JPH02136286A - Multicolor thermal recording material - Google Patents

Abstract

PURPOSE:To enhance raw preservability or the like of a multicolor thermal recording material by providing at least one color forming unit layer each on either side of a transparent support, providing an opaque protective layer on an outermost layer on one side of the support, and providing a transparent protective layer on the outer side of the color forming unit layer on the other side of the support. CONSTITUTION:An opaque thermal magenta color forming layer 2 is provided on the back side of a transparent support 1, a transparent thermal cyan color forming layer 3 is provided on the face side, a transparent protective layer 4 is provided on the outer side of the cyan color forming layer 3, and an opaque protective layer 5 is provided on the outer side of the magenta color forming layer 2, thereby producing a multicolor thermal recording material. When an image is thermally recorded in the thermal color forming layers 2 and 3 from both sides by a thermal head, a cyan color and a magenta color can be developed independently on the opposite sides of the support 1 by the same applied energy. Since the support is transparent, development of cyan, cyan + magenta (= blue) and magenta colors can be realized with favorable color separation, as viewed from the side of the transparent protective layer 4.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a multicolor heat-sensitive recording material having a transparent heat-sensitive layer,
In particular, the present invention relates to a heat-sensitive recording material whose transparent heat-sensitive layer has good transparency stability and which can prevent unintended color development.

(Prior art) The thermal recording method has three advantages: (1) no development is required; (2) when the support is paper, the quality of the paper is similar to that of ordinary paper; (3) it is easy to handle; and (4) color density is high. (5) The recording device is simple and inexpensive; and (6) There is no noise during recording. Therefore, it has rapidly become popular in the fields of black and white facsimiles and printers in recent years. These heat-sensitive recording materials are made by coating a support such as paper or synthetic paper with a color former or developer, and are recorded using a heating process using a thermal head based on an electrical signal corresponding to the original. .

In the recording field as well, with the rapid development of the information industry, there is an increasing demand for easily obtaining color hard copies from information equipment terminals such as computers and facsimiles.

The present inventors, while conducting intensive research on heat-sensitive recording materials, adopted a combination of a diazo compound and a coupler as a coloring system, contained either the diazo compound or the coupler in microcapsules, and the other under certain conditions. When the two are mixed after emulsification and dispersion and coated on a support, the resulting heat-sensitive layer becomes substantially transparent, and the stability of the emulsion dispersion stabilizes the transparency of the heat-sensitive layer. We have found that this is extremely important in making it a reality.

(Problems to be Solved by the Invention) The present invention, etc., while considering multicolor heat-sensitive recording materials using the above-mentioned transparent heat-sensitive layer, has found that the images obtained in this way are It was found that there is room for further improvement, and that there is also room for further improvement in terms of uniformity of hue reproducibility.

As a result of intensive study to make the above improvements, the present inventors found that
One or more heat-sensitive layers capable of developing different hues are arranged on both sides of a transparent support, the outermost coloring layer on one side is opaque, and the haze of the other coloring layers is 60% or less, and , when a transparent protective layer is laminated on a substantially transparent heat-sensitive layer with a haze of 60% or less, and an opaque protective layer is laminated on an opaque heat-sensitive layer, image clarity is significantly improved. This paper found that if the transparent support used is thin, the heat-sensitive layer on the opposite side may be affected through the support when heat is applied, resulting in non-uniformity in hue reproducibility. invention has been achieved.

Therefore, the first object of the present invention is to provide a heat-sensitive recording material that can sufficiently control the number of color hues and color separation to obtain clear multicolor images and has excellent raw and archival properties. It's about doing.

A second object of the present invention is to provide a heat-sensitive recording material that can uniformly reproduce the hue of a multicolor image.

A third object of the present invention is to provide a multicolor thermosensitive recording material that is excellent not only in hue reproducibility but also in manufacturing suitability.

(Means for Solving the Problems) The above-mentioned aspects of the present invention are directed to a multicolor thermosensitive recording medium, in which one or more coloring unit layers each capable of developing a hue different from any coloring hue are provided on both sides of a transparent support. In the material, a transparent protective layer is created by laminating an opaque protective layer on the outermost coloring unit layer on one side and laminating a transparent protective layer on the coloring unit layer on the opposite side. As a multicolored reflective image can be seen from the side, among the color forming unit layers,
Substantially transparent heat-sensitive layers having a haze of 60% or less are disposed as at least all the color-forming unit layers except for the color-forming unit layer immediately below the opaque protective layer, and the thickness of the transparent support is 4.
A multicolor heat-sensitive recording material having a diameter of 0 μm or more, the transparent heat-sensitive layer having one or more heat-sensitive layers whose coloring system is a combination of a diazo compound and a coupler; A heat-sensitive layer formed by dissolving one of the two in an ester-based organic solvent that is sparingly soluble or insoluble in water, and then applying and drying a coating solution containing an emulsified dispersion as one component of the coloring system, which is emulsified and dispersed in the aqueous phase. This was achieved by using a multicolor heat-sensitive recording material that is characterized by:

Next, using the multicolor heat-sensitive recording material of the present invention, 1. A method for obtaining a clear multicolor image will be explained according to the drawings.

Figure 1 shows an opaque magenta heat-sensitive layer on the back side of a transparent support, a transparent cyan heat-sensitive layer on the front side, a transparent protective layer on top of the cyan heat-sensitive layer, and an opaque layer on top of the magenta heat-sensitive layer. The multicolor heat-sensitive recording material of the present invention is provided with a protective layer.

Both heat-sensitive layers are assumed to develop color with the same applied heating energy,
By thermally recording images on both sides using a thermal pen or a thermal head, it is possible to independently develop cyan and magenta colors on both sides of the support, as shown in FIG. 2, with substantially the same applied energy.

Moreover, since the support is substantially transparent, as a result, cyan, cyan+magenta (blue), and magenta can be developed with good color separation when viewed from the transparent protective layer side. In this case, the reflected image is extremely clear because not only the magenta heat-sensitive layer is opaque, but also the opaque protective layer provided thereon completes the opacity (see Figure 2). reference). In addition, since the thickness of the transparent support is 40 mμ or more, the thermal energy during recording on one side will not be transmitted to the heat-sensitive layer on the other side and cause a coloring reaction, so the hue on each side will be perfect. independently reproduced.

The above description describes the case of two coloring units, cyan and magenta, but basically the same applies when the coloring unit consists of three coloring units, cyan, magenta, and yellow. A transparent heat-sensitive layer that develops a yellow color is provided between the heat-sensitive layer and the transparent protective layer (see Figure 3).In this case, in order to develop the three colors independently, a diazo compound is added to the color-forming system of one or more heat-sensitive layers. In FIG. 3, a coloring system consisting of a combination of a diazo compound and a coupler is used as the coloring system of at least the transparent yellow thermosensitive layer. That is, first of all, a coloring system consisting of a combination of a diazo compound and a coupler is used. Then, the yellow layer and magenta layer on both outer surfaces of the support are independently colored by thermal recording with low thermal energy.

Thereafter, photofixing is performed using a light source with a specific wavelength that photodecomposes the diazo compound in the yellow thermosensitive layer. Next, by thermally recording the inner cyan layer, which has low heat sensitivity, with relatively higher thermal energy than the previous time, cyan, magenta, and yellow can be independently developed on both sides of the support. Furthermore, the thermal energy used to develop the color of the cyan layer does not place an excessive burden on the recording material and apparatus, and therefore has great practical significance.

As a result, when viewed from the side of the transparent protective layer, cyan, magenta, yellow, cyan + magenta (blue), magenta + yellow (red), cyan + yellow (clean), cyan + This means that a total of seven basic colors, magenta + yellow (black), can be realized with good color separation (see Figure 4). In this case, the reflected image is extremely clear because not only the magenta heat-sensitive layer is made opaque, but also the opaque protective layer provided thereon completes the opacity. Furthermore, those skilled in the art can easily understand that by controlling the color development of each unit by appropriately adjusting the applied heating energy, the number of colors that can be achieved by color mixing can be synergistically increased. . In this case as well, since the thickness of the transparent support is 40 mμ or more, even when the heat-sensitive layer on one side is colored, it does not affect the heat-sensitive layer on the opposite side at all, resulting in a good multicolor image. Can be reproduced.

Above, an example of the multicolor coloring process of the present invention has been schematically shown, but the material used for the heat-sensitive recording material of the present invention is a component that causes a coloring reaction based on contact with a substance by heating,
Specifically, these are a combination of a diazo compound and a coupler, and a combination of an acidic substance and an electron-donating dye precursor. However, since it can be photofixed, it is preferable to employ a combination of a diazo compound and a coupler in one or more heat-sensitive layers as a coloring system for a transparent heat-sensitive layer, and by incorporating such a heat-sensitive layer, the heat-sensitive layer can be stacked in two or more layers.

As the electron-donating dye precursor used in the present invention, a colorless or light-colored one is appropriately selected from known compounds that develop color by donating electrons or accepting protons such as acids. Such compounds have partial skeletons such as lactones, lactams, sultones, spiropyrans, esters, and amides, and these partial skeletons are ring-opened or cleaved upon contact with a color developer. Preferred compounds include Examples include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, spiropyran compounds, etc., and specific examples include crystal violet lactone, benzoylleucomethylene blue, malachite green lactone, and rhodamine B lactam. , 1,3゜3-trimethyl-6゛-ethyl-8゛-butoxyindolinobenzospiropyran and the like.

The color developer that causes a color-forming reaction with the electron-donating dye precursor used in the present invention can be appropriately selected from known ones and used. For example, color developers for leuco dyes include phenolic compounds, sulfur-containing phenolic compounds, carboxylic acid compounds, sulfonic compounds, urea-based or thiourea-based compounds, etc. For details, see, for example, Paper Valve Technology Times. (1985) pp. 49-54 and 65-70. Among these, those having a melting point of 50°C to 250'C are particularly preferred, and phenols and organic acids that are sparingly soluble in water and having a melting point of 60°C to 200'C are particularly desirable. Further, it is preferable to use two or more types of color developers in combination because the solubility increases when the color developer is thick.

Further, if necessary, a photofading inhibitor described in, for example, JP-A-61-283589, JP-A-61-283590, and JP-A-61-283591 can be appropriately added.

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 color developer called a coupling component, which will be described later. It is a photodegradable diazo compound that decomposes when exposed to light and no longer has the ability to develop color even when a coupling component acts on it. The hue in this coloring system is
It is approximately determined by the diazo dye produced by the reaction between 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. Can be done.

The photodegradable diazo compound referred to in the present invention mainly refers to aromatic diazo compounds, and more specifically refers to compounds such as aromatic diazonium salts, diazosulfonate compounds, and diazoamino compounds. Hereinafter, explanation will be given mainly using diazonium salts as examples.

It is generally said that the photodecomposition wavelength of a diazonium salt is its maximum absorption wavelength. Also, the maximum absorption wavelength of diazonium salts varies from about 200 nm to 700 nm, depending on their chemical structure.
It is known that the change occurs down to nm level (“Photodecomposition and chemical structure of photosensitive diazonium salts” by Takahiro Tsunoda and Ao Yamaoka)
Journal of the Photographic Society of Japan 29 (4) pp. 197-205 (19
65)).

That is, when a diazonium salt is used as a photodegradable compound, it is decomposed by light of a specific wavelength depending on its chemical structure. Furthermore, by changing the chemical structure of the diazonium salt, the hue of the dye after the reaction can be changed even when the same coupling component is used for the coupling reaction.

A diazonium salt is a compound represented by the general formula ArN, "X-" (wherein Ar represents a substituted or unsubstituted aromatic moiety, N2 represents a diazonium group, and X- represents an acid anion. Hail,).

Among these, compounds having a photolysis wavelength around 400 nm include 4-diazo-1-dimethylaminobenzene,
4-Diazo-1-diethylaminobenzene, 4-diazo-1-dipropylaminobenzene, 4-diazo-1-methylbenzylaminobenzene, 4-diazo-1-dibenzylaminobenzene, 4-diazo-1-ethylhydroxy Ethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1=dimethylamino-2-methylbenzene, 4-diazo-1-benzoylamino-2,5-jethoxybenzene, 4- Diazo-1-morpholinobenzene, 4-diazo-1-morpholino-2,5-jethoxybenzene, 4-diazo-1-
Morpholino-2゜5-dibutoxybenzene, 4-diazo-1-anilinobenzene, 4-diazo-1-tolylmercapto-2,5-jethoxybenzene, 4-diazo-
Examples include 1,4-methoxybenzoylamino-2,5-jethoxybenzene. 300-370
Compounds having a photolysis wavelength in nm include 1-diazo-4-(N,N-dioctylcarbamoyl)benzene,
1-Diazo-2-octadecyloxybenzene, 1-diazo-4-(4-tert-octylphenoxy)benzene, 1-diazo-4-(24-di-tert-amylphenoxy)benzene, 1-sia'/' -2-(4-t
ert-octylphenoxy)benzene, l-diazo-
5-chloro-2-(4-tert-octylphenoxy)benzene, 1-diazo-2,5-bis-octadecyloxybenzene, 1-diazo-2,4-bis-octadecyloxybenzene, 1-diazo-4- (N-octylteraroylamino)benzene and the like can be mentioned.

The aromatic diazonium compounds typified by the examples listed above can have a wide range of photodecomposition wavelengths by arbitrarily changing their substituents.

Specific examples of acid anions include C, F, ..., C00-
(n represents 3 to 9), CM F! N14I
SO, - (m represents 2 to 8), (Ct Fz L,
l5o2)z CH- (l represents 1 to 18), H Specific examples of the diazo compound (diazonium salt) include the following examples.

Can be mentioned.

C (CH3) y OCR.

0 CaH9 The diazosulfonate compound that can be used in the present invention is a compound represented by the general formula. In the formula, R+ is an alkali metal or an ammonium compound, Rz, R1, Rs and R6
is hydrogen, halogen, alkyl group, or alkoxy group, and R4 is hydrogen, halogen, alkyl group, amino group, benzoylamido group, morpholino group, trimercapto group, or pyrrolidino group.

A large number of such diazosulfonates are known and can be obtained by treating each diazonium salt with a sulfite.

Preferred compounds among these compounds include 2-methoxy, 2-phenoxy, 2-methoxy-4-phenoxy, 2,4-dimethoxy, 2-methyl-4-methoxy,
Benzenediazosulfonate having a substituent such as 2,4-dimethyl, 2.4゜6-trimethyl, 4-phenyl, 4-phenoxy, 4-acetamide, or 4-(
N-ethyl, N-benzylamino), 4-(N,N-dimethylamino), 4 (N,N-diethylamino)
, 4-(N,N-diethylamino)-3-monochloro, 4
-pyrogeno-3-chlor, 4-morpholino-2-methoxy, 4-(4'-methoxybenzoylamino")-2
, 5-dibutoxy, 4-(4°-trimercapto)-2
, 5-dimethoxy, and the like. When using these diazosulfonate compounds, it is desirable to irradiate the diazosulfonate with light to activate the diazosulfonate before printing.

Further, other diazo compounds that can be used in the present invention include diazoamino compounds. The diazoamino compound is a compound in which a diazo group is coupled with dicyandiamide, sarcosine, methyltaurine, N-ethylanthranittaic acid-5-sulfonic acid, monoethanolamine, jetanolamine, guanidine, or the like.

The coupler used in the present invention is one that forms a dye by coupling with a diazo compound (diazonium salt), and specific examples include resorcin, phloroglucin, 2,
Sodium 3-hydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1゜5-dihydroxynaphthalene, 2.3-dihydroxynaphthalene, 2.3-dihydroxy-6-sulfanylnaphthalene, 2- Hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid-2°-methylamide, 2-hydroxy-3-
Naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyl-oxy-probylamide, 2-hydroxy-3-naphthoic acid tetradodecylamide, acetanilide, acetoacetanilide , benzoylacetanilide, 1-phenyl-3-methyl-5-pyrazolone,
2.4-bis(benzoylacetamino)toluene, 1
, 3-bis(pivaloylacetaminomethyl)benzene, 1-(2", 4").

6'-)IJdichloroenyl)-3-benzamido-5-pyrazolone, 1-(2',4°,6'trichlorophenyl)-3-anilino-5-pyrazolone, 1-phenyl-3-phenylacetamide- Examples include 5-pyrazolone and the like.

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

As the basic substance, a poorly water-soluble or water-insoluble basic substance or a substance that generates an alkali when heated is used. Examples include inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines 1, indoles, imidazoles, imidacillins, triazoles. Examples include nitrogen-containing compounds such as morpholines, piperidines, amidines, formazines, and pyridines. Specific examples of these are:
For example, it is described in Japanese Patent Application No. 60-132990.

Two or more basic substances may be used in combination.

Materials that produce the above color reaction are selected from the viewpoint of improving the transparency of the heat-sensitive layer, from the viewpoint of shelf life (preventing fogging) by preventing contact between the color forming agent and color developer at room temperature, and from the viewpoint of color development with the desired impression heating energy. It is preferable to encapsulate and use a part of the components essential for color development from the viewpoint of controlling the color development sensitivity.

The type of microcapsule used in this case is not particularly limited, but microcapsules that are particularly preferred in the present invention prevent contact between substances inside and outside the capsule due to the substance isolation effect of the microcapsule wall at room temperature; The permeability of the substance increases only while it is heated above this level.

In this case, the permeation start temperature can be freely controlled by appropriately selecting the capsule wall material, capsule core material, and additives. The transmission start temperature in this case corresponds to the glass transition temperature of the capsule wall (for example, Japanese Patent Application Laid-Open No. 59-91438, Japanese Patent Application No. 59-19088).
No. 6, see Japanese Patent Application No. 59-99490).

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, etc. . In the present invention, two or more of these polymeric substances can also be used in combination.

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

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

Here, the organic solvent for forming oil droplets can generally be appropriately selected from high boiling point oils, but
In particular, when using an organic solvent suitable for dissolving the diazo compounds, couplers, electron-donating dye precursors, color developers, etc. that cause color reactions, which will be described later, the color density and color development during thermal printing may be affected. This is preferable because the speed can be increased and fog can be reduced.

When producing microcapsules, they can be made from an emulsion containing 0.2% by weight or more of the component to be microencapsulated.

The preferred microcapsules produced as described above are not ruptured by heat or pressure as is used in conventional recording materials, and the reactive substances contained in the core and outside of the microcapsules are not destroyed by the microcapsule walls. can pass through and react.

The amount of coloring agent used is preferably 0.1 to 10 parts by weight of the coupling component and 0.1 to 20 parts by weight of the basic substance per 1 part by weight of the diazo compound.
On the other hand, it is preferable to use 0.3 to 160 parts by weight, preferably 0.3 to 80 parts by weight, of the color developer per 1 part by weight of the electron-donating dye precursor.

In the present invention, it is also possible to use a color development aid. This color development aid is a substance that increases the color density during thermal printing or lowers the minimum color development temperature, and lowers the melting point of coupling components, basic substances, color formers, color developers, or diazo compounds. This is to create a situation in which diazo, basic substances, coupling components, color formers, and color developers are more likely to react by lowering the softening point of the capsule wall.

Coloring aids include phenolic compounds, alcoholic compounds, amide compounds, sulfonamide compounds, etc.
Specific examples include p-tert-octylphenol, p-benzyloxyphenol, p-, tt-phenyl cybenzoate, benzyl carbanylate, phenethyl carbanylate, hydroquinone dihydroxyethyl ether, xylylene diol, N-hydroxyethyl-methane. Compounds such as sulfonic acid amide and N-phenyl-methanesulfonic acid amide can be mentioned. These may be contained in the core material 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, the diazo compound is used as a color developer for the electron-donating dye precursor (hereinafter, the term "color developer" also includes the coupling component described above). ) is dissolved in an organic solvent that is sparingly soluble or insoluble in water, and then mixed with an aqueous phase containing a surfactant and a water-soluble polymer as a protective colloid, resulting in an emulsified dispersion. Use in the form of objects.

The organic solvent for dissolving the color developer can be appropriately selected from high-boiling point oils, but in particular, organic solvents that have two or more benzene rings and are known as esters and pressure-sensitive oils.
The following general formulas (I) to (I
li) and triallylmethane (e.g. tritolylmethane, tolyldiphenylmethane)
, terphenyl compounds (e.g. terphenyl), alkyl compounds, alkylated diphenyl ethers (e.g.
propyl diphenyl ether), hydrogenated terphenyl (eg, hexahydro terphenyl), diphenyl ether, and the like. Among them, it is preferable to use esters with a high boiling point to form an emulsified dispersion of a color developer.
1 represents an alkyl group having 1 to 1 carbon atoms. P'%
q' represents an integer of 1 to 4, and the total number of alkyl groups is 4 or less.

In addition, the alkyl group of R1 and R1 is preferably an alkyl group having 1 to 8 carbon atoms.

In the formula, Rff" represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and R4 represents an alkyl group having 1 to 12 carbon atoms.n
represents 1 or 2.

pt and qt represent integers from 1 to 4. In the case of 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.

(III) (n) In the formula, Rs and R6 represent a hydrogen atom or the same or different alkyl group having 1 to 18 carbon atoms.

m represents an integer from 1 to 13. p2, q'' is 1~
represents an integer of 3, and the total number of alkyl groups is 3 or less.

In addition, the alkyl group of R5 and R& is particularly preferably an alkyl group having 2 to 4 carbon atoms.

Examples of the compound represented by formula (1) include dimethylnaphthalene, diethylnaphthalene, diisopropylnaphthalene, and the like.

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

Examples of compounds represented by formula (III) include 1-methyl-agedimethylphenyl-1-phenylmethane, 1-ethyl-1-dimethylphenyl-1-phenylmethane, and 1-phenylmethane.
-propyl-1-dimethylphenyl-1-phenylmethane.

Examples of high-boiling esters include phosphoric esters (e.g.
Triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate, talesyl diphenyl phosphate), phthalate esters (dibutyl phthalate, 2-ethylhexyl phthalate, ethyl phthalate, octyl phthalate, butylbenzyl phthalate), tetrahydrophthalate Dioctyl acid, benzoate ester (ethyl benzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, benzyl benzoate), abietate ester (ethyl abietate,
benzyl abietate), dioctyl adipate, isodecyl succinate, dioctyl azelate, oxalate esters (dibutyl oxalate, diventyl oxalate), diethyl malonate, maleate esters (dimethyl maleate, diethyl maleate, dibutyl maleate) , tributyl citrate, sorbate esters (methyl sorbate, ethyl sorbate, butyl sorbate), sebacate esters (dibutyl sebacate, dioctyl sebacate), ethylene glycol ester W4 (formic acid monoester and diester, butyric acid monoester and diesters, lauric acid monoesters and diesters, palmitic acid monoesters and diesters, stearic acid monoesters and diesters, oleic acid monoesters and diesters), triacetin, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, boric acid esters tributyl acid, tripentyl borate), etc.

It is also possible to use the above oils together or with other oils.

In the present invention, an auxiliary solvent may be added to the above-mentioned organic solvent as a low boiling point dissolution aid. Particularly preferred examples of such co-solvents include ethyl acetate, isopropyl acetate, butyl acetate and methylene chloride.

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

Further, as the surfactant to be contained in the aqueous phase, one can be appropriately selected from anionic or nonionic surfactants that do not cause precipitation or aggregation by interacting with the above-mentioned protective colloid. .

Preferred surfactants include sodium alkylbenzenesulfonate (eg, sodium lauryl sulfate), dioctyl sodium sulfosuccinate, polyalkylene glycol (eg, polyoxyethylene nonylphenyl ether), and the like.

The emulsified dispersion of a color developer in the present invention is produced by mixing an oil phase containing a color developer and an aqueous phase containing a protective colloid and a surfactant by means commonly used for fine particle emulsification, such as high-speed stirring and ultrasonic dispersion. It can be easily mixed and dispersed using.

At this time, the oil droplet size (diameter) of the color developer emulsion dispersion is preferably 7 μm or less in order to obtain a transparent heat-sensitive layer with a haze of 60% or less. More preferably, it is within the range of 0.1 to 5μ.

In addition, the ratio of the oil phase to the water phase (oil phase weight/water phase weight) is:
0.02 to 0.6 is preferable, more preferably 0.1 to
It is 0.4. If it is less than 0.02, the aqueous phase will be too large and it will be diluted, making it impossible to obtain sufficient color development, while if it is more than 0.6, the viscosity of the liquid will increase, resulting in inconvenience in handling and a decrease in transparency.

In addition to the above materials, acid stabilizers such as citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, and pyrophosphoric acid are used in the heat-sensitive layer whose coloring system is a combination of an electron-donating dye precursor and a color developer. Can be added.

In addition, the heat-sensitive recording material of the present invention can be viewed as a reflected image from one side of the transparent support, but the image becomes dull especially if the back side of the background part is visible, so recording is performed to make it appear white. The outermost layer on the reflective side, which is the side on which the image is viewed, is preferably a conventional opaque heat-sensitive layer, more preferably a white pigment is added to increase the opacity;
Furthermore, an opaque protective layer containing a white pigment is provided thereon as described below.

Examples of preferred 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.

When making the outermost coloring layer itself opaque by using a coloring component other than diazo, a color developer component, etc., these can be sanded or
It is preferable to use a solid dispersion using a mill or the like. in this case,
Water-soluble polymers separately? distributed in fl'e. 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 coloring components other than diazo and the color developer are added to the water-soluble polymer solution in an amount of 5 to 40% by weight, respectively.

The dispersed particle size is preferably less than lOμ.

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

Binders include polyvinyl, alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex 1, polyvinyl acetate, polyacrylic acid ester, ethylene-acetic acid. Various emulsions such as vinyl copolymers can be used. The amount used is 0.5 to 5 g in terms of solid content.

Also, the coating amount of the heat-sensitive layer is 3g/bo~20g/bo, especially 5g/bo
It is preferably between /rrr and 15g/rrf.

Sufficient sensitivity cannot be obtained below 3 g/%, and 20 g/r
Even if more than rr is applied, no improvement in quality will be seen, which will be disadvantageous in terms of cost.

In the heat-sensitive layer of the present invention, all layers except the outermost layer on one side of the support must be substantially transparent in order to improve color separation. The outermost layer may be transparent or opaque. Substantially transparent herein means that the haze (%) (measured with an integrating sphere HTR meter manufactured by Nippon Seimitsu Kogyo ■) must be 60% or less. It is preferably 40% or less, more preferably 30% or less. However, the transparency of the actual heat-sensitive layer test sample is based on the minute irregularities on the surface of the heat-sensitive layer (light scattering has a large influence. Therefore, the inherent transparency of the heat-sensitive layer, which is the problem in the present invention, When measuring the transparency inside the heat-sensitive layer using a haze meter, a convenient method is to attach a transparent adhesive tape onto the heat-sensitive layer and evaluate the measured value by substantially excluding surface scattering.

The transparent protective layer provided in the present invention consists of at least silicon-modified polyvinyl alcohol and colloidal silica.

The silicon-modified polyvinyl alcohol used in the present invention is
There are no particular limitations as long as the silicon atom is contained in the molecule, but the silicon atom usually contained in the molecule is an alkoxyl group, an acyloxyl group, a hydroxyl group obtained by hydrolysis, etc., or an alkali metal salt thereof, etc. It is preferable to use a compound having a reactive substituent.

Details of the method for producing modified polyvinyl alcohol containing silicon atoms in the molecule are given in JP-A-58-193189.
It is listed in the issue announcement.

The colloidal silica used in the present invention is used as a colloidal solution in which ultrafine particles of silicic anhydride are dispersed in water using water as a dispersion medium. The colloidal silica particles preferably have a particle size of 10 mμ to 100 mμ and a specific gravity of 1.1 to 1.3. The pH value of the colloidal solution in this case is about 4 to about 1
0 is preferably used.

When the protective layer is provided on the surface of the heat-sensitive recording material, the surface scattering phenomenon is suppressed in the same way as when the transparent adhesive tape is applied, and surprisingly, the transparency of the protective layer is extremely good. Furthermore, since the mechanical strength of the heat-sensitive layer surface is improved, the transparency of the entire heat-sensitive material can be further significantly improved.

A suitable blending ratio of silicon-modified polyvinyl alcohol and colloidal silica in the present invention is 0.00 parts by weight of colloidal silica to 1 part by weight of silicon-modified polyvinyl alcohol.
The amount is 5 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 will be small, and if it is used more than 3 parts by weight, cracks will occur in the protective layer, and the transparency will be reduced.

The protective layer may further contain one or more polymers. Specific examples of polymers that can be used in combination include methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, and styrene-maleic anhydride copolymer half ester. Water-soluble polymers such as hydrolysates, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide derivatives, polyvinylpyrrolidone, sodium polystyrene sulfonate, sodium alginate, styrene-butadiene rubber latex, acrylonitrile-brassene rubber latex, methyl acrylate -Water-insoluble polymers such as butadiene rubber latex and polyvinyl acetate emulsion can be mentioned. The amount used in combination is 0.01 to 0 per 1 part by weight of silicon-modified polyvinyl alcohol.
．． 5 parts by weight is preferred.

Pigments, metal soaps, wax, crosslinking 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 the water resistance of the protective layer.

The pigment has a refractive index of 1.4 to 1.55 and a particle size of II! The following pigments are preferred. Specifically, there are calcium carbonate, talc, Rouseki, kaolin, aluminum hydroxide, amorphous silica, etc., and the amount of these added is 0.05 to 0.05 of the total weight of the polymer.
The amount is 0.5 times, particularly preferably 0.1 to 0.3 times. If the amount is less than 0.05 times, it is ineffective in improving the matching property with the head, and if the amount is more than 0.5 times, the transparency and sensitivity of the heat-sensitive recording material will be significantly reduced, impairing its commercial value.

Metal soaps include emulsions of higher fatty acid metal salts such as zinc stearate, calcium stearate, aluminum stearate, etc., and the wall weight is 0.5 to 20% by weight, preferably 1 to 10% by weight of the total weight of the protective layer. is added in an amount of Waxes include emulsions such as paraffin wax, microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, silicone, etc., and their content is 0.5 to 40% by weight of the total weight of the protective layer.
It is preferably added in a proportion of 1 to 20% by weight.

In addition, the heat-sensitive layer is evenly maintained on the top! In order to form the layer, a surfactant is added to the coating solution for forming the protective layer. Surfactants include sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, etc. Specifically, sodium salts or ammonium salts of di(2-ethylhexyl)sulfosuccinic acid, di(n-hexyl)sulfosuccinic acid, etc. etc.

A surfactant, a polymer electrolyte, etc. may be further added to the protective layer to prevent charging of the heat-sensitive recording material. The solid content coating amount of the protective layer is usually preferably 0.2 to 5 g/nf, more preferably 1 g to 3 g/nf.

On the other hand, the composition of the first opaque layer provided in the present invention is the same as that of the transparent protective layer except that the combination of silicon-modified polyvinyl alcohol and colloidal silica used in the transparent protective layer is not used. It is preferable to use various pigments to improve the It is preferable to use these pigments in an amount of 0.1 to 3 times, especially 0.3 to 2 times, the total weight of the polymer, with a particle size of 0.01 μm to 8 μm, and in particular pigments with a refractive index of 1.55 or more. Preferably, white pigments are used.

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

The transparent supports mentioned here include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate films, polystyrene films, polypropylene films, polyolefin films such as polyethylene, etc. It can be used alone or in combination.

In the present invention, the thickness of the transparent support is 40 μm or more,
Preferably it is set to 55 μm to 100 μm. If the thickness of the support is less than 40 μm, the heat-insulating properties of the support during heat-sensitive recording are insufficient, so that the heat-sensitive layer on the other side is completely prevented from coloring due to the heat-sensitive recording signal on each side. This is undesirable because the reproducibility of the hue will vary depending on the strength of this influence, and feeding defects within the printer are likely to occur, causing color misregistration.

In the present invention, an undercoat layer can be provided between the transparent support and the heat-sensitive layer in order to enhance adhesion between the two layers. Gelatin, synthetic polymer latex, nitrocellulose, etc. are used as the material for the undercoat layer. The coating amount of the undercoat layer is O,
Ig/rrf~2. It is preferably in the range of 0.2 g/rrr to 1.0 g/rrr. A range of Og/rrf is preferred.

If it is less than 0.1 g/rrf, the adhesion between the support and the heat-sensitive layer will not be sufficient; Even if it is increased to more than Og/rd, the adhesive force between the support and the heat-sensitive layer reaches saturation, which is disadvantageous in terms of cost.

If the undercoat layer swells due to the water contained in the coating solution when the heat-sensitive layer is coated on top of it, the image quality of the heat-sensitive layer may deteriorate, so a hardening agent is not used for the undercoat layer. It is desirable to cure it.

As hardeners that can be used in the present invention, the following can be mentioned.

■Divinylsulfone N,N'-ethylenebis(vinylsulfonylacetamide), 1,3-bis(vinylsulfonyl)-2-propatol, methylenebismaleimide,
5-acetyl-1,3-diacryloyl-hexahydro-5-)riazine, 1.3.5-)lyacryloyl-hexahydro-3-triazine, 1,3.5-)rivinylsulfonyl-hexahydro- 5-) Active vinyl compounds such as riazine.

■2.4-dichloro-6-hydroxy-S-triazine sodium salt, 2.4-dichloro-6-medoxy S
-) riazine, 2,4-dichloro-6-(4-sulfoanilino)-s-triazine sodium salt, 2,4-dichloro-6-(2-sulfoethylamino)-S-) riazine, N-N' Active halogen compounds such as monobis(2-chloroethylcarbamyl)piperazine.

■Bis(2,3-epoxypropyl)methylpropylammonium p-)luenesulfonate, 1,4-bis(2',3'-epoxypropyloxy)butane, 1
．． 3.5-triglycidyl isocyanurate, 1,3-
Epoxy compounds such as diglycidyl-5-(γ-acetoxyβ-oxypropyl)isocyanurate.

■2,4.6-) lyethylene-s-) riazine, 1.6
Ethyleneimino compounds such as -hexamethylene-N,N'-bisethyleneurea and bis-β-ethyleneiminoethylthioether.

■1,2-di(methanesulfonoxy)ethane, 1.4
- Methanesulfonic acid ester compounds such as di(methanesulfonoxy)butane and 1°5-di(methanesulfonoxy)pentane.

■Dicyclohexylcarbodiimide, 1-cyclohexyl-3-(3-trimethylaminopropyl)carbodiimide-p-trienesulfonate, 1-ethyl-3-(
3-dimethylaminopropyl) carbodiimide hydrochloride.

■2.5-dimethylisoxazole perchlorate, 2
Inoxazole compounds such as -ethyl-5-phenylisoxazole-3°-sulfonate and 5.5'-(paraphenylene)bisisoxazole.

■Inorganic compounds such as chromium alum and chromium acetate.

■N-carboethoxy-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'-aziboyldioxydisuccinimide, and N,N'terephthaloyldioxydisuccinimide.

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

■Dialdehydes such as glutaraldehyde, glyoxal, dimethoxyurea, and 2,3-hydroxy-1,4-dioxane.

The amount of these hardeners added is based on the weight of the base coat material.
An appropriate addition amount can be selected in the range of 0.20% by weight to 3.0% by weight depending on the coating method and desired degree of curing.

If the amount added is less than 0.20% by weight, the degree of curing will be insufficient no matter how long it is left, and the undercoat layer will swell when applying the raging layer. If the amount is too large, the degree of curing progresses too much, which worsens the adhesion between the undercoat layer and the support, which has the disadvantage that the undercoat layer becomes film-like and peels off from the support.

Depending on the curing agent used, if necessary, the pH of the solution can be made alkaline by adding caustic soda or the like, or the pH of the solution can be made acidic by adding citric acid or the like.

It is also possible to add an antifoaming agent to eliminate foam generated during coating, or to add an activator to improve liquid leveling and prevent coating streaks. .

Moreover, it is also possible to add an antistatic agent if necessary.

Furthermore, before applying the undercoat layer, it is desirable to activate the surface of the support by a known method.

Activation treatment methods include acid etching treatment,
Flame treatment using a gas burner, corona treatment, glow discharge treatment, etc. are used, but from the point of view of cost or simplicity, U.S. Pat.
No. 846,727, No. 3,549,406, No. 3
, 590, 107, etc., is most preferably used.

The coating liquid according to the present invention can be applied by a generally well-known coating method,
For example, dip coating method, air knife coating method, curtain coating method, roller coating method, doctor coating method,
Coating can be performed by a wire barcode method, a slide coating method, a gravure coating method, or an extrusion coating method using a hopper as described in US Pat. No. 2,681,294. U.S. Pat. No. 2,761,791 and U.S. Pat. No. 3,508,947 as appropriate.
No. 2,941,898, and No. 3゜526.
Specification No. 528, Yuji Harasaki, "Coating Engineering" 25
It is also possible to apply the coating simultaneously in two or more layers using the method described in page 3 (published by Asakura Shoten in 1973), etc., and an appropriate method can be selected depending on the amount of coating, coating speed, etc. .

Pigment dispersants, thickeners, flow modifiers, antifoaming agents, mold release agents, and colorants may be appropriately added to the coating liquid used in the present invention as long as they do not impair the properties. The heat-sensitive recording material of the present invention can be used as a multicolor sheet for facsimiles and computer printers that require high-speed recording. In this case, unlike ordinary facsimiles and printers, it is desirable to use a device that has so-called double-sided thermal heads that can perform thermal recording on both sides simultaneously. It is also possible to record on one side using a conventional single thermal head and then turn the sheet over to thermally record the opposite side. Further, in the present invention, since at least one of the heat-sensitive layers contains a diazo compound as a color-forming component, it is particularly advantageous for image storage stability and multicolorization to have an exposure zone for photolysis.

There are roughly two types of methods for arranging print heads and exposure zones. One is to irradiate light for photodecomposition after printing once, and before and after this irradiation, the recording material feed mechanism allows the recording material to reach the waiting period for printing so that it can be printed again at the place where it has been printed once. There is a so-called one-head multi-scan method that repeats the operation of returning to the state, printing again, and returning the recording material to the storage.The other method has as many recording heads as the number of colors to be recorded, and This is a so-called multi-head one-scan method which has a light irradiation zone on both sides, and both methods may be combined as necessary.

Further, the thermal energy applied to the head may be changed as necessary. In addition, as a light source for photolysis, various light sources that emit light of a desired wavelength can be used, such as various fluorescent lamps, xenon lamps, xenon flash lamps, mercury lamps of various pressures, photographic flashes, and strobes. Equal volumes of 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 using an optical fiber. Also, in some cases,
It is also possible to obtain a multicolor sample by placing the printed recording material under sunlight or a fluorescent lamp, fixing it mainly with light in the visible region, and then printing again.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to obtain a multicolor image with excellent hue, excellent color separation property, and good image storage stability, which could not be obtained conventionally by a thermal recording method. be able to. Furthermore, since the heat-sensitive layer has good transparency stability, raw storage properties and recording storage properties are also good.

Furthermore, since the thickness of the support is 40 μm or more, it has good heat insulation properties, and thermal printing on one side does not affect other sides. It is easy to develop each hue completely independently, and it is also easy to stack two or more heat-sensitive layers.

(Example) The present invention will be further explained with reference to Examples below, but the present invention is not limited thereto.

Note that "parts" indicating the amount added represent "parts by weight."

The following diazo compound 3.4 parts Tricresyl phosphate 6 parts Methylene chloride 12 parts Trimethylolpropane trimethacrylate 18 parts Takenate D-11ON (75% by weight ethyl acetate solution) (manufactured by Takeda Pharmaceutical Co., Ltd. (trade name)) 24 mix the parts,
The resulting emulsion was added to an aqueous solution consisting of 63 parts of an 8% by weight aqueous solution of polyvinyl alcohol (Kuraray PVA-217E) and 100 parts of distilled water, and then emulsified and dispersed at 20°C to obtain an emulsion with an average particle size of 2μ. was stirred at 40°C for 3 hours.

After cooling this liquid to 20°C, Amberlite IR-
120B (manufactured by Rohm and Haas (product name))
Add 0 cc and stir for 1 hour, then filter to obtain capsule liquid A.
I got it.

(Emulsified dispersion of coupler A) 14 parts CH of the following coupler.

CH2NHCOCH2Co-C-CH3CH.

4 parts Triphenylguanidine (base) Color development aid 6 parts Tricresyl phosphate Ethyl acetate 10 parts 20 parts The above mixture was dissolved in a 4% by weight aqueous solution of polyvinyl alcohol 17 parts
0 parts, mixed and emulsified at 20°C to obtain an average particle size of 1.
A 5μ emulsified dispersion was obtained.

L-1 of Capsule' B As an electron-donating dye precursor, zHs 1-phenyl-1-xylylethane 55 parts Ethyl acetate 55 parts Sumithorpe 2
2 parts of 00 (ultraviolet absorber manufactured by Sumitomo Chemical ■) and 60 parts of Takene 1-D-11ON (manufactured by Takeda Pharmaceutical Company Limited (trade name)) were mixed together, and 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol was added.
2 parts and 40 parts of distilled water.
The mixture was emulsified and dispersed at 0°C to obtain an emulsified dispersion having an average particle size of 1 μm.

Next, the obtained emulsion was stirred at 40°C for 3 hours to obtain capsule liquid B.

゛ 8 parts of color developer (a), 4 parts of (b) and 30 parts of (C) represented by the following structural formula of A are mixed with 2 parts of 1-phenyl-1-xylylethane.
．． 0 parts, dibutyl phthalate 6.0 g and ethyl acetate 30
It was dissolved in parts. The obtained developer solution was mixed and emulsified into an aqueous solution of 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol, 151 parts of water, and 0.5 parts of sodium dodecylbenzenesulfonate to form an emulsified dispersion with a particle size of 0.5μ. I got something.

Color developer (a) Color developer (C) CH.

C,H.

The following compounds (CIBA
Pergascript Red l-6-8)Cs
20g each of bisphenol A as a color developer and β-naphthylbenzyl ether as a sensitizer were dispersed with 100g of a 5% polyvinyl alcohol (PVA-105 manufactured by Kuraray) aqueous solution in a ball mill day and night, and the volume average particle size was determined. The thickness was set to 3 μm or less.

Calcium carbonate (Unjbur70: manufactured by Shiraishi Kogyo ■) was used as the pigment, and 80g was mixed with 0% sodium hexametaphosphate.
．． It was used after being dispersed with 160 g of a 5% aqueous solution using a homogenizer. Each dispersion prepared as above was mixed with 2-
Anilino-3-methyl-N-methyl-cyclohexylaminofluorane fraction i solution 5g1 bisphenol A fraction hil
Og.

A heat-sensitive dispersion A was obtained by mixing 15 g of the β-naphthylbenzyl ether dispersion.

Kari 11 Tatsuyaji's next work Silica-modified polyvinyl alcohol (Kuraray ■WPVA
R2105) 10% by weight liquid 10 parts Colloidal silica (Snowtex 30 manufactured by Nichichi Kagaku ■) 30 parts heavy stationary solution 5 parts Zinc stearate (Hydrin 2-7 manufactured by Middle East Yushi ■) 30% by weight liquid
0.42 parts Paraffin wax (Hydrin P-7 manufactured by Middle East Yushi ■) 30% by weight liquid 0.
42 parts were mixed to obtain a protective layer liquid A for a transparent protective layer.

Silica-modified polyvinyl alcohol manufactured by m-tandan (PVA manufactured by Kuraray)
R2105) 10% by weight aqueous solution 15 parts Colloidal silica (Snowtex 30 manufactured by Nichichi Kagaku ■) 30% by weight aqueous solution 8.5 parts Zinc stearate (Hydrin Z-7 manufactured by Middle East Yushi ■) 30% by weight aqueous solution
0.42 parts Paraffin wax (Cellosol D-130 manufactured by Tokyo Yushi Corporation) 22% by weight aqueous solution 0.5
4-part titanium oxide (Tiebake A-100 manufactured by Ishihara Sangyo ■)
) 1.9 parts of a 33% by weight aqueous dispersion were mixed to obtain a protective layer liquid B for maintaining opacity.

Record 2, Part 2, ■ Preparation: After corona discharge treatment was applied to both sides of a biaxially stretched polyethylene terephthalate film with a thickness of 95a, a mixed solution of 5.0 parts of capsule liquid B and 10.0 parts of color developer dispersion liquid A was dried and applied. It was applied in an amount of 6 g/rrf.

Next, as an intermediate layer, a 1% aqueous solution of sodium alginate (Snow Algin SH manufactured by Fuji Chemical ■) was applied in a dry coating amount of 1 g7.
It was coated so that it became ``m''.

Additionally, 6 parts of capsule liquid A and 5.5 parts of coupler/base dispersion liquid.
0.1 part of calcium chloride was added to the mixed solution of 1.0 parts, and the coating was applied so that the dry coating amount was 6 g/m'', and then the protective layer liquid A was applied so that the dry coating weight was 2 g/m''.

On the other side of the above coating layer, apply heat-sensitive dispersion liquid A to a dry coating amount of 6 g/m'', then apply protective layer liquid B to a dry coating weight of 2 g/m''. and obtained a record sheet.

The coating was performed using a wire bar and then dried in an open air at 50°C.

The obtained recording sheet was thermally printed with low energy from the transparent protective layer side (pressure of the thermal head was 13 V, printing time was 0 to 2.5 m5ec), and then Rifbee Super Dry 10
The diazo coloring layer was fixed by irradiation with light for 10 seconds using Type 0.

After that, thermal printing was performed with higher energy than the above printing energy (thermal head voltage 18V, printing time 2.5~
5ms e c).

The resulting image was a clear two-color print in which the low-energy print area was yellow and the high-energy print area was cyan.

Furthermore, thermal printing was performed with low energy from the opaque protective layer side (thermal head voltage 13V, printing time 0-5ms e c
) However, it developed a magenta color.

When the obtained image was observed from the transparent protective layer side, a clear full-color image was obtained.

Comparative Example A recording sheet was obtained in exactly the same manner as in the example except that a 30 μm thick biaxially stretched polyethylene terephthalate film was used as the 1° support.

When the obtained recording sheet was colored in exactly the same manner as in the example, it was not possible to obtain an unbalanced image in which cyan and magenta were mixed.

Furthermore, misalignment of three colors was observed.

Comparative Example 2゜2.1 of 1-phenyl-1-xylylethane and 6.0 of dibutyl phthalate used in preparing color developer dispersion A in Example
FIG. 2 is a cross-sectional configuration diagram of a heat-sensitive recording material according to the present invention.

FIG. 4 is a diagram showing the state of color development after the heat-sensitive recording material of FIG. 3 is subjected to thermal printing and exposure.

1... Transparent support 2... Opaque magenta heat-sensitive layer 3... Transparent cyan heat-sensitive layer 4... Transparent protective layer 5... Opaque protective layer 6... Transparent Using the yellow heat-sensitive layer patent applicant Fuji Photo Film Co., Ltd.,
The emulsion of the color developer dispersion was unstable, which was inconvenient for obtaining a transparent heat-sensitive layer.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram of a heat-sensitive recording material according to the present invention. FIG. 2 is a diagram showing the state of color development after the heat-sensitive recording material shown in FIG. 1 is heated and printed.

Claims (1)

[Claims] In a multicolor heat-sensitive recording material in which one or more color-forming unit layers capable of developing a hue different from any of the color-forming hues are provided on each side of a transparent support, an opaque color-forming unit layer is provided on the outermost color-forming unit layer on one side By laminating a protective layer and laminating a transparent protective layer on the coloring unit layer provided on the opposite side, each of the coloring unit layers is layered so that a multicolored reflective image can be seen from the side of the transparent protective layer. Among them, at least all the coloring unit layers except for the coloring unit layer immediately below the opaque protective layer are substantially transparent heat-sensitive layers having a haze of 60% or less, and the thickness of the transparent support is 40 μm or more. A multicolor heat-sensitive recording material, wherein the transparent heat-sensitive layer has one or more heat-sensitive layers whose color forming system is a combination of a diazo compound and a coupler, and the heat-sensitive layer contains at least either the diazo compound or the coupler. It is a heat-sensitive layer formed by coating and drying a coating solution containing an emulsified dispersion as one component of the coloring system, which is dissolved in an ester-based organic solvent that is sparingly soluble or insoluble in water and then emulsified and dispersed in the aqueous phase. A multicolor heat-sensitive recording material with special features.