JP3154557B2 - Thermal recording material - Google Patents

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, high color density and high 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 when heated is disclosed in JP-B-43-4160 and JP-B-45-14039.
And widely used. Generally, a thermosensitive recording material is prepared by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles separately, then mixing the two, and adding a binder, a sensitizer, a filler, a lubricant, etc. Adds an agent to form a coating liquid, and is applied to a support such as paper, film, or synthetic paper. By heating, one or both of the leuco dye and the developer are melted and colored by a chemical reaction that occurs upon contact. For recording, a heat-sensitive recording material in the form of a sheet is usually prepared. A thermal printer with a built-in thermal head or the like is used for coloring the heat-sensitive recording sheet. Compared with other recording methods, this thermal recording method (1) produces no noise during recording, (2) does not require development and fixing,
(3) Maintenance-free. (4) Facsimile field, computer output, printer field such as calculator, etc.
It is widely used in the field of recorders for medical measurement, the field of automatic ticket vending machines, the field of heat-sensitive recording labels, and the like.

[0003] Among these fields of use, the use of labels and the like with the expansion of POS systems in retail stores, supermarkets, and the like, as well as the use of tickets for station automation systems, is increasing. However, a major drawback of these methods of use is that the color image disappears or fades due to contact with plastic sheets, water wetting, or the like.

[0004] As a method of solving such a drawback, a method of applying an aqueous emulsion of a chemically resistant resin on a heat-sensitive recording layer (Japanese Patent Application Laid-Open No. 54-128347), or a method of applying a water-soluble polymer compound such as polyvinyl alcohol. (Japanese Utility Model Application Laid-Open No. 50-125354) and a method using a bisphenol derivative for the purpose of enhancing water resistance and preservation of a color image (JP-A-57-195691, JP-A-57-2051).
No. 91) has been proposed, but no satisfactory effect has been obtained. In addition, there is a demand for higher speed and higher density in an automatic system for recording and issuance, and it is strongly desired not only to increase the speed of a recording apparatus but also to develop a recording material that can cope with this.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material which is excellent in storage stability of a color image and has high color density and color sensitivity.

[0006]

The present inventor has made various studies to achieve the above object, and as a result, completed the present invention. That is, the present invention relates to a heat-sensitive recording material comprising a support, on which a heat-sensitive coloring layer mainly comprising a colorless compound having a colorless or pale color and a color-developing compound capable of causing the color-forming compound to develop a color when heated is used. Terpene diphenol and 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane or 1,
It is characterized by containing 1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane.

The present invention will be described in detail. The terpene diphenol of the color developing compound used in the present invention,
It is obtained by reacting phenol with a terpene resin such as α-pinene resin, β-pinene resin, dipentene resin in the presence of a Friedel-craft catalyst. It has a molecular weight of about 324 and a melting point of about 85 ° C. Its structure has not been fully elucidated, but it is presumed to have the following structure.
However, it is not limited to this.

[0008]

Embedded image

[0009] The 1,1,3-tris (2
-Methyl-4-hydroxy-5-t-butylphenyl)
Butane or 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane has been known to improve the storage stability of a color image, but has insufficient thermal responsiveness. I have. For example, JP-A-58-579
In No. 90, although the effect of improving moisture resistance and heat resistance can be seen, the coloring density is not sufficient. However, it has been found that when these are used together with the terpene diphenol of the present invention in the heat-sensitive color-forming layer, a high-density color-formed image can be obtained, the preservability is further improved, and a synergistic effect is obtained by the combined use. The terpene diphenol used in the present invention and 1,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane or 1,1,3-tris (2
The mixing ratio with (-methyl-4-hydroxy-5-cyclohexylphenyl) butane is in the range of 1:10 to 4: 1, preferably 1: 3 to 2: 1 by weight.

In the heat-sensitive recording material of the present invention, the above-mentioned terpene diphenol and 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane or 1,1,3-tris ( 2-methyl-4-hydroxy-
5-cyclohexylphenyl) butane in combination with a color-forming compound, a binder and other color-developing compounds as required as shown below, and a thermosensitive color-forming layer by using a filler, a heat-fusible compound, a surfactant and the like. Is prepared.

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-aniline-3-methyl-6
Diethylaminofluoran, 2-anilino-3-methyl-6-dibutylaminofluoran, 2-anilino-3-
Methyl-6- (N-methyl-N-cyclohexylamino) fluoran, 2-anilino-3-methyl-6- (N
-Ethyl-N-isopentylamino) fluoran, 2-
Anilino-3-methyl-6-isobutylethylaminofluoran, 2-anilino-3-methyl-6- [N-ethyl-N- (3-ethoxypropyl) amino] fluoran, 2-anilino-3-methyl-6 -(N-ethyl-N
-Hexylamino) fluoran, 2-anilino-3-methyl-6-dipentylaminofluoran, 2-anilino-3-methyl-6- (N-methyl-N-propylamino) fluoran, 2-anilino-3-methyl −6- (N
-Ethyl-N-tetrahydrofurylamino) fluoran, 2- (p-chloroanilino) -3-methyl-6-diethylaminofluoran, 2- (p-fluoroanilino) -3-methyl-6-diethylaminofluoran, 2
-Anilino-3-methyl-6- (p-toluidinoethylamino) fluoran, 2- (p-toluidino) -3-methyl-6-diethylaminofluoran, 2- (o-chloroanilino) -6-diethylaminofluor Oran, 2-
(O-chloroanilino) -6-dibutylaminofluoran, 2- (3,4-dichloroanilino) -6-diethylaminofluoran, 2- (o-fluoroanilino-6
Diethylaminofluoran, 2- (o-fluoroanilino) -6-dibutylaminofluoran, 2-anilino-
3-methyl-6-piperidinofluoran, 2-anilino-3-methyl-6-pyrrolidinofluoran, 2-ethoxyethylamino-3-chloro-6-diethylaminofluoran, 2-anilino-3-chloro -6-diethylfluoran, 2-chloro-6-diethylaminofluoran,
2-methyl-3-chloro-6-diethylaminofluoran, 2-methyl-6-diethylaminofluoran, 2-
Octylamino-6-diethylaminofluoran, 2-
Phenyl-6-diethylaminofluoran, 2-phenethyl-3-methyl-6- (p-toluidinoethylamino) fluoran, etc.

Triarylmethane compounds; 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also called 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 and the like,

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) and the like

Diphenylmethane compounds: N-halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl acrylate, N-2,4,
5-trichlorophenylleuco auramine and the like,

Thiazine compounds; benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc.

Lactam compounds; rhodamine B anilinolactam, rhodamine B-p-chloroanilinolactam and the like;

Fluorene compounds: 3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6'-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorenespiro (9,3') -6'-pyrrolidinophthalide, 3-dimethylamino-6-diethylaminofluorenespiro (9,3 ')-6'-pyrrolidinophthalide and the like. These color-forming compounds are used alone or in combination of two or more.

The color-developing compound that can be used in combination is not particularly limited, as it is generally used in pressure-sensitive recording paper or heat-sensitive recording paper. Specific examples include α-naphthol, β-naphthol, p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1′-bis- (p-hydroxyphenyl) propane, , 2'-bis- (p-hydroxyphenyl)
Propane, 2,2 ′-(p-hydroxyphenyl) butane, 1,1′-bis- (p-hydroxyphenyl) cyclohexane, 4,4′-thiobisphenol, 4,4 ′
-Cyclohexylidenediphenol, 2,2'-bis-
(2,5-dibromo-4-hydroxyphenyl) propane, 4,4′-isopropylidenebis- (2-t-butylphenol), 2,2′-methylenebis- (4-chlorophenol), 4,4′- Sulfonyl diphenol,
4,4′-sulfonyl-bis- (2-allylphenol), 4-hydroxy-4′-methoxydiphenylsulfone, 4-hydroxy-4′-ethoxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, 4-hydroxy-4′-butoxydiphenyl sulfone, methyl bis- (4-hydroxyphenyl) acetate, butyl bis- (4-hydroxyphenyl) acetate,
Phenolic compounds such as benzyl bis- (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate,
ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, 5-
Examples thereof include aromatic carboxylic acid derivatives such as ethyl hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, and 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids and metal salts thereof.

Examples of the binder include methylcellulose,
Methoxy cellulose, 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 derivatives thereof, casein, gelatin water-soluble isoprene rubber, styrene / maleic anhydride copolymer alkali salt Water-soluble, such as alkali salt of iso (or diiso) butylene / maleic anhydride copolymer, ethylene / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene / butadiene (SB)
Copolymer, carboxylated styrene / butadiene (S
B) Water-soluble emulsions such as copolymers, styrene / butadiene / acrylic acid copolymers, acrylonitrile / butadiene copolymers, ethylene / acrylic acid copolymers, and composite particles of colloidal silica and acrylic resin are used. .

Other additives Examples of the filler 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.

Examples of the heat-fusible compound include waxes such as animal and vegetable waxes, polyethylene waxes and synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, aromatic ether compounds, and aromatic ethers. Aromatic sulfonates, biphenyl derivatives, etc.
Those which are solid at ordinary temperature and have a melting point of about 80 ° C. or more can be used.

Specific examples of these compounds include caproic amide, capric amide, palmitic 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-ethylcapric acid amide, N-butyl Lauric amide, N-
Octadecyl acetamide, N-olein acetamide, N-olein benzamide, N-stearyl cyclohexylamide, erucamide, methylol behenamide, methylol stearamide, methylene bis stearamide, ethylene bis stearamide, 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, dibenzyl terephthalate, dibenzyl oxalate, di (4-methylbenzyl) oxalate, benzyl p-benzyloxybenzoate,
p-benzylbiphenyl, m-terphenyl, 1,5-
Compounds such as bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, phenylmesitylenesulfonate and 4-methylphenylmesitylenesulfonate are exemplified.

Other additives such as lubricants such as zinc stearate, calcium stearate, and aluminum stearate, various surfactants, defoamers, and ultraviolet absorbers are added as required.

The heat-sensitive recording material of the present invention is prepared using the above-mentioned materials by, for example, the following method. That is, first, a color-forming compound, a terpene diphenol,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane or 1,1,3-tris (2
-Methyl-4-hydroxy-5-cyclohexylphenyl) butane is separately pulverized and dispersed together with a binder or other additives as necessary with a dispersing machine such as a ball mill, an attritor or a sand mill, and then mixed. To prepare a coating solution for the thermosensitive coloring layer on a support such as paper, plastic sheet, or synthetic paper.
g / m ² with a bar coater, blade coater or the like (the ratio of the color-forming compound to the color-developing compound is usually from 1: 1 to 1:10 by dry weight ratio) and dried. A heat-sensitive recording material is obtained. 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.

Terpene diphenol is used as a color developing compound, and 1,1,3-tris (2-methyl-4-
(Hydroxy-5-t-butylphenyl) butane or 1,
The heat-sensitive recording material of the present invention using 1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane has excellent storage stability of a color-developed image as compared with conventionally known materials, and has a high color density. High coloring sensitivity.

[0026]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicates parts by weight.

Embodiment 1 FIG. A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle diameter became 2 μm or less, to prepare a solution [A], a solution [B] and a solution [C], respectively. [A] solution: 2-anilino-3-methyl-6-dibutylaminofluoran 25 parts 25% aqueous solution of PVA 20 parts water 55 parts [B] solution: terpene diphenol 25 parts 25% aqueous solution of PVA 20 parts water 55 parts [C Liquid] 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, the respective preparations are mixed in the following proportions to prepare a coating solution for the thermosensitive coloring 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 . After drying, the heat-sensitive recording material of the present invention was obtained. [A] Liquid 6 parts [B] Liquid 18 parts [C] Liquid 12 parts 50% calcium carbonate dispersion 20 parts 25% PVA aqueous solution 15 parts Water 29 parts

Embodiment 2 FIG. A 25% 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane dispersion obtained by pulverizing and dispersing in the same manner as in Example 1 was used instead of the liquid [C] in Example 1. In the same manner as in Example 1, a heat-sensitive recording material of the present invention was obtained.

Embodiment 3 FIG. In the same manner as in Example 1 except that the 25% 2- (o-chloroanilino) -6-dibutylaminofluorane dispersion obtained by pulverizing and dispersing in the same manner as in Example 2 was used instead of the solution [A] of Example 2, Thus, the heat-sensitive recording material of the present invention was obtained.

Embodiment 4 FIG. 25% 2-anilino-3- obtained by similarly pulverizing and dispersing instead of the solution [A] of Example 2
Methyl-6- (N-ethyl-N-isopentylamino)
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that a fluoran dispersion was used.

Embodiment 5 FIG. 25% 2-anilino-3- obtained by similarly pulverizing and dispersing instead of the solution [A] of Example 2
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1, except that a dispersion of methyl-6- (N-methyl-N-cyclohexylamino) fluoran was used.

Embodiment 6 FIG. A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that a 25% crystal violet lactone dispersion obtained by similarly pulverizing and dispersing the solution [A] of Example 2 was used. .

Embodiment 7 FIG. Except that 20 parts of [D] solution of the following pulverized composition solution [D] solution: N-methylol stearic acid amide 25 parts 25% PVA aqueous solution 20 parts water 55 parts were used when preparing the thermosensitive coloring layer coating solution of Example 2. In the same manner as in Example 1, a heat-sensitive recording material of the present invention was obtained.

Embodiment 8 FIG. The following pulverized composition liquid [E] liquid [E] liquid: 25 parts of 4-methylphenylmesitylenesulfonate 25 parts of a 25% PVA aqueous solution 20 parts of water 55 parts were used at the time of preparing the thermosensitive coloring layer coating liquid of Example 2. In the same manner as in Example 1, a heat-sensitive recording material of the present invention was obtained.

Comparative Example 1 In the same manner as in Example 1 except that the terpene diphenol was replaced with 2,2 '-(p-hydroxyphenyl) propane as in Comparative Example of JP-A-58-57990, except for the solution [C]. Thus, a heat-sensitive recording material for comparison was obtained.

Using the heat-sensitive recording material of the present invention obtained as described above and a heat-sensitive recording material for comparison, the following quality performance tests were carried out.

Table 1 Quality performance test Coloring density 1) Heat resistance 2) Moisture resistance 3) Water resistance 4) Plasticizer resistance 5) Example 1 1.38 100% 100% 100% 88% Example 2 1.36 100% 100% 100% 85% Example 3 1.34 100% 100% 100% 83% Example 4 1.42 100% 100% 100% 94% Example 5 1.36 99% 99% 100% 92% Example 6 1.44 99% 99% 100% 85% Example 7 1.32 100% 100% 100% 88% Example 8 1.44 100% 100% 100% 89% Comparative Example 1 1.25 98% 93% 50% 21%

1) Color density A sample was colored with a thermal printer (D-805P) manufactured by Ishida Koki Co., Ltd. The density was measured by a Macbeth reflection densitometer RD-914. 2) Heat resistance After the sample developed by the thermal test printer was left in a thermostat at 60 ° C. for 24 hours, the residual ratio (%) of the developed image portion was measured by a Macbeth reflection densitometer. 3) Moisture resistance The color development image portion was measured by a Macbeth reflection densitometer after the sample developed by the above thermal printer was left in a humidity chamber at 40 ° C. and a relative humidity of 90% for 24 hours. 4) Water resistance The residual rate (%) of the colored image area measured by Macbeth reflection density after immersing the sample colored with the above thermal test printer in tap water at room temperature for 24 hours. 5) Plasticizer resistance The sample colored with the above thermal printer is overlaid on both sides with a PVC wrap film, and about 100 g
/ Left rate of the color image area measured by a Macbeth reflection densitometer after standing at room temperature for 15 hours under a load of / cm ² (%).

As is clear from the table, the heat-sensitive recording material of the present invention is superior to the comparative heat-sensitive recording material in the preservability of color images such as heat resistance, water resistance and plasticizer resistance, and the color density. Is high.

[0041]

As described above, a heat-sensitive recording material having excellent storage stability of a color image, high color density, and high color sensitivity was obtained.

Claims (1)

(57) [Claims] 1. A heat-sensitive recording material comprising a support and a thermosensitive coloring layer mainly comprising a colorless or pale-colored coloring compound and a coloring compound capable of coloring the coloring compound when heated. Terpene diphenol and 1,1 as coloring compounds
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane or 1,1,3-tris (2
-Methyl-4-hydroxy-5-cyclohexylphenyl) butane.