JPH0632994B2 - Two-color thermal recording material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a two-color heat-sensitive recording material, and more specifically, a colorless or slightly pale leuco dye and a color developer that reacts with the leuco dye to form a color when heated. The present invention relates to a two-color thermosensitive recording material in which thermosensitive coloring layers containing as a main component are laminated.

[Prior art]

The heat-sensitive recording material is one in which a heat-sensitive color forming layer capable of forming a color-formed 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. As such a conventional heat-sensitive recording material, a lactone ring, a lactam ring,
A colorless or light-colored leuco dye having a spiropyran ring (main coloring agent) and a developer that develops a color by reacting with this leuco dye when heated (coloring auxiliary agent) have a clear color tone and have a fogging effect. It is often used because it has few phenomena.

By the way, the thermosensitive recording material is not only used for copying books, documents, etc., because a colored image can be easily obtained only by heating it, but it is also used in various fields such as electronic calculators, facsimiles, telexes, etc. Depending on the recording application, it is desirable to be able to record the color of that part (display color) by changing it from the color of other parts, in order to display the necessary data and numbers more clearly depending on the purpose of recording. It is natural.

Recently, attempts have been made to obtain multicolor recording by utilizing the difference in heating temperature or the difference in thermal energy, and various multicolor color thermosensitive recording papers have been proposed accordingly. The multicolor color thermosensitive recording paper is generally formed by stacking two kinds of high-temperature and low-temperature color-developing layers, which are colored in different colors with different color-developing heat energies, on a support. It is divided into types. One is to obtain a color tone different from the color tone of the low temperature color layer by mixing with the color tone of the low temperature color layer when the high temperature color layer is colored, and the other is to color the high temperature color layer. In this case, a color erasing agent for erasing the low temperature color developing layer is used to obtain only the color developing color tone of the high temperature color developing layer without color mixture of the color developing color tone of the low temperature color developing layer. As specific examples of these, the former ones include Japanese Patent Publication No. Sho 49-69, Japanese Patent Publication No. Sho 49-4342, Japanese Patent Publication No. Sho 49-27708, and Japanese Patent Laid-Open Publication No. Sho 48-86543.
JP-B-49-65239, and the latter are disclosed in JP-B-50-17865, JP-B-50-17866, JP-B-51-29024, and JP-B-51-87542. JP-A Nos. 50-18048 and 53-47843.

However, in the case of the former multicolor thermosensitive recording paper,
In the case of high-temperature color development, the color tone that can be specifically realized to mix with the color tone of the low-temperature color layer is such that the high-temperature color tone such as red-black, blue-black, etc. is limited to a black type with a strong tone. There is. On the other hand, in the case of the latter multicolor color thermosensitive recording paper, the combination of color tone can be freely selected, but at the time of high temperature color development, higher aliphatic alcohol, polyether, as a decoloring agent for decoloring the low temperature color development layer, Polyethylene glycol derivatives, acetamide as stearamide, stearamide, phthalonitrile as organic nitrogen compounds, guanidine derivatives as amine derivatives, etc. have been proposed. The color tone cannot be completely erased, resulting in color mixing or bleeding of the low temperature coloring layer. Therefore, it is necessary to apply multiple layers of the high temperature color-developing layer, the color erasing agent layer and the low temperature color-developing layer and to make the color erasing agent layer sufficiently thick. However, in such a case, when the high temperature color developing layer is to be colored by a printer having a thermal head, a fax machine, etc., the thermal head needs high energy, and in the case of a recorder, the depth direction of the heat sensitive color developing layer is high when recording at high speed. Since the heat conduction to the ink is low, the lowermost high-temperature color-developing layer does not sufficiently develop color, and only the low-temperature recording color develops.

〔Purpose〕

SUMMARY OF THE INVENTION It is an object of the present invention to provide a leuco-based two-color heat-sensitive recording material which overcomes the above-mentioned problems of the prior art and has good color separation properties and does not cause color mixing in a high-temperature color image.

〔Constitution〕

That is, according to the present invention, a high-temperature color-developing layer, a decoloring agent layer containing a decoloring agent, and a low-temperature color-developing layer are laminated in this order on a support, and the high-temperature color-developing layer and the low-temperature color-developing layer are leuco dyes. Contains a color developer, and the decolorizer layer is N, N'-dithiodiε-
Provided is a two-color heat-sensitive recording material characterized by containing caprolactam.

In the present invention, as the color developer contained in the high temperature color forming layer and the low temperature color forming layer, for example, N, N'-diphenylthiourea, N-p-ethylphenyl-N'-phenylthiourea,
N-p-butylphenyl-N'-phenylthiourea, N,
N'-di-m-chlorophenylthiourea, N, N'-di-p
-Chlorophenylthiourea, N, N'-di-m-trifluoromethylphenylthiourea, N, N'-di-m-methylphenylthiourea, 4,4'-isopropylidenediphenol, 4, 4'-isopropylidene bis (2-chlorophenol), 4,4'-isopropylidene bis (2,6-dibromophenol), 4,4'-isopropylidene bis (2,6-dibrolophenol), 4, 4'-isopropylidene bis (2-methylphenol), 4,4'-isopropylidene bis (2-tert
-Butylphenol), 4,4'-sec-butylidene diphenol, 4,4'-cyclohexylidene bis (2-methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenol Sid, α-naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolak-type phenol resin, 2,
2'-thiobis (4,6-dichlorophenol), catechol, resorcin, hydroquinone, pyroganol, phloroglucin, phloroglysincarboxylic 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-hydroxybenzoic acid-p
-Chlorobenzyl, p-hydroxybenzoic acid-o-chlorobenzyl, p-hydroxybenzoic acid-p-methylbenzyl, p-hydroxybenzoic acid-n-octylbenzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid,
2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenyl sulfone, 4-
Hydroxy-4'-chlorodiphenyl sulfone, bis (4
-Hydroxyphenyl) sulfide and the like.

The leuco dye used in the present invention may be applied alone or in combination of two or more kinds.
What is applied to this type of heat-sensitive material is arbitrarily applied, and for example, leuco compounds of dyes such as triphenylmethane type, fluorane type, phenothiazine type, auramine type and spiropyran type 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 letolactone), 3,3-bis ( p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexyl Amino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benz Fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl-7
-Anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino}
-6-diethylaminofluorane, 2- {3,6-bis (diethylamino) -9 (o-chloroanilino) xanthylbenzoate lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane , 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 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, zen Zoyl leuco methylene blue, 6'-chloro-8'-methoxy-benzoindolino pyrirospiran, 6'-bromo 3'-methoxy-benzoindolino pyrirospiran, 3- (2'-hydroxy-4'-dimethylamino (Phenyl)
-3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl)
-3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl)
-3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3
-(2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-proridino-7-trifluoromethylanilino Fluorane, 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) fluorane, 3-diethylamino-7- (o-methoxycarbonylfluor) (Enylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2- Rollo-3-(N-Mechirutoruijino) -7- (p-n-
Butylanilino) fluorane, 3- (N-benzyl-N-cyclohexylamino) -5,6-
Benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino-4 ′,
5'-benzofluorane and the like.

In the present invention, specific examples of particularly preferred leuco dyes to be contained in the high temperature color forming layer include, for example, 3-diethylamino-7-chlorofluorane and 3-diethylamino-6.
-Methyl-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylaminobenzo [α] fluorane and the like can be mentioned.

In the present invention, in order to bond and support the leuco dye and the color developer on a support, various conventional binders can be appropriately used, and examples thereof include polyvinyl alcohol, starch and its derivatives, methoxycellulose and hydroxy. Cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, and stellene / Maleic anhydride copolymer alkali salt,
Isobutylene / maleic anhydride copolymer Alkaline salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic acid ester A latex such as a vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, or styrene / butadiene / acrylic copolymer can be used.

Further, in the present invention, together with the leuco dye and the color developer, if necessary, further auxiliary components commonly used in this type of heat-sensitive recording material, for example, a filler, a surfactant, a heat-fusible substance ( Alternatively, a lubricant) or the like can be used in combination. In this case, as the filler, for example, calcium carbonate, silica,
Zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, other inorganic fine powder such as surface-treated calcium and silica, urea-formalin resin, styrene / methacrylic acid copolymer, Examples thereof include organic fine powders such as polystyrene resin. Examples of the heat-fusible substance include higher fatty acids or their esters, amides or metal salts, various waxes, aromatic carboxylic acids and amines. Condensates, benzoic acid phenyl esters, higher linear glycols, 3,4-epoxy-dialkyl hexahydrophthalates, higher ketones, and other heat-fusible organic compounds having a melting point of about 50 to 200 ° C Can be mentioned.

[Effect]

The two-color heat-sensitive recording material of the present invention has the above-mentioned constitution, and the decolorizing agent used in the present invention has a high decoloring effect even when black low temperature coloring is used, and therefore, for example, low temperature coloring is black and high temperature coloring is red. The color composition can be vividly developed.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples. The parts and% shown below are based on weight.

Example 1 Dispersions A to D were prepared by pulverizing and dispersing the following components in a ball mill for 24 hours.

[Dispersion-A]

3- (N-ethyl-N-amylamino) -6-methyl-7-anilinofluorane (black) 20 parts 10% hydroxyethyl cellulose aqueous solution 20〃 water 60〃 [dispersion liquid-B] benzyl p-hydroxybenzoate 15 Part Calcium carbonate 15〃 Polyvinyl alcohol (10% aqueous solution) 30〃 Water 40〃 [Dispersion-C] 3-Diethylamino-7-chlorofluorane (red) 20
Part 10% Hydroxyethyl cellulose aqueous solution 20〃 Water 60〃 [Dispersion-D] Bisphenol A 12 parts Ethylene distearoamide 6〃 Calcium carbonate 9〃 10% Polyvinyl alcohol aqueous solution 30〃 Water 43〃 Dispersion prepared as above Liquid A 10 parts, Dispersion B 60 parts,
30 parts of water was taken and mixed and stirred to obtain a low temperature thermosensitive color forming solution. On the other hand, 10 parts of dispersion C, 60 parts of dispersion D, 30 parts of water
Each part was taken, mixed and stirred to obtain a thermosensitive color forming layer forming liquid for high temperature color forming.

Further, a decolorant layer forming liquid for forming a decolorant layer was prepared in the following ratio.

[Decolorant layer forming liquid]

N, N-dithiodi ε-caprolactam 20 parts 10% polyvinyl alcohol aqueous solution 20 parts water 60 〃 Each liquid prepared as above is applied to a high-quality thermosensitive coloring layer for high temperature on a commercial high-quality paper with a basis weight of about 52 g / m ^2. Forming liquid (usual amount of dry cloth, 6
g / m ² ), decolorizer layer forming liquid (dry coating amount 2.5 g / m ² ), low temperature heat-sensitive color forming layer forming liquid (dry coating amount 3.5 g / m ² ), then dried. A two-color heat-sensitive recording material of the present invention was obtained by carrying out a calendering treatment at a rate of 500 to 1500 sec.

Comparative Example N, N-dithiodiε used as a decolorizing agent in Example 1
A two-color heat-sensitive recording material for comparison was obtained in the same manner as in Example 1 except that distearylamine was used instead of caprolactam.

The two-color color heat-sensitive recording material obtained as described above was measured with a printing tester for Fasimil having a thin film head at 0.6w.
A color development test was performed with / dot and a platen pressure of 3 kg / A-4 width.
The results are shown in Table 1.

As can be seen from Table-1, the two-color heat-sensitive recording material of the present invention is capable of obtaining black color at low-temperature color development and red color development at high-temperature color development, and further capable of obtaining a clear image without color mixture. It is a material.

Claims (1)

[Claims] 1. A high-temperature color-developing layer, a decoloring agent layer containing a decoloring agent, and a low-temperature color-developing layer which are successively laminated on a support, wherein N, N'-dithiodiε-caprolactam is used as the decoloring agent. A two-color thermal recording material characterized by being used.