JP2562886B2 - Recording material - Google Patents

Description

The present invention relates to a recording material such as a pressure-sensitive copying paper, a heat-sensitive recording paper, and an electric heat-sensitive recording paper. More specifically, the general formula (1) [In the formula, R ¹ represents a methyl group or an ethyl group, and R ² represents a pentyl group, a methoxypropyl group, or an ethoxypropyl group. Hereinafter, the same symbols have the same meaning. ] The present invention relates to a recording material using a fluorane compound represented by

The fluoran compound represented by the general formula (1) is a novel compound synthesized by the present inventors for the first time. It is almost colorless and extremely stable in the atmosphere, and has sublimability and spontaneous color development (background fog). It does not exist and is very well soluble in organic solvents. The color developer rapidly develops a dark green color, and the color image has excellent light resistance and moisture resistance. Therefore, it is an extremely valuable novel compound which can be used as a color former for black color, green color or bluish black color recording material, which has been rapidly increasing in demand in recent years.

Examples of the recording material include pressure-sensitive copying paper, heat-sensitive recording paper, electrically-conductive heat-sensitive recording paper, color-developing thermal transfer recording paper, and temperature indicating material.

"Prior Art" and "Problems to be Solved by the Present Invention" Conventionally, the following compounds (A), (B), and (C) have been put to practical use as fluoran compounds that develop a greenish color.

However, (A) has poor light fastness of the color image, (B) has poor light fastness and light resistance of the background of the color image, and (C) has low color density and poor light fastness of the background. However, the actual situation is that a satisfactory green coloring agent has not been obtained yet. The present invention has been achieved as a result of intensive studies to improve these drawbacks.

"Means for Solving Problems" and "Action" That is, the present invention is a compound in which an anilino group is introduced at the 2-position of a fluoran bone nucleus and a pentyl group, a methoxypropyl group or an ethoxypropyl group is introduced at the 6-position amino group. Unexpectedly originated from the finding that the light fastness and background light fastness of an image were improved, and further arrived at as a result of further investigation. A color forming recording material containing the compound of the general formula (1) as a color forming agent. Is provided.

In order to clarify these excellent properties, comparative test results of the compounds (D) to (F) of the present invention and the known compounds (A) to (C) are shown.

Comparative test 1-Comparison of image light fastness-Compounds (A) to (F) (5 parts each) were dissolved in 95 parts of KMC-113 (solvent for pressure-sensitive copying paper manufactured by Kureha Chemical Co., Ltd.), and Example 1 described later was performed. The above operation was performed to obtain a pressure sensitive copy paper.

These were superposed on a lower paper coated with phenol formalin resin and pressed by a roller to develop a color. The color image was exposed to sunlight and the image density was measured with a Macbeth reflection densitometer. (Using Ratten # 25 filter) The results were as follows.

Comparative Test 2-Comparison of Background Lightfastness-Compounds (A) to (F) were used as color formers and operated in the same manner as in Example 2 described later to prepare a thermosensitive recording paper. These thermal recording papers were exposed to sunlight, and the degree of red discoloration of the background was measured using the Macbeth reflection densitometer as in Comparative Test 1. (Using Ratten # 58 filter) The results were as follows.

From the above test, it was confirmed that the color former used in the present invention is totally excellent in light resistance.

Next, a method for synthesizing the fluoran compound used in the present invention will be described.

First, a meta-aminophenol derivative (2) is reacted with phthalic anhydride to synthesize a 2- (4-amino-2-hydroxy) benzoylbenzoic acid derivative (3).

Next, the 2- (4-amino-2-hydroxy) benzoylbenzoic acid derivative (3) and the general formula (4) (In the formula, R represents a hydrogen atom or an alkyl group.) The diphenylamine derivative represented by the formula (1) is condensed with a dehydrating condensing agent such as sulfuric acid, polyphosphoric acid, zinc chloride or acetic anhydride to give a compound represented by the general formula (1 ) The fluoran compound represented by the formula (1) is obtained as an almost colorless solid.

Next, the synthesis method will be specifically described with reference to synthesis examples of the compound of the general formula (1).

Synthesis Example 1 Synthesis of 2-anilino-6- (N-ethyl-N-iso-pentylamino) fluorane 2- (2-hydroxy-4-ethyl-) in 98% sulfuric acid 50 ml.
iso-pentylamino) benzoylbenzoic acid 17.8 g and 4-
12.0 g of methoxydiphenylamine was dissolved at room temperature and then stirred at 20 to 25 ° C for 48 hours. The reaction product was poured into 500 g of ice water, and the precipitated solid substance was collected by filtration.

150 ml of toluene and 70 ml of a 20% aqueous sodium hydroxide solution were added to the obtained cake, and the mixture was stirred at 85 ° C. for 2 hours. Next, the toluene layer was separated, activated carbon was added, the mixture was filtered at 80 ° C., and the filtrate was cooled. The precipitated crystals were filtered and dried to obtain 21.4 g of a light pink target compound (the following formula). mp170-171 ° C This product rapidly develops a dark green color due to active whiteness,
The λ _{max in} methanol / stannic chloride is 443 and 604 mn.

Synthesis Examples 2 to 6 Using various benzoylbenzoic acid derivatives, Synthesis Example 1
The compounds shown in the following table were synthesized by reacting in the same manner as in. All of them are almost colorless compounds, and develop a dark green color depending on the active whiteness.

In producing pressure-sensitive copying paper, thermal recording paper, etc. using these fluoran compounds, these dyes may be used alone or in combination of two or more kinds. By mixing them, the color developability and the storage stability of the image are improved. Further, in order to improve the coloring hue, the coloring density, and the stability of the image, it is possible to use together a known coloring agent that develops various known hues within a range that does not impair the performance of the compound of the present invention.

For example, 3,3-bis (aminophenyl) -6-aminophthalide, 3,3-bis (indolyl) phthalide, 3-aminofluorane, aminobenzofluorane, 2,6-diaminofluorane, 2,6-diamino -3-methylfluorane, spiropyran, phenoxazine, phenothiazine,
It is used in combination with a derivative of a compound having a basic skeleton such as leuco auramine, carbazolyl methane, 3-indolyl-3- (aminophenyl) phthalide, and 3-indolyl-3- (aminophenyl) azaphthalide.

When manufacturing pressure-sensitive copying paper, various solvents such as alkylbenzene meter, alkylbiphenyl type, alkylnaphthalene type, diallylethane type, hydrogenated terphenyl type, and chlorinated paraffin type are used alone or mixed as a solvent for dissolving the color former. It can be used, and a coacervation method, an interfacial polymerization method, or an in-situ method can be adopted for encapsulation.

As the developer, bentonite, activated clay, clay such as acid clay, salicylic acid, salicylic acid ester, metal salt of salicylic acid, 2,2-bis (p-hydroxyphenyl)
Propane (bisphenol A), hydroxy compounds such as p-hydroxybenzoic acid ester, p-phenylphenol formalin resin, p-octylphenol formalin resin and metal salts thereof are used.

Further, in manufacturing the thermal recording paper, polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, as a binder,
Gum arabic, gelatin, casein, den powder, polyvinylpyrrolidone, styrene-maleic anhydride copolymer and the like can be used, and as a developer, 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenyl ether, 4-Hydroxybenzoic acid methyl ester, 4-Hydroxybenzoic acid benzyl ester, 2,2
-Bis (hydroxyphenyl) propane, 4,4'-thiodiphenol, bis- (4-hydroxy-3-methylphenyl) sulfide, 4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone , 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone, 4,4'-dihydroxy-3,3'-
Diallyldiphenylsulfone, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, 1,7-di (4
Hydroxy such as -hydroxyphenylthio) -3,5-dioxaheptane, 1,8-di (4-hydroxyphenylthio) -3,6-dioxaoctane and bis (4-hydroxy-3-methylphenyl) sulfide The compounds can be used alone or as a mixture.

Acetanilide, paraffin wax,
Carnauba wax, higher fatty acid, higher fatty acid ester, higher fatty acid amide, phthalate ester, terephthalate ester, benzyl 4-benzyloxybenzoate, naphthol benzyl ether, 1,4-dialkoxynaphthalene,
1,5-dialkoxynaphthalene, m-terphenyl, p
-Benzylbiphenyl, dibenzylbenzene, 1-hydroxy-2-naphthoic acid ester, 2-hydroxy-3
-Naphthoic acid ester, 1-phenoxy-2-naphthoxy (1) ethylene, 1,2-di (3-methylphenoxy)
Ethylene, 1- (2-isopropylphenoxy) -2-
Naphthoxy (2) ethylene, 4,4'-dialkoxydiphenyl sulfone, benzamide, diphenylamine, benzenesulfonamide, benzenesulfonanilide, carbazole and hydroquinone dibenzyl ether can be used alone or in combination.

In addition, addition of various antioxidants, deterioration inhibitors, ultraviolet absorbers or the like or overcoating of polymer substances or the like is effective for improving the light resistance of images and the storage stability.

A known method may be used to produce a pressure-sensitive copying paper using the fluoran compound of the general formula (1). For example, the coacervation method described in U.S. Pat. Nos. 2,800,458 and 2,806,457 can be employed. In order to manufacture the heat-sensitive recording paper, for example, a known method described in JP-B-45-14039 may be adopted.

"Example" Next, a method for producing the recording paper of the present invention using the compound obtained in the above-mentioned synthesis example will be specifically described as an example.
(Hereinafter, "parts" means "parts by weight.") Example 1-Production example of pressure-sensitive copying paper-2-anilino-6- (N-ethyl-N-iso-pentylamino) fluorane (Synthesis example 1) 5 parts KMC-113 (Kureha Chemical Industry Co., Ltd. alkyl naphthalene-based solvent for pressure-sensitive copying paper) 95 parts The above mixture was dissolved by heating, and 24 parts of gelatin and 24 parts of gum arabic were dissolved in 100 parts of water. A solution having a pH adjusted to 7 was added and emulsified with a homogenizer. Add warm water to this emulsion
After adding 100 parts and stirring at 50 ° C. for 30 minutes, about 1 part of a 10% aqueous sodium hydroxide solution was added, and the mixture was further stirred at 50 ° C. for 30 minutes. Then, dilute acetic acid was gradually added to adjust the pH to 4.5, and the mixture was stirred at 50 ° C for about 1 hour, cooled to 0 to 5 ° C, and further stirred for 30 minutes.
Next, 35 parts of a 4% glutaraldehyde aqueous solution was gradually added to cure the capsule, and then the pH was adjusted to 6 with a dilute caustic soda aqueous solution and stirred at room temperature for several hours to complete encapsulation. No coloring phenomenon occurred during this operation.

The capsule liquid was uniformly coated on paper with a wire bar so that the coating weight after drying was 6 g / m ^2, and dried to obtain capsule coated paper (upper paper).

When this paper was overlaid on a paper (lower paper) coated with phenol formalin resin as a color developer, writing with a ballpoint pen revealed dark green characters on the lower paper.

This image was excellent in light resistance and moisture resistance. In addition, the capsule surface of the upper paper also showed excellent light resistance, and there was no decrease in coloring or coloring ability due to sunlight irradiation.

Example 2-Production Example of Thermosensitive Recording Paper-1) Preparation of Coloring Agent Dispersion Liquid (A) 2-anilino-6- (N-ethyl-N-ethoxypropylamino) fluorane (Synthesis Example 2) 5 parts Kaolin 15 parts 10% aqueous solution of polyvinyl alcohol 100 parts water 85 parts The above mixture was pulverized with a paint shaker (manufactured by Toyo Seiki Co., Ltd.) until the average particle size of the color former became 2 microns.

2) Preparation of color developer and sensitizer dispersion (B) Bisphenol A 15 parts Zinc stearate 10 parts Stearic acid amide 15 parts 10% polyvinyl alcohol aqueous solution 150 parts The above mixture is made into an average particle size of 3 microns with a paint shaker. Crushed until

3) Preparation and coating of heat-sensitive coating solution 10 parts of solution A and 6.5 parts of solution B were mixed and stirred to obtain a heat-sensitive coating solution. 8 g of this coating solution after drying on paper with a wire bar
/ m ² and then dried to obtain a thermosensitive recording paper.

This thermal recording paper is almost colorless without background fog,
Immediately developed a dark green color when printed with a thermal head. This color image was excellent in light resistance and moisture resistance. or,
The coated surface was also excellent in light resistance, and no coloration or deterioration in color-forming ability was caused by irradiation with sunlight.

Example 3-Production Example of Black Color Thermosensitive Recording Paper-2-anilino-6- (N-ethyl-N-) as a color former
Ethoxypropylamino) fluoran 2 instead of 5 parts
-Anilino-6- (N-ethyl-N-methoxypropylamino) fluorane 4 parts and 8-diethylamino-benzo [a] fluorane 1 part as bisphenol as a developer
The same procedure as in Example 2 was repeated except that 15 parts of 4,4'-dihydroxydiphenyl sulfone was used instead of A5 part and 15 parts of p-benzylbiphenyl was used instead of 15 parts of stearamide as a sensitizer. A thermosensitive recording paper was obtained.

This thermal recording paper is almost colorless without background fog,
By printing with the thermal head, the color quickly became dark black. This color image was excellent in light resistance and moisture resistance. or,
The coated surface was also excellent in light resistance, and no coloration or deterioration in color-forming ability was caused by irradiation with sunlight.

"Effects of the Invention" The recording material of the present invention uses the compound of the general formula (1) alone as a color-forming agent, not only when used as a dark green recording material, but also in combination with other known color-forming agents. Even when used as a black-colored recording material, it is superior in light resistance to a color-developed image and background as compared with the case where a conventional green-coloring agent is used, and has high industrial utility value.

Claims (1)

(57) [Claims] 1. A recording material containing a fluorane compound represented by the following general formula (1) as a color former. [In the formula, R ¹ represents a methyl group or an ethyl group, and R ² represents a pentyl group, a methoxypropyl group, or an ethoxypropyl group. ]