JPH02107476A - Multicolor thermal recording material - Google Patents

Abstract

PURPOSE:To ensure satisfactory color separation and obtain a clear four-color image by a construction wherein two inner thermal color forming layers and at least one of two outer thermal color forming layers are transparent, each of color forming systems for the inner color forming layers is a combination of an electron-donative dye precursor and a color developer, and each of color forming systems for the outer color forming layers is a combination of a diazo compound and a coupler. CONSTITUTION:A transparent cyan color forming layer 5 is provided on the back side of a transparent support 1, an opaque black color forming layer 6 is provided on the layer 5, a transparent magenta color forming layer 2 is provided on the face side of the support 1, a transparent yellow color forming layer 3 is provided on the layer 2, a transparent protective layer 4 is provided on the layer 3, and an opaque protective layer 7 is provided on the layer 6. Each of color forming systems for the black and yellow color forming layers is a diazo system, whereas each of color forming systems for the cyan and magenta color forming layers is a leuco system. When thermal recording is conducted on both sides of this recording material by thermal heads, black and yellow colors can be independently developed respectively on both sides of the support. Next, the recording material is irradiated with light in the photosensitive wavelength regions of diazo compounds in the black and yellow color forming layers to decompose the diazo compounds, thereby fixing the black and yellow layers. Then, thermal recording in the inner magenta and cyan layers is conducted by high thermal energy. As a result, cyan, magenta, yellow and black colors can be independently developed respectively on both sides of the support.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive recording material, and more particularly, the present invention relates to a multicolor heat-sensitive recording material capable of reproducing full colors.

(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 eject the ink, the nozzle is easily clogged with the colorant and other contents (and has major drawbacks such as a lack of recording reliability). 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, to obtain a four-color image, it is necessary to use four ink sheets. This requires the use of a large amount of ink sheets, which is uneconomical.Also, in the case of the inkjet method, the user must always be careful not to run out of ink liquid.
In the case of a thermal transfer method, it is necessary to take care not to run out 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 complicated 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. . 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 Japanese Patent Application No. 55-133991 and Japanese Patent No. 55-133992, there is a method in which a plurality of coloring 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. Other methods include, for example, Japanese Patent Publications No. 50-17868, No. 51-5791, No. 57
-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.

However, all of these methods not only have a small number of color hues that can be realized, but also have turbidity due to bleeding and color mixing, so it is difficult to say that they have sufficient functionality as color hard copies. In particular, 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. For example, if you want to increase the number of color hues, you can simply increase the number of fractions of applied heating energy and widen the energy difference between them, thereby creating a corresponding heat-sensitive coloring layer on the same support. However, in reality, if the applied heating energy is extended to a lower range than before, problems may arise in terms of storage stability (so-called fogging) of the recording material itself. On the other hand, when the applied heating energy is extended to a high range, new serious problems arise in terms of scorching of the image, poor print running properties due to fusion (for example, sticking), and shortening of the life of the thermal head.

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 silver 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.

On the other hand, examples of conventional heat-sensitive recording materials provided on a substantially transparent support include Japanese Patent Publication No. 40-20151, Japanese Patent Application No. 60-68875, and Japanese Patent Application No. 60-184483.
However, these were made for the purpose of obtaining high-contrast images or high-quality images with excellent gloss by viewing thermally recorded images from the transparent support side. Further, as an example in which heat-sensitive coloring layers are provided on both sides of a support, JP-A-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 of these is simply a dispersion of color forming components and color developing components in a solid state,
Due to the scattering of light, the coloring layer itself essentially becomes an opaque layer, making it impossible to obtain the desired multicolor image with clear color separation. In order to improve the transparency of the heat-sensitive coloring layer, there is a description of dissolving each component and applying it to the same layer, but in this case,
Color development of each component can easily occur even before printing.
This causes 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.

(Problem to be Solved by the Invention) As a result of intensive studies to solve the conventional drawbacks, the inventors of the present invention have developed a method of providing substantially transparent color-forming layers that develop different hues on both sides of a transparent support. It has been discovered that it is possible to obtain a thermally colored image with a higher degree of multicolor than ever before and has already been proposed (Japanese Patent Application No. 75409/1982). However, there was room for further improvement in the clarity of the images obtained in this way.As a result of intensive study by the present inventors to make the above-mentioned improvement, the present inventors found that A transparent layer is provided with two heat-sensitive layers, each of which develops a different hue, and the inner two heat-sensitive layers are a color-forming system that uses a combination of an electron-donating dye precursor and a color developer (leuco system). On the other hand, the coloring system of the outer two heat-sensitive layers is a combination of a diazo compound and a coupler, and all other heat-sensitive layers are substantially transparent, resulting in four colors with improved image clarity. The present invention was accomplished by discovering that it is possible to obtain multicolor images.

Therefore, a first object of the present invention is to provide a heat-sensitive recording material that can sufficiently control the color separation of color hues and obtain clear images in four colors.

A second object of the present invention is to provide a method for reproducing full-color images using heat-sensitive recording materials.

(Means for Solving the Problems) The above aspects of the present invention include at least a transparent support and two layers laminated on both sides of the transparent support, each layer having one of cyan, magenta, yellow, and black. A multicolor heat-sensitive recording material capable of reproducing a full-color image consisting of four heat-sensitive layers that develop color in one hue, comprising at least two inner heat-sensitive layers and two outer heat-sensitive layers among the four heat-sensitive layers. At least one of the heat-sensitive layers is substantially transparent, and the color-forming system of the inner heat-sensitive layer is a combination of an electron-donating dye precursor and a color developer, and the color-forming system of the outer heat-sensitive layer is a diazo compound. This was achieved using a multicolor heat-sensitive recording material characterized by a combination of a coupler and a coupler.

Next, a method for obtaining clear multicolor images using the multicolor thermosensitive recording material of the present invention will be explained with reference to the drawings.

Figure 1 shows a transparent support with a transparent cyan coloring layer on the back side, an opaque black coloring layer on top of it, a transparent magenta coloring layer on the front side, and a transparent yellow coloring layer on top of it.
The multicolor heat-sensitive recording material of the present invention includes a transparent protective layer provided above the yellow coloring layer and an opaque protective layer provided above the black coloring layer. In this case, the coloring system of the black coloring layer and the yellow coloring layer is a diazo type, and the coloring system of each of the cyan and magenta coloring layers is a leuco type.

Both outer heat-sensitive layers are assumed to develop color with the same applied heating energy, and if an image is thermally recorded from both sides with a thermal pen or thermal head, black and yellow will be produced independently on both sides of the support with substantially the same applied energy. Can produce color.

Next, the diazo compound used for the black and yellow layers is irradiated with light in the photosensitive wavelength range to decompose the diazo compound and fix the black layer and yellow layer. By thermally recording on the magenta and cyan layers, which have low sensitivity, cyan, magenta, yellow and black can be independently developed on both sides of the support. As a result, when viewed from the side of the transparent protective layer, cyan, magenta, and
A total of seven basic colors, yellow, cyan + magenta (blue), magenta + yellow (red), cyan + yellow (clean), and cyan + magenta + yellow (black), can be achieved with good color separation, and the hues of these colors are The color development of black allows for more precise adjustment. In this case, the reflected image is extremely clear because not only the black coloring 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. .

Next, the materials used in the multicolor heat recording material of the present invention will be described in detail.

The electron-donating dye precursor in the present invention has the property of donating electrons or accepting protons such as acids to develop color, and is not particularly limited, but is usually approximately colorless, and includes lactones and lactams. , sultone, spiropyran, ester, amide, etc., and these partial skeletons are ring-opened or cleaved upon contact with a color developer. Specifically, crystal violet lactone, benzoylleucomethylene blue, malachite green lactone, rhodamine B lactam, 1,3.
Examples include 3-trimethyl-6°-ethyl-8°-butoxyindolinobenzospiropyran.

The color developer for these color formers can be appropriately selected from known ones and used. For example, color developers for leuco dyes include phenolic compounds,
Sulfur-containing phenol compounds, carboxylic acid compounds, sulfone compounds, urea or thiourea compounds, etc.
5) on pages 49-54 and 65-70.

Among these, those with a melting point of 50°C to 250°C are particularly preferred, and among them, phenols and organic acids that are poorly soluble in water and have a melting point of 60°C to 200°C are preferred.When two or more color developers are used together, is preferred because it increases solubility.

Among the color developers used in the present invention, particularly preferred ones are represented by the following general formulas (I) to (IV).

(1) C, H,. .

(U) R1 is an alkyl group, an aryl group, an aryloxyalkyl group, or an aralkyl group, with methyl and butyl groups being particularly preferred.

m=O~2, n=2~11 C0OR R8 is an alkyl group, especially a butyl group, a pentyl group,
Heptyl and octyl groups are preferred.

R9 is a hydrogen atom or a methyl group, and n is 0-2.

(IV) R11) is an alkyl group, an aralkyl group or an aryloxyalkyl group.

In the present invention, 0.3 to 160 parts by weight, preferably 0.3 to 160 parts by weight of a color developer is added to 1 part by weight of the electron-donating dye precursor.
．． Preferably, 3 to 801 iffi parts are used.

The other diazo compound of the color forming material according to the multicolor heat-sensitive recording material of the present invention is one that reacts with a color developer called a coupling component to be described later to develop a desired hue, and When exposed to light of a specific wavelength, it decomposes and no longer has the ability to produce color even when a coupling component acts on it. The hue in this coloring system is mainly determined by the diazo dye produced by the reaction between the diazo compound and the coupling component. Therefore, as is well known, by changing the chemical structure of the diazo compound, the coloring hue can be easily changed by changing the chemical structure of the coupling component, and almost any coloring hue can be obtained depending on the combination. be able to.

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 it changes up to about nm. (“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 (1)
965)) 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.

Diazonium salt has the general formula ArN! It is a compound represented by +X- (wherein Ar represents a substituted or unsubstituted aromatic moiety, N2° represents a diazonium group, and X- represents an acid anion).

Among these, compounds having a photolysis wavelength around 400 nm include 4-diazo-1-dimethylaminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-1-dipropylaminobenzene, and 4-diazo-1-dimethylaminobenzene. 1-
Methylbenzylaminobenzene, 4-diazo-1-dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-17dimethylamino-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- Examples include 2,5-jethoxybenzene. 300-370
Compounds having a photolysis wavelength in nm include 1-diazo-4-(N,N-dioctylcarbamoyl)benzene,
1-Diazo-2-octadecyloxybenzene, l-diazo-4-(4-tert-octylphenoxy)benzene, 1-diazo-4-(2,4-di-tert-amylphenoxy)benzene, 1-diazo-2 -(4-te
rt-octylphenoxy)benzene, l-diazo-5
-chloro-2-(4-tert-octylphenoxy)benzene, ■-diazo2,5-bis-octadecyloxybenzene, l-diazo-2,4-bis-octadecyloxybenzene, 1-diazo-4- (N-octylteraroylamino)benzene and the like can be mentioned. The photolysis wavelength of the aromatic diazonium compounds typified by the examples listed above can be varied widely by arbitrarily changing the substituents.

Specific examples of acid anions include CnF and n+.

COO- (n represents 3 to 9), CmFtm+, SQ
, -(m represents 2 to 8), (Cj!F.

1+ +SOz )z CH- (l represents 1 to 18), H Specific examples of the diazo compound (diazonium salt) include the following examples.

Can be mentioned.

G Hz (CHl)3 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, Rt , Rs , Rs and R
4 is hydrogen, halogen, alkyl group, or alkoxy group, and R4 is a hydride halogen, alkyl group, amino group, benzoyl, mido group, morpholino group, trimercapto group,
Also, R is 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-benzylamino), 4-(N,N-dimethylamino), 4-(N,N-diethylamino), 4
-(N,N-diethylamino)-3-chlor, 4-pyrodino-3-chlor, 4-morpholino-2-methoxy,
It is a benzenediazosulfonic acid salt having a substituent such as 4-(4°-methoxybenzoylamino)-2,5-dibutoxy or 4-(4°-trimercapto)-2,5-dimethoxy. 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-ethylanthranic acid-5-sulfonitsutaacid, monoethanolamine, jetanolamine, guanidine, or the like.

The coupler used in the present invention forms a dye by coupling with a diazo compound (diazonium salt), and specific examples thereof include resorcinol, 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-propylamide, 2-hydroxy-3-naphthoic acid tetradodecylamide, acetanilide, acetoacetanilide , benzoylacetanilide, 1-phenyl-3-methyl-5-pyrazolone, 2,4-bis(benzoylacetamino)toluene,
l, 3-bis(pivaloylacetaminomethyl)benzene, 1-(2', 4°.

6°,-trichlorophenyl)-3-benzamide-5
-pyrazolone, 1-(2'4°6°trichlorophenyl)-3-anilino-5-pyrazolone, l-phenyl-3-phenylacetamido-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, indoles, imidazoles,
Examples include nitrogen-containing compounds such as imidacillins, triazoles, morpholines, piperidines, amidines, formazines, and pyridines. Specific examples of these are described, for example, in Japanese Patent Application No. 60-132990.

Two or more basic substances may be used in combination.

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.

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, and the permeation starting 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 (e.g., Japanese Patent Application Laid-open No. 59-91438, Japanese Patent Application No. 59-190).
No. 886, Japanese Patent Application No. 59-99490, etc.).

In order to control the glass transition point specific to the capsule wall, it is necessary to change the type of capsule wall forming agent. Examples of the wall material of the microcapsule include polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol, 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 suitable for dissolving the color developer or coupler described below is used, it has excellent solubility in the color former, increases the color density and speed of color development during thermal printing, and also increases the color development rate and color development rate during thermal printing. This is preferable because it can be reduced.

When making 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.

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, and includes a coupling component, a basic substance, a color former, a color developer, or a diazo Lowering the melting point of compounds, etc.
By lowering the softening point of the capsule wall, the diazo, basic substance, coupling component, color forming agent, and color developing agent are used to create a favorable reaction environment.

Coloring aids include phenolic compounds, alcoholic compounds, amide compounds, sulfonamide compounds, etc.
Specific examples include p-tert-octylphenol, p-benzyloxyphenol, phenyl p-oxybenzoate, benzyl carbanylate, phenethyl carbanylate, hydroquinone dihydroxyethyl ether, xylylene diol, N-hydroxyethyl-methanesulfonamide. , N-phenyl-methanesulfonic acid amide, and the like. 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, a color developer for an electron-donating dye precursor or a coupler for a diazo compound is dissolved in an organic solvent that is sparingly soluble or insoluble in water, and then is mixed with an aqueous phase containing a surfactant and 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 or coupler can be appropriately selected from among high-boiling point oils, but especially those having two or more benzene rings and having two or more heteroatoms, known as esters and pressure-sensitive oils. Preferably, the number of oils is equal to or less than the specified number. Such oils have the following general formula (V) ~ (■
) and triallylmethane (e.g., tritolylmethane, tolyldiphenylmethane), terphenyl compounds (e.g., terphenyl), alkyl compounds (e.g., terphenyl), alkylated diphenyl ethers (e.g., probyl diphenyl ether) , hydrogenated terphenyl (e.g. hexahydroterphenyl)
, diphenyl ether. Among these, it is preferable to use esters from the viewpoint of emulsion stability of the emulsified dispersion of the color developer or coupler.

(Vl) (V) 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 a Pl, Q
' represents an integer from 1 to 4, and the total number of alkyl groups is 4
No more than 100 pieces.

Incidentally, the alkyl groups for R' and R1 are preferably alkyl groups having 1 to 8 carbon atoms.

In the formula, R3 represents a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, R4 represents an alkyl group having 1 to 12 carbon atoms, and n is l.
Or represents 2.

p t and q t represent integers from 1 to 4; when n=1, the total number of alkyl groups is within 4, and when n=2
When , the total number of alkyl groups is 6 or less.

(■) In the formula, R% and R& represent a hydrogen atom or the same or different alkyl group having 1 to 1 carbon atoms.

m represents an integer from 1 to 13. R3 and q3 represent an integer of 1 to 3, and the total number of alkyl groups is 3 or less.

Note that the alkyl group of R5SR& is particularly preferably an alkyl group having 2 to 4 carbon atoms.

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

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

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

Examples of esters include phosphate 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), dioctyl tetrahydrophthalate, benzoate ester (ethyl benzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, benzyl benzoate),
Abietate ester (ethyl abietate, benzyl abietate), dioctyl adipate, isodecyl succinate, dioctyl azelaate, oxalate ester (
dibutyl oxalate, dipentyl oxalate), diethyl malonate, maleate esters (dimethyl maleate, diethyl maleate, dibutyl maleate), tributyl citrate, sorbate esters (methyl sorbate, ethyl sorbate, butyl sorbate) , sebacate ester (dibutyl sebacate, dioctyl sebacate),
Ethylene glycol esters (formic acid monoesters and diesters, butyric acid monoesters 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 borate, tripentyl borate), and the like.

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.

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

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 or coupler in the present invention is prepared by mixing an oil phase containing the color developer or coupler and an aqueous phase containing a protective colloid and a surfactant by high-speed stirring, ultrasonic dispersion, etc.
It can be easily obtained by mixing and dispersing using the means used for ordinary fine particle emulsification.

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.

Further, the ratio of the oil phase to the water phase (oil phase type it/water phase weight) is preferably 0.02 to 0.6, more preferably 0.1.
~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 the present invention, in addition to the above materials, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid, etc. can be added as acid stabilizers.

The heat-sensitive material of the present invention can be coated using a suitable 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/po in terms of solid content.

Further, the coating amount of the heat-sensitive layer is preferably between 3 g/rrf and 20 g/rrf, particularly between 5 g/rrf and 15 g/ryf. If it is less than 3 g/rrr, sufficient sensitivity cannot be obtained;
Even if the coating is applied in excess of g/rd, no improvement in quality will be observed, which will be disadvantageous in terms of cost.

In the present invention, it is preferable to provide an intermediate layer between the coloring layers from the viewpoint of improving the shelf life of the heat-sensitive recording material, the storage stability of recorded images, and color separation. It is preferable to use a layer formed by gelling a polymer with polyvalent cations.

Preferred water-soluble polyanionic polymers are those having carboxyl groups, sulfonic acid groups, and phosphoric acid groups, and particularly preferred are water-soluble polyanionic polymers having carboxyl groups. Examples of preferred water-soluble polyanionic polymers include natural or synthetic polyanionic polymers. Multi-IR gums (
Examples include alginate alkali metal salts, guar gum,
gum arabic, carrageenan, pectin, gum tragacanth, xanthine gum, etc.), polymers of acrylic acid or methacrylic acid and their copolymers, polymers of maleic acid or phthalic acid and their copolymers, cellulose derivatives such as carboxymethyl cellulose, gelatin , agar, etc., among which alginate alkali metal salts are preferred, the water-soluble polyanionic polymer has a molecular weight of 5,000 to io,
ooo is preferred, particularly from the viewpoint of barrier properties and manufacturing suitability aimed at in the present invention, from 10,000 to 40.0
00 is preferred. Polyvalent cations include salts of alkaline earth metals and their basic valence metals (e.g. CaCl, BaC
1t, Aj! *(SOn)s, ZnSO4, etc.), polyamines (eg, ethylenediamine, diethylenetriamine, hexamethylenediamine, etc.), and polyimines are preferred.

Another preferred example of the intermediate layer in the present invention is an ionic complex of a water-soluble polyanionic polymer and a water-soluble polycationic polymer. In this case, the various water-soluble polyanionic polymers described above can be used as the water-soluble polyanionic polymer.

Preferred water-soluble polycationic polymers include proteins having a plurality of reactive nitrogen-containing cationic groups, polypeptides such as polylysine, polyvinylamines, polyethyleneamines, polyethyleneimines, and the like.

When making an intermediate layer using these materials, one of the materials should be used as the first layer to prevent rapid gelation during application.
It is preferable to apply the material by including it in the coloring layer or the second coloring layer, but the temperature and pH may be further adjusted, or one material may be contained in the first coloring layer and the other material may be included in the second coloring layer. It is also possible.

The preferred coating amount of the intermediate layer is 0.05 g/m” to 5 g/m
”, more preferably 0.1 g/m2 to 2 g/m
” is.

In the heat-sensitive layer of the present invention, at least one of the two outer heat-sensitive layers and the two inner heat-sensitive layers are required to be substantially transparent in order to improve color separation. Substantially transparent here means haze (%) (manufactured by Nippon Seimitsu Kogyo ■,
(measured using an integrating sphere method HTR meter), it must be 60% or less. It is preferably 40% or less, more preferably 30% 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 relaxed 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.

Transparency as described above can be easily achieved by using color developers or couplers in the form of the emulsified dispersion.

It is preferable to provide a protective layer on the two outer heat-sensitive layers of the heat-sensitive recording material of the present invention in order to improve scratch resistance and prevent sticking. At least one of the protective layers must be substantially transparent. That is, if both protective layers and all the heat-sensitive layers are made substantially transparent, a full-color transmitted image can be obtained, but by making one of the protective layers an opaque layer containing a white pigment, the transparent protective layer becomes It can be seen from the side as a reflected image. In this case, in order to make the image clearer, the outer heat-sensitive layer on the side where the recorded image is viewed is the reflective side, that is, the heat-sensitive layer directly under the opaque protective layer, by a known method such as adding a white pigment or the like, or by adding the above-mentioned coupler. Instead of using an emulsified dispersion of the heat-sensitive layer, it is preferable to incorporate a coupler into the heat-sensitive layer in a conventional manner to make it opaque. 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.

Two or more protective layers may be laminated, or an opaque protective layer may be laminated on a transparent protective layer.

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

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

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 particle size of colloidal silica is preferably LOmμ to 100mμ, and the specific gravity is 1.1 to 1.3. In this case, the pH value of the colloidal solution is about 4 to about 1.
O 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 silicon-modified polyvinyl alcohol II (1 part colloidal silica
．． 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 transparent 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-anhydrous. Water-soluble polymers such as maleic 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, acrylic, nitrile-brassene rubber latex, methyl acrylate-butadiene rubber latex, and polyvinyl acetate emulsion. The amount used in combination is 0°O1 per 1 part by weight of silicon-modified polyvinyl alcohol.
~0.5 part by weight is preferred.

In the protective layer, pigments,
Metal soaps, waxes, crosslinking agents, etc. are added.

The pigment has a refractive index of 1. Pigments with a particle diameter of 4 to 1.55 μm or less are preferred. Specifically, there are calcium carbonate, talc, Rouseki, kaolin, aluminum hydroxide, amorphous silica, etc., and the amount of these added is 0.05 of the total weight of the polymer.
The amount is 0.5 to 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, and aluminum stearate, in an amount of 0.5 to 20% by weight, preferably 1 to 10% by weight of the total weight of the protective layer. It is added in 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 an amount 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, natrirum salts or ammonium salts such as di(2-ethylhexyl)sulfosuccinic acid and di(n-hexyl)sulfosuccinic acid. etc.

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/po, more preferably Ig to 3 g/rrr.

On the other hand, the opaque protective layer provided on the opaque heat-sensitive layer does not use the combination of silicon-modified polyvinyl alcohol and colloidal silica used in the transparent protective layer, or it further adds opacity to the components of the transparent protective layer. It can be easily provided by adding a white pigment for coloring. In particular, it is preferable to use various pigments not only to make the material opaque but also to improve its whiteness. These pigments have a particle size of 0. It is preferable to use an amount of 0.1 to 3 times, especially 0.3 to 2 times, the total weight of the polymer, and it is particularly preferable to use a white pigment with a refractive index of 1.55 or more.

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. Gelatin, synthetic polymer latex, nitrocellulose, etc. are used as the material for the undercoat layer. The coating amount of the undercoat layer is 0.
1g/nf~2. It is preferably in the range of Og/d, particularly preferably in the range of 0.2 g/po to 1.0 g/if.

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

The undercoat layer is coated with a hardening agent, since 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 quality of the image recorded on the heat-sensitive layer may deteriorate. It is desirable to harden using.

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-'; acryloyl-hexahydro-5-)riazine, 1.3.5-triacryloyl-
Active vinyl compounds such as hexahydro-8-triazine, 1,3,5-)rivinylsulfonyl-hexahydro-s-triazine.

■2.4-dichloro-6-hydroxy-8-triazine sodium salt, 2.4-dichloro-6-medoxy 5
-1-Ryazine, 2.4-dichloro-6-(4-sulfoanilino)-s-1-riazine sodium salt, 2.4
-dichloro-6-(2-sulfoethylamino)-S-)
Riasiso, N-N.

Active halogen compounds such as monobis(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-) Liethylene-s-triazine, 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'-(varaphenylene)bisisoxazole.

■Inorganic compounds such as chromium alum and chromium acetate.

■N-carboethoxy-2-isopropoxy-1,2-
Dihydroquinoline, N-(1-morpholinocarboxy)
Dehydrated condensed peptide reagents such as -4-methylpyridinium chloride, active ester compounds such as N,N'-aziboyldioxydisuccinimide, and N,'N'terephthaloyldioxydisuccinimide.

[Phase] Toluene-2,4-diisocyanate, l.

Isocyanates such as 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.
0.20 from heavy snowfall 3. An appropriate addition amount can be selected within the range of O1i% according to 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 allowed to last, and the undercoat layer will swell when the heat-sensitive layer is applied. If the amount is too high, the degree of curing will proceed too much, and the adhesion between the undercoat layer and the support will deteriorate, resulting in the disadvantage that the undercoat layer will become film-like and peel 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 the foam that occurs during application, or to add an activator to improve liquid leveling (and prevent the formation of application streaks). be.

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 or corona discharge treatment,
Glow discharge treatment etc. are used, but from the point of view of cost or simplicity, U.S. Patent No. 2.715.075, U.S. Pat. The corona discharge treatment described in, for example, No. 590, 107 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, 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 multicolor heat-sensitive 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.

In the case of the present invention, in which a diazo compound is used as a color-forming component in the outer heat-sensitive recording layer, it is particularly advantageous to provide an exposure zone for photolysis in order to improve the storage stability of images and increase the number of colors.

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 L-head multi-scan method in which the recording material returns to its original state, prints again, and then returns to its original state.The other method has recording heads equal to the number of colors to be recorded. This is a so-called multi-head l-scan method that has a light irradiation zone between them, and both methods may be combined 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.

In the multicolor heat-sensitive recording material of the present invention, it is sufficient that each heat-sensitive layer exhibits a coloring hue of Y (yellow), M (cyan), C (cyan), or K (black); Although the order of the coloring layers of YSM, C, etc. is not particularly limited, when viewed with a transparent image such as OHP,
The order is preferably Y, M, CSK or YSC, M from the front. When one of the outer heat-sensitive layers is made opaque and/or an opaque protective layer is provided thereon, it is preferable from the viewpoint of image clarity that the opaque outer heat-sensitive layer is a black coloring layer.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to obtain a full-color image with excellent hue, excellent color separation, and good image storage stability, which could not be obtained conventionally by the swearing recording method. Can be done.

(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,
It 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 form an emulsion with an average particle size of 2μ. Stirring was continued for 3 hours at 40°C.

After cooling this liquid to 20°C, Amberlite IR-
120B (manufactured by Rohm and Haas (product name))
00 cc was added, stirred for 1 hour, and then filtered to obtain capsule liquid A.

Kaboo-A's Triphenylguanidine (base) Part 6 1.4 parts coupler CH.

CH3 14 parts Tricresyl phosphate 10 parts Ethyl acetate 20 parts A solution of the above composition was added to 170 parts of a 4% by weight aqueous solution of polyvinyl alcohol, mixed, and emulsified at 20°C to form a coupler/base with an average particle size of 1.5 μm. An emulsified dispersion was obtained.

Mix m-B ■, 170 parts of polyvinyl alcohol (Kuraray PVA205) 4% by weight aqueous solution ■, 10 parts of coupler 2-hydroxy-3-naphthoic acid anilide (naphthol AS) ■ A. Bacofen
Dispersed by A.G. Co., Ltd. (product name), with an average particle size of 3 μm.
A dispersion was obtained.

As an electron-donating dye precursor, IIl, triphenylguanidine (base) 6 parts 1-phenyl-1-xylylethane 55 parts methylene chloride 55 parts Sumithorpe 2
00 (ultraviolet absorber manufactured by Sumitomo Chemical ■) 2 parts Takenate D-11ON (manufactured by Takeda Pharmaceutical Company ■ (trade name)) 60 parts were mixed together and 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol were added.
2 parts and 40 parts of distilled water.
Emulsification and dispersion was carried out at 0''C to obtain an emulsified dispersion having an average particle size of 1 μm.Next, the obtained emulsion was continuously stirred at 40°C for 3 hours to obtain capsule liquid B.

A color developer represented by the following structural formula was dissolved in 8 parts of (a), 4 parts of (c), 3 parts of (C), 8 parts of 1-phenyl-1-xylylethane, and 30 parts of ethyl acetate. The obtained color developer solution was mixed with 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol and 1 part of water.
50 parts, and 0.5 parts of sodium dodecylbenzenesulfonate
emulsified and dispersed in an aqueous solution of
An emulsified dispersion was obtained.

Color developer (a) Color developer (b) Color developer (C) 〇4H9 Capsule゛C! ! The following compound (CIBA
Pergascript Red l-6-8)
14 parts, Cm H+t 1-phenyl-1-xylylethane 55 parts Methylene chloride 55 parts Sumithorp 2
00 (ultraviolet absorber manufactured by Sumitomo Chemical ■) 2 parts Takenate D-11ON (manufactured by Takeda Pharmaceutical Company Limited (trade name)) 60 parts were mixed to form an aqueous solution consisting of 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol and 40 parts of distilled water. After adding it to the inside, emulsification and dispersion was carried out at 20° C. to obtain an emulsified dispersion having an average particle size of 1 μm. Next, the obtained emulsion was continuously stirred at 40°C for 3 hours to obtain capsule liquid C.

A: Silica-modified polyvinyl alcohol (PVA manufactured by Kuraray)
R2105) 10-layer standing liquid 10 parts Colloidal silica (Snowtex 30 manufactured by Nissan Chemical ■) 30i
Ikei% liquid 5 parts Zinc stearate (Hydrin Z7 made by Middle East Oil & Fats) 30 parts heavy wall liquid
0.42 parts paraffin wax (Hydrin P-7 manufactured by Middle East Yushi ■) 30 parts heavy wall liquid 0.
42 parts were mixed to obtain a protective layer liquid A.

B: Silica-modified polyvinyl alcohol (PVA manufactured by Kuraray)
R2105) 10% by weight aqueous solution 15 parts Colloidal silica (Snowtex 30 manufactured by Nissan Chemical ■) 30% by weight aqueous solution 8.5 parts Zinc stearate (Hydrin 2-7 manufactured by Middle East Oil & Fats ■) 30 heavy wall muscle aqueous solution
0゜42 parts Paraffin wax (Cellosol D-130 manufactured by Middle East Oil Co., Ltd.) 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.

After corona discharge treatment was applied to both sides of a 75μ thick biaxially stretched polyethylene terephthalate film, a mixed solution of 85.0 parts of capsule liquid and 10.0 parts of color developer dispersion A was dried. The coating was applied in an amount of 6 g/rrl.

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 Ig/
It was applied so that it became mt.

Furthermore, 6 parts of capsule liquid A and 85.5 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 solution B was applied so that the dry coating amount was 2 g/m''.

A mixed solution of 5.0 parts of capsule liquid C and 10.0 parts of color developer dispersion A was applied to the other side of the above-mentioned coating layer in a dry coating amount of 6.
g/m'', then apply 3% by weight of sodium alginate (Snow Algin SH manufactured by Fuji Chemical) as an intermediate layer.
The aqueous solution was applied so that the dry coating amount was 0.5 g/rrr.

Next, 6 parts of capsule liquid A, 5 parts of coupler/base dispersion liquid
．． A mixture of 5 parts of calcium chloride and 0.5 parts of a 10% by weight aqueous solution of calcium chloride was applied so that the dry coating amount was 6 g/rrl.

Thereafter, protective layer liquid A was coated at a dry coating amount of 2 g/rrr to obtain a recording sheet.

Coating was done using a wire bar and then dried in an oven at 50'C.

The surface of the obtained recording sheet coated with protective layer liquid B was thermally printed with low energy (thermal head voltage 13V,
A black diazo colored image was fixed by irradiating light for 10 seconds using a Ricopy Super'-Dry 100 model for printing time θ~2.5 m5ec).

After that, the thermal head voltage was 18V and the printing time was 2.5~5.
m5ec), a cyan image was added.

Next, thermal printing was performed with low energy from the side to which the protective layer liquid A was applied (thermal head voltage 15V, printing time 0).
~2.5m5ec), and a yellow diazo colored image was fixed by irradiating it with light for 10 seconds using a Riff Piece Pardry Model 100. After that, thermal printing was performed with a higher energy than the above printing energy at a thermal head voltage of 15V and a printing time of 2.
5-5 msec), a magenta image was added.

When the obtained image was observed from the side coated with the protective layer liquid A (transparent protective layer side), a clear full-color image was obtained.

[Brief explanation of the drawing]

FIG. 1 is an example of a cross-sectional configuration diagram of a heat-sensitive recording material according to the present invention. l...Transparent support 2...Transparent magenta coloring layer 3...Transparent yellow coloring layer 4...Transparent protective layer 5...Transparent cyan coloring layer 6... - Opaque black coloring layer 7... Opaque protective layer

Claims (1)

[Claims] 1) At least a transparent support and four heat-sensitive layers laminated on each side of the transparent support, two layers each, each layer developing a hue of cyan, magenta, yellow, or black. A multicolor heat-sensitive recording material capable of reproducing a full-color image consisting of at least two inner heat-sensitive layers among the four heat-sensitive layers and at least one heat-sensitive layer among the two outer heat-sensitive layers. It is substantially transparent, and the coloring system of the inner heat-sensitive layer is a combination of an electron-donating dye precursor and a color developer, and the coloring system of the outer heat-sensitive layer is a combination of a diazo compound and a coupler. Multicolor heat-sensitive recording material. 2) The multicolor heat-sensitive recording material according to claim 1, further comprising a protective layer on the outer heat-sensitive layer, and at least the protective layer on the transparent heat-sensitive layer is substantially transparent. 3) Only one of the protective layers provided on the outer heat-sensitive layer is substantially transparent, and among the four heat-sensitive layers, only the outer heat-sensitive layer immediately below the opaque protective layer is opaque. The multicolor thermosensitive recording material according to claim 2.