JPH06143823A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having high sensitivity and excellent preservability against heat, humidity by providing a thermal coloring layer containing special coloring compound and color developing compound and further methylol amide behenate on a support. CONSTITUTION:A thermal coloring layer is regulated with coloring compound expressed by a formula I, color developing compound expressed by a formula II, methylol amide behenate as a main ingredient, binder 2 such as methyl cellulose, filler such as calcium carbonate as required, the other additive, etc. The coloring layer contains 1-20 pts.wt. of the developing compound expressed by the formula II to 1 pt.wt. of the coloring compound expressed by the formula I and 0.5-20 pts.wt. of methylol amide behenate. Thus, a thermal recording material having high sensitivity, small fog against heat, wet heat and excellent preservability is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material which is excellent in color developability, heat resistance and wet heat resistance with less fog.

[0002]

2. Description of the Related Art A heat-sensitive recording material using a colorless or light-colored color-forming substance and a color-developing substance capable of coloring the color-forming substance under heat is disclosed in JP-B-43-4160 and JP-B-45-14039.
It has been widely used in practice. Generally, in a heat-sensitive recording material, a leuco dye and a color developer such as a phenolic substance are separately dispersed in fine particles, and then both are mixed, and a binder, a sensitizer, a filler, a lubricant, etc. are added thereto. It is applied as a coating solution by adding an agent and applied on a support such as paper, film, synthetic paper, etc. Color is generated by a chemical reaction that occurs when one or both of the leuco dye and the developer melts and is heated by heating. A sheet-shaped heat-sensitive recording material is usually used to obtain a record. A thermal printer or the like having a built-in thermal head is used for coloring such a thermal recording sheet. Compared to other recording methods, this heat-sensitive recording method (1) does not generate noise during recording, (2) does not require developing and fixing, etc.
(3) Maintenance free. (4) Due to features such as relatively inexpensive machines, the field of facsimiles, computer output, printers such as calculators,
It is widely used in the fields of medical measurement recorders, automatic ticket vending machines, and heat-sensitive recording labels.

[0003] Among these fields of use, labels are being used with the expansion of POS systems in retail stores, supermarkets, etc., and their use is increasing in train tickets for station automation systems. Among commercial products handled by the POS system, commercialization of instant foods or processed foods often causes labels to be exposed to heating and thawing, which causes a problem in addition to the conventional storage stability of the image area. Is that fog is caused by heat and humidity.

Further, in recent years, the demand for high-speed recording has been further increased, and the development of a heat-sensitive recording material capable of sufficiently supporting high-speed recording has been strongly desired. It is easy to appear the drawback that occurs. Conventionally, various methods have been proposed in order to improve heat resistance and heat resistance and moist heat resistance, but a satisfactory method has not been established yet.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to overcome the drawbacks of the prior art. That is, it is to provide a heat-sensitive recording material having high sensitivity and good storage stability against heat and humidity.

[0006]

The present inventor has completed the present invention as a result of various studies to achieve the above object. That is, the present invention provides a thermosensitive recording material in which a thermosensitive coloring layer containing a colorless or pale-colored coloring compound and a color-developing compound capable of coloring the coloring compound on heating is provided on the support. Formula (1)
And a compound of the following formula (2) as the color-developing compound, and further contains methylol behenic acid amide.

[0007]

[Chemical 4]

[0008]

[Chemical 5]

(In the formula (2), R is an alkyl group having 1 to 4 carbon atoms or

[Chemical 6] Represents)

The present invention will be described in detail. In the present invention, the above-described color-forming compound of the formula (1), the color-developing compound of the formula (2), and methylol behenic acid amide as main components are the following binders and other fillers if necessary, and others. The heat-sensitive color forming layer is prepared by using the additives and the like.
The ratio in the thermosensitive color developing layer is 1 to 1 part by weight of the color forming compound of the formula (1) to 1 to 1 part of the color developing compound of the formula (2).
20 parts by weight, preferably 1 to 5 parts by weight, 0.5 to 20 parts by weight of methylol behenic acid amide, preferably 2 to 10 parts by weight are suitable.

Examples of the color-forming compound are not particularly limited as long as they are generally used for pressure-sensitive recording paper and heat-sensitive recording paper. Specific examples include the following compounds. Fluoran compound; 2-aniline-3-methyl-6-
Diethylaminofluorane, 2-anilino-3-methyl-6-dibutylaminofluorane, 2-anilino-3-
Methyl-6- (N-methyl-N-cyclohexylamino) fluorane, 2-anilino-3-methyl-6- (N
-Ethyl-N-isopentylamino) fluorane, 2-
Anilino-3-methyl-6-isobutylethylaminofluorane, 2-anilino-3-methyl-6- [N-ethyl-N- (3-ethoxypropyl) amino] fluorane, 2-anilino-3-methyl-6 -(N-ethyl-N
-Hexylamino) fluorane, 2-anilino-3-methyl-6-dipentylaminofluorane, 2-anilino-3-methyl-6- (N-methyl-N-propylamino) fluorane, 2-anilino-3-methyl -6- (N
-Ethyl-N-tetrahydrofurylamino) fluorane, 2- (p-chloroanilino) -3-methyl-6-diethylaminofluorane, 2- (p-fluoroanilino) -3-methyl-6-diethylaminofluorane, 2
-Anilino-3-methyl-6- (p-toluidinoethylamino) fluorane, 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, 2- (o-chloroanilino) -6-diethylaminofluor Oran, 2-
(O-Chloroanilino) -6-dibutylaminofluorane, 2- (3,4-dichloroanilino) -6-diethylaminofluorane, 2- (o-fluoroanilino-6-
Diethylaminofluorane, 2- (o-fluoroanilino) -6-dibutylaminofluorane, 2-anilino-
3-Methyl-6-piperidinofluorane, 2-anilino-3-methyl-6-pyrrolidinofluorane, 2-ethoxyethylamino-3-chloro-6-diethylaminofluorane, 2-anilino-3-chloro -6-diethylfluorane, 2-chloro-6-diethylaminofluorane,
2-Methyl-3-chloro-6-diethylaminofluorane, 2-methyl-6-diethylaminofluorane, 2-
Octylamino-6-diethylaminofluorane, 2-
Phenyl-6-diethylaminofluorane, 2-phenethyl-3-methyl-6- (p-toluidinoethylamino) fluorane, 3-chloro-6-cyclohexylaminofluorane, 6-diethylaminobenzo [a] -fluorane, 2-methyl-6- (NP.tolyl-N-ethyl) aminofluorane, 2-anilino-6-hexylethylaminofluorane, etc.

Triarylmethane compound; 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL), 3,3-bis (p-dimethylaminophenyl) Phthalide, 3- (p-dimethylaminophenyl)-
3- (1,2-dimethylaminoindol-3-yl)
Phthalide, 3- (p-dimethylaminophenyl) -3-
(2-Methylindol-3-yl) phthalide, 3-
(P-Dimethylaminophenyl) -3- (2-phenylindol-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) -5-
Dimethylaminophthalide, 3,3- (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3
-P-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide, 3,
3-bis [2- (4-dimethylaminophenyl) -2-
(4-Methoxyphenyl) vinyl] -4,5,6,7-
Tetrachlorophthalide, etc.

Spiro compounds; 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3 '
-Dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3
-Methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'-benzopyran)
etc,

Diphenylmethane compounds; N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,
4,5-trichlorophenyl leuco auramine, etc.,

Thiazine compounds; benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.

Lactam compounds; rhodamine B anilinolactam, rhodamine B-p-chloroanilinolactam, etc.

Fluorene compounds; 3,6-Bus (dimethylamino) fluorenspyro (9,3 ')-6'-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenspyro (9,3') -6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenspiro (9,3 ')-6'-pyrrolidinophthalide and the like can be mentioned. These color-forming compounds may be used alone or in admixture of two or more.

Examples of the binder include methyl cellulose,
Methoxycellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, polyvinyl alcohol (P
VA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer , Water-soluble substances such as alkali salts of iso (or diiso) butylene / maleic anhydride copolymers, ethylene / vinyl acetate copolymers, polystyrene, polyacrylic acid esters, polyurethanes, styrene / butadiene (SB) copolymers , Carboxylated styrene / butadiene (SB)
Copolymers, styrene / butadiene / acrylic acid type copolymers, acrylonitrile / butadiene copolymers, ethylene / acrylic acid copolymers, water-soluble emulsions such as colloidal silica / acrylic resin composite particles, and the like are used.

Examples of usable fillers are calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, Urea-formalin resin and the like.

Other additives that can be used include higher fatty acid metal salts such as zinc stearate and calcium stearate, animal and vegetable wax, polyethylene wax, for the purpose of preventing thermal head wear and sticking.
Waxes such as synthetic waxes, phenol derivatives that impart antioxidant or anti-aging properties, UV absorbers such as benzophenone-based and benzotriazole-based, various surfactants,
An antifoaming agent or the like is added as needed.

The heat-sensitive recording material of the present invention is prepared using the above-mentioned material by the following method, for example. That is, according to a conventional method, a color-forming compound, a color-developing compound, and methylol behenic acid amide of the above formula (1) are separately added together with a binder or, if necessary, other additives such as a ball mill, attritor, and sand mill After pulverizing and dispersing with a disperser, they are mixed to prepare a thermosensitive color developing layer coating solution, which is usually dried at a weight of 1 to 40 g / m ² on a support such as paper, plastic sheet and synthetic paper. The thermosensitive recording material of the present invention is obtained by coating with a bar coater, blade coater or the like (the ratio of the color-forming compound to the color-developing compound is usually 1: 1 to 1:10 by dry weight). If necessary, an intermediate layer may be provided between the thermosensitive coloring layer and the support, or an overcoat layer may be provided on the thermosensitive coloring layer.

The heat-sensitive recording material of the present invention using the color-forming compound of the formula (1), the color-developing compound of the formula (2) and further methylol behenic acid amide has a higher sensitivity and heat resistance than those conventionally known. Has little fog against heat and humidity and has good storage stability.

[0023]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In the examples, "part" indicates part by weight.

Example 1 A mixture having the following composition was pulverized and dispersed using a sand grinder so as to have an average particle size of 2 μm or less, to prepare solutions [A], [B] and [C]. [A] liquid: 2-anilino-3-methyl-6-dibutylaminofluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: benzyl bis (4-hydroxyphenyl) acetate 25 parts 25% PVA aqueous solution 20 Part Water 55 parts [C] Liquid: Clover Ace KN (trade name, manufactured by Nippon Kasei Co., Ltd., methylol behenic acid amide) 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, the respective preparation liquids were mixed in the following proportions to prepare a heat-sensitive color developing layer coating liquid, which was applied onto a high quality paper having a basis weight of 50 g / m ^{2 so} that the dry weight thereof was about 7 g / m ² . It was dried to obtain the heat-sensitive recording material of the present invention. [A] liquid 10 parts [B] liquid 30 parts [C] liquid 30 parts 50% calcium carbonate dispersion 25 parts 25% PVA aqueous solution 10 parts

Example 2. A thermosensitive recording material of the present invention was prepared in the same manner as in Example 1 except that the 25% bis (4-hydroxyphenyl) methyl acetate dispersion liquid obtained by similarly pulverizing and dispersing was used in place of the liquid [B] of Example 1. Obtained.

Example 3. The heat-sensitive material of the present invention was prepared in the same manner as in Example 1 except that a 25% bis (4-hydroxyphenyl) butyl acetate dispersion obtained by similarly pulverizing and dispersing was used instead of the solution [B] in Example 2. A recording material was obtained.

Using the heat-sensitive recording material of the present invention obtained as described above, the following quality performance test was conducted.

[0029]

[Table 1] Table 1 Quality performance test Background 1) Color density 2) Heat resistance 3) Moisture and heat resistance Example 1 0.07 1.50 0.11 0.17 Example 2 0.08 1.48 0.10 0 .22 Example 3 0.08 1.48 0.12 0.38

1) Background: A value (reflection density) obtained by measuring the unprinted portion of the sample with a Macbeth reflection densitometer RD-914 type. 2) Color density: Macbeth reflection density of a sample printed with a thermal printer (D-805P) manufactured by Ishida Hoki. 3) Heat resistance: Macbeth reflection density of the unprinted part of the sample after standing in a constant temperature and humidity chamber at 70 ° C. for 24 hours. 4) Moisture and heat resistance: Macbeth reflection density of the unprinted part of the sample after standing in a thermo-hygrostat at 70 ° C. and a relative humidity of 100% for 24 hours.

As is apparent from the table, the heat-sensitive recording material of the present invention is excellent in color density, heat resistance and wet heat resistance.

[0032]

EFFECTS OF THE INVENTION A heat-sensitive recording material having high sensitivity and less storability to heat and moist heat and having good storage stability was obtained.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or pale color-developing compound and a color-developing compound as a main component capable of coloring the color-developing compound when heated. Containing a compound of the following formula (1) as a developing compound and a compound of the following formula (2) as the color-developing compound,
Further, a heat-sensitive recording material containing methylol behenic acid amide. [Chemical 1] [Chemical 2] (In the formula (2), R is an alkyl group having 1 to 4 carbon atoms or Represents)