JP2777141B2 - Two-color thermal recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-color heat-sensitive recording medium having a plurality of color-forming layers each of which develops a different color tone.

"Prior art" Conventionally, a thermosensitive recording in which a color-forming image is obtained by contacting both color-forming substances by heat using a color-forming reaction between a color-forming agent and a color-forming agent that forms a color in contact with the color-forming agent. The body is well known. Such a thermosensitive recording medium is relatively inexpensive, and its recording equipment is compact and its maintenance is relatively easy. Therefore, it is used not only as a recording medium for facsimile machines and various computers but also in a wide range of fields.

However, the required performance and quality are diversified with the expansion of applications, and for example, high sensitivity, image stabilization, multicolor recording, and the like are mentioned. In particular, since multicolor recording has a wide range of applications, many recording materials have been researched and proposed to date.

Conventional two-color recording materials are roughly classified into the following two types. The first is to make the low-temperature thermosensitive coloring layer develop at the time of low-temperature heating,
During heating at a high temperature, both the low-temperature heat-sensitive coloring layer and the high-temperature heat-sensitive coloring layer are colored to obtain a mixed color. The other is a method of obtaining the color tone of the high-temperature thermosensitive coloring layer at the time of high-temperature heating by using a decoloring agent having a decoloring effect on the color-forming system of low-temperature coloring at the time of high-temperature heating in the first method.

In the first method, an image becomes unclear due to color mixing and blurring occurs. Therefore, the second method is generally suitable as a method for obtaining an image of two colors. In the second method, various decoloring agents having a decoloring effect on a color forming system composed of a basic leuco dye and an organic acidic substance have been proposed. However, in a two-color heat-sensitive recording medium in which the intermediate layer containing these decoloring agents is provided directly in contact with the low-temperature coloring layer, the decoloring agent affects the low-temperature coloring layer, and the unrecorded portion or the recorded portion is not affected. There is a defect that storage stability deteriorates.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems in a two-color heat-sensitive recording medium provided with an intermediate layer containing a decoloring agent, and has a clear recording sensitivity with good color mixing and little bleeding. An object of the present invention is to provide a two-color heat-sensitive recording medium capable of forming an image having a natural color tone.

"Means for Solving the Problems" The object as described above of the present invention is that at least a high-temperature coloring layer, an intermediate layer containing a decoloring agent, and a low-temperature coloring layer are sequentially laminated on a support, and the coloring layer is In a two-color thermosensitive recording medium that is a leuco-based coloring layer containing a leuco dye and a coloring agent, a phenolic compound having a melting point of 170 ° C. or more is used as the coloring agent of the low-temperature coloring layer, and Melting point is 90-16 for 1 part by weight of phenolic compound having a melting point of 170 ° C or higher.
It is achieved by incorporating 0.2 to 2 parts by weight of a monophenolic compound or a diphenolic compound at 0 ° C.

"Function" As described above, the two-color heat-sensitive recording material of the present invention uses a phenolic compound having a high melting point as a coloring agent for the low-temperature coloring layer, and uses a phenolic compound having a relatively low melting point in combination with the phenolic compound. However, it has important features.

By using a phenolic compound having a high melting point as a colorant, the effect of the decoloring agent is reduced even under high-temperature and high-humidity conditions, and storage stability has been improved, but when recording using a thermal head, It was confirmed that some insoluble parts remained, and that sticking to the head and sticking occurred. Therefore, the improvement was attempted by adding a lubricant such as wax, but the wax was not sufficiently compatible with the colorant at the time of hot melting, or a satisfactory effect was not obtained. When blended in such a large amount that
It was clarified that the coating amount was increased and as a result, the recording sensitivity of the high-temperature coloring layer was lowered, and that a defect that the recorded image was unclear was accompanied.

Therefore, as a result of further intensive studies, it was found that the melting point of the phenolic compound having a melting point of 170 ° C. or more was 90 to 160 parts by weight.
When 0.2 to 2 parts by weight of a monophenolic compound or a diphenolic compound having a relatively low melting point of 0 ° C. is used in combination, these compounds have a structure similar to that of a colorant,
The present invention was found to be excellent in compatibility with the coloring agent, and as a result, wasted that the adhesion of dregs to the head and the sticking phenomenon were eliminated while maintaining the excellent effect of improving the storage stability, and completed the present invention. .

Thus, the melting point used as a low-temperature hue coloring agent is
Specific examples of the phenolic compound at 170 ° C. or higher include, for example, 4,4′-cyclohexylidenediphenol (mp180
° C), resorcinol monobenzyl ether (mp181
° C), bis (4-hydroxyphenyl) sulfone [bisphenol S] (mp248 ° C), 2,4'-bisphenol (mp183 ° C), bis (2,5-dimethyl-4-hydroxyphenyl) sulfide (mp189 ° C), 2,4-dimethyl-
2,4,6-tris (4-hydroxyphenyl) heptane (mp 202 ° C.) and the like are of course not limited to these. In addition, among these coloring agents, 4,
4'-Cyclohexylidenediphenol is preferably used because it gives a recorded image with a particularly high density.

In the present invention, the melting point used in combination with the color former as described above is
Examples of the monophenolic compound or diphenolic compound at 90 to 160 ° C include 4-tert-butylphenol, 4-hydroxydiphenoxide, 4-hydroxyacetophenone, 4-tert-octylcatechol, 4-phenylphenol, and hydroquinone monobenzyl Ether, benzyl-4-hydroxyacetate, 4-hydroxyphthalic acid dimethyl ester, 4-hydroxyphthalic acid diethyl ester, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid-n-propyl ester, 4-hydroxybenzoic acid- n-butyl ester, 4
-Hydroxybenzoic acid isobutyl ester, 4-hydroxybenzoic acid benzyl ester, 4-hydroxybenzoic acid-p-chlorobenzyl ester, 4-hydroxybenzoic acid-o-chlorobenzyl ester, 4-hydroxybenzoic acid-p-methylbenzyl ester 4-hydroxy-4'-methoxydiphenylsulfone, 4-hydroxy-4'-ethoxydiphenylsulfone, 4-hydroxy-4'-n-propoxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone,
-Hydroxy-4'-butoxydiphenyl sulfone, 4
-Hydroxy-4'-pentyloxydiphenylsulfone, 4-hydroxy-4'-hexyloxydiphenylsulfone, 4-hydroxy-4'-heptyloxydiphenylsulfone, 4-hydroxy-4'-octyloxydiphenylsulfone, 4-hydroxy -4'-nonyloxydiphenyl sulfone, 4-hydroxy-4'-n
-Decyloxydiphenyl sulfone, 4-hydroxy-
4'-benzyloxydiphenylsulfone, 4-hydroxy-4'-phenyloxydiphenylsulfone, 2,
2'-dihydroxydiphenyl, 2,2'-methylenebis (4-methyl-6-tert-isobutylphenol), 2,
2'-methylenebis (4-chlorophenol), 4,4'-
Isopropylidene diphenol [bisphenol A],
4,4'-isopropylidenebis (3-chlorophenol), 4,4'-isopropylidenebis (3-isopropylphenol), 4,4'-isopropylidenebis (2-t
ert-butylphenol), 4,4'-sec-butylidenediphenol, and the like, but are not limited to these compounds.

In addition, among these phenolic compounds, 4,4 ′
-Isopropylidenediphenol, 4-hydroxybenzoic acid benzyl ester and 4-hydroxy-4'-isopropoxydiphenylsulfone are more preferably used in combination with a high-melting-point colorant, in particular, to give a recording medium with less background fog. Can be

The phenolic compound having a relatively low melting point as described above is a phenolic compound having a high melting point used as a coloring agent.
0.2 to 2 parts by weight, more preferably 0.2 to 1 part by weight,
They are used together in a range of about parts by weight.

The color-forming layer constituting the recording medium of the present invention is a leuco-based color-forming layer containing a leuco dye and a color former, and various useful colorless to light-colored basic dyes are known. , 3-bis (p-dimethylaminophenyl)
-6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindole-3
-Yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl)
-5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -6 -Dimethylaminophthalide, 3,3-bis (2-
Phenylindol-3-yl) -6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1
-Methylpyrrole-3-yl) -6-dimethylaminophthalide and other triallylmethane dyes, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucouramine, N-2, Diphenylmethane dyes such as 4,5-trichlorophenyl leuco auramine, thiazine dyes such as benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue;
Methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (6'-methoxybenzo) spiropyran, 3-propyl-spiro Lactam dyes such as spiro dyes such as dibenzopyran, rhodamine-B anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o-chloroanilino) lactam, 3-cyclohexylamino-6-chlorofluoran, 3- Dimethylamino-7-methoxyfluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7
-Methoxyfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-
Chlorofluorane, 3-diethylamino-7,8-benzofluoran, 3-diethylamino-5-methyl-7-dibenzylaminofluoran, 3-diethylamino-6,7
-Dimethylfluoran, 3- (N-ethyl-p-toluidino) -7-methylfluorane, 3-diethylamino-
7-N-acetyl-N-methylaminofluoran, 3-
Diethylamino-7-N-methylaminofluoran, 3
-Diethylamino-7-dibenzylaminofluoran,
3-diethylamino-7-N-methyl-N-benzylaminofluoran, 3-diethylamino-7-N-chloroethyl-N-methylaminofluoran, 3-diethylamino-7-N-diethylaminofluoran, 3- (N −
Ethyl-p-toluidino) -6-methyl-7-phenylaminofluoran, 3- (N-cyclopentyl-N-ethylamino) -6-methyl-7-anilinofluoran,
3- (N-ethyl-p-toluidino) -6-methyl-7
-(P-toluidino) fluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3-diethylamino-7- (2-carbomethoxy-phenylamino) fluoran, 3- (N-ethyl-N-isoamyl Amino) -6-methyl-7-phenylaminofluoran, 3- (N-cyclohexyl-N-methylamino)-
6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-phenylaminofluoran,
3-piperidino-6-methyl-7-phenylaminofluoran, 3-diethylamino-6-methyl-7-xylidinofluoran, 3-diethylamino-7- (o-chlorophenylamino) fluoran, 3-dibutylamino-
7- (o-chlorophenylamino) fluoran, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluoran, 3-N-methyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofur Oran, 3
-N-ethyl-N-tetrahydrofurfurylamino-6
And fluoran-based dyes such as -methyl-7-anilinofluoran.

The use ratio of the basic dye and the colorant is preferably 1 to 30 parts by weight, preferably about 1 to 8 parts by weight, based on 1 part by weight of the basic dye in the low-temperature coloring layer, In the high-temperature coloring layer, the coloring agent is added in an amount of 1 to 1 part by weight of the basic dye.
It is desirable to use 50 parts by weight, preferably about 2 to 10 parts by weight.

As the coloring agent used in the high-temperature coloring layer, various inorganic or organic acidic substances are known. In addition to the coloring agent used in the low-temperature coloring layer, for example, activated clay, acid clay, attapulgite, bentonite , Colloidal silica, inorganic acidic substances such as aluminum silicate, α-naphthol, β-naphthol, phenolic compounds such as novolak phenolic resins, phenolic polymers, benzoic acid, p
-Tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid,
3-cyclohexyl-4-hydroxybenzoic acid, 3,5-
Dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-
Isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3-benzylsalicylic acid, 3- (α-methylbenzyl) salicylic acid, 3-chloro-5- (α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid,
Aromatic carboxylic acids such as 3-phenyl-5- (α, α-dimethylbenzyl) salicylic acid and 3,5-di-α-methylbenzylsalicylic acid, and these phenolic compounds; aromatic carboxylic acids and zinc, magnesium, Examples thereof include organic acidic substances such as salts with polyvalent metals such as aluminum, calcium, titanium, manganese, tin and nickel.

In the coating liquid for forming the color-forming layer, as an adhesive component, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin,
Casein, gum arabic, polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, natural rubber Emulsions, styrene / butadiene copolymer emulsions, acrylonitrile / butadiene copolymer emulsions, methyl methacrylate / butadiene copolymer emulsions, polychloroprene emulsions, vinyl acetate emulsions, ethylene / vinyl acetate emulsions and the like are added. Further, as a pigment component, for example, diatomaceous earth, calcined diatomaceous earth, kaolin, calcined kaolin, white carbon,
Inorganic pigments such as magnesium carbonate, calcium carbonate, zinc oxide, ammonium oxide, titanium oxide, silicon oxide, aluminum hydroxide, barium sulfate, zinc sulfate, talc, clay, calcined clay, styrene microballs, nylon powder, polyethylene powder, urea -Formalin resin filler, organic pigments such as raw starch granules are added,
Of course, the present invention is not limited to these exemplified substances, and two or more of them can be used in combination as needed.

Various other auxiliaries can be added to the coloring layer coating solution, for example, sodium dioctyl sulfosuccinate,
Sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, alginate,
Examples thereof include dispersants such as resin acid metal salts, benzophenone-based and triazole-based ultraviolet absorbers, defoamers, fluorescent dyes, and coloring dyes.

Further, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, etc., fatty acid amides such as stearic amide, stearic acid methylene bisamide, oleic amide, palmitic amide, coco fatty acid amide, Benzyl terephthalate, 1,2-di (3
-Methylphenoxy) ethane, 1,2-diphenoxyethane, 4,4'-ethylenedioxy-bis-benzoic acid diphenylmethyl ester, and various known heat-fusible substances can also be used in combination.

In the heat-sensitive recording medium of the present invention, the coating amount of each coloring layer is not particularly limited, but it is generally applied so that the dry weight of the low-temperature or high-temperature coloring layer is about 1.5 to 12 g / m ² .

In the heat-sensitive recording medium of the present invention, the intermediate layer contains a decoloring agent as a main component. In addition, various adhesives, pigments, heat-fusible substances, and the like as described above are appropriately compounded. Further, the layer configuration of the intermediate layer is not limited to a single layer, and a decoloring layer mainly containing a decoloring agent and a layer mainly containing another material may be laminated in two or more layers.

The decoloring agent contained in the decoloring layer in the present invention is not particularly limited, aliphatic amines, piperidines, piperazines, pyridines, imidazoles,
Imidazolines, morpholines, guanidines, amidines, polyethers, glycols, aromatic amides and the like are preferably used.

Specifically, for example, the following compounds are described in various known documents. Alkylene oxide adduct of bisphenols (JP-A-54-139741) Ethylene oxide adduct of terephthalic acid (JP-A-55-25306) Long-chain 1,2
-Glycol (JP-A-55-27217) glycerin fatty acid ester (JP-A-55-113593) urea derivative (JP-A-55-139290) alkylene oxide adduct of linear glycol (JP-A-55-139290) JP-A-152094] Morpholine derivative [JP-A-56-40588] Solid alcohol [JP-B-50-17865] Polyether and polyethylene glycol derivatives [JP-B-50-17867, JP-B-50-17867]
No.-17868) nitrogen-containing crystalline organic compound (Japanese Patent Publication No. 51-1)
No. 9991] Guanidine derivative (JP-B-51-29024) amine or quaternary ammonium salt (JP-A-50-1804)
No. 8] disubstituted amide compounds of aliphatic and aromatic carboxylic acids [JP-A-60-120792] and the like.

Further, specific examples of amidines include, for example, N, N'-diphenylformamidine, N, N'-di-o-tolylformamidine, N, N'-diphenylbenzamidine, N-
N'-di-p-tolyl-N'-phenylbenzamidine, N, N ', N "-N-tetraphenyl-heptadiamidine, N, N', N", N-tetraphenyl-P-xylylenediamidine and the like And specific examples of piperidines include, for example, (2,2,6,6-tetramethyl-4-piperidyl / tridecyl) -1,2-ethanedicarboxylate, tetrakis (1,2,2,6, 6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1-methyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, Δ2,2 , 6,6-Tetramethyl-4-piperidyl / β, β, β ', β'-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl} -1,2,3,4-butanetetracarboxylate, {1,2,2,6,6-pentamethyl-4-piperidyl / β, β, β, β'- tetramethyl-3,9 [2,4,
8,10-tetraoxaspiro (5,5) undecane] diethyl {-1,2,3,4-butanetetracarboxylate, (1,
2,2,6,6-pentamethyl-4-piperidyl) -1-heptanecarboxylate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxy Rate and the like.

In addition, among these various decoloring agents, piperidines, amidines, and disubstituted amide compounds of aromatic carboxylic acids have a low degree of influence on the high-temperature coloring layer, and show an excellent decoloring effect on the low-temperature coloring layer. Therefore, it is particularly preferably used.

The above-described various decolorizing agents are generally contained in the decoloring layer in an amount of about 0.1 to 20 times by weight based on the total weight of the leuco dye and the color former in the low-temperature color-forming layer, but more preferably 0.5 to 6 times.
It is adjusted within the range of about weight times. It is of course possible to use two or more decoloring agents in combination.

In the coating liquid for forming the intermediate layer, various adhesives, dispersants, lubricants, heat-fusible substances, inorganic pigments, organic pigments, etc., as described in the description of the coloring layer coating liquid, and other defoaming Various auxiliaries such as an agent, an ultraviolet absorber, a fluorescent dye, and a coloring dye can be appropriately compounded. Further, as described above, the layer configuration of the intermediate layer is not limited to a single layer, and a decoloring layer containing a decoloring agent as a main component and a layer containing other materials as a main component may be laminated in two or more layers. In a preferred embodiment, a layer containing a decoloring agent as a main component and a layer containing a pigment as a main component are sequentially laminated, the pigment component of the layer containing a pigment as a main component is 50 to 90% by weight, and the coating amount is 1%. It is to be adjusted to a range of about 5 g / m ² . By adopting such a layer configuration, the storage stability of the low-temperature coloring layer is further remarkably improved, and the adhesion of scum to the thermal head during recording and the sticking phenomenon are effectively eliminated.

If necessary, a layer in which an adhesive, a heat-fusible substance, a pigment or the like is appropriately mixed may be formed between the low-temperature coloring layer or the high-temperature coloring layer and the decoloring layer.

In the heat-sensitive recording medium of the present invention, the coating solution for each color-forming layer or intermediate layer is generally prepared by using water as a dispersion medium and appropriately using a ball mill, an attritor, a sand mill, or the like, and a pulverizer. The method for forming each color-forming layer and the intermediate layer is not particularly limited, and is formed by a method of applying and drying a coating solution on a support by, for example, air knife coating, blade coating, or the like according to a conventionally known technique. .

The support is also not particularly limited, and papers such as high-quality paper, base paper made by a Yankee machine, single-side polished base paper, double-side polished base paper, cast coated paper, art paper, coated paper, medium-coated paper, and synthetic fibers Paper, synthetic resin film and the like are used as appropriate. Further, after applying and drying the color-forming layer, a smoothing treatment such as super calendering can be performed as necessary.

Furthermore, various variations are possible within a range not exceeding the gist of the present invention.For example, an overcoat layer is provided on the color-forming layer for the purpose of protecting the color-forming layer, or an undercoat layer or a backcoat layer is provided on the support. Various known techniques in the heat-sensitive recording medium field, such as the provision thereof, can be added. Also, the color-forming material and color tone constituting each color-forming layer can be variously varied, and can be appropriately selected according to the intended two-color thermosensitive recording medium.

The heat-sensitive recording material of the present invention thus obtained is a two-color heat-sensitive recording material having excellent recording sensitivity, being sufficiently adaptable to high-speed recording, and capable of forming a clear color tone image with little color mixing or bleeding.

"Examples" Examples are shown below to explain the present invention more specifically, but of course the present invention is not limited thereto. Unless otherwise specified, “parts” and “%” in the examples indicate “parts by weight” and “% by weight”, respectively.

Solution A preparation 3-Diethylamino-7-chlorofluoran 10 parts Methylcellulose 5% aqueous solution 5 parts Water 25 parts This composition was pulverized with a sand mill until the average particle diameter became 3 μm.

Preparation of Solution B 4,4'-Cyclohexylidenediphenol 40 parts Methylcellulose 5% aqueous solution 40 parts Water 80 parts This composition was pulverized with a sand mill until the average particle diameter became 3 μm.

Solution C preparation 4,4'-isopropylidene diphenol 40 parts Methyl cellulose 5% aqueous solution 40 parts Water 80 parts This composition was pulverized by a sand mill until the average particle diameter became 3 μm.

Solution D Preparation Tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate 40 parts Methylcellulol 5% aqueous solution 20 parts Water 60 parts This composition Was pulverized by a sandle mill until the average particle diameter became 3 μm.

Solution E Preparation 3- (N-ethyl-N-isoamylamino) -6-methyl-7-phenylaminofluoran 10 parts Dibenzyl terephthalate 30 parts Methylcellulose 5% aqueous solution 20 parts Water 100 parts Grinding was performed until the diameter became 3 μm.

Example 1 [Preparation of coating liquid for high-temperature heat-sensitive recording layer] 40 parts of liquid A, 160 parts of liquid B, 30 parts of silicon oxide pigment (trade name: Mizukasil-527, manufactured by Mizusawa Chemical Co., Ltd.), 20% aqueous starch oxide solution
100 parts and 70 parts of water were mixed and stirred to obtain a coating liquid.

(Preparation of decolorizing layer coating liquid)

Solution D 120 parts, 10% aqueous solution of polyvinyl alcohol 100 parts,
30 parts of water was mixed and stirred to obtain a coating liquid.

(Preparation of coating solution for barrier layer)

40 parts of silicon oxide pigment (trade name: Mizukasil P-527, manufactured by Mizusawa Chemical Co., Ltd.), 8 parts of 30% zinc stearate dispersion (trade name: Hydrin Z-7, manufactured by Chukyo Yushi Co., Ltd.), 10% aqueous solution of polyvinyl alcohol 75 And 127 parts of water were mixed and stirred to obtain a coating liquid.

(Preparation of coating liquid for low-temperature heat-sensitive recording layer)

160 parts of E liquid, 80 parts of B liquid, 20 parts of C liquid, 20 parts of silicon oxide pigment (trade name: Mizukasil P-527, manufactured by Mizusawa Chemical), 30% zinc stearate dispersion (trade name: Hydrin Z-7) 20 parts, 10% aqueous polyvinyl alcohol solution 100
And 100 parts of water were mixed and stirred to obtain a coating liquid.

(Formation of recording layer)

The high-quality paper having a basis weight 50 g / m ^2, the high-temperature heat sensitive recording layer coating solution, decolorizing layer coating solution, the barrier layer coating solution, a low-temperature heat-sensitive recording layer coating solution in this order, the coating amount after drying each ^{7g / m 2, 3g / m} 2, 2g
/ m ² , 3 g / m ² , drying and super calendar treatment to obtain a two-colored heat-sensitive recording paper.

Example 2 In preparing a coating solution for a low-temperature heat-sensitive recording layer, 80 parts of solution B and C
A two-color heat-sensitive recording paper was obtained in the same manner as in Example 1, except that 50 parts of the liquid B and 50 parts of the liquid C were used instead of 20 parts of the liquid.

Example 3 In preparing a coating solution for a low-temperature heat-sensitive recording layer, 80 parts of solution B and C
A two-color heat-sensitive recording paper was obtained in the same manner as in Example 1 except that 35 parts of the liquid B and 65 parts of the liquid C were used instead of 20 parts of the liquid.

Example 4 A two-colored heat-sensitive recording paper was obtained in the same manner as in Example 1 except that benzyl 4-hydroxybenzoate was used instead of 4,4'-isopropylidenediphenol in the preparation of Liquid C.

Example 5 A two-color heat-sensitive recording paper was prepared in the same manner as in Example 1 except that 4-hydroxy-4'-isopropoxydiphenylsulfone was used instead of 4-4'-isopropylidenediphenol in the preparation of Liquid C. I got

Comparative Example 1 In preparing a coating solution for a low-temperature heat-sensitive recording layer, 80 parts of solution B
A two-color heat-sensitive recording paper was obtained in the same manner as in Example 1 except that 100 parts of the liquid B was used instead of 20 parts of the liquid C.

Comparative Example 2 In preparing a coating solution for a low-temperature heat-sensitive recording layer, 80 parts of solution B and C
Example 1 except that 100 parts of liquid C was used instead of 20 parts of liquid
In the same manner as in the above, a two-color heat-sensitive recording paper was obtained.

The dynamic coloring performance of the thus obtained seven types of two-color coloring thermal recording paper was tested by the following method.

[Recording conditions]

Using a thermal printer (PS-8600, manufactured by ROHM),
Thermal head: 8 dots / mm, heating resistance: about 1300 ohm /
Dot, main scan recording speed: 20 msec / line, sub-scan: 32 line / m
m, head input: 0.44W / dot, low-temperature coloring energy: 0.26
The recording was performed under the conditions of mlJ and high-temperature coloring energy: 1.06 mJ, and the density of the recording portion was measured with a Macbeth densitometer (RD-914, manufactured by Macbeth), and the results are shown in the table. The density of the high-temperature coloring image (red) was measured using a green filter.

(Preservation of unrecorded part)

The unrecorded thermosensitive recording paper was left under the conditions of 40 ° C. and 90% RH for 24 hours, then recorded under the same conditions as above, and the recording density of the low-temperature coloring image was measured in the same manner. .

[Recording suitability]

Evaluation was made in a situation where the recording paper sticks to the thermal head. The sticking phenomenon to the head occurred in the recording paper of Comparative Example 1, but did not occur in other recording papers.

"Effects" The color images of the two-color thermosensitive recording paper of each example were clear for both the low-temperature and high-temperature images, the preservability of the unrecorded portions was good, and no sticking occurred.

Continuation of front page (56) References JP-A-62-234986 (JP, A) JP-A-60-24993 (JP, A) JP-A-53-120541 (JP, A) JP-A-61-280987 (JP, A) JP-A-62-144991 (JP, A) JP-A-57-169393 (JP, A) JP-A-62-284781 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB Name) B41M 5/28-5/34

Claims (3)

(57) [Claims] 1. A leuco-based coloring layer comprising a support and at least a high-temperature coloring layer, an intermediate layer containing a decoloring agent, and a low-temperature coloring layer, wherein the coloring layer contains a leuco dye and a coloring agent. In the two-color heat-sensitive recording material, a phenolic compound having a melting point of 170 ° C. or more is used as a coloring agent of the low-temperature coloring layer, and 1 part by weight of the phenolic compound having a melting point of 170 ° C. or more in the low-temperature coloring layer. A two-color heat-sensitive recording material containing 0.2 to 2 parts by weight of a monophenolic compound or a diphenolic compound having a melting point of 90 to 160 ° C. 2. The two-color heat-sensitive recording material according to claim 1, wherein the coloring agent of the low-temperature coloring layer is 4,4'-cyclohexylidenediphenol. 3. An intermediate layer comprising a layer mainly composed of a decoloring agent and a layer mainly composed of a pigment, which are successively laminated. The layer mainly composed of a pigment contains 50 to 90% by weight of a pigment component. 3. The two-color thermosensitive recording medium according to claim 1, wherein the coating amount is 1 to 5 g / m ² .