JPS5925677B2 - heat sensitive recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material using a colorless or light-colored leuco dye and an acidic substance that causes the leuco dye to develop color when heated.

In more detail, it is a thermal recording material that improves the density of colored images and prevents adhesion (staking) with the thermal head. (Figure D) A thermal recording material that does not allow gas to adhere to the head even after long-term use and improves the running performance of the head. It is related to.

Thermosensitive recording materials usually develop color when heated.

A so-called thermosensitive coloring layer is formed on the surface of a support such as paper or plastic film, and a thermal printer with a built-in thermal head is used for heating. The thermal recording method using the above-mentioned recording materials is used to copy books, documents, etc., and is also used to record the output of computers, facsimile machines, measuring instruments, etc. The recording materials include lactone, lactam,
Alternatively, those having a heat-sensitive coloring layer containing a colorless or light-colored leuco dye having a spiropyran ring and an acidic substance, such as an organic acid or a phenolic substance, are attracting attention because they have the advantage of clear color tone and less fog. has been done.

However, such heat-sensitive recording materials have problems such as
It has the disadvantage that it easily develops color due to rubbing or pressure. The present invention significantly improves the prevention of color development caused by rubbing and pressure, and also improves the color development property, particularly in order to improve the density of colored images at low energy levels and prevent adhesion to the thermal head.In order to improve the head running performance. It has been done.

That is, the present invention provides a heat-sensitive recording material having a heat-sensitive color-forming layer containing a colorless or light-colored leuco dye and an acidic substance that develops color when heated. an alkyl group having 10 to 30 carbon atoms, (R.

represents an alkyl group having 1 to 3 carbon atoms. ) The present invention provides a heat-sensitive recording material containing an acyl compound of a higher aliphatic amine represented by: Specific examples of the higher aliphatic amines include decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, etc. having 10 to 30 carbon atoms. Preferably carbon number 16-
18. As the acylation component, acetyl, propionyl, butyryl or anhydrides thereof are used.

Next, a method for synthesizing the compound represented by the general formula will be explained using octadecyl acetamide as an example. Octadecylamine, 27 (parts by weight) was dissolved in acetic anhydride, 20.4 parts,
The mixture was heated in an oil bath for 5 hours with stirring, and after the reaction, the mixture was poured into ice water and the white precipitate was filtered. Recrystallization from glacial acetic acid yields octadecyl acetamide (acetyl, stearylamide) with M, p78-80°C. The amount of the higher amine acyl compound added in the present invention is 0.05 to 4 parts by weight per 1 part by weight of the leuco dye contained in the heat-sensitive coloring layer.
．． It is contained in the heat-sensitive coloring in a proportion of 0 parts by weight.

If the amount is less than 0.05 parts by weight, it will be difficult to obtain the effect of preventing rubbing and color development due to pressure;
If the amount is too large by weight, no further effect of preventing color development can be expected. In the present invention, conventionally known leuco dyes, acidic substances (organic acids, phenolic substances) and binders constituting the heat-sensitive coloring layer are used, examples of which are shown below.

1 Leuco dye 3.3-bis(P-dimethylaminophenyl)-phthalide, 3.3-bis(P-dimethylaminophenyl)-6
-dimethylaminophthalide (also known as crystal violet rag, ton) 3,3-bis(P-dimethylaminophenyl)-6-diethylaminophthalide, 3,3-bis(
P-dimethylaminophenyl)-6-chlorophthalide,
3. Triphenylmethane series such as 3-pis(P-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-(NN-diethylamino)-5-methyl-Jyo-iNN-dibenzyl Leuco base of fluoran dyes such as amino) fluorane, 3-dimethylamino-5,7-dimethylfluorane) 3-diethylamino-J-methylfluorane, 3-diethylamino-7,8-benzfluorane, etc. -diethylamino-6-methyl-J[chlorfluorane, 3-pyrrolidino-6-methyl-J[anilinofluorane, 2-{N-(3'-trifluoromethylphenyl)amino}-6-diethylaminofluoran orane, fluoran dyes such as 2-{3.6-bis(diethylamino)-9-(0-chloroanilino)xantylbenzoic acid lactam}, 3-(2'-hydroxy-l-dimethylaminophenyl)-3- (2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-
Hydroxy-4'-dimethylaminophenyl)-3-(
'2! -methoxy-5'-nitrophenyl)phthalide,
3-(2'-hydroxy-4/-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)
Phthalide, 3-(2!-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4-chloro-5'-methylphenyl)phthalide.

Organic acids: boric acid, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, benzoic acid, stearic acid, gallic acid, salicylic acid, 1-hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid acid, 2-hydroxy-
p-Toluic acid.

Phenolic substances 3.5-xylenol, thymol, p-Tert-butylphenol, 4-hydroxyphenol, methyl-4-hydroxybenzoate, 4
-Hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resorcinol, hydroquinone, 4
-Tert-octylcatechol, 4.4'-Sec-
Butylidenephenol, 2.2-dihydroxydiphenyl, 2.2-methylenebis(4-methyl-6-Tert)
-butylphenol), 2.2-bis(4'-hydroxyphenyl)propane, 4.4'-isopropylidene-bis(2-Tert-butylphenol), 4.4'-
Sec-butylidene diphenol, pyrogallol, phloroglucin, phloroglucin carboxylic acid.

4 Binders: Water-soluble ones, such as polyvinyl alcohol, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, etc.
Alternatively, aqueous emulsions such as polystyrene, vinyl chloride monovinyl acetate copolymer, polybutyl methacrylate, etc. can be used as the binder.

In the heat-sensitive recording material of the present invention, fine powders such as calcium carbonate, silica, alumina, magnesia, talc, barium sulfate, and aluminum stearate are added to the heat-sensitive coloring layer to improve the clarity of the colored image. Furthermore, the running properties of the thermal head can be further improved by adding a lubricant such as linseed oil, tung oil, wax, paraffin, polyethylene wax, or chlorinated paraffin.

The heat-sensitive color forming layer of the present invention may be provided on a support such as ordinary paper, plastic film, metallized paper, etc. by means of coating, pasting, etc., to form a heat-sensitive recording material.

Further, a thinner protective layer made of a colorless or colored transparent polymeric material may be provided on the heat-sensitive coloring layer. In some cases, it is also possible to use a self-supporting substance as a binder for the heat-sensitive coloring layer to provide a recording material without a support. The present invention will be explained below using examples.

Example 1 Dispersions A and B were prepared by mixing the following components for 10 hours using a ball mill.
were further mixed to prepare a thermosensitive coloring layer forming liquid.

(Components of dispersion liquid A) Apply the thermosensitive coloring layer forming liquid prepared as above to the surface of high-quality paper (509/M2) using a wire bar.
A heat-sensitive coloring layer having an adhesion amount of 6,09/Trl was formed by drying to obtain a heat-sensitive recording material of the present invention.

When the recording material thus obtained was printed at a temperature of 145° C. using a thermal printer equipped with a built-in thermal head, a clear black image was obtained.

In addition, in the above, a comparative heat-sensitive recording material obtained by the same procedure except that octadecyl acetamide was not contained, and a comparative heat-sensitive recording material obtained by the same procedure except that stearic acid amide was contained instead of octadecyl acetamide. A comparative heat-sensitive recording material was prepared by
In the same way as above, when printing was carried out at 145°C, black images were obtained in both cases, and when comparing the state of color development due to rubbing, the density of the color development at low temperatures, and the runnability with a thermal head, it was found that the recording material of the present invention I'm going to rub the lice that I caught.
That is, in the case of color development due to pressure, no color development was observed at all, whereas comparative recording material 1 showed significant color development and comparative recording material slightly color development.

In addition, regarding the color development properties at low temperatures, the recording material of the present invention can obtain a sufficient density of a colored image, whereas the comparative recording material 1 cannot obtain a sufficient color development image and suffers from poor runnability. showed inferior results. On the other hand, in the comparative recording material, 10
The color density obtained by printing at 0° C. was 0.78, whereas the color density of the recording material of the present invention was 1.0, demonstrating the superiority of the recording material of the present invention. Example 2 The following components were mixed for 10 hours using a ball mill in the same manner as in Example 1 to prepare dispersions C and D, and then dispersions C and D were further mixed to form a thermosensitive coloring layer. A liquid was prepared.

(Components of Dispersion Liquid C) Thermosensitive Coloring Layer Forming Solution Prepared as Above A thermosensitive coloring layer having a coating weight of 4.89/i was formed in the same manner as in Example 1 for the thermosensitive recording material of the present invention. I got it.

Using the thus obtained recording material, it was printed at a temperature of 100°C using a thermal printer equipped with a built-in thermal head.
When printed, a clear blue image was obtained. When tested in the same manner as in Example 1, no rubbing or pressure-induced color development was observed, and the running properties of the low-temperature color-forming thermal printing head were also good as in Example 1.

Example 3 A heat-sensitive recording material of the present invention was obtained in exactly the same manner as in Example 2 except that N-octadecylpropionamide was used instead of heptadecylacetamide.

Claims (1)

[Scope of Claims] 1. A heat-sensitive recording material having a heat-sensitive color-forming layer containing a colorless or light-colored leuco dye and an acidic substance that causes the leuco dye to develop color when heated, in which the heat-sensitive color-forming layer is represented by the following general formula: A heat-sensitive recording material characterized by containing an acyl compound of a higher aliphatic amine. General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ {In the formula, R_1 is an alkyl group with 10 to 30 carbon atoms, R_2
represents an alkyl group having 1 to 3 carbon atoms. }