JPH0777822B2 - Multicolor thermal recording material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a multicolor thermosensitive recording material, and more particularly to a multicolor thermosensitive recording material obtained by laminating a plurality of thermosensitive coloring layers having different color tones.

[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.
Japanese Patent Publication No. Sho 49-65239 and the like, and the latter ones are disclosed in Japanese Patent Publication No. 50-17865 and Japanese Patent Publication No. 50-17866.
JP-B No. 51-29024, JP-B No. 51-87542, JP-A No. 50-18048, and JP-A No. 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 coloring colors can be freely selected, but it is necessary to provide an erasing layer containing an erasing agent for erasing the low temperature coloring layer during high temperature coloring. There is. It has been proposed to use an aliphatic amine, an aromatic amine, a polyether or the like as such a decoloring agent. However, these decolorizers have the drawbacks that the storage stability is extremely poor, the decoloring action re-advances with the passage of time, humidity, and temperature, resulting in deterioration of the color image of the low-temperature color-developing layer and further complete decolorization. It was

〔Purpose〕

[It is an object of the present invention to provide a multicolor thermosensitive recording material which overcomes the above-mentioned problems of the prior art and is excellent in image stability of a low temperature color forming layer.

〔Constitution〕

According to the present invention, two or more thermosensitive coloring layers having different coloring energies and different coloring tones are sequentially laminated on the support so that the one having smaller coloring energy is the upper layer and A multicolor heat-sensitive recording material having at least one decoloring layer between color forming layers, containing a compound having a structure represented by the following general formula (I) and having a melting point in the range of 140 to 250 ° C. A featured multicolor thermal recording material is provided.

(In the formula, R ₁ and R ₂ are an alkyl group, a cycloalkyl group,
Represents an aryl group or an aralkyl group. The compound of the general formula (I) used in the present invention is usually
Although it is a white powder, it is hardly soluble in water and can be used as a decoloring agent, but it can also be used in combination with other conventional decoloring agents. The amount used can be appropriately selected, but 1.0 g / m ² ~
5.0 g / m ² is suitable.

The compound represented by the general formula (I) used in the present invention needs to have a melting point in the range of 140 to 250 ° C. In this case, when the melting point is lower than 140 ° C., the decoloring action re-advances due to temperature and humidity, and the image density of the low temperature color developing layer becomes low. On the other hand, when the temperature is higher than 250 ° C., the color is not sufficiently erased and a color mixture is exhibited. Therefore, when the melting point is in the above range, a multicolor thermosensitive recording material having excellent image stability and color separation of the low temperature color developing layer can be obtained.

Specific examples of the compound represented by the general formula (I) are as follows.

Bis (N-benzyl-N-cyclohexyl) terephthalamide, bis (N-butyl-N-phenyl) terephthalamide, bis (N-methyl-N-benzyl) terephthalamide.

The leuco dyes used in the present invention may be used alone or as a mixture of two or more, and as such leuco dyes,
What has been applied to this type of heat-sensitive material is arbitrarily applied, for example, triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, indolinophthalide-based dye leuco compounds 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-dimethyl) Aminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofurfuride Oran, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-hensfluorane, 3-diethylamino -6-Methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl- -Anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N-3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6- Bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoic acid 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, benzoyl leuco methylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrolispirane, 6'-bromo-3'-methoxy-benzoindolino-pyrrolispirane, 3- (2'-hydroxy) -4'-Dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl)
Phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl)
Phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -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-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) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α -Phenylethylamino) fluorane, 3-diethylamino-7-piperidi Fluoran, 2-chloro-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, various electron-accepting substances are applied as the color developing agent that reacts with the leuco dye when heated to develop it, and a phenolic substance, an organic or organic acidic substance or a metal salt thereof, Aromatic amide compound,
Examples thereof include aromatic urea compounds, and specific examples thereof will be shown below.

Clay, activated clay, activated silica, boric acid, zinc oxide, zinc chloride, aluminum chloride, 4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis- (o
-Cresol), 4,4'-isopropylidene bis (o-t
ert-butylphenol), 4,4'-isopropylidene-
Bis (o-chlorophenol), 4,4'-cyclohexylidene bisphenol, 4,4'-bisphenol sulfone, 4-hydroxy-4'-chloro-diphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, Isopropyl p-hydroxybenzoate, p-
Benzyl hydroxybenzoate, p-chlorobenzyl p-hydroxybenzoate, anilide salicylate, salicylic acid- (o-chloroanilide), salicylic acid- (n-trifluoromethylanilide), dimethyl 4-hydroxyphthalate, 2-hydroxy-3. -Naphthoic acid, benzyl 2-hydroxy-3-naphthoate, 2-hydroxy-3-naphthoic acid anilide, zinc 2-hydroxy-3-naphthoate, zinc chloride / antipyrine complex, methylenebis- (oxyethylenethio) diphenol, 4-hydroxyacetophenone, novolac type phenol resin, novolac type phenylphenol resin, diphenylthiourea, di (m-chlorophenyl) thiourea, di (m-trifluoromethylphenyl) thiourea type and the like.

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, styrene / Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, polyvinyl acetate,
Polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutal methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene / acrylic copolymer, etc. Latex can be used.

Further, in the present invention, together with the leuco dye and the color developer, if necessary, further auxiliary additives 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, inorganic fine powder such as surface-treated calcium or silica, etc. , Urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, and other organic fine powders,
Examples of heat-fusible substances include higher fatty acids or their esters, amides or metal salts, as well as various waxes,
50-200 ° C for condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, 3,4-epoxy-dialkyl hexahydrophthalates, higher ketones, other heat-fusible organic compounds, etc. Those having a melting point of about

For example, to obtain a two-color thermosensitive recording material according to the present invention,
It can be obtained by coating and drying a liquid in which a color-forming dye, a color developer, a decoloring agent, a binder and the like are dispersed or dissolved on a support such as paper, synthetic paper and a plastic film, and repeating this. In the case of further laminating on the coated layer, it is necessary to pay sufficient attention to the solubility and the peelability of the layer so that the lower layer does not mix with the upper layer. Further, the upper layer may be applied after the coating and drying and the calender treatment. Dye deposition amount of the high-temperature coloring ^{layer, 0.3g / m 2 ~1.0g / m} 2, decolorizer adhesion amount of decolorizing agent layer is ^{1.0g / m 2 ~10g / m 2} , also low-temperature color-forming layer the amount of adhesion, as described above, with the leuco dye adhering as dry matter, is ^{0.2g / m 2 ~0.5g / m 2} . Adhesion amount of the tube if a protective layer ^{is, 0.5g / m 2 ~5.0g / m} 2 is preferred. If an intermediate layer between the color erasing agent layer and between the low-temperature color-forming layer and or decolorizer layer and the high-temperature color-forming layer, the former is preferably ^{0.5g / m 2 ~5.0g / m 2} ,
The latter 1g / m ² ~10g / m ² is preferred.

Further, by increasing the number of thermosensitive coloring layers in the same manner as described above, a multicolor thermosensitive recording material having three or more colors can be obtained.

〔effect〕

The multicolor heat-sensitive recording material of the present invention has the above-mentioned constitution, and since the compound of the general formula (I) is used, the image stability of the low-temperature color-developing layer is remarkably improved. For example, under the condition of 60 ° C Dry for 16 hours. Also in the case of (1), there is almost no decrease in the image density of the low-temperature color-developing layer, and a multicolor-colored image excellent in color difficulty is provided.

〔Example〕

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

Examples 1 and 2 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% aqueous solution of hydroxyethyl cellulose 20〃 water 60〃 [dispersion liquid-B] 3,3'-dichlorophenylthio Urea 10 parts N-stearylbenzamide 10〃 calcium carbonate 10〃 polyvinyl alcohol 10% aqueous solution 20〃 water 50 parts [dispersion-C] 3-diethylamino-7-chlorofluorane (red) 20 parts 10% hydroxyethylcellulose aqueous solution 20〃 water 60 parts [Dispersion-D] 3,3-Dichlorophenylthiourea 10 parts Calcium carbonate 10〃 Polyvinyl alcohol 10% aqueous solution 20〃 Water 60〃 Dispersion A10 parts prepared as above, Dispersion B70 parts, water
20 parts of each was taken and mixed and stirred to obtain a thermosensitive coloring layer forming liquid for low temperature coloring. On the other hand, dispersion C10 parts, dispersion D70 parts, water
20 parts of each was 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]

Decoloring agent in Table-1 20 parts 10% aqueous solution of polyvinyl alcohol 20〃 water 60〃 Next, the high temperature thermosensitive coloring layer forming liquid (dry coating amount) on a commercial high-quality paper having a basis weight of about 52g / m ^2. 5g / m ² ), decolorizing agent layer forming liquid (dry coating amount 3 g / m ² ), intermediate layer forming liquid terpene resin latex (solid content 40%) (dry coating amount 3 g / m ² ).
m ² ), a low temperature thermosensitive color forming layer forming liquid (dry coating amount 4 g / m ² ) are successively applied and dried, and then calendered to obtain a smoothness of 500 to 1000 sec. A multicolor thermosensitive recording material was prepared.

Comparative Example In Example 1, instead of bis (N-benzyl-N-cyclohexyl) terephthalamide in the decolorizer layer forming liquid, N,
A thermal recording material for comparison was prepared in the same manner as in Example 1 except that N ', N "-triphenylguanidine was used.

The dynamic color forming characteristics of the multicolor thermosensitive recording materials of Examples and Comparative Examples obtained as described above were tested by a G-III facsimile test machine.

The test machine is 8 dots / mm from Matsushita Electronic Components Co., Ltd.
It has a thermal head, the resistance of the heating element is about 400 Ω / dot, and the color development test is a main scanning recording speed of 20 msec / line.
The sub scanning was 3.85 / mm, the platen pressure was 3.0 kg / cm ² , and the head input was 0.6 W / dot. The coloring energy was 1.0 mJ for the low temperature coloring layer and 3.3 mJ for the high temperature coloring layer.

The heat resistance was measured by measuring the low-temperature color-developing layer concentration after 16 hours passed at 60 ° C Dry.

The results are shown in Table-1.

From the above results, it is clear that the product of the present invention is a multicolor heat-sensitive recording material which is excellent in stability of a low-temperature color image and has improved heat resistance.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 61-222789 (JP, A) JP 56-40588 (JP, A) JP 57-181891 (JP, A) JP 60- 68991 (JP, A)

Claims (1)

[Claims] 1. A thermosensitive coloring layer of two or more colors having different coloring energies and coloring in different color tones are sequentially laminated on a support so that the one having a smaller coloring energy is an upper layer and each thermosensitive coloring layer. A multicolor heat-sensitive recording material having at least one decolorizing layer in which the compound having a structure represented by the following general formula (I) and having a melting point in the range of 140 to 250 ° C. is contained. Multicolor thermal recording material. (In the formula, R ₁ and R ₂ are an alkyl group, a cycloalkyl group,
Represents an aryl group or an aralkyl group. )