JP2000072974A - Preparation of aniline black - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pigment which is prepd. without using a harmful chromium salt or copper salt and hence does not contain chromium or copper by using hydrogen peroxide and a metal or metal salt which can be a catalyst for decomposing hydrogen peroxide and by subjecting aniline to oxidative polycondensation by using OH radicals generated as an oxidizing agent to give an oxidative condensate of aniline. SOLUTION: An acidic aq. soln. with 3-10 wt.% concn. of an aniline salt made water-soluble with an inorg. acid (e.g. hydrochloric or sulfuric acid) or an org. acid is prepd. A metal or metal salt in an amt. of at least 0.01 equivalent (based on hydrogen peroxide) is added to the soln., and then an aq. hyrogen peroxide soln. with a concn. of 10-60 wt.% and in an amt. of 0.6 equivalent (based on aniline) is added dropwise under stirring over a time of 0.5-4 hr. The aniline soln. is then stirred at 10-60 deg.C for 0.5-7 hr to subject aniline to oxidative polycondensation while using OH radicals generated as an oxidizing agent, giving aniline black of the formula (wherein n is 1-3). Iron, ferrous or ferric chloride, ferrous or ferric nitrate, ferrous or ferric sulfate, silver nitrate, etc., can be used as the metal or metal compd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing aniline black which is useful in paints for painting, poster colors, coloring materials for resin kneading and other coloring fields.

[0002]

2. Description of the Related Art Conventionally used aniline black is obtained by oxidatively condensing aniline using a copper salt as a catalyst and a chromium salt as an oxidizing agent in an acidic aqueous solution of an aniline salt rendered water-soluble by an acid. I have. Therefore, chromium and copper used as an oxidizing agent and a catalyst are contained in a large amount in the product. Further, a large amount of chromium ions and copper ions are contained in the waste liquid in the production process.

[0003]

As the jet-black pigment having a matte property, aniline black is the best, but still,
Aniline black, which contains a large amount of chromium and copper, which are harmful to the environment and the body, is being used. In addition, a large amount of labor is required for removing chromium ions and copper ions contained in the waste liquid in the manufacturing process. Therefore, there is a need for a method of producing aniline black that can be produced without using chromium salts and copper salts that are harmful to the environment and the body and that does not contain chromium or copper in the product.

[0004]

The invention according to claim 1 is
An aniline is oxidized and polycondensed by using hydrogen peroxide and a metal or a metal salt which can be a catalyst for decomposing hydrogen peroxide, and using an OH radical (.OH) generated as an oxidizing agent, thereby producing aniline which is an oxidized condensate of aniline. It is characterized by obtaining black. The invention according to claim 2 is claim 1
In the described invention, iron or an iron salt is used as a catalyst for decomposing hydrogen peroxide. According to the production method of the invention according to claim 1, a metal or a metal salt that can be a catalyst for decomposing hydrogen peroxide is used alone or as a mixture,
Hydrogen peroxide is added thereto to generate OH radicals, and the generated OH radicals act on aniline as an oxidizing agent, whereby aniline is oxidatively condensed to obtain aniline black. The structural formula of the obtained aniliblack is considered to be Chemical formula 1.

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[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of the production method, a uniform acidic aqueous solution of an aniline salt made water-soluble with an inorganic acid such as hydrochloric acid or sulfuric acid or an organic acid is prepared. The aniline content in this aqueous solution is 3 to 10% by weight, and the acids used are used alone or as a mixture. A metal or metal salt that can serve as a catalyst for decomposing hydrogen peroxide is added to the acidic aqueous solution of the aniline salt to form a homogeneous solution. While stirring the acidic aqueous solution containing the aniline salt and the metal salt, an aqueous solution of hydrogen peroxide is added dropwise over a period of time. Stirring is continued for a certain period of time after the completion of the dropwise addition of hydrogen peroxide to terminate the oxidative condensation reaction. The aqueous solution containing aniline black which has thus completed the oxidative condensation reaction is filtered, washed with water by a usual method, and further redispersed in water, adjusted to pH 5 to 8 with a commonly used alkali agent, filtered, After washing with water, drying is performed to obtain the object of the present invention. As a metal or a metal salt that can be a catalyst for decomposing hydrogen peroxide, iron, ferric chloride, ferric nitrate, ferric sulfate,
Ferrous chloride, ferrous nitrate, ferrous sulfate, platinum chloride gold, silver nitrate and the like, and used alone or as a mixture, the amount used is, for example, 0.01 equivalent or more with respect to hydrogen peroxide, Preferably, it is 0.02 equivalent or more. The oxidative condensation reaction temperature is 10 to 60 ° C., and it is not always necessary to keep it constant during this time. The concentration of the aqueous hydrogen peroxide solution is, for example, 10 to 60% by weight, and the amount used is preferably 0.6 equivalent or more with respect to aniline. The dropping time of the aqueous hydrogen peroxide solution is 30 minutes to 4 hours. The reaction stirring time after the completion of the dropping of hydrogen peroxide is 30 minutes to 7 hours.

[0006]

EXAMPLE 1 3.0 g of 62% sulfuric acid, 5.3 g of 35% hydrochloric acid and 50 ml of water
Then, after dissolving 5.0 g of aniline under stirring and dissolving, 2.2 g of ferrous sulfate dissolved in 10 ml of water is added.
While stirring and mixing at a liquid temperature of 15 ° C., 15.0 g of hydrogen peroxide having an effective concentration of 30% by weight was added over 4 hours, and then the mixture was stirred and mixed at a liquid temperature of 15 ° C. for 4 hours to complete the reaction. After completion of the reaction, the reaction solution is filtered and washed with water to obtain a paste-like black crystal. The paste-like black crystals were redispersed in 160 ml of water, neutralized to pH 7.0 with 10% sodium hydroxide solution, and after the pH was stabilized, filtered and washed with water, and the paste was dried at 60 ° C. to obtain 4.6 g of aniline black. Get.

Example 2 In 6.2 g of 62% sulfuric acid and 65 ml of water, 5.0 g of aniline was added.
And stirred and dissolved, and then 3.6 g of a 40% ferric chloride solution is added.
Is added to 15 ml of water. While stirring and mixing at a liquid temperature of 10 ° C., 15.0 g of hydrogen peroxide having an effective concentration of 30% by weight was added over 4 hours while maintaining the reaction liquid temperature at 10 ° C., and then stirred and mixed at 10 ° C. for 7 hours. To complete the reaction. After completion of the reaction, the reaction solution is filtered under reduced pressure and washed with water to obtain a paste-like black crystal. 160 m of this pasty black crystal
l of water and re-dispersed with 10% sodium hydroxide
Neutralized to 6.5, and after PH was stabilized, it was filtered under reduced pressure and washed with water.
Drying at 0 ° C. gives 4.3 g of aniline black.

Example 3 Into 6.5 g of 35% hydrochloric acid and 80 g of water were added 5.0 g of aniline, and the mixture was dissolved by stirring. Then, a solution prepared by dissolving 1.0 g of ferrous sulfate in 10 ml of water was added. While stirring and mixing at a liquid temperature of 15 ° C., 13 g of hydrogen peroxide having an effective concentration of 35% by weight was started to be dropped, and the reaction liquid temperature was gradually raised during a period of 4 hours, and the liquid temperature at the end of the dropping Is controlled to 50 ° C. Thereafter, the liquid temperature was kept at 50 ° C., and the mixture was stirred for 1.5 hours to complete the reaction. Subsequent operations were learned from Example 1.
4.9 g of aniline black are obtained.

Example 4 5.0 g of aniline in 6.5 g of 35% hydrochloric acid and 100 ml of water
After stirring and dissolving, 2.0 g of ferrous chloride dissolved in 10 ml of water is added. While stirring and mixing at a liquid temperature of 25 ° C., 15 g of hydrogen peroxide having an effective concentration of 35% is added dropwise over 3 hours. Thereafter, the reaction temperature was set to 40 ° C., and stirring was continued for 2.5 hours to complete the reaction. Subsequent operations were learned from Example 1.
4.9 g of aniline black are obtained.

[0010]

According to the present invention, aniline black, a matt black pigment which does not contain chromium or copper which is harmful to the environment or the body, can be obtained as compared with the conventionally known methods. In addition, since chromium salts and copper salts are not used during production, the health and safety aspects of workers are also improved. Further, regarding the treatment of waste liquid in the manufacturing process, there is no need to consider chromium and copper released to the environment, and thus the method is greatly simplified.

Claims (2)

[Claims] An aniline is subjected to oxidative polycondensation by using hydrogen peroxide and a metal or a metal salt which can serve as a catalyst for decomposing hydrogen peroxide, using an OH radical generated as an oxidizing agent to obtain an oxidized condensate of aniline. Characteristic method for producing aniline black. 2. The method for producing aniline black according to claim 1, wherein iron or an iron salt is used as a catalyst for decomposing hydrogen peroxide.