JPS61146593A - Thermal recording paper - Google Patents

Abstract

PURPOSE:To improve the ground color of a thermal recording paper under high-temperature and high-humid atmospheres by the combined use of a specific phthalic acid monobenzyl ester metal salt as a stabilizer for a specific 4- methyl-4'-hydroxydiphenylsulfone. CONSTITUTION:An organic developer, 4-methyl-4'-hydroxydiphenyl sulfone of the general formula (I), and a stabilizer, phthalic acid monobenzyl ester metal salt of the general formula (II), are used in combination. The kinds and amounts of the organic developer, a basic colorless dye, the stabilizer, and other components to be used may be properly determined in accordance with recording requirements, although not limited particularly. An aimed thermal recording paper is obtained by coating a coating liquid composed of these components on a various kinds of films. In the formula (II), M is Ca or Zn atom.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermosensitive recording paper having excellent oil and fat resistance and storage stability.

(Prior art) Thermosensitive recording paper that utilizes a color-forming reaction by heating between a so-called basic colorless dye, which is normally colorless or light-colored, and an organic color developer such as phenol or organic acid is disclosed in Japanese Patent Publication No. 43-4160 and Japanese Patent Publication No. 45
-14039, Japanese Patent Application Laid-Open No. 48-27736, etc., and has been widely put into practical use. Generally, heat-sensitive recording paper is produced by separately grinding and dispersing a basic colorless dye and an organic color developer into fine particles, and then mixing the two to form a binder, filler, sensitivity enhancer, lubricant, and other auxiliaries. A coating solution obtained by adding .sup. is applied to a support such as paper or film, and a color recording is obtained by an instantaneous chemical reaction upon heating.

In this case, various hues can be obtained by selecting the type of colorless dye.

These thermal recording papers are being applied to a wide range of fields, including measurement recorders in the medical and industrial fields, combiators, information communication terminals, facsimile machines, printers for electronic desk calculators, and automatic ticket vending machines. , clear records with high density can be obtained, there is no problem such as lees adhesion or sticking to the thermal head, excellent recording suitability, and basic quality such as little or no background color development over time. Improvement is required.

JP-A No. 59-96991 meets this demand, and it is clear that thermal recording paper using 4-methyl-4'-hydroxydiphenylsulfone as a color developer is extremely excellent in the above basic qualities. is being used.

On the other hand, thermal recording paper cannot avoid being touched by human hands due to its function as information recording paper. Since oily substances such as
It can be said that there are many chances that thermal recording paper is contaminated by these oily substances. However, in general, thermal recording paper is not sufficiently stable against these oily substances, and the density of the colored image in the contaminated area may decrease or disappear, and the phenomenon of discoloration when the white background area becomes contaminated has also been observed. It will be done.

The cause of these problems has not been fully elucidated, but the oily substance may partially dissolve the color-forming layer formed by fine particles of basic colorless dye and an organic color developer or its color-forming reaction product9. This is thought to be to create a safe state.

As mentioned above, thermal recording paper using 4-methyl-4'-hydroxydiphenylsulfone as a color developer has excellent basic quality, but on the other hand, its stability against oily substances has made it difficult to use in general. It was found that it is slightly inferior to bisphenol A.

Regarding bisphenol coloring agents, as a method for improving storage stability such as hardening agent resistance, Japanese Patent Application Laid-Open No. 57-6795
No. 2, it is proposed to use a metal salt of an aliphatic carboxylic acid or a metal salt of an aromatic carboxylic acid in combination. However, for thermal recording paper that uses 4-methyl-4'-hydroxydiphenylsulfone as a color developer, even if these carboxylic acid metal salts are combined, the stability against oily substances is only #1.
1. There was no improvement at all, but rather a decline in the background color and storage stability of the image was observed.

(Problems to be Solved by the Invention) The present invention is directed to thermal recording paper using 4-methyl-4'-hydroxydiphenylsulfone as an organic color developer, which impairs its excellent basic quality, especially the stability of the background color. At the same time, the aim is to improve the stability of the colored image against the adhesion of hair styling products and oils and fats, and the stability of the background color under conditions of high temperature and high humidity.

(Means for solving the problem) The above problem is solved by using phthalate as a stabilizer, which is represented by the following general formula (II), for 4-methyl-4'-hydroxydiphenylsulfone represented by the following general formula (I). The problem was solved by using an acid monobenzyl ester metal salt in combination.

HO+ 80□+CH3... (I) (However,
In general formula (II), M represents a calcium atom or a zinc atom. ) The organic color developer 4-methyl-4'-hydroxydiphenylsulfone used in the present invention is a compound with a melting point of 130 to 145°C. Monobenzyl phthalate ester metal salt is a high melting point substance (melting point of 250° C. or higher) obtained by the reaction of sodium salt of monobenzyl phthalate with calcium chloride or zinc sulfate.

The above-mentioned stabilizer used in the present invention is a compound having a specific molecular structure selected from among many organic carboxylic acid metal salts. These stabilizers are 10 to 10% of the organic color developer 4-methyl-4'-hydroxydiphenylsulfone
It is preferable to add in an amount of 60% by weight. If it is less than 10% by weight, it is too small and has little effect, while if it exceeds 60% by weight, there is a risk of a decrease in color density due to the dilution effect and problems with sticking.

The basic colorless dye used in the present invention is not particularly limited, but tri7-ethylmethane-based, fluoran-based, azaphthalide-based dyes, etc. are preferred, and specific examples thereof are shown below.

Triphenylmethane leuco dye 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide [also known as crystal violet lactone] 3-
Diethylamino-6-methyl-7-anilinofluorane 3-(N-ethyl-p-)luidino)-6-methyl-7-anilinofluorane 3-(N-ethyl-N-isoamyl)amino-6-methyl-7 -anilinofluorane 6-diethylamino-6-methyl-7-(o.

p-dimethylanilino) fluoran 3-pyrrolidino 6-methyl-7-anilinofluoran 3-piperidino 6-methyl-7-anilinofluoran 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-anilinofluorane 3-diethylamino-
7-(m-trifluoromethylanilino)fluoran 3-dibutylamino-7-(0-chloroanilino)fluoran 3-diethylamino-6-methyl-chlorofluoran 3-diethylamino-6-methyl-fluoran 3-cyclohexylamino -6-chlorofluoran 6-diethylamino-7-(0-chlorua; lino)fluoran 3-diethylamino-benzo[a]- fluoran 3-(4-diethylamino-2-ethoxypher)-
3-(1-ethyl-2-methylindol-3-yl)
-4-Azaphthalide 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-7-azaphthalide 3-(4-diethylamino-2-ethoxyphenyl)- 3-(1-octyl-2-methylindol-3-yl)-4-azaphthalide 5- (4-N-cyclohenyl-N-methylamino-2-methΦdiphenyl)-5-(1-ethyl-2- Methylindol-3-yl)-4-azaphthalide These dyes can also be used alone or in combination of two or more.

In particular, in the present invention, 3-diethylamino-6-methyl-7-anilinofluorane, 3-
(N-cyclohegysyl-N-methylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-
isoamyl)amino-6-methyl-7-anilinofluorane, 3-(4-diethylamino-2-ethoxyphenyl)-5-(1-ethyl-2-methylindole-3-
When yl)-4-azaphthalide is used alone, a thermal recording paper with extremely high dynamic color density can be obtained.

Also, when a mixture of 3-diethylamino-6-methyl-7-anilinofluorane and 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane is used as a basic dye. A thermosensitive recording paper having extremely high dynamic color density and excellent oil resistance and storage stability can be obtained.

Additionally, sensitizers (e.g. dibenzyl terephthalate, p-
Benzyl benzyloxybenzoate, di-p-tolyl carbonate, p-benzylbifere, phenyl α-naphthyl carbonate, 1,4-diethoxynaphthalene) can also be added. The colorless dye and stabilizer are atomized to a particle size of several microns or less using a grinder such as a ball mill, attritor, or sand grinder, or an appropriate emulsifier, and then mixed with a coating liquid by adding various additive materials depending on the purpose. do.

Other color developers may be used in combination as long as the effects of the present invention are not impaired. This coating liquid usually contains polyvinyl alcohol, modified polyvinyl alcohol, hydrobovine diethylcellulose, methylcellulose, and starches.

Binders such as styrene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, and styrene-butadiene copolymer, as well as inorganic materials such as kaolin, calcined kaolin, diatomaceous diatomaceous material, talc, titanium oxide, and aluminum hydroxide. or add organic fillers, but
In addition, mold release agents such as fatty acid metal salts, lubricants such as waxes, ultraviolet absorbers such as benzophenone and triazole, water resistance agents such as gliobazal, 2 dispersants, antifoaming agents, and pressure capri-preventing agents (e.g. Fatty acid amide, ethylene bisamide, Monkun wax, polyethylene wax), etc. can be used.

Organic color developer and basic colorless dye used in the present invention.

The type and amount of the stabilizer and other various components are determined according to the required performance and recording suitability, and are not particularly limited, but usually the organic color developer 4-methyl- 3 to 12 parts of sidiphenylsulfone in 4'-hydro, 3 to 12 parts of stabilizer, and 1 to 20 parts of filler are used, suitably 10 to 25 parts of binder based on the total solids.

The desired heat-sensitive recording paper can be obtained by applying a coating liquid having the above composition to paper or various films.

[Effect]

The organic color developer 4-methyl-4'-hydroxydiphenyl sulfone and the general formula (I) of the present invention shown in %
It is not certain whether the above-mentioned effect can be obtained when the stabilizer I) is used in combination with monobenzyl phthalate varnish or chill metal salt. However, phthalic acid monobenzyl ester metal salt is a metal salt that has a sterically bulky benzyl group as a hydrophobic group in its molecule, and maintains an appropriate balance between hydrophobicity and hydrophilicity. For this purpose, when heating causes a physicochemical reaction between the organic color developer 4-methyl-4'-hydroxydiphenylsulfone, the aico dye, and the phthalic acid monobenzyl ester metal salt to form a color-forming composition, , this color-forming composition is poorly soluble in oil;
It is thought that the effects of the present invention can be obtained if the ground color has a good shelf life.

(Effect of the invention) The effects of the present invention include the following points.

(1) Colored images are stable against adhesion of hair products and oils and fats.

(2) The ground color is stable even under high temperature and high humidity conditions.

(Example) The present invention will be described below with reference to Examples. Furthermore, during the explanation,
Parts indicate parts by weight.

[Example 1] Afi (dye dispersion) Solution B (developer dispersion) 5.5 parts Solution C (stabilizer dispersion) The canned liquid of the above composition was polished with an attritor to a particle size of 3 microns. crush.

Next, mix the dispersion liquid in the following ratio to make a coating liquid. Apply the above coating liquid to one side of 50 g/WX base paper so that the coating amount is about 6.0 g and 7 m, and dry these sheets. A heat-sensitive recording paper was obtained by processing with a supercalender so that the smoothness was 200 to 600 seconds.

[Comparative Example 1] A thermosensitive recording paper was prepared in the same manner as in Example 1 except that the C liquid used in Example 1 was not used.

[Comparative Examples 2 to 5] Liquid D (stabilizer dispersion) A thermosensitive recording paper was prepared in the same manner as in Example 1, except that the above-mentioned liquid D treated with an attritor was used instead of C'wL.

[Comparative Example 6] Liquid E (Developer Dispersion) A thermosensitive recording paper was prepared in the same manner as in Example 1, except that the above liquid E was used.

[Comparative Example 7] In Comparative Example 6, all thermosensitive recording paper was prepared in the same manner as in Comparative Example 6 except that liquid C was not used.

[Comparative Examples 8 to 11] Thermosensitive recording paper was prepared in the same manner as in Comparative Example 6, except that Liquid D was used instead of Liquid C.

Table 1 summarizes the results of quality tests conducted on the heat-sensitive recording papers obtained in the above Examples and Comparative Examples.

Note (1) Oil resistance: The image density was recorded using a heat-sensitive facsimile KB-4800 manufactured by Tokyo Shibaura Electric Co., Ltd. at an applied voltage of 18°03v1 pulse width 5.2 m'' seconds using a Macbeth densitometer (RD-514 amber filter). 0, drop castor oil onto the printed colored area, wipe it off gently with a filter paper after 10 seconds, leave it at room temperature for 3 days, then set the color density to Macbeth. Measured with a densitometer. Calculate the residual rate using the formula below.

Note (2) Blank paper storage stability: Measure the uncolored area using a Macbeth densitometer.

Note (3) Humidity resistance: 2 under high humidity conditions of 40℃ and 904RH
Image density after being left for 4 hours.

Note (4) Heat resistance: Image density after being left for 24 hours under high temperature drying conditions of 60°C.

Procedural amendments (0) January 14, 1985 Director General of the Patent Office Michibe Uga 1, Indication of case 1982 Patent Application No. 269542 2, Title of invention Thermal recording paper 3, Case of the person making the amendment Relationship with Patent applicant Jujo Seishi Name Jujo Paper Co., Ltd. 4, Agent 114 TR911-5106 Address 5-21-1-6 Oji, Kita-ku, Tokyo Subject of amendment Detailed description of the invention in the specification Column 7, Contents of correction ``(1) rC liquid (sensitizer dispersion)'' on page 14, line 13 of the specification is corrected to ``C liquid (stabilizer dispersion)''.

Claims (1)

[Claims] (1) In a thermal recording paper provided with a thermosensitive coloring layer containing a basic colorless dye and an organic color developer as the main components, the organic color developer is 4-methyl-4'-hydroxy represented by the following general formula (I). A heat-sensitive recording paper containing diphenyl sulfone and a phthalic acid monobenzyl ester metal salt represented by the following general formula (II) as a stabilizer in the heat-sensitive coloring layer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・( I
) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(II) (However, in general formula (II), M represents a calcium atom or a zinc atom.)