JPH06219056A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material reduced in background fog and excellent in image preservability. CONSTITUTION:A specific fluorane compd., a bisphenol S derivative and 4- benzyloxy-4'-(2-methylglycidyloxy)diphenylsulfone are added to the thermal color forming layer provided on a support such as paper, a plastic sheet or synthetic paper.

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 having excellent storage stability of a color image and high color density and color sensitivity.

[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 forms a coating liquid by adding an agent and is applied to a support such as paper, film, synthetic paper, etc. Color recording by a chemical reaction that occurs when one or both of the leuco dye and the developer melt and contact by heating. 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. In addition, the demand for high-speed recording and high-density recording is increasing, and it is strongly desired to develop a high-sensitivity heat-sensitive recording material capable of coping with the increase in speed of the recording apparatus.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art. That is,
Less likely to cause discoloration or discoloration due to contact with water or plastic films of colored images, low background fog under high temperature and high humidity conditions, high water resistance, high plasticizer preservability, and It is to provide a high-sensitivity heat-sensitive recording material.

[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 relates to 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 compound under heat as a main component. Containing p-menthylphenol as a polar compound, and further 4-benzyloxy-4'-
The present invention provides a heat-sensitive recording material containing (2-methylglycidyloxy) diphenyl sulfone.

The color-developing compound p-menthylphenol used in the present invention is obtained by reacting 1 mol of phenol with 1-p-menthene produced by reduction of limonene in the presence of a Friedel-Crafts type catalyst. It has a physical property value of molecular weight = about 232 and melting point = about 90 ° C., and its structure has not been sufficiently clarified, but it is considered that the compound represented by the following formula is a main component. This p
Menthylphenol is commercially available.

[0008]

[Chemical 1]

In the heat-sensitive recording material of the present invention, the ratio of the color-developing compound, p-menthylphenol, to the color-developing compound is in the range of 2: 1 to 1:10 by weight,
It is preferably 1: 1 to 1: 5. Further, 4-benzyloxy-4 '-(2-methylglycidyloxy) diphenyl sulfone is contained in the thermosensitive recording layer in an amount of 1 to 50% by weight, preferably 2 to 30% by weight, based on the weight of the thermosensitive recording material. In addition to the above, it may be contained in an intermediate layer provided between the support and the thermosensitive coloring layer or in a protective layer provided on the thermosensitive coloring layer.
As a result, a heat-sensitive recording paper having improved plasticizer resistance and oil resistance and free from background fog can be obtained.

In the heat-sensitive recording material of the present invention, the above-mentioned p-menthylphenol and 4-benzyloxy-4 'are used.
-(2-Methylglycidyloxy) diphenyl sulfone in combination with a color-forming compound as shown below, a binder and optionally a color-developing compound, a filler, a heat-fusible compound, a surfactant, etc. A thermosensitive coloring layer is prepared by.

Examples of the color-forming compound are those generally used for pressure-sensitive recording paper and heat-sensitive recording paper and are not particularly limited. Specific examples include the following compounds. Fluoran compounds; 2-anilino-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-diethylaminofluorane , 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-diethylaminofluorane, 2-chloro-6-diethylaminofluorane, 2-methyl-3-chloro-6-diethylaminofluorane, 2-methyl-6-diethylaminofluorane, 2-octylamino-6-diethylaminofluor Olane, 2-phenyl-6-diethylaminofluorane, 2
-Phenethyl-3-methyl-6- (p-toluidinoethylamino) fluorane and the like,

Triarylmethane compound; 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 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-Dimethylindole-
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-methylpyrrole-
2-yl) -6-dimethylaminophthalide, etc.

Spiro compounds; 3-methylspiro-dinaphthopyran, 3-ethylspirodinaphthopyran, 3,
3'-Dichlorospirodinaphthopyran, 3-benzylcypyrrodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8 ' −
Diphenylmethane compounds such as methoxyspiro (indoline-2,2'-benzopyran); N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ae, N-2,4,5-tri Chlorophenyl leuco auramine, etc.

Thiazine compounds; benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc., lactam compounds; rhodamine-B-anilinolactam, rhodamine B-p-chloranilinolactam, etc., fluorene compounds; 3,6-bis (Dimethylamino)
Fluorene spiro (9,3 ')-6-'dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenspiro (9,3')-6'-pyrrolidinophthalide, 3-
Dimethylamino-6-diethylaminofluorene spiro (9,3 ′)-6′-pyrrolidinophthalide] and the like. These color forming compounds may be used alone or as a mixture.

The color-developing compound which can be used in combination is generally used for pressure-sensitive recording paper and heat-sensitive recording paper and is not particularly limited. Specific examples include α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-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'-isopropyi Redene bis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (4-hydroxyphenyl) methyl acetate, bis (4-hydroxy) Phenolic compounds such as phenyl) butyl acetate, bis (4-hydroxyphenyl) benzyl acetate, benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate,
Ethyl 5-hydroxyisophthalate, 3,5-di-t-
Examples include aromatic carboxylic acid derivatives such as butylsalicylic acid and 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof.

(C) Examples of binders Methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxy group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, polyvinylpyrrolidone, poly Water-soluble acrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, aqueous isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, alkali salt of iso (or diiso) butylene / maleic anhydride copolymer, etc. Or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene / butadiene (SB) copolymer Polymers, carboxylated styrene / butadiene (SB) copolymers, styrene / butadiene / acrylic acid copolymers, water-soluble emulsions such as composite particles of colloidal silica and acrylic resin, and the like are used.

Examples of other additives: Examples of fillers include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, There are polystyrene resin, urea-formalin resin and the like.

Examples of the heat-fusible compound include waxes such as animal and vegetable wax, polyethylene wax, and synthetic wax, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, aromatic ether compounds, and aromatics. Group sulfonic acid esters, biphenyl derivatives, etc.
It is possible to use those which are solid at room temperature and have a melting point of about 80 ° C. or higher.

Specific examples of these compounds include caproic acid amide, capric acid amide, palmitic acid amide,
Stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, N-methyl stearic acid amide, stearic acid anilide, N-methyl oleic acid amide, benzanilide, linoleic acid anilide, N-ethylcaprylic acid amide, N-butyllaurin Acid amide, N-
Octadecylacetamide, N-oleinacetamide, N-oleinbenzamide, N-stearylcyclohexylamide, erucic acid amide, methylolbehenic acid amide, methylolstearic acid amide, methylenebisstearic acid amide, ethylenebisstearic 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-benzylbiphenyl, m-terphenyl, 1,5-
Bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, p-biphenyl-p-tolyl ether, benzyl-
Examples of such compounds include p-methylthiophenol, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate.

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

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, first, a color-forming compound, p-menthylphenol, 4
-Benzyloxy-4 '-(2-methylglycidyloxy) diphenyl sulfone was separately pulverized and dispersed together with a binder or, if necessary, other additives in a disperser such as a ball mill, attritor, or sand mill. 4-Benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone may be mixed with a color-forming compound or a color-developing compound in advance for dispersion) to prepare a thermosensitive color-forming layer coating solution. 1 to 20 by dry weight on a support such as paper, plastic sheet and synthetic paper.
Coating with a bar coater, a blade coater, or the like so as to be g / m ² (the ratio of the color-forming compound to the color-developing compound is usually 2: 1 to 1:10 in dry weight ratio), followed by drying to obtain the heat-sensitive material of the present invention. Obtain 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 heat-sensitive recording material of the present invention containing p-menthylphenol and 4-benzyloxy-4 '-(2-methylglycidyloxy) diphenylsulfone is superior in preservability of a color image and color development sensitivity as compared with those conventionally known. Is high.

[0023]

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 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, to prepare a liquid [A], a liquid [B] and a liquid [C], respectively. did. [A] liquid: 2-anilino-3-methyl-6-dibutylaminofluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: p-menthylphenol 25 parts 25% PVA aqueous solution 20 parts water 55 parts Liquid [C]: 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenylsulfone 25 parts 25% PVA aqueous solution 20 parts water 55 parts

Next, the respective preparation liquids are mixed in the following proportions to prepare a heat-sensitive color developing layer coating liquid, which is applied onto a high quality paper having a basis weight of 50 g / m ^{2 so} as to have a dry weight of about 13 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 [C] liquid 12 parts 50% calcium carbonate dispersion 20 parts 25% PVA aqueous solution 15 parts

Example 2 Instead of the solution [A] of Example 1, pulverization was carried out in the same manner as in Example 1,
25% 2- (o-chloroanilino) -obtained by dispersion
Using the 6-dibutylaminofluorane dispersion, a heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1.

Example 3 Instead of the liquid [A] of Example 1, pulverization was carried out in the same manner as in Example 1,
25% 2-anilino-3-methyl-6 obtained by dispersion
Using the-(N-ethyl-N-isopentylamino) fluorane dispersion, a heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1.

Example 4 Instead of the liquid [A] of Example 1, pulverization was carried out in the same manner as in Example 1,
25% 2-anilino-3-methyl-6 obtained by dispersion
Using the-(N-methyl-N-cyclohexylamino) fluorane dispersion, a thermal recording material of the present invention was obtained in the same manner as in Example 1.

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.

[0030]

Table 1 Quality performance test results Background 1) Color density 2) Heat resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 0.07 1.45 100% 100% 93% Example 20 0.06 1.42 100% 100% 90% Example 3 0.07 1.47 100% 100% 96% Example 4 0.07 1.46 100% 100% 95%

1) Background: A value (reflection density) obtained by measuring the uncolored portion of the sample with a Macbeth reflection densitometer RD-914 type. 1) Color density: Macbeth reflection density of an image portion printed by a thermal printer (D-805P) manufactured by Ishida Hoki. 2) 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. 3) Water resistance: The residual ratio (%) 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: The sample colored by the above printer was P
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 storability of a color image such as heat resistance, water resistance and plasticizer resistance and has a large color density.

[0033]

EFFECT OF THE INVENTION A heat-sensitive recording material excellent in storage stability of a color image and color development sensitivity was obtained.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive color-forming layer containing a colorless or light-colored color-forming compound and a color-developing compound capable of developing a color when the color-forming compound is heated.
A heat-sensitive recording material containing p-menthylphenol as the color-developing compound and further 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenylsulfone.