JPS6345084A - Multicolor thermal recording material - Google Patents

Abstract

PURPOSE:To contrive higher hue properties, color separation properties and preservability of images, by emulsifying or dispersing capsules containing a specified color forming component therein and a coupler or a color developer in an organic solvent difficulty soluble in water, and applying the resultant emulsion or dispersion to both sides of a transparent base. CONSTITUTION:A multicolor thermal recording material comprises a transparent base provided with a transparent undercoat layer on each side thereof and provided further with at least one thermal color forming layer and at least one protective layer on each side thereof. Microcapsules containing a diazo compound or a basic dye precursor therein are dissolved, together with a coupler or a color developer, in an organic solvent difficulty soluble in water or insoluble in water, followed by emulsifying or dispersing, and the resultant emulsion or dispersion is applied to provide a color forming unit layer. For example, where a cyan color forming layer and a magenta color forming layer are provided respectively on both sides of the transparent base, when thermal recording of images is conducted on each side by using a heat pen or a thermal head, a cyan color and a magenta color are independently developed respectively on both side of the base with substantially the same applied energy. As a result, since the base is transparent, cyan, cyan + magenta (blue) and magenta colors can be developed (as seen from one side of the base) with favorable color separation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a heat-sensitive recording material that develops multiple colors.

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

(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.

An inkjet method and a thermal transfer method are being considered as methods for this purpose. However, since this inkjet method uses a thin nozzle to inject the colorant and then ejects the ink, the nozzle is easily clogged with the colorant and other contents (and has major drawbacks such as a lack of reliability in recording). In addition, the thermal transfer method heats and melts the ink on the ink sheet in the form of an image and transfers it to paper, so for example, in order to obtain a four-color image, it is necessary to use four ink sheets. This method requires the use of a large amount of ink sheets, which is uneconomical.Also, in the case of an inkjet method, the user must always be careful not to run out of ink.
In the case of the thermal transfer method, it is necessary to purchase ink sheets from 6 companies to ensure there is no shortage of ink sheets. That is, both methods force the user to perform complicated management.

On the other hand, the thermal recording method does not require the above-mentioned strict management and has high recording reliability, so if a multicolor recording material is realized using this method, it will be easy to use without the drawbacks of the conventional methods. Become. However, in order to produce multiple colors, it is necessary to incorporate a number of coloring mechanisms corresponding to the number of colors on the same support and to control each coloring mechanism to make it work, so many efforts have been made in the past. However, the color development was not satisfactory in terms of hue and color separation.

For example, as one of the conventional methods,
No. 9, No. 52-11231, JP-A-54-88135
As described in No. 1, No. 55-133991, and No. 55-133992, a plurality of color forming units are simply added one after another as the printing heating energy increases, and the colors are mixed and the hue changes while becoming muddy (there are other methods. As a method, for example, Japanese Patent Publication No. 50-17868, No. 51-5791, No. 57
No.-14318, No. 57-14319, JP-A-55-
As shown in No. 161688, there is a color-erasing mechanism in which when a color-forming unit with a higher thermal response temperature develops color, a color-erasing agent acts at the same time to erase the color-forming unit that develops color at a lower temperature.

(Problems to be Solved by the Invention) However, in all of these methods, not only are there only a small number of color hues that can be realized, but also there is turbidity due to bleeding and color mixing, so it is difficult to have sufficient functionality as a color hard copy. It is difficult to say, especially as a color hard copy, the fact that the number of color hues that can be developed is small in principle is a fatal drawback.

The following points can be cited as one of the major reasons why this drawback could not be overcome in the past. That is, for example, if you want to increase the number of coloring hues, you can simply increase the number of fractions of applied heating energy and widen the energy difference between them, so that the corresponding heat-sensitive coloring layers can be formed on the same support. It is possible to design a heat-sensitive recording material having multiple heat-sensitive recording materials on the top, but in reality, if the applied heating energy is expanded to a lower @ range than before, there will be problems in terms of storage stability (so-called fog) of the recording material itself. On the other hand, if the applied heating energy is extended to a high range, new serious problems will arise in terms of image scorching, poor print runnability due to fusion (e.g. sticking), and shortened thermal head life. .

Therefore, in the past, the maximum allowable fraction of the applied heating energy was actually about 2 fractions in order to satisfy the color separation property.

On the other hand, as a support for heat-sensitive recording materials, an opaque support such as paper or synthetic paper is usually used. This is due to the purpose of simply reading a colored image as a reflected image from one side.

Examples of conventional heat-sensitive recording materials provided on substantially transparent supports include Japanese Patent Publication No. 40-20151 and Japanese Patent Application No. 60-6
There is No. 8875 and Japanese Patent Application No. 184483/1983.
These methods have been developed for the purpose of obtaining a high-contrast image or a high-quality image with excellent gloss by viewing a thermally recorded image from the transparent support side. Further, as an example in which the heat-sensitive coloring layer 1 is provided on both sides of a support, Japanese Patent Application Laid-Open No. 57-208298 has been proposed. The purpose of this is to print and record on both sides of an opaque support, thereby reducing losses in terms of cost and storage space for printed copies. It did not make any special contribution to the deficiencies.

Furthermore, the invention of providing two or more color images by providing heat-sensitive recording layers with different color hues on both sides of a transparent support is disclosed in JP-A-49-114431 and JP-A-50-36.
No. 40 and Japanese Patent Application Laid-Open No. 60-4092.

However, since the heat-sensitive color forming layer is simply a mixture of a color forming component and a color developing component dispersed in a solid state, the color forming layer itself essentially becomes an opaque layer due to light scattering. It is not possible to obtain a multicolor image with clear color separation.

In addition, in the above-mentioned Japanese Patent Application Laid-open No. 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 heat-sensitive coloring layer, but in this case, the coloring of each component is This easily occurs even before printing, resulting in so-called fog. Therefore, in any case, the above-mentioned known techniques have a small number of possible color divisions, and are essentially unsatisfactory as multicolor recording materials.

The inventors of the present invention, as a result of intensive studies to solve the drawbacks of the conventional technology, have found that by providing a substantially transparent color-forming layer on both sides of a transparent support that develops colors in different hues, the present inventors can achieve better heat sensitivity than ever before. It was discovered that colored images can be obtained, and the present invention was achieved.

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

An object of the present invention is to provide a method for forming a good multicolor image using a heat-sensitive recording method.

(Means for Solving the Problems) The above-mentioned object of the present invention is to provide a multicolor heat-sensitive recording material in which at least one color-forming unit layer capable of developing different hues is provided on both sides of a transparent support. At least one of the color-forming unit layers is substantially transparent, and a combination of a diazo compound and a coupler or a combination of a basic dye precursor and a color developer contained as a color-forming component in the transparent color-forming unit layer, and the combination thereof. (Among the additives, at least a diazo compound or a basic dye precursor is encapsulated in microcapsules, and a coupler or color developer coexisting with the microcapsules is dissolved in an organic solvent that is sparingly soluble or insoluble in water.) This was achieved with a multicolor heat-sensitive recording material characterized by being coated after emulsification and dispersion.

A more desirable embodiment of the multicolor heat-sensitive recording material (hereinafter abbreviated as heat-sensitive material) of the present invention uses a transparent support having a transparent undercoat layer on both surfaces, and further includes one or more heat-sensitive layers (
That is, it has a structure consisting of a plurality of heat-sensitive layers that develop colors in at least two or more different hues as a whole, and a protective layer.

(Function) A method for easily obtaining a good multicolor image using the heat-sensitive material of the present invention will be explained 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 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.

In this case, the support is substantially transparent, so when viewed from one side the result is cyan, cyan + magenta (blue).
The color development of magenta and magenta can be realized with good color separation (see FIG. 2).

Although the case where the two coloring units of cyan and magenta are used has been described above, the case where the coloring unit is composed of three coloring units of cyan, magenta, and yellow is basically exactly the same. That is,
For example, a heat-sensitive layer that develops a yellow color on one side of a 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 develop the three colors independently, it is desirable to employ a system of a coupling color development reaction of a diazo compound and a light fixing reaction as disclosed in JP-A-61-40192. That is, first, the yellow layer and the cyan 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 selectively photodecomposes only yellow and cyan diazo. Next, by thermally recording the inner magenta 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 magenta layer does not place an excessive burden on the recording material and mounting surface, and therefore has great practical value. As a result, when viewed from one side of the transparent support, cyan, magenta, yellow, cyan + magenta (brood), cyan yellow (green), cyan magenta + yellow (black), which was difficult to see in conventional thermal recording, can be seen. A total of seven basic colors can be achieved with good color distribution (see Figure 4).The yellow coloring layer is separated by a support, so all of the above colors can be reproduced without fixing. Furthermore, those skilled in the art will 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. Can be done.

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 according to the present invention is a component that causes a coloring reaction based on contact with a substance by heating, and specifically, an acidic These are 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 the property of donating electrons or accepting protons such as acids to develop color, and is usually approximately colorless, although it is not particularly limited. Compounds having a partial skeleton such as , lactone, lactam, sultone, spiropyran, ester, amide, etc., and whose partial skeleton is ring-opened or cleaved upon contact with a color developer are used. Specifically, crystal bioleft lactone, benzoylleucomethylene blue, malachite green lactone, rhodamine B lactam, 1.3.3-trimethyl-6°-ethyl-8
'-Butoxyindolinobenzospiropyran and the like.

Acidic substances such as phenol compounds, organic acids or metal salts thereof, and oxybenzoic acid esters are used as color developers for these color formers.

The preferable melting point of the color developer is 50° C. to 250° C., and phenols and organic acids having a melting point of 60° C. to 200° C. and which are sparingly soluble in water are particularly desirable.

Specific examples of these color developers are disclosed in Japanese Patent Application No. 1983-132, for example.
No. 990.

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 campling component, which will be described later. When exposed to light, it decomposes and no longer has any coloring ability even when the coupling component acts.The hue in this coloring system is due to the diazo dye produced by the reaction of the diazo compound and the camping component. Therefore, as is well known, the color hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupling component; Any desired color hue can be obtained.For this reason, one layer may contain various diazo compounds, and one type of camping component or other additives may be incorporated in the interlayer. In this case, each unit coloring group is composed of a different diazo compound, a common camping component, and other additives. However, there are combinations in which the same diazo and other additives are incorporated into each layer.In this case, each unit coloring group is composed of a different coupling component and a common diazo compound and additive. In any case, each unit color forming group is composed of one or more diazo compounds combined so as to have different color hues, one or more coupling components, and other additives.

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. This will be explained using salt as an example.

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 20Qnm to 700nm, depending on their chemical structure.
It is known that it can change up to m. (“Photolysis 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, if a diazonium salt is used as a photodegradable compound, it will be decomposed by light of a specific wavelength depending on its chemical structure, and if the chemical structure of the diazonium salt is changed, it will be able to couple with the same coupling component. The hue of the dye also changes when reacted, and it can be preferably used in the present invention.

A diazonium salt is a compound represented by the general formula ArNz+X-. (In the formula, Ar represents a substituted or unsubstituted aromatic moiety, N2+ represents a diazonium group,
X- represents an acid anion. ) In the present invention, it is one of the desirable embodiments to use diazonium compounds having different photodecomposition wavelengths, but as compounds having photodecomposition wavelengths around 400 nm, 4-diazo-1-dimethylaminobenzene, 4-diazo -1-diethylaminobenzene, 4
-Diazo-1-diethylaminobenzene, 4-diazo-
1-methylbenzylaminobenzene, 4-diazo-1
-dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamine-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-1,4-methoxybenzoylamino-2,5-
Examples include jetoxybenzene, and 300 to 3
Compounds having a photolysis wavelength of 70 nm include 1-diazo-4-(N,N-dioctylcarbamoyl)benzene, 1-diazo-2-octadecyloxybenzene, 1
-Diazo-4-(4-tert-octylphenoxy)
Benzene, 1-diazo-4-(2,4-tert-
amylphenoxy)benzene, 1-diazo-2(4te
rt-octylphenoxy)benzene, 1-diazo-5
-chloro-2-(4-tert-octylphenoxy)
Examples include benzene, 1-diazo-2,5-bis-octadecyloxybenzene, 1-diazo-2,4-bis-octadecyloxybenzene, 1-diazo-4-(N-octylteraroylamino)benzene, etc. Aromatic diazonium compounds represented by 0 or more examples that can be
By arbitrarily changing the substituents, the photolysis wavelength can be changed widely.

Specific examples of acid anions include CnF2n+IC0O-
(n represents 3 to 9), CmF2m+1S○3-(
m represents 2 to 8), (CA'F2g+1so2)2
0H- (7! represents 1 to 18), C13H27CO
Examples include NH*/old(CH3)3ki/di\l11*/PF5-.

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

♂C2H5 C2H5 (?Cl5H17 The diazosulfonate compound that can be used in the present invention is a compound represented by the general formula % Formula % where R1 is an alkali metal or an ammonium compound, R2, R3, R5 and R5 are Hydrogen, a halogen, an alkyl group, or a haalkoxyl group, and R4 is hydrogen, a halogen, an alkyl group, an amide group, a benzoylamido group, a morpholino group, a trimercapto group, or a 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, etc., or 4-(N-ethyl, N-benzyl amino), 4-(N
, N-dimethylamino), 4-(N,N-diethylamino), 4-(N,N-diethylamino)-3-chlor, 4-virodinino-3-chlor, 4-morpholino-2
-methoxy, 4-(4'-methoxybenzoylamino)-2,5-dibutoxy, 4-(4'-1-rimercapto)-2,5-dimethoxy, and other benzenediazosulfonate salts. . 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. Diazoamino compounds include compounds in which a diazo group is coupled with dicyandiamide, sarcosine, methyltaurine, N-ethylanthranic acid-5-sulfonic acid, monoethanolamine, jetanolamine, guanidine, etc.

The color developer for the diazo compound used in the present invention is a coupling component that couples with the diazo compound (diazonium salt) to form a dye.

Specific examples include 2-hydroxy-3-naphthoic acid anilide, resorcinol, and the patent application filed in 1983.
Examples include those described in No. 0-287485.

Furthermore, by using two or more of these compulsions 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 water-releasable or water-insoluble basic substance or a substance that generates an alkali upon heating is used. Examples of these are inorganic and organic ammonium salts, organic amines, 7-amides, ureas and 1,000 ureas and their derivatives, thiazoles, virols, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidacillins. , triazoles, morpholines, piperidines, amidines, formazines, and lysines. 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 by preventing contact between the color forming agent and the color developer at room temperature (capri prevention), and from the viewpoint of color development with the desired impression heating energy. Some of the components are encapsulated and used from the viewpoint of controlling color development sensitivity.

A preferable microcapsule is one that prevents contact between substances inside and outside the capsule at room temperature due to the substance isolation effect of the microcapsule wall, and whose permeability to substances increases only when heated above a certain temperature.

This phenomenon is a new technology previously discovered by the present inventors, and by appropriately selecting the capsule wall material, capsule core material, and additives, the permeation start temperature can be freely controlled. The transmission start temperature in this case corresponds to the glass transition temperature of the capsule wall (eg, Japanese Patent Application Laid-Open No. 9-91438, Japanese Patent Application No. 190886-1986, Japanese Patent Application No. 99490-1987, etc.).

To control the glass transition temperature specific to the capsule wall, the f! It is necessary to change the class. 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 polymeric material is formed or an actant 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 an organic solvent that dissolves the color developer described below is used, it has excellent solubility in the color former, increases color density and color development speed during thermal printing, and reduces capri. This is preferable because it can be done.

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

The amount of coupling component is 0.0% per 1 part by weight of the diazo compound.
It is preferable to use 1 to 10 parts by weight, and the basic substance to be used in a proportion of 0.1 to 20 parts by weight. On the other hand, for 1 part by weight of the basic dye precursor, 0.3 to 160 parts by weight of the color developer,
It is preferable to use 0.3 to 80 parts by weight.

In the present invention, the size of the microcapsules is preferably 2 μm or less, particularly preferably 1 μm or less, as measured by the measurement method described in JP-A No. 60-214990.

The preferred microcapsules produced as described above are not ruptured by heat or pressure as is used in conventional recording materials (the core of the microcapsules and the reactive substances contained on the outside of the microcapsules are Can react by penetrating walls.

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

The color development aid that can be used in the present invention is a substance that increases the color density during thermal printing or lowers the minimum color development temperature, such as a camping component, a basic substance, a color former, a color developer, or a diazo Lowering the melting point of compounds, etc.
This is to create a situation where the diazo, basic substance, coupling component, color former, and color developer are more likely to react by lowering the softening point of the capsule wall.

Coloring aids include phenolic compounds, alcoholic compounds, amide compounds, sulbonamide compounds, etc.
Specific examples include p-tert-octylphenol, p-benzyloxyphenol, p-,i-xybenzoic acid phenyl, benzyl carbanylate, phenethyl carbanylate, hydroquinone dihydroxyethyl ether,
Compounds such as xylylene diol, N-hydroxyethyl-methanesulfonic 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, after dissolving a basic dye precursor or a color developer for a diazo compound as a coloring agent in an organic solvent that is sparingly soluble or insoluble in water, 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 emulsified dispersion.

The organic solvent for dissolving the color developer can be appropriately selected from among high-boiling point oils, but in particular oils that have two or more benzene rings and the number of heteroatoms is less than a specified number, which are known as pressure-sensitive oils. Preferably, such oils include compounds represented by the following general formulas (1) to (rV), triallylmethane (e.g., tritolylmethane, tolyldiphenylmethane), terphenyl compounds (e.g.,
terphenyl), alkyl compounds (e.g. terphenyl), alkylated diphenyl ethers (e.g. propyl diphenyl ether), hydrogenated terphenyl (e.g.
In addition to diphenyl ether (hexahydroterphenyl), it is preferable to use a maleic acid ester represented by the general formula (IV) from the viewpoint of emulsion stability of the emulsified dispersion of the color developer.

2 \ / In the formula, R1 is hydrogen or an alkyl group having 1 to 18 carbon atoms, R
2 represents an alkyl group having 1 to 18 carbon atoms. pl,
ql represents an integer from 1 to 4, and the number of alkyl groups is 4 or less.

In addition, the alkyl group of R1, R, and 2 is preferably an alkyl group having 1 to 8 carbon atoms.

(n) In the formula, R3 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 is 1
Or represents 2.

p2 and q2 represent integers from 1 to 4. In the case of n-1, the total number of alkyl groups is within 4, and when nx 2, the total number of alkyl groups is within 6.゛(I[I) In the formula, R5 and R6 represent a hydrogen atom or the same or different alkyl groups having 1 to 18 carbon atoms.

m represents an integer of 1 to 13, p3 and q3 represent integers of 1 to 3, and the total number of alkyl groups is 3 or less.

In addition, the alkyl group of R5 and R6 is particularly preferably an alkyl group having 2 to 4 carbon atoms.

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

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

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

(TV) In the formula, R is a C1 to C1δ alkyl group, but especially C1 to C1δ alkyl group.
A 1-C5 alkyl group is preferred.

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, bovinyl 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 gelicol (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 of ordinary methods 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 40% or less. More preferably 0.1 to 5μ
is within the range of

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 0.
It is 1 to 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.

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

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

In the present invention, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid, etc. can be added to the pond made of the above material as an acid stabilizer.

Further, the heat-sensitive material of the present invention can be viewed as a transmitted image or a reflected image from one side of the transparent support, but especially in the latter case, if the back side of the background part is visible, the image will not be clear. , 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 either case, it is effective to perform this on the outermost layer on the reflective side from the side where the recorded image is viewed.

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.

Furthermore, when the outermost coloring layer itself is made opaque by using a coloring component other than diazo, a color developer component, etc. used in the present invention, it is preferable to use a solid dispersion using a sand mill or the like. , each separately dispersed in a water-soluble polymer solution. Preferred water-soluble polymers include water-soluble polymers used when making microcapsules.

At this time, the concentration of water-soluble polymer is 2 to 30% by weight,
Coloring components other than diazo and color developer are added to this water-soluble polymer solution in an amount of 5 to 40% by weight, respectively.

The dispersed particle size is preferably 10 microns or less.

In addition, the coating amount of the heat-sensitive layer is 3 g/rd to 20 g/i, especially 5
It is preferable that it is between g/m and 15g/rrf. Sufficient sensitivity cannot be obtained below 3g1rd, and 20g/rrf or less
Even if the coating is applied for more than 1 time, no improvement in quality will be observed, which will be disadvantageous in terms of cost.

At least one of the heat-sensitive layers in the present invention must be substantially transparent in order to improve color separation. Substantially transparent here means haze (%) (Nippon Seimitsu Kogyo ■
40% (measured using an integrating sphere method HTR meter)
Must be below. Preferably it is 30% or less, more preferably 20% or less. However, the transparency of an actual heat-sensitive layer test sample is greatly influenced by light scattering due to minute irregularities on the surface of the heat-sensitive layer. Therefore, when measuring the inherent transparency of the heat-sensitive layer, which is a problem in the present invention, that is, the transparency inside the heat-sensitive layer, a simple method is to attach a transparent adhesive tape on top of the heat-sensitive layer, and then Evaluation is made using the measured value with almost all scattering removed.

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

The silicon-modified polyvinyl alcohol used in the present invention is
There is no particular limitation as long as the silicon atom is contained in the molecule, but usually the silicon atom 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 those having reactive substituents.

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 B fine 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 OpH value of the colloidal solution in this case is about 4 to about 1
0 is preferably used.

When the above-mentioned 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 above-mentioned transparent adhesive tape is applied, and surprisingly, the transparency of the protective layer is very good. In addition, 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 improves, and the transparency of the entire heat-sensitive material is improved. When provided as an intermediate layer between the eyebrows, it can additionally serve to prevent unnecessary color mixing between the eyebrows.

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 instead.

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, and styrene-maleic anhydride. Water-soluble polymers such as acid copolymer hydrolyzate, styrene-maleic anhydride copolymer half ester hydrolyzate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide derivatives, polyvinylpyrrolidone, sodium polystyrene sulfonate, sodium alginate, etc. and water-insoluble polymers such as styrene-butadiene rubber latex, acrylonitrile-brassene rubber latex, methyl acrylate-butadiene rubber latex, and polyvinyl acetate emulsion. 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, soap, wax, cross-linking agents, etc. are added to the protective layer for the purpose of improving matching with the thermal head during thermal printing and improving the water resistance of the protective layer.

Pigments include zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, Rouseki, kaolin, aluminum hydroxide, amorphous silica, etc., and the amount of these added is 0.05 to 0.05 of the total N amount of the polymer. 2 times, particularly preferably 0. The amount is 1 to 0.5 times. If the amount is less than twice the amount of O,OS, it is ineffective in improving the matching property with the head, and if the amount is more than twice the amount, 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, calicylam stearate, aluminum stearate, etc., and the proportion thereof is 0.5 to 20% by weight, preferably 1 to 10% by weight of the total weight of the protective layer. added in quantity. Waxes include emulsions such as paraffin wax, microcrystalline wax, carnauba wax, methylolstearamide, polyethylene wax, and silicone, and the amount of wax is 0.5 to 40 M% of the total weight of the protective layer.
It is preferably added in a proportion of 1 to 20% by weight.

Further, in order to uniformly form a protective layer on the heat-sensitive 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.

Furthermore, a surfactant, a polymer electrolyte, etc. may be 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/at, more preferably 1 g to 3 g/n.

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.

The thickness of the transparent support used is 20 to 200 .mu.m, particularly preferably 50 to 100 .mu.m.

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, but materials for the undercoat layer include gelatin, synthetic polymer latex,
Nitrocellulose and the like are used. The coating amount of the undercoat layer is 0
．． It is preferably in the range of 1 g/m to 2.0 g/m, particularly 0.2 g/m to 1. A range of Og/- is preferred.

0.1g/rr? If it is less, the adhesion between the support and the heat-sensitive layer will not be sufficient; Og/n? Even if it is increased above, the adhesive force between the support and the heat-sensitive layer has reached saturation, which is disadvantageous in terms of cost.

The undercoat layer becomes sensitive if the undercoat layer swells due to the water contained in the heat-sensitive layer when the heat-sensitive layer is applied thereon. Since the image quality of H may deteriorate, it is desirable to harden using a hardening agent.

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-triacryloyl-
Active vinyl compounds such as hexahydro-3-triazine, 1,3.5-)rivinylsulfonyl-hexahydro-5-)lyazine.

■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 bis(2-chloroethylcarbamyl)piperazine.

■Bis(2,3-epoxypropyl)methylpropylammonium p-toluenesulfonate, 1,4-bis(2',3°-epoxypropyloxy)butane,
1,3.5-triglycidyl isocyanurate, 1.3
-Epoxy compounds such as diglycidyl-5-(T-acetoxy-β-oxypropyl)isocyanurate.

■2.4.6-) diethylene-3-triazine, 1.6
-hexamethylene-N,N'-bisethyleneurea,
Ethylenimino compounds such as bis-β-ethyleneiminoethylthioether.

■l, 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/perchloric acid m, 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-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'-phthaloyldioxydisuccinimide.

Isocyanates such as 0 toluene-2,4-diisocyanate and 1°6-1 methylene diisocyanate.

The amount of these hardeners added is based on the weight of the base coat material.
A suitable addition amount can be selected from a 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 and 9%, the degree of curing will be insufficient no matter how long it is left, and the undercoat layer will be damaged when applying the heat-sensitive layer! 11
Unfortunately, if the amount is more than 3.0% by weight, the degree of curing will progress too much, and the adhesion between the undercoat layer and the support will deteriorate, and the undercoat layer will become film-like and hard to adhere to the support. It has the disadvantage of more peeling.

Depending on the curing agent used, if necessary, the pH of the solution may be made alkaline (1'J) by adding caustic soda, etc.
Alternatively, the pH of the liquid can be made acidic using citric acid or the like.

It is also possible to add an antifoaming agent to eliminate the foam that occurs during application, or to add an activator to improve liquid leveling (and prevent the formation of streaks). It is.

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, Same!
@3. 590. The corona discharge treatment described in No. 107 and the like is most preferably used.

The coating liquid according to the present invention can be applied by generally (known coating methods,
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, U.S. Pat.
No. 2,941.898, and No. 3゜526.
No. 528 Mei HJ book, “Coating Engineering” 2 by Yuji Harasaki
It is also possible to apply the coating simultaneously in two or more layers using the method described in p. .

Pigment dispersants, thickeners, flow modifiers, antifoaming agents, foam inhibitors, 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. There is nothing wrong with that.

The heat-sensitive material of the present invention can be used as a printer sheet for facsimiles and electronic computers that require high-speed recording. In this case, unlike normal facsimile machines and printers, it is desirable to use a device with so-called double-sided thermal heads that can perform Vf thermal recording on both sides at the same time. It is also possible to record heat on the other side. Further, when a diazo compound is used as a color-forming component, it is especially advantageous to provide an exposure zone for photolysis in order to improve the storage stability of images and to make them multicolored.

There are roughly two types of methods for arranging print heads and exposure zones. One is to irradiate light for photolysis after printing once, and before and after this irradiation, the recording material is fed 83&
By turning the recording material horizontally, the recording material returns to the printing standby state so that it can print again at the place that has been printed once, and then prints again, irradiates light again, and returns the recording material to its original position. One is the multi-head scan method, and the other is the so-called multi-head single scan method, which has as many recording heads as the number of colors you want to record and has a light irradiation zone between them. The thermal energy applied to the head may be changed as necessary. Also, various light sources that emit light at the desired wavelength can be used as the light source for photolysis. Various light sources can be used, for example, various fluorescent lamps, xenon lamps, xenon flash lamps, mercury lamps of various pressures, copying flashes, strobes, and the like. 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.

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, the present invention allows the obtained image to be either a transmission image or a reflection image, and opens the way to natural color image formation by non-silver halide photography, which is of great significance.

(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."

Capsule A diazo compound C4HCl ・□Contest ・=Φ Tricresyl phosphate 6 parts Methylene chloride 12 parts Trimethylolpropane trimethacrylate 18 parts Takenate D-11ON (75% by weight ethyl acetate solution) (manufactured by Narita Pharmaceutical Co., Ltd. (product) 63 parts of an 8% by weight aqueous solution of polyvinyl alcohol and 1 part of distilled water.
After adding it to an aqueous solution consisting of 0.00 parts, it was emulsified and dispersed at 20°C to obtain an emulsion with an average particle size of 2μ.Next, the obtained emulsion was continuously stirred at 40°C for 3 hours.

After cooling this liquid to 20°C, Amberlite IR-1
100 cc of 20B (Rohm & Haas I!1 (trade name)) was added, stirred for 1 hour, and then filtered to obtain capsule liquid A.

Kapu-’A’s “ 1. 170 parts of 4% by weight aqueous solution of polyvinyl alcohol ■.

Coupler 14 parts triphenylguanidine (base) 6 parts coloring aid = fist Φ = 14 parts tricresyl phosphin) 10 flS ethyl acetate 20 parts In I ■
'GH was added and emulsified and dispersed at 20°C to obtain an emulsified dispersion.

Kaboo-'B's Coupler/Base Dispersion A coupler, base, and polyvinyl alcohol were mixed in the same composition ratio as in the dispersion A, and dispersed using a Dyno Mill (manufactured by Willie A. Bacohuen AG (trade name)). A dispersion liquid having an average particle size of 3 μm was obtained.

A's.

As a color development aid, 138 parts of 4% polyvinyl alcohol by weight and 1fi of water was mixed, and Dynomil (Willy A. Bacofen A.
G-sha! ! 1 (product name)) to obtain an average particle size of 3μ.
A dispersion was obtained.

Capsule B - Basic colorless dye (Blue 200 manufactured by Yamada Chemical) 1
-Phenyl-1-xylylethane 55 parts Methylene chloride 55 parts Sumisorb 20
0 (Ultraviolet absorber made by Sumitomo Kagaku ■) 2 parts Tagene) D-11ON (manufactured by Narita Pharmaceutical Co., Ltd. (trade name)) 60i11 ri, 100 RI of polyvinyl alcohol 8 volume aqueous solution (and Nibaru water) After addition into water iS/& consisting of 40 parts, 2
Emulsification and dispersion was carried out at 0°C to obtain an emulsion with an average particle size of 1 μm.Next, the obtained emulsion was continued to be stirred at 40°C for 3 hours to obtain capsule liquid B.

The following compound (CIBA Perg) is used as a colorless dye made from a long base.
Using script Red l-C1-8) outside '14W, prepare capsule liquid Cfc in the same manner as capsule IB.
Obtained.

＼A- Color developer represented by the following structural formula (a) 8 parts, (b) 4 parts and (c) 308 (S was dissolved in 8 parts of 1-phenyl-1-xylylethane and 30 parts of ethyl acetate) .

of the resulting developer? Solution g was mixed and emulsified into an aqueous solution of 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol, 150 parts of water, and 0.5 part of sodium dodecylbenzenesulfonate to obtain an emulsified dispersion with a particle size of 0.5 μm.

Color developer (a) \ RiII 1 \ Final color developer (b) Color developer (c) 100 parts of polyvinyl alcohol (8% by weight) aqueous solution,
In 150 parts of water, color developer (a) 8 parts, (b) 4 parts, (c)
30 parts were added and dispersed with a Dyno Mill to obtain a dispersion having an average particle size of 3 μm.

Capsule liquid B s, os Color developer dispersion A (emulsified dispersion) 10.0 parts Distilled water
5.0 parts were stirred and mixed to obtain coating liquid A.

(21' 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 instead of developer dispersion A. I got it.

(Mazen of 3'B) 5.0 parts of capsule liquid C, 10.0 parts of color developer dispersion A (emulsified dispersion), and 5.0 parts of distilled water were stirred and mixed to prepare coating liquid B.

(Mazen of 4'B') For all the ponds in which 10.0 parts of color developer dispersion B (solid dispersion) was used instead of color developer dispersion A, coating liquid B was applied in the same manner as coating liquid B. I got ゛.

(5)-, t' C° Yellow) Capsule liquid A 4.9 parts Hydroquinone 5% by weight aqueous solution 0.2 parts Coupler/base dispersion A
3.7 parts were stirred and mixed to prepare a coating liquid C.

(2) "C' Yellow) Coupler/base dispersion B instead of 3.7 parts of coupler/base dispersion A
Coating liquid C'' was obtained in the same manner as coating liquid C, except that 3.7 parts of Coating agent dispersion A and 3.7 parts of coloring aid dispersion A were used.

A biaxially stretched polyethylene terephthalate film with a thickness of 75 μm was used as the transparent support for sheet A, and after corona treatment was applied to both sides, coating liquid A was applied to one side and coating liquid B was applied to the opposite side. The intermediate layer and coating solution C were sequentially coated, and the coating solutions A, B, and C were each dried at a rate of 12 g/rrf for 1 and 2 g'/rrf for the intermediate layer. 1 layer with the same composition as the layer on both sides at 2 g/rd
A recording sheet A was obtained.

11W (2nd; Silica-modified polyvinyl alcohol (PVA manufactured by Kuraray)
R2105) 1 part (solid content) Colloidal silica (Snowtefx 30 manufactured by Nissho Kagaku ■)
1.5 parts (solid content) Zinc stearate (Hydrin Z-7 manufactured by Tokyo Yushi ■)
0.02 parts (solid content) Paraffin wax (Hydrin P-7 manufactured by Tokyo Yushi Corporation) 0.02 parts (
Solid content) 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 of sheet B.

・Instead of coating liquids A, B, and C of C (C), apply coating liquids A'', B', and C, respectively.
Recording sheet C was obtained in the same manner as recording sheet A except that C' was used.

! I 1 sheet! Heavy liquids A, , A', B, B'', cXc' were each coated on the transparent support at a rate of 12 g/rr, and then the protective layer was provided at a rate of 2 g/rd, and the sheets were used as recording sheets) a, a', b, b', c, c'.

Example 1 Recording sheets A, B, C and transparency measurement sheets a, a
The haze (%) of each sample of ', b, b', c, and Co was measured using an integrating sphere HTR meter manufactured by Nihon Seimitsu Kogyo ■ (However, recording sheets A, B, and C were measured from the cyan coloring side. The results are shown in Table 1.

Table 1 Hey feeling (%) ゛ Daily record sheet a 16 Good a゛
80 Insufficient b 15 Good/ bo 82 Insufficient ~ c
17 Good ~ C' 81
- Recording sheet A 18
Good recording sheet B 75 Inadequate sheet C95\ This result shows that microcapsules containing a diazo compound or basic precursor as a core substance and a coupler or color developer are dissolved in a water-insoluble organic solvent and emulsified. When using a coating solution containing a dispersed emulsified dispersion,
This proves that overall good triangularity can be obtained.

Example 2 When several places on each side of recording sheet A were heated at 100°C for 1 second at random using a heat block, yellow and cyan colors appeared on both sides. Light irradiation for 10 seconds with 100 type (4
00 to 430 nm), and then heated for 1 second at 120° C. from the yellow coloring side using a heat block, and the lower layer developed a magenta color.

As described above (when printing at a low temperature before irradiation with light, both sides of the recording sheet develop yellow and cyan colors respectively, then by photodegrading the diazo compound (yellow coloring layer) by irradiation with light and printing at a somewhat high temperature, The same recording sheet was colored magenta.As a result, when this sheet was viewed from one side as a transmitted image, the colored image was cyan, magenta, yellow, blue (cyan + magenta), green (cyan + yellow), red (yellow). A clear color image of fluff (cyan + magenta) and fluff (cyan + magenta/yellow) without any unnecessary color mixture or color bleeding 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 reflected image from the cyan coloring side, the diazo layer portion on the opposite side that was substantially opaque By exhibiting a mouth-colored background after photofixing, a clear, reflective multicolor image without unnecessary color mixture or color blurring was obtained.

Comparative Example Recording sheet C was recorded in the same manner as recording sheet A, but it was inferior to recording sheets A and B in terms of color separation and sharpness because the transparency of each coloring layer was insufficient. The result is a multicolored image.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of the heat-sensitive material of the present invention in which a coloring layer is provided on both sides of the support. FIG. 2 is a sectional view showing an example of color development when thermal printing is performed on the heat-sensitive material shown in FIG. 1. FIG. FIG. 3 is a cross-sectional view of the heat-sensitive material of the present invention having three coloring layers. FIG. 4 is a sectional view showing the state of color development when thermal printing is performed on the heat-sensitive material of FIG. 3. FIG. In the figure, code 1 is green, 2 is yellow, 3 is red,
4 is a blue hue, 5 is a blue hue, 6 is a cyan hue, and 7 is a magenta hue. Patent applicant: Fuji Photo Film Co., Ltd. Agent
Patent Attorney Taki 1) Tsukehi 1 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1) A multicolor heat-sensitive recording material comprising one or more color-forming unit layers capable of developing different hues on each side of a transparent support, wherein at least one of the color-forming unit layers is substantially Among the combinations of a diazo compound and a coupler, the combination of a basic dye precursor and a color developer, and other additives, the transparent color-forming unit layer contains at least a diazo compound as a color-forming component. Alternatively, a basic dye precursor is encapsulated in microcapsules, and a coupler or color developer coexisting with the microcapsules is dissolved in an organic solvent that is sparingly soluble or insoluble in water, and applied after emulsification and dispersion. A multicolor heat-sensitive recording material characterized by: 2) The multicolor heat-sensitive recording material according to claim 1, wherein each transparent coloring unit layer has a haze of 40% or less. 3) The multicolor thermosensitive recording material according to claim 1 or 2, further comprising a protective layer laminated on the outermost color forming unit layer on both sides.