JPH07266712A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material hard to cause the wetting of a developed color image with water or the erasure or fading of a color caused by the contact with a plastic film and reducing background fog under a high temp. and high humidity condition by adding a specific color forming compd. and a specific coupling compd. to a thermal color forming layer. CONSTITUTION:In a thermal recording material wherein a thermal color forming layer containing a colorless or light-colored color forming compd. and a coupling compd. allowing the color forming compd. to form a color at the time of heating as principal components is provided on a support, as the color forming compd., a compd. represented by formula (wherein X is a halogen atom and Y is a 1-4C alkyl group) is added and, as the coupling compd., 3,4-dihydroxyphenyl-p- tolylsulfone is added. The proper use amt. of 3,4-dihydroxyphenyl-p-tolylsulfone is 0.5-10 pts.wt., pref., 1-5 pts.wt. per 1 pt.wt. of the color forming compd. represented by the formula.

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 excellent in storage stability of color images and whiteness of the background.

[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-451403.
It was announced in No. 9 and has been put to practical use. 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 used as a coating liquid by adding a chemical agent, and is applied to a support such as paper, film, synthetic paper, etc., and color recording is made by a chemical reaction that occurs when one or both of the leuco dye and the developer melts and contacts when heated. And a sheet-like heat-sensitive recording material is usually prepared. 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 is (1) no noise is generated during recording, (2) there is no need for developing and fixing, (3) maintenance-free, (4)
It is widely used in the field of facsimiles, computer output, printers such as calculators, recorders for medical measurement, ticket vending machines, thermosensitive recording labels, etc. due to the fact that machines are relatively inexpensive. .

[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. However, their use is a major drawback in that the color image disappears or fades due to contact with plastic sheets or water wetting.

As a method for solving such a drawback, a method of coating an aqueous emulsion of a chemically resistant resin on the heat-sensitive recording layer (JP-A-54-128347) and a method of coating a water-soluble polymer compound such as polyvinyl alcohol. (Actual development No. 50-125354), or a method of using a bisphenol derivative for the purpose of improving water resistance and storability of a color image (JP-A-57-195691, JP-A-57-20519).
1), a method using a novolac epoxy resin (Japanese Patent Laid-Open No. 2-289378), etc. have been proposed, but no sufficiently satisfactory effect has been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art. That is,
To provide a heat-sensitive recording material having high water resistance and high plasticizer property, which is unlikely to be discolored or discolored due to wetness of a color image or contact with a plastic film or the like, has little background fog under high temperature and high humidity conditions. It is in.

[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 (1) a thermosensitive recording material comprising a support and a thermosensitive coloring layer containing, as a main component, a colorless or light-colored coloring compound and a color-developing compound capable of coloring the coloring compound under heat. In the formula, the color-forming compound is represented by the following formula (1)

[0007]

[Chemical 2]

(Wherein X represents a halogen atom and Y represents an alkyl group having 1 to 4 carbon atoms), and 3,4-dihydroxyphenyl-p-tolylsulfone is contained as the color-developing compound. A heat-sensitive recording material, characterized by comprising:

In the formula (1), X is, for example, a fluorine atom, chlorine atom, bromine atom or iodine atom, and Y is, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group or n. -Butyl group, isobutyl group, t-butyl group and the like can be mentioned. Preferred examples of X include a fluorine atom and a chlorine atom, and examples of Y include an ethyl group and an n-butyl group. Specific examples of the color forming compound represented by the formula (1) include, for example, 3-diethylamino-7- (o-fluoroanilino).
Fluorane, 3-di-n-butylamino-7- (o-fluoroanilino) fluorane, 3-diethylamino-7
Examples thereof include-(o-chloroanilino) fluorane and 3-di-n-butylamino-7- (o-chloroanilino) fluorane.

The heat-sensitive recording material of the present invention contains the color-forming compound of the formula (1) and 3,4-dihydroxyphenyl-p-tolylsulfone, and contains the following binder and other optional fillers. The heat-sensitive color forming layer is prepared with other additives. 1 of the chromogenic compound of formula (1)
It is suitable to use 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight of 3,4-dihydroxyphenyl-p-tolylsulfone, based on parts by weight.

In forming the thermosensitive coloring layer in the present invention, the coloring compound of the formula (1) is contained in an amount of 1 to 50% by weight, 3,4
-Dihydroxyphenyl-p-tolyl sulfone is 0.5
-80% by weight, for example, 0 to 40% by weight each of the following color-forming compounds and color-developing compounds which can be used in combination, and the binder is 1
~ 90% by weight, the filler and the heat-fusible compound are each 0-8
0% by weight, other lubricants, surfactants, antifoaming agents, UV absorbers, etc., in arbitrary proportions, for example, 0 to 30% by weight,
Used (% by weight is the weight ratio of each component in the thermosensitive coloring layer).

Examples of the color-forming compound other than the color-forming compound of the formula (1) that can be used in combination are not particularly limited as long as they are those commonly used for pressure-sensitive recording paper and heat-sensitive recording paper. Specific examples include fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds and the like.

Examples of fluoran compounds include 3-
Diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino Fluoran, 3- (N
-Ethyl-N-isopentylamino) -6-methyl-7
-Anilinofluorane, 3-isobutylethylamino-
6-Methyl-7-anilinofluorane, 3- [N-ethyl-N- (3-ethoxypropyl) amino] -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-
Hexylamino) -6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-propylamino)
-6-Methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurylamino) -6-methyl-
7-anilinofluorane, 3-diethylamino-6-methyl-7- (p-chloroanilino) fluorane, 3-diethylamino-6-methyl-7- (p-fluoroanilino) fluorane, 3- (p-toluidi Noethylamino)
-6-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (p-toluidino) fluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-pyrrolidino- 6-methyl-7-
Anilinofluorane, 3-diethylamino-6-chloro-7-ethoxyethylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino- 6-chloro-7-methylfluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-phenylfluorane, 3- (p-toluidinoethyl) Amino) -6-methyl-7-phenethylfluorane and the like can be mentioned.

Examples of the triarylmethane compound include 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-dimethylaminoindole-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-ethylcarbazole-3
-Yl) -5-dimethylaminophthalide, 3,3- (2
-Phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-
(1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like can be mentioned.

Examples of the spiro compound include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-
Benzylcypyrodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'- Examples of the diphenylmethane compound include N-halophenyl-leukoauramine, 4, and the like.
4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-2,4,5-trichlorophenyl leuco auramine and the like, and thiazine compounds such as benzoyl leuco methylene blue and p-nitrobenzoyl leuco methylene blue are lactams. Examples of the system compound include rhodamine B anilinolactam and rhodamine B-p-chloroanilinolactam, and examples of the fluorene compound include 3,6-bis (dimethylamino) fluorenspyro (9,3 ′)-6- 'Dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenspyro (9,3')-6'-pyrrolidinophthalide,
Examples thereof include 3-dimethylamino-6-diethylaminofluorene spiro (9,3 ′)-6′-pyrrolidinophthalide. These color forming compounds may be used alone or as a mixture.

Further, 3,4-dihydroxyphenyl-p-
Examples of the color-developing compound that can be used in combination with tolyl sulfone include, for example, α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, and p-octylphenol.
t-butylphenol, p-phenylphenol, 1,
1'-bis (p-hydroxyphenyl) propane, 2,
2-bis (p-hydroxyphenyl) propane (bisphenol A), 2,2'-bis (p-hydroxyphenyl) butane, 1,1'-bis (p-hydroxyphenyl) cyclohexane, 4,4'-thiobisphenol <
4,4'-Cyclohexylidene diphenol, 4,4 '
-Sulfonyldiphenol, 4,4'-sulfonyl-bis (2-allylphenol), 2,2'-bis (2,5
-Dibromo-4-hydroxyphenyl) propane, 4,
4'-isopropylidene bis (2-t-butylphenol), 2,2'-methylene bis (4-chlorophenol), 4-hydroxy-4'-isoproponididiphenyl sulfone, methyl bis (4-hydroxyphenyl) acetate, Phenolic compounds such as butyl bis (4-hydroxyphenyl) acetate and benzyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, 4-hydroxyphthalate Aromatic carboxylic acid derivatives such as dimethyl acid, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof Etc.

Examples of binders that can be used include, for example, methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, polyvinyl alcohol (PVA), carboxy group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinyl. Pyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin,
Aqueous solution such as aqueous isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, alkali salt of iso (or diiso) butylene / maleic anhydride copolymer, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer Polymer, polystyrene, polyacrylate, polyurethane,
Styrene / butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene /
A butadiene / acrylic acid-based copolymer, a hydrophobic polymer emulsion such as colloidal silica-acrylic resin composite particles, and the like are used.

Examples of fillers that can be used are calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide,
Examples include barium sulfate, polystyrene resin, urea-formalin resin and the like.

Examples of heat-fusible compounds that can be used include waxes such as animal and vegetable waxes, polyethylene wax, and synthetic wax, and higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, and aromatic amines. It is possible to use an ether compound, an aromatic sulfonic acid ester, a biphenyl derivative and the like which are solid at room temperature and have a melting point of about 80 ° C. or higher.

Specific examples of these heat-fusible compounds include caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, and N-methylstearic acid amide. , Stearic acid anilide, N-methyl oleic acid amide, benzanilide, linoleic acid anilide,
N-ethylcaprylic acid amide, N-butyllauric acid amide, N-octadecylacetamide, N-oleinacetamide, N-oleinbenzamide, N-stearylcyclohexylamide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebis Stearic acid amide, ethylenebis stearic acid amide, p-acetotoluidide, polyethylene glycol, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid, 1,2-
Bis (3-methylphenoxy) ethane, 1,2-bis (4-methoxyphenoxy) ethane, 1,2-bis (3,4-dimethylphenyl) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane , 1-phenoxy-2- (4-methoxyphenoxy) ethane, 1- (2
-Methylphenoxy) -2- (4-methoxyphenoxy) ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, p-benzyloxybenzoic acid benzyl ester, p-benzyl Biphenyl, m-terphenyl,
1,5-bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, p-biphenyl-p-tolyl ether,
Examples include compounds such as benzyl-p-methylthiophenol, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate.

In addition, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surfactants, antifoaming agents, ultraviolet absorbers and the like are added as required.

The heat-sensitive recording material of the present invention is prepared by the following method using the above materials. That is, according to a conventional method, the color-forming compound of the formula (1) and 3,4-dihydroxyphenyl-p-tolylsulfone are separately added together with a binder or, if necessary, other additives such as a ball mill, an attritor or a sand mill. After pulverizing and dispersing with a disperser (when pulverizing and dispersing is wet, water is usually used as a medium) and then mixed to prepare a thermosensitive color developing layer coating solution, which is used to support paper, plastic sheet, synthetic paper, etc. It is applied to the body by a bar coater, a blade coater, etc. so that the dry weight is usually 1 to 20 g / m ² (the ratio of the color forming compound to the color developing compound is usually about 2: 1 to the dry weight ratio).
It is dried (about 1:10) to obtain the heat-sensitive recording material of the present invention.

If desired, 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. Formula (1) obtained by the above method
Color forming compound and 3,4-dihydroxyphenyl-p
-The heat-sensitive recording material of the present invention containing tolyl sulfone,
There is no background fog and the storability of colored images is excellent.

[0024]

EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In addition, "part" in an Example shows a weight part.

Example 1 A mixture [A] and a solution [B] were prepared by pulverizing and dispersing a mixture having the following composition using a sand grinder so that the average particle diameter was 2 μm or less. : 3-diethylamino-7- (o-fluoroanilino) fluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: 3,4-dihydroxyphenyl-p-tolylsulfone 25 parts 25% PVA aqueous solution 20 parts 55 parts of water

Next, the respective preparation solutions are mixed in the following proportions to prepare a coating solution for the thermosensitive color developing layer, which is applied onto a high quality paper having a basis weight of 50 g / m ² to a dry weight of about 12 g / m ² and dried. Then, a heat-sensitive recording material of the present invention was obtained. [A] liquid 6 parts [B] liquid 24 parts 50% calcium carbonate dispersion 20 parts 25% PVA aqueous solution 15 parts

Example 2 Instead of the liquid [A] of Example 1, pulverization was carried out in the same manner as in Example 1,
3-di-n-butylamino-7- (o-obtained by dispersion
A thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that 25% dispersion of fluoroanilino) fluorane was used.

Example 3 Instead of the liquid [A] of Example 1, pulverization was carried out in the same manner as in Example 1,
A 25% dispersion of 3-diethylamino-7- (o-chloroanilino) fluorane obtained by dispersion was used in the same manner as in Example 1 to obtain a heat-sensitive recording material of the present invention.

Example 4 Instead of the liquid [A] of Example 1, pulverization was carried out in the same manner as in Example 1,
3-di-n-butylamino-7- (o-obtained by dispersion
A thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that 25% dispersion of chloroanilino) fluorane was used.

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.

[0031]

Table 1 Quality performance test results Background 1) Color density 2) Heat resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 0.06 1.45 100% 97% 100% Example 20 .05 1.45 100% 98% 100% Example 3 0.06 1.44 100% 95% 100% Example 4 0.05 1.47 100% 96% 100%

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 rate (%) of the density of the image area after the sample developed 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.
The residual rate (%) of the density of the image area after leaving the VC wrap film on both sides and leaving it at 25 ° C. for 24 hours under a load of 30 g / cm ² .

As can be seen from the table, the heat-sensitive recording material of the present invention is excellent in heat-resisting property, water-resisting property, plasticizer-resisting property and the like and excellent in storability of a color image.

[0034]

EFFECTS OF THE INVENTION A heat-sensitive recording material excellent in storage stability of a color image without background fog was obtained.

Claims (1)

[Claims] 1. A thermosensitive recording material comprising a support and a thermosensitive coloring layer containing a colorless or light-colored coloring compound and a color-developing compound capable of coloring the coloring compound under heat as a main component. A heat-sensitive recording material comprising a compound represented by the following formula (1) as a photosensitive compound and 3,4-dihydroxyphenyl-p-tolylsulfone as the color-developing compound. [Chemical 1] (In the formula, X represents a halogen atom and Y represents an alkyl group having 1 to 4 carbon atoms.)