JPS63209884A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance an accelerating effect on color forming and enhance preservation stability, by incorporating dibenzylacetic acid as a color forming accelerator into a recording layer, in a thermal recording material comprising a leuco compound and an organic acid for developing a color by reacting with the leuco compound as main constituents. CONSTITUTION:When a thermal recording material comprising dibenzylacetic acid as a color forming accelerator is used, a conspicuous accelerating effect on color forming can be obtained, and characteristics free of troubles as to ground density, ground fogging after preservation, fading or the like can be obtained. The content of dibenzylacetic acid may be 1-40 wt.% based on the total content of solid components in a thermal recording layer. A leuco compound is a substance being colorless or light colored and capable of forming a color by reacting with an organic acid, and may be a derivative based on triphenylmethane, triphenylmethanephthalide, fluoran, leucoauramine, diphenylmethane or the like. The organic acid is a substance being solid at normal temperature and capable of functioning as a color developer upon making contact with the leuco compound when being melted by heating, and may be a phenolic substance, a fatty acid, an aromatic carboxylic acid or the like.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a method of dyeing a dyestuff that is mainly composed of a colorless or light-colored organic dye generally called a leuco compound and an organic acid such as a phenol compound that develops a color by reacting with the leuco compound. This invention relates to improvements in heat-sensitive recording materials.

(Prior Art) A thermosensitive recording paper containing a leuco compound and an organic acid is already known, for example, from Japanese Patent Publication No. 14039/1983. This recording paper is based on the principle that thermal energy is applied to the recording layer to soften or melt the leuco compound, organic acid, and binder, and the two coloring components are brought into contact to cause a coloring reaction. , used in fields such as facsimile. The recording characteristics of the recording paper vary depending on the use, but for example, in order to increase the recording speed, it is necessary to improve the recording apparatus and to promote the color development of the recording paper itself.

A commonly used method for promoting color development is to include a low melting point substance in the recording layer.

As low melting point substances, that is, color development accelerators or sensitizers, urea, phthalic anhydride, and acetanilide are used in Japanese Patent Publication No. 43-4160, and paraffin wax, carnauba wax, beeswax, wood wax, and Higher fatty acids and higher fatty acid esters were further developed by the Japanese Patent Publication No. 49-1774.
No. 8 uses salicylic acid, anisic acid, phthalic acid monophenyl ester, and phthalic acid monobenzyl ester, and in recent years, fatty acid amides have also been widely used as color accelerators. That is, Japanese Patent Publication No. 51-27599 describes the sensitizing effect of fatty acid amide by combining paraffin or microwax with fatty acid amide.
No. 139740 also describes the sensitizing effect of fatty acid amides such as stearic acid amide and oleic acid amide, and is well known.

(Problems to be Solved by the Invention) The present inventors confirmed the effects of these known color accelerators, and as a result of wide and deep studies in order to obtain a heat-sensitive recording material with even better color-forming properties, it was found that We have discovered a new color development accelerator that has excellent effects, and based on this knowledge, we have accomplished the present invention.

(Means for Solving the Problems) That is, the present invention uses the following chemical formula (I) as a color development accelerator in a heat-sensitive recording material mainly composed of a leuco compound and an organic acid that develops a color by reacting with the leuco compound. The present invention relates to a heat-sensitive recording material characterized by containing the following dibenzyl acetic acid in the recording layer.

When this substance is used in a heat-sensitive recording material, it not only has a remarkable effect of promoting color development, but also has no practical problems with other properties of the heat-sensitive recording material, such as background density, background fogging after storage, and discoloration. It was confirmed that it has characteristics without The purpose of the present invention can be achieved when the content of dibenzyl acetic acid is 1 to 40 weight i1'Z of the total solid content of the heat-sensitive recording layer.

Next, the substances used in the present invention will be described.

(1) Leuco compounds Colorless or light-colored substances that develop color by reacting with organic acids) Various derivatives such as sazine type, spiropyran type, indo-11 type, and indigo type can be mentioned, but are not particularly limited, but the following can be exemplified.

11 stalviolet lactone, 3-diethylamine-6-methyl-7-anilinofluorane, 3-(N-
Ethyl-P-)ruideino)-6-methyl-7-ani1
1-nofluorane, 3-diethylamino-6-methyl-7
-(ortho,barad-dimethylanilino)fluorane, 3
-pyrrolidino 6-methyl-7-anilinofluorane, 3-pipe IJ dino 6-methyl-7-anilinofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane oran, 3-diethylamino-7-(orthochloroani IJ)) fluorane, 3-diethylamino-7-(methato 1J fluoromethylanilino)fluorane, 3-diethylamino-6-methyl-chlorofluorane, 3-diethylamino- 6-Methyl-fluorane, 3-cyclohexylamino-6-chlorofluorane, 3-(N-inamyl-N
-ethylamino)-6-methyl-7-ani11nofluorane.

:2) Organic acid A substance that is solid at room temperature, melts when heated, and becomes a color developer when it comes into contact with a leuco compound, and includes various phenolic substances, fatty acids, aromatic carboxylic acids, etc. Examples include gallic acid. acids, sulfuric acid, 1-hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid.

2-Hydroxy-p-)ruylic acid, 3.5-xylenol, thymol, p-tart-butylphenol, 4
-Hydroxyphenoxide, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, α-naphthol, β-naphthol, catechol, resorcinol, hydroquinone, 4-tert-octylcatechol, 4
e 4- Sec -butylidenephenol, 2.2-
Dihydroxydiphenyl, 2,2'-methylenebis(4
-methyl-6-tert-butylphenol), 2.2
-Bis(4'-hydroxyphenyl)furopane 11J Name: Bisphenol A), 2-(4-hydroxyphenyl) -2-(2'-hydroxyphenyl)furopane, 4
．． 4-dihydroxy-3,3-diisopropyldiphenyl-2,2-7'lopane, 4,4'-isopropyl-11-denubis (2-tart-butylphenol), pyrogallol, phloroglucin, phloroglucin carboxylic acid,
p-methylphenol, p-phenylphenol, 4.
4-Cyclohexy IJ dendiphenol, 4.4-(1
-Methyl-n-hexy-11den)diphenol, 4.4
'-Dihydroxydiphenylmethyl-phenylmethane.

4.4-isopropylene + 7denedicatechol, 4.4-bendiIIdendiphenol, 4.4-isopropyritine bis(2-chlorophenol), 3-phenyltha + 7tylic acid, 3.5-tertiarybutyltha + 7tylic acid ,
Ethylene pyrovionate diphenol, methylene pyrovionate diphenol, 1-oxy-2-naphthoic acid,
Examples include gallic acid ester, salicylic acid ester, p-hydroxybenzoic acid ester, and 4-hydroxyphthalic acid ester.

(3) Binder A water-soluble binder is used to isolate and fix the coloring agent dispersed in fine particles from each other.
Examples include vinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid, casein, gelatin, starch, and derivatives thereof.

(4) Other additives The heat-sensitive recording material of the present invention may contain other additives in the heat-sensitive layer as necessary, such as inorganic or organic additives such as clay, calcium carbonate, aluminum hydroxide, talc, titanium oxide, zinc oxide, etc. Pigments, waxes, antioxidants for storage stability, ultraviolet absorbers, various fatty acid metal salts to prevent stickiness, water resistant agents to improve water resistance, phenolic resins,
It is also possible to add surfactants and the like.

Further, in combination with the color development accelerator according to the present invention, a known color development accelerator can be added and contained in the recording layer.

(5) Substrate The substrate used in the present invention is generally paper such as wood-free paper, medium-quality paper, or coated paper, but synthetic paper, plastic sheet, film laminated paper, etc. can also be used as the substrate. It can be used as

(Example) Below, the effects of the present invention will be explained in more detail with reference to Examples.

Example 1 a) Production of heat-sensitive recording material Liquids A and B having the following compositions were separately dispersed in a paint shaker (manufactured by Toyo Seiki) for 10 hours.

Solution A: (:'Dye 3-(N-cyclohexyl-N-methyl)
-Amino′-6-methyl-7-anilitous fluorane
5-tadibenzyl acetic acid
8-aluminum hydroxide 2
o Tastea II zinc phosphate 5f bo 11
Vinyl alcohol 12% liquid 35F water
529B
Liquid: Bisphenol A 15f No. 11 20F Zinc stearate
3f polyvinyl alcohol 12%m
35F water
52F Next, A liquid 125f, B liquid 12
52 and Polyviny x Furneaux/L/12% liquid 50? , water 4
0f'i, mixed, stirred, and adjusted to make a coating liquid. Next, this coating liquid was applied to the surface of 509/nl high-quality paper using a Maya bar so that the coating amount after drying was 82. It was coated and dried to give a heat-sensitive recording paper.

Example 2 Among the formulations of liquid A used in Example 1, 3 were used as leuco dyes.
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that -(N-isoamyl-N-ethyl)amino-6-methyl-7-anidiIInofluorane was used.

Comparative Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1 except for dibenzyl acetic acid in the formulation of liquid A used in Example 1.

Comparative Example 2 Example 1 except that stearamide 11 was used instead of dibenzyl acetic acid in the formulation of liquid A used in Example 1.
A thermosensitive recording paper was obtained in the same manner as above.

The heat-sensitive recording papers obtained in the above Examples and Comparative Examples were surface-treated using a test super calender so that the recording surface had a Beck smoothness of 500 seconds.

Next, regarding the thermal recording paper obtained by surface treatment, commercially available G
III 7 Axim I device FACOM FAX 6
Recording power 0.96 w/doζ at 21C (manufactured by Fujitsu ■)
Energization time: 0.45 rnsec, cycle: approximately 5 m5ec/
Printing was carried out under conditions of 1, and the image density and background density at the time of printing were measured using a Macbeth densitometer. The storage stability was the concentration after 24 hours of storage in a constant temperature room maintained at 60°C in a dry state. The results shown in the table were obtained for Examples and Comparative Examples. Table (Effects of the Invention) As described above, the heat-sensitive recording material of the present invention has an excellent effect of promoting color development, and also has excellent properties in terms of storage stability. The matter has been proven.

Claims (1)

[Scope of Claims] In a heat-sensitive recording material mainly composed of a leuco compound and an organic acid that develops a color by reacting with the leuco compound, dibenzyl acetic acid represented by the following chemical formula (I) is used as a color development accelerator in the recording layer. A heat-sensitive recording material characterized by containing: ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I)