JPS6261616B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel fluoran compounds, processes for their preparation and pressure-sensitive or thermal copying papers containing them as dye-forming substances. More specifically, the present invention relates to the general formula () (In the formula, R ₁ and R ₂ each represent an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a benzyl group, a phenyl group, or a methyl-substituted phenyl group, and
R ₁ and R ₂ may form a saturated ring together with N. _R3
is hydrogen, chlorine or an alkyl group having 1 to 4 carbon atoms,
n is 1 to 3, R ₄ is hydrogen or a methyl group, ring A is a benzene ring or a naphthalene ring) and a pressure-sensitive or heat-sensitive compound having the fluoran compound as an electron-donating coloring agent on a support. It is copy paper. Alternatively, the present invention can be applied to the general formula () (wherein R ₁ , R ₂ and ring A have the above meanings) and a compound represented by the general formula () (In the formula, R ₃ , n, and R ₄ have the above meanings.) Production of a fluoran compound represented by the general formula (), characterized by reacting the compound represented by the following in the presence of a dehydration condensation agent: It is the law. With the recent information age, the demand for pressure sensitive and thermal copying papers has increased. In general, pressure-sensitive copying paper is prepared by applying microcapsules of a solvent solution of an electron-donating coloring agent to one surface of the paper, and applying an acidic substance to the other surface of the paper. Then, the two sheets are stacked facing each other so that their surfaces are in contact with each other, and the coloring agent is transferred to the acidic material-coated surface using pressure from a pencil, typewriter, etc., and color is developed to obtain a copied image. A single sheet or a self-contained sheet in which a coloring agent and an acidic substance are coated on the same paper surface may also be used. Furthermore, there are various forms of thermal copying paper.
Usually, a phenol such as bisphenol A, an acidic substance such as an organic acid, and an electron-donating coloring agent are protected with a polymeric substance such as polyvinyl alcohol and coated on one sheet or two sheets. It is. Apply plasticizers and binders if necessary. When heat is applied to the thermal paper thus obtained using a heat source such as a thermal pen, thermal element, or infrared heating element, the color former and/or the acidic substance liquefies and the two react, causing the color former to develop color. An impression is obtained. The fluoran compound of the present invention is novel and colorless in itself, but develops a deep black color when it comes into contact with acidic substances, has excellent light resistance, and has high solubility in organic solvents for pressure-sensitive pure production. It is an excellent pressure-sensitive dye and also has excellent properties as a heat-sensitive dye. Specifically, the compound represented by the general formula () of the present invention is synthesized, for example, as follows. The m-aminophenol derivative () and phthalic anhydride () or naphthalene-2,3-dicarboxylic anhydride () are dehydrated and condensed to form a 2-(4-amino-2-hydroxy)benzoic acid derivative ().
or 2-(4-amino-2-hydroxy)benzoylnaphthalene-3-carboxylic acid derivative ()
Synthesize. (In the formula, R ₁ , R ₂ and Ring A have the above-mentioned meanings.) This compound () and the diphenylamine derivative () are heated at -5°C to 60°C for several hours using a dehydration condensation agent. Let it react for several tens of hours. Next, the mixture is poured into ice water, the resulting precipitate is separated, and the mixture is neutralized with an alkali to obtain a slightly colored crystalline product. Separately, this is dried and then recrystallized to obtain a fluoran compound represented by the formula () as colorless crystals. (In the formula, R ₃ , n, and R ₄ have the above-mentioned meanings.) Examples of the dehydration condensation agent used in this reaction include sulfuric acid, phosphoric acid, polyphosphoric acid, phosphorus trichloride, anhydrous zinc chloride, and boron trifluoride. Used advantageously 90-100%
concentration of sulfuric acid is used. As the recrystallization solvent, ligroin, n-hexane, toluene, monochlorobenzene, chloroform, methyl isobutyl ketone, methyl cellosolve, isobutanol, isopropanol, dioxane, ethylene glycol dimethyl ether, etc. are used. In the present invention, the compound represented by the general formula () is specifically synthesized, for example, as follows. 2-t-Butyl-5-methylphenol is nitrosated with nitrous acid to synthesize 2-t-butyl-4-nitroso-5-methylphenol (melting point 183-184°C), which is then treated with a catalyst and hydrogen. , iron and hydrochloric acid,
By performing a ring reaction with hydrosulfite, ammonium hydrosulfide, sodium hydrosulfide, etc.,
2-t-butyl-4-amino-5-methylphenol (melting point 201-202°C) is synthesized. This 2-t
-Butyl-4-amino-5-methylphenol was added to 2-t-butyl-4 using hydrogen chloride or hydrochloric acid.
-amino-5-methylphenol hydrochloride (melting point
272.5-274℃ decomposition). Next, 2 to 5 moles of aniline was added to this hydrochloride, stirred at 170 to 230°C for several hours, and then poured into dilute hydrochloric acid solution.
By filtering, washing with water and drying, the general formula (,
A compound represented by R ₄ =CH ₃ is obtained. Purify by recrystallization or vacuum distillation if necessary. Similarly, 2-t-butylphenol is nitrosated to 2-t-butyl-4-nitrosophenol, which is reduced to 2-t-butyl-4-nitrosophenol.
- Obtain aminophenol. This is converted into a hydrochloride and then condensed with aniline to obtain a compound represented by the general formula (, R ₄ =H). Next, the compounds of the present invention obtained in this manner are shown in a table. The right column of the table shows the hue of color developed when a toluene solution of the compound of the present invention is melted onto silica gel.

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【table】

【table】

[Table] Pressure-sensitive or heat-sensitive copying paper is manufactured by a conventional method using the coloring agent thus obtained. At this time, the solvent for dissolving the coloring agent is dichlorobenzene, α-(3,4-dimethylphenyl)-α-phenylethane, methylnaphthalene,
Propylnaphthalene, butylnaphthalene, benzylbenzoate, 1,4-dibenzylbenzene, etc. can be used. In addition, examples of acidic substances include clays such as acid clay, activated clay, and attabar guide, and novolac-type polymers of one or more phenols such as resorcinol, paraphenylphenol, phenol, cresol, and butylphenol. used. The present invention will be explained in more detail below using Examples. In the text, parts represent parts by weight. Example 1 (Synthesis example of color former No. 1) 25.5 g of 4-hydroxy-2-methyl-5-t-butyldiphenylamine (melting point 95-97°C) and 2-
31.3 g of (4-diethylamino-2-hydroxybenzoyl)benzoic acid are dissolved in 300 g of 95% sulfuric acid at below 5°C. Thereafter, stir and keep warm at -5 to 5°C for about 24 hours. After the reaction is complete, the reaction mixture is poured into 3 liters of ice water, stirred for about 1 hour, and then washed with water. Next, add 1 liter of 5% caustic soda to this wet cake.
Disperse, stir, filter, wash with water, and dry. Dissolve the obtained solid in 400 g of toluene and add 5 g of activated carbon.
After heating and raising the temperature, filter and purify with activated carbon. Next, this toluene solution was concentrated and toluene-
Recrystallized from hexane or dioxane to obtain 35.5 g of white crystals (melting point 195-196°C) (yield 66.6%)
Obtained. This is a dye with good light and water resistance that develops a reddish black color on silica gel. Example 2 (Synthesis example of color former No. 2) 2(4-diethylamino-
2-Hydroxybenzoyl)benzoic acid 31.3g 20
℃ or below, followed by 4-hydroxy-2,
After adding 27 g of 4'-dimethyl-5-t-butyldiphenylamine (melting point 135.5 to 137°C) at 5°C or lower, the mixture is stirred at a temperature of -5 to 5°C for about 24 hours. After the reaction was completed, the reaction mixture was poured into 3 liters of ice water and operated in the same manner as in Example 1 to obtain 48.2 g (yield: 88.3%) of white crystals with a melting point of 113-114°C. This developed a black color on silica gel. Example 3 (Synthesis example of color former No. 5) 2(4-diethylamino-
2-Hydroxybenzoyl)benzoic acid 31.3g 20
℃ or below, followed by 4-hydroxy-2,
28.4g of 2',4'-trimethyl-5-t-butyldiphenylamine (boiling point 182-185℃/1.5mmHg)
The mixture is added at a temperature below 0.degree. C., and then kept stirring at -5 to 5.degree. C. for about 24 hours. After the reaction was completed, the reaction mixture was poured into ice water in Step 3, and the melting point was determined in the same manner as in Example 1.
44g (yield 78.6%) of white crystals at 155-156°C were obtained. This developed a reddish black color on silica gel. Example 4 (Synthesis example of color former No. 11) 2-(4-diethylamino-
36.4 g of 2-hydroxybenzoyl) naphthalene-3-carboxylic acid was dissolved at below 15°C, and then 4-
Add 25.5 g of hydroxy-2methyl-5-t-butyldiphenylamine at 5°C or lower, and then
Keep stirring at ℃ for about 40 hours. After the reaction was completed, the reaction mixture was poured into ice water in Step 3, and the same procedure as in Example 1 was carried out to obtain 38.5 g of white crystals with a melting point of 161-162.5°C.
(yield 66.2%). This developed a reddish black color on silica gel. Example 5 (Synthesis example of color former No. 12) 2-(4-diethylamino-
36.4 g of 2-hydroxybenzoyl) naphthalene-3-carboxylic acid was dissolved at below 15°C, and then 4-
Add 27 g of hydroxy-2,4'-dimethyl-5-t-butyldiphenylamine at below 5°C, and then
Keep stirring at 5-5°C for about 40 hours. After the reaction was completed, the reaction mixture was poured into ice water in Step 3, and the following Example 1 was prepared.
Produce white crystals with a melting point of 141-142.5℃ using the same procedure as above.
44g (yield 73.8%) was obtained. This developed a black color on silica gel. Example 6 (Synthesis example of color former No. 14) 2-(4-diethylamino-
36.4 g of 2-hydroxybenzoyl) naphthalene-3-carboxylic acid was dissolved at below 15°C, and then 4-
Hydroxy-2,2',4'-trimethyl-5-t-
28.4 g of butyl diphenylamine is added at a temperature below 5°C, and the mixture is stirred at -5 to 5°C for about 40 hours. After the reaction was completed, the reaction mixture was poured into ice water in Step 3, and the same procedure as in Example 1 was carried out to obtain 44.8 g (yield: 73.4%) of white crystals with a melting point of 143 to 144.5°C. This developed a reddish black color on silica gel. Example 7 4-hydroxy-2,4'-dimethyl-5-t-
For 25.5 g of butyl diphenylamine, 2-(4
-dibenzylamino-2-hydroxybenzoyl)benzoic acid 43.7 g, 2-[4(N-p-tolyl-N-ethyl)amino-2-hydroxybenzoyl]benzoic acid 37.5 g, 2[4-(N-cyclohexyl) -N-ethyl)amino-2-hydroxybenzoyl]benzoic acid 36.7g or 2-[4-(N-
cyclohexyl-N-ethyl)amino-2-hydroxybenzoyl]naphthalene-3-carboxylic acid
Using 41.7g, the reaction was carried out in the same manner as in Example 1, and 52.7g each of color forming agents No. 19, No. 22, No. 28, and No. 29 was obtained.
(yield 78.5%), 50.6 g (yield 83.2%), 51.2 g (yield 85.3%), and 46.2 g (yield 70.9%) were obtained. Example 8 To 25.5 g of 4-hydroxy-4'-methyl-5-t-butyldiphenylamine, 31.3 g of 2-(4-diethylamino-2-hydroxybenzoyl)benzoic acid, 2-(4-dibenzylamino) -2-hydroxybenzoyl)benzoic acid 43.7g, 2-[4
-(N-p-tolyl-N-ethyl)amino-2
-Hydroxybenzoyl]benzoic acid 37.5 g, or 2-[4-(N-cyclohexyl-N-ethyl)
Amino-2-hydroxybenzoylbenzoic acid
Using 36.7 g, the reaction was carried out in the same manner as in Example 1, and 45.9 g each of color formers No. 36, No. 40, No. 41, and No. 43 were obtained.
(yield 86.3%), 48.9 g (yield 74.3%), 47.8 g (yield 80.4%), and 48.2 g (yield 82.3%) were obtained. Example 9 25.5 g of 4-hydroxy-4'-methyl-5-t-butyldiphenylamine, 36.4 g of 2-(4-diethylamino-2-hydroxybenzoyl)naphthalene-3-carboxylic acid, 2-[4 -(N-cyclohexyl-N-ethyl)amino-2-hydroxybenzoyl)naphthalene-3-carboxylic acid
41.7 g, or 2-[4-(N-p-toluyl-N
-ethyl)amino-2-hydroxybenzoyl]
Using 42.5 g of naphthalene-3-carboxylic acid, the reaction was carried out in the same manner as in Example 1 to produce 41 g (yield 70.5%) and 46.8 g of color former No. 37, No. 44, or No. 42, respectively.
(yield 73.6%) or 39.1 g (yield 60.6%) was obtained. Example 10 (Production of pressure-sensitive paper) Example 2 was added to 100 parts of 1,1-diphenylethane.
Three parts of the color former obtained in step 1 were dissolved at 100°C. Separately, 25 parts of Vidaskin gelatin having an isoelectric point of 8 and 25 parts of gum arabic were dissolved as encapsulating agents in 300 parts of 50°C warm water. While stirring the gelatin-gum arabic mixed solution, the coloring agent-containing oil was added and emulsified and dispersed. Add this emulsion to 1000 more
The mixture was diluted with warm water, and acetic acid was gradually added dropwise to adjust the pH of the liquid to 4 to 4.3, and the encapsulant was deposited around the oil droplets to form sol-like capsules.
The capsules were cooled to about 10° C. to gel, and then 10 parts of a 25% aqueous solution of glutaraldehyde was added to harden the capsules. Apply this capsule-containing coating solution to one side of a paper weighing 45 g/m ² in dry weight.
It was applied to a coating amount of g/m ² to form an electron-donating color forming agent coating amount. On one side of this paper, 100 parts of acid clay as an electron-receptive substance was dispersed in 200 parts of water, and styrene and
A coating solution containing 30 parts of butadiene latex (50% solids) was applied to a dry weight of 5 g/m ² , and several layers were layered with the electron-receptive substance coating layer facing each other, and the writing was applied. I pressed. A black copy image was obtained on the surface coated with the electron-receptive substance. Even when water and alcohol were attached to this image area, there was no discoloration or disappearance. Further, no discoloration or fading was observed even when exposed to direct sunlight. Example 11 In place of the coloring agent obtained in Example 2, Example 4 was used.
Alternatively, pressure-sensitive paper was obtained in the same manner as in Example 10, except that each of the color formers obtained in Example 5 was used alone. The hue of the printed images obtained on the pressure-sensitive copy paper was black in all cases, and the pressure-sensitive paper had good light resistance and water resistance. Example 12 (Production of thermal paper) 30 parts of the compound obtained in Example 2 was added to 150 parts of 10
% polyvinyl alcohol aqueous solution and 65 parts of water using a mixer (referred to as component A). 35 parts of bisphenol A, 10 parts of polyvinyl alcohol
Disperse 150 parts of % aqueous solution in 65 parts of water in the same way (referred to as component B). Mix 3 parts of component A and 67 parts of component B, and spread the sheet so that the dry weight is approximately 5 g/ ^m2 . Apply on top. The sheet thus obtained could be used alone as a thermal paper, and an excellent black image could be obtained with the thermal copying paper.

Claims (1)

[Claims] 1 General formula () (In the formula, R ₁ and R ₂ each represent an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a benzyl group, a phenyl group, or a methyl-substituted phenyl group, and
R ₁ and R ₂ may form a saturated ring together with N. _R3
is hydrogen, chlorine or an alkyl group having 1 to 4 carbon atoms,
n is 1 to 3, _R4 is hydrogen or methyl group, ring A
represents a benzene ring or a naphthalene ring). 2 General formula () (In the formula, R ₁ and R ₂ each represent an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a benzyl group, a phenyl group, or a methyl-substituted phenyl group, and
R ₁ and R ₂ may form a saturated ring together with N. Ring A represents a benzene ring or naphthalene ring) and a compound represented by the general formula () (In the formula, R ₃ is hydrogen, chlorine, or carbon number 1
-4 alkyl group, n is 1 to 3, _R4 represents hydrogen or a methyl group) is reacted in the presence of a dehydration condensation agent () (In the formula, R ₁ , R ₂ , R ₃ , n and R ₄ have the above-mentioned meanings.) A method for producing a fluoran compound represented by the following. 3 General formula () (In the formula, R ₁ and R ₂ each represent an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a benzyl group, a phenyl group, or a methyl-substituted phenyl group, and
R ₁ and R ₂ may form a saturated ring together with N. _R3
represents hydrogen, chlorine, or an alkyl group having 1 to 4 carbon atoms, n represents 1 to 3, R ₄ represents hydrogen or a methyl group, and Ring A represents a benzene ring or a naphthalene ring. ) A pressure-sensitive or heat-sensitive copying paper having a fluoran compound represented by the following as an electron-donating coloring agent on a support.