JPS58119893A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a heat-sensitive recording material having good stability for color images and free of discoloration and disappearance of color image even in contact with oil, etc. and also free of storage problems of recording images, by adding a specified bisphenol compound as a developing agent to a leuco dye. CONSTITUTION:In a heat-sensitive recording material containing a leuco dye [e.g., 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide]and a developing agent capable of coloring the leuco dye upon reaction with the dye when heated, the developing agent used is a bisphenol compound of the formula. These materials, prior to being applied on a support, are mixed with a binder (e.g., PVA), together with a fine powder (e.g., calcium carbonate or silica) as needed, and the preferred proportion of the bisphenol compound added is 2-4pts.wt. per pt.wt. leuco dye. USE:Output of CPU, printer of table calculator, etc., facsimile, automatic booking device, heat-sensitive recording type label, etc.

Description

[Detailed description of the invention] The present invention relates to a leuco-based heat-sensitive recording material.

Conventionally, leuco-based heat-sensitive recording materials are known that contain a leuco dye and a color developer that reacts with the leuco dye to develop color when heated, in a sheet-like support. However, in the case of conventional leuco-based heat-sensitive recording materials, the stability of the image after heating and color development is poor, and the color image may fade or disappear when it comes into contact with organic solvents such as oil, and the color image may fade or disappear due to fingerprints. Problems such as color fading occurred frequently. Therefore, in the case of conventional leuco-based heat-sensitive recording materials, there are problems in storing recorded images, and solving this problem has become an important technical issue.

As a result of extensive research to solve these problems, the inventors of the present invention discovered that the purpose could be achieved by using a special bisphenol compound as a color developer, and the present invention was completed. It was.

That is, according to the present invention, in a heat-sensitive recording material containing a leuco dye and a color developer that reacts with the leuco dye to develop color when heated, the bisphenol compound Wt represented by the formula is used as the color developer. 3. The color developer used in the present invention is a bisphenol compound represented by the formula d1, which is used in an amount of 1 to 6 parts by weight per 1 part by weight of the leuco dye.
It is used in parts by weight, preferably 2 to 4 parts by weight.

Moreover, this bisphenol compound does not need to be used alone, and can be used in combination with a conventional color developer.

The thermosensitive color forming layer used in the present invention contains a leuco dye, a color developing substance, a binder, etc. These components will be specifically described below.

(g) Leuco dye As the leuco dye, leuco forms of the various colorless or light-colored dyes shown below are usually used.

In particular, it is preferable to use leuco forms of triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based dyes.

393-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide 3v3-bis(p-dimethylaminophenyl)phthalide 393-bis(p-dimethylaminophenyl)-6-dimethylaminophenyl 3v3-bis(p -dimethylaminophenyl)-6-chlorophthalide 3-(N-P-)dyl-N-ethylamino)-6-methyl-7-(N-phenylamino)fluoran 3-diethylamino-7-chlorofluoranbenzoyl leucometele /Blue 6I-chloro-81-methoxy-bency/trinobilirosbilane 6I-bromo-81-methoxy-benzoindolino-pyrylospirane 2-[3 dilobis(diethylamino)-9-(0-chloroanilino)xanthyl]benzoic acid lactam.

ω) Color developer The above-mentioned bisphenol compound is used as an essential component as the color developer in the present invention, but other color developers can be used in combination. Examples of the color developing substance used in combination in this case include those shown below.

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, 2 -Hydroxy-
p-) Ruylic acid, 395-xylenol, thymol, p
-1ert-butylphenol, 4-hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resorcinol, hydroquinone, 4-1
crt-octinol, 22I-dihydroxydiphenyl, 2>2'-methylenebis(4-methyl-(i-t
ert-butylphenol), 292-bis(4-hydroxyphenyl)propane, 494-impropylidene-bis(2-tert-butylphenol), 4+4-
sec-butyritene diphenol, pyrogallol, phloroglucin, phloroglucin carboxylic acid.

(0) Binding agent 5-Thermal coloring 1-As the binding agent that is bonded and supported on the entire support, the following binders are used.

water-soluble ones such as polyvinyl alcohol, methoxy7-cellulose, hydroxy-7ethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, etc.
Alternatively, aqueous emulsions such as polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, etc. can be used as the binder.

In addition, 1. If necessary, conventional auxiliary additives such as #, calcium oxide 1, silica, alumina, magnesia, Merck, titania, barium sulfate, aluminum stearate, and other fine powders may be added to improve the clarity of the colored image. can be improved. Further, a heat sensitivity increasing agent such as a higher fatty acid amide can be included.

6- In the heat-sensitive recording material of the present invention, in order to further improve chemical resistance, a water-soluble polymer layer (barrier layer) is provided on the surface of the heat-sensitive recording layer, between the support and the heat-sensitive coloring layer, and/or on the back surface of the support. ) can be provided.

Examples of water-soluble polymers in this case include polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, starch, gelatin, methoxycellulose, and polyacrylamide.

Further, inorganic or organic fine particles can be added to this water-soluble polymer layer, and a conventional water resistance agent can also be added.

The heat-sensitive recording material of the present invention can be applied as a heat-sensitive recording sheet in the fields of computer output, printers such as calculators, medical measurement recorders, facsimiles, automatic ticket vending machines, etc. In particular, it is advantageously applied as a heat-sensitive recording label.

The heat-sensitive recording paper obtained in the above Examples and Comparative Examples was heated in a heat block at 150° C. under a pressure of 2 K17 cm and heated for 1 second to develop color.Then, the following tests were conducted using the obtained colored samples. The results are shown in Table-1.

Heat resistance test: After being left in a dry atmosphere at 60°C for 24 hours, the color density was measured using a Macbeth densitometer.

Humidity test: 2 in an atmosphere of 40℃ and 90% relative humidity.
After leaving it for 4 hours, measure the color density.

Oil resistance test: After applying cottonseed oil and leaving it in the air for 24 hours, measure the color density.

Table-1 (color density) -4shi

Claims (1)

[Claims] (1) A heat-sensitive recording material containing a leuco dye and a color developer that reacts with the leuco dye to develop color when heated, characterized in that a bisphenol compound represented by the formula is used as the color developer. Heat-sensitive recording material.