JPH0452232B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure-sensitive recording material using a fluorane derivative that develops a black color.

Conventionally, coloring reactions between colorless or light-colored basic dyes and organic or inorganic electron-accepting substances have been used.
Various methods have been proposed for recording information transmitted through energy media such as pressure, heat, and electricity; for example, Kondo, Iwasaki, Paper and Paper Technology Association Journal.
Pressure-sensitive copying sheets, heat-sensitive recording sheets, electrically conductive heat-sensitive recording sheets, ultrasonic recording sheets, electron beam recording sheets, electrostatic recording sheets as described in Vol. 30, pp. 411-421, 463-470 (1976) A large number of methods have been proposed for application to photosensitive recording sheets, photosensitive printing materials, type ribbons, ballpoint pen inks, crayons, stamp inks, etc.

Electron-donating color-forming substance (hereinafter simply referred to as color-forming agent)
and electron-accepting color developer (hereinafter simply referred to as color developer)
In these pressure-sensitive recording materials that utilize color reactions with color formers, colored images exhibiting various hues can be formed by selecting the type of color former. For the purpose of obtaining further copies from an image, there is a strong demand for a recording medium capable of producing a black colored image. In this case, in principle, a black colored image can be obtained by mixing coloring agents that develop different hues such as red, blue, yellow, and green, but the coloring speed and light intensity depend on the type of coloring agent. Since the fastness to temperature and humidity differs, there is a drawback that the initially colored image cannot maintain its color tone. Therefore, research has been carried out to obtain black colored images using a single coloring agent, but it has not been possible to satisfy all of the requirements such as the stability of the coloring agent before coloring, coloring speed, coloring density, fastness, hue, and cost. A capable black color former has not yet been found, and as a result, black color recording materials have not always been satisfactory.

However, the fluoran derivatives of the present invention represented by the following general formula [] [In the formula, R represents a propyl group or a butyl group. ]
is a colorless or light-colored stable compound that develops a red-black, green-black, or high-density black hue when it comes into contact with a color developer, and recorded images obtained using this substance retain their initial color tone over a long period of time. It has properties that can be stably maintained, and when applied to pressure-sensitive recording paper, a recorded image with particularly excellent initial color development can be obtained.

Among them, the recorded image obtained using the fluoran derivative represented by the following general formula [] exhibits a desirable recorded color tone of red and black, and has the property of stably maintaining the initial color tone even when exposed to sunlight. It is something that

[In the formula, R has the above-mentioned meaning. ] Compounds having a similar structure to the fluoran derivatives represented by the general formula [] are
No. 17490, Special Publication No. 51-15445, Special Publication No. 56-52759
The fluoran compound described in the above issue is known as a chromogen in pressure-sensitive copying paper and heat-sensitive recording paper, but the fluoran derivative represented by the general formula It is excellent in that the color density produced by close contact is high.

The fluoran derivative of the present invention having the excellent properties described above can be produced by the following typical method. That is, as shown below, first, an m-substituted aminophenol derivative [] and a phthalic anhydride derivative [] are reacted to synthesize a 2-(2-hydroxy-4-substituted amino)benzoylbenzoic acid derivative [], and then, This and 4-hydroxy-
A fluoran derivative represented by the general formula [] can be produced by condensing a diphenylamine derivative [].

[In the formula, R ₁ represents a hydrogen atom or a C ₁ to C ₄ alkyl group, and R has the above-mentioned meaning. ] In addition, in the above reaction, when R ₁ of the 4-hydroxy-diphenylamine derivative is a C ₁ to C ₄ alkyl group, a triarylmethane derivative represented by the following general formula [ ] which is a precursor of the desired fluoran derivative may be synthesized.

[In the formula, R and R ₁ have the above-mentioned meanings. ] In this case, the obtained triarylmethane derivative is filtered if necessary, and the pH of the system is adjusted to 9 with an alkaline substance such as sodium hydroxide or potassium hydroxide.
By doing the above and heating to 50 to 100°C, the desired fluoran derivative can be obtained.
In addition, acetone, benzene,
The yield can be effectively increased by using an organic solvent such as toluene or xylene in combination.

As the color developer used in the pressure-sensitive recording medium of the present invention, a substance that acts as a Brönsted or Lewis acid is preferably used. Specifically, for example, inorganic color developers such as acid clay, activated clay, attapulgide, bentonite, colloidal silica, aluminum silicate, magnesium silicate, zinc silicate, tin silicate, calcined kaolin, and talc, oxalic acid, maleic acid, tartaric acid, and citric acid. acids, aliphatic carboxylic acids such as succinic acid and stearic acid, benzoic acid, paratertiary butylbenzoic acid, phthalic acid, gallic acid,
Salicylic acid, 3-isopropylsalicylic acid, 3-
Phenylsalicylic acid, 3-silcohexylsalicylic acid, 3,5-di-tertiarybutylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 3-
Phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3,5-di-(α-methylbenzyl)
Salicylic acid, 2-hydroxy-1-benzyl-3
- Aromatic carboxylic acids such as naphthoic acid, 4-tert
-octylphenol, 4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,
4'-isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis(6-tert-3-methylphenol), 4,4' −
Dihydroxydiphenylsulfon, hydroquinone monobenzyl ether, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2',4,4'- Tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, 4-
Methyl hydroxybenzoate, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate,
sec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, tolyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, 4-hydroxybenzoic acid Phenolic compounds such as phenylpropyl, phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-methoxybenzyl 4-hydroxybenzoate, para-phenylphenol-formalin resin, para-
Organic color developers such as phenolic resins such as butylphenol-acetylene resins, and combinations of these organic color developers such as zinc magnesium, aluminum, etc.
Examples include salts with polyvalent metals such as calcium, titanium, manganese, tin, and nickel.

Regarding pressure-sensitive recording media, for example, U.S. Patent No.
No. 2505470, No. 2505471, No. 2505489, No. 2505470, No. 2505471, No. 2505489, No.
No. 2548366, No. 2712507, No. 2730456, No. 2712507, No. 2730456, No.
No. 2730457, No. 3418250, No. 3924027, No.
As described in No. 4010038, there are various types of pressure-sensitive recording bodies, and the pressure-sensitive recording body of the present invention includes these various types of pressure-sensitive recording bodies. In general, the fluoran derivatives of the present invention are used alone or in combination, and if necessary, alkylated naphthalenes, alkylated naphthalenes, and alkylated A dispersion in which synthetic oils such as diphenyl, alkylated diphenylmethane, and alkylated terphenyl, vegetable oils such as cotton oil and castor oil, animal oils, mineral oils, or mixtures thereof are dissolved in a solvent and dispersed in a binder. liquid or the above solution by coacervation method, interfacial polymerization method,
The pressure-sensitive material of the present invention can be prepared by applying the dispersion liquid, which is contained in microcapsules by various capsule manufacturing methods such as the in situ method and dispersed in a binder, onto a support such as paper, plastic sheet, or resin-coated paper. A recording body is manufactured. Of course, the so-called upper sheet, which is coated with the above-mentioned dispersion liquid on one side of the support,
A so-called intermediate sheet is prepared by coating one side of a support with a color developer coating liquid containing a color developer as a main component and the above dispersion liquid applied on the other side, and furthermore, the above capsules and color developer are coated on the same side of the support. There are various forms such as so-called stand-alone copying sheets in which the capsules and the color developer are coexisted on the same surface by applying a mixed coating liquid or by applying a developer coating liquid on top of the capsule dispersion liquid. As mentioned above, is included. The amount of fluorane derivative used varies depending on various conditions such as the desired coating amount, the form of the pressure-sensitive recording medium, the capsule manufacturing method, the composition of the coating liquid including various auxiliaries, and the coating method. You can select it as appropriate. In any case, by using the fluoran derivative represented by the general formula [] of the present invention as a basic dye in various conventional pressure-sensitive recording materials, a pressure-sensitive recording material capable of forming recorded images with excellent color development properties. is obtained.

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited thereto unless it goes beyond the gist of the present invention. Further, parts and % in the examples represent parts by weight and % by weight, respectively, unless otherwise specified.

Synthesis Example 1 36.9 g of 2-(2-hydroxy-4-N,N-dibutylamino)benzoylbenzoic acid and 2,2',
3'-trimethyl-4-methoxybiphenylamine
26.5g was reacted in 100ml of concentrated sulfuric acid at room temperature for 24 hours. The obtained reaction product was poured into 1000 ml of ice water, and the formed precipitate was collected by filtration. After dispersing this in 500ml of water, add sodium hydroxide aqueous solution to make the pH 11.
After that, 300 ml of toluene was added and heated at 85°C for 3 hours. Next, the toluene layer was separated, toluene was distilled off under reduced pressure, and recrystallized from propyl alcohol to obtain colorless 3-N,N-dibutylamino-6-methyl-7-(2,3-xylidino)fluoran. 45.7 g of needle crystals were obtained. In addition, the yield was 81.6
%, mp 163-164°C, developed black on silica gel.

Synthesis Example 2 36.9 g of 2-(2-hydroxy-4-N,N-dibutylamino)benzoylbenzoic acid and 2,2',
25.0 g of 4'-trimethyl-4-hydroxy-biphenylamine was reacted in 100 ml of concentrated sulfuric acid at room temperature for 17 hours. The obtained reaction product was poured into 1000 ml of ice water, and the pH was adjusted to 9 by adding a 20% aqueous sodium hydroxide solution at room temperature, and the resulting precipitate was filtered, washed with water, and dried. The product was then recrystallized from propyl alcohol to obtain 36.9 g of 3-N,N-dibutylamino-6-methyl-7-(2,4-xylidino)fluoran as colorless crystals. In addition, the yield was 65.9
%, mp 160-161°C, developed black on silica gel.

Synthesis Example 3 36.9 g of 2-(2-hydroxy-4-N,N-dibutylamino)benzoylbenzoic acid and 2,2',
26.5 g of 5'-trimethyl-4-ethoxy-biphenylamine was reacted in 100 ml of concentrated sulfuric acid at room temperature for 24 hours. The obtained reaction product was poured into 1000 ml of ice water, and the resulting precipitate was collected by filtration. After dispersing this in 500ml of water, add sodium hydroxide aqueous solution to make the pH 11.
After adding 300 ml of acetone, the mixture was refluxed for 3 hours.
Next, acetone was removed, and the resulting crystalline precipitate was filtered, washed with water, and further recrystallized from ethyl alcohol to give 3-N,N-dibutylamino-6-methyl-7-(2,5-xylidino). ) 48.0 g of fluoran was obtained as colorless needle crystals. In addition, the yield was 85.7%,
mp 136-137°C, developed black color on silica gel.

Synthesis Example 4 2-(2-
3-N,N-dipropylamino-
42.2 g of 6-methyl-7-(2,3-xylidino)fluorane was obtained as colorless crystals. Yield 79.3%,
mp158-159°C (chloroform-ethanol recrystallization) Developed a black color on silica gel.

Example 1 5 parts of the fluorane derivative obtained in Synthesis Example 1 were dissolved in 100 parts of isopropylated naphthalene, and 25 parts of pigskin gelatin with an isoelectric point of 8 and 25 parts of gum arabic were dissolved in 350 parts of hot water (50°C). was added to emulsify and disperse. To this emulsion, 1000 parts of warm water was added, the pH was adjusted to 4 with acetic acid, the emulsion was cooled to 10°C, and 10 parts of a 25% aqueous solution of glutaraldehyde was added to harden the capsules. This capsule-containing coating liquid was applied to one side of a 45 g/m ² base paper so that the dry weight was 5 g/m ² , and on the other side, 3,5-di-(α-methylbenzyl)salicylic acid was applied to 200 parts of water. 20 parts zinc salt, 80 parts kaolin
A developer coating liquid containing 30 parts of styrene-butadiene copolymer emulsion (50% solids) dispersed therein was applied to a dry weight of 5 g/m ² to form pressure-sensitive recording paper (inside paper). Obtained.

When several sheets were stacked and pressed so that the capsule-coated surface and the developer-coated surface faced each other, a black colored image was obtained on the developer-coated surface. This colored image had a faster color development rate than the initial stage of color development, a higher density than the initial stage of printing, and no discoloration or browning was observed even when exposed to sunlight.

Claims (1)

[Scope of Claims] 1. A pressure-sensitive recording material containing at least one fluoran derivative represented by the following general formula [] as an electron-donating color-forming substance. [In the formula, R represents a propyl group or a butyl group. ]