JPH01301282A - Multi-color recording medium - Google Patents

Abstract

PURPOSE:To prevent materials of color forming layers from migrating between the layers, by a method wherein a layer obtained by causing a water-soluble polyanion polymer to gel with a polyvalent cation is used between the laminated color forming layers as an intermediate layer. CONSTITUTION:In a multi-color recording medium formed by laminating two or more thermally color-forming unit layers containing a basic dye precursor and a color developer as color forming ingredients so as to produce hues different from each other on one surface of a substrate, an intermediate layer obtained by causing a water-soluble polyanion polymer to gel with a polyvalent cation is formed between the color forming layers. As the water-soluble polyanion polymer, a polymer having carboxyl group, sulfonic group, or phosphoric group is preferably used, and especially a water-soluble polyanion polymer having carboxyl group is desirable. In this manner, an undesirable layer-to- layer migration of materials of the respective layers can be prevented, and color reproducibility, image shelf stability, and the like can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multicolor recording material, and particularly to a multicolor recording material that can be thermally recorded with good color separation.

(Prior Art) As the most common method for obtaining multicolor images, silver halide photography has been widely put into practical use because of its high sensitivity, high image quality, and rich gradation reproducibility. However, silver halide photography has the drawback that the process is complicated because it processes the image with a developer after exposure and then converts the remaining silver halide into water-soluble silver complex salts or light-stable silver salts. have.

On the other hand, as a conventional method using a simple heat-sensitive recording method, for example,
No. 9, No. 52-11231, JP-A-54-88135
No. 55-133991, No. 55-133992, etc., a method is known 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. However, in addition, for example, Japanese Patent Publications No. 50-17868, No. 51-5791, No. 57
-14318, 57-14319, JP-A-55-
As shown in No. 161688, there is a color-erasing a structure 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 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 it has not been possible to overcome this deficiency in the past. That is, for example, when trying to increase the number of color hues, it is simply necessary to increase the number of fractions of the applied heating energy and widen the energy difference between them, so that the corresponding heat-sensitive coloring layers can be placed on the same support. It would be possible to design a heat-sensitive recording material having multiple heat-sensitive recording materials on the top, but in reality, if the applied heating energy is extended to a region where it is lower than before, problems will arise in terms of storage stability (so-called fog) of the recording material itself. On the other hand, when the applied heating energy is extended to a high region,
Serious new problems arise in terms of scorching of images, poor print runnability (for example, sticking) due to fusion, 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.

Furthermore, in JP-A No. 60-4092, there is a description that each component is dissolved and applied in the same layer in order to improve the transparency of the heat-sensitive coloring layer and improve color reproduction, but in this case, Since color development of each component easily occurs even before printing, so-called fogging occurs. Therefore, in any case, the above-mentioned known techniques have a small number of possible color divisions, and are essentially unsatisfactory as multicolor recording materials.

The inventors of the present invention have made extensive studies to solve the drawbacks of the conventional technology, and have found that by providing color-forming layers on both sides of a transparent support that are substantially transparent and that develop colors in different hues, the present inventors have improved the conventional method (good). It has been discovered that it is possible to obtain thermosensitive colored images, and has already been proposed (Japanese Patent Application No. 7, 1987, 5409).

(Problem to be Solved by the Invention) However, in a recording material that has a multi-color recording material mechanism by providing recording layers in layers, it is important to prevent the inconvenient movement of the material in each layer to improve color reproducibility and image quality. It is fundamentally important from the perspective of preservation, etc.

As a result of intensive studies aimed at improving from this perspective, the present inventors obtained extremely good results by using a layer made of a water-soluble polyanionic polymer gelled with polyvalent cations as an intermediate layer between the laminated coloring layers. The present invention was achieved by discovering that this can be done.

Accordingly, a first object of the present invention is to provide a recording material capable of obtaining multicolor images with high color density and little fog.

A second object of the present invention is to provide a multicolor recording material in which at least two recording layers, each of which develops a different hue through a color reaction, are provided on one side of a support in a layered manner, in which the material between each color development layer is The purpose is to provide an intermediate layer suitable for preventing movement between the eyebrows.

(Means for Solving the Problems) The above-mentioned aspects of the present invention are such that one side of the support contains a basic dye precursor and a color developer as color forming components, and two colors can be formed into different hues. In the multicolor recording material formed by laminating the above thermochromic unit layers, an intermediate layer formed by gelling a water-soluble polyanionic polymer with polyvalent cations is provided between the coloring layers. Achieved by color recording materials.

As the basic dye precursor used in the present invention, a colorless or light-colored one is appropriately selected from known compounds that develop color by donating electrons or accepting protons such as acids. Such compounds have partial skeletons such as lactones, lactams, sultones, spiropyrans, esters, and amides, and these partial skeletons are ring-opened or cleaved upon contact with a color developer. Preferred compounds include Examples include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran compounds.

Particularly preferred compounds are those represented by the following general formula.

In the formula, R5 is an alkyl group having 1 to 8 carbon atoms, R2 is an alkyl group having 4 to 18 carbon atoms, an alkoxyalkyl group, or a tetrahydrofurfuryl group, and R1 is a hydrogen atom or an alkyl group having 1 to 15 carbon atoms. Alternatively, the halogen atom and R4 represent a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.

As the substituent for R1, an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a halogenated alkyl group, and a halogen atom are preferable.

In the present invention, by encapsulating the above-mentioned coloring agent in microcapsules, it is possible to prevent fogging during the production of heat-sensitive recording materials, and at the same time, to improve the raw and record storage properties of the leisurely recording materials. can. In this case, by selecting the wall material and manufacturing method of the microcapsules, it is possible to increase the image density during recording. The amount of coloring agent used is preferably 0.05 to 5.0 g/rd.

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-51-222716.

Here, the organic solvent for forming oil droplets is -1
It can be appropriately selected from those used as pressure-sensitive oils in G.

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

In the present invention, the wall material of the microcapsule is selected,
If necessary, a glass transition point adjusting agent (for example, Japanese patent application 1986-
119862) to prepare microcapsules consisting of walls with different glass transition points, and by selecting combinations of basic colorless dye precursors with different hues and their color developers. It is possible to achieve intermediate colors. Therefore, the present invention is not limited to monochrome thermal paper, but can also be applied to two-color or multi-color thermal paper and thermal paper suitable for recording images with gradation.

In addition, if necessary, for example, Japanese Patent Application Laid-open Nos. 61-283589 and 61. A photofading inhibitor described in Japanese Patent No. 283590 and Japanese Patent No. 61-283591 can be added as appropriate.

As a color developer that causes a color-forming reaction when heated and melted with the basic colorless dye used in the present invention, any known color developer can be used as appropriate. For example, color developers for leuco dyes include phenolic compounds, sulfur-containing phenolic compounds, carboxylic acid compounds, sulfone compounds, urea or thiourea compounds, etc. Times (19B5) 49-54
and pages 65-70. Among these, those with a melting point of 50°C to 250'C are particularly preferred;
Among them, water-soluble phenols and organic acids at 60°C to 200°C are preferable, and when two or more color developers are used in combination, solubility increases, so it is preferable.

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

CI) c, +12. . lm=0～
2, n=2~11 (II) \HR? is an alkyl group, an aryl group, an aryloxyalkyl group or an aralkyl group, with methyl, ethyl and butyl groups being particularly preferred.

(III) R9 R1' is an alkyl group, particularly preferably a butyl group, a pentyl group, a heptyl group, and an octyl group.

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

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

In the present invention, a color developer is dissolved in an organic solvent that is sparingly soluble or insoluble in water, and then mixed with an aqueous phase containing a surfactant and having a water-soluble polymer as a protective colloid to emulsify and disperse it. It can also be used in the form of a dispersion.

The organic solvent that dissolves the color developer can be appropriately translated from organic solvents that are sparingly soluble or insoluble in water, but in particular,
It is preferable to use an organic solvent with a boiling point of 150° C. or higher, and it is particularly preferable to use esters from the viewpoint of stability of the color developer emulsion dispersion. Other preferred oils include compounds represented by the following general formulas (V) to (■), triallylmethane (e.g. tritolylmethane, tolyldiphenylmethane), terphenyl compounds (e.g. Eva, terphenyl), Alkylated diphenyl ether (
Examples include propyl diphenyl ether, hydrogenated terphenyl (eg, hexahydro terphenyl), diphenyl ether, and the like.

// ~ \ (V) In the formula, R' represents hydrogen or an alkyl group having a carbon number of 1 to 18, and Bz represents an alkyl group having 1 to 18 carbon atoms. p'
, q' represents an integer of 1 to 4, and the total number of alkyl groups is 4 or less.

Note that the alkyl groups for R' and R'' are preferably alkyl groups having 1 to 8 carbon atoms.

(VT) (R')P''(R')(1'' In the formula, R3 is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, R4 is an alkyl group having 1 to 12 carbon atoms, and 0 is 1 or 2. represent.

R2 and q2 represent integers of 1 to 4. When n=1, the total number of alkyl groups is 4 or less, and when n=2, the total number of alkyl groups is 6 or less.

(■) In the formula, Rs and Rb are a hydrogen atom or a carbon number of 1 to 18,
Represents the same or different alkyl groups.

m represents an integer from 1 to 13 p 2 and q 3 represent 1 to 13
represents an integer of 3, and the total number of alkyl groups is 3 or less.

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

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

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

Examples of compounds represented by 2 (■) include ■-methyl-1-dimethylphenyl-1-phenylmethane, l-ethyl-1-dimethylphenyl-1-phenylmethane, and ■-
Examples include propyl-1-dimethylphenyl-1-phenylmethane.

Examples of high-boiling esters with a boiling point of 150°C or higher include phosphoric esters (e.g., triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate, talesyl diphenyl phosphate), phthalic esters (dibutyl phthalate, -2 phthalate). -Ethylhexyl, ethyl phthalate, octyl phthalate, butyl benzyl phthalate) dioctyl tetrahydrofucrate, benzoate ester (ethyl benzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, benzyl benzoate), abietate ester (
ethyl abietate, benzyl abietate), dioctyl adipate, isodecyl succinate, dioctyl azelate, oxalate esters (dibutyl oxalate, dipentyl oxalate), diethyl malonate, maleate esters (dimethyl maleate, diethyl maleate, dibutyl maleate), tributyl citrate, sorbate esters (methyl sorbate, ethyl sorbate, butyl sorbate), sebacate esters (dibutyl sebacate, dioctyl sebacate), ethylene glycol esters (formic acid monoesters and diesters, acetic acid monoesters and diesters, lauric acid monoesters and diesters, valmitic 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. Among these, when tricresyl phosphate is used in combination, the emulsion dispersion stability of the color developer is particularly good and is therefore preferred.

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

In the present invention, in addition to the above-mentioned oils, an organic solvent having a boiling point of 150° C. or less can be used as an auxiliary solvent. Examples of such organic 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.

Furthermore, as the surfactant to be contained in the aqueous phase, it is possible to appropriately select and use an anionic or nonionic surfactant that does not interact with the protective colloid to cause precipitation or aggregation. can.

Preferred surfactants include sodium alkylbenzenesulfonate (e.g., sodium dodecylbenzenesulfonate), sodium alkylsulfate, dioctyl sodium sulfosuccinate, polyalkylene glycol (e.g., 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.

A melting point depressant for a color developer may be added to this emulsified dispersion as appropriate. Some of these melting point depressants are
It also functions as a glass transition point regulator for the capsule wall. Examples of such compounds include hydroxy compounds, carbamate ester compounds, sulfonamide compounds, aromatic methoxy compounds, etc. For details, see
For example, it is described in Japanese Patent Application No. 59-244190.

These melting point depressants can be used in an amount of O,] to 2 parts by weight, preferably 0.5 to 1 part by weight, per 1 part by weight of the color developer that lowers the melting point. It is preferable that the melting point depressant and the color developer and the like that lower the melting point are used at the same location. When adding to different locations, it is preferable to add 1 to 3 times the above amount.

The color-forming material of the present invention can be coated using a suitable binder.

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

In the present invention, it is essential to provide an intermediate layer between the coloring layers, but in the present invention, as this intermediate layer,
In particular, a layer formed by gelling a water-soluble polyanionic polymer with polyvalent cations is used.

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 polysaccharide gums (such as alkali metal alginates, guar gum, gum arabic, carrageenan, pectin, gum tragacanth, gum xanthine, etc.), gums of acrylic acid or methacrylic acid, etc. Polymers and copolymers thereof, maleic acid or phthalic acid polymers and copolymers thereof, cellulose derivatives such as carboxymethyl cellulose, gelatin, agar, etc.
Among them, alginate alkali metal salts are preferred. The molecular weight of the water-soluble polyanionic polymer is 5,000 to 10,0
00 is preferable, especially from the viewpoint of barrier properties and manufacturing suitability aimed at in the present invention], 0.000 to 40.0
00 is preferred. Examples of polyvalent cations include salts of alkaline earth metals and other polyvalent metals (e.g. CaCl2, BaC
Preferred are e, , Afz (S(L), , ZnSO4, etc.), polyamines (eg, ethylenediamine, diethylenetriamine, hexamethylenediamine, etc.), and polyimines.

Other preferred examples of intermediate layers in the present invention include ionic combinations of water-soluble polyanionic polymers and water-soluble polycationic polymers. In this case, the various water-soluble polyanionic polymers described above can be used as the water-soluble polyanionic polymer.

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

When producing the intermediate layer using these material zero 4,
In order to prevent rapid gelation during coating, it is preferable to include one of the materials in the first coloring layer or the second coloring layer. It is also possible to contain one material in one coloring layer and the other material in a second coloring layer.

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

In the present invention, a white pigment may be added to the coloring layer or intermediate layer for the purpose of preventing fog or increasing whiteness, or a layer containing a white pigment may be additionally coated.

Examples of preferred white pigments include talc, calcium carbonate, calcium sulfate, magnesium carbonate, magnesium hydroxide, alumina, synthetic silica, titanium oxide, barium sulfate, kaolin, calcium silicate, urea resin, and the like.

Furthermore, it is also possible to provide a protective layer on the top layer.

HogI I? i is polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, methylcellulose,
Water-soluble polymers such as ethyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose to which pigments, metal soaps, wax, crosslinking agents, etc. are added are used.

Pigments include zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, Rouseki, kaolin, aluminum hydroxide, amorphous silica, etc., and the amount added is 0.05 to 2.0% of the total weight of the polymer. times, particularly preferably 0
．． It is 1 to 5 times the amount.

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

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

For more information on the protective layer, please see Gi Pulp Technology Times N
o, 8 (1985).

Furthermore, an undercoat layer may be provided for the purpose of increasing the adhesion between the support and the coloring layer, improving smoothness, and providing heat insulation.

As the material for the undercoat layer, water-soluble polymers such as gelatin, synthetic polymer latex, nitrocellulose, etc. are used. The coating amount of the undercoat layer is preferably in the range of 0.1 g/m to 2.0 g/rrf, particularly 0.2 g/rrr to
1. A range of Og/rtT is preferred.

Examples of the support used in the present invention include paper, synthetic paper, and polymer film.

In the present invention, the paper used for the support is a neutral paper with a heat extraction pH of 6 to 9 sized with a neutral sizing agent such as an alkyl ketene dimer (Japanese Patent Laid-Open No. 55-1428
The use of the product described in No. 1) is advantageous in terms of storage stability over time.

In order to prevent the coating liquid from penetrating into paper,
As described in No. 687.

In addition, paper having an optical surface roughness of 8μ or less and a thickness of 40 to 75μ described in JP-A-58-136492, JP-A-58-136492,
Paper with a density of 0°9 g/cn or less and an optical contact ratio of 15% or more as described in No. 8-69097, JP-A-58-6909
Canadian standard freeness described in No. 7 (JIS P8121
) Paper made from valves beaten to 400 cc or more to prevent penetration of coating liquid, JP-A-58-65695
JP-A-59-35985 describes a method in which the glossy side of a base paper made by a Yankee machine is used as the coated surface to improve color density and resolution, and a method in which the base paper is subjected to corona discharge treatment as described in JP-A-59-35985. Papers with improved coating suitability may also be used in the present invention with good results. In addition to these, any support commonly used in the field of heat-sensitive recording paper can be used as the support of the present invention.

In the present invention, a back layer may be provided on the back surface of the support for the purpose of curl correction, antistatic properties, and improved slipperiness. As the constituent components of the back layer, it is preferable to use the same components as those of the protective layer.

Among the supports used in the present invention, polymer films include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate films, polystyrene films, polypropylene films, and polyolefin films such as polyethylene. , these can be used alone or in combination.

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

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. 2.94L 898, and No. 3゜526
．． Specification No. 528, "Coating Engineering 32" by Yuji Harasaki
It is also possible to apply the coating simultaneously in two or more layers using the method described in p. .

Adding pigment dispersants, thickeners, flow modifiers, antifoaming agents, foam inhibitors, mold release agents, colorants, surfactants, etc. to the coating liquid used in the present invention can be carried out as necessary. There is nothing wrong with it as long as it does not damage its characteristics.

When carrying out the present invention, the number of coloring layers is not limited to two, and a plurality of layers can be further provided thereon. In this case, coloring layers with different coloring hues are usually provided.

It is also possible to provide coloring layers on both sides of the support.

(Example) The following compound (CIBAPer
gascript Blue) C8Hl, + 20 g each of bisphenol A as a color developer and β-naphthylbenzyl ether as a sensitizer were dispersed with 100 g of a 5% polyvinyl alcohol (PVA-105 manufactured by Kuraray ■) aqueous solution using a ball mill day and night. The volume average particle diameter was set to 3 μm or less.

Calcium carbonate (Unjbur70: manufactured by Shiraishi Kogyo ■) was used as the pigment, and 80g was mixed with 0% sodium hexametaphosphate.
．． Each dispersion prepared as above was used by dispersing with 160 g of 5% aqueous solution using a homogenizer.
Anilino-3-methyl-N-methyl-N-cyclohexylaminofluorane dispersion 5g, bisphenol A dispersion 10g, β-naphthylbenzyl ether molecule lt11
A heat-sensitive dispersion liquid A was obtained by mixing at a ratio of 5 g.

Ky11 Koka produced silica-modified polyvinyl alcohol (PVA made by Kuraray)
R2105) 10% liquid 10 parts Colloidal silica (Snowtex 30 manufactured by Nissan Chemical ■) 30
Jukei% liquid 5 parts Zinc stearate (Hydrin 2-7 manufactured by Chukyo Yushi ■) 30% by weight liquid
0.42 parts Paraffin wax (Hydrin P-7 manufactured by Tokyo Yushi Corporation) 30% by weight liquid 0.4
Two parts were mixed to obtain a protective layer solution A.

The following compound (CIBAPe) was used as a hard basic dye precursor.
rgascript Red l-6-8)
14 parts a HI7 1-phenyl-1-xylylethane 55 parts Methylene chloride 55 parts Sumithorpe 200
(Ultraviolet absorber manufactured by Sumitomo Chemical @) 2 parts Takenate D-11ON (manufactured by Takeda Pharmaceutical Company Ltd., trade name) 60 parts mixed, 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol and 4 parts distilled water
After adding it to an aqueous solution consisting of 0 parts, it was emulsified and dispersed 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 a capsule liquid. 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 1-F22R! -Dissolved in 8 parts of xylylethane and 30 parts of ethyl acetate. The obtained developer solution was mixed with 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol, 150 parts of water, and 0.00 parts of sodium dodecylbenzenesulfonate.
Mix with 5 parts of aqueous solution and emulsify and disperse, particle size 0.5
Obtain an emulsified dispersion of μ＼/−”′− １＼１、Color developer (al) Color developer (b) Color developer (C) Dry coating on high-quality paper with a weight of 50 g/rrf After applying heat-sensitive dispersion A in an amount of 6 g/pot, add 3% sodium alginate (Snow Algin SH manufactured by Fuji Chemical) as an intermediate layer.
The dry coating amount of the aqueous solution is 0. It was coated at a concentration of 5 g/rrf.

Next, a mixed solution of 5.0 parts of capsule liquid, 10 parts of color developer dispersion, and 0.5 part of 10% by weight aqueous calcium chloride solution was applied so that the dry coating amount was 6 g/bo, and then the protective layer liquid was dried. A recording sheet was obtained by coating at a coating amount of 2 g/rtr. The coating was done using a wire bar and then dried in an oven at 50°C.

The obtained recording sheet was thermally printed with low energy (thermal head voltage 15V, printing time 0 to 2.5 m5ec) and high energy compared to the above printing energy (thermal head voltage 15V, printing time 2.5 to 2.5 m5ec). 5ms e c)
It was thermally printed.

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

Further, this sheet showed no increase in fog or change in print density even after being stored for a long time.

Comparative Example 1 A recording sheet was obtained in exactly the same manner as in Example 1, except that no intermediate layer was provided.

When the obtained sheet was colored in the same manner as in Example 1, the red of the low energy printing and the blue of the lower layer were mixed, resulting in a muddy red color.

Also, when stored for a long time, black fogging was observed.

Claims (1)

[Claims] 1) One side of the support contains a basic dye precursor and a color developer as coloring components, and can be colored in different hues.2
In the multicolor recording material formed by laminating the above thermochromic unit layers, an intermediate layer formed by gelling a water-soluble polyanionic polymer with polyvalent cations is provided between the coloring layers. Color recording material.