JPH061075A - Thermal recording material - Google Patents

Abstract

PURPOSE:To improve coloring density and coloring sensitivity and enhance shelf stability by forming a thermal coloring layer containing a colorless or light-colored coloring compound and p-menthyl phenol as a developing compound coloring the coloring compound at the time of heating as main components onto a support. CONSTITUTION:p-menthyl phenol used as a developing compound is obtained by reacting 1mol phenol with 1-p-menthene generated by reducing limonene in the presence of a Friedel-Crafts' type catalyst. A thermal coloring layer is adjusted by p-menthyl phenol and a coloring compound, a binding agent and fillers, a heat-fusing compound, a surface active agent, etc., as required. The coloring compound and the developing compound are crushed and separated by a dispersion machine tother with the binding agent and another additive as required and mixed, the additive is further added as occasion calls and a thermal coloring layer coating fluid is adjusted, and the upper section of a support is coated with the coating fluid by a car coater, etc., and dried thus acquiring a thermal recording body.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heat-sensitive recording material.
More specifically, it relates to a heat-sensitive recording material using a specific compound as a developer.

[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-45-14039.
It has been widely put into practical use since it was announced in the issue. In general, 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 both.
Addition of additives such as binders, sensitizers, fillers and lubricants to form a coating solution, which is applied to a support such as paper, film or synthetic paper, and heated to produce a leuco dye and a developer. One or both of them are used to obtain a color recording by a chemical reaction that occurs when they melt or come into contact with each other, and a sheet-shaped 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 (1) does not generate noise during recording, (2) does not require developing and fixing, etc.
(3) Maintenance free. (4) Due to features such as relatively inexpensive machines, the field of facsimiles, computer output, printers such as calculators,
It is widely used in the fields of medical measurement recorders, automatic ticket vending machines, and heat-sensitive recording labels.

With the spread of such automation, the demand for high-speed recording and high-density recording has increased, and it has been strongly desired to develop not only high-speed recording devices but also recording materials that can cope with this.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heat-sensitive recording material which has sufficient color-forming sensitivity and good storability and is highly practical.

[0005]

As a result of intensive research to solve the above-mentioned problems, the present inventor has found that the above-mentioned problems can be solved by using a specific compound as a color developer, and the present invention has been completed. Let That is, the present invention provides 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 when heated. The heat-sensitive recording material is provided in which the color-developing compound is p-menthylphenol.

The present invention will be described in detail. The p-menthylphenol used as the color-developing compound in the present invention is obtained by reacting 1-p-menthene produced by the reduction of limonene with 1 mol of phenol in the presence of a Friedel-Crafts type catalyst. , Molecular weight = about 232, melting point = about 90 ° C., and its structure has not been fully elucidated, but it is considered that the compound represented by the following formula (1) is the main component. This p-menthylphenol is commercially available.

[0007]

[Chemical 1]

In the heat-sensitive recording material of the present invention, the above p
The heat-sensitive color-forming layer is prepared from menthylphenol, a color-forming compound as shown below, a binder and optionally a filler, a heat-fusible compound and a surfactant.

Examples of the color-forming compound are generally used for pressure-sensitive recording paper and heat-sensitive recording paper and are not particularly limited. Specific examples include the following compounds. 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-dibutylaminofluorane, 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, etc.,

Triarylmethane compounds; 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-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-dimethylaminophenylbenzhydrylbenzyl ae, 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-Bus (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 in admixture of two or more.

Examples of binders that can be used in the present invention include:
Methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), 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, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene /
Water-soluble substances such as alkali salts of maleic anhydride copolymers or ethylene / vinyl acetate copolymers, polystyrene,
Polyacrylic acid ester, polyurethane, styrene / butadiene (SB) copolymer, carboxylated styrene /
Butadiene (SB) copolymer, styrene / butadiene /
Examples thereof include acrylic acid-based copolymers, acrylonitrile / butadiene copolymers, ethylene / acrylic acid copolymers, and water-soluble emulsions such as composite particles of colloidal silica and acrylic resin.

In the present invention, the following additives are used as needed. Examples of other additives Filler: calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, polystyrene resin, urea-formalin resin etc.

Thermofusible compounds: waxes such as animal and vegetable waxes, polyethylene waxes, synthetic waxes and the like, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts, acetylated aromatic amines, aromatic ether compounds, aromatic sulfones. Acid esters, biphenyl derivatives, etc. that 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-methylstearic acid amide, stearic acid anilide, N-methyloleic acid amide, benzanilide, linoleic acid anilide, N-ethylcapric acid amide, N-butyl Lauric 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-
Examples include compounds such as bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate.
Other lubricants such as zinc stearate, calcium stearate, aluminum stearate, various surfactants,
An antifoaming agent, an ultraviolet absorber, etc. are added as needed.

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, according to a conventional method, the color-developing compound and the color-developing compound are separately crushed and dispersed (wet dispersion) by a disperser such as a ball mill, attritor, or sand mill together with a binder or other additives as required. In this case, usually, water is used as a medium and the proportion of solid components is adjusted to be 10 to 50% by weight), and then mixed, and if necessary, further additives are added to prepare a thermosensitive coloring layer coating solution. 1 to 40 by dry weight on a support such as paper, paper, plastic sheet, and synthetic paper.
It is applied by a bar coater, a blade coater or the like so as to have g / m ² (the ratio of the color-developing compound to the color-developing compound is usually 1: 1 to 1:10 by dry weight ratio), dried, and dried according to the present invention. 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 heat-sensitive recording material of the present invention using p-menthylphenol as a color-developing compound has high color development sensitivity, good storage stability, and high practical value.

[0022]

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 [A] liquid, a [B] liquid and a [C] liquid 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. . [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

Next, the respective preparation liquids were mixed in the following proportions to prepare a heat-sensitive color developing layer coating liquid, which was applied onto a high quality paper having a basis weight of 50 g / m ^{2 so} that the dry weight thereof was about 12 g / m ² . It was dried to obtain the heat-sensitive recording material of the present invention. [A] liquid 6 parts [B] liquid 24 parts 50% calcium carbonate dispersion 25 parts 25% PVA aqueous solution 15 parts water 30 parts

Example 2 25% 2-anilino-3-methyl-6- (N-ethyl-N-isopentylamino) fluorane obtained by similarly pulverizing and dispersing in place of the liquid [A] of Example 1 A thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the dispersion liquid was used.

Example 3 25% 2-anilino-3-methyl-6- (N-methyl-N-cyclohexylamino) fluorane dispersion obtained by similarly pulverizing and dispersing in place of the liquid [A] of Example 1 A thermal recording material of the present invention was obtained in the same manner as in Example 1 except that the liquid was used.

Example 4 A 25% 2- (o-chloroanilino) -6-dibutylaminofluorane dispersion obtained by similarly pulverizing and dispersing was used in place of the liquid [A] of Example 1 except that A thermal recording material of the present invention was obtained in the same manner as in Example 1.

Example 5 The heat-sensitive material of the present invention was prepared in the same manner as in Example 1 except that the 25% crystal violet lactone dispersion obtained by similarly pulverizing and dispersing was used instead of the solution [A] of Example 1. A recording material was obtained.

Comparative Example 1 2,2 ′ in place of the p-menthylphenol of Example 1
A thermal recording material for comparison was obtained in the same manner as in Example 1 except that-(p-hydroxyphenyl) propane was used.

Comparative Example 2 A heat-sensitive recording material for comparison was obtained in the same manner as in Example 1 except that p-hydroxybenzoic acid benzyl ester was used in place of p-menthylphenol.

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

Table 1 Quality performance test Color density 1) Heat resistance 2) Moisture resistance 3) Water resistance 4) Example 1 1.36 100% 100% 100% Example 2 1.41 100% 100% 100% Example 3 1.40 100% 100% 100% Example 4 1.35 100% 100% 100% Example 5 1.42 99% 99% 100% Comparative Example 1 1.24 98% 93% 50% Comparative Example 2 1 .35 70% 42% 29%

1) Image Density A value obtained by printing the sample with a thermal printer (D-805P) manufactured by Ishida Koki Co., Ltd. and measured with a Macbeth reflection densitometer RD-914 type. 2) Heat resistance The residual rate (%) of the color image part measured by Macbeth reflection densitometer after leaving the sample color-developed by the thermal printer in a thermostat at 60 ° C. for 24 hours. 3) Moisture resistance The residual rate (%) of the color image area measured by a Macbeth reflection densitometer after leaving the sample color-developed by the thermal printer in a humidity chamber at 40 ° C. and 90% relative humidity for 24 hours. 4) Water resistance The residual ratio (%) of the colored image portion measured by Macbeth reflection density after immersing the sample colored by the above thermal printer in tap water at room temperature for 24 hours.

As is apparent from the table, the heat-sensitive recording material of the present invention has sufficient color density and good storage stability as compared with the heat-sensitive recording material for comparison.

[0035]

The heat-sensitive recording material of the present invention has high color density and color sensitivity, is suitable for high-speed recording, and has excellent storability and extremely high practicality.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a support and a heat-sensitive color-forming layer containing a colorless or pale color-forming compound as a main component and a color-developing compound capable of coloring the color-forming compound when heated. The heat-sensitive recording material as described above, wherein the color-developing compound is p-menthylphenol.