JPH06210961A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material reduced in background fog and forming a developed color image good in storage stability by providing a thermal color forming layer containing a color forming compd., a specific developer, a specific sensitizer and a specific stabilizer on a support. CONSTITUTION:A colorless or light-colored color forming compd., a terpene diphenol (developer) represented by formula I (wherein R is a 1-4C alkyl group), methylolstearamide or methylolbehenamide (sensitizer) and 4-benzyloxy-4'-(2- methylglycidyloxy)diphenylsulfone are added to and mixed with an aqueous soln. of polyvinyl alcohol being a binder under stirring in specific amts. to prepare a coating soln. for a thermal color forming layer. This coating soln. is applied to paper or a plastic film and dried to form the thermal recording layer to obtain a thermal recording material. If necessary, an intermediate layer can be provided between the thermal color forming layer and the support or an overcoat layer can be provided on the thermal color forming layer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive recording material.
More specifically, the present invention relates to a heat-sensitive recording material which is excellent in color development, has less background fog, and has high image storability.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording material is prepared by separately dispersing a leuco dye and a color developing agent such as a phenolic substance in the form of fine particles, and then mixing them together, and then adding a binder, a sensitizer and a filler. , A coating liquid prepared by adding an additive such as a lubricant, which is applied to paper, film, synthetic paper, or the like, and one or both of the leuco dye and the developer melt by heating, and a chemical reaction caused by contact causes This is to obtain a color development record. A thermal printer or the like having a built-in thermal head is used for color development of such a thermal recording sheet. Compared to other recording methods, this heat-sensitive recording method has (1) no noise during recording,
Due to the features of (2) no need for development and fixing, (3) maintenance-free, (4) relatively inexpensive machines, the field of facsimiles, computer output, printers such as calculators, medical It is widely used in the fields of measurement recorders, automatic ticket vending machines, and heat-sensitive recording labels.

Among these fields of use, the use of labels and station automation systems for train tickets is increasing with the expansion of POS systems in retail stores and supermarkets. In these applications, it is desired to further improve the storability of color images.

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 responding to high-speed recording has been strongly demanded. The drawback of fog is likely to occur. Conventionally, various methods have been proposed in order to improve thermal responsiveness and image storability, but a satisfactory method has not yet been established.

[0005]

The objects of the present invention are as follows.
It is to solve the drawbacks of the prior art. That is, it is to provide a heat-sensitive recording material having high sensitivity, less background fog, and good image storability.

[0006]

The inventors of the present invention have 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 comprising a support and a thermosensitive color-developing layer containing a colorless or light-colored color-forming compound and a color-developing compound capable of color-developing the color-forming compound when heated. The compound of the following formula (1) as a compound, methylol stearic acid amide or methylol behenic acid amide as a sensitizer, and 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone as a stabilizer are used in the thermosensitive coloring layer. Thermosensitive recording material characterized by containing

[0007]

[Chemical 3]

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

[0009]

[Chemical 4]

Stands for). The present invention will be described in detail. In the present invention, the color-forming compound, the color-developing compound of the formula (1), methylol stearic acid amide or methylol behenic acid amide, and 4-benzyloxy-4′-
The thermosensitive coloring layer is prepared by using (2-methylglycidyloxy) diphenylsulfone as a main component and a binder as shown below and other fillers and other additives as required, and the like. The compound of the formula (1) is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, and the methylolstearic acid amide or the methylol behenic acid amide is 0.5 to 20 parts by weight, preferably 1 to 5 parts by weight, relative to 1 part by weight of the color forming compound. 2 to 10 parts by weight, 4-benzyloxy-4 '-(2-methylglycidyloxy) diphenyl sulfone, 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight.

As the color-forming compound, those generally used for pressure-sensitive recording paper and heat-sensitive recording paper can be used without any particular limitation. Specific examples include the following. 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-dibutylaminofuriolane, 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-dimethylaminophenylbenzhydryl benzyl 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-bis (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 as a mixture of two or more.

Examples of binders 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 copolymer, or polyvinyl acetate / vinyl acetate copolymer, polystyrene, polyacrylic acid ester, polyurethane, styrene / butadiene (S
B) Copolymers, carboxylated styrene / butadiene (SB) copolymers, styrene / butadiene / acrylic acid copolymers, water-soluble emulsions such as composite particles of colloidal silica and acrylic resin are used.

Examples of fillers that can be used are calcium carbonate, magnesium carbonate, magnesium oxide, silica,
There are 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 are sir
Higher fatty acid metal salts such as zinc stearate and calcium stearate, animal and vegetable wax, polyethylene wax, for the purpose of preventing malhead wear and sticking.
Waxes such as synthetic waxes, phenol derivatives for imparting anti-oxidation or anti-aging properties, UV absorbers such as benzophenone-based and benzotriazole-based, various surfactants, antifoaming agents and the like are added as necessary.

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, the color-forming compound, the compound of formula (1), the methylol stearic acid amide or the methylol behenic acid amide, and 4-benzyloxy-4 ′-(2-methylglycidyl) diphenyl sulfone are separately bound to the binder or If necessary, pulverize with a disperser such as a ball mill, attritor, or sand mill along with other additives, disperse, and then mix to prepare a thermosensitive color developing layer coating solution, which supports paper, plastic sheets, synthetic paper, etc. 1 dry weight on the body
-20 g / m ² is applied by a bar coater, a blade coater or the like (the ratio of the color-developing compound to the color-developing compound is usually 1: 1 to 1:10 by dry weight) and dried. Obtain a thermosensitive recording material.

If necessary, an intermediate layer may be provided between the thermosensitive color developing layer and the support, or an overcoat layer may be provided on the thermosensitive color developing layer. The compound of formula (1) is used as a color-developing compound, and further methylol stearic acid amide or methylol behenic acid amide, 4-benzyloxy-4 ′-(2
The heat-sensitive recording material of the present invention containing -methylglucidyloxy) diphenyl sulfone in the heat-sensitive color forming layer has higher sensitivity and less background fog and better image storability than those conventionally known.

[0020]

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 that the average particle diameter was 2 μm or less, and each of [A] liquid, [B] liquid, [C] liquid and [D]. A liquid was prepared. [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 parts Water 55 parts [C] liquid: methylolstearic acid amide 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [D] liquid: 4-benzyloxy-4 ′-(2-methylglucidyloxy) diphenyl sulfone 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, the following ratios were mixed to prepare a thermosensitive color developing layer coating liquid. [A] liquid 8 parts [B] liquid 16 parts [C] liquid 20 parts [D] liquid 4 parts 50% calcium carbonate dispersion liquid 10 parts 50% carboxylated styrene-butadiene diene latex 6 parts

The coating solution for the thermosensitive color forming layer was applied on a high-quality paper having a basis weight of 50 g / m ^{2 so} that the liquid amount was about 10 g / m ^2, and dried to form a thermosensitive coloring layer. Furthermore, 10% on the thermosensitive coloring layer
The PVA aqueous solution was applied and dried so that the coating amount after drying was 3 g / m ^2, and the heat-sensitive recording material of the present invention was obtained.

Example 2 An example in which the 25% bis (4-hydroxyphenyl) methyl acetate dispersion obtained by pulverizing and dispersing in the same manner as in Example 1 was used in place of the solution [B] of Example 1 was used. A thermal recording material of the present invention was obtained in the same manner as in 1.

Example 3 A 25% bis (4-hydroxyphenyl) butyl acetate dispersion obtained by pulverizing and dispersing in the same manner as in Example 1 was used in place of the liquid [B] of Example 1 A thermal recording material of the present invention was obtained in the same manner as in 1.

Example 4 In the same manner as in Example 1 except that the liquid [C] of Example 1 was replaced by a 25% methylol behenic acid amide dispersion obtained by pulverizing and dispersing in the same manner as in Example 1. A heat-sensitive recording material of the present invention was obtained.

A quality performance test was conducted on the thermal recording material of the present invention obtained as described above, and the results are shown in Table 1.

[0028]

[Table 1] Table 1 Quality performance test Background 1) Color density 2) Heat resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 0.06 1.46 1.46 1.35 1.35 Example 2 0.07 1.44 1.44 1.30 1.32 Example 3 0.06 1.42 1.42 1.33 1.32 Example 4 0.06 1.46 1.46 1.351 .35

1) Background: A value (reflection density) obtained by measuring the uncolored portion of the sample with a Macbeth reflection densitometer RD-914 type. 2) Color density: Macbeth reflection density of the image portion printed by a thermal printer (D-805P) manufactured by Ishida Koki. 3) Heat resistance: 6 samples of color developed by the above printer
Remaining rate (%) of the density of the image area after standing for 24 hours in a thermostat at 0 ° C. 4) Water resistance: The residual ratio (%) of the density of the image area after the sample colored by the printer was immersed in tap water at room temperature for 24 hours. 5) Plasticizer resistance: P was added to the sample colored by the above printer.
0.3kg / cm with VC wrap film on both sides
The residual ratio (%) of the density of the image area after standing for 15 hours at 40 ° C. under the load of ² .

As is apparent from the table, the heat-sensitive recording material of the present invention has little background fog and is excellent in color density, and the color image thereof is excellent in heat resistance, water resistance and plasticizer resistance.

[0031]

EFFECT OF THE INVENTION A heat-sensitive recording material having high sensitivity, little background fog and good image storability was obtained.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive color-developing layer containing a colorless or pale color-developing compound and a color-developing compound capable of coloring the color-developing substance under heat as a main component. The compound of formula (1) below is used as the volatile compound, methylol stearic acid amide or methylol behenic acid amide as the sensitizer, and 4-benzyloxy-4 ′ as the stabilizer.
A heat-sensitive recording material containing-(2-methylglycidyloxy) diphenyl sulfone in a heat-sensitive color developing layer. [Chemical 1] (In the formula (1), R is an alkyl group having 1 to 4 carbon atoms or Represents )