JPH05345482A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance storage stability, developed color density and color forming sensitivity by adding terpene diphenol and a bisphenol monosulfide compd. represented by a specific general formula as a developer in a thermal recording material for a facsimile. CONSTITUTION:As a developing compd. forming a thermal color forming layer along with a color forming compd., terpene diphenol and a bisphenol monosulfide compd. represented by formula I (wherein R1-R4 are independently or simultaneously a hydrogen atom, a hydroxyl group, a halogen atom, a 5C or less alkyl group, an alkoxy group or an alkenyl group), for example, bis-(4,4'- hydroxyphenyl)sulfide are added. A binder such as methyl cellulose and additives are added and the wt. ratio of terpene diphenol and the bisphenol sulfide compd. represented by the formula I is pref. 4:1-1:4.

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 coloring substance and a color-developing substance capable of coloring the coloring substance under heat is disclosed in JP-B-43-4160 and JP-B-45-14039.
It has been widely used in practice. 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 applied as a coating solution by adding an agent and applied on a support such as paper, film, synthetic paper, etc. Color is developed by a chemical reaction that occurs when one or both of the leuco dye and the developer melts and is heated by heating. A heat-sensitive recording material for obtaining a record and usually in the form of a sheet is prepared. A thermal printer or the like having a built-in thermal head is used for coloring such a thermal recording sheet. Compared with other recording methods, this heat-sensitive recording method (1) does not generate noise during recording, (2) does not require development 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.

[0003] Among these fields of use, the use of labels is increasing with the expansion of POS systems at retail stores, supermarkets, etc., and 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 resin having chemical resistance on the heat-sensitive recording layer (JP-A-54-128347) and a water-soluble polymer compound such as polyvinyl alcohol are coated. Method (Jpn. Pat. Appln. KOKAI No. 50-125354), or a method of using a bisphenol derivative for the purpose of enhancing water resistance and storability of color image (JP-A-57-195691 and JP-A-57-2051).
No. 91) has been proposed, but the satisfactory effect has not been obtained. In addition, there is a demand for higher speed and higher density in an automated system for recording, issuing, etc., and it is strongly desired to develop a recording material capable of coping with the speedup of the recording apparatus.

[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 inventors have completed the present invention as a result of various studies to achieve the above object. That is, the present invention provides a thermosensitive recording material having a thermosensitive coloring layer containing a colorless or light-colored coloring compound and a color-developing compound capable of coloring the coloring compound on heating, as a main component. A terpene diphenol and a bisphenol monosulfide compound represented by the following formula (1) are contained as color-developing compounds.

[0007]

[Chemical 2] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ independently or simultaneously represent a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group having 5 or less carbon atoms, an alkoxy group or an alkenyl group.)

The present invention will be described in detail. With 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 and dipentene resin in the presence of a Friedel-Crafts type catalyst. It has a molecular weight of about 324 and a melting point of about 85 ° C. Its structure has not been fully clarified, but it is presumed to have the following structure. However, it is not limited to this.

[0009]

[Chemical 3]

The compounds of formula (1) used at the same time are
It is a bisphenol monosulfide-based compound, and specific examples include bis- (4,4'-hydroxyphenyl) sulfide, bis- (3,5-dimethyl-4-hydroxyphenyl) sulfide and bis- (2,5-dimethyl- 4-
Hydroxyphenyl) sulfide, bis- (2-methyl-5-isopropyl-4-hydroxyphenyl) sulfide, bis- (2-methyl-5-t-butyl-4-hydroxyphenyl) flufide, bis- (3-methyl −
4-hydroxyphenyl) sulfide, bis- (3-isobutyl-4-hydroxyphenyl) sulfide, bis- (3-t-butyl-4-hydroxyphenyl) sulfide, bis- (3-cyclohexyl-4-hydroxyphenyl) sulfide, etc. Is mentioned.

In the heat-sensitive recording material of the present invention, the above-mentioned terpene diphenol and the compound of the formula (1), a color-forming compound as shown below, a binder and optionally a filler, a heat-fusible compound, an interface The thermosensitive coloring layer is prepared by using an activator or the like. Terpene diphenol and formula (1)
The use ratio of the compound can be changed arbitrarily, but it is 4: 1 to 1:
A weight ratio of 4 is preferred.

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 compounds; 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 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), 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-bis (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 include methyl cellulose,
Methoxycellulose, 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 its derivatives, casein, gelatin water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer , Water-soluble compounds such as alkali salts of iso (or diiso) butylene / maleic anhydride copolymer, or ethylene / vinyl acetate copolymer, polystyrene, polyacrylic ester, polyurethane, styrene / butadiene (SB)
Copolymer, carboxylated styrene / butadiene (S
B) Copolymers, styrene / butadiene / acrylic acid type copolymers, acrylonitrile / butadiene copolymers, ethylene / acrylic acid copolymers, water-soluble emulsions such as colloidal silica / acrylic resin composite particles, etc. are used. ..

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 are used.

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 sulfonates, 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-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 thereof include compounds such as bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, phenylmesitylene sulfonate, and 4-methylphenylmesitylene sulfonate.

In addition, lubricants such as zinc stearate, calcium stearate and aluminum stearate, various surface active agents, 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, by a conventional method, the color-developing compound and the color-developing compound are separately pulverized and dispersed separately in a dispersing machine such as a ball mill, an attritor, or a sand mill together with a binder or, if necessary, other additives and the like, A thermosensitive color developing layer coating solution is prepared by mixing and is coated on a support such as paper, a plastic sheet, and synthetic paper with a bar coater, a blade coater, etc. so that the dry weight is usually 1 to 40 g / m ^2. The ratio of the color-forming compound to the color-developing compound is usually 1: 1 to 1: 1 by dry weight ratio.
(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. The heat-sensitive recording material of the present invention which uses terpene diphenol and the compound of formula (1) as the color-developing compound has excellent storage stability of a color image and high color density and color sensitivity as compared with the conventionally known materials.

[0026]

EXAMPLES The present invention will be described more specifically by way of examples, but the present invention is not limited thereto. In the examples, "part" indicates part by weight.

Example 1. The 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]. [A] liquid: 2-anilino-3-methyl-6-dibutylaminofluorane 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: terpene diphenol 25 parts 25% PVA aqueous solution 20 parts water 55 parts [C ] Liquid: bis- (3,3-dimethyl-4-hydroxyphenyl) sulfide 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 coated on 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 12 parts [C] liquid 12 parts 50% calcium carbonate dispersion 25 parts 25% PVA aqueous solution 15 parts water 30 parts

Example 2. The same procedure as in Example 1 was repeated except that the 25% bis- (2-methyl-5-t-butyl-4-hydroxyphenyl) sulfide dispersion obtained by pulverizing and dispersing was used instead of the [C] solution in Example 1. A thermal recording material of the present invention was obtained in the same manner as in Example 1.

Example 3. Instead of the liquid [C] of Example 1, 25% bis- (4,4'-) was obtained by pulverizing and dispersing in the same manner.
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the hydroxyphenyl) sulfide dispersion liquid was used.

Example 4. In the same manner as in Example 1 except that the 25% bis- (3-cyclohexyl-4-hydroxyphenyl) sulfide dispersion liquid obtained by similarly pulverizing and dispersing was used instead of the liquid [C] in Example 1. A heat-sensitive recording material of the present invention was obtained.

Example 5. 25% 2-anilino-3 obtained by similarly pulverizing and dispersing instead 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 -methyl-6- (N-ethyl-N-isopentylamine) fluorane dispersion was used.

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

Example 7. A thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the following [D] liquid obtained by similarly pulverizing and dispersing was used in place of the [C] liquid of Example 1. Liquid [D]: Bis- (2,5-dimethyl-4-hydroxyphenyl) sulfide 20 parts N-methylolstearic acid amide 20 parts 25% PVA aqueous solution 20 parts water 40 parts

Comparative Example 1. A thermosensitive recording material for comparison was obtained in the same manner as in Example 1 except that terpene diphenol was removed in Example 1.

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

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) Plasticizer resistance 5) Example 1 1.43 100% 100% 100% 95% Example 2 1.40 100% 100% 100% 99% Example 3 1.47 100% 100% 100% 99% Example 4 1.41 100% 100% 100% 99% Example 5 1.46 100% 100% 100% 96% Example 6 1.45 100% 100% 100% 95% Example 7 1.45 100% 100% 100% 97% Comparative Example 1 1.35 98% 97% 62% 95% Comparative Example 2 1.35 98% 95% 90% 35%

1) Coloring Density A sample was colored with a thermal printer (D-805P) manufactured by Ishida Koki Co., Ltd., and the density was measured by a Macbeth reflection densitometer RD-914 type. 2) Heat resistance The residual rate (%) of the color image portion measured by a Macbeth reflection densitometer after leaving the sample colored by the above thermal test printer in a thermostat at 60 ° C. for 24 hours. 3) Moisture resistance The residual rate (%) of the color image portion measured by a Macbeth reflection densitometer after leaving the sample colored by the above thermal printer in a humidity chamber at 40 ° C. and 90% relative humidity for 24 hours. 4) Water resistance The residual rate (%) of the colored image portion measured by Macbeth reflection density after immersing the sample developed by the 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 to give about 100 g.
The residual ratio (%) of the color image portion measured with a Macbeth reflection densitometer after left for 15 hours at room temperature under a load of / cm 2.

As is apparent from the table, the heat-sensitive recording material of the present invention is superior to the heat-sensitive recording material for comparison in terms of heat resistance, water resistance, plasticizer resistance and the like, and is excellent in storability of a color image and has a color density. Is high.

[0041]

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

Claims (1)

[Claims] 1. 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 as a main component capable of coloring the color-developing compound under heat. A thermosensitive recording material comprising a terpene diphenol and a bisphenol monosulfide compound represented by the following formula (1) as a color compound. [Chemical 1] (In the formula, R ₁ , R ₂ , R ₃ and R ₄ independently or simultaneously represent a hydrogen atom, a hydroxyl group, a halogen atom, an alkyl group having 5 or less carbon atoms, an alkoxy group or an alkenyl group.)