invention will be described with reference to the drawings.

FIG. 1 shows a heat-sensitive material of the present invention in which a cyan coloring layer and a magenta coloring layer are provided on both sides of a transparent support.

Both heat sensitive layers shall develop color with the same applied heat energy,
If an image is thermally recorded from both sides with a hot pen or a thermal head, cyan and magenta colors can be independently developed on both sides of the support with substantially the same applied energy as shown in FIG. In this case, since the support is substantially transparent, when viewed from one side, cyan, cyan + magenta (blue) and magenta colors can be achieved with good color separation (see FIG. 2).

In the above, the case of two color forming units of cyan and magenta has been described, but the case of using three color forming units of cyan, magenta and yellow is basically the same. That is,
For example, a heat-sensitive layer that develops yellow on one surface of the transparent support,
A magenta coloring layer is provided on the opposite surface, and then a cyan coloring layer is overlaid (see FIG. 3). In this case, in order to independently develop the third color, it is desirable to employ a system of a coupling coloring reaction of a diazo compound and a photofixing reaction as disclosed in JP-A-61-40192. That is, first, the yellow layer and the cyan layer on the outer surfaces of both sides of the support are independently developed by low thermal energy thermal recording. After that, light fixing is performed using a light source of a specific wavelength that selectively photodecomposes only yellow and cyan diazo. Then, by thermally recording the inner magenta layer having lower thermal sensitivity with higher heat energy than the previous time, cyan, magenta, and yellow can be independently developed on both sides of the support. Moreover, the thermal energy used for developing the color of the magenta layer does not impose an excessive burden on the recording material and the apparatus, and is therefore of great significance.
As a result, when viewed from one side of the transparent support, cyan, magenta, yellow, cyan + magenta (blue), magenta + yellow (red), cyan + yellow (green), and cyan, which have been difficult to obtain in conventional thermal recording, are used. A total of 7 basic colors of + magenta + yellow (black) can be realized with good color separation (see FIG. 4). Since the yellow color-developing layer separates the support, all the above-mentioned color reproduction is possible without fixing. Further, those skilled in the art can easily understand that the number of colors that can be realized by color mixing can be synergistically increased by controlling the color development of each unit by appropriately adjusting the applied heat energy. .

As described above, an example of the multicolor coloring process of the present invention is schematically shown.The material used for the thermosensitive recording according to the present invention is a component that causes a coloring reaction due to contact of a substance by heating, and specifically, an acidic component. A combination of a substance and a basic dye precursor, and a combination of a diazo compound and a coupling compound.

The basic dye precursor in the former combination has a property of developing a color by donating electrons or by receiving a proton such as an acid, and is not particularly limited, but is generally colorless. A compound having a partial skeleton such as a lactone, a lactam, a sultone, a spiropyran, an ester, an amide, etc., and the partial skeleton is ring-opened or cleaved upon contact with a color developer is used. Specifically, there are crystal violet lactone, benzoyl leuco methylene blue, malachite green lactone, rhodamine B lactam, 1,3,3-trimethyl-6'-ethyl-8'-butoxyindolinobenzospiropyran and the like.

As a developer for these color formers, an acidic substance such as a phenol compound, an organic acid or a metal salt thereof, an oxybenzoic acid ester is used. The color developer preferably has a melting point of 50 ° C. to 250 ° C., and particularly a water-insoluble phenol or organic acid having a melting point of 60 ° C. to 200 ° C. is preferable.

Specific examples of these color developers are described in, for example, Japanese Patent Application No. 60-132990.

The other diazo compound of the heat-sensitive recording color-forming material according to the present invention is one that develops a desired hue by reacting with a developer called a coupling component described below, and has a specific wavelength before the reaction. The substance decomposes when exposed to the light of, and no longer has a coloring ability even when the coupling component acts. The hue in this coloring system is mainly determined by the diazo dye produced by the reaction of the diazo compound and the coupling component. Therefore, as is well known, the coloring hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupling component, and almost any coloring hue can be obtained depending on the combination. be able to. For this reason, one layer may contain various diazo compounds and one type of coupling component or another additive may be incorporated in the same layer. At this time, each unit coloring group has a different diazo compound. And other common coupling components and other additives. Further, there is a combination in which different coupling components are contained in some layers and the same diazo or other additive is incorporated in each layer. At this time, each unit coloring group is composed of a different coupling component and other common diazo compounds and additives. In any case, each unit coloring group is composed of one or more diazo compounds and one or more coupling components and other additives which are combined so as to have different coloring hues.

The photodecomposable diazo compound in the present invention refers to an aromatic diazonium salt.

It is generally said that the photolysis wavelength of a diazonium salt is its absorption maximum wavelength. It is known that the maximum absorption wavelength of diazonium salt changes from about 200 nm to about 700 nm depending on its chemical structure. ("Photolysis and Chemical Structure of Photosensitive Diazonium Salts" written by Takahiro Tsunoda and Ao Yamaoka, Journal of the Photographic Society of Japan 29 (4) 197-205 (1965)). Decomposes with light of a specific wavelength depending on the structure, and if the chemical structure of the diazonium salt is changed, the same coupling component and the hue of the dye at the time of the coupling reaction are also changed, which is preferably used in the present invention. it can.

The diazonium salt is a compound represented by the general formula ArN ₂ ⁺ X ⁻ . (In the formula, Ar represents a substituted or unsubstituted aromatic moiety, N ₂ ⁺ represents a diazonium group, and X ⁻ represents an acid anion.) In the present invention, diazonium compounds having different photolysis wavelengths are used. Although it is one of the desirable modes to use, 4-diazo-1 is a compound having a photolytic wavelength near 400 nm.
-Dimethylaminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-1-dipropylaminobenzene, 4-diazo-1-methylbenzylaminobenzene, 4-diazo-1-dibenzylaminobenzene, 4-
Diazo-1-ethylhydroxyethylaminobenzene,
4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-dimethylamino-2-methylbenzene, 4-diazo-1-benzoylamino-2,5-diethoxybenzene, 4-diazo-1- Morpholinobenzene, 4-diazo-1-morpholino-2,5-diethoxybenzene, 4-diazo-1-morpholino-2,5-dibutoxybenzene, 4-diazo-1-anilinobenzene, 4-
Diazo-1-toluylmercapto-2,5-diethoxybenzene, 4-diazo-1,4-methoxybenzoylamino-2,5-diethoxybenzene and the like can be mentioned.
Compounds having a photolytic wavelength at 370 nm include 1-diazo-4- (N, N-dioctylcarbamoyl) benzene, 1-diazo-2-octadecyloxybenzene, and 4
-Diazo-4- (4-tert-octylphenoxy) benzene, 1-diazo-4- (2,4-di-tert-amylphenoxy) benzene, 1-diazo-2- (4-tert-octylphenoxy) benzene , 1-diazo-5-chloro-
2- (4-tert-octylphenoxy) benzene, 1-
Diazo-2,5-bis-octadecyloxybenzene, 1
-Diazo-2,4-bis-octadecyloxybenzene,
1-diazo-4- (N-octyltheuroylamino) benzene and the like can be mentioned. The aromatic diazonium compounds represented by the above-mentioned examples can be widely changed in photodecomposition wavelength by arbitrarily changing the substituents.

Specific examples of the acid anion include CnF ₂ n + ₁ COO ⁻ (n is 3 to
Represent _{9), CmF 2 m + 1} SO 3 - (m represents 2-8),
_{(ClF 2 l + 1 SO 2} ) 2 CH - (l represents 1 to 18), PF ₆ ^- etc.

Specific examples of the diazo compound (diazonium salt) include the following examples.

The developer for the diazo compound used in the present invention is a coupling component that forms a dye by coupling with a diazo compound (diazonium salt).

Specific examples thereof include, for example, 2-hydroxy-3-naphthoic acid anilide, resorcin, and Japanese Patent Application No.
The thing described in -287485 can be mentioned.

Further, by using two or more of these coupling components in combination, an image with any color tone can be obtained. Since the coupling reaction between these diazo compounds and the coupling component easily occurs in a basic atmosphere, a basic substance may be added in the layer.

As the basic substance, a poorly water-soluble or water-insoluble basic substance or a substance which generates an alkali upon heating is used. Examples thereof are inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles. , Morpholines,
Examples thereof include nitrogen-containing compounds such as piperidines, amidines, formazines and pyridines. Specific examples of these are described in, for example, Japanese Patent Application No. 60-132990.

Two or more basic substances may be used in combination.

The materials that cause the above-mentioned color development reaction are from the viewpoint of improving the transparency of the heat-sensitive layer, from the viewpoint of raw storability that prevents contact between the color developer and the color developer at room temperature (prevention of fog), and color development with the desired applied heat energy. From the viewpoint of controlling the color development sensitivity as described above, a part of the components is encapsulated and used.

A preferable microcapsule is one that prevents contact between substances inside and outside the capsule at room temperature due to the substance sequestering action of the walls of the microcapsule and increases the permeability of the substance only while being heated to a certain temperature or higher. This phenomenon is a new technique previously found by the present inventors, and the permeation initiation temperature can be freely controlled by appropriately selecting the capsule wall material, the capsule core substance, and the additive material. The permeation initiation temperature in this case corresponds to the glass transition temperature of the capsule wall (eg, JP-A-59-91438, Japanese Patent Application No. 59-190).
No. 886, Japanese Patent Application No. 59-99490, etc.).

In order to control the glass transition point specific to the capsule wall, it is necessary to change the type of capsule wall forming agent. Examples of the wall material of the microcapsule include polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol and the like. . In the present invention, two or more of these polymer substances may be used in combination.

In the present invention, among the above polymeric substances, polyurethane, polyurea, polyamide, polyester, polycarbonate and the like are preferable, and polyurethane and polyurea are particularly preferable.

The microcapsules used in the present invention are preferably microencapsulated by emulsifying a core substance containing a reactive substance such as a color former, and then forming a wall of a polymer substance around the oil droplets. In this case, the reactant forming a polymer substance is added inside the oil droplet and / or outside the oil droplet. Details of the microcapsules that can be preferably used in the present invention, such as the preferred method for producing the microcapsules, are described in, for example, JP-A-59-222716.

Here, as the organic solvent for forming the oil droplets, generally, it can be appropriately selected from high boiling point oil,
In particular, when an organic solvent suitable for dissolving the color developer described below is used, the solubility with respect to the color developing agent is excellent, the color density and the color developing rate at the time of thermal printing are increased, and the fog is also reduced. It is possible because it is possible.

When making a microcapsule, it can be made from an emulsion containing 0.2 wt% or more of the component to be microencapsulated.

The coupling component is 0.1 with respect to 1 part by weight of the diazo compound.
It is preferable to use ˜10 parts by weight and the basic substance in a ratio of 0.1 to 20 parts by weight. On the other hand, with respect to 1 part by weight of the basic dye precursor, 0.3-160 parts by weight of the color developer, preferably 0.3
It is preferable to use -80 parts by weight.

In the present invention, the size of the microcapsules is preferably 2 μm or less, and particularly preferably 1 μm or less in terms of volume average particle size according to the measuring method described in JP-A-60-214990.

The preferred microcapsules manufactured as described above are not destroyed by heat or pressure as used in conventional recording materials, and the reactive substance contained in the core and outside of the microcapsules is the microcapsule wall. Can permeate and react.

In the present invention, it is also possible to use a color forming aid.

The color-forming aid that can be used in the present invention is a substance that increases the color-developing density during heating printing or lowers the minimum color-forming temperature, and is a coupling component, a basic substance, a color-developing agent, a color-developing agent or diazo. It is for the purpose of creating a situation in which the diazo, basic substance, coupling component, color former and developer are likely to react with each other by the action of lowering the melting point of the compound or the like or lowering the softening point of the capsule wall.

Examples of color-forming aids include phenol compounds, alcoholic compounds, amide compounds, sulfonamide compounds, and the like.
Specific examples include p-tert-octylphenol, p-
Benzyloxyphenol, phenyl p-oxybenzoate, benzyl carbanylate, phenethyl carbanylate,
Examples thereof include compounds such as hydroquinone dihydroxyethyl ether, xylylene diol, N-hydroxyethyl-methanesulfonic acid amide, and N-phenyl-methanesulfonic acid amide. These may be contained in the core substance or may be added outside the microcapsules as an emulsified dispersion.

In the present invention, in order to obtain a substantially transparent thermosensitive coloring layer, after dissolving the developer for the basic dye precursor or diazo compound which is a coloring agent in a water-insoluble or insoluble organic solvent, This is mixed with an aqueous phase containing a surfactant and having a water-soluble polymer as a protective colloid and used in the form of an emulsion-dispersed dispersion.

The organic solvent that dissolves the color developer can be appropriately selected from high boiling point oils, and in particular, it is known as a pressure-sensitive oil and has two or more benzene rings and the number of hetero atoms is not more than a specified number. Oils are preferred. Such oils include compounds represented by the following general formulas (I) to (IV) and triallylmethane (eg, tritoluylmethane, toluyldiphenylmethane), terphenyl compounds (eg, terphenyl), alkyl compounds (eg, Terphenyl), alkylated diphenyl ethers (eg propyl diphenyl ether), hydrogenated terphenyls (eg
In addition to hexahydroterphenyl) and diphenyl ether, it is preferable to use a maleic acid ester represented by the general formula (IV) from the viewpoint of emulsion stability of the emulsion dispersion of the color developer.

In the formula, R ¹ represents hydrogen or an alkyl group having 1 to 18 carbon atoms, and R ² represents an alkyl group having 1 to 18 carbon atoms. p ¹ and q ¹ represent an integer of ¹ to 4, and the number of alkyl groups is 4 or less.

The alkyl group of R ¹ and R ² is preferably an alkyl group having 1 to 8 carbon atoms.

In the formula, R ³ is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, R ⁴
Represents an alkyl group having 1 to 12 carbon atoms. n represents 1 or 2.

p ² and q ² represent an integer of 1 to 4. When n = 1, the total number of alkyl groups is 4 or less, and when n = 2, the total number of alkyl groups is 6 or less.

In the formula, R ⁵ and R ⁶ represent a hydrogen atom or the same or different alkyl group having 1 to 18 carbon atoms. m represents an integer of 1 to 13. p ³ and q ³ represent an integer of 1 to 3, and the total sum of alkyl groups is 3 or less.

In addition, the alkyl group of R ⁵ and R ⁶ is particularly preferably an alkyl group having 2 to 4 carbon atoms.

Examples of the compound represented by the formula (I) include dimethylnaphthalene, diethylnaphthalene, diisopropylnaphthalene and the like.

Examples of the compound represented by the formula (II) include dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl and diisobutylbiphenyl.

Examples of the compound represented by the formula (III) include 1-methyl-
1-dimethylphenyl-1-phenylmethane, 1-ethyl-1-dimethylphenyl-1-phenylmethane, 1-
Examples include propyl-1-dimethylphenyl-1-phenylmethane.

In the formula, R is a C _{1 to} C ₁₈ alkyl group, and particularly C _{1 to} C ₅
Alkyl groups of are preferred.

It is also possible to use the above oils in combination, or to use in combination with other oils.

In the present invention, an auxiliary solvent may be added to the above organic solvent as a solvent auxiliary having a low boiling point. As such an auxiliary solvent, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.

The water-soluble polymer to be contained as a protective colloid in the aqueous phase in which the developer is mixed with the dissolved oil phase can be appropriately selected from known anionic polymers, nonionic polymers and amphoteric polymers. However, poe vinyl alcohol, gelatin, cellulose derivatives and the like are preferable.

As the surfactant to be contained in the aqueous phase, it is possible to appropriately select and use anionic or nonionic surfactants that do not cause precipitation or aggregation by acting on the protective colloid. . Preferable surfactants include sodium alkylbenzene sulfonate (for example, sodium lauryl sulfate), dioctyl sodium sulfosuccinate, polyalkylene glycol (for example, polyoxyethylene nonylphenyl ether) and the like.

The emulsified dispersion of the developer in the present invention is a means used for ordinary fine particle emulsification such as high speed stirring and ultrasonic dispersion of an oil phase containing a developer and an aqueous phase containing a protective colloid and a surfactant. Can be easily obtained by mixing and dispersing.

At this time, the oil droplet size (diameter) of the color developer emulsified dispersion is preferably 7 μm or less in order to obtain a transparent heat-sensitive layer having a haze of 40% or less. More preferably, it is within the range of 0.1 to 5 μ.

Also, the value of the ratio of the oil phase to the water phase (oil phase weight / water phase weight)
Is preferably 0.02 to 0.6. More preferably, it is 0.1 to 0.4. If it is less than 0.02, the amount of water phase is too large to be diluted and sufficient color development cannot be obtained, and if it is more than 0.6, the viscosity of the liquid is increased, which causes inconvenience in handling and a decrease in transparency.

The heat-sensitive material of the present invention can be coated using a suitable binder.

As the binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, arabic rubber, gelatin, polyvinyl pyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-vinyl acetate copolymer Various emulsions such as coalescence can be used. The amount used is 0.5 to 5 g / m ² in terms of solid content.

In the present invention, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid and the like can be added as an acid stabilizer in addition to the above materials.

Further, the heat-sensitive material in the present invention can be seen as a transparent image or a reflection image from one side of the transparent support, but especially in the latter case, the image is not clear when the back side of the background is visible. Alternatively, a white pigment may be added to the heat-sensitive layer to make it appear white, or a layer containing a white pigment may be additionally applied. In any case, it is effective to perform the process for the outermost layer on the reflection side of the recorded image. Examples of preferable white pigments include talc, calcium carbonate, calcium sulfate, magnesium carbonate, magnesium hydroxide, alumina, synthetic silica, titanium oxide, barium sulfate, kaolin, calcium silicate, urea resin and the like.

Further, when the outermost color-forming layer itself is made opaque by using a color-forming component other than diazo used in the present invention, a color-developing component, etc., it is preferable to use these by solid-dispersing them with a sand mill or the like. In this case, they are separately dispersed in the water-soluble polymer solution. Preferred water-soluble polymers include water-soluble polymers used when making microcapsules. At this time, the concentration of the water-soluble polymer is 2 to 30% by weight, and the color-forming component other than diazo and the developer are added to the water-soluble polymer solution so as to be 5 to 40% by weight, respectively.

The dispersed particle size is preferably 10 μm or less. Further, the coating amount of thermosensitive layer ^{3g / m 2 ~20g / m 2} , it is preferable that particularly is between ^{5g / m 2 ~15g / m 2} . If it is 3 g / m ² or less, sufficient sensitivity cannot be obtained, and even if it is coated at 20 g / m ² or more, the quality is not improved, which is a cost disadvantage.

The heat-sensitive layer in the present invention needs to be substantially transparent for improving color separation. The term “substantially transparent” as used herein means 40 in terms of haze (%) (measured by integrating sphere method HTR meter manufactured by Nippon Seimitsu Kogyo Co., Ltd.).
Must be less than or equal to%. It is preferably 30% or less, more preferably 20% or less. However, the actual transparency of the heat-sensitive layer test sample is greatly affected by light scattering due to fine irregularities on the surface of the heat-sensitive layer. Therefore, the transparency peculiar to the heat-sensitive layer to be a problem in the present invention, that is, when the transparency inside the heat-sensitive layer is measured with a haze meter, a transparent adhesive tape is attached onto the heat-sensitive layer as a simple method, Evaluation is made with the value measured with scattering almost excluded.

In the present invention, the protective layer which may be provided on the heat-sensitive layer is composed of at least silicon-modified polyvinyl alcohol and colloidal silica.

The silicon-modified polyvinyl alcohol used in the present invention is
It is not particularly limited as long as it contains a silicon atom in the molecule, but usually a silicon atom contained in the molecule is an alkoxyl group, an acyloxyl group or a hydroxyl group obtained by hydrolysis or an alkali metal salt thereof or the like. It is preferable to use those having a reactive substituent.

Details of such a method for producing a modified polyvinyl alcohol containing a silicon atom in its molecule are described in JP-A-58-193189.

The colloidal silica used in the present invention is used as a colloidal solution in which ultrafine particles of silicic acid anhydride are dispersed in water using water as a dispersion medium. The particle size of colloidal silica is
It is preferably 10 m-100 mμ and a specific gravity of 1.1-1.3. In this case, the colloidal solution having a pH value of about 4 to about 10 is preferably used.

When the protective layer is provided on the surface of the heat-sensitive recording material, the surface scattering phenomenon is suppressed as in the case of applying the transparent adhesive tape, and surprisingly, the transparency of the protective layer is extremely good, As a result, the transparency of the entire heat-sensitive material can be improved significantly. Further, when this protective layer is provided as the outermost layer of the recording material, the mechanical strength of the surface of the heat-sensitive layer is improved, and when it is provided as an intermediate layer between the laminated layers, the role of preventing unnecessary color mixing between layers. Can additionally be fulfilled.

A suitable blending ratio of silicon-modified polyvinyl alcohol and colloidal silica in the present invention is 0.5 parts by weight of colloidal silica to 1 part by weight of silicon-modified polyvinyl alcohol.
To 3 parts by weight, more preferably 1 to 2 parts by weight. If the amount of colloidal silica used is less than 0.5 parts by weight, the effect of improving transparency is small, and if it is used in an amount of 3 parts by weight or more, the film of the protective layer is cracked and the transparency is rather lowered.

You may use together a 1 or more types of polymer for a protective layer. Specific examples of polymers that can be used in combination include methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, starches, gelatin, acacia, casein, styrene-maleic anhydride copolymer hydrolyzate,
Styrene-maleic anhydride copolymer half ester hydrolyzate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide derivative, polyvinylpyrrolidone, sodium polystyrenesulfonate, sodium alginate, and other water-soluble polymers and styrene-butadiene rubber latex, acrylonitrile -Bradiene rubber latex, methyl acrylate-butadiene rubber latex, water-insoluble polymers such as polyvinyl acetate emulsion, and the like. The amount to be used in combination is 0.01 to 0.5 with respect to 1 part by weight of silicon-modified polyvinyl alcohol.
Parts by weight are preferred.

Pigments, metal soaps, waxes, cross-linking agents and the like are added to the protective layer for the purpose of improving matching with a thermal head during thermal printing and improving water resistance of the protective layer.

Pigments include zinc oxide, calcium carbonate, barium sulphate, titanium oxide, lithopone, talc, rouxite, kaolin, aluminum hydroxide, amorphous silica, etc., and their addition amount is 0.05 to 2 times the total weight of the polymer, Particularly preferably 0.1
~ 0.5 times the amount. When the amount is 0.05 times or less, it is ineffective for improving the matching property with the head, and when the amount is 2 times or more, the transparency and sensitivity of the heat-sensitive recording material are remarkably lowered and the commercial value thereof is impaired.

Metal soaps include emulsions of higher fatty acid metal salts such as zinc stearate, calcium stearate and aluminum stearate, and are added in an amount of 0.5 to 20% by weight, preferably 1 to 10% by weight based on the total weight of the protective layer. To be done.
Examples of the wax include paraffin wax, microcrystalline wax, carnauba wax, methyl roll stearamide, polyethylene wax, and emulsion of silicone, which are 0.5 to 40% by weight, preferably 1 to 20% by weight of the total weight of the protective layer. Added in quantity.

Further, in order to uniformly form a protective layer on the heat sensitive layer, a surfactant is added to the protective layer forming coating liquid. Surfactants include sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, and the like, and specifically, sodium salts of di- (2-ethylhexyl) sulfosuccinic acid, di- (n-hexyl) sulfosuccinic acid, or the like. There are ammonium salts and the like.

Further, in the protective layer, a surfactant, a polymer electrolyte or the like for preventing the heat-sensitive recording material from being charged may be added. The solid coating amount of the protective layer is usually preferably 0.2-5 g / m ^2, more preferably from 1g~3g / m ^2.

Next, the transparent support used in the present invention will be described.

Examples of the transparent support include polyester films such as polyethylene terephthalate and polybutylene terephthalate, films of cellulose derivatives such as cellulose triacetate film, polystyrene films, polypropylene films, and polyolefin films such as polyethylene. It can be used alone or by pasting.

The thickness of the transparent support is 20 to 200 μm, and preferably 50 to 100 μm.

In the present invention, a subbing layer may be provided between the transparent support and the heat-sensitive layer in order to enhance the adhesion between the two layers. As the subbing layer material, gelatin or synthetic polymer latex,
Nitrocellulose or the like is used. The coating amount of the undercoat layer is 0.
It is preferably in the range of ^{1g / m 2 ~2.0g / m 2} , especially 0.2g
The range of / m ^{2 to} 1.0 g / m ² is preferred.

If it is less than 0.1 g / m ² , the adhesion between the support and the heat-sensitive layer will not be sufficient, and even if it is increased to 2.0 g / m ² or more, the adhesion between the support and the heat-sensitive layer will reach saturation, which is cost effective. Will be at a disadvantage.

When the heat-sensitive layer is coated on the undercoat layer, the image quality of the heat-sensitive layer may deteriorate if the water contained in the heat-sensitive layer causes the heat-sensitive layer to deteriorate in image quality. It is desirable to cure.

The following hardeners can be used in the present invention.

Divinylsulfone N, N'-ethylenebis (vinylsulfonylacetamide), 1,3-bis (vinylsulfonyl)
-2-propanol, methylene bismaleimide, 5-acetyl-1,3-diacryloyl-hexahydro-s-triazine, 1,3,5-triacryloyl-hexahydro-
Active vinyl compounds such as s-triazine, 1,3,5-trivinylsulfonyl-hexahydro-s-triazine.

2,4-dichloro-6-hydroxy-s-triazine
Sodium salt, 2,4-dichloro-6-methoxy-s-triazine, 2,4-dichloro-6- (4-sulfoanilino) -s-triazine sodium salt, 2,4-dichloro-6- (2-sulfo Ethylamino) -s-triazine,
Active halogen compounds such as NN'-bis (2-chloroethylcarbamyl) piperazine.

Bis (2,3-epoxypropyl) methylpropylammonium.p-toluenesulfonate, 1,4-bis (2 ', 3'-epoxypropyloxy) butane, 1,3,5
-Epoxy compounds such as triglycidyl isocyanurate, 1,3-diglycidyl-2- (γ-acetoxy-β-oxypropyl) isocyanurate.

Ethyleneimino compounds such as 2,4,6-triethylene-s-triazine, 1,6-hexamethylene-N, N'-bisethyleneurea and bis-β-ethyleneiminoethylthioether.

Methanesulfonic acid ester compounds such as 1,2-di (methanesulfonoxy) ethane, 1,4-di (methanesulfonoxy) butane, and 1,5-di (methanesulfonoxy) pentane.

Dicyclohexylcarbodiimide, 1-cyclohexyl-3- (3-trimethylaminopropyl) carbodiimide-p-trienesulfonate, 1-ethyl-3-
Carbodiimide compounds such as (3-dimethylaminopropyl) carbodiimide hydrochloride.

2,5-dimethylisoxazole / perchlorate, 2-
Isoxazole compounds such as ethyl-5-phenylisoxazole-3'-sulfonate and 5,5 '-(paraphenylene) bisisoxazole.

Inorganic compounds such as chromium alum and chromium acetate.

N-carbethoxy-2-isopropoxy-1,2-dihydroquinoline, N- (1-morpholinocarboxy)-
Dehydration condensation type peptide reagents such as 4-methylpyridinium chloride; active ester compounds such as N, N'-adipoyldioxydisuccinimide and N, N'-terephthaloyldioxydisuccinimide.

Isocyanates such as toluene-2,4-diisocyanate and 1,6-hexamethylene diisocyanate.

The amount of these hardeners added is based on the weight of the base coating material.
In the range of 0.20% by weight to 3.0% by weight, an appropriate addition amount can be selected according to the coating method and the desired degree of curing.

If the amount added is less than 0.20% by weight, the degree of cure will be insufficient regardless of the time, and the undercoat layer will swell when the heat-sensitive layer is applied. Conversely, if it is more than 3.0% by weight, the degree of cure will be insufficient. And the adhesion between the undercoat layer and the support deteriorates, and the undercoat layer becomes a film and peels off from the support.

Depending on the curing agent used, if necessary, caustic soda or the like may be further added to bring the pH of the solution to the alkaline side, or the pH of the solution may be brought to the acidic side with citric acid or the like.

It is also possible to add an antifoaming agent in order to eliminate bubbles generated during coating, or to add an activator to improve the leveling of the liquid and prevent the generation of coating streaks. .

Further, if necessary, an antistatic agent can be added.

Further, it is desirable to activate the surface of the support by a known method before applying the undercoat layer. As the method of activation treatment, etching treatment with acid, flame treatment with gas burner, or corona treatment, glow discharge treatment, etc. are used, but from the viewpoint of cost or simplicity, U.S. Pat.No. 2,715,075, the same. No. 2,846,727, No. 3,549,40
The corona discharge treatment described in No. 6, No. 3,590,107, etc. is most preferably used.

The coating liquid according to the present invention is a generally well-known coating method,
For example, dip coating method, air knife coating method, curtain coating method, roller coating method, doctor coating method,
It can be applied by a wire bar coating method, a slide coating method, a gravure coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294. US Patent No. 2,
761,791, 3,508,947, 2,941,898, 3,526,528 and Yuji Harazaki, "Coating Engineering", page 253 (Published by Asakura Shoten in 1973) It is also possible to apply simultaneously, and an appropriate method can be selected according to the application amount, the application speed and the like.

In the coating liquid used in the present invention, a pigment dispersant, a thickener, a flow modifier, a defoaming agent, a foam suppressant, a release agent, and a colorant may be appropriately blended as necessary as long as the characteristics are not impaired. It doesn't matter.

The heat-sensitive material of the present invention can be used as a sheet for printers of facsimiles and electronic computers that require high-speed recording. In this case, unlike a normal facsimile or printer, a device having a so-called double-sided thermal head capable of simultaneous thermal recording on both sides is desirable. It is also possible to perform thermal recording on the opposite side of the sheet that has been reversed and returned after performing single-sided recording using a conventional single thermal head. Further, when a diazo compound is used as a color-forming component, it is advantageous to have an exposure zone for photodecomposition especially in terms of image storability and multicoloring.

There are roughly two types of methods for arranging the print head and the exposure zone. One is to print once and then irradiate light for photodecomposition, and before and after this light irradiation, the recording material feeding mechanism allows the recording material to wait for printing so that it can be printed again at the place where it was once printed. Then, printing and light irradiation are repeated, and the operation of returning the recording material to its original position is repeated. This is the so-called 1-head multi-scan method, and the other is the recording head for the number of colors to be recorded. It is a so-called multi-head one-scan system in which a light irradiation zone is provided between them, and both systems may be combined if necessary.
Further, the thermal energy applied to the head may be changed if necessary. Further, as the light source for photolysis, various light sources that emit light of a desired wavelength can be used. For example, various fluorescent lamps, xenon lamps, xenon flash lamps, mercury lamps of various pressures, photographic flashes, strobes, etc. Various light sources can be used. Further, in order to make the optical fixing zone compact, the light source section and the exposure section may be separated by using an optical fiber.

In some cases, the multi-color sample can be obtained by placing the recording material, which has been printed once, under sunlight, fluorescent light, or the like, fixing mainly with light in the visible light region, and then printing again.

<< Effects of the Invention >> As described in detail above, according to the present invention, a multicolor image having excellent hue, excellent color separation, and good image storability which could not be obtained according to the thermal recording method can be obtained. be able to. Further, the present invention can make the obtained image a transmission image or a reflection image, and opens the way to natural color image formation by non-silver salt photography, and its significance is great.

<Example> The present invention will be further described with reference to the following examples, but the present invention is not limited thereto.

In addition, "part" indicating the addition amount represents "part by weight".

Preparation of capsule liquid A 63 parts of 8% by weight polyvinyl alcohol aqueous solution and 100 parts of distilled water
Part, and then emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle size of 2 μ. Next, the obtained emulsion was continuously stirred at 40 ° C. for 3 hours.

After cooling this solution to 20 ℃, Amberlite IR-120B
(Rohm and Haas (trade name)) (100 cc) was added, the mixture was stirred for 1 hour, and then filtered to obtain a capsule liquid A.

Preparation of Coupler / Base Dispersion A (Emulsified Dispersion) I. Polyvinyl alcohol 4% by weight aqueous solution 170 parts The solution of II was added to I, and the mixture was emulsified and dispersed at 20 ° C. to obtain an emulsified dispersion.

Preparation of Coupler / Base Dispersion Liquid B (Solid Dispersion) A coupler, a base and polyvinyl alcohol are mixed in the same composition ratio as coupler / base dispersion liquid A, and Dynomill (manufactured by Wheelie A. Bacofen A.G. ))
To obtain a dispersion liquid having an average particle size of 3 μm.

Preparation of Coloring Aid Dispersion A As Coloring Aid And dyno mill (Willie A. Bacofen.
Dispersed by A.G. (trade name), average particle size 3
A dispersion of μ was obtained.

Preparation of capsule liquid B Mix 100 parts of 8% by weight polyvinyl alcohol aqueous solution and 40 parts of distilled water
After being added to an aqueous solution of 1 part, the mixture was emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle size of 1 μm. Next, the obtained emulsion was continuously stirred at 40 ° C. for 3 hours to obtain a capsule liquid B.

Preparation of Capsule Liquid C The following compound (CIBA Pergascript
Red I-6-B) Was used to obtain a capsule liquid C in the same manner as the capsule liquid B.

Preparation of Developer Dispersion Liquid A (Emulsified Dispersion) 8 parts of the developer (a) represented by the following structural formula, 4 parts of (b) and 30 parts of (c) and 8 parts of 1-phenyl-1-xylylethane. And dissolved in 30 parts of ethyl acetate. The resulting developer solution was mixed with 100 parts of an 8% by weight polyvinyl alcohol aqueous solution and 150 parts of water.
Parts and an aqueous solution of 0.5 parts of sodium dodecylbenzene sulfonate were mixed and emulsified to obtain an emulsified dispersion having a particle size of 0.5 μm.

Developer (a) Developer (b) Developer (c) Preparation of Developer Dispersion Liquid B (Solid Dispersion) Polyvinyl alcohol (8% by weight) Water-soluble liquid 100 parts, water 1
To 50 parts, 8 parts of the developer (a), 4 parts of (b) and 30 parts of (c) were added and dispersed by Dynomill to obtain a dispersion liquid having an average particle diameter of 3 μm.

Preparation of coating liquid (1) Preparation of coating liquid A (cyan) Capsule liquid B 5.0 parts Developer dispersion A (emulsion dispersion) 10.0 parts Distilled water 5.0 parts was stirred and mixed to prepare coating liquid A.

(2) Preparation of coating liquid A '(cyan) Coating liquid A was prepared in the same manner as coating liquid A except that 10.0 parts of developer dispersion B (solid dispersion) was used in place of developer dispersion A. I got A '.

(3) Preparation of coating liquid B (magenta) Capsule liquid C 5.0 parts Developer dispersion A (emulsion dispersion) 10.0 parts Distilled water 5.0 parts was mixed with stirring to obtain coating liquid B.

(4) Preparation of coating liquid B '(magenta) Coating liquid B was prepared in the same manner as coating liquid B except that 10.0 parts of developer dispersion B (solid dispersion) was used in place of developer dispersion A. I got B '.

(5) Preparation of coating liquid C (yellow) Capsule liquid A 4.9 parts Hydroquinone 5% by weight aqueous solution 0.2 parts Coupler / base dispersion A 3.7 parts was stirred and mixed to prepare coating liquid C.

(2) Preparation of coating liquid C '(yellow) Coating liquid except that 3.7 parts of coupler / base dispersion B and 3.7 parts of color-forming auxiliary dispersion A were used instead of 3.7 parts of coupler / base dispersion A. A coating solution C ′ was obtained in the same manner as in C.

Preparation of Recording Sheet A A 75 μ-thick biaxially stretched polyethylene terephthalate film was used as a transparent support, both surfaces were subjected to corona treatment, and then coating solution A was applied to one surface and coating solution B was applied to the other surface. An intermediate layer having the following composition and a coating liquid C were sequentially applied, and the coating liquids A, B, and C each had a dry weight of 12 g / m ² , and that of the intermediate layer was
It was adjusted to ² g / m ² . Next, a protective layer having the same composition as that of the intermediate layer was provided on both sides at 2 g / m ² to obtain a recording sheet A.

Composition of the intermediate layer (protective layer) Silica-modified polyvinyl alcohol (PVA manufactured by Clera Co., Ltd.)
R2105) 1 part (solid content) Colloidal silica (Nissan Chemical Co., Ltd. Snowtex 3
0) 1.5 parts (solid content) Zinc stearate (Hydrin Z- manufactured by Chukyo Yushi Co., Ltd.)
7) 0.02 part (solid content) Paraffin wax (Hydrin P- manufactured by Chukyo Yushi Co., Ltd.)
7) 0.02 parts (solid content) Preparation of recording sheet B Recording sheet B was obtained in the same manner as recording sheet A except that coating liquid C ′ was used instead of coating liquid C.

Preparation of recording sheet C (for comparison) Instead of the coating liquids A, B and C, coating liquids A ′, B ′,
A recording sheet C was obtained in the same manner as the recording sheet A except that C ′ was used.

Preparation the coating solution A for clarity measurement sheet, A ', B, B', C, and 12 g / m ² was coated on each of the C 'the transparent support, followed by the protective layer provided 2 g / m ² sheet Recording sheets a, a ', b, b',
c and c '.

Example 1. Recording sheets A, B and C and a transparency measuring sheet a,
The haze (%) of each of the samples a ', b, b', c and c'was measured by an integrating sphere method HTR meter manufactured by Nippon Seimitsu Co., Ltd. (however, the recording sheets A, B and C are cyan. It is measured from the color side). The results are shown in the table.

Table 1 Haze (%) Transparency recording sheet a 16 good 〃 a'80 insufficient 〃 b 15 good 〃 b '82 insufficient 〃 c 17 good 〃 c' 81 insufficient recording sheet A 18 good recording sheet B 75 insufficient Recording Sheet C 95 Insufficient This result is microcapsules containing a diazo compound or a basic precursor as a core substance, and an emulsified dispersion obtained by emulsifying and dispersing a coupler or a color developer in an organic solvent insoluble in water. It is demonstrated that extremely good transparency can be obtained when a coating liquid containing the above is used.

Example 2. When several points were randomly heated on each side of the recording sheet A at 100 ° C. for 1 second using a heat block, yellow and cyan color developments appeared on both sides. Then, light is irradiated for 10 seconds with Ricopy Super Dry 100 type (400 to 430n
After m), it was further heated from the yellow color development side at 120 ° C. for 1 second using a heat block in the same manner, and the lower layer developed magenta.

As described above, when printing is performed at a low temperature before light irradiation, both surfaces of the recording sheet are colored yellow and cyan respectively, and then the light is irradiated to photolyze the diazo compound (yellow color forming layer), and then printing is performed at a slightly high temperature. The recording sheet developed magenta. As a result, when viewing this sheet as a transmission image from one side, the color images are cyan, magenta, yellow and blue (cyan + magenta), green, (cyan + yellow), red (yellow + magenta), black (cyan + magenta). A magenta + yellow) clear and colored image without unnecessary color mixture or color blur was obtained.

Example 3 Recording was performed on recording sheet B (Example 2) in the same manner as recording sheet A, and when viewed as a reflection image from the cyan color development side, the diazo layer portion on the opposite side which is substantially opaque. Shows a white background after being fixed by light, so that a clear multicolor image having clear reflection without any unnecessary color mixture or color blurring was obtained.

Comparative Example Recording was also performed on the recording sheet C in the same manner as the recording sheet A, but due to insufficient transparency of each color forming layer, it is inferior to the recording sheets A and B in terms of color separation and sharpness. It became a color image.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the heat-sensitive material of the present invention in which one color forming layer is provided on each side of the support. FIG. 2 is a cross-sectional view showing an example of the color development situation when thermal printing is performed on the heat-sensitive material of FIG. FIG. 3 is a sectional view of the heat-sensitive material of the present invention having three color-developing layers. FIG. 4 is a cross-sectional view showing the color development situation when thermal printing is performed on the heat-sensitive material of FIG. In the figure, reference numeral 1 is green, 2 is yellow, 3 is red,
4 is black, 5 is blue, 6 is cyan, and 7 is magenta.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Yamaguchi No. 200 Onakazato, Fujinomiya City, Shizuoka Prefecture, Fuji Photo Film Co., Ltd. (56) References JP-A-60-4092 (JP, A) JP-A-59-214691 (JP, A) JP 59-190886 (JP, A) JP 58-166345 (JP, A)

Claims (1)

[Claims] 1. A multicolor heat-sensitive recording material comprising at least one color forming unit layer capable of forming different hues on each surface of a transparent support, wherein at least one of the color forming unit layers is substantially transparent. And the color-forming component contained in the transparent color-forming unit layer is a combination of a diazonium salt and a coupler, or a combination of a basic dye precursor and a color developer,
Among the combined color-forming components, the diazo compound or basic dye precursor is encapsulated in microcapsules,
The coupler or developer coexisting with the microcapsules,
A multicolor heat-sensitive recording material, characterized by being dissolved in an organic solvent which is hardly soluble or insoluble in water, emulsified and dispersed, and then applied.