JPS62294588A - Two-color thermal recording material - Google Patents

Abstract

PURPOSE:To provide a two-color thermal recording material capable of obtaining a sharp reddish high temp. developed color image, excellent in preservability such as heat resistance and humidity resistance, etc. and reduced in background fogging, by using a compound represented by a specific formula as the coupler of a high temp. color forming layer and further a waxy substance having specific m.p. in said layer. CONSTITUTION:In a two-color thermal recording material wherein a high temp. color forming layer, a color erasing layer and a low temp. color forming layer are successively laminated to a support in this order, a compound represented by formula (I) (wherein Z is -S-, A or B and R1, R2, R3 and R4 are H or a 1-4C alkyl group) is used as the coupler of the high temp. color forming layer and a waxy substance with m.p. of 70-200 deg.C is used. As the waxy substance, for example, ones having m.p. of about 70-200 deg.C such as higher fatty acid, ester thereof and other heat-meltable org. compound etc. are designated. In this case, when m.p. of the waxy substance is 70 deg.C or less, background fogging is generated or the effect of a color erasing agent becomes easy to generate and a sharp image is not obtained and, when said m.p. is 200 deg.C or more, the color formation of the high temp. color forming layer is obstructed and a sharp high temp. developed color image is not obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Technical Field] The present invention relates to a two-color heat-sensitive recording material, and more specifically, a leuco dye that is usually colorless or slightly pale in color and a leuco dye that reacts with the leuco dye when heated. The present invention relates to a two-color heat-sensitive recording material formed by laminating heat-sensitive color-forming layers containing as a main component a color developer that develops color.

[Prior art]

A thermosensitive recording material is a material in which a thermosensitive coloring layer capable of forming a colored image by heating is provided on a support such as paper, and a thermal printer equipped with a thermal head is widely used for heating.

These conventional heat-sensitive recording materials include a colorless or light-colored leuco dye (color-forming main agent) having a lactone ring, lactam ring, spiropyran ring, etc. in the heat-sensitive coloring layer, and a color developer that develops color by reacting with this leuco dye when heated. Agent (coloring aid)
Those containing these are widely used because they have clear color tones and less fogging.

By the way, heat-sensitive recording materials can easily produce colored images just by heating them, so they are not only used for copying books, documents, etc., but are also used in various fields such as computer, facsimile, telex, and other fields for recording various types of information and measuring equipment. However, depending on the purpose of recording, in order to display particularly necessary data and numbers more clearly, the coloring of that part (
It goes without saying that it is desirable to be able to record with the display color (displayed color) different from the developed color of other parts.

Recently, attempts have been made to obtain multicolor recording by utilizing differences in heating temperature or thermal energy, and various multicolor thermosensitive recording papers have been proposed accordingly. Multi-color thermosensitive recording paper is generally formed by stacking two types of high-temperature and low-temperature coloring layers that develop different tones with different coloring heat energies on a support, and can be broadly classified into the following two types: Divided into types. One is to mix the color with the color tone of the low temperature coloring layer when coloring the high temperature coloring layer to obtain a color tone different from the coloring tone of the low temperature coloring layer, and the other is to color the high temperature coloring layer. In this case, by using a decoloring agent that decolorizes the low-temperature color-forming layer, only the color tone of the high-temperature color-forming layer is obtained without color mixture of the color tone of the low-temperature color-forming layer. As specific examples of these, the former is disclosed in Japanese Patent Publication No. 49-69, Japanese Patent Publication No. 4342-1972, Publication No. 27708-1977,
JP-A-48-86543, JP-A-49-6523
9, etc., and the latter was published in the Special Publication No. 1973.
-17865 Publication, Special Publication No. 50-17866,
Special Publication No. 51-29024, Special Publication No. 5]-8754
Publication No. 2, Japanese Unexamined Patent Application Publication No. 18048/1983, Japanese Patent Publication No. 1983
-36519, etc., respectively.

However, in the case of the former multicolor thermosensitive recording paper,
When coloring at a high temperature, the color tones that can be concretely achieved in order to mix the color with the color tone of the low temperature coloring layer are limited to black threads where the high temperature coloring tone is strong, such as red-black, blue-black, etc. There is. On the other hand, in the case of the latter multicolor thermosensitive recording paper, the combination of color tones can be freely selected, but when coloring at high temperatures, high aliphatic alcohols, polyethers, polyethylene glycol derivatives,
Acetamide, stearamide, phthalonitrile as nitrogen-containing organic compounds, guanidine derivatives, morpholine derivatives, etc. as amine derivatives are used. but,
Such multicolor recording materials have a problem in that during image formation, the density of the high-temperature colored image decreases due to the influence of the decoloring agent, making it impossible to obtain a clear high-temperature colored image.

〔the purpose〕

An object of the present invention is to provide a two-color thermosensitive recording material which can obtain a bright red high-temperature coloring layer, has excellent storage stability such as heat resistance and moisture resistance, and has little background fogging.

〔composition〕

According to the present invention, in a two-color thermosensitive recording material in which a high-temperature coloring layer, a decoloring layer, and a low-temperature coloring layer are laminated in that order on a support,
A compound represented by the following general formula (A) is used as a color developer for the high-temperature coloring layer, and further has a melting point of 70°C to 200°C.
There is provided a two-color heat-sensitive recording material characterized in that it uses a wax-like substance.

and Ro, R2, R1 and R4 represent H or an alkyl group having 1 to 4 carbon atoms.6) Conventionally, as a color developer for a high temperature coloring layer of a two-color thermosensitive recording material, phenol derivatives, p-benzyl Benzoic acid ester derivatives, thiourea derivatives, etc. have been proposed, but those containing these color developers in the high-temperature coloring layer may cause skin problems when stored for long periods of time in high-temperature or high-humidity environments. There are problems with storage, such as fogging and discoloration when fingerprints etc. are attached.
Furthermore, when a two-color image is formed, the decoloring agent also acts on the high-temperature coloring layer, making it impossible to obtain a clear high-temperature coloring image.

Regarding this point, the present inventors previously found that when the compound represented by the general formula (A) is used as a color developer for a high-temperature coloring layer, no coloring occurs due to background fogging or fingerprints during long-term storage. However, it has been found that even in this case, there is a problem in that during two-color image formation, the decoloring agent also acts on the high-temperature color forming layer, making it impossible to obtain a sufficiently clear image.

In order to improve this point, the present inventors conducted extensive research and found that when the high-temperature coloring layer contains a compound represented by the general formula (A) and a wax-like substance with a melting point of 70°C to 200°C. found that these shortcomings could be overcome,
This has led to the completion of the present invention.

Specific examples of the compound represented by the general formula (A) used in the present invention include the following.

The wax-like substances used in the present invention include, for example, higher fatty acids or their esters, amides, or metal salts, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear chain 70 such as glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermofusible organic compounds.
Examples include those having a melting point of about ~200°C.

In this case, if the melting point of the wax-like substance is below 70°C, background fogging will occur, and it will be easily affected by the decoloring agent, making it impossible to obtain a clear image, and if it is above 200°C, the high-temperature coloring layer will Color development is inhibited and clear high-temperature color images cannot be obtained.

Further, in the present invention, in the high-temperature coloring layer, the color developer represented by the general formula (A) is 4 parts by weight or more per 1 part by weight of the leuco dye used in the high-temperature coloring layer, and the color developer and It is preferable that the total amount of waxy substances is 6 parts by weight or more.

If it is less than this, the influence of the decoloring effect of the decoloring agent becomes significant when forming a high-temperature color image, and a clear high-temperature color image cannot be obtained.

Although the reason why the present invention achieves the above-mentioned effects is not clear, the compound represented by the general formula (A) is used as a color developer as a component of the high-temperature coloring layer, and the compound having a melting point of 7.
Because we used a waxy substance with a temperature of 0°C to 200°C,
Color development due to background fog or oil marks during long-term storage is suppressed, and the wax-like substance has a quick thermal response and is difficult to become supercooled, so as a result, the thermal responsiveness of the high-temperature coloring layer also decreases. This is thought to make it difficult for the decolorizing agent and the high-temperature coloring layer to mix because the solidification rate during formation of a high-temperature coloring image becomes faster.

In the present invention, the color developer contained in the low-temperature coloring layer includes, for example, N,NL-diphenylthiourea,
N-P-ethylphenyl-N'-phenylthiourea, N
-P-butylphenyl-N'-phenylthiourea, N,
N'-di1rchlorophenylthiourea, N,N'-di-P-chlorophenylthiourea, N,N'-di-m-trifluoromethylphenylthiourea, N,N'-di-m-
Methylphenylthiourea, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2
-chlorophenol), 4,4'-isopropylidene bis(2,6-dibromophenol), 4,4'-isopropylidene bis(2,6-dichlorophenol), 4
．． 4'-isopropylidene bis(2-methylphenol), 4,4'-isopropylidene bis(2-ter
t-butylphenol), 4,4'-5ec-butylidenediphenol, 4,4'-cyclohexylidenebis(2-methylphenol), 4-tertnibutylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol .

β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolak type phenolic resin, 2,2'
-thiobis(4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyroganol, phloroglucin, phloroglycin carboxylic acid, 4-tert
-octylcatechol, 2,2'-methylenebis(4-
chlorophenol), 2,2'-methylenebis(4-
methyl-6-tert-butylphenol), 2,2'
-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate,
p-hydroxybenzoate-P-chlorobenzyl, p-hydroxybenzoate-0-chlorobenzyl, p-hydroxybenzoate-P-methylbenzyl, p-hydroxybenzoate-n-octylbenzoic acid, zinc salicylate, 1- Hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoic acid, 4-hydroxydiphenylsulfone, 4-hydroxy-41-
Chlorodiphenylsulfone, bis(4-hydroxyphenyl)sulfide, etc. are used.

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. . Specific examples of such leuco dyes include those shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(P- dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(P-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6- Chlorfluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoromethylphenyl)amino)-6-dinithylaminofluorane, 2-(3,
6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(ll11-trichloromethylanilino)fluoran, 3-diethylamino-7-(o-chloroanilino) ) fluoran, 3-dibutylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl=7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3 (N,N-diethylamino )-5-methyl-7-
(N.

N-dibenzylamino)fluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylosubiran, 6'-bromo-3'-methoxy-benzoindolino-pyrylosubiran, 3-(2'- Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-51-chlorophenyl)phthalide, 3-(2'-hydroxy-41-dimethylaminophenyl)-3-(2'-methoxy-5' -nitrophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethyl) aminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N- benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluorane, 3- (N-ethyl-P-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(O-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α- phenylethylamino) fluorane.

3-diethylamino-7-piperidinofluorane.

2-chloro-3-(N-methyltoluidino)-7-(ρ
-n-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

In the present invention, specific examples of particularly preferable leuco dyes to be included in the high-temperature coloring layer include:

3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-
Examples include cyclohexylamino-6-chlorofluorane, 3-diethylaminobenzo[α]fluorane, and the like.

As the color erasing agent used in the present invention, various conventionally known color erasing agents such as those shown in the explanation of the prior art can be used. Formula (1), (II), (II
Compounds represented by I), (IV) and (V), compounds having three or more amide groups in the molecule, or two or more amide groups and one or more tertiary amino groups, N ,
Preference is given to using N'-dithiocaprolactam and the like.

General formula (I) General formula (II) General formula (III) General formula (rV) General formula (V) In the above general formulas (I), (n) and (III), R and R2 have a substituent. is optionally alkyl, cycloalkyl, aryl or aralkyl, and X is carbonyl or sulfonyl. The alkyl represented by R1 and R2 is usually a straight chain or branched chain having 1 to 18 carbon atoms, the cycloalkyl is cyclohexyl, and the aryl is phenyl, tolyl, 1,000, Examples of aralkyl include silyl and the like, and examples of aralkyl include benzyl and phenethyl. These substituents may further have other substituents, such as eg alkyl, aryl.

In addition to halogen, alkoxy, aryloxy, acyl, acyloxy, alkoxycarbonyl, carbamoyl, acylamino, etc. can be mentioned. In addition, the piperazine ring in general formulas (1) to (m) also includes alkyl,
One or more substituents such as aryl, halogen, alkoxy, aryloxy, acyl, acyloxy, alkoxycarbonyl, carbamoyl, and acylamino may be bonded.

Specific examples of the compound represented by the general formula (1) include the following.

N-methyl-N'-phenylacetylpiperazine, N-
Propyl-N'-phenylacetylpiperazine, N-propyl-N'-benzoylpiperazine, N-butyl-N'-benzoylpiperazine, N-cyclohexyl-N'-benzoylpiperazine, N-hexyl-N'-benzoyl piperazine, N-lauryl-N'-benzoylpiperazine, N-stearyl-
N'-benzoylpiperazine, N-phenyl-N'-benzoylpiperazine, N-benzyl-N'-benzoylpiperazine, N-phenyl-N'-cyclohexyloylpiperazine, N-phenyl-N'-acetylpiperazine, N -phenyl-N'-lauroylpiperazine, etc.

Specific examples of the compound represented by the general formula (II) include the following.

N,N'-bis(benzenesulfonyl)piperazine,
N,N'-bis(p-methylbenzenesulfonyl)piperazine, N,N'-bis(P-isopropylbenzenesulfonyl)piperazine, N,N'-bis(p-chlorobenzenesulfonyl)piperazine, N,N'-bis (0-chlorobenzenesulfonyl)piperazine.

N,N'-bis(m-chlorobenzenesulfonyl)piperazine.

N,N'-bis(p-bromobenzenesulfonyl)
Piperazine, N,N'-bis(butylsulfonyl)piperazine, N
, N'-bis(octylsulfonyl)piperazine, N
, N'-bis(laurylsulfonyl)piperazine, N
, N'-bis(stearylsulfonylpiperazine), N,N'-bis(cyclohexylsulfonyl)piperazine, N,N'-bis(p-laurylbenzenesulfonyl)
piperazine, N,N'-bis(cyclohexylsulfonyl)piperazine, and the like.

Specific examples of the compound represented by the general formula (m) include the following.

N,N'-bis(butyroyl)piperazine, N,N'
-Bis(hexyloyl)piperazine, NHN' -
Bis(n-ofthyroyl)piperazine, N, lit'
-bis(tertiary-oftyroyl)piperazine, N,N'-bis(lauriloyl)piperazine.

N,N'-bis(steacoil)piperazine, N,N
' -bis(pivaloyl)piperazine.

N,N'-bis(cyclohexyloyl)piperazine,
N,N'-bis(P-methylcyclohexyloyl)piperazine, N,N'-bis(ρ-methylphenylacetyl)piperazine, N,N'-bis(phenylacetyl)piperazine.

N,N'-bis(phenylpropionyl)piperazine, N,N'-bis(benzoyl)piperazinone.

N, N'-bis(phenoxyacetyl)piperazine, N
, N'-bis(P-chlorobenzoyl)piperazine,
N,N'-bis(2-phenoxypropionyl)piperazine and the like.

In the general formula (■), R1, R2, R3 and R4 represent substituted or unsubstituted alkyl, cycloalkyl, aryl or aralkyl, and R1 and R2 or R3 and R4 are
The ends can also be joined together to form a ring. The alkyl usually includes a straight chain or branched chain having 4 to 18 carbon atoms, the cycloalkyl includes cyclohexyl, the aryl includes phenyl, tolyl, xylyl, etc. Examples of alkyl include benzyl and phenethyl. These substituents can further have other substituents, and examples of such substituents include alkyl, aryl, alkoxy, acyl, halogen, acylamino such as benzoylamino and acetylamino, alkoxy Carbonyl, carbamoyl, aryloxy, aralkyloxy and the like can be mentioned. A is a fatty acid group or an aromatic group; in the case of an aliphatic group, it is usually a substituted or unsubstituted alkylene having 1 to 8 carbon atoms; in the case of an aromatic group,
Substituted or unsubstituted arylene such as tolylene, tolylene, xylylene, etc., and in this case, the substituent includes the above-mentioned halogen, acylamino, alkoxycarbonyl, carbamoyl, aryloxy, aralkyloxy, etc. .

Specific examples of the disubstituted amide compounds of aliphatic and aromatic dihydric carboxylic acids include the following.

N,N,N'N'-Tetrabutylsuccinic acid diamide.

N,N,N'N'-Tetraoctylsuccinic acid diamide, N,N,N'N'-tetralaurylsuccinic acid diamide.

N,N,N'N'-tetrastearylsuccinic acid diamide, N,N,N'N'-tetraphenyladipic acid diamide, N,N,N'N'-tetra-P-butylphenyladipic acid diamide, N , N, N'N' -tetrabutyl adipate diamide, N, N, N'N' -tetraoctyl adipate diamide, N, N, N'N' -tetralauryl adipate diamide, N, N, N'N'-tetrastearyladipate diamide, N,N'-dicyclohexyl-N,N'-dimethylsuccinic acid diamide.

N,N'-isophthaloyl bispyrrolidine, N,N'
-phthaloylbis-diethylamine, N,N'-terephthaloylbis-diethylamine, N,N'-isophthaloylbis-diethylamine, N,N'-phthaloylbis-diethylamine, N,N'-terephthaloylbis-diethylamine Propylamine, N,N'-isophthaloylbis-dipropylamine, N,N'-terephthaloylbis-dibutylamine, N,N'-isophthaloylbis-
Dibutylamine, N,N'-terephthaloylbis-cyclohexyl-methylamine, N,N'-isophthaloylbiscyclohexyl-methylamine, N,N'-terephthaloylbis-dicyclohexyl-
Amine, N,N'-isophthaloylbis-dicyclohexyl-
Amin et al.

In the general formula (V), R1 and R2 represent alkyl, cycloalkyl, aryl, or aralkyl which may have a substituent. The alkyl usually includes a straight chain or branched chain having 1 to 18 carbon atoms, the cycloalkyl includes cyclohexyl, the aryl includes phenyl, tolyl, xylyl, etc. Examples of alkyl include benzyl and phenethyl.

These substituents can further have other substituents, such as alkyl, aryl, halogen, alkoxy, aryloxy, aralkyloxy, acyl, acyloxy, alkoxycarbonyl, carbamoyl, Examples include substituents such as acylamino. Yl and Y2 are linear or branched carbon atoms of 1 to 18
is an alkylene group.

Specific examples of such compounds include the following.

N,N'-bis(benzoylaminoethyl)piperazine, N,N'-bis(benzoylaminopropyl)piperazine, N,N'-bis(benzoylaminobutyl)piperazine.

N,N'-bis(cyclohexylaminopropyl)piperazine, N,N'-bis(hexylaminopropyl)piperazine, N-benzoylaminopropyl-N'-cyclohexylaminoethylpiperazine, N-benzoylamino Propyl-N'-benzoylaminobutylpiperazine.

N (p-chlorobenzoylaminoamino) -N'-
Benzoylaminopropylpiperazine, N-cyclohexyloylaminopropyl-N'-cyclohexyloylaminobutylpiperazine, and the like.

Further, specific examples of the compound having three or more amino groups, two or more amide groups, and one or more tertiary amino groups in the molecule include the following.

N,N',N'-tribenzoyl-diethylenetriamine, N,N'-N'-tribenzoyl-dipropylenetriamine.

N, N', N', N-tetrabenzoyl-triethylenetetramine, 1,7-dibenzoyl-4-methyl-diethylenetriamine, 1,9-dibenzoyl-5-methyl-dipropylenetriamine.

1.7-di-α-naphthoyl-4-methyl-diethyltriamine, 1.7-di-α-naphthoyl-4-cyclohexyl-diethylenetriamine, N, N', N'-tripiparoyl-diethylenetriamine, N, N', N' , N-tetraacetyl-triethylenetetramine.

N, N', N', N-tetracyclohexyloyl-
Triethylenetetramine etc.

In the present invention, in order to bind and support the leuco dye, color developer, and decolorizer on the support, various conventional binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxycellulose,
Cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid ester/methacrylic acid ternary copolymer, styrene Water-soluble polymers such as / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer Latexes such as polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

In addition, in the present invention, in addition to the leuco dye and color developer, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers and surfactants, may be used in combination, if necessary. . In this case, the filler is, for example, calcium carbonate.

Silica, zinc oxide, titanium oxide, aluminum hydroxide,
In addition to inorganic fine powders such as zinc hydroxide, barium sulfate, clay, talc, and surface-treated calcium and silica, urea-polymarine resin, styrene/methacrylic acid copolymer,
Examples include organic fine powder such as polystyrene resin. Further, if necessary, a thermofusible substance commonly used in this type of field can be used for the low-temperature coloring layer. In this case, examples of the thermofusible substance include higher fatty acids or their esters, amides, In addition to metal salts, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermoplastics. Examples include melting organic compounds having a melting point of about 50 to 200°C.

Further, in the present invention, a protective layer may be provided on the low-temperature coloring layer in order to improve matching properties (head dregs, sticking, etc.) with the thermal head.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 Each of the following ingredients was prepared using a sand mill to give an average particle size of 2 to 2.
The powder was pulverized and dispersed to a particle size of 3 μm to prepare a dispersion liquid A-I).

[Dispersion liquid-A]

3-(N-ethyl-N-amylamino)-6-methyl-
7-anirithufluoran (black) 20 parts 10% hydroxyethyl cellulose aqueous solution 2077 water
60 [Dispersion-B] 3-diethylamino-7-chlorofluoran (red) 2
0 parts 10% hydroxyethyl cellulose aqueous solution 20 parts water
60 [Dispersion-B] 3.3-Dichlorophenylthiourea 10 parts Calcium carbonate 10 parts Polyvinyl alcohol (10% aqueous solution) 20 Water
10 parts of dispersion A prepared in the above manner, 70 parts of dispersion C, and 20 parts of water were each taken and mixed and stirred to obtain a thermosensitive color forming liquid for low temperature use.

[Dispersion liquid-B]

4.4-Cyclohexylidene bisphenol 10 parts Zinc stearate 4 tr Calcium carbonate 101! 10% hydroxyethyl cellulose 15 Water
61//
[Dispersion-B] A dispersion in which N-octadecylcarbamoyl-P-methoxycarbonylbenzene was used instead of zinc stearate.

[Dispersion-F]

4.4'-Thiobis(2-t-butyl-5-methyl)phenol 10 parts Zinc stearate 4 N Calcium carbonate 10 parts 10% hydroxyethyl cellulose 15 Water
61 [Dispersion-B] 4.4'-Cyclohexylidene bisphenol 10 parts Calcium carbonate 10 1o%
Hydroxyethyl cellulose 15 water
65〃
[Dispersion-B] 4.4'-thiobis(2-t-butyl-5-methylphenol) 10 parts Calcium carbonate 10810%
Hydroxyethyl cellulose 15 water
55u [
Dispersion method] Bisphenol A 10 parts Calcium carbonate 10 1 hydroxyethyl cellulose 15 Water
65 [Dispersion-J] Bisphenol A 10 parts Zinc stearate 4 Calcium carbonate 1011 10% hydroxyethyl cellulose 15n Water
61 Furthermore, a decolorizing agent layer forming liquid for forming a decolorizing agent layer was prepared at the following ratio.

[Decolorizer layer forming liquid]

4.4-dithiodimorpholine 20 parts 1
0% polyvinyl alcohol aqueous solution 'lQn water
6011 Next, dispersion liquid 85
1 part, 60 parts of dispersion D, and 10 parts of water were mixed and stirred to prepare a high-temperature coloring layer forming solution, and the dry adhesion amount of leuco dye was 0.5.
g/rd and dried to form a high temperature coloring layer. Next, apply the decolorizing agent forming liquid on top of it until the dry adhesion amount is 3.
．． 5g/n (coat and dry to form a color erasing layer, and further apply the low temperature color forming layer forming solution to a layer with a leuco dye adhesion amount of 0.5g/n).
It was coated and dried to form a low-temperature coloring layer at a rate of 4 g/rr (2-color heat-sensitive recording material P1).

[Example 2] A two-color thermosensitive recording material P2 was obtained in the same manner as in Example 1, except that dispersion E was used instead of the dispersion in the high-temperature coloring layer forming liquid.

[Example 3] A two-color thermosensitive recording material P3 was obtained in the same manner as in Example 1, except that dispersion F was used instead of dispersion in the high-temperature coloring layer forming liquid.

[Comparative Example 1] A two-color thermosensitive recording material C1 was obtained in the same manner as in Example 1, except that dispersion G was used instead of the dispersion in the high-temperature coloring layer forming liquid.

[Comparative Example 2] A two-color thermosensitive recording material C2 was obtained in the same manner as in Example 1, except that dispersion H was used instead of the dispersion in the high-temperature coloring layer forming liquid.

[Comparative Example 3] Two-color thermosensitive recording material C3 was obtained in the same manner as in Example 1, except that dispersion liquid (2) was used instead of dispersion liquid in the high-temperature coloring layer forming liquid.

(Comparative Example 4) A two-color thermosensitive recording material C4 was obtained in the same manner as in Example 1, except that Dispersion J was used in place of the dispersion liquid in the high-temperature color forming layer forming liquid.

[Comparative Example 5] In Example 1, Dispersion 85 was used as the high temperature coloring layer forming liquid.
A two-color thermosensitive recording material C5 was obtained in the same manner except that a mixture of 15 parts of Dispersion D and 55 parts of water was mixed and stirred.

Regarding the samples obtained in Examples 1 to 3 and Comparative Examples 1 to 5, the concentration and the conditions of 40 ° C. and 90% RH were
The background density and high temperature color density after storage for a period of time were tested. The test results are shown in Table 1 below.

The test machine was an 8 dot/l manufactured by Matsushita Electronic Components Co., Ltd.
It has a thermal head of l11, and the heating element resistance is about 400.
Ω/dot, and the color development test was performed at a main scanning recording speed of 2
The test was carried out under the following conditions: 0m5ec/1ine, sub-scanning 1.7Q/mcm, platen suppression 3.0kg/aJ, and head input 0.6W/dot.

In addition, a Macbeth densitometer (RD-514, filter lt-106 black coloring, t58 red coloring) was used for density measurement.

Table 1 [Effects] As can be seen from Table 1, the two-color thermosensitive recording material of the present invention is capable of obtaining high-density and clear high-temperature colored images, and has excellent storage stability over time. It is a heat-sensitive recording material.

Claims (3)

[Claims] (1) In a two-color thermosensitive recording material in which a high-temperature coloring layer, a decoloring layer, and a low-temperature coloring layer are laminated in that order on a support, a compound represented by the following general formula is used as a color developer in the high-temperature coloring layer, A two-color heat-sensitive recording material further comprising a wax-like substance having a melting point of 70°C to 200°C. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, Z represents -S-, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_1, R_2, R_3 and R_4 represents H or an alkyl group having 1 to 4 carbon atoms.) (2) The two-color heat-sensitive recording material according to claim (1), wherein the waxy substance is a fatty acid, a fatty acid metal salt, or a fatty acid amide. (3) Claim (1) in which the color developer is contained in 4 parts by weight or more with respect to 1 part by weight of the leuco dye in the high-temperature coloring layer, and the total amount of the color developer and wax-like substance is 6 parts by weight or more.
Two-color heat-sensitive recording material described in Section 1.