JPS582835B2 - Thermal paper that prevents debris from adhering to the thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a color-forming lactone compound, which is usually colorless or pale-colored, and a color-forming lactone compound, which is usually colorless or light-colored, and a color-forming lactone compound, which is usually colorless or pale-colored, in order to reduce the amount of residue deposited on the thermal head of thermal facsimiles, thermal printers, etc. A thermal paper made of a phenolic substance that develops color when heated and a water-soluble polymer adhesive, which is characterized by containing both higher fatty acid amides and light calcium carbonate with an average particle size of 0.2 to 5 microns. This paper relates to high-sensitivity thermal paper.

It has been known for a long time that color-forming lactone compounds such as crystal violet lactone react with phenols to produce colors, and the application of this reaction to thermal paper was described, for example, in Japanese Patent Publication No. 14039/1983. This is publicly known.

The high-sensitivity thermal paper of the present invention needs to have color development sensitivity as high as possible in order to reduce power consumption and increase printing speed in thermal facsimiles, thermal printers, etc. that actually use thermal paper. Higher fatty acid amides are added as essential ingredients to prevent color development due to scratches.

However, when using a material with a low melting point such as higher fatty acid amide, when printing with a thermal facsimile or thermal printer, especially when printing for a long time, the molten material becomes scum on the thermal head compared to the material that is not used. There is a strong desire to improve the adhesion of thermosensitive paper, since it greatly deteriorates the printing quality. However, for the performance reasons mentioned above, it is impossible not to add higher fatty acid amides.

As a result of various studies, the present inventors determined that the average particle diameter was 0. 2～
It has been found that the adhesion of residue to the thermal head can be surprisingly prevented only by adding 5 μm of light calcium carbonate to the heat-sensitive coating layer in an amount of 50 to 500% by weight based on the fatty acid amide.

It is generally known that fillers such as talc, clay, and starch are added to the heating element to prevent the molten material from sticking to the heating element, but talc, clay, starch, etc. In a system consisting of a color-forming lactone compound, a phenol substance that causes the color-forming lactone compound to develop color when heated, a water-soluble polymer adhesive, and a higher fatty acid amide, it is better than not including it, but its effect is truly insufficient.

Furthermore, one of the present inventors proposed in Japanese Patent Application Laid-open No. 49-90142 to incorporate calcium carbonate or magnesium carbonate to improve thermal stability, but the purpose is completely different from that of the present invention. In addition, in the present invention, it is only light calcium carbonate with an average particle size of 0.2 to 5μ that exhibits a particularly remarkable effect, and magnesium carbonate, heavy calcium carbonate, and light calcium carbonate with a particle size of less than 0.2μ. However, the effect is extremely insufficient.

On the other hand, if light calcium carbonate larger than 5 μm is used, the coated surface will be rough and the color development sensitivity will be poor, resulting in a loss of commercial value, so it is generally not used for paper coating and is also unsuitable for the present invention.

Also, what has a remarkable effect in the present invention is a highly sensitive thermal paper made of a colorless color-forming lactone compound, a phenolic substance that causes the color-forming lactone compound to develop color when heated, a water-soluble polymer adhesive, and higher fatty acid amites. system, and the effect is not remarkable in systems without higher fatty acid amides.

Typical examples of colorless or light-colored color-forming lactone compounds used in the present invention are as follows, but are not limited thereto.

Crystal violet lactone, malachite green lactone, 3,3-bis(paradimethylaminophenyl)-4,5,6,7-tetrachlorphthalide.

3-ethylamino-6-chlorofluorane.

3-Cyclo 3-pendylamino-6-chlorofluorane.

Hexylamino-6-chlorofluorane.

3-morpholino 5,6-penzofluorane.

3-diethylamine-6-methyl-7-chlorofluorane.

3-diethylamine-7-chlorofluorane.

3-diethylamino-6,7-dimethylaminofluorane.

3-diethylamine-7,8-penzofluorane.

3-diethylamino-7-methoxyfluorane.

3-diethylamine-7-dibenzylaminofluorane.

3-diethylamine-7-anilinofluorane.

3-diethylamino-5-b-benzo-7-pendylaminofluorane.

3-Diellylamino-6-methyl-7-anilinofluorane.

3-diethylamino-7-dibenzylamino-3',4
',5',6'-tetrachlorofluorane.

3-Ethyltolylamino-6-methyl-7-anilinofluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane.

3-Piperidino-6-methyl-7-anilinofluorane.

3-diethylamino-7-(N-methyl-N-(3'-
}Lifluoromethylphenyl)amino}fluorane.

3-diethylamine-7-(N-3'-}lifluoromethylphenyl)aminofluorane.

The phenolic compound used in the present invention is 4,4'-inpropylidenediphenol, which has the property of liquefying or vaporizing at 70° C. or higher and reacting with the color-forming lactone compound to develop color.

4,4'-isopropyritenebis(2-chlorophenol).

4,4'-isopropylidene bis(2-tertiarybutylphenol).

4.4'-sec-butylidene diphenol.

4,4'-cyclohexylidene diphenol.

Bisphenol sulfone. 4,4'-thiobis(4-tert-butyl-3-methylphenol).

2,2'-bis-(4-hydroxyphenyl)-n-hebutane.

Novolac type phenolic resin.

Suitable examples include phenolic substances having two or more hydroxyl groups in one molecule, such as halogenated novolak type phenolic resins.

Higher fatty acid amides that can be used as essential additives include behenic acid amide, oxystearic acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, methylolated fatty acid amide, ethylenebis fatty acid amide, methylenebis fatty acid amide, and higher fatty acids. There are reactants with ethanolamine, etc., and these are used alone or in combination of two or more.

In the present invention, normally colorless or light-colored color-forming lactone compounds, phenolic substances, and higher fatty acid amides are crushed into particles as small as possible by a grinder such as a ball mill using a water-soluble polymer adhesive or a surfactant. It is preferable to grind until the following particles are obtained.

Preferably, light calcium carbonate having an average particle diameter of 0.2 to 5 μm is sufficiently dispersed using a dispersant.

If the particles are rough, the coated surface of the thermal paper will be rough, resulting in a decrease in color development and a decrease in high quality.

Other whitening agents and fillers such as Merck and clay starch may also be added.

It is also possible to add waxes such as paraffin and polyethylene to the coating liquid in order to greatly reduce and prevent colored stains caused by scratching, friction, and pressure.

Generally, thermofusible adhesives cannot be used because they may stick to the heating element; starch polyvinyl alcohol, carboxymethyl cellulose, methyl vinyl ether-maleic acid copolymer, styrene-maleic acid copolymer, hydroxy Water-soluble polymer adhesives such as ethylcellulose, casein, gelatin, and gum arabic are used.

The support used in the present invention is generally paper, but synthetic resin films, woven fabric sheets, etc. can also be used.

When coating, use a coater head such as an air knife, rubber doctor, steel plate, roll, extrusion, etc., and dry at a relatively low temperature.

Since the surface condition is generally not good just by coating, it is common to treat the surface with a calender or the like to improve the smoothness of the coated surface.

Next, examples will be described to further specifically explain the present invention.

In the examples, parts refer to parts by weight. Example 1 Stir thoroughly with a stirrer to disperse.

A heat-sensitive coating liquid was prepared by mixing them in a ratio of A:B:C:D=1:5:3:5.

This heat-sensitive coating liquid was applied to a base paper having a basis weight of 45 g/m 2 using an air knife coater so that the coated amount after drying was about 5 g/m 2 and dried at a temperature not exceeding 60°C.

It was finished with a super calendar to give a smoothness of 200 to 300 seconds, and was further slit to a width of 180 mm using a slitter to create a roll of 100 m in length.

The winding was carried out using a Toshiba thermal FAX KB-500 using the standard chart shop 2 of the Institute of Image Electronics Engineers of Japan at a main scanning speed of 5001 pm.
When the thermal head was observed after printing for 100 m at a recording voltage of 20 V, the adhesion of debris was very small, with a width of about 0.5 to 1 mm.

Example 2 A test was carried out in the same manner as in Example 1 except that 3-piperidino-6-methyl-7-anilinofluorane was used instead of crystal violet lactone, and as a result, very little residue was attached to the head.

Example 3 Table 1 shows the results of using various organic and inorganic powders in place of the white glossy PC in Example 2.

As is clear from Table 1, the average particle size is 0.2 to 5μ.
It can be seen that only light calcium carbonate has a remarkable effect on preventing residue from adhering to the head.

In Table 1, the column "Dess adhesion" is the result of visual judgment of the state of adhesion of adhesion to the thermal head, where ○ means there is almost no adhesion of adhesion and is good for practical use, and × means there is a lot of adhesion of adhesion and it is practically impossible. shows.

Example 4 In Example 1, thermal papers of Examples and Comparative Examples were prepared using calcium carbonate shown in Table 2 instead of the white glossy PC.

This thermal paper is a highly sensitive thermal paper.

Separately, in Example 1, a thermal paper was prepared as a comparative example in which Liquid C was not added, that is, fatty acid amide S was not used, and calcium carbonate shown in Table 2 was used instead of Shirogane PC.

This thermal paper is not a highly sensitive thermal paper. The printing density in Table 2 was measured using a Macbeth densitometer after printing in the same manner as the measurement of the amount of deposited residue.

Surface smoothness was determined visually.

In Table 2, light refers to light calcium carbonate, C
The presence or absence of liquid refers to the presence or absence of addition of liquid C in Example 1, that is, the presence or absence of fatty acid amide S. Therefore, presence means that fatty acid amide S was added, and absence means that fatty acid amide S was added.
"Heavy" means not adding , "heavy" means heavy calcium carbonate, "high-sensitivity type" means high-sensitivity thermal paper, and "non-high-sensitivity type" means not high-sensitivity thermal paper.

Table 2 shows that high-sensitivity thermal paper using higher fatty acid amides has improved printing density, that is, color development sensitivity, compared to thermal paper that does not use higher fatty acid amide, and its use is especially essential for high-speed printing thermal paper. However, it is clear that the amount of deposits increases significantly with its use, and that there is a technical problem to be solved.

However, such technical problems do not exist in thermal paper that does not use the higher fatty acid Amai.

Furthermore, in high-sensitivity thermal paper using higher fatty acid amides, in a system that uses light calcium carbonate (
If the average particle size of light calcium carbonate is less than 0.2 μm, no effect can be expected; if it is larger than 5 μm, the surface smoothness will be poor, the coated surface will be rough, and the color development sensitivity will be poor. (the example is 1.0, but 0
．． It gets worse at 8.

), it is also clear that the commercial value will be lost. Furthermore, it is clear that even when heavy calcium carbonate is used instead of light calcium carbonate, there is no effect of reducing the amount of deposited scum.

Claims (1)

[Claims] 1. Colorless or slightly pale color-forming lactone compound,
A thermal paper made of a water-soluble polymer adhesive and a phenolic substance that causes a color-forming lactone compound to develop color when heated, containing both higher fatty acid amides and light calcium carbonate with an average particle size of 0.2 to 5 microns. Highly sensitive thermal paper that prevents residue from adhering to the thermal head.