JPH06320863A - Thermal recording material - Google Patents

Abstract

PURPOSE:To reduce background fog under a high temp. and high humidity condition, in a thermal recording material having a thermal color developing layer containing an azoic compd., adding an indenephenol resin. CONSTITUTION:A thermal recording material is characterized by that an indene- phenol resin is added to the thermal recording layer provided to a support such as paper, a plastic film or synthetic paper and excellent in the storage stability and coloring sensitivity of a coloring image.

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 coloring 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, vending machines, thermosensitive recording labels, etc. due to its relatively inexpensive machines. .

[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 is a thermosensitive recording material provided with a thermosensitive color forming layer containing a colorless or light-colored color forming compound and a color developing compound capable of coloring the color forming compound on heat on a support, containing an indene phenol resin. The present invention provides a heat-sensitive recording material characterized by the following.

The indene phenol resin used in the present invention is a reaction product of indene and phenol,
Average molecular weight 600-800, softening point 100-120 ° C
It is a compound (resin) having the following physical properties.

In the heat-sensitive recording material of the present invention, the indene phenol resin is 1 to 50 relative to the weight of the heat-sensitive recording material.
It is contained in a weight percent, preferably 2 to 30 weight percent, and is usually contained in the thermosensitive coloring layer.
It can also 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 indene phenol resin and the following color-forming compounds, color-developing compounds, binders and, if necessary, fillers, heat-fusible compounds and interfaces are used. The thermosensitive coloring layer is prepared by using an activator or the like.

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; 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-
Methyl-7-anilinofluorane, 3- (N-methyl-
N-cyclohexylamino) -6-methyl-7-anilinofluorane, 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- (p-toluidinoethylamino)
-6-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (p-toluidino) fluorane, 3-diethylamino-7- (o-chloroanilino)
Fluoran, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (3,
4-dichloroanilino) fluorane, 3-diethylamino-7- (o-fluoroanilino) fluorane, 3-dibutylamino-7- (o-fluoroanilino) fluorane, 3-pyrrolidino-6-methyl-7-ani Rinofluorane, 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-toluidinoethylamino) -6
-Methyl-7-phenethylfluorane, 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 and the like,

Spiro compounds; 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3 '
-Dichlorospirodinaphthopyran, 3-benzylcypyrrodinaphthopyran, 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-chloranilinolactam, etc., fluorene compounds; 3,6-bis (dimethyl) amino)
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 in admixture of two or more.

As the color-developing compound, those which are generally used for pressure-sensitive recording paper and heat-sensitive recording paper can be used and are 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 (also known as bisphenol A or BPA),
2,2'-bis (p-hydroxyphenyl) butane,
1,1′-bis (p-hydroxyphenyl) cyclohexane, 4,4′-thiobisphenol, 4,4′-cyclohexylidene diphenol, 2,2 ′-(2,5-dibromo-4-hydroxyphenyl) propane , 4, 4 '
-Isopropylidenebis- (2-t-butylphenol), 2,2'-methylenebis- (4-chlorophenol), 4,4'-sulfonyldiphenol, 4,4'-
Sulfonyl-bis- (2-allylphenol), 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone,
4-hydroxy-4'-butoxydiphenylyl sulfone,
Methyl bis (4-hydroxyphenyl) acetate, bis (4
-Hydroxyphenyl) butyl acetate, bis (4-hydroxyphenyl) benzyl acetate and other phenolic compounds,
Benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, 4-
Dimethyl hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3,
Examples thereof include aromatic carboxylic acid derivatives such as 5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids, and metal salts thereof.

(C) Examples of Binder 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, hydrophobic polymer 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 and 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, antifoaming agents, ultraviolet absorbers and the like are added as required.

The heat-sensitive recording material of the present invention is prepared by using the above-mentioned material by the following method, for example. That is, first by a conventional method, the color-developing compound, the color-developing compound, and the indene phenol resin are separately pulverized with a binder or a dispersing machine such as an attritor or a sand mill together with other additives as necessary, After dispersion (the indene phenol resin may be mixed with a color-forming compound or a color-developing compound in advance for dispersion), a thermosensitive coloring layer coating solution is prepared to support paper, plastic sheet, synthetic paper, etc. 1 to 20 g / m ^{2 by} dry weight on the body
To obtain the heat-sensitive recording material of the present invention by coating with a bar coater, a blade coater or the like (the ratio of the color-forming compound to the color-developing compound is usually 2: 1 to 1:10 by dry weight ratio). .

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. When the indene phenol resin is contained in the intermediate layer or the overcoat layer, the indene phenol resin is pulverized in the same manner as in the preparation of the thermosensitive color developing layer coating solution, together with the binder or other additives as necessary,
After being dispersed to form a coating solution for the intermediate layer or a coating solution for the protective layer, it is applied so that the dry weight is usually 0.1 to 30 g / m ² . The heat-sensitive recording material of the present invention containing the above-mentioned indene phenol resin is superior in storability of color image and high in color sensitivity as compared with conventionally known heat-sensitive recording materials.

[0022]

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. Liquid [A]: 2-anilino-3-methyl-6-dibutylaminofluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] Liquid: Bisphenol A 25 parts 25% PVA aqueous solution 20 parts water 55 parts [C ] Liquid: Cyclic aromatic resin I-100 (trade name; Nippon Steel Chemical Co., Ltd., indene phenol resin, average molecular weight = 600, softening point = 100 ° C.) 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 coating liquid for the thermosensitive color developing layer, which is coated on 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, the heat-sensitive 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 cyclic aromatic resin I-100 of Example 1, a cyclic aromatic resin I-120 (trade name; Nippon Steel Chemical Co., Ltd.,
An indene phenol resin, average molecular weight = 800, softening point = 120 ° C.) was used in the same manner as in Example 1 to obtain a heat-sensitive recording material of the present invention.

Example 3 Instead of the liquid [B] of Example 1, pulverization was performed in the same manner as in Example 1,
Example 1 using 25% 4-hydroxy-4'-isopropoxydiphenyl sulfone dispersion obtained by dispersion
A thermal recording material of the present invention was obtained in the same manner as in.

Example 4 Instead of the liquid [B] of Example 1, pulverization was carried out in the same manner as in Example 1,
25% 4,4′-sulfonyl-bis-obtained by dispersion
Using the (2-allylphenol) dispersion, a thermal recording material of the present invention was obtained in the same manner as in Example 1.

Example 5 A thermosensitive color developing layer coating solution having the following proportions was prepared, and the base material 5
Approximately 11 g / m ² by dry weight on 0 g / m ² high-quality paper
Was applied and dried to form a thermosensitive coloring layer. [A] liquid 6 parts [B] liquid 24 parts 50% calcium carbonate dispersion liquid 20 parts 25% PVA aqueous solution 15 parts Then, the following mixture is pulverized and dispersed using a sand grinder so that the average particle diameter becomes 2 μm or less. And liquid [E] was prepared. Solution [E]: Cyclic aromatic resin I-120 4 parts 25% PVA aqueous solution 48 parts Water 48 parts This [E] solution on the thermosensitive color developing layer has a dry weight of about 2 g / m ^2. It was coated on and dried to obtain the heat-sensitive recording material of the present invention.

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 1.41 100% 90% 85% Example 20 0.06 1.40 100% 92% 86% Example 3 0.06 1.45 100% 98% 92% Example 4 0.07 1.46 100% 100% 99% Example 5 0.06 1.40 100% 90% 90%

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 thermosensitive recording material comprising a support and a thermosensitive color-forming 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, comprising an indene phenol resin. A heat-sensitive recording material characterized by: