Method for preparing CI pigment red 57:1

Abstract

The invention discloses a method for preparing CI pigment red 57:1. The method comprises the steps as follows: 2-isonaphthol and a sodium hydroxide solution have a carboxylation reaction with carbon dioxide after directly salified and dehydrated; a product is neutralized and subjected to filter pressing to obtain a monosodium salt solution of 2-hydroxyl-3-naphthoic acid; the solution directly has a coupling reaction with diazonium salt of 4-toluidine-3-sulfoacid after purified by a resin absorption column; and a product is subjected to color lake by an inorganic calcium compound to obtain the CI pigment red 57:1 finally. According to the method, the step of purification by the resin absorption column is added, and the steps that in the prior art, 2, 3-acid powder is obtained by droppwise adding sulfuric acid to a monosodium salt solution of 2, 3-acid, drying and packaging are performed, then the sodium hydroxide solution is added to obtain the monosodium salt solution of 2, 3-acid again and the like are omitted; therefore, the problems that the use amount of sulfuric acid and the sodium hydroxide solution is large, 2, 3-acid powder requires to be dried and packaged and the like in a conventional preparation process are solved, the emission of inorganic salt to the environment is reduced, energy consumption and manpower cost are reduced, and wastewater emission load is obviously reduced.

Description

technical field [0001] The invention relates to a manufacturing method of CI Pigment Red 57:1. Background technique [0002] At present, the manufacturing method of CI Pigment Red 57:1 is obtained by coupling 2,3-acid monosodium salt with 4B acid diazonium salt, and then using calcium ions for color lake, usually adding rosin soap for modification , to improve the dispersibility of the pigment; and the 2,3-acid monosodium salt is formed by adding 2,3-acid powder and adding sodium hydroxide dropwise. [0003] The above-mentioned 2,3-acid powder in the pigment industry is manufactured as follows: add 2-naphthol to the salt-forming reactor, and then add sodium hydroxide with a concentration of 28-32% in a molar ratio of 1-1.2:1 solution, heated to 115-155°C and reacted under stirring conditions, vacuum dehydration after the reaction, to obtain dry 2-naphthol sodium salt; transfer 2-naphthol sodium salt to a high-pressure reactor, and heat to 230-260°C , feed carbon dioxide un...

AI Technical Summary

Problems solved by technology

In this repeated process, the cost of sulfuric acid and sodium hydroxide, the discharge of saline wastewater, the cost of centrifugal filtration, drying, and packaging all increase the manufacturing cost of CI Pigment Red 57:1, increasing industrial water consumption and environmental protection. Pollution

At the same time, considering that 2,3-acid has been identified as a mutagenic chemical substance that has carcinogenic effects on the human body, and during the transportation, storage, and use of solid materials due to packaging damage, exposure, and volatilization, etc., It is easy to cause pollution to the surrounding environment, especially the feeding step during use, which is easy to spread in the air due to dust, which brings health hazards to the staff during the operation