JPS5926476B2 - heat sensitive recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, and more specifically, a color-forming substance,
The present invention relates to a heat-sensitive recording material in which a heat-sensitive layer contains a phenolic substance or organic acid that reacts with the phenolic substance or organic acid to develop color, and a specific pigment.

Recently, with social demands such as an increase in the amount of information, resource saving, labor saving, and pollution-free living, various recording methods have been put to practical use and improved in the field of information recording.

Among them, the thermal recording method is: (i) primary coloring, so no developing process is required; (li) equipment is easy to assemble and maintain; qiD
Thermal recording sheets (thermal recording materials) have the characteristics of having a feel similar to that of plain paper and being relatively inexpensive.For this reason, they are used for computer output, fax machines, various measuring instruments, printers such as calculators, and medical equipment. It has been put to practical use in measuring instrument recorders, etc. Generally used heat-sensitive recording materials consist mainly of a color-forming substance (usually a colorless or light-colored color-forming substance) on a support, and a phenolic substance or organic acid that causes this color-forming substance to develop color when heated. A heat-sensitive layer is formed.

In such recording materials, it is known to add a white inorganic pigment to the heat-sensitive layer in order to improve the whiteness of the heat-sensitive layer and to enable writing on the heat-sensitive layer with a pen. However, when a thermal head is run on a heat-sensitive layer containing a white inorganic pigment, the gas from the heat-sensitive layer material may fuse to the thermal head, worsening recording characteristics, or causing severe wear of the thermal head. This has the disadvantage that it becomes difficult to record for a long time. The present inventors have been conducting research and examination on heat-sensitive recording materials for some time, and have found that the above-mentioned disadvantages can be effectively solved by adding a combination of certain pigments to the heat-sensitive layer. I found it.

The present invention has been completed based on this. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat-sensitive recording material in which wear of the thermal head is significantly reduced, gas from the heat-sensitive layer material does not adhere to the thermal head, and furthermore, writing is possible with a pen.

Another object of the present invention is to provide a heat-sensitive recording material that provides high recording density and provides clear images even during high-speed recording. That is, the present invention provides a heat-sensitive layer in which a color-forming substance and a phenolic substance or an organic acid that reacts with the color-forming substance to form a color are dispersed in a binder. This is a heat-sensitive recording material characterized in that it is added in an amount of ~3 parts by weight.

In the present invention, kaolin is used as an inorganic filler in the heat-sensitive layer.
Light calcium carbonate is used.

The lightweight calcium carbonate referred to here is made by burning limestone (heavy calcium carbonate) to make quicklime, emulsifying it in water, settling it, drying it, and then classifying it. The appropriate amount of these inorganic fillers (kaolin powder and light calcium carbonate) to be added to the heat-sensitive layer is 1 to 4 parts by weight per 1 part by weight of the color-forming substance.

If the amount is less than 1 part by weight, the heat-sensitive layer material may fuse to the head, resulting in poor writability and a decrease in whiteness.

On the other hand, if the amount exceeds 4 parts by weight, the image density tends to decrease. In addition, light calcium carbonate and kaolin are used together, but the ratio (weight) of the former to the latter is 1.
: 1 to 3 is desirable.

If the amount of kaolin is less than 1 part by weight relative to 1 part by weight of calcium carbonate, head wear will be significant.If Vl exceeds 3 parts by weight, gas from the heat-sensitive layer material will fuse to the head. The color-forming substances used in the present invention include triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based,
Leuco derivatives such as spiropyrans, which are usually colorless or slightly pale in color. Specifically, for example, crystal violet lactone, malachite green lactone, 3,3
-bis(p-dimethylphenyl)-6-aminophthalide, 3,3-bis(p-dimethylaminophenyl)-6-
dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)-6-P-toluenesulfonamide,
3,3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3-dimethylamino-6-methoxyfluoran, 3-diethylamino-J[chlorofluoran,
3-diethylamino-6-methyl-J[chlorofluorane, 3-dibutylamino-6-methyl-J[chlorofluoran], 3-dimethylamino-6-methyl-J[phenylaminofluorane, 3-dimethylaminofluorane] Minnow J me[methyl-(N-methyl-p-toluidino)7 fluorane, 3-diethylamino J me[benzylaminofluorane, 2-{
N-(3'-trifluoromethylphenyl)amino}-
6-diethylaminofluorane, benzoylleucomethylene fluorine, 3-methyldi-β-naphthospiropyran, penso β-naphthospiropyran, d-chloro-8'
-Methoxybenzoindolinopyrillospiran, 6L
Bromo-8'-methoxybenzoindolinopyrillospiran, 2-[3,6-bis(diethylamino)-9-
Examples include (0-chloroanilino)xanthyl]benzoic acid lactam, but are not limited to these. Examples of the phenolic substances or organic acids that cause these color-forming substances to develop color when heated include d-naphthol, β-naphthol, 4-t-octylphenol, 4-phenylphenol, 4-t-butylphenol, 4-hydroxy Phenoxide, 4-hydroxyacetophenone, resorcinol, hydroxynon, pyrogallol, phloroglucin, phloroglucin carboxylic acid, 4-l-Sec-butylidene diphenol, 2,2-bis(p-hydroxyphenyl)propane, 2,2-bis(p-hydroxyphenyl)butane, 4,4'-cyclohexylidene diphenol, 2,2-pis(2,5-dibromo-4-hydroxyphenyl)proban, 4,1-isopropylidene Bis(2-t-butylphenol), 2,2-methylenebis(4-chlorophenol), 4-t-octylcatechol, 2,cudihydroxydiphenyl, 2,Z-methylenebis(4-methyl-6-t- butylphenol), 2
, Z-bis(4-oxyphenyl)propane, 3,5-
Examples include, but are not limited to, xylenol.

Further, as the binder, for example, polyvinyl alcohol, gelatin, gum arabic, starch, hydroxyethyl cellulose, methyl cellulose, polyacrylamide, polyacrylic acid, carboxymethyl cellulose, methoxy cellulose, etc. are used.

However, the heat-sensitive recording material according to the present invention has a heat-sensitive layer in which these color-forming substances, phenolic substances, organic acids, and inorganic fillers are dispersed in a binder on a support (paper, synthetic paper, synthetic resin film, etc.). It was formed in

When the heat-sensitive layer contains 1 to 4 parts by weight of wax per 1 part by weight of the color-forming substance, the adhesion of the heat-sensitive layer material to the head and the abrasion of the thermal pen or thermal head are further improved. become.

Waxes used here include vegetable waxes, mineral waxes (carnauba wax, montan wax, or modified products thereof, etc.), higher fatty acid amides, condensates of higher fatty acid amides and formaldehyde, Waxes such as condensates of higher fatty acids and ethylenediamine, such as stearamide, lauric acid amide,
Palmitic acid amide, oleic acid amide, condensate of stearic acid amide and formaldehyde, (methylene bis stearamide C, 2H35CONHCH2NHCOC
17 Condensation of χ stearamide and formaldehyde 2 products (methylolated stearamide C, 7H35C
ONHCH2OH] Condensation product of palmitic acid amide and formaldehyde (methylene bispalmitamide Cl, H
3lCONHCH2NHCOCl5H3l, methylolated palmitamide C,,H3lCONHCH2OH),
Stear > Condensate of phosphoric acid and ethylene diamine (ethylene bis stearamide Cl7H35CONHCH2C
O
However, if petroleum-based waxes such as polyethylene, polypropylene, or paraffin wax are used, they tend to stick to the head very easily, and therefore gases tend to adhere to them, which is not preferable. In order to actually make this heat-sensitive recording material, three color-forming substances, a phenolic substance or organic acid (color developer), kaolin, and light calcium carbonate (inorganic filler) must be used alone or in combination except for the color-forming substances. ,
This is mixed with a protective colloid as a binder, a surfactant, a wetting agent, an antifoaming agent, etc. if necessary, and dispersed using a dispersing machine such as a ball mill, atto lighter, or sand mill, and then this dispersion is placed on a support. What is necessary is just to apply|coat and dry so that a solid content may become 4-10 fd. In this case, as mentioned above, it is desirable to use kaolin in the form of a hexagonal thin plate, so it is advantageous to use kaolin containing kaolinite.

Alternatively, kaolin (in particular halloysite) can be made into a sheet by known means such as denemination. As described above, the heat-sensitive recording material of the present invention contains kaolin and light calcium carbonate in combination in the heat-sensitive layer. Although no detailed study has been made as to why this achieves the desired purpose, it is probably because the heat-sensitive layer surface has less irregularities and a lower coefficient of friction due to the use of such an inorganic filler. This is thought to be due to the synergistic effects of kaolin and light calcium carbonate. Next, examples will be shown.

Example 1 The following solutions [A], [B] and [C] were separately ground and dispersed in a ball mill for 24 hours, and filtered through a 200 mesh.

In addition, the following liquids [D] and [E] were pulverized and dispersed using separate attritors for 10 hours, and filtered through a 200-mesh filter.

In order to improve coating properties, this was mixed at a liquid temperature of 25°C.
Then, the solution was diluted with water and adjusted to 300 cps using a B-type viscometer to prepare a heat-sensitive layer forming solution.

Next, this heat-sensitive layer forming liquid was applied to commercially available high-quality paper (approximately 55 tons/
M2) was coated with a wire bar so that the dry coating amount was 5 to 61 cm2, and dried to produce a heat-sensitive recording material.

This heat-sensitive recording material is subjected to a calendering process to achieve a surface smoothness of 200 to 300 seconds, and then the quality is checked using a recorder equipped with a stick pen as a heat head (manufactured by Watanabe Sokki Co., Ltd.). Examined.

The results are shown in Table-1. In abrasion tests, using light calcium instead of calcium carbonate has less head wear, and because there is less gas adhesion, there is no line blur or distortion in the image, and there are no thick or thin lines, which is good for head matching. It was confirmed that

On the other hand, when a serial thermal head with a 5x7 dot matrix was made and an image test was performed, clear images were obtained.

Comparative Example 1 A heat-sensitive recording material was prepared in the same manner as in Example 1 using the following formulation.

As shown in Table 1, the evaluation of this heat-sensitive recording material (comparative product 1) was not good.

Comparative Example 2 A thermosensitive recording material was prepared in the same manner as in Example 1 using the following formulation.

The evaluation of this heat-sensitive recording material (comparative product 2) was not good, as shown in Table 1.

Comparative Example 3 (Talc 150V) 150y of a 5% methyl cellulose aqueous solution and 200V of water were pulverized and dispersed in a ball mill for 24 hours to prepare liquid [G].

Subsequently, a heat-sensitive recording material was prepared in the same manner as in Example 1 using the following formulation.

In this heat-sensitive recording material (comparative product 3), there was a significant amount of head wear, and the heat head did not operate smoothly, making it impossible to draw an image.

Comparative Example 4 A heat-sensitive recording material was prepared in the same manner as in Example 1 using the following formulation.

The evaluation of this heat-sensitive recording material (Comparative Example 4) is shown in Table 1, and was consistently good.

Comparative Example 5 [B] Thermal recording was carried out in the same manner as in Example 1 except that heavy calcium carbonate (Whiten P-10, manufactured by Toyo Fine Chemical Co., Ltd.) was used in place of light calcium carbonate in the liquid composition. I made the materials.

The evaluation of this heat-sensitive recording material (comparative product 5) was as shown in Table 1, and was not good. Note 1) Note 2) In the abrasion test, after scanning an aluminum pen for 360 m at 10 mm/sec, the length of the pen at its deepest point (reduction in wear) was measured using an optical microscope.
was measured.

Are ◎, @, △, Δ, and × from good to bad? It shows the stage of change.

Claims (1)

[Scope of Claims] 1. A heat-sensitive layer containing a color-forming substance and a phenolic substance or an organic acid that reacts with the color-forming substance and dispersed in a binder, containing 1 part by weight of light calcium carbonate and 1 to 10% of kaolin. A heat-sensitive recording material characterized in that the additive is added in an amount of 3 parts by weight. 2. The recording material according to claim 1, wherein the total amount of light calcium carbonate and kaolin is 1 to 4 parts by weight per 1 part by weight of the color-forming substance. 3. The recording material according to claim 1, wherein the heat-sensitive layer further contains a wax substance. 4. The recording material according to claim 3, wherein the content of the wax substance is 1 to 4 parts by weight per 1 part by weight of the color-forming substance.