JPS6352592B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a pressure-sensitive or heat-sensitive recording paper having a support containing a fluorane derivative as an electron-donating coloring agent. More specifically, the present invention is based on the general formula () (In the formula, R ¹ and R ² represent an alkyl group having 1 to 8 carbon atoms, and R ³ represents a cycloalkyl group, a cyanoethyl group, a carboamidoethyl group, a carbalkoxyethyl group, a tetrahydrofurfuryl group, or a furfuryl group. This is a pressure-sensitive or heat-sensitive recording paper having a fluoran derivative shown in the following as an electron-donating coloring agent in the support. Pressure-sensitive recording paper and heat-sensitive recording paper, which utilize a coloring reaction caused by the contact between an almost uncolored electron-donating substance and an almost uncolored electron-accepting substance, have evolved rapidly with the development of the current information age. Demand is increasing. Generally, pressure-sensitive recording paper is produced by dissolving an electron-donating white dye (hereinafter referred to as a coloring agent) in an organic solvent.
The top paper is emulsified into a few microns and microencapsulated with a polymer compound such as gelatin, and this is coated on a support, and the other side is coated with an electron-accepting substance (hereinafter referred to as a color developer) on the support. The coated surfaces of the two are placed opposite each other, and by applying pressure such as pen pressure, the microcapsules are destroyed and the coloring agent in the capsules is released and transferred to the coloring agent surface.
This is a recording method that produces a color reaction to obtain a copied image. In addition, thermal recording paper has a color former and a color developer supported in a binder (for example, a polymeric substance such as polyvinyl alcohol) so that the two do not come into contact with each other.
The most common type is one provided on a support, and there is a recording method in which at least one of a color former or a color developer is melted by heating and brought into contact, causing a color reaction to produce a copied image. In recent years, there has been an increasing demand for color formers that can produce black images due to the need to make copies from recording paper on which images have been obtained by the color reaction between the color former and the color developer under pressure or heat as described above. It's here. In principle,
Is it possible to obtain a black image by mixing several suitable color formers of different hues?
Since the light fastness, water fastness, etc. of the image differ depending on the type of coloring agent, there have been drawbacks such as the hue changing depending on the storage condition of the recording paper. Therefore, efforts are being made to develop dyes that can produce black images using a single coloring agent.
At present, no dye has yet been found that produces a black image that is satisfactory in all respects such as hue, fastness, self-coloring property, and cost. The present inventors have discovered that the fluoran derivative represented by the general formula () itself is a white crystal with no coloration, but when it comes into contact with an acidic substance, it develops a black tone,
The present invention was completed based on the discovery that the dye has excellent light resistance, water resistance, and strong fastness and is useful as a coloring agent for pressure-sensitive or heat-sensitive recording paper. Dichlorobenzene, α-(3,4
-dimethylphenyl)-α-phenylethane, methylnaphthalene, propylnaphthalene, butylnaphthalene, benzylbenzoate, 1,4-dibenzylbenzene, etc. can be used. Encapsulation methods include a coacervation method using gelatin, a method in which a film is formed from an outer phase, and an interfacial polymerization method that utilizes a film-forming reaction between an inner phase and an outer phase. In addition, examples of acidic substances include clays such as acid clay, activated clay, and attabar guide; novolac-type polymers of one or more phenols such as resorcinol, paraphenylphenol, phenol, cresol, and butylphenol; Examples include metal salts of benzoic acid, salicylic acid, and their derivatives. The compound represented by the general formula () of the present invention is synthesized, for example, as follows. First of all, the general formula () (In the formula, R ¹ and R ² have the above meanings.) A compound represented by the general formula () (In the formula, R ³ has the above-mentioned meaning, and R represents hydrogen or an alkyl group having 1 to 4 carbon atoms.) Using a dehydration condensation agent, the phenol derivative represented by Allow to react for several hours to several tens of hours. Next, it is poured into water, and after separating the precipitate that has formed as necessary, it is treated with an alkali, and further heat-treated as necessary to obtain slightly colored white crystals. Separately, after drying,
When recrystallized, the fluoran derivative represented by the general formula () is obtained as white crystals. Another synthesis method is to use a compound represented by the general formula () and a compound represented by the general formula () (In the formula, R has the above-mentioned meaning.) The aminophenol derivative represented by the following formula is reacted using a dehydration condensation agent at about -5 to 90°C for several hours to several tens of hours. Then, inject it into water to neutralize the alkali.
By differentiating the general formula () (In the formula, R ¹ and R ² have the above-mentioned meanings.) A compound represented by the following is obtained. Next, the compound represented by the general formula () is alkylated in an organic solvent with a halide, sulfuric acid ester, ^{toluenesulfonic} acid ester, methanesulfonic acid ester, phosphoric acid ester, or acrylonitrile, acrylic acid ester, acrylamide, etc. of the group R3. By doing this, slightly colored white crystals are obtained, and by recrystallizing these, the fluoran derivative represented by the general formula () is obtained in the form of white crystals. The dehydrating agent used when synthesizing the compound of general formula () or general formula () from the compound represented by general formula () and the compound of general formula () or general formula () may include sulfuric acid, phosphoric acid, polyester, etc. Phosphoric acid and the like can be used, but advantageously 85% to 100% strength sulfuric acid is used. Further, as the recrystallization solvent, n-hexane, toluene, monochlorobenzene, chloroform, methyl isobutyl ketone, methyl cellosolve, isobutanol, isopropanol, dioxane, ethylene glycol dimethyl ether, etc. are used. Pressure-sensitive or heat-sensitive recording paper is produced by a conventional method using one or more of the color formers thus obtained, or in combination with other color formers. The fluoran derivative represented by the general formula () used in the method of the present invention is a compound that is not specifically described in the literature, and exhibits a deep black color when developed by the color developer. Recording paper obtained using this color former is particularly excellent in storage stability, color development, light fastness, and water resistance. In other words, pressure-sensitive paper or thermal paper using this coloring agent is different from pressure-sensitive paper or thermal paper using a known black coloring compound (). When compared with pressure-sensitive paper, capsule-coated paper has less discoloration due to light and colored images have excellent light fastness, while thermal paper has less discoloration due to temperature and humidity of uncolored paper, and the coloring of colored images has less discoloration due to temperature and humidity. It has the great advantage of being less susceptible to discoloration due to humidity and discoloration due to light. Furthermore, when applied to multicolor thermosensitive recording paper, the color development when heated is clear, multicolor development occurs without color mixing, and it is stable in storage. Next, some examples of the fluoran compounds of the general formula () used in the present invention are shown in a table. Note that the hue indicates the color developed on a thin layer of silica gel.

【table】

[Table] Next, the present invention will be specifically explained with reference to Examples.
In the examples, parts represent parts by weight. Example 1 Fluoran compound 2.0 shown by the above structural formula
part was dissolved in 100 parts of α-(3,4-dimethylphenyl)-α-phenylethane, and 20 parts of gum arabic,
Add a solution of 160 parts of water and emulsify. 20 parts of acid-treated gelatin and 160 parts of water were added thereto, acetic acid was added under constant stirring to adjust the pH to 5, and 50 parts of water was added to proceed with coacervation. After further adding acetic acid to adjust the pH to 4.4, 4 parts of 37% formalin are added to form a dura mater. The above operations are performed at 50°C. Next, this system is 10
The mixture was cooled to 0.degree. C. to promote gelation of the thick liquid film to increase the hardening effect, and after adjusting the pH to 9 by adding an aqueous solution of caustic soda, it was left to stand for several hours to form a capsule emulsion.
Next, 30 parts of fine cellulose powder and 100 parts of an aqueous solution of oxidized starch dissolved at a concentration of 10% are mixed with this capsule emulsion, and the mixture is applied to paper and dried to produce a top paper. When this top sheet was layered with the bottom sheet and pressure from a pen or typewriter was applied, a black color developed. In other words, when using paper whose surface is coated with a polymer of paraphenylphenol,
In either case, clear black characters appeared when using a base paper whose surface was coated with acid-treated activated clay. The above-mentioned pressure-sensitive paper had a good shelf life and a fast color development speed, and the colored characters could withstand long-term exposure and did not fade even when wet with water. Example 2 A pressure-sensitive recording paper was prepared in the same manner as in Example 1 using the fluoran compound represented by the above structural formula. When printing pressure was applied to this pressure-sensitive paper, it developed a black color. This pressure-sensitive paper had good storage stability, fast color development speed, and excellent light fastness and water resistance of colored characters. Example 3 30 parts of the fluoran compound represented by the above structural formula was mixed with 150 parts of a 1.0% polyvinyl alcohol aqueous solution.
Disperse using a sand mill in 65 parts of water (referred to as component A). Disperse 35 parts of bisphenol A and 150 parts of a 10% aqueous solution of polyvinyl alcohol in 65 parts of water (referred to as component B). 33 1 part of component A and 67 parts of component B are mixed and coated on the sheet to a dry weight of about 5 g/m ² . The sheet thus obtained could be used alone as a thermal paper, and an excellent black image could be obtained with a thermal copying machine. The above-mentioned thermal paper was a beautiful paper with no self-coloring property, the coloring speed was fast, and the light resistance and water resistance of the colored characters were excellent. Example 4 A thermal paper was produced in the same manner as in Example 3 using the fluoran compound represented by the above structural formula. This thermal paper had no self-coloring property, the coloring speed was fast, and the colored characters had excellent light fastness and water resistance. Example 5 A thermal paper was produced in the same manner as in Example 3 using the fluoran compound having the above structure. This thermal paper had similar properties to the thermal paper of Example 3.

Claims (1)

[Claims] 1 General formula () (In the formula, R ¹ and R ² represent an alkyl group having 1 to 8 carbon atoms, and R ³ represents a cycloalkyl group, a cyanoethyl group, a carboamidoethyl group, a carbalkoxyethyl group, a tetrahydrofurfuryl group, or a furfuryl group. .) A pressure-sensitive or heat-sensitive recording paper having a fluoran derivative represented by the following formula as an electron-donating coloring agent in a support.