JPH01285382A - Multi-color thermal recording medium - Google Patents

Abstract

PURPOSE:To control the number of hues and a color separation to obtain a sharp multi-color image, by laminating an opaque protective layer on a color forming unit layer of one outermost side and a transparent protective layer on a color forming unit layer of the opposite side. CONSTITUTION:On one surface of a transparent substrate 1, a heat-sensitive layer 6 forming Yellow is provided, and on the opposite surface thereof, a transparent Magenta forming layer 2 is provided. Thereon, a transparent Cyan forming layer 3 is laminated. On the Yellow forming layer 6, an opaque protective layer 5 is formed, and on the Cyan forming layer, a transparent protective layer 4 is formed. In this case, firstly the Yellow layer and the Cyan layer on the both sides of the substrate are colored independently of each other by applying a thermal recording with a low heat energy. After that, the colors are optically fixed by using a light source of a specific wavelength suitable for selectively optically decomposing only the diazo in Yellow and Cyan. Then, a low-sensitive Magenta layer on the inner side is thermally recorded with a heat energy relatively higher than the preceding time, whereby Cyan, Magenta, and Yellow can be formed on the both sides of the substrate independently of each other.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heat-sensitive recording material that develops multiple colors, and more specifically, the present invention relates to a heat-sensitive recording material that develops multiple colors. This invention relates to a multicolor heat-sensitive recording material.

(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 forming agent and 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 method in which ink containing a coloring agent is ejected from a narrow nozzle, the nozzle is easily clogged with the coloring agent and other contents, resulting in a major drawback in that recording reliability is lacking. 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. However, a large amount of ink sheets are used, which is uneconomical. Furthermore, in the case of the inkjet method, the user must always be careful not to run out of ink liquid, and in the case of the thermal transfer method, the user must be careful 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 multicolor recording 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 blurring and turbidity due to color mixing, so it is difficult to say that they have sufficient functionality as a color hard copy, especially as a color hard copy. In principle, a fatal drawback was that the number of color hues produced was small.

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 difference in energy development between them, so that the corresponding heat-sensitive coloring layers can be formed on the same support. It would be possible to design a heat-sensitive recording material with multiple heat-sensitive recording materials on the top, but in reality, if the applied heating energy is extended to a lower range than before, there will be problems in terms of storage stability (so-called capri) 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 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.

(Problems to be Solved by the Invention) In contrast, 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. 60-68875. Showa 60-184483
No. 1, but these were made for the purpose of obtaining a high-quality image with high contrast and excellent gloss by viewing a thermally recorded image from the side of a transparent support. 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. Furthermore, 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,
Color development of each component can easily occur even before printing.
This produces the so-called capri. Therefore, in any case, the above-mentioned known techniques have a small number of possible color divisions (and are essentially insufficient as a multicolor recording material).

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 has been discovered that colored images can be obtained and has already been proposed (Japanese Patent Application No. 75409/1982). However, the images obtained in this way have room for further improvement in terms of clarity. As a result of intensive studies to improve the above, the inventors found that a transparent protective layer was provided on the - side, an opaque protective layer was provided on the other side, and the transparent protective layer side As a multicolored reflective image can be seen from the outside (and that the clarity of the multicolored image can be improved by combining a substantially transparent thermosensitive coloring layer and an optionally opaque thermosensitive coloring layer, and further, The inventors have discovered that a multicolor image of higher quality can be obtained by providing an intermediate layer of a specific composition between the laminated coloring layers, and have thus arrived at the present invention.

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

A second object of the invention is to provide a method for improving the image sharpness of multicolor images.

(Means for Solving the Problems) The above-mentioned aspects of the present invention are such that one or more coloring unit layers capable of developing different hues are provided on one side of a transparent support, and each coloring unit layer capable of developing different hues is provided on the other side. Can be colored in different hues2
This is a multicolor heat-sensitive recording material having more than one color forming layer, in which an opaque retaining iiN is laminated on the outermost color forming unit layer on one side, and an opaque retaining iiN is laminated on the color forming unit layer provided on the opposite side. This was achieved by a multicolor heat-sensitive recording material characterized in that a transparent protective layer is laminated on the top of the transparent protective layer, and a multicolor reflective image can be seen from the side of the transparent protective layer.

Next, a method for obtaining a clear multicolor image using the multicolor heat-sensitive recording material of the present invention (hereinafter simply referred to as heat-sensitive material) will be described with reference to the drawings.

For example, a heat-sensitive layer that develops a yellow color on one side of a transparent support,
A transparent magenta coloring layer is provided on the opposite side, followed by a transparent cyan coloring layer, an opaque protective layer is provided on the yellow coloring layer, and a transparent protective layer is provided on the cyan coloring layer (see Figure 1). ), in this case, in order to independently develop the three colors, it is desirable to adopt a system of a coupling color development reaction of a diazo compound and a light fixation reaction as disclosed in JP-A-61-40192, i.e. First, the yellow layer and cyan layer on both outer surfaces of the support are independently colored by thermal recording with low thermal energy. After that, photofixing is performed using a light source with a specific wavelength that selectively photodecomposes only yellow and cyan diazo.Next, the inner magenta layer, which has low thermal sensitivity, is thermally recorded using relatively higher thermal energy than the previous time. For example, cyan, magenta, and yellow colors can be developed independently on both sides of the support. Moreover, the thermal energy used to develop the color of the magenta layer does not place an excessive burden on the recording material and apparatus, so it has great practical significance.
When viewed from the side of the transparent protective layer, cyan, magenta, yellow, cyan, magenta (blue), magenta + yellow (red), and cyan +
Yellow (green), cyan + magenta + yellow (
This means that a total of seven basic colors (black) can be realized with good color separation (see Figure 2). Incidentally, since the yellow coloring layer is separated from the support, all of the above-mentioned colors can be reproduced without fixing. In this case, the reflected image becomes extremely clear due to the opaque protective layer provided on the yellow coloring layer, but in this case, if an opaque coloring layer is used as the yellow coloring layer, the degree of opacity can be completely reduced. Therefore, a clearer multicolor image can be obtained. Furthermore, color separation can be further improved by providing a transparent intermediate layer between the magenta coloring layer and the cyan coloring layer. or,
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 realized by color mixing can be synergistically increased.

The material used for thermal recording according to the present invention is a component that causes a coloring reaction based on contact of substances by heating, and such components include a combination of an acidic substance and a basic dye precursor, and a combination of a diazo compound and a camping compound. Combinations can be mentioned.

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 violet lactone, benzoylleucomethylene blue, malachite green lactone, rhodamine B-raftam, 1,3.3-)dimethyl-6゛-ethyl-8゜
-butoxyindolinobenzospiropyran, etc.

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, especially phenol which is poorly soluble in water and has a melting point of 60°C to 200°C.
Organic acids are preferred.

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 coloring material according to the present invention is one that develops a desired hue by reacting with a color developer called a coupling component, which will be described later. It decomposes when exposed to light and no longer has the ability to develop color even when a coupling component acts on it. The hue in this coloring system is mainly determined by the diazo dye produced by the reaction between the diazo compound and the coupling component. Therefore, as is well known, the coloring hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupling component, and almost any coloring hue can be obtained depending on the combination. I can do it.

°For this reason, various diazo compounds may be contained in one layer, and one type of coupling component or other additives may be incorporated in the same layer. In this case, each unit coloring group is different. Consists of a diazo compound, common coupling components, and other additives. Also, there is a combination in which separate coupling components are contained in several layers and the same diazo and other additives are incorporated in each layer. At this time, each unit coloring group is composed of a different coupling component and a common diazo compound and additive. In any case, each unit coloring group is a combination of units having different coloring hues.
It is composed of one or more diazo compounds, 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. Hereinafter, explanation will be given mainly using diazonium salt as a representative 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 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 Adai 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, and if the chemical structure of the diazonium salt is changed, it can undergo a coupling reaction with the same coupling component. The hue of the dye also changes when it is applied, and it can be preferably used in the present invention.

A diazonium salt is a compound represented by the general formula ArN, "X - (wherein Ar represents a substituted or unsubstituted aromatic moiety, N2° represents a diazonium group, and
- represents an acid anion. ). In the present invention, it is one of the preferred embodiments to use diazonium compounds having different photodecomposition wavelengths, but examples of compounds having photodecomposition wavelengths around 400 nm include 4-diazo-1-dimethylaminobenzene, 4-diazo- 1-diethylaminobenzene, 4
-Diazo-1-dipropylaminobenzene, 4-diazo-11-methylbenzylaminobenzene, 4-diazo-
1-dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-
diethylamino-3-methoxybenzene, 4-diazo-
1-dimethylamino-2-methylbenzene, 4-diazo-1-benzoylamino-2,5-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-
Toluylmercapto-2゜5-jethoxybenzene, 4
-Diazo-1,4-methoxybenzoylamino-2,5
- Jetoxybenzene, etc. can be mentioned, and 300~
As a compound having a photolysis wavelength of 370 nm, l-
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, -diazo2
(4tert-octylphenoxy)benzene, l-diazo-5-chloro-2-(4-tert-octylphenoxy)benzene, l-diazo-2,5-bis-occudecyloxybenzene, l-diazo-2,4- Aromatic diazonium ip compounds represented by zero or more examples, such as octadecyloxybenzene, 1-diazo-4-(N-octylteraroylamino)benzene, etc. By arbitrarily changing the wavelength, the photolysis wavelength can be varied widely.

Specific examples of acid anions include CB F z n*+C
oo - (n represents 3 to 9), C-F! -, I
SO3- (m represents 2 to 8), CGIFzt, +S
Oz) z CH- (L represents 1-18), +*
Examples include Mz7, UNF1 PF, and the like.

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

The compound represented by the general formula is a compound represented by the general formula. In the formula, R1 is an alkali metal or an ammonium compound, Rz, R,, R5 and R1 are hydrogen, halogen, alkyl group, or alkoxyl group, and R4 is hydrogen, halogen, alkyl group, amino group, benzoylamido group, or morpholino group. , trimercapto group, or pyrrolidino group.

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

Among these compounds, preferred 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-”lor,
4-Birodinino-3-''lor, 4-morpholino-2-methoxy, 4-(4'-methoxybenzoylamino)-2,5-dibutoxy, 4-(4'-trimercapto)-2,5-dimethoxy, etc. It is a benzene diazosulfonate having a substituent.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, etc.
-28'7485 can be mentioned.

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, virols, 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.

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 a part of the components and use them from the viewpoint of controlling the color development sensitivity.

The type of microcapsules used in this case is not particularly limited, but microcapsules that are particularly preferred in the present invention are those that prevent contact between the substances of the capsule wall material at room temperature due to the substance isolation effect of the microcapsule walls. The permeability of a substance increases only while it is heated above that 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 additive 9, 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 (e.g., JP-A-59-91438, JP-A-59-190886,
(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. The wall materials for the microcapsules include polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene, methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol, etc. Can be mentioned. In the present invention, two or more of these polymeric substances can also be used in combination.

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

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

Here, the organic solvent for forming oil droplets can generally be appropriately selected from high boiling point oils, but
In particular, when an organic solvent suitable for dissolving 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 also reduces fog. 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, basic dye precursor 1! It is preferable to use 0.3 to 160 parts by weight, preferably 0.3 to 80 parts by weight, of the color developer for 1 part of i.

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 (preferably manufactured) are not ruptured by heat or pressure as used in conventional recording materials, and the reactive substances contained in the core and 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, 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, it creates a situation where diazo, basic substances, coupling components, color formers, color developers, etc. can easily react.

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-methanesulfonic acid amide. , 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, 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 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 less than the specified number. Such oils include compounds represented by the following general formulas (1) to (IV), triallylmethane (e.g. tritolylmethane, tolyldiphenylmethane), terphenyl compounds (e.g. terphenyl), alkyl compounds (e.g. terphenyl), alkylated diphenyl ether (
Examples are EVA, propyl diphenyl ether), hydrogenated terphenyl (eg, hexahydro terphenyl), and diphenyl ether. Among these, it is preferable to use esters from the viewpoint of emulsion stability of the emulsified dispersion of the color developer.

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. p I,
q + represents an integer of 1 to 4, and the total number of alkyl groups is 4 or less.

In addition, the alkyl group of RI and R2 is preferably an alkyl group having 1 to 8 carbon atoms.

(n) In the formula, R 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.

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

(In the formula II, R5' and Rh represent a hydrogen atom or the same or different alkyl group having 1 to 18 carbon atoms.

m represents an integer from 1 to 13. p2, q3 are 1~
represents an integer of 3, and the total number of alkyl groups is 3 or less.

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

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

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

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

Examples of esters include phosphate esters (for example, triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate, cresyl diphenyl phosphate), phthalate esters (
Diptyl 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 esters (diptyl 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.

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

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

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

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

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

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

The heat-sensitive recording 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.

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.

Further, the heat-sensitive recording material of the present invention can be viewed as a reflected image from one side of the transparent support, but if the back side of the background part is seen through, the image will be dull, so in order to make it look white, As will be described later, an opaque protective layer containing a white pigment is provided on the outermost heat-sensitive layer on the reflective side, which is the side on which 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.

It is preferable to employ an opaque heat-sensitive layer as the outermost heat-sensitive layer provided with the above-mentioned opaque protective layer, since this can further increase the clarity of the image. This opaque heat-sensitive layer may further contain a white pigment to be added to the protective layer.

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 these as a solid dispersion using a sand mill or the like. In this case, each coloring component etc. is 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, and the coloring components other than diazo and the color developer are added in an amount of 5 to 40% by weight, respectively, to this water-soluble polymer solution.The dispersed particle size is preferably 10μ or less. .

Further, the coating amount of the heat-sensitive layer is preferably between 3 g/rrr and 20 g/rrr, particularly between 5 g/rrr and 15 g/rd. Sufficient sensitivity cannot be obtained below 3 g/rrl;
Even if the coating is applied in excess of g/%, no improvement in quality will be observed, which will be disadvantageous in terms of cost.

In the heat-sensitive layer of the present invention, all layers except the outermost layer on one side of the support must be substantially transparent in order to improve color separation. Substantially transparent here means haze (%) (manufactured by Nippon Seimitsu Kogyo ■, integrating sphere method HT).
It must be 40% or less, preferably 30% or less, and more preferably 20% or less (as measured by R meter). 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 provided on top of the transparent 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-58-193T89.
It is listed in the issue announcement.

The colloidal silica used in the present invention is used as a colloidal solution in which ultrafine particles of silicic anhydride are dispersed in water using water as a dispersion medium. The colloidal silica particles preferably have a particle size of 10 mμ to 100 mμ and a specific gravity of 1.1 to 1.3. The pH value of the colloidal solution in this case is about 4 to about 1
0 is preferably used. ``When the 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 extremely good. Furthermore, since the mechanical strength of the heat-sensitive layer surface is improved, the transparency of the entire heat-sensitive recording material can be further improved.

A suitable blending ratio of silicon-modified polyvinyl alcohol and colloidal silica in the present invention is 0.00 parts by weight of colloidal silica to 1 part by weight of silicon-modified polyvinyl alcohol.
The amount is 5 to 3 parts by weight, more preferably 1 to 2 parts by weight. If the amount of colloidal silica used is less than 0.5 parts by weight, the effect of improving transparency will be small, and if it is used more than 3 parts by weight, cracks will occur in the protective layer, and the transparency will be reduced.

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

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

The pigment preferably has a refractive index of 1.4 to 1.55 and a particle size of 1 μm or less. Such pigments include calcium carbonate,
Talc, Rouseki, kaolin, aluminum hydroxide, amorphous silica, etc., are added in an amount of 0.05 to 0.5 times, particularly preferably 0.1 to 0.3 times, the total weight of the polymer. It is. 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, which will impair its commercial value.

Metal soaps include emulsions of higher fatty acid metal salts such as zinc stearate, calcium stearate, and aluminum stearate, and the amount thereof is 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, methylolstearamide, polyethylene wax, and silicone, and the proportion thereof is 0.5 to 40% by weight, preferably 1 to 20% by weight of the total weight of the protective layer. is added in an amount of

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.

In addition, 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 0. 2 to 5 g/rrf is preferable, and more preferably 1 g to 3 g/rrf.

On the other hand, the composition of the opaque protective layer provided on the (opaque) heat-sensitive layer is the same as that of the transparent protective layer, except that the combination of silicon-modified polyvinyl alcohol and colloidal silica used in the transparent protective layer is not used. In particular, it is preferable to use various pigments to improve the whiteness. These pigments have a particle size of 0.01 μm to 8 μm in an amount of 0.1 to 3 times the total weight of the polymer, especially 0.01 μm to 8 μm. 3-2
It is preferable to use double the amount, and in particular, it is preferable to use a white pigment with a refractive index of 1.55 or more.

Furthermore, in the present invention, providing an intermediate layer between the laminated color-forming layers not only makes the interface between two phases clear when applying the color-forming layer, but also improves the storage stability and independent color-forming properties after producing the heat-sensitive recording material. , is preferable because color separation can be further improved. In the present invention, particularly good results can be obtained when a layer formed by gelling a water-soluble polyanionic polymer with polyvalent cations is used as the intermediate layer.

Preferred water-soluble polyanionic polymers are polymers 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 multi-W gums (such as alginate alkali metal salts, guar gum, gum arabic, carrageenan, pectin, tragacanth gum, xanthine gum, etc.), acrylic acid or methacrylic acid. and copolymers thereof, polymers of maleic acid or phthalic acid and copolymers thereof, cellulose derivatives such as carboxymethyl cellulose, gelatin, agar, and the like, among which alginate alkali metal salts are preferred. The molecular weight of the water-soluble polyanionic polymer is 5,000 to 10,00
0 is preferable, particularly from the viewpoint of barrier properties and manufacturing suitability aimed at in the present invention, 10,000 to 40,000
is preferred. Examples of polyvalent cations include alkaline earth metals and their basic value metal salts (e.g. CaC1z, BaCjl
! 2, Al (soa) 3, ZnSO4, etc.),
Polyamines (eg, ethylenediamine, diethylenetriamine, hexamethyldiamine, 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 creating an intermediate layer using these materials, one of the materials should be used to prevent rapid gelation during application.
It is preferable to apply it by including it in either the upper or lower coloring layer. It is also possible to adjust the temperature and pH, or to include one material in the laminated coloring layer and the other material in the laminated coloring layer.

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

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, polyolefin films such as polypropylene and polyethylene, etc. It can be used by itself or by bonding them together.

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
．． 1g/rrf~2. Og/rr? It is preferably in the range of 0.2 g/rri to 1.0 g/ri, particularly preferably 0.2 g/rri to 1.0 g/ri.

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

A hardening agent is used for the undercoat layer because when the heat-sensitive layer is coated on top of it, the image quality of the heat-sensitive layer may deteriorate if the undercoat layer swells due to water contained in the heat-sensitive layer. It is recommended that the product be cured.

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-) liazine, 1.3.5-triacryloyl-hexahydro-5-) riazine, 1.3.5-trivinylsulfonyl-hexahydro-5 -) activated vinyl compounds such as riazine.

■2.4-dichloro-6-hydroxy-3-triazine sodium salt, 2.4-dichloro-6-methoxy=S
-) riazine, 2,4-dichloro-6-(4-sulfoanilino)-3-) riazine sodium salt, 2,4-dichloro-6-(2-sulfoethylamino)-S-triazine, N-No- Bis(2-chloroethylcarbamyl)
Active halogen compounds such as piperazine.

■Bis(2,3-epoxypropyl)methylpropylammonium P-)luenesulfonate, 1,4-bis(2°,3′-epoxypropyloxy)butane, 1,
3.5-) Epoxy compounds such as liglycidyl isocyanurate and 1,3-diglycidyl-5-(γ-acetoxyβ-oxypropyl)isocyanurate.

■2.4.6-) diethylene-S-triazine, 1,
6-hexamethylene-N, N”-bisethyleneurea,
Ethylenimino compounds such as 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-)dimethylaminopropyl)carbodiimide-p-trienesulfonate, l-ethyl-3-(
3-dimethylaminopropyl) carbodiimide hydrochloride.

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

■Inorganic compounds such as chromium alum and chromium acetate.

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

[Phase] Toluene-2.4-diisocyanate, 1°6-
Isocyanates such as hexamethylene diisocyanate.

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

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

If the amount added is less than 0.20% by weight, the degree of curing will be insufficient no matter how long it is 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, caustic soda or the like may be added to bring the pH of the liquid to the alkaline side, or;
The pH of the solution can also be made acidic using citric acid or the like.

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

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

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

Activation treatment methods include acid etching treatment,
Flame treatment using a gas burner, corona treatment, glow discharge treatment, etc. are used, but from the point of view of cost or simplicity, U.S. Pat.
No. 846,727, No. 3,549,406, No. 3
．． 590. 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 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, 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 heat-sensitive recording 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 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. Furthermore, when using a diazo compound as a color-forming component, it is advantageous to have an exposure zone for photolysis, especially for image preservation and multicolor production. There are two different methods. One is to irradiate light for photolysis after printing once, and before and after this irradiation, the recording material is in a state where it is ready for printing so that it can be printed again at the place where it has been printed by the feeding mechanism of the recording material. This is the so-called L-head multi-scan method, in which the recording material returns to its original position, prints again, irradiates the light again, and returns to its original state. This is the so-called multi-head, one-scan method, which has a light irradiation zone between them, and both methods may be combined as necessary.
Further, the thermal energy applied to the head may be changed as necessary. In addition, as a light source for photolysis, various light sources that emit light of a desired wavelength can be used, such as various fluorescent lamps, xenon lamps, xenon flash lamps, mercury lamps of various pressures, photographic flashes, and strobes. Various light sources can be used. Further, in order to make the optical fixing zone compact, the light source section and the exposure section may be separated 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 light, fixing it mainly with light in the visible range, and then printing again. .

(Effects of the Invention) As detailed above, although the outermost layer on one side of the heat-sensitive layer of the multicolor heat-sensitive recording material of the present invention may be opaque,
Since all other layers are substantially transparent, excellent hues, which could not previously be obtained by thermal recording methods,
A multicolor image with excellent color separation and image storage stability can be obtained. Furthermore, color separation, storage stability, etc. can be further improved by providing an intermediate layer between the stacked heat-sensitive layers.

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

Note that "r parts" indicating the amount added represents "r parts by weight".

Capsule: BjJll of A Diazo compound below 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.) Product name)) Mix 24 parts,
Polyvinyl alcohol (Ri-7shiPVA-217E) 8
After adding it to an aqueous solution consisting of 63 parts of a superimposed aqueous solution and 100 parts of distilled water, it was dispersed at 20'C to obtain a lambda, and the average particle size was 2μ.
The resulting emulsion was kept stirring at 40°C for 3 hours.

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.

Kabu Kazuichi Voice ＼ N A's 3 o's 1 1. Polyvinyl alcohol (Kuraray PVA205) 4% by weight aqueous solution 170 parts■Subordinate. Coupler 14 parts Triphenylguanidine (base) 6 parts Color development aid 14 parts
Dispersed by A.G. Co., Ltd. (product name), with an average particle size of 3 μm.
A dispersion was obtained.

Capseno L/? Spirit of B [As a basic colorless dye, l-phenyl-1-xylylethane
55! ′■Methylene chloride
55 parts Sumisorb 200 (ultraviolet absorber manufactured by Sumitomo Chemical ■) 2 parts Takene) D-11ON (manufactured by Takeda Pharmaceutical Co., Ltd. (trade name)) 60 parts were mixed together, and 100% polyvinyl alcohol 8th grade aqueous solution was added.
After adding IJn to an aqueous solution consisting of 40 parts of distilled water and 40 parts of distilled water, an emulsified dispersion with an emulsion molecule of 1 IIL and an average particle size of 1 μ was obtained at 1.20°C. Next, the obtained emulsion was heated at 40°C. Stirring was continued for 3 hours to obtain capsule liquid B.

True color \n? A's 8°-1 H＼ 8 parts of color developer (a), 4 parts of (b) and 3 parts of H (C) represented by the following structural formula are mixed with 8 parts of 1-phenyl-1-xylylethane and 30 parts of ethyl acetate. It was dissolved in parts. The obtained color developer I11 solution was mixed and emulsified into an aqueous solution of 100 parts of an 8% by weight polyvinyl alcohol solution, 150 parts of water, and 0.5 parts of sodium dodecylbenzene sulfate to obtain a particle size of 0.
．． A 5u emulsified dispersion was obtained.

1- Color developer (a) Color developer Φ) Color developer (C) 4He Capsule, the following compound (CI[1AP
srHascripL Red l-6-8)
I/I N”I, l-phenyl-1-xylylethane 55 parts Methylene chloride
55 parts Sumithorp 200 (ultraviolet absorber manufactured by Sumitomo Kagaku ■) 2 parts Takene) D-11ON (manufactured by Substitute Pharmaceutical Industry Co., Ltd. (trade name)) 60 parts mixed, 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol and 40 parts of distilled water After adding it to an aqueous solution consisting of 1000 ml of 100 ml of 1000 ml of 1000 ml of aqueous powder, it was emulsified and dispersed at 20°C to obtain an emulsified dispersion having an average particle size of lμ. next,
The resulting emulsion was continuously stirred at 40°C for 3 hours to obtain Capsule Liquid C.

Desired 1 plate A Dantachike Silica-modified polyvinyl alcohol (PVA manufactured by Kuraray)
R2105) 10 heavy liquid 10 parts colloidal silica (Snowtex 30 manufactured by Nissan° Chemical @) 3
0% by weight liquid 5 parts Zinc stearate (
Hydrin 2-7) manufactured by Middle East Oil ■ 30% by weight liquid
0.42 parts paraffin wax (Middle East oil)
Hydrin P-7) 30% by weight liquid
0.42 parts were mixed to obtain a protective layer liquid A.

Seidan plate Kaimuri silica-modified polyvinyl alcohol (PVA made 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% by weight aqueous solution
0.42 parts Paraffin wax (Cellosol D-130 manufactured by Middle East Yushi ■) 22% by weight aqueous solution 0.5
4 parts titanium oxide (Tiebake A-10 manufactured by Ishihara Sangyo ■)
0) 1.9 parts of 33-layer heavy water dispersion were mixed to obtain 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 amount was 6 g/pot.

Next, as an intermediate layer, a 1% aqueous solution of sodium alginate (Snow Algin SH manufactured by Fuji Chemical Co., Ltd.) was applied in a dry coating amount of Ig/
It was applied so that mz was obtained.

Add 6 parts to the capsule solution and coupler/salt fin dispersion A5.5.
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 preservation F&layer solution B was applied so that the dry coating amount was 2 g/m''.

On the other side of the above coating layer, capsule 't&C5
, 0 parts of color developer dispersion A and 10.0 parts of color developer dispersion A were applied to a dry coating amount of 6 g/m'', and then protective layer liquid A was applied to a dry coating amount of 2 g/m''. A recording sheet was obtained.

The coating was done using a wire bar and then dried in an oven at 50°C.

After thermally printing the obtained recording sheet from the protective layer B liquid side with low energy (thermal head voltage 13V, printing time 0-2.5m5ec), Riff Piece-Pardry 1
The diazo coloring layer was fixed by irradiation with light for 10 seconds using Type 00.

Thereafter, thermal printing was performed using a higher energy than the above printing energy (thermal head voltage 18V, printing time 2.5
+-5m5 e c).

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

More liquid A? When thermal printing was performed with high energy from the J fabric side (thermal head voltage 15V printing time 0 to 5 m5ec), the color developed into magenta.

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

Further, even when this sheet was stored for a long time, there was no increase in fog or change in print density.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural diagram of a heat-sensitive recording material according to the present invention, which includes an opaque yellow coloring layer. FIG. 2 is a diagram showing the state of color development after the heat-sensitive recording material of FIG. 1 is exposed to light. l... Transparent support 2... Opaque magenta coloring layer 3... Transparent cyan coloring layer 4... Transparent protective layer 5... Opaque protective layer 6... Opaque Yellow colored layer

Claims (1)

[Scope of Claims] 1) One or more coloring unit layers capable of developing colors in different hues are provided on one side of a transparent support, and two or more phases capable of developing colors in different hues from any of the other surfaces are provided on the other side. This is a multicolor heat-sensitive recording material provided with a color-forming layer, in which an opaque protective layer is laminated on the outermost color-forming unit layer on one side, and a transparent protective layer is laminated on the color-forming unit layer provided on the opposite side. 1. A multicolor heat-sensitive recording material, characterized in that it has a structure in which a multicolor reflective image can be seen from the side of the transparent protection layer. 2) The multicolor thermosensitive recording according to claim 1, wherein all the color forming unit layers are substantially transparent except that the outermost color forming unit layer on the side provided with the opaque protective layer is an opaque color forming unit layer. material.